Early Inpatient Rehabilitation After Elective Hip and Knee Arthroplasty (2024)

Context.—Inpatient rehabilitation after elective hip and knee arthroplasty isoften necessary for patients who cannot function at home soon after surgery,but how soon after surgery inpatient rehabilitation can be initiated has notbeen studied.

Objective.—To test the hypothesis that high-risk patients undergoing elective hipand knee arthroplasty would incur less total cost and experience more rapidfunctional improvement if inpatient rehabilitation began on postoperativeday 3 rather than day 7, without adverse consequences to the patients.

Design.—Randomized controlled trial conducted from 1994 to 1996.

Setting.—Tertiary care center.

Participants.—A total of 86 patients undergoing elective hip or knee arthroplastyand who met the following criteria for being high risk: 70 years of age orolder and living alone, 70 years of age or older with 2 or more comorbid conditions,or any age with 3 or more comorbid conditions. Of the 86 patients, 71 completedthe study.

Interventions.—Random assignment to begin inpatient rehabilitation on postoperativeday 3 vs postoperative day 7.

Main Outcome Measures.—Total length of stay and cost from orthopedic and rehabilitation hospitaladmissions, functional performance in hospitals using a subset of the functionalindependence measure, and 4-month follow-up assessment using the RAND 36-itemhealth survey I and the functional status index.

Results.—Patients who completed the study and began inpatient rehabilitationon postoperative day 3 exhibited shorter mean (±SD) total length ofstay (11.7±2.3 days vs 14.5±1.9, P<.001),lower mean (±SD) total cost ($25891±$3648 vs $27762±$3626, P<.03), more rapid attainment of short-term functionalmilestones between days 6 and 10 (36.2±14.4 m ambulated vs 21.4±13.3m, P<.001; 4.8±0.8 mean transfer functionalindependence measure score vs 4.3±0.7, P<.01),and equivalent functional outcome at 4-month follow-up.

Conclusion.—These data showed that high-risk individuals were able to tolerate earlyintensive rehabilitation, and this intervention yielded faster attainmentof short-term functional milestones in fewer days using less total cost.

TOTAL JOINT replacements for the hip and knee are among the most commonsurgical procedures in the United States. Rehabilitation is essential to minimizedisability after surgery, yet pressure on clinicians to reduce length of stayhas limited the use of hospital rehabilitation services. Most patients canbe discharged directly home in 5 to 7 days if they are medically stable andhave completed a postoperative rehabilitation program.¹Those who were significantly older, lived alone, and had an increased numberof comorbid conditions were at high risk for requiring further inpatient rehabilitationservices before returning home.² However, thereare no practice parameters to determine how best to treat high-risk patientswho are unable to go directly home after joint replacement surgery.

Two factors that influence the type of rehabilitation program selectedfor high-risk individuals include the timing of when to begin inpatient rehabilitationand the intensity of therapy services needed to attain good outcomes. Somerehabilitation facilities accept patients as early as the third postoperativeday to reduce patients' length of stay. However, it is unknown if elderlypatients can benefit from intensive therapy this early after surgery. If patientsare transferred to a rehabilitation facility prematurely, rehabilitation costscould be increased if patients are unable to participate in intensive physicaland occupational therapies, or if they are transferred out of rehabilitationbecause of acute medical or surgical complications. It has not been determinedif more intensive therapy for high-risk joint replacement patients producesa faster rate of improvement, or if outcome is independent of the amount ofdelivered therapy.³

Using an acute inpatient rehabilitation setting, this study randomizedhigh-risk patients to either begin inpatient rehabilitation on postoperativeday 3 (day 3 treatment group) or to delay inpatient rehabilitation until 7days after surgery (day 7 treatment group). Since the acute care hospitalprovides some rehabilitation services at a lower intensity compared with inpatientrehabilitation, and most patients who go home can be discharged within 7 days,this time interval was used as the control. Total length of stay, total cost,complications, and functional outcomes were measured. We tested the hypothesisthat the day 3 group would demonstrate less total cost and a faster rate offunctional improvement because intensive therapy was delivered earlier aftersurgery. Additionally, we hypothesized that beginning rehabilitation effortsearlier following surgery would not be detrimental to long-term outcomes.

