The Effects of Prehabilitation on the Outcome of Anterior Cruciate Ligament Reconstruction
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Introduction: Anterior cruciate ligament injury results in quadriceps femoris atrophy. The effects of atrophy can persist after 5 years post anterior cruciate ligament reconstruction (ACLR) and can prolong rehabilitation . Prehabilitation has been defined as preparing an individual to withstand a stressful event through enhancement of functional capacity before surgery . We hypothesise that a preoperative exercise programme would enhance postoperative recovery.
Aims: To determine the effects of a 6-week lower limb strengthening and proprioceptive training programme prior to ACLR on lower limb strength and function, muscle cross-sectional area (CSA) and self-reported assessment at baseline, preoperative and 12-week postoperative period. To identify alterations in gene and protein expression involved in muscle hypertrophy and atrophy pathways at the same time points.
Methods: 22 volunteers awaiting ACLR were randomly assigned to a control or exercise intervention group. The exercise group completed a supervised 6-week gym and home based exercise programme. Postoperatively, all patients had a standard physiotherapy programme for 12 weeks. Assessments were completed at baseline, preoperatively and 12-week postoperatively..Assessments for primary outcomes include the single leg hop test and isokinetic dynamometry (N = ll for each group). Other assessments such as MRI quadriceps and hamstring CSA, in-line lunge test, Modified Cincinnati Knee Rating System and Tegner-Lysholm Knee Score were also measured (N = ll and 9 in exercise and control group respectively). A percutaneous muscle biopsy of the vastus lateralis muscle was performed at the same time points under either local or general anaesthetic (during ACLR). IGF-1, MuRF-1 and MAFbx mRNA expression was determined with qRT-PCR. Myosin Heavy Chain (MHC) isoform expression was determined with SDS-PAGE and qRT-PCR.
Results: Following 6 weeks of exercise intervention, the single leg hop test improved significantly in the exercise-injured limb compared to baseline and controls (p=0.001, p=0.046 respectively). Quadriceps strength in the injured limb had improved with similar gains in CSA compared to baseline (p=0.001). The vastus medialis CSA was also increased compared to controls (p=0.015). The Modified Cincinnati Knee Rating System was also better compared to baseline.
At 12-week postoperatively, the decline in the single hop test was reduced in the exercise group compared to controls (p=0.001). Similar trends were seen for the quadriceps strength and CSA but were not statistically significant. The vastus medialis CSA had regressed to similar levels as the control group (p=0.008). The Modified Cincinnati Knee Rating System score continued to increase in the exercise group compared to controls (p=0.004).
The expression of IGF-1 gene was significantly increased after the exercise intervention (p=0.028), decreasing back to baseline 12-week postoperatively (p=0.012). MuRF-1 gene expression was decreased after intervention compared to baseline (p=0.05) but increased at 12-week postoperatively (p=0.Q3). MAFbx levels did not change significantly in either group and within each time point. On mRNA level, there was a shift from MHC-llx isoform to MHC-lla after exercise, with significant changes compared to controls preoperatively (p=0.03). Protein testing was only able to reproduce this increment for MHC-llx isoform expression only.
Conclusion: 6-week progressive prehabilitation programme for subjects undergoing ACLR is safe and led to improved knee function, quadriceps strength and CSA, and self-reported assessment pre- and postoperatively. This study supports prehabilitation as an important consideration for patients awaiting ACLR.