Volume 87, Issue 8 , Pages 1026-1032, August 2006
Outcomes After Inpatient Rehabilitation of Primary and Revision Total Hip Arthroplasty
Article Outline
Abstract
Vincent KR, Vincent HK, Lee LW, Weng J, Alfano AP. Outcomes after inpatient rehabilitation of primary and revision total hip arthroplasty.
Objective
To compare the outcomes of patients who have gone to inpatient rehabilitation after primary total hip arthroplasty (THA) and revision THA.
Design
Retrospective, comparative study.
Setting
Fifty-bed freestanding, university-affiliated rehabilitation hospital.
Participants
Two hundred fifty-five male and female primary THA patients and 147 male and female revision THA patients.
Intervention
Interdisciplinary inpatient rehabilitation.
Main Outcome Measures
Length of stay (LOS), FIM instrument score and FIM motor score components, hospital charges, and discharge disposition location.
Results
FIM scores improved from admission to discharge by 29.7 and 27.9 points for the primary THA and revision THA groups, respectively (P<.05). LOS was shorter for primary THA patients compared with revision THA patients (10.0d vs 11.5d, P<.05). FIM efficiency (ΔFIM/LOS) was greater for primary THA compared with revision THA (3.4 and 2.7 points/day, P<.05). Total rehabilitation hospital charges were $11,421 and $13,707 for the primary and revision THA groups, respectively, with the mechanical and infection revision THAs incurring the greatest charges ($14,596 and $15,386, respectively; P<.001). Compared with primary THA, revision THA patients were twice as likely to be discharged to locations other than home.
Conclusions
FIM score improvement was lower and LOS and hospital charges were greater in revision THA than in primary THA after rehabilitation. Infection revision THA patients gained less functional independence and were discharged home less often than mechanical or pain revision THA patients; finally, infection and mechanical revision THA accrued the highest hospital charges.
Key Words: Arthroplasty, replacement, hip , Hospital charges , Rehabilitation
TOTAL HIP ARTHROPLASTY (THA) is a highly effective and common treatment for end-stage arthritis of the hip and displaced fracture of the femoral neck.1, 2 Revision THA procedures are more frequently performed because of the limited lifetime of joint components.3 The American Academy of Orthopedic Surgeons estimates that the overall number of hip revision procedures will grow by 20% to 30% over the next 30 years.4 Medically stable primary or revision THA patients are generally discharged to home after 5 to 7 days.5 However, increasingly shorter acute care lengths of stay (LOSs) result in earlier discharge to inpatient rehabilitation facilities6 or discharge to subacute settings. Frequently, patients do not achieve functional milestones before discharge from the acute care setting,7 and more rehabilitation is required during the postacute care stay.8 Lengthy rehabilitation stays are expensive, particularly if complicating comorbidities are present.
Although both primary and revision THA patients make significant gains in function after inpatient rehabilitation,9 inpatient rehabilitation outcomes are influenced by factors such as age and sex.10 Recent data in total knee arthroplasty (TKA) patients showed that revision TKA patients gained less function, had a longer LOS, and were less likely to be discharged home than primary TKA patients. The reason for revision adversely affected outcomes compared with primary TKA, especially infection.11 Similar data regarding the influence of revision status and revision etiology on rehabilitation outcomes in primary and revision THA patients are lacking. Based on these earlier findings,11 we anticipated that all THA patients undergoing inpatient rehabilitation would make gains in physical function but that revision THA patients would make less efficient gains in function, stay longer for rehabilitation, and be less likely to be discharged home than primary THA patients. The purposes of this investigation were (1) to compare the inpatient rehabilitation outcomes of primary and revision THA patients and (2) to determine the effect of documented reasons for revision (mechanical, infection, pain) on inpatient rehabilitation outcomes.
Methods
Participants
The population sample was a convenience sample. All THA cases (N=979) within the University of Virginia (UVA) Clinical Data Repository were collected from January 1, 2002, to January 31, 2006. Men and women composed 42.94% and 57.06% of this population, respectively. Most patients were 65 years or younger (51.09%), 34.67% were between 65 and 80 years, and 14.24% were older than 80 years. Most of the THA patients were white (85.88%) and African American (12.97%). The average acute care LOS before rehabilitation was 4.35 days, with a similar LOS for all age brackets. Eleven percent of patients were discharged home, 42.25% were discharged to inpatient rehabilitation facilities, and the remaining patients were discharged directly to a skilled nursing facility (SNF) (16.30%) or home care or home health services (40.98%). Four patients were discharged to an intermediate care facility, and 6 died within 48 hours of admission for the THA procedure.
