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Effectiveness of intensive rehabilitation on functional ability and quality of life after first total knee arthroplasty: a single-blind randomized controlled trial1

      Abstract

      Moffet H, Collet J-P, Shapiro SH, Paradis G, Marquis F, Roy L. Effectiveness of intensive rehabilitation on functional ability and quality of life after first total knee arthroplasty: a single-blind randomized controlled trial. Arch Phys Med Rehabil 2004;85:546–56.

      Objective

      To evaluate the effectiveness of a new intensive functional rehabilitation (IFR) program on functional ability and quality of life (QOL) in persons who underwent a first total knee arthroplasty (TKA).

      Design

      Randomized controlled trial.

      Setting

      Ambulatory care.

      Participants

      Seventy-seven people with knee osteoarthritis.

      Intervention

      Two months after TKA, subjects were randomly assigned to either a group with IFR (n=38), who received 12 supervised rehabilitation sessions combined with exercises at home between months 2 and 4 after TKA, or to a control group (n=39), who received standard care. All participants were evaluated by a blind evaluator at baseline (2mo after TKA), immediately after IFR (2mo later; POST1), and 2 and 8 months later (POST2 and POST3).

      Main outcome measures

      The primary outcome measure with respect to effectiveness was the 6-minute walk test (6MWT) at POST2. Secondary outcome measures were the 6MWT at the other evaluations and the Western Ontario and McMaster Universities Osteoarthritis Index and Medical Outcomes Study 36-Item Short-Form Health Survey.

      Results

      Subjects in the IFR group walked longer distances (range, 23–26m) in 6 minutes at the 3 POST evaluations than subjects in the control group. At POST1 and POST2, they also had less pain, stiffness, and difficulty in performing daily activities. Positive changes in QOL in favor of the IFR were found only at POST2.

      Conclusions

      The IFR was effective in improving the short-term and mid-term functional ability after uncomplicated primary TKA. The magnitude of the IFR effect on the primary outcome was modest but consistent. More intensive rehabilitation should be promoted in the subacute recovery period after TKA, to optimize functional outcomes in the first year after surgery.

      Keywords

      REDUCTION IN PAIN and improvement in physical function and quality of life (QOL) are the main expected outcomes after total knee arthroplasty
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      Residual strength deficits as large as 35% were found in the knee extensor muscles 1 and 2 years after TKA for severe OA.
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      Time-course of natural locomotor recovery in the first year following knee arthroplasty.
      important clinical deficits persisted more than 1 year after TKA.
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      Kinesiologic measurements of functional performance before and after double compartment Marmor knee arthroplasty.
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      • Moffet H
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      Time-course of natural locomotor recovery in the first year following knee arthroplasty.
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      Reductions in gait speed ranging from 15% to 30% have been reported 6 months and 1 year after TKA.
      • Murray M.P
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      • Laney W.H
      • Gardner G.M
      • Mollinger A
      Kinesiologic measurements of functional performance before and after double compartment Marmor knee arthroplasty.
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      • Walsh M
      • Woodhouse L.J
      • Thomas S.G
      • Finch E
      Physical impairments and functional limitations a comparison of individuals 1 year after total knee arthroplasty with control subjects.
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      • Moffet H
      • Ouellet D
      • Parent E
      • Brisson M
      Time-course of natural locomotor recovery in the first year following knee arthroplasty.
      These speed deficits were similar in magnitude to the ones reported preoperatively
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      • Brisson M
      Time-course of natural locomotor recovery in the first year following knee arthroplasty.
      and 5.5 to 9 years (19%–33%) after TKA.
      • Skinner H.B
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      • Dhabel T.A
      • Cook S.D
      • Milicic M
      • Haddad R.J
      Correlation of gait analysis and clinical evaluation of polycentric total knee arthroplasty.
      ,
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      Correlation between clinical examination and quantitative gait analysis in patients operated upon with the Gunston-Hult knee prosthesis.
      During stair ascent, a locomotor task with a high degree of difficulty, the speed deficit was even greater (women, 43%; men, 51%) 1 year after TKA.
      • Walsh M
      • Woodhouse L.J
      • Thomas S.G
      • Finch E
      Physical impairments and functional limitations a comparison of individuals 1 year after total knee arthroplasty with control subjects.
      As with gait, the speed deficit was accompanied by abnormalities in leg movements, moments of force, and muscle activations during stair ascent and descent progression more than 2 years after TKA.
      • Walsh M
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      • Thomas S.G
      • Finch E
      Physical impairments and functional limitations a comparison of individuals 1 year after total knee arthroplasty with control subjects.
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      Gait biomechanics and the evolution of total joint replacement.
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      The influence of total knee-replacement design on walking and stair-climbing.
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      In a study
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      Patient-perceived functional outcomes associated with elective hip and knee arthroplasties.
      18 months after TKA, only 47% of the subjects perceived that they were better able to climb stairs than they were before surgery. Finally, despite the significant improvement seen in patients’ health-related quality of life (HRQOL), especially in physical function, role-physical, and bodily pain, in the first year after TKA, HRQOL remained significantly lower than age-related population norms, especially for persons younger than 75 years.
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      • Peerbhoy D
      • Shenkin A
      • Parker C
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      ,
      • van Essen G.J
      • Chipchase L.S
      • O’Connor D
      • Krishnan J
      Primary total knee replacement short-term outcomes in Australian population.
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      • Williams J.I
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      • Arshinoff R
      • Young N
      • Naylor D
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      • Jones A.C
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      In light of these findings, it is relevant to question the intensity and the duration of rehabilitation follow-up after TKA, which is often restricted to a few supervised sessions during the short in-hospital stay (7–10d), followed either by an unsupervised exercise program performed at home or by only a few physiotherapy (PT) visits at home in the first 2 months after TKA.
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      Until now, the impact of a more intensive functional rehabilitation (IFR) program—offered in the subacute stage and including both knee-specific and global lower-limb exercises, to improve locomotor performance and function in daily life activities—has not been evaluated in a randomized controlled study. However, the results of studies performed in arthritic populations strongly support the effectiveness of an adapted and intensive rehabilitation program, to promote better functional ability without inducing adverse joint effects.
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      In addition to improvements in functional ability, it is believed that such an intervention may positively influence long-term outcomes, such as health services utilization and knee prosthesis longevity.
      We conducted a single-blind randomized trial to evaluate the effectiveness of an IFR program, given between the second and fourth months after surgery, on the functional ability and QOL of persons who underwent a first TKA. Physical function has been identified as among the most important dimensions to be measured when evaluating intervention effectiveness in persons with OA.
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      Because locomotor ability can mirror the evolution of physical function, the primary outcome measure was the distance walked in 6 minutes, 2 months after the end of the IFR program (POST2 evaluation).