All patients evaluated for total-hip arthroplasty or total-knee arthroplastyat the University of Pittsburgh orthopedics office were considered for inclusionbetween August 1994 and November 1995. Eligible subjects included patientsat high risk for requiring inpatient rehabilitation after elective hip andknee arthroplasty: (1) 70 years of age or older and living alone, (2) 70 yearsof age or older with 2 or more comorbid conditions, or (3) any age with 3or more comorbid conditions.² A comorbiditychecklist that assessed 11 major conditions was developed to extract significantmedical history from both the clinical record and patient interviews. Thesurgical procedure could be a primary arthroplasty or a revision of a previousarthroplasty. Individuals were excluded if the indication for surgery includedstabilization for tumor, acute fracture, femoral osteonecrosis, or hemophilicarthropathy. Additionally, patients were excluded if medical or surgical complicationsoccurred postoperatively and precluded scheduled rehabilitation transfer.Each patient who met the criteria for inclusion read and signed the institutionalreview board informed consent form before data collection began.

Eighty-six subjects met the inclusion criteria. These patients wereassigned randomly to begin inpatient rehabilitation on postoperative day 3(day 3 group) or remain on the orthopedic service until postoperative day7 (day 7 group) and then pursue inpatient rehabilitation. A random listingof 100 numbers, using 0 to equal day 3 group and 1 to equal day 7 group, wasgenerated in blocks of 10. Separate lists were used for hip and knee patientsto maintain balance of the randomized design. The codes were administeredby a blinded executor who kept them in a locked filing cabinet that was inaccessibleto the principle investigator and research coordinator. Randomization occurredpreoperatively in the orthopedic office after patient eligibility was establishedand the consent form was signed. Based on our previous data,²a sample size of 40 patients per group was determined to have adequate statisticalpower (β=.80) to detect major effect sizes (SD=0.8) for length of stayand total costs.

Patients were treated at a university medical center for all aspectsof the study, which included an orthopedic surgery floor and a 20-bed inpatientrehabilitation unit. Patients in the day 3 group had earlier exposure to theinpatient rehabilitation unit, even though both treatment groups started therapyat the same time.

While in the acute care orthopedic surgery service, patients were scheduledto receive two 30-minute physical therapy sessions beginning on postoperativeday 2 and one 30-minute occupational therapy session beginning no later thanpostoperative day 3 during weekdays only. The comprehensive inpatient rehabilitationprogram included two 60-minute physical therapy and two 60-minute occupationaltherapy sessions daily, as well as recreational therapy and clinical psychologyservices as needed. One 30-minute physical therapy session was given to allpatients, regardless of location, on Saturday.

The rehabilitation and orthopedic units both used clinical pathways,and several practical considerations were routinely used. Pain was aggressivelytreated with ice packs applied to the incision, and narcotic analgesia wasalways given before morning and afternoon therapy sessions. The surgical woundwas monitored for drainage and prophylactic antibiotic coverage with a first-generationcephalosporin instituted when needed, although therapy was infrequently withheldbecause of wound drainage. Discharge from the rehabilitation unit was determinedby the interdisciplinary team of clinicians, some of whom were not blindedto randomization. However, standardized, objective criteria were used fordischarge. All patients had to be ambulating greater than 45 m, performingtransfers and all self-care independently with adaptive equipment, and demonstratingthe ability to safely return home.