From this patient pool, the investigators identified 412 patients admitted to the inpatient rehabilitation facility with diagnoses of THA. Two patients were noted to have bilateral THA and were removed from the analysis so that all patients had unilateral THA. Further, 8 patients (5 primary, 3 revision) were removed from the analysis because they stayed in the rehabilitation facility for only 1 day and were considered by the investigators to represent an inappropriate transfer. Therefore, 402 patients with either primary THA (n=255) or revision THA (n=147) were analyzed in this study. The revision THA patients were further grouped into the following 3 categories based on the major reason for THA revision: mechanical failure THA (n=78), infection-associated THA (n=16), and pain THA (n=53). The reason for THA revision was obtained from the surgeon’s dictated operative note or discharge summary. Before transfer to the rehabilitation facility, all THA patients were assessed by a team consisting of an attending physiatrist and physical and occupational therapists, who considered them to be appropriate candidates for inpatient rehabilitation. This investigation was approved by the Human Investigation Committee at UVA.
Study Design
The design was a retrospective study using data from the medical records of a university-affiliated inpatient rehabilitation hospital.
Population Variables
Patient descriptive variables including age, sex, number and type of comorbidities, height, and weight for each patient at the time of admission were recorded. Weight-bearing status and use of an abductor brace were obtained from the medical record. Physical function was evaluated using the standardized 18-item FIM instrument,12 which comprises 2 motor and cognitive domains. The FIM motor score has been previously used in THA patients to estimate functional ability with activities such as stair stepping, walking, lower-body dressing, mobility with a wheelchair, and transfers.13 The overall FIM motor score and these specific activity measures were used for analysis. The FIM has been previously used and validated in THA patients.9 THA patients have shown more than 20-point improvements during rehabilitation.9
Other criteria selected from the computer database were LOS, total rehabilitation hospital charges, and discharge disposition. Total charges were adjusted for the LOS to generate a cost-per-day variable. As an estimate of the functional gain during the rehabilitation intervention, a FIM efficiency score was reported. FIM efficiency was calculated as the change in FIM from admission to discharge divided by the LOS (ΔFIM/LOS).
Inpatient Rehabilitation Program
All patients completed comprehensive, interdisciplinary inpatient rehabilitation programs at the UVA Rehabilitation Hospital (up to 2wk). Each patient received approximately 3 hours of supervised therapy daily from both physical and occupational therapists. The general rehabilitation program was conducted under the direction of a physiatrist. Therapy sessions were conducted 2 times daily (morning and afternoon sessions) and consisted of both individual and group sessions. During therapy sessions, patients performed activities designed to improve flexibility and range of motion, improve independence in performing activities of daily living, and improve gait, balance, and proprioception. Patients were further instructed on the use of assistive devices for ambulation as dictated by each patient’s individual needs, and all patients were placed on hip precautions on the operated side limiting hip flexion to less than 90°, no internal rotation, and no adduction past midline. In addition, therapy sessions were adapted based on the weight-bearing status or presence of an abduction brace for each individual patient.
Statistical Analyses
Statistical analyses were performed using the SPSS software.a All data are expressed as mean ± standard deviation (SD). For comparisons between primary and revision (2-group comparison, primary THA vs revision THA), the data were analyzed using a 1-way analysis of variance (ANOVA). Comparisons among the primary and revision types (mechanical revision THA, infection revision THA, pain revision THA) were made using a 1-way ANOVA with a Tukey post hoc test. A repeated-measures ANOVA was performed on total FIM, FIM motor, and individual FIM components from admission to discharge. The dependent variable was the FIM score, with the group factor (primary THA, mechanical revision THA, infection revision THA, pain revision THA) and time (admission, discharge). A Tukey post hoc test was used to determine where group differences occurred. Given that there was a significant difference between groups for admission FIM scores, an analysis of covariance (ANCOVA) was performed to evaluate discharge FIM scores for the 2- and 4-group models. Admission FIM scores were used as the covariate, and the predicted means generated by the ANCOVA were analyzed using a 1-way ANOVA with a Tukey post hoc test. Univariate ANOVA was used to examine the potential interaction of group membership (primary THA vs revision THA) and either weight-bearing status or abductor brace use on outcome variables.