      Methods

      Participants

      Subjects were recruited from the surgical waiting lists of 23 orthopedic surgeons working in the 5 main hospitals of the Quebec City metropolitan area. All subjects were required (1) to have a diagnosis of primary OA of the knee, (2) to be waiting for a first TKA, (3) to live in the Quebec City metropolitan area, and (4) to be ambulatory with or without a walking aid. They were excluded if they (1) were planning a second surgery of the lower limbs during the first year after TKA, (2) had associated conditions impeding their performance of locomotor tests, (3) had had surgery of the lower limbs affecting their gait pattern, (4) had neuromuscular or neurodegenerative diseases, (5) had a knee infection after TKA or other major complications (eg, loosening or embolia excluding thrombophlebitis), or (6) if they had problems after the instructions of the study protocol.
      The study protocol was approved by the research ethics committees of the different hospitals and research center involved. All subjects participated voluntarily in the study and gave written informed consent.

      Study design

      All participants were randomly assigned to 2 groups 2 months after TKA: the IFR group received a supervised rehabilitation program between months 2 and 4 after TKA, and the control (CTL) group followed the standard care. The functional ability and QOL of all participants were evaluated by a blind evaluator at baseline (2mo after TKA), immediately after the IFR (4mo after TKA: POST1), and 2 and 8 months later (6mo and 12mo after TKA: POST2 and POST3).

      Interventions

      All participants were taught a standardized home-exercise program by experienced physiotherapists after their knee surgery and before they left the hospital. This program comprised simple exercises to retrain lower-limb strength (quadriceps, hamstrings, hip abductors and extensors) and to increase knee mobility, as well as some advice about knee positioning, ice application, and gait retraining.

      IFR program

      The IFR program was developed in accordance with motor learning and training specificity principles,
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      as well as with the results of other studies.
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      • Charlson M.E
      Supervised fitness walking in patients with osteoarthritis of the knee.
      ,
      • Minor M.A
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      • Perhonen M
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      Therapeutic exercise for rheumatoid arthritis and osteoarthritis.
      It started 2 months after TKA, because in the subacute recovery period, knee pain, effusion, and movement limitations are considerably improved and no longer restrict the practice of more intense functional exercises with partial and complete knee loading. The IFR program combined 12 supervised rehabilitation sessions with individualized home exercises performed on the days without supervised treatments. The same 2 physiotherapists gave the treatments and regularly adapted the IFR program to individuals’ needs and tolerance, to ensure optimal intensity of the intervention all along the treatment period.
      All subjects attended the 12 supervised rehabilitation sessions (duration, 60–90min) over a period of 6 to 8 weeks at the Quebec Rehabilitation Institute. We refer to the supervised rehabilitation sessions as S1 through S12. During these sessions, subjects were supervised and knee joint responses (range of motion, pain, effusion) were monitored to adjust and optimize the intervention. Each session included 5 components: warm-up, specific strengthening exercises, functional task-oriented exercises, endurance exercises, and cool-down (table 1). The specific strengthening exercises, performed in a supine or seated position, consisted of maximal isometric pain-free contractions (knee extensors and flexors), at different angles of knee flexion, and dynamic (concentric-eccentric) contractions against gravity (hip abductors). The isometric exercises were performed at multiple angles, because strength gains are known to be specific to the trained positions.
      • Lindh M
      Increase of muscle strength from isometric quadriceps exercises at different knee angles.
      ,
      • Sale D.G
      Neural adaptation to resistance training.
      In the first session, these types of exercises were chosen over concentric exercises, because pain-free knee muscle contractions can easily be performed. Angles where deficits were known to be present were specifically targeted. The functional exercises had different degrees of difficulty and complexity according to (1) the amount of weight bearing (partial to total support on the operated leg), (2) support (with or without upper limb support), (3) side (bilateral or unilateral exercise), (4) resistance (with or without external load), and (5) complexity (isolated or combined motion). Endurance exercises were either walking, biking, or both, for a progressive duration of 5 to 20 minutes.
      Table 1Description of the Supervised Rehabilitation Sessions (S1-S12) and the Compliance of Subjects (IFR group) to Planned Treatment Modalities (%)
      ModalitiesDuration Intensity
      The mean duration intensity at which a modality was received during the planned treatments. Only the data from the subjects who performed the exercise or received the modality were used to calculate a mean per session and then a mean ± SD over the sessions. For example, a mean of 10.5±1.4 repetitions of ISOM knee extensors strengthening (flexion, 0°) was performed during the first 2 sessions (S1, S2) by more than 90% of the subjects in the IFR group.
      (mean ± SD)
      S1S2S3S4S5S6S7S8S9S10S11S12
      Warm-up and stretching exs (5–10min)
      1. Global flexion-extension of the lower limb10.4±0.3 rep
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      2. Alternated dorsal plantarflexion of the ankles8.8±1.0 rep
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      3. Stretching of the hamstrings7.7±0.4 rep374237343437423437372629
      4. Mobility exs of the neck, upper limbs, and backNA000000000000
      Specific strengthening exs (15min)
      1. ISOM knee extensors: flex 0°10.5±0.7 rep
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      2. ISOM knee extensors: flex 60°10.2±0.3 rep
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      3. ISOM hamstrings: flex 60°10.4±0.5 rep
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      71
      4. CONC-ECC hip abductors16.9±0.6 rep
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Functional task-oriented exs (15–20min)
      1. Get up and sit down16.5±0.8 rep
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      2. Knee extensor strengthening in standing with Theraband18.0±2.2 rep
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      47321813
      3. Controlled bilateral knee flexion-extension in standing16.1±0.8 rep
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      7474
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      4. Unilateral knee flexion to 90° in standing17.9±0.7 rep
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      5. Climbing on a platform or a flight of stairs24.1±4.0 steps
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      6. Walking backward, on a slope and/or laterally while crossing lower limbs23.9±2.0m to 31.4±3.0m
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      7. Walking in place, with large amplitude of hip and knee flexion and upper-limb movements19.8±4.8 steps
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Endurance exs
      One or both of the endurance exercises had to be performed for a duration increasing from 5 to 20 minutes.
      (5–20min)
      1. Walking10.7±4.2min range, 6–17min4263
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      2. Stationary cycling5.2±1.0min range, 4–7min0388111613131618
      Cool down (10min)
      1. Slow walking1.7±0.6min5133588112621262626
      2. Stretching exs
      Global flexion-extension of the lower limb, alternated dorsal plantarflexion of the ankles, and/or stretching of the hamstrings.
      6.8±1.0 rep/exs63
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      66
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      58666355585560
      3. Ice11.8±0.4min182118211811888585
      NOTE. Empty cells indicate that the modality was neither planned nor given at the corresponding session.
      Abbreviations: CONC-ECC, concentric-eccentric; exs, exercises; ISOM, isometric; NA, not applicable; rep, repetitions; SD, standard deviation.
      The mean duration intensity at which a modality was received during the planned treatments. Only the data from the subjects who performed the exercise or received the modality were used to calculate a mean per session and then a mean ± SD over the sessions. For example, a mean of 10.5±1.4 repetitions of ISOM knee extensors strengthening (flexion, 0°) was performed during the first 2 sessions (S1, S2) by more than 90% of the subjects in the IFR group.
      One or both of the endurance exercises had to be performed for a duration increasing from 5 to 20 minutes.
      At least 90% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
      Global flexion-extension of the lower limb, alternated dorsal plantarflexion of the ankles, and/or stretching of the hamstrings.
      In the first 2 weeks (S1-S4), more attention was given to the warm-up, specific strengthening, and cool-down exercises, because they were less demanding on the knee joint. Simple functional exercises and endurance exercises of short duration (5min) were also started. During the second phase of rehabilitation (S5-S12), more time was spent practicing functional task-oriented exercises with increasing degrees of intensity and difficulty. The duration of the endurance exercises was gradually increased from 5 to 20 minutes. To control the intensity of these exercises, the patients’ heart rates were monitored continuously with a Sport Tester PE 300 cardiotachymeter.
      Polar Electro Inc, 370 Crossways Park Dr, Woodbury, NY 11797.
      The first time the exercises were performed (S3), the participants tried to reach 60% of their predicted heart rate at maximal exercise. This was increased to a maximum of 80% of the predicted heart rate.
      • Minor M.A
      • Hewett J.E
      • Webel R.R
      • Anderson S.K
      • Kay D.R
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      ,
      • Semble E.L
      • Loeser R.F
      • Wise C.M
      Therapeutic exercise for rheumatoid arthritis and osteoarthritis.
      At the end of the program, instructions about the continuation of home exercises and return to sports were given. More details on the content of the IFR program are given in table 1.