Length of Stay and Cost Analysis. The total hospital length of stay, which included the days in the orthopedicand rehabilitation units, was compared between treatment groups. All physicaland occupational therapy sessions were counted throughout the orthopedic andrehabilitation admissions. Data were collected by the Medical Archival System(MARS) database.⁴

Charges were retrieved from the individual transaction detail, includingtransaction code, department code, quantity, date of service, and charge.Charge data were converted to cost using total-loaded ratios of cost to charge,which are hospital-specific, government-mandated standards used to estimatecost in prior joint replacement studies.^5,6The ratios of cost to charge have been shown to have good reliability forcomparing the relative costs of patients with the same diagnosis in differentinstitutions.⁷ Each department's unique fiscalyear 1995 ratios of cost to charge were applied to arrive at the total-loadedcost for each transaction. The total-loaded costs were aggregated to arriveat the department costs for day-of-surgery costs, hospital postoperative costs,and rehabilitation costs for physical and occupational therapy. Physiciancosts were derived from average Medicare reimbursem*nt for the type of surgicalprocedure and physiatric evaluation and management.

Functional and Health Status Assessments. Baseline data were obtained approximately 4 weeks before surgery toassess general health status and function. General health status was obtainedwith the RAND 36-item health survey I (RAND-36) and data were confined to2 primary health constructs, physical and mental domains.^8,9The functional status index (FSI)¹⁰ was usedto assess overall function based on important tasks that are needed to completeactivities of daily living. The FSI has 3 dimensions that measure difficulty,pain, and assistance. Both of these self-report instruments have been validatedin prior hip and knee arthroplasty studies.^11-13

A subset of the functional independence measure (FIM)¹⁴was used daily in both the orthopedic and rehabilitation units to measureimmediate postoperative function. The therapists in the study were trainedto use the FIM, and we have previously demonstrated excellent interrater reliabilityusing a FIM-based measurement system in the acute care hospital after jointreplacement.¹⁵ To assess the perceived benefitof the rehabilitation program, follow-up data using the RAND-36 and FSI weremailed at 16 weeks¹⁶ from the date of hospitaldischarge.

Data Analyses. Analysis of variance, using the general linear model because of unequalsample sizes, was used for length of stay and cost data. To provide betterprotection against type I error, a multivariate analysis of variance (MANOVA)approach was used to analyze RAND-36 and FSI change scores. Repeated-measuresMANOVA was used for the FIM data that were divided into 3 periods. Power orsquare-root transformations were applied to 3 variables to achieve adequatenormality for the analysis of variance and MANOVA analyses. Raw means andSDs for all variables are reported here for clarity. Exact probability χ² analyses, computed with the StatXact program,¹⁷were used to analyze dichotomous and ordinal measures. A P value of <.05 was used as statistically significant, and Bonferronicorrection was applied to post hoc analyses when the primary analyses weresignificant.

The intention-to-treat principle was maintained in this study wheneverpossible. Because of differences in study dropouts between the day 3 and day7 groups, efficacy analyses that included only subjects completing the rehabilitationarm of the study also were computed for length of stay and cost data.

Of the 86 patients randomized to the study, 71 patients (83%) completedthe rehabilitation arm of the study following replacement surgery (Table 1). Fifteen patients were excludedor dropped out after surgery (Table 2),with no exclusions occurring before randomization. The number of patient exclusionswas not significantly different between the 2 rehabilitation conditions (χ² [1 df]=0.47, P=.57).A MANOVA analysis between those excluded and those completing treatment forFSI and RAND-36 presurgery scores indicated no significant differences. Analysisof variance data indicated no significant differences with respect to ageand the number of comorbid conditions, and χ² analyses indicatedno significant differences with respect to gender.

As displayed in Table 1,the baseline characteristics for subjects completing the rehabilitation componentwere similar between the 2 treatment conditions (day 3 vs day 7) and the 2types of replacement surgeries (hip vs knee). Analysis of variance and χ² analyses for the variables listed in Table 1 indicated that for knee patients, a higher proportion ofrheumatoid arthritis patients were randomized to the day 3 group (χ² [1df]=4.92, P<.05).For all other pretreatment measures, no significant differences were foundbetween groups, indicating that the randomization procedure was successfulin producing comparable groups.

