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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
Department of Rehabilitation, Laval University, Quebec City, CanadaCenter for Interdisciplinary Research in Rehabilitation and Social Integration, Montreal, Canada
Orthopedic Department, CHA, Hôpital de l’Enfant-Jésus, Quebec City (Paradis); and Orthopedic Department, CHUQ, Hôtel-Dieu de Québec, Quebec City, QC, Canada
Orthopedic Department, CHA, Hôpital de l’Enfant-Jésus, Quebec City (Paradis); and Orthopedic Department, CHUQ, Hôtel-Dieu de Québec, Quebec City, QC, Canada
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.
Tricompartmental knee replacement. A comparison of orthopaedic surgeons’ self reported performance rates with surgical indications, contraindications, and expected outcomes. Knee Replacement Patient Outcomes Research Team.
(TKA). Scientific and clinical evidence supports the success of TKA for the relief of knee pain and symptoms of osteoarthritis (OA), as well as a high rate of patient satisfaction.
However, the functional benefits of this surgical procedure are not as convincing, because quantitative evaluations of knee function have shown that large functional deficits persist 1 year after surgery and even longer.
Time-course of natural locomotor recovery in the first year following knee arthroplasty.
in: Arsenault A.B McKinley P McFadyen B Proceedings of the Twelfth ISEK Congress; 1998 June 27–30; Montreal (QC). Univ of Montreal,
Montreal (QC)1998: 230-231
Although a large improvement occurred in most of the kinematic and kinetic variables of gait from the second month to the end of the first year after TKA,
Time-course of natural locomotor recovery in the first year following knee arthroplasty.
in: Arsenault A.B McKinley P McFadyen B Proceedings of the Twelfth ISEK Congress; 1998 June 27–30; Montreal (QC). Univ of Montreal,
Montreal (QC)1998: 230-231
Time-course of natural locomotor recovery in the first year following knee arthroplasty.
in: Arsenault A.B McKinley P McFadyen B Proceedings of the Twelfth ISEK Congress; 1998 June 27–30; Montreal (QC). Univ of Montreal,
Montreal (QC)1998: 230-231
Time-course of natural locomotor recovery in the first year following knee arthroplasty.
in: Arsenault A.B McKinley P McFadyen B Proceedings of the Twelfth ISEK Congress; 1998 June 27–30; Montreal (QC). Univ of Montreal,
Montreal (QC)1998: 230-231
Time-course of natural locomotor recovery in the first year following knee arthroplasty.
in: Arsenault A.B McKinley P McFadyen B Proceedings of the Twelfth ISEK Congress; 1998 June 27–30; Montreal (QC). Univ of Montreal,
Montreal (QC)1998: 230-231
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.
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.
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.
Med J Aust.1999; 171 (Comment in: Med J Aust 1999;171:229–30): 235-238
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.
Capacité fonctionnelle et qualité de vie des patients atteints d’ostéo-arthrite avant et deux mois après une arthroplastie du genou [MSc thesis]. Laval Univ,
Quebec City (QC)1998
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.
A randomized trial comparing aerobic exercise and resistance exercise with a health education program in older adults with knee osteoarthritis. The Fitness Arthritis and Seniors Trial (FAST).
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.
Recommendations for a core set of outcome measures for future phase III clinical trials in knee, hip, and hand osteoarthritis. Consensus development at OMERACT III.
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,
Muscle weakness due to reflex inhibition future research in different areas of rehabilitation.
in: Proceedings of the 10th International Congress of the World Confederation for Physical Therapy. Australian Physiotherapy Association,
Sydney1987: 416-420
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.
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 (%)
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.
Between 75% and 89% of the participants in the IFR group received the modality with the expected duration and/or intensity.
58
66
63
55
58
55
60
3. Ice
11.8±0.4min
18
21
18
21
18
11
8
8
8
5
8
5
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.
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
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.
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.
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.
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.