      Standard care

      Subjects in the CTL group did not follow the IFR program but received the usual care. For some, this included a series of supervised rehabilitation visits at home. No attempt to interfere with the usual care was made. Information about the frequency, duration, and content of the supervised rehabilitation interventions received by the subjects in the CTL group at home was obtained by questionnaire and by telephone interviews with the subjects and their physical therapists.

      Outcome measures

      The primary outcome measure with respect to the effectiveness of the IFR program was the distance walked in 6 minutes 2 months after the completion of the program (POST2 evaluation). Secondary outcome measures were the distance walked in 6 minutes at POST1 and POST3 and, for all POST evaluation times, the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index total score and subscale scores (pain, stiffness, difficulty) and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) scales and summary indices (8 health dimension scales, arthritis-specific, and generic physical and mental summary measures) were used.
      Participants’ demographic and clinical characteristics were obtained at baseline. Cointerventions, health complications, and level of physical activity
      • Godin G
      • Shephard R.J
      A simple method to assess exercise behavior in the community.
      were documented at each follow-up.

      Functional ability outcomes

      Six-minute walk test

      The 6-minute walk test (6MWT) measures the maximal distance covered by a subject walking at free speed during 6 minutes. It is perceived as an adequate measure of physical function and locomotor ability by subjects with disability and was recommended for this purpose in research projects with older adults and populations with cardiac problems.
      • Langenfeld H
      • Schneider B
      • Grimm W
      • et al.
      The six-minute walk—an adequate exercise test for pacemaker patients?.
      ,
      • Harada N.D
      • Chiu V
      • Stewart A.L
      Mobility-related function in older adults assessment with a 6-minute walk test.
      It has also been used to measure the effectiveness of interventions in populations with knee OA.
      • Kovar P.A
      • Allegrante J.P
      • MacKenzie R
      • Peterson M.G
      • Gutin B
      • Charlson M.E
      Supervised fitness walking in patients with osteoarthritis of the knee.
      ,
      • Peterson M.G
      • Kovar-Toledano P.A
      • Otis J.C
      • et al.
      Effect of a walking program on gait characteristics in patients with osteoarthritis.
      ,
      • Price L
      • Hewett J.E
      • Kay D.R
      • Minor M.A
      Five-minute walking test of aerobic fitness for people with arthritis.
      It was chosen as the primary outcome measure because of its sound measurement properties and especially because of its excellent responsiveness, which is known to increase over time (after 3mo after surgery) in persons with TKA.
      • Kreibich D.N
      • Vaz M
      • Bourne R.B
      • et al.
      What is the best way of assessing outcome after total knee replacement?.
      ,
      • Parent E
      • Moffet H
      Comparative responsiveness of locomotor tests and questionnaires used to follow early recovery after total knee arthroplasty.
      In contrast, the responsiveness of the WOMAC has been found to be better than the 6MWT in the early stages of recovery (first 3mo).
      • Parent E
      • Moffet H
      Comparative responsiveness of locomotor tests and questionnaires used to follow early recovery after total knee arthroplasty.
      In our study, the 6MWT was performed once in a 50-m-long corridor. Subjects walked back and forth over this distance as many times as possible for a period of 6 minutes. A walking aid was used, and rest periods were allowed when needed. The construct and concurrent validity of this test have been extensively shown in populations with cardiopulmonary problems.
      • Langenfeld H
      • Schneider B
      • Grimm W
      • et al.
      The six-minute walk—an adequate exercise test for pacemaker patients?.
      ,
      • Guyatt G.H
      • Thompson P.J
      • Berman L.B
      • et al.
      How should we measure function in patients with chronic heart and lung disease?.
      ,
      • Bittner V
      • Weiner D.H
      • Yusuf S
      • et al.
      Prediction of mortality and morbidity with a 6-minute walk test in patients with left ventricular dysfunction. SOLVD Investigators.
      ,
      • Guyatt G.H
      • Sullivan M.J
      • Thompson P.J
      • et al.
      The 6-minute walk a new measure of exercise capacity in patients with chronic heart failure.
      In populations with OA, good concurrent validity was also shown with respiratory measures,
      • Price L
      • Hewett J.E
      • Kay D.R
      • Minor M.A
      Five-minute walking test of aerobic fitness for people with arthritis.
      ,
      • Rejeski W.J
      • Ettinger W.H.J
      • Schumaker S
      • James P
      • Burns R
      • Elam J.T
      Assessing performance-related disability in patients with knee osteoarthritis.
      knee extensor strength,
      • Rejeski W.J
      • Ettinger W.H.J
      • Schumaker S
      • James P
      • Burns R
      • Elam J.T
      Assessing performance-related disability in patients with knee osteoarthritis.
      and stride characteristics.
      • Peterson M.G
      • Kovar-Toledano P.A
      • Otis J.C
      • et al.
      Effect of a walking program on gait characteristics in patients with osteoarthritis.
      Additionally, it has a good test-retest reliability, even without any familiarization trials,
      • Harada N.D
      • Chiu V
      • Stewart A.L
      Mobility-related function in older adults assessment with a 6-minute walk test.
      ,
      • Guyatt G.H
      • Thompson P.J
      • Berman L.B
      • et al.
      How should we measure function in patients with chronic heart and lung disease?.
      ,
      • Rejeski W.J
      • Ettinger W.H.J
      • Schumaker S
      • James P
      • Burns R
      • Elam J.T
      Assessing performance-related disability in patients with knee osteoarthritis.
      and was found to be the most responsive locomotor test among those administered to persons after TKA.
      • Kreibich D.N
      • Vaz M
      • Bourne R.B
      • et al.
      What is the best way of assessing outcome after total knee replacement?.
      ,
      • Parent E
      • Moffet H
      Comparative responsiveness of locomotor tests and questionnaires used to follow early recovery after total knee arthroplasty.
      Improvements ranging from 30 to 60m (or 15%–18%) were considered clinically significant in persons with pulmonary diseases.
      • Guyatt G.H
      • Thompson P.J
      • Berman L.B
      • et al.
      How should we measure function in patients with chronic heart and lung disease?.
      ,
      • Guyatt G.H
      • Townsend M
      • Pugsley S.O
      • et al.
      Bronchodilators in chronic air-flow limitation. Effects on airway function, exercise capacity, and quality of life.
      ,
      • Redelmeier D.A
      • Bayoumi A.M
      • Goldstein R.S
      • Guyatt G.H
      Interpreting small differences in functional status the Six Minute Walk test in chronic lung disease patients.
      ,
      • Leach R.M
      • Davidson A.C
      • Chinn S
      • Twort C.H
      • Cameron I.R
      • Bateman N.T
      Portable liquid oxygen and exercise ability in severe respiratory disability.