Because of different sample sizes in the 4-group model, differences in comorbidities, weight-bearing status, abductor brace use, and discharge disposition were analyzed with a nonparametric test, the Kruskal-Wallis test. Given that weight-bearing status might influence FIM gains during rehabilitation, each study variable was also separately analyzed by weight-bearing status, classified as full weight bearing (as tolerated), partial weight bearing, and non–weight bearing. Only 2 patients in the study (primary THA group) were “non–weight bearing,” so these 2 patients were excluded from this specific analysis. The potential interaction of study group (primary THA, revision THA) and weight-bearing status was analyzed with a univariate ANOVA.
Pearson correlations were performed between FIM efficiency scores and variables that may be related to this variable (age, sex, discharge living setting, number of comorbidities). A priori α levels were set at .050 for all statistical tests. Using a Bonferroni adjustment to adjust for multiple comparisons, the α level was set at .0125.
Results
Participant Characteristics
There were no significant differences between groups for any of the demographic variables or for weight-bearing status (1-way ANOVA, P>.05) (table 1). Table 1 presents subject characteristic data for all the primary and revision THA groups. The number of comorbidities was similar between the primary and revision THA groups (P>.05).
Table 1. Subject Characteristics of Primary and Revision THA Patients (N=402)
| Characteristics | Primary THA (n=255) | Revision THA (n=147) |
|---|---|---|
| Men, n (%) | 91 (37) | 48 (33) |
| Women, n (%) | 154 (63) | 99 (67) |
| Age (y) | 70.7±9.9 | 71.1±11.3 |
| Height (cm) | 165.1±24.8 | 166.0±12.6 |
| Weight (kg) | 83.2±21.8 | 84.1±17.3 |
| Body mass index (kg/m2) | 29.6±6.9 | 30.3±6.0 |
| Ethnicity (%) | ||
 White | 87.3 | 79.3 |
| African American | 8.6 | 18.3 |
| Asian | 3.3 | 1.2 |
| Weight-bearing status (%) | ||
| Full | 60.1 | 54.5 |
| Partial | 39.5 | 40.9 |
| Non–weight bearing | 0.4 | 4.5 |
| Abductor brace (%) | 10.3 | 10.0 |
| Smoker (%) | 18.0 | 0.0 |
| Alcohol use (%) | 29.3 | 20.0 |
| Comorbidities (n) | 7.7±1.6 | 8.2±1.1 |
| Comorbidities (%) | ||
| Hypertension | 69.3 | 81.8 |
| Anemia | 42.9 | 36.4 |
| Hyperlipidemia | 25.2 | 18.2 |
| Esophagitis | 18.9 | 13.6 |
| Coronary artery disease | 13.9 | 13.6 |
| Diabetes mellitus | 13.9 | 9.1 |
| Hypothyroid | 12.6 | 13.6 |
| Depression | 11.8 | 15.0 |
| Rheumatoid arthritis | 2.1 | 4.5 |
| Gout | 2.9 | 4.5 |
Functional Outcomes
FIM scores are presented in table 2. Admission FIM scores were 6% lower for the revision THA than the primary THA group (1-way ANOVA, P<.05). Among the primary group and revision subgroups, admission FIM scores were lower in the infection revision THA and mechanical revision THA groups than in the primary THA group (1-way ANOVA, P<.001). After inpatient rehabilitation, FIM scores for all groups were significantly greater (repeated-measures ANOVA, P<.05). Overall, the discharge FIM was higher in the primary THA than the revision THA group by 6% (ANCOVA, P<.001). Discharge FIM scores were higher for the primary THA group than for the 3 revision THA subgroups by 5% to 12% (ANCOVA, P<.001). Among the revision subgroups, the discharge FIM scores were 7% lower for the infection revision THA group when compared with the mechanical revision and pain revision THA groups (ANCOVA, P<.05). Among the primary group and THA revision subgroups, the change in FIM was 5.5% lower for the infection revision THA group compared with the primary THA group (1-way ANOVA, P<.05).
