Purpose: Individuals after arthroscopic partial meniscectomy (APM) are at increased risk of developing knee osteoarthritis (OA). Knee muscle weakness and a higher external knee adduction moment (KAM) are potential risk factors for knee OA. This exploratory longitudinal study assessed these risk factors at baseline in an APM group (3 months after surgery) and control group, and again 2 yrs later (follow-up).
Methods: Eighty-two participants with medial APM and 38 healthy controls were assessed at baseline, with 66 (79%) and 23 (61%), respectively, retested at follow-up. Outcome measures included isokinetic knee muscle strength and medial knee joint load inferred through indices of the KAM during normal and fast-pace walking.
Results: Knee muscle strength was reduced by 14%–16% in the APM leg compared with controls at baseline (P ≤ 0.006). However, strength increased in the APM leg over the 2 yrs such that there were no differences compared with controls at follow-up. KAM impulse was at least 20% higher for the APM group (both legs) when compared with controls at baseline and remained similarly higher 2 yrs later (P ≤ 0.022). At baseline peak, KAM was 18% higher in the APM leg as compared with controls only during fast-pace walking (P = 0.013). The peak KAM increased over the 2 yrs in the APM leg by 8%–9% (P ≤ 0.032), although there were no differences in change in KAM between the APM leg and controls.
Conclusion: This study found that although knee muscle strength improved, dynamic medial joint load increased over the 2 yrs after APM surgery. These findings may aid in developing therapeutic interventions aimed to prevent or delay the onset of knee OA after APM.