      WOMAC osteoarthritis index

      The WOMAC is a disease-specific questionnaire developed specifically for people with OA of the hip and knee. Using visual analog scales, its 24 items probe 3 dimensions—pain (5 items), stiffness (2 items), and functional difficulty (17 items)—judged important by such individuals. The total score (n=23 items) and the dimension scores (range, 0–100, with 100 indicating the worst possible state) correspond to the sum of the related items divided by the total number of items considered. The WOMAC questionnaire is well recognized for its good validity, reliability, and responsiveness.
      • Kreibich D.N
      • Vaz M
      • Bourne R.B
      • et al.
      What is the best way of assessing outcome after total knee replacement?.
      ,
      • Parent E
      • Moffet H
      Comparative responsiveness of locomotor tests and questionnaires used to follow early recovery after total knee arthroplasty.
      ,
      • Bellamy N
      • Buchanan W.W
      • Goldsmith C.H
      • Campbell J
      • Stitt L
      Validation study of WOMAC a health status instrument for measuring clinically-important patient-relevant outcomes following total hip or knee arthroplasty in osteoarthritis.
      ,
      • Wright J.G
      • Young N.L
      A comparison of different indices of responsiveness.
      ,
      • Davies G.M
      • Watson D.J
      • Bellamy N
      Comparison of the responsiveness and relative effect size of the Western Ontario and McMaster Universities Osteoarthritis Index and the short-form Medical Outcomes Study Survey in a randomized, clinical trial of osteoarthritis patients.
      ,
      • Brazier J.E
      • Harper R
      • Munro J
      • Walters S.J
      • Snaith M.L
      Generic and condition-specific outcome measures for people with osteoarthritis of the knee.
      The French-Canadian version of WOMAC was used.
      • Choquette D
      • Bellamy N
      • Raynauld J.P
      A French-Canadian version of the WOMAC osteoarthritis index.

