Exercise Before Joint Replacement Improves Post-Op Function

BOSTON, Sept. 29 -- Exercise in the six weeks before a hip or knee replacement led to significant improvements in preoperative muscle strength and a 73% lower-risk of needing care at a rehab facility after arthroplasty, reported researchers here.

Patients who were randomized to the six-week preoperative regimen of water- and land-based exercise also had significant improvements in muscle strength compared with controls, found Daniel S. Rooks, Sc.D., of Beth Israel Deaconess Medical Center, New England Baptist Hospital, in Boston.

Men and women who exercised prior to getting new joints were also more likely to walk more than 50 feet in the early post-op period, the investigators noted in the October issue of Arthritis Care & Research.

But while both hip and knee replacement candidates improved their lower-extremity muscle strength preoperatively, there were pre-op improvements in function only in patients slated for a total hip.

"Exercise is a cornerstone of rehabilitation following total joint arthroplasty and other surgical procedures," the investigators wrote. "Little attention, however, has been placed on the potential role exercise might play in preparation for surgery."

The investigators randomized 108 patients scheduled for total-hip or total-knee arthroplasty to a six-week exercise program or to receive educational materials (controls).

The exercise protocol included water and land-based exercise for 30 to 60 minutes three times weekly over the six weeks immediately prior to surgery. The exercises were tailored to the fitness levels of the individual patients, and were performed in groups under at a community fitness center under supervision.

Pool exercises, performed during the first three weeks, focused on single planar motion of the cervical spine, shoulders, elbows, wrists, hands, hips, knees, and ankles. During weeks four through six, exercise sessions involved a total body fitness program of cardiovascular, strength, and flexibility training.

The investigators assessed outcomes with questionnaires and performance measures, including the Western Ontario and McMaster Universities Osteoarthritis Index for disease-specific assessment, and the Short Form 36 physical function index for assessment of general function.

Fifty-nine total-hip replacement candidates (25 in the exercise group and 24 in the control group) and 29 total-knee replacement candidates (14 exercisers and 15 controls) completed the study. The groups were evaluated during the preoperative and immediate post-op periods, and again at eight and 26 weeks following joint replacement surgery.

The authors found that for the patients scheduled for hip replacement, the exercise intervention was associated with a 2.2 point improvement in the preoperative Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index function score. In contrast, controls had 3.9 point decline (P= 0.02), with negative changes in both pain and function scales.

On the Short Form 36 physical function index, hip candidates, both exercisers and controls, experienced a decline, but the decrease in function was significantly more pronounced among controls compared with exercisers (-0.4 in exercisers versus -14.3 in controls; P =0.003).

There were no significant differences between groups of patients scheduled for total-knee replacement.

The investigators also found that exercise increased preoperative muscle by 18% in hip-replacement patients and by 20% in knee-replacement patients, while controls showed no significant changes in strength.

Exercise also was a good predictor of which patients could be discharged home after surgery rather than to a rehab facility. In all 65% of exercisers (hip and knee recipients combined) were discharged directly home after their inpatient stay, and 35% went to an inpatient rehab facility. In contrast, 44% of controls went home, and 56% went to rehab after surgery.

Two-thirds (76%) of pre-op exercisers were also able to walk at least 50 feet on the third hospital day, compared with 61% of controls.

In stepwise logistic regression models, the odds ratio for discharge to rehabilitation for exercisers vs. controls was 0.27 (95% confidence interval, 0.074-0.998).

The adjusted odds ratio for exercisers being able to walk more than 50 feet on day 3 was 3.2 (95% CI, 1.2-8.9).

Preoperative exercise did not, however, have any effects on outcomes at either eight- or 26-week follow-up, the authors noted.

"Our findings show that an appropriately designed program of water and land-based exercise involving cardiovascular, strength training, and flexibility activities can be a safe, well tolerated, and effective approach to improving function and muscle strength in middle-aged and older adults with severe osteoarthritis of the hip and knee," they wrote.

The investigators suggested that the strength-training component of the exercise protocol, which was shorter than that normally required for significant strength gains, may have worked through a combination of increased neuromuscular coordination and "a reduction in fear of anticipated pain associated with increased muscular effort."

"Our most striking finding," the authors wrote, "was that regardless of affected joint, participating in the exercise intervention reduced the odds of discharge to a rehabilitation facility by 73%. A greater proportion of nonexercisers (54%) went to inpatient rehabilitation facilities compared with exercisers (33%)."

The findings conflict with those of a 1998 study showing the patients scheduled for total knee arthroplasty who exercised preoperatively were more likely to need inpatient rehabilitation on hospital discharge.

Nevertheless, "the potential economic implication of this finding is noteworthy and should be examined in future studies, particularly with the rise in inpatient rehabilitation use," they added.

The authors acknowledged study limitations that included a low recruitment rate (only 12% of eligible patients), and dropouts (some due to the inconvenience of traveling to the fitness center), which could have reduced the evidence for the efficacy of exercise by eliminating those patients who could have benefited most from the intervention.