Table 2. FIM Scores and Outcomes and Changes in Outcome Measures From Admission to Discharge During Inpatient Rehabilitation for Primary and Revision THA Patients (N=402)
| Measures | Primary THA | Revision THA | Revision THA Subgroups | ||
|---|---|---|---|---|---|
| All Patients | Mechanical Revision THA | Infection Revision THA | Pain Revision THA | ||
| Admission FIM score | 78.7±9.4 | 74.0±11.7⁎ | 74.1±12.3⁎ | 70.9±10.6⁎ | 74.8±11.1 |
| Discharge FIM score | 108.4±9.6 | 101.9±16.2§ | 102.4±13.8§ | 95.2±18.3∥ | 103.2±18.6§ |
| Raw change in FIM score | 29.8±8.3 | 27.9±11.9 | 28.3±9.9 | 24.3±11.5⁎ | 28.4±14.6 |
| Change in FIM score (%) | 38.9±14.5 | 38.8±19.1 | 39.9±17.8 | 34.0±16.6 | 38.6±21.5 |
| LOS (d) | 10.0±4.2 | 11.5±5.3⁎ | 12.3±6.0⁎† | 13.1±4.5 | 9.8±3.8 |
| ΔFIM/LOS (points gained/d) | 3.4±1.5 | 2.7±2.2⁎ | 2.7±1.4 | 2.0±1.1⁎† | 3.1±3.2 |
| Total cost ($) | 11,421±5693 | 13,707±6982⁎ | 14,596±7832⁎ | 15,386±7051⁎† | 11,817±5132 |
| Cost per day ($) | 1151±300 | 1236±290⁎ | 1180±160 | 1461±558‡ | 1233±256⁎ |
⁎ Different from primary THA at P<.05 (1-way ANOVA). |
† Different from pain revision THA at P<.05 (1-way ANOVA). |
‡ Different from primary THA, pain revision THA, and mechanical revision THA at P<.05 (1-way ANOVA). |
§ Different from primary THA at P<.05 (ANCOVA). |
∥ Different from primary THA, pain revision THA, and mechanical revision THA at P<.05 (ANCOVA). |
FIM Motor Scores
The raw scores for several FIM motor score components that involve weight bearing are reported in table 3. The overall FIM motor scores at discharge and change from admission were 22% and 7.2% lower in the infection revision THA and primary THA groups, respectively (P<.05). Shower transfer and lower-body dressing scores at admission were 55% and 14% lower in the mechanical revision THA and primary THA groups, respectively (P<.05). The overall changes in these FIM motor component scores from admission to discharge were similar among all groups, however. Only the change in the walking assistance score was significantly lower in the infection revision THA group versus all other groups (P<.05).
Table 3. Scores of Select FIM Motor Score Components That Involve Lower-Extremity Activity at Admission and Discharge
| FIM Component | Primary THA | Mechanical Revision THA | Infection Revision THA | Pain Revision THA |
|---|---|---|---|---|
| Overall FIM motor score | ||||
| Admission | 42.9±7.5 | 38.8±8.0 | 35.0±6.4 | 39.7±8.5 |
| Discharge | 68.5±9.1 | 65.3±9.9 | 53.5±11.2§ | 64.6±14.3 |
| Change | 25.7±8.5 | 26.5±8.2 | 18.5±5.4 | 24.9±11.9 |
| Bed–to-chair transfer | ||||
| Admission | 3.5±0.9 | 3.3±1.1 | 3.0±0.8 | 3.5±0.9 |
| Discharge | 5.7±0.8 | 5.6±0.8 | 5.0±0.8 | 5.5±1.2 |
| Change | 2.2±1.0 | 2.4±1.1 | 2.0±1.0 | 2.0±1.2 |
| Shower transfer | ||||
| Admission | 1.8±1.9 | 0.8±1.5‡ | 2.0±2.3 | 2.0±2.0 |
| Discharge | 5.2±1.5 | 4.3±2.0⁎ | 3.3±2.6 | 4.9±1.9 |
| Change | 3.4±2.1 | 3.5±2.2 | 1.3±0.5 | 2.9±2.4 |
| Toilet transfer | ||||
| Admission | 3.8±0.9 | 3.4±1.1 | 3.0±0.8 | 3.6±1.1 |
| Discharge | 5.7±0.8 | 5.5±0.8 | 5.3±1.0 | 5.4±1.2 |
| Change | 1.9±0.9 | 2.1±1.2 | 2.3±0.5 | 1.8±1.2 |
| Stairs | ||||
| Admission | 0.5±1.3 | 0.4±1.1 | 0.3±0.5 | 0.3±0.3 |
| Discharge | 4.2±2.0 | 3.5±2.1 | 2.0±2.0 | 4.2±2.1 |
| Change | 3.7±2.1 | 3.1±2.1 | 1.8±1.5 | 3.9±2.1 |