      QOL outcome

      The SF-36 questionnaire is an HRQOL outcome measure with good metrologic properties.
      • Wright J.G
      • Young N.L
      A comparison of different indices of responsiveness.
      ,
      • Davies G.M
      • Watson D.J
      • Bellamy N
      Comparison of the responsiveness and relative effect size of the Western Ontario and McMaster Universities Osteoarthritis Index and the short-form Medical Outcomes Study Survey in a randomized, clinical trial of osteoarthritis patients.
      ,
      • Brazier J.E
      • Harper R
      • Munro J
      • Walters S.J
      • Snaith M.L
      Generic and condition-specific outcome measures for people with osteoarthritis of the knee.
      ,
      • Kosinski M
      • Keller S.D
      • Hatoum H.T
      • Kong S.X
      • Ware Jr, J.E
      The SF-36 Health Survey as a generic outcome measure in clinical trials of patients with osteoarthritis and rheumatoid arthritis tests of data quality, scaling assumptions and score reliability.
      ,
      • Kosinski M
      • Keller S.D
      • Ware Jr, J.E
      • Hatoum H.T
      • Kong S.X
      The SF-36 Health Survey as a generic outcome measure in clinical trials of patients with osteoarthritis and rheumatoid arthritis relative validity of scales in relation to clinical measures of arthritis severity.
      ,
      • McHorney C.A
      • Ware J.E
      • Raczek A.E
      The MOS 36-Item Short-Form Health Survey (SF-36) II. Psychometric and clinical tests of validity in measuring physical and mental health constructs.
      ,
      • Ware Jr, J.E
      • Sherbourne C.D
      The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection.
      It is increasingly used in populations with OA.
      • March L.M
      • Cross M.J
      • Lapsley H
      • et al.
      Outcomes after hip or knee replacement surgery for osteoarthritis. A prospective cohort study comparing patients’ quality of life before and after surgery with age-related population norms.
      ,
      • Wright J.G
      • Young N.L
      A comparison of different indices of responsiveness.
      ,
      • Kosinski M
      • Keller S.D
      • Hatoum H.T
      • Kong S.X
      • Ware Jr, J.E
      The SF-36 Health Survey as a generic outcome measure in clinical trials of patients with osteoarthritis and rheumatoid arthritis tests of data quality, scaling assumptions and score reliability.
      ,
      • Kosinski M
      • Keller S.D
      • Ware Jr, J.E
      • Hatoum H.T
      • Kong S.X
      The SF-36 Health Survey as a generic outcome measure in clinical trials of patients with osteoarthritis and rheumatoid arthritis relative validity of scales in relation to clinical measures of arthritis severity.
      ,
      • Keller S.D
      • Majkut T.C
      • Kosinski M
      • Ware Jr, J.E
      Monitoring health outcomes among patients with arthritis using the SF-36 Health Survey overview.
      ,
      • Keller S.D
      • Ware Jr, J.E
      • Hatoum H.T
      • Kong S.X
      The SF-36 Arthritis-Specific Health Index (ASHI): II. Tests of validity in four clinical trials.
      It contains 36 items that assess 8 different health dimensions: physical functioning, social functioning, role-physical, bodily pain, mental health, role-emotional, vitality, and general health. Health dimension scales were computed as described by the researchers
      • Ware Jr, J.E
      • Snow K
      • Kosinski M
      • Gandek B
      and were combined to obtain the summary indices: the Physical Component Summary (PCS), Mental Component Summary (MCS), and Arthritis-Specific Health Index (ASHI).
      • Keller S.D
      • Ware Jr, J.E
      • Hatoum H.T
      • Kong S.X
      The SF-36 Arthritis-Specific Health Index (ASHI): II. Tests of validity in four clinical trials.
      ,
      • Ware Jr, J.E
      • Kosinski M
      • Keller D
      This last index was recently validated. It is calculated using a set of weights, which maximizes the specificity of the test for populations with arthritis.
      • Keller S.D
      • Ware Jr, J.E
      • Hatoum H.T
      • Kong S.X
      The SF-36 Arthritis-Specific Health Index (ASHI): II. Tests of validity in four clinical trials.
      ,
      • Ware Jr, J.E
      • Kosinski M
      • Keller D
      Scores resulting from these summary indices vary from 0 to 100, with higher scores indicating the most favorable state of health. The French-Canadian translation of the SF-36 was used in our study.
      • Wood-Dauphinee S
      • Gauthier L
      • Gandek B
      • Magnam L
      • Pierre U
      Readying a US measure of health status, the SF-36, for use in Canada.

      Sample size

      The sample size needed to detect a significant difference (2-sided, P=.05) of at least 15% between groups in the distance walked in 6 minutes (primary outcome; change from baseline) with an assumed standard deviation (SD) of 20% and a 0.8 power was 29 subjects per group. To compensate for a 15% to 20% loss of subjects between baseline and follow-up, 36 subjects per group (72 in total) were required.
      The magnitude of the clinically important difference between groups was estimated from the study by Kovar et al
      • Kovar P.A
      • Allegrante J.P
      • MacKenzie R
      • Peterson M.G
      • Gutin B
      • Charlson M.E
      Supervised fitness walking in patients with osteoarthritis of the knee.
      in which an improvement of 18% (95% confidence interval [CI], 10%–27%) in 6-minute walk distance was found in subjects with knee OA after a 12-week supervised fitness walking program. In the same study, an SD of less than 10% was obtained. Considering that our population was different (post-TKA subjects for severe OA), we decided to adopt a more conservative attitude, by assuming a larger variability (SD=20%) of the responses to the interventions (standard care, IFR). Thus, with an SD of 10% and the same number of subjects (29/group), it would be possible to detect as statistically significant a difference of 8%, if such a difference exists with a power of 80%.

      Randomization

      A stratification by hospital with blocking within strata (block size: 4 or 2 randomly distributed) was used to ensure a good balance between both groups in terms of characteristics and size. A computer-generated randomization list
      SAS proc plan; SAS Institute, 100 SAS Campus Dr, Cary, NC 27513.
      was prepared by the statistician and given to the study’s clinical coordinator in a series of sealed envelopes. After patient eligibility was confirmed and the baseline evaluation was performed, the study coordinator proceeded to randomization by opening the appropriate numbered envelope. Subjects were informed of the result by phone the day after their baseline evaluation (POST1). Precise directives were given to the subjects by the study’s clinical coordinator, according to their assigned group. The randomization code was given to the investigators when the study was completed.

      Blinding

      Blinding of subjects and treatment providers was not possible in our study. However, to minimize bias, an objective criterion was chosen as the primary outcome measure, standardized outcome assessment procedures were defined, and training was given to the evaluators. All evaluators and investigators were blinded to group assignment for the duration of the study. The statistician performed the analyses and presented unblinded data to the investigators after the completion of the study. All decisions related to data analyses were taken while the investigators were still unaware of group assignment.

      Statistical methods

      Descriptive statistics of both group statuses at baseline were calculated. Considering the selective loss to follow-up that occurred in the CTL group (fig 1), a per-protocol analysis was performed. This analysis was restricted to subjects who fulfilled the protocol in terms of eligibility and outcome assessment. Results of this per-protocol analysis are reported in this article. An intention-to-treat analysis, based on all participants as originally assigned, was also performed. Because of the imputation of data from the last available assessment to all subsequent evaluations in only the CTL group subjects, the analysis favored the IFR group (especially at POST3). Therefore, we chose to present the per-protocol analysis, which showed the most conservative treatment effect.
      Figure thumbnail GR1
      Fig 1Participant flow through each stage of the trial.
      Change scores were calculated by subtracting the baseline scores from the follow-up scores. The change scores were compared between groups (IFR, CTL) at each time period, using an analysis of covariance (ANCOVA) with the baseline level of each outcome measure used as a covariate to improve the precision of the effect estimates. Group differences in the magnitude of adjusted change from baseline (treatment effects) and their 95% CIs were computed for all outcome measures.

