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%, 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.