| Lower-body dressing | ||||
| Admission | 2.8±1.0 | 2.4±1.0⁎ | 2.5±1.3 | 2.6±1.2 |
| Discharge | 5.4±1.1 | 5.0±1.3 | 4.3±0.5 | 5.0±1.5 |
| Change | 2.6±1.2 | 2.6±1.3 | 1.8±1.3 | 2.4±1.5 |
| Walking assistance | ||||
| Admission | 1.8±1.3 | 1.3±1.0 | 1.3±0.5 | 1.4±0.6 |
| Discharge | 5.4±1.4 | 5.3±1.5 | 2.8±2.2 | 5.4±1.2 |
| Change | 3.6±1.6 | 4.0±1.5 | 1.5±2.4† | 4.1±1.3 |
| Distance walked∥ | ||||
| Admission | 1=52, 2=34, 3=12 | 1=63, 2=25, 3=4 | 1=75, 2=25, 3=0 | 1=70, 2=30, 3=0 |
| 3% missing | 8% missing | 0% missing | 0% missing | |
| Discharge | 1=4, 2=10, 3=85 | 1=8, 2=10, 3=81 | 1=25, 2=50, 3=25 | 1=3, 2=13, 3=80 |
| 1% missing | 0% missing | 0% missing | 3% missing |
⁎ Different from primary THA at P<.05 (1-way ANOVA). |
† Different from primary THA, pain revision THA, and mechanical revision THA at P<.05 (1-way ANOVA). |
‡ Different from primary THA, pain revision THA, and infection revision THA at P<.05 (ANOVA). |
§ Different from primary THA at P<.05 (ANCOVA). |
∥ Distance walked was determined whether the patient walked <15.2m (1), 15.2–45.4m (2), or >45.4m (3); data are expressed as percentage of the group in each walking category. |
FIM Efficiency
The FIM efficiency scores were greater for the primary THA compared with the revision THA group (1-way ANOVA, P<.05). The FIM efficiency score was lower in the infection revision THA group compared with the primary and pain revision THA groups by 41% and 35%, respectively (1-way ANOVA, P<.05) (see table 2).
Length of Stay
The LOS was shorter for the primary THA compared with the revision THA group by 1.5 days (1-way ANOVA, P<.05). Among the 4 groups, the mechanical revision THA group had a significantly longer LOS than the primary and pain revision THA groups (1-way ANOVA, P<.01) (see table 2).
Total Rehabilitation Hospital Charges
Total rehabilitation hospital charges were 20% higher for the revision THA compared with the primary THA group (1-way ANOVA, P<.001) (see table 2). Among the primary group and revision subgroups, the total hospital charges were 28% to 35% higher for the mechanical revision and infection revision THA groups when compared with primary THA (1-way ANOVA, P<.001). Costs per day were 7% higher in the revision THA than primary THA group (1-way ANOVA, P<.001) (see table 2). Among the primary and revision subgroups, daily costs were 7% to 28% higher in pain revision and infection revision THA compared with primary THA (1-way ANOVA, P<.001) (see table 2).
Discharge Disposition
Eight percent more patients were discharged to home from the primary THA group compared with the revision THA group (Kruskal-Wallis test, P<.001) (fig 1A). Further, when compared with primary THA, revision THA had greater rates of discharge to SNFs and acute transfer back to the main hospital (Kruskal-Wallis test, P<.001). When analyzed by revision subgroup, 26% to 29% more of the mechanical revision and of the pain revision THA patients went home compared with infection revision THA patients (see fig 1B). Compared with pain revision and mechanical revision THA, 29% to 32% more infection revision THA patients were discharged to an SNF or were transferred back to the acute care hospital (see fig 1B). Only in the mechanical revision THA group were any patients discharged to assisted living (n=2).