      Results

      Seventy-seven subjects were recruited between January 1997 and April 1999. Thirty-eight subjects were randomly assigned to the IFR group and 39 subjects to the CTL group. Both groups were comparable at baseline, according to their clinical and demographic characteristics (table 2). They also had comparable levels of functional ability and QOL at baseline (table 2).
      Table 2Baseline Characteristics of Both Groups of Subjects
      CharacteristicGroup CTL (n=39)Group IFR (n=38)
      Age (y)68.7±8.366.7±8.7
      Disease duration (y)13.0±8.712.5±8.9
      Gender: women22 (56)24 (63)
      Right knee replacement22 (56)19 (50)
      Previous orthopedic surgery15 (39)13 (34)
      Taking drug to relieve knee pain34 (87)36 (95)
      Impairment in other lower-limb joints27 (69)24 (63)
      Comorbidity
      Cardiac disease7 (18)10 (26)
      Chronic pulmonary disease4 (10)1 (3)
      Hypertension13 (33)13 (34)
      Diabetes4 (10)3 (8)
      Kidney disease1 (3)0 (0)
      Neurologic disease1 (3)1 (3)
      Cancer3 (8)1 (3)
      Practicing physical activity
      Physical Activity Index.41
      of
      High intensity0 (0)1 (3)
      Moderate intensity5 (13)5 (14)
      Low intensity13 (33)16 (43)
      6-minute walk distance (m)288.6±81.0299.2±89.4
      WOMAC (%)
      Total score26.2±18.829.7±19.0
      Pain score22.6±17.828.4±21.3
      Stiffness score36.3±25.339.1±27.5
      Difficulty score26.0±19.728.9±19.4
      SF-36 summary measures
      PCS35.3±8.432.8±7.6
      MCS55.6±10.652.5±11.6
      ASHI34.7±9.631.2±9.1
      NOTE. Values are mean ± SD or n (%).
      Physical Activity Index.
      • Godin G
      • Shephard R.J
      A simple method to assess exercise behavior in the community.
      Compliance with the IFR program was very high. The mean duration of the IFR program was 6±1 weeks (range, 3.9–8.9wk). All subjects in the IFR group participated in the 12 planned supervised sessions, with very good compliance with most of the planned modalities (table 1). Only 2 subjects benefited from additional supervised sessions after the end of the IFR program (fig 1). These additional rehabilitation sessions were given by other physical therapists unaware of the content of the IFR program. A quarter (26%) of the subjects in the CTL group received home PT services, with a mean of 7±3 visits (range, 2–12 visits) between months 2 and 4 after TKA. Ninety percent of the participants completed all stages of the study. The flow of participants through each stage of the study is illustrated in detail in figure 1.

      Outcomes

      Subjects in the IFR group walked a significantly longer distance (25m, 9%) in 6 minutes at POST2 (primary outcome), POST1 (23m, 8%), and POST3 (26m, 9%; P=.06) than did subjects in the CTL group (table 3, fig 2). At POST1 and POST2, they also had less pain (11%, 10%), stiffness (9%, 16%), and difficulty in performing daily activities (7%, 8%). At POST3, no difference between groups was found in the WOMAC total and subscales (table 3, fig 3).
      Table 3Functional Ability Outcomes
      Outcome MeasureMean ValueChange From BaselineTreatment Effect (95% CI)P Value (ANCOVA)
      Group CTLGroup IFRGroup CTLGroup IFR
      6-minute walk distance
      POST1346.7±95.3377.7±74.557.6±39.578.5±56.322.5 (1.1–44.0).040
      POST2360.3±77.4392.1±92.269.1±45.793.0±56.625.4 (2.7–48.1).029
      POST3369.7±80.1399.7±94.275.2±50.7100.6±66.526.4 (−1.3 to 54.0).061
      WOMAC
      Total score
      POST119.4±17.613.5±14.1−6.9±9.3−16.2±17.07.9 (2.7–13.1).004
      POST218.6±18.512.0±12.8−7.3±13.6−17.7±18.58.4 (2.4–14.5).007
      POST315.3±16.311.6±13.8−12.6±14.7−18.0±20.54.3 (−2.1 to 10.7).190
      Pain score
      POST117.2±17.19.6±11.5−4.9±10.9−18.8±18.610.6 (5.4–15.9).000
      POST216.0±18.18.9±9.6−5.6±13.6−19.5±20.19.7 (3.9–15.5).001
      POST311.8±13.09.4±12.4−11.2±12.7−19.0±21.73.9 (−1.6 to 9.5).161
      Stiffness score
      POST128.8±25.722.1±25.3−7.1±16.8−17.0±28.78.5 (−0.9 to 18.0).077
      POST225.2±24.916.2±19.6−10.2±21.2−23.0±31.016.3 (0.9–19.7).032
      POST319.3±20.913.7±16.8−17.2±22.8−25.4±30.36.2 (−2.4 to 14.8).157
      Difficulty score
      POST118.9±17.713.6±15.0−7.5±11.0−15.3±17.46.8 (1.2–12.3).017
      POST218.6±18.712.4±14.4−7.5±14.7−16.6±18.47.7 (1.4–13.9).017
      POST315.8±17.612.0±14.8−12.5±16.6−16.9±20.74.0 (−2.9 to 11.0).254
      NOTE. The treatment effect is the between-group difference in the adjusted mean change values. Positive values indicate positive treatment effect in favor of the IFR group. Conversely, negative values indicate larger improvements in the CTL group than in the IFR group.
      Figure thumbnail GR2
      Fig 2Distance walked in 6 minutes by subjects in both groups, at baseline and at follow-up evaluations. Shaded area represents the mean performance (±1 SD) of a group of 21 healthy, age-matched individuals (mean age, 67±8y).
      Figure thumbnail GR3
      Fig 3WOMAC questionnaire total and subscale (pain, stiffness, difficulty) scores for both groups of subjects, at baseline and at follow-up evaluations. A decrease in scores represents an improvement in knee pain, stiffness, and/or functional ability.
      No difference was found between groups in the 8 SF-36 scales, except for role-physical at POST2, where the subjects in the IFR group tended to have a better score (mean difference, 18.8; 95% CI, –0.1 to 37.8; ANCOVA, P=.052). According to the QOL summary indices, a significant difference in favor of the IFR was found in the PCS at POST2 (table 4). The magnitude of the difference was, however, small (4.9%). The same conclusion applies for the MCS at POST2 (table 4).
      Table 4QOL Scales and Summary Results
      SF-36 Scales and Summary MeasuresMean ValueChange From BaselineTreatment Effect (95% CI)P Value (ANCOVA)
      Group CTLGroup IFRGroup CTLGroup IFR
      Physical function
      POST156.8±23.758.9±23.89.3±18.214.9±19.74.6 (−3.7 to 12.8).277
      POST258.3±18.962.4±23.810.0±21.718.3±20.36.3 (−2.2 to 14.8).146
      POST360.3±20.463.8±24.313.1±20.119.7±22.25.3 (−4.0 to 14.6).262
      Role-physical
      POST150.7±42.144.7±39.922.4±41.825.7±43.7−1.9 (−19.5 to 15.8).834
      POST252.7±44.469.1±38.323.6±54.050.0±42.718.8 (−0.1 to 37.8).052
      POST372.6±36.170.4±37.641.9±45.851.3±40.71.3 (−16.2 to 18.8).881
      Bodily pain
      POST157.5±19.458.8±22.95.6±23.914.3±21.84.4 (−4.5 to 13.3).328
      POST263.2±22.263.6±22.710.7±22.519.2±25.04.0 (−5.6 to 13.6).413
      POST363.6±19.063.7±21.48.7±23.919.2±24.73.4 (−6.3 to 13.0).489
      Social function
      POST179.3±17.078.9±22.910.2±20.916.4±25.02.4 (−5.5 to 6.4).549
      POST278.7±16.682.6±20.99.5±26.720.1±25.85.6 (−2.5 to 13.8).172
      POST384.3±16.184.9±22.013.3±24.422.4±26.53.2 (−5.5 to 12.0).463
      Mental health
      POST180.9±14.478.4±16.43.8±16.57.4±14.20.6 (−5.2 to 6.4).837
      POST283.4±12.176.3±15.56.3±16.75.3±15.6−4.6 (−10.1 to 0.9).100
      POST382.7±14.076.4±17.75.8±17.65.4±20.0−4.2 (−11.5 to 3.1).253
      Role-emotional
      POST193.9±20.381.6±34.415.8±36.19.6±37.9−10.4 (−22.2 to 1.4).083
      POST294.6±20.186.0±30.617.1±44.214.0±40.7−7.9 (−19.7 to 3.9).188
      POST393.5±21.885.1±33.514.0±29.513.2±42.1−6.0 (−8.9 to 6.8).350
      Vitality
      POST171.1±14.767.4±20.07.5±14.09.1±13.9−0.1 (−6.0 to 5.9).974
      POST271.6±12.667.9±18.07.4±16.99.6±13.8−0.7 (−6.7 to 5.3).812
      POST373.2±14.270.1±20.19.5±15.111.8±17.80.0 (−7.4 to 7.3).993
      General health
      POST174.8±14.971.9±23.2−2.8±9.70.7±17.72.1 (−4.4 to 8.6).518
      POST275.9±13.373.0±21.0−2.1±13.11.8±15.21.7 (−4.5 to 7.8).593
      POST373.6±15.575.4±20.4−3.2±12.84.2±14.46.0 (−0.5 to 12.4).068
      PCS
      POST138.3±9.738.8±9.93.1±7.86.0±9.02.2 (−1.6 to 5.9).249
      POST239.3±9.142.8±9.33.8±9.210.0±8.64.9 (1.1 to 8.8).012
      POST341.7±7.443.6±9.46.1±8.310.8±10.12.9 (−1.0 to 6.9).144
      MCS
      POST158.5±7.555.7±9.03.2±9.03.2±8.9−1.5 (−4.6 to 1.6).333
      POST258.8±5.154.8±7.33.6±11.42.3±9.5−3.4 (−6.1 to –0.7).015
      POST358.4±7.155.0±10.02.9±8.32.5±11.9−2.3 (−6.2 to 1.6).245
      ASHI
      POST138.5±9.738.9±11.04.0±9.67.7±10.02.7 (−1.7 to 7.0).271
      POST240.6±10.042.2±10.65.8±9.911.0±9.93.0 (−1.1 to 7.1).095
      POST342.1±8.842.5±10.06.7±10.911.3±10.72.0 (−1.9 to 6.9).396
      NOTE. The treatment effect is the between-group difference in the adjusted mean change value. A positive value indicates a larger improvement in QOL in the IFR group than in the CTL group.

