Rehabilitation following first-time patellar dislocation: A randomised controlled trial of purported vastus medialis obliquus muscle versus general quadriceps strengthening exercises

Purpose: Define whether distal vastus medialis (VM) muscle strengthening improves functional outcomes compared to general quadriceps muscles strengthening following first-time patellar dislocation (FTPD).
Methods: Fifty patients post-FTPD were randomised to either a general quadriceps exercise or rehabilitation programme (n=25) or to a specific-VM exercise and rehabilitation regime (n=25). Primary outcome was the Lysholm Knee Score, secondary outcomes included the Tegner Level of Activity Scale, the Norwich Patellar Instability (NPI) Score, and isometric knee extensions strength at various knee flexion ranges of motion. Outcomes were assessed at baseline, six weeks, six months and 12 months.
Results: There were statistically significant differences in functional outcome and activity levels through the Lysholm Knee Score and Tegner Level of Activity Scale at 12 months in the general quadriceps exercise group compared to the VM group (p=0.05; 95% CI: -14.0 to 0.0/p=0.04; 95% CI: -3.0 to 0.0). This did not reach a clinically important difference. There was no statistically significant difference between the groups for the NPI Score and isometric strength at any follow-up interval. The trial experienced substantial participant attrition (52% at 12 months).
Conclusions: Whilst there was a statistical difference in Lysholm Knee Score and Tegner Level of Activity Score between general quadriceps and VM exercise groups at 12 months, this may not have necessarily been clinically important. This trial highlights that the recruitment and retention of participants from this population is a challenge and should be considered during the design of future trials in this population