Strength Training May Not Be Necessary Before TKA

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Preoperative knee extensor muscle strength training in patients with knee osteoarthritis may have no clinical effect on total knee arthroplasty (TKA), according to a systematic review published online this month in Osteoarthritis and Cartilage.

"This meta-regression analysis of existing trials suggests no relationship between the prescribed preoperative knee extensor exercise dosage and the change in knee extensor strength observed prior to and following TKA. Preoperative exercise including knee extensor muscle strength exercise increased knee extensor strength moderately prior to but not three months following TKA," wrote authors who were led by Rasmus Skov Husted, M.Sc., of Copenhagen University Hospital in Denmark.

Patients with knee osteoarthritis have low knee extensor muscle strength, more so in those with severe osteoarthritis awaiting TKA. Low knee extensor muscle strength is associated with decreased physical function independent of knee pain. Up to 80 percent of pre-operative knee extensor muscle strength is lost shortly after surgery. Prehabilitation of prescribed knee extensor muscle strength exercises may optimize physical function in patients awaiting TKA and may enhance post-surgical recovery. Information on changes in symptoms during prehabilitation may help decide whether surgical, or non-surgical treatment, is needed. Despite this potential for prehabilitation, there is little robust dose-response evidence. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

In this systematic review of 12 studies, which included 616 patients, the researchers evaluated the relationship between prescribed knee extensor strength exercise dosage and the effect on knee extensor muscle strength prior to and following total knee arthroplasty.

No relationship was found between prescribed preoperative knee extensor exercise dosage and change in knee extensor strength pre operatively or three months following total knee arthroplasty. Prior to total knee arthroplasty, a moderate effect favoring preoperative exercise for increase in knee extensor strength was found (standardized mean difference [SMD] 0.50 [95%CI 0.12 to 0.88]), but not at three post operatively (SMD -0.01 [95%CI -0.45 to 0.43]).

The authors suggested that the lack of a positive dose-response relationship may be because they analyzed the prescribed exercise dosage and not exercise adherence, and also that patients eligible for total knee arthroplasty may be able to achieve an increase in their knee extensor muscle strength by exercising at lower intensities.

Although not statistically significant, knee pain and physical function changed in a positive direction favoring the intervention, with a positive trend for improved physical function three months following total knee arthroplasty.

“We suggest changing the focus from prehabilitation―including preoperative exercise to enhance post operative recovery―to pre-evaluation which includes preoperative exercise to enhance shared surgical decision-making – in an enhanced recovery program after TKA,” the authors wrote.

"We suggest changing the focus from prehabilitation―including preoperative exercise to enhance postoperative recovery―to pre-evaluation, which includes pre-operative exercise to enhance shared surgical decision making in an enhanced recovery program after TKA. A patient eligible for TKA who has had no improvement in knee related symptoms following pre-operative exercise could be scheduled for surgery, while a patient with satisfactory improvements could continue non-surgical treatment," the authors wrote.

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REFERENCE

Rasmus Skov Husted, Carsten Juhl, Anders Troelsen, et al. “The relationship between prescribed pre-operative knee-extensor exercise dosage and effect on knee-extensor strength prior to and following total knee arthroplasty: A systematic review and meta-regression analysis of randomized controlled trials.”Osteoarthritis and Cartilage.September 2, 2020. DOI: https://doi.org/10.1016/j.joca.2020.08.011