PRE-OPERATIVE EXERCISE ENHANCES STRENGTH, FUNCTION AND MUSCLE STRUCTURE POST TKA: A RANDOMIZED CONTROLLED TRIAL

Abstract

Introduction: Quadriceps femoris (QF) atrophy has been associated with the development of knee OA and is a major cause of functional limitations in affected individuals. TKA reliably reduces pain but improvements in function are less predictable and deficits may persist for up to 2 years post-operatively. Patients undergoing elective surgery are routinely optimized medically but we hypothesized that pre-operative strength and fitness improvements would also enhance outcome.

Objectives: To determine the effect of a 6 week lower limb strengthening programme on post-operative QF strength and CSA, pain and functional scores.

To determine changes in Myosin Heavy Chain (MHC) isoform, hypertrophy marker IGF-1 and atrophy markers MuRF-1 and MAFbx.

Methods: 20 volunteers currently awaiting TKA were randomly assigned to a control [C] or intervention [I] group. [I] completed a 6 week home based, supervised exercise programme. Post-operatively all patients completed a standard inpatient physiotherapy routine.

Assessments were completed at baseline (T=0), T=6 weeks (just prior to operation) and 3 months post-operatively (T=18 weeks). Assessments included isokinetic dynamometry; MRI QF CSA and American Knee Society scores. A percutaneous muscle biopsy of the vastus lateralis muscle was also performed at T=0 and T=6 under local anaesthesia.

Results: At baseline there were no significant differences in parameters between groups. At T=18, [I] showed an 86% difference in QF peak torque above controls (P=0.003). CSA also improved by 6% versus a drop of 2.5% in [C] (P=0.041). Both groups showed improvements in Knee society function scores but [I] improved by 13 points more than [C] (P=0.044).

MHC IIa mRNA expression increased by 40% whilst IIx decreased by 60% representing a shift to a less fatigable fibre type (P=0.05 and 0.028 respectively). IGF-1, MuRF-1 and MAFbx mRNA levels did not change significantly in either group.

Conclusion: To our knowledge we have documented for the first time post-operative benefits by using a pre-operative training programme in TKA. This was manifest by continued rise in quadriceps peak torque, CSA and improved Knee society functional scores. We have also demonstrated the preservation of muscle plasticity in knee OA and suggest that factors other than known hypertrophy and atrophy pathways may be responsible.