      Adverse events and loss to follow-up

      No adverse event was reported in any group. A selective loss to follow-up occurred in the CTL group (8 subjects; fig 1). Most of these losses took place at the last follow-up (POST3; n=6) and were attributable to either the need for a contralateral knee surgery (n=2), a lack of motivation (n=1), or an unrelated health condition (cancer, n=1). Two subjects, however, had a problem with their operated knee, namely, an infection or an instability requiring a second surgery.

      Cointerventions

      The proportion of subjects taking medication did not differ significantly between groups at each follow-up. Only a few subjects received PT treatments more than 4 months after TKA, and they were evenly distributed in both groups: 2 subjects per group had PT treatments between POST1 and POST2, whereas only 1 patient per group had such treatments between POST2 and POST3. None of the participants consulted a professional in occupational therapy, chiropractic, or acupuncture at any point in time. In the period between 2 consecutive follow-ups, the same proportion of subjects per group visited their orthopedic surgeon and general practitioner. Subjects in both groups reported similar levels of physical activity in the interval between 2 consecutive follow-ups, except for the time interval between baseline evaluation and POST2. During this period, a higher proportion of subjects (P=.03) in the CTL group (47%) were enrolled in low-intensity physical activities than were subjects in the IFR group (24%). However, participation in physical activities included in the IFR (home exercises and supervised sessions, including biking and walking activities) was not captured by the questionnaire, which may explain this result.