Both intention-to-treat and efficacy analyses of total length-of-staydata indicated that patients assigned to the day 3 protocol stayed in thehospital significantly fewer days than day 7 patients (both with P<.04). This conclusion was not significantly influenced or modifiedby the type of replacement received. The length-of-stay data for patientswho completed rehabilitation are presented in Table 3. When dropouts were included, patients assigned to day 3had a mean length of stay of 11.9 days (SD, 2.9) and day 7 had 13.8 days (SD,3.1), which remained significantly different (P<.004).The slight reduction in length-of-stay differences between day 3 and day 7patients when dropouts were included is because of the longer stay of excludedday 3 patients compared with those day 3 patients completing rehabilitation,coupled with the 4 patients in the day 7 dropout group (Table 2) who stayed an average of only 8.5 days because they electedto go home rather than complete the rehabilitation component of the study.

Intention-to-treat grand total cost analyses indicated no significantdifferences between patients assigned to the day 3 and day 7 treatment conditions.Day 3 patients had a mean cost of $26582 (SD, $4370) and day 7 had a meancost of $26880 (SD, $4194). An efficacy cost analysis of those completingrehabilitation showed the grand total costs were significantly lower for day3 compared with day 7 (Table 3).To further delineate these differences, Bonferroni-adjusted post hoc analyseswere conducted for major components of the grand total cost. These analysesindicated that hospital postoperative costs were significantly less for day3 patients and that hip replacements were more expensive than knee replacementsfor day-of-surgery costs. Other analyses stratified by type of surgery werenot significant. For rehabilitation costs (Table 3), physician costs were significantly higher for inpatientrehabilitation that was begun sooner for day 3 patients compared with day7 patients and the daily average for physical therapist plus occupationaltherapist costs indicated a higher daily fee for day 3 vs day 7 patients.This finding demonstrates that the day 3 group actually received more therapyper day than the day 7 group.

The daily FIM scores were analyzed to determine the rate of functionalchange during hospitalization. Because of the differing lengths of stay amongpatients, the distributional characteristics of patients' lengths of staywere evaluated and lower-, middle-, and upper-quartile values were computed.¹⁸ This statistical approach created 3 postoperativeperiods: days 1 through 5, days 6 through 10, and days 11 or higher. MeanFIM scores were computed for each of these periods for each patient.¹⁹ Data for days 11 or higher were not available forall patients because of the earlier discharge of some patients, as noted in Table 4 and Table 5.

As displayed in Table 4,significant differences in physical therapist–assessed FIM scores werefound between the day 3 vs day 7 groups, although no differences were notedwhen the data were stratified by surgery type. Specifically, transfers, ambulation,distance walked, and stair climbing scores were significantly higher (better)for the day 3 patients during days 6 to 10 of hospitalization. Additionally,day 3 patients compared with day 7 patients displayed significantly betterscores on ambulation and distance walked during days 1 to 5 of hospitalization.Results for the occupational therapist–assessed scores were similarto those of the physical therapist–assessed scores (Table 5), with the day 3 patients demonstrating significantly higherscores during days 6 to 10 of hospitalization for bathing and lower-extremitydressing.

Of the 86 patients randomized to the study, 71 patients (83%, 62 whocompleted rehabilitation and 9 dropouts) could be reached and returned thestandardized questionnaires at the time of the 4-month follow-up. SeparateMANOVA analyses for pretreatment FSI and RAND-36 scores between those completingthe follow-up questionnaires and those lost to follow-up indicated no significantdifferences.

Change scores for the FSI between the 4-month follow-up and pretreatmentvalues are presented in Table 6.A MANOVA analysis indicated no significant differences in the magnitude ofthese FSI changes between rehabilitation groups or between type of replacementsurgery. A separate MANOVA indicated patients displayed significant changesfrom pretreatment to the 4-month follow-up for the FSI pain and difficultyscales (P<.001), but not for the assistance scale.

Change scores for the 5 RAND-36 scales used in this study are displayedin Table 7.⁴All 3 physical domain scales displayed significant improvements from pretreatmentvalues at the time of the 4-month follow-up (both P<.001),but significant differences in the change scores were not found between rehabilitationgroups or replacement type. Similarly, change scores for the 2 mental domainscales were not significantly different between groups or replacements.