Fig 1.
Discharge living setting in primary and revision THA patients. (A) Percentage of patients discharged to home, SNF, acute transfer back to the hospital, or assisted living in primary and revision THA after inpatient rehabilitation. (B) Percentage of patients discharged to respective living settings in revision THA subgroups. Abbreviations: IRTHA, infection revision THA; MRTHA, mechanical revision THA; PRTHA, pain revision THA; PTHA, primary THA; RTHA, revision THA.
Weight-Bearing Status and Abductor Brace Use
Equal proportions of patients had either full or partial weight bearing in primary and revision THA (Kruskal-Wallis test, P>.05). Weight-bearing status did not influence any of the functional outcomes or hospital costs examined in this investigation for primary and revision THA patients (1-way ANOVA, P>.05) (table 4). No significant interactions were found between group and weight-bearing status for any outcome variable.
Table 4. Changes in FIM Scores, FIM Motor Scores, LOS, ΔFIM/LOS, and Hospital Charges During Inpatient Rehabilitation for Patients Based on Weight-Bearing Status and Abductor Brace Use (N=402)
| Measures | Full Weight Bearing | Partial Weight Bearing | Abductor Brace Present | Abductor Brace Absent |
|---|---|---|---|---|
| Admission FIM score | 77.0±11.0 | 78.1±10.1 | 72.5±9.0⁎ | 77.9±10.8 |
| Discharge FIM score | 106.7±12.4 | 106.4±13.2 | 100.5±15.6⁎ | 107.0±12.6 |
| Change in FIM score | 30.2±8.4 | 28.3±9.9 | 28.0±9.8 | 29.5±9.2 |
| FIM motor score | ||||
| Admission | 42.5±8.2 | 43.0±7.1 | 38.1±6.6⁎ | 43.1±7.9 |
| Discharge | 68.2±10.3 | 67.8±9.8 | 62.7±12.3⁎ | 68.5±10.0 |
| LOS (d) | 10.0±4.3 | 10.1±4.6 | 10.5±4.3 | 10.0±4.5 |
| ΔFIM/LOS (points gained/d) | 3.3±1.4 | 3.0±2.2 | 3.2±1.7 | 3.2±1.8 |
| Total cost ($) | 11,399±5344 | 11,226±6089 | 13,768±7040⁎ | 11,187±5471 |
| Cost per day ($) | 1130±213 | 1184±256 | 1172±199 | 1150±237 |
⁎ Different from abductor brace absent at P<.05 (1-way ANOVA). |
Patients who wore abductor braces had 6% lower admission and discharge FIM scores than those who did not (ANCOVA, P<.05). Total hospital charges were 19% higher in patients using abductor braces compared with those who did not (1-way ANOVA, P<.05) (see table 4).
Discussion
This study examined the effect of revision status and reason for revision on inpatient rehabilitation outcomes after THA. Although some of these findings may be considered clinically intuitive, these have not yet been quantified in the scientific literature. There were 3 major findings of this study. First, revision THA requires a more lengthy (and costly) inpatient stay than primary THA. Second, the infection revision group accrued greater total hospital costs and had the lowest FIM efficiency (and did not improve in overall FIM motor score and walking ability) than all other groups. The pain revision group had a longer LOS, whereas the pain revision and infection revision THA groups incurred the highest daily costs among all groups. Abductor brace use was associated with higher hospital charges and lower FIM scores, whereas weight-bearing status was not.
Functional Improvement
In the present investigation, FIM scores increased by 29.8 and 27.9 points in the primary and revision THA groups, respectively (table 5), similar to data reported by the Uniform Data System for Medical Rehabilitation’s national databaseb (by 18–28 points).9, 14, 15, 16, 17 FIM efficiency scores for primary THA are similar to what was previously reported (FIM efficiency, 3.37)9 and lower for those patients after revision THA. Among the specific FIM motor components, walking independence and overall FIM motor scores were lowest in the infection revision THA versus the remaining groups. Admission shower transfer and lower-body dressing scores were lowest in the mechanical revision THA group. To our knowledge, there are no comparative data regarding FIM scores or specific FIM motor scores between primary and revision hip arthroplasty patients in the inpatient rehabilitation hospital. FIM efficiency correlated with admission FIM score and discharge living setting (table 5). This finding suggests that patients starting at a lower functional level are more likely to have reduced FIM efficiency and more likely to be discharged to a setting other than home.
