Progression of patellofemoral joint cartilage degeneration within 1 year after medial meniscus posterior root repair: A retrospective study

Purpose: To assess postoperative progression of patellofemoral (PF) cartilage degeneration after medial meniscus posterior root (MMPR) repair and identify potential risk factors.
Methods: Data from patients who underwent transtibial pullout repair for complete radial MMPR tears between April 2018 and October 2021 were retrospectively investigated. Patients with severe chondral lesions of the PF joint at primary surgery were excluded. All patients underwent second-look arthroscopy at 12 months postoperatively. Postoperative changes using the International Cartilage Repair Society (ICRS) grade were evaluated. Associated open magnetic resonance imaging (MRI) findings were assessed.
Results: In total, 40 patients (30 women, 10 men; mean age: 64.0 years) were evaluated. PF joint cartilage degeneration progressed significantly postoperatively. Abnormal signal intensity (ASI) of the infrapatellar fat pad (IPFP) was observed in 15 (37.5%) patients. Arthroscopic findings in groups between IPFP with and without ASI were compared. The incidence of postoperative ICRS grade worsening (≥2 grades) on the patella or trochlea was significantly higher among patients with ASI (53%) than among those without (20%, p = 0.04). ICRS grade worsening in the medial femorotibial compartment and meniscus-healing status were comparable between the groups. Patients with ASI of the IPFP showed greater decrease in the distance between the patellar and anterior cruciate ligament insertions on knee flexion MRI (−1.5 ± 0.7 mm) than that in those without (−0.2 ± 0.3 mm, p < 0.01). A delayed rehabilitation protocol was a risk factor according to the logistic regression analysis (p = 0.01).
Conclusions: Progressive PF cartilage degeneration occurred following MMPR repair, highlighting the need for diligent postoperative PF joint management.
Level of Evidence: Level IV case series.