Objective: To