      Discussion

      The results of our study confirm the effectiveness of an IFR program in promoting better functional ability at short-term and midterm after a first TKA for severe OA. Subjects in the IFR group walked significantly longer distances in 6 minutes than did subjects in the CTL group immediately and 2 months after the IFR program, and they tended to maintain their additional gains after 8 months. Moreover, they had less pain, stiffness, and difficulty in performing daily activities at the first 2 follow-up evaluations. At POST3, however, both groups had a low level (≃15%) of knee pain, stiffness, and difficulty in performing daily activities, and no further differences were found between groups. Finally, no significant differences were found between groups in QOL except at POST2 for the role-physical dimension and the PCS (intergroup difference=19% in role-physical; 5% in PCS in favor of the IFR group).
      The magnitude of the IFR effect on the primary outcome was modest but consistent in terms of the gains in distance walked in meters. The additional distance covered in 6 minutes by the subjects in the IFR group varied from 23 to 26m at the 3 follow-up evaluations. This was sufficient to reach the lower limit of normal age-related performances at POST2 (fig 2). Compared with the baseline performance (mean, 299m), however, this represents, at best, a treatment effect of 9%. This is below the mean treatment effect (18%) reported by Kovar et al26 for subjects with knee OA, but close to the lower limit of the reported CI for treatment effect (95% CI, 10%–27%). The longer duration of their supervised fitness walking program (12wk vs 6wk in our study) and their use of a nonsurgical population may explain the discrepancy in results. In our study, a longer duration and/or a higher intensity of IFR may have induced a larger effect on the outcomes. The effect of the IFR also approaches the lower limit of the clinically significant change (30–60m) proposed for populations with pulmonary diseases.
      • Guyatt G.H
      • Thompson P.J
      • Berman L.B
      • et al.
      How should we measure function in patients with chronic heart and lung disease?.
      ,
      • Guyatt G.H
      • Townsend M
      • Pugsley S.O
      • et al.
      Bronchodilators in chronic air-flow limitation. Effects on airway function, exercise capacity, and quality of life.
      ,
      • Redelmeier D.A
      • Bayoumi A.M
      • Goldstein R.S
      • Guyatt G.H
      Interpreting small differences in functional status the Six Minute Walk test in chronic lung disease patients.
      ,
      • Leach R.M
      • Davidson A.C
      • Chinn S
      • Twort C.H
      • Cameron I.R
      • Bateman N.T
      Portable liquid oxygen and exercise ability in severe respiratory disability.
      Unfortunately, no such information is available for our population. The fact that the effectiveness of the IFR has been established in comparison with the standard care, which included for a significant proportion (26%) of the subjects a series of supervised PT visits at home (mean, 7±3 visits; range, 2–12 visits) between months 2 and 4 after TKA, may have minimized the difference between groups. Thus, the differences in outcomes between groups are probably less than would have occurred if the CTL group had received no rehabilitation intervention. Finally, in interpreting the magnitude of the IFR effect, it is also worthwhile to highlight the large variability in the response to the intervention (lower and upper limits of the treatment effect CI varied from –1.3 to 54m). Some subjects were definitely better responders to the IFR than others. Identification of subjects’ characteristics and factors that are related to a better response to this type of intervention may help clinicians organize rehabilitation services more efficiently in the future.
      The faster locomotor recovery, combined with the ability to perform daily activities with less pain, stiffness, and difficulty, most likely contributed to favoring a more active lifestyle, at least in the short-term and midterm, in subjects from the IFR group. This could have been a determining factor in avoiding physical immobility, which is a risk factor for developing health complications, isolation, and depression in the elderly.
      • Hébert R
      Syndrome d’immobilisation.
      The higher scores in the PCS (5%), ASHI (3%, trend P=.09), and especially in the role-physical domain (19%) of the SF-36 two months after the IFR (POST2) also support the positive impact of the intervention, because a 5-point difference between groups or over time is considered clinically relevant.
      • Ware Jr, J.E
      • Snow K
      • Kosinski M
      • Gandek B
      According to Shields et al,
      • Shields R.K
      • Enloe L.J
      • Leo K.C
      Health related quality of life in patients with total hip and knee replacement.
      these higher scores mean that the subjects who received the IFR program had fewer problems with work or other daily activities because of physical health (role-physical meaning), had less physical limitation, had fewer disabilities and fewer decrements in well-being, and had higher energy levels and better health (PCS meaning) than did subjects in the CTL group.
      The IFR program did not induce adverse joint effects, and overall compliance with the program was excellent. This suggests that a good balance was achieved between the dosage (duration, intensity, frequency) of the planned intervention and the objectives of developing a safe, readily accepted, and feasible rehabilitation program. Although only simple modalities were used in this program, its application required human resources to provide the participants with a high degree of supervision. In our experience, most participants need feedback and guidance to properly perform the exercises. Also, the dosage of the intervention has to be adapted to the individual’s needs and tolerance. This program could have been implemented on a group basis; however, because the participants were recruited prospectively, individual supervision was offered in our study. In the future, other ways of implementing such a program (exercise class, community program, individual home-based program with periodic supervision) should be explored, as well as a higher dosage, to ensure that a larger number of people benefit from it and to obtain a larger treatment effect.
      In addition to better knee function, compensation from adjacent lower-limb joints and the sound lower limb, better cardiorespiratory function, and other nonspecific effects of expectation may explain the better functional ability of the subjects in the IFR group. To better understand the impact of the IFR on functional ability (ie, 6-min walking distance) and, more specifically, on the operated knee function, biomechanical and spatiotemporal parameters of gait and stair ascent and knee extensor strength and mobility measures were also recorded. Detailed results concerning these explanatory outcomes will be provided in another article.
      Finally, even though the IFR program promoted better functional recovery in the first 12 months after TKA, the level of functional ability of healthy age-matched individuals was not necessarily reached. For the distance walked in 6 minutes, a total of 30 of 69 subjects (43.5%) had a locomotor performance within the normal range values (mean, 448m; 95% CI, 423–473m) 1 year after TKA. Of these subjects, 20 were in the IFR group (mean, 483±46m) and 10 were in the CTL group (mean, 493±65m). Thus, at the last follow-up, 53% of the subjects in the IFR group had a normal performance as compared with 32% in the CTL group. With respect to QOL, both groups scored within the normative ranges of an age-matched Canadian population, except on 4 domains of the SF-36: physical function, bodily pain, role-physical, and social function. The largest reduction was observed in the physical function and bodily pain domains, which remained more than 10% below normal values.
      • Hopman W.M
      • Towheed T
      • Anastassiades T
      • et al.
      Canadian normative data for the SF-36 health survey. Canadian Multicentre Osteoporosis Study Research Group.
      Our results apply to people who have undergone a first uncomplicated TKA for severe OA. It is not clear whether the same results could be obtained in subjects with other preoperative diagnoses (rheumatoid arthritis, trauma, avascular necrosis), after bilateral knee arthroplasty, after revisions, or in people with previous surgery in other lower-limb joints. The inclusion of subjects who had been operated on by several surgeons from 5 hospitals and the high participation rate in the intervention and follow-up evaluations contribute to the generalizability of the results.

      Conclusions

      The IFR was effective in improving the short-term and mid-term functional ability after uncomplicated primary TKA. More intensive rehabilitation should be promoted in the subacute recovery period after TKA, to optimize functional outcomes in the first year after surgery. Future work will highlight the long-term impact (3y after surgery) of the IFR program on functional ability and QOL, as well as its effects on the use of health services.
      Suppliers

      Acknowledgements

      We thank the orthopedic surgeons and the physical therapists for their invaluable contributions to the study. We are also grateful to Mélanie Brisson, Éric Parent, Marc Perron, and Caroline St-Pierre for their precious assistance, Nicole Martel for her involvement in providing the IFR program, Thierry Ducruet for the statistical analyses, and Isabelle Deaudelin for her help with graphical illustrations.

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