Validation study of WOMAC a health status instrument for measuring clinically-important patient-relevant outcomes following total hip or knee arthroplasty in osteoarthritis.
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.
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.
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.
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.
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.
Med J Aust.1999; 171 (Comment in: Med J Aust 1999;171:229–30): 235-238
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.
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.
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
and were combined to obtain the summary indices: the Physical Component Summary (PCS), Mental Component Summary (MCS), and Arthritis-Specific Health Index (ASHI).
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.
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.
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
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.
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
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 Measure
Mean Value
Change From Baseline
Treatment Effect (95% CI)
P Value (ANCOVA)
Group CTL
Group IFR
Group CTL
Group IFR
6-minute walk distance
POST1
346.7±95.3
377.7±74.5
57.6±39.5
78.5±56.3
22.5 (1.1–44.0)
.040
POST2
360.3±77.4
392.1±92.2
69.1±45.7
93.0±56.6
25.4 (2.7–48.1)
.029
POST3
369.7±80.1
399.7±94.2
75.2±50.7
100.6±66.5
26.4 (−1.3 to 54.0)
.061
WOMAC
Total score
POST1
19.4±17.6
13.5±14.1
−6.9±9.3
−16.2±17.0
7.9 (2.7–13.1)
.004
POST2
18.6±18.5
12.0±12.8
−7.3±13.6
−17.7±18.5
8.4 (2.4–14.5)
.007
POST3
15.3±16.3
11.6±13.8
−12.6±14.7
−18.0±20.5
4.3 (−2.1 to 10.7)
.190
Pain score
POST1
17.2±17.1
9.6±11.5
−4.9±10.9
−18.8±18.6
10.6 (5.4–15.9)
.000
POST2
16.0±18.1
8.9±9.6
−5.6±13.6
−19.5±20.1
9.7 (3.9–15.5)
.001
POST3
11.8±13.0
9.4±12.4
−11.2±12.7
−19.0±21.7
3.9 (−1.6 to 9.5)
.161
Stiffness score
POST1
28.8±25.7
22.1±25.3
−7.1±16.8
−17.0±28.7
8.5 (−0.9 to 18.0)
.077
POST2
25.2±24.9
16.2±19.6
−10.2±21.2
−23.0±31.0
16.3 (0.9–19.7)
.032
POST3
19.3±20.9
13.7±16.8
−17.2±22.8
−25.4±30.3
6.2 (−2.4 to 14.8)
.157
Difficulty score
POST1
18.9±17.7
13.6±15.0
−7.5±11.0
−15.3±17.4
6.8 (1.2–12.3)
.017
POST2
18.6±18.7
12.4±14.4
−7.5±14.7
−16.6±18.4
7.7 (1.4–13.9)
.017
POST3
15.8±17.6
12.0±14.8
−12.5±16.6
−16.9±20.7
4.0 (−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.
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).
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 Measures
Mean Value
Change From Baseline
Treatment Effect (95% CI)
P Value (ANCOVA)
Group CTL
Group IFR
Group CTL
Group IFR
Physical function
POST1
56.8±23.7
58.9±23.8
9.3±18.2
14.9±19.7
4.6 (−3.7 to 12.8)
.277
POST2
58.3±18.9
62.4±23.8
10.0±21.7
18.3±20.3
6.3 (−2.2 to 14.8)
.146
POST3
60.3±20.4
63.8±24.3
13.1±20.1
19.7±22.2
5.3 (−4.0 to 14.6)
.262
Role-physical
POST1
50.7±42.1
44.7±39.9
22.4±41.8
25.7±43.7
−1.9 (−19.5 to 15.8)
.834
POST2
52.7±44.4
69.1±38.3
23.6±54.0
50.0±42.7
18.8 (−0.1 to 37.8)
.052
POST3
72.6±36.1
70.4±37.6
41.9±45.8
51.3±40.7
1.3 (−16.2 to 18.8)
.881
Bodily pain
POST1
57.5±19.4
58.8±22.9
5.6±23.9
14.3±21.8
4.4 (−4.5 to 13.3)
.328
POST2
63.2±22.2
63.6±22.7
10.7±22.5
19.2±25.0
4.0 (−5.6 to 13.6)
.413
POST3
63.6±19.0
63.7±21.4
8.7±23.9
19.2±24.7
3.4 (−6.3 to 13.0)
.489
Social function
POST1
79.3±17.0
78.9±22.9
10.2±20.9
16.4±25.0
2.4 (−5.5 to 6.4)
.549
POST2
78.7±16.6
82.6±20.9
9.5±26.7
20.1±25.8
5.6 (−2.5 to 13.8)
.172
POST3
84.3±16.1
84.9±22.0
13.3±24.4
22.4±26.5
3.2 (−5.5 to 12.0)
.463
Mental health
POST1
80.9±14.4
78.4±16.4
3.8±16.5
7.4±14.2
0.6 (−5.2 to 6.4)
.837
POST2
83.4±12.1
76.3±15.5
6.3±16.7
5.3±15.6
−4.6 (−10.1 to 0.9)
.100
POST3
82.7±14.0
76.4±17.7
5.8±17.6
5.4±20.0
−4.2 (−11.5 to 3.1)
.253
Role-emotional
POST1
93.9±20.3
81.6±34.4
15.8±36.1
9.6±37.9
−10.4 (−22.2 to 1.4)
.083
POST2
94.6±20.1
86.0±30.6
17.1±44.2
14.0±40.7
−7.9 (−19.7 to 3.9)
.188
POST3
93.5±21.8
85.1±33.5
14.0±29.5
13.2±42.1
−6.0 (−8.9 to 6.8)
.350
Vitality
POST1
71.1±14.7
67.4±20.0
7.5±14.0
9.1±13.9
−0.1 (−6.0 to 5.9)
.974
POST2
71.6±12.6
67.9±18.0
7.4±16.9
9.6±13.8
−0.7 (−6.7 to 5.3)
.812
POST3
73.2±14.2
70.1±20.1
9.5±15.1
11.8±17.8
0.0 (−7.4 to 7.3)
.993
General health
POST1
74.8±14.9
71.9±23.2
−2.8±9.7
0.7±17.7
2.1 (−4.4 to 8.6)
.518
POST2
75.9±13.3
73.0±21.0
−2.1±13.1
1.8±15.2
1.7 (−4.5 to 7.8)
.593
POST3
73.6±15.5
75.4±20.4
−3.2±12.8
4.2±14.4
6.0 (−0.5 to 12.4)
.068
PCS
POST1
38.3±9.7
38.8±9.9
3.1±7.8
6.0±9.0
2.2 (−1.6 to 5.9)
.249
POST2
39.3±9.1
42.8±9.3
3.8±9.2
10.0±8.6
4.9 (1.1 to 8.8)
.012
POST3
41.7±7.4
43.6±9.4
6.1±8.3
10.8±10.1
2.9 (−1.0 to 6.9)
.144
MCS
POST1
58.5±7.5
55.7±9.0
3.2±9.0
3.2±8.9
−1.5 (−4.6 to 1.6)
.333
POST2
58.8±5.1
54.8±7.3
3.6±11.4
2.3±9.5
−3.4 (−6.1 to –0.7)
.015
POST3
58.4±7.1
55.0±10.0
2.9±8.3
2.5±11.9
−2.3 (−6.2 to 1.6)
.245
ASHI
POST1
38.5±9.7
38.9±11.0
4.0±9.6
7.7±10.0
2.7 (−1.7 to 7.0)
.271
POST2
40.6±10.0
42.2±10.6
5.8±9.9
11.0±9.9
3.0 (−1.1 to 7.1)
.095
POST3
42.1±8.8
42.5±10.0
6.7±10.9
11.3±10.7
2.0 (−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.
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.
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.
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.
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.
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.
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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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