Table 5. Correlations (r) Between FIM Efficiency Scores and Population Variables
| Variables | r | Significance (P) |
|---|---|---|
| Sex | −.066 | .232 |
| Age | −.059 | .236 |
| Discharge living setting | −.410 | <.001⁎ |
| Number of comorbidities | .006 | .918 |
| FIM score at admission | .250 | <.001⁎ |
⁎ Significant after Bonferroni adjustment. |
Revision THA patients might be tentative during therapy because they fear another joint replacement failure. Degenerative processes, such as osteolysis and aluminum toxicity,18 may necessitate a revision THA because of tissue damage that compromises bone–component interface integrity.19 We speculate that there may be excessive tissue damage to counteract these degenerative processes (eg, cement fragments in the surgical area, periprosthetic femoral fractures)20, 21 or tissue loss (eg, bone reaming with acetabular infection, use of specific saw blades)22 that occurs with specific surgical revision approaches for mechanical or infection reasons. These procedures could cause significant hip pain and stiffness and lead to a lengthy LOS and low FIM gain. Infection revision THA patients have reduced FIM efficiency compared with patients admitted with mechanical or pain etiologies. A potential explanation is that some infection revision THA patients are disrupted during their inpatient rehabilitation programs for administration of intravenous antibiotics, preventing full use of therapy time.
Surprisingly, weight-bearing status did not influence any of the outcomes measured in this population sample. At this institution, increasingly more patients are instructed by the orthopedic surgeons to wear abductor braces to reduce the likelihood of dislocation postsurgery. We suggest that these braces may limit motion and impede functional improvement during rehabilitation. Abductor brace use did influence admission and discharge FIM scores and total hospital charges, but not FIM efficiency and FIM gains. The reduction in physical function secondary to abduction brace may hamper a patient’s ability to live independently, increasing the likelihood of being discharged to a location other than home. Abductor brace use should be weighed against the clinical concern for increased potential for hip dislocation, particularly in patients without a prior history of such dislocations.
LOS and Total Rehabilitation Charges
Hip arthroplasties, particularly revision THA, are complex and traumatic and may cause significant blood loss.5 Revision THA rehabilitation programs are also more complex and lengthier than those of primary THA. The average LOS for our primary and revision THA patients was 10.0 and 13.1 days, respectively, similar to that reported in the literature.9 The reason for these group differences is not clear. One explanation could be that once pain control is achieved in the rehabilitation hospital, revision patients can successfully engage in therapies that foster FIM gains and LOS similar to primary THA.
Total Charges
Reimbursement for inpatient rehabilitation after THA does not take into account whether the THA was primary or revision. Revision THA was associated with $2300 of additional rehabilitation hospital charges versus primary THA. All revision subgroups accrued greater total costs than the primary THA group; these costs were likely due to several sources including intravenous antibiotics, additional care for infection management, and medications for pain management. Lengthier LOS in revision THA may be due to the extra combined care of the physicians, nurses, therapists,23 and support staff and the hospital boarding fees. Further research is warranted to identify strategies to normalize LOS and lower hospital costs among different THA etiologies.
Discharge Disposition
Compared with primary THA patients, revision THA patients were less likely to be discharged to home and were 1.96 times as likely to be discharged to an SNF. The reason for the differences between the 3 revision groups regarding discharge disposition is not clear. A difference in demographics seems unlikely given that all groups were similar in age, sex composition, and number of comorbidities. A striking finding in this study was the low discharge-to-home rate for the infection revision THA group. One third of infection revision THA patients were discharged to an SNF, and 16.7% were transferred back to the hospital. This might have been due to the need for long-term, complex infection management that patients or caretakers could not perform or pay for at home.
Conclusions
Both primary and revision THA patients derived benefit from participating in inpatient rehabilitation; however, revision status influences rehabilitation outcomes. Revision THA (especially infection revision THA) patients will likely require placement in a living situation outside the home. This awareness can assist in appropriate patient referral to other facilities such as SNFs or for advanced planning and preparation for discharge. Rehabilitation outcomes were not affected by weight-bearing status but were negatively affected by the use of an abductor brace.
Suppliers
Acknowledgments
The contents of this project are solely the responsibility of the authors and do not necessarily represent the official views of the National Center for Complementary and Alternative Medicine or the National Institutes of Health. We sincerely appreciate the assistance from Tom Cook, Lori Aylor, and Jennifer Martin with database access.
References
- The effect of elective total hip replacement on health-related quality of life . J Bone Joint Surg Am . 1993;75:1619–1626
- . Total hip arthroplasty (optimal treatment for displaced femoral neck fractures in elderly patients) . Clin Orthop Relat Res . 2004;429:43–48
- . 2001 National Hospital Discharge Survey . Adv Data . 2003;332:1–20
- . Primary, revision THA, TKA expected to surge by 2030 . 2006; Academy News [online newsl]. March 22, Available at: http://www.aaos.org/wordhtml/acadnews/2006news/sat/c25_2.htm. Accessed March 31, 2006.
- . Hospital resource utilization for primary and revision total hip arthroplasty . J Bone Joint Surg Am . 2005;87:570–576
- . Decreasing length of stay after total joint arthroplasty (effect on referrals to rehabilitation units) . Arch Phys Med Rehabil . 1999;80:192–194
- . The day of discharge after total hip arthroplasty and the achievement of rehabilitation functional milestones (11-year trends) . J Arthroplasty . 2003;18:453–457
- . Rehabilitation of orthopedic and rheumatologic disorders. 3. Total hip arthroplasty rehabilitation . Arch Phys Med Rehabil . 2005;86(3 Suppl 1):S56–S60
- . Inpatient interdisciplinary rehabilitation after total hip arthroplasty surgery (a comparison of revision and primary total hip arthroplasty) . Arch Phys Med Rehabil . 2001;82:129–133
- . Sex and age effects on outcomes of total hip arthroplasty after inpatient rehabilitation . Arch Phys Med Rehabil . 2006;87:461–467
- . Inpatient rehabilitation outcomes in primary and revision total knee arthroplasty patients . Clin Orthop Relat Res . 2006;May(446):201–207
- . A validation of the functional independence measurement and its performance among rehabilitation inpatients . Arch Phys Med Rehabil . 1993;74:531–536
- . Effect of activities of daily living on fiber type atrophy of the vastus lateralis muscle in patients with joint disorders . Am J Phys Med Rehabil . 1998;77:122–127
- . Functional independence measure versus short form-36 (relative responsiveness and validity) . Int J Rehabil Res . 2001;24:65–68
- . Functional gains and therapy intensity during subacute rehabilitation (a study of 20 facilities) . Arch Phys Med Rehabil . 2002;83:1514–1523
- . A validation of the functional independence measurement and its performance among rehabilitation inpatients . Arch Phys Med Rehabil . 1993;74:531–536
- . Improved satisfaction during inpatient rehabilitation after hip and knee arthroplasty (a retrospective analysis) . Am J Phys Med Rehabil . 2001;80:798–803
- . Ionogran in revision arthroplasty . J Bone Joint Surg Br . 2000;82:192–199
- . Early failure in total hip arthroplasty . Clin Orthop Relat Res . 2006;Jun(447):76–78
- . The histological appearance of the periprosthetic capsule in failed total hip arthroplasty differs depending on the presence of polyethylene acetabulum destruction, iliac bone damage and presence of infection . Pol J Pathol . 1996;47:19–25
- . The management of periprosthetic femoral fractures around hip replacements . Injury . 2003;34(2):95–105
- . Removal of well-fixed, cementless, acetabular components in revision hip arthroplasty . J Bone Joint Surg Br . 2003;85:949–952
- . An analysis of the relationship between the utilization of physical therapy services and outcomes of care for patients after total hip arthroplasty . Phys Ther . 2000;80:448–458
Supported in part by the National Center for Complementary and Alternative Medicine, National Institutes of Health (grant no. T32-AT00052) and by the American Geriatrics Society (Jahnigen Career Development Grant).No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.
PII: S0003-9993(06)00397-2
doi:10.1016/j.apmr.2006.04.015
© 2006 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.
Volume 87, Issue 8 , Pages 1026-1032, August 2006