Within the follow-up interval, 2 patients had hip dislocation (1 day3 and 1 day 7), while another hip replacement patient (day 3) was ruled outfor deep vein thrombosis at a local emergency department. Three knee arthroplastypatients (all day 7) were readmitted to the hospital with diagnoses of deepvein thrombosis in 2 individuals and congestive heart failure was ruled outin another. The χ² analyses indicated no significant differencesbetween day 3 and day 7 groups with respect to follow-up complications (χ² [1df]=1.44, P=.30).

The results from this randomized trial indicate that high-risk individualsundergoing elective hip and knee arthroplasty had shorter total length ofstay, faster attainment of short-term functional milestones, and equivalentfunctional outcome at 4-month follow-up if they completed an inpatient rehabilitationprogram that began on the third rather than the seventh postoperative day.Patients in this cohort were primarily female, lived alone, had increasedcomorbidities, and were typical of elderly patients receiving total jointreplacement.²⁰ More important, the data showedthat this group could tolerate and benefit from early, intensive rehabilitation,which allowed a more rapid emphasis on physical independence and comprehensiveassessment of functional problems.¹¹ Patientsin the day 3 group did not have a higher rate of complications requiring transferfrom the rehabilitation unit or increased hospital readmissions once senthome. In addition, the day 3 group demonstrated longer ambulation distancewalked and superior FIM scores for mobility and self-care measures duringpostoperative days 6 to 11. The increased therapy attended per day by theday 3 group appears to be responsible for shorter total length of stay, sincefunctional milestones were attained sooner than for the day 7 patients.

Few studies have examined cost in relation to functional outcome afterhip and knee arthroplasty. Healy and Finn⁵and Barber and Healy⁶ examined the differencesin acute care costs pertaining to total-hip arthroplasty and total-knee arthroplastyduring a 10-year follow-up period and found significant price increases relatedmostly to the cost of the surgical implant. Liang et al¹³reported an average cost of $22730 per patient with significant improvementsin global health and functional status at 6 months postoperatively. Changet al²¹ found total-hip arthroplasty to becost-effective in improving quality-adjusted life years for both short- andlong-term outcomes. While these studies support the benefits of joint replacement,all patients were included rather than focusing solely on high-risk individualswho have higher hospitalization costs. In our earlier work, treatment algorithmsdiffered significantly depending on whether patients were at low or high riskfor requiring prolonged inpatient rehabilitation services after total-hiparthroplasty and total-knee arthroplasty.²

Similar to our results, Cameron and colleagues¹⁶randomized hip fracture survivors to receive either accelerated rehabilitationor standard care and found significant total cost reductions for the acceleratedgroup. In this study, decreased length of stay accounted for differences incost between groups even though the therapy cost per day was higher in theaccelerated treatment group.

Although 15 patients (17%) randomized to the study did not completethe rehabilitation arm because of dropouts or complications, there were nosignificant differences between day 3 vs day 7 exclusions for basic demographicand health status measures or in the composition of those excluded as comparedwith the remaining high-risk patients whose postoperative health status didnot interfere with rehabilitation transfer. An intention-to-treat analysisindicated that day 3 patients had a significantly shorter total length ofhospital stay compared with day 7 patients. However, an intention-to-treattotal cost analysis indicated no significant cost differences, even thoughan efficacy cost analysis of patients who completed rehabilitation demonstrateda mean cost savings of $1871 in favor of early rehabilitation. The reasonfor the different conclusions is that day 7–excluded patients had significantlylower total costs than day 3 exclusions, primarily because 4 of the 8 patientsin the day 7 exclusion group elected not to participate in the rehabilitationcomponent of the study even though this was deemed appropriate. Thus, if theearly inpatient rehabilitation program was generalized, it is likely thatoverall costs would, in the worst case, not increase and probably would decrease.

In conclusion, this study supports acute inpatient rehabilitation servicesbeginning on postoperative day 3 for high-risk patients unable to make transitionsto home after total joint replacement. These data also support the notionthat the rate of recovery can be hastened by settings that provide intensivetherapy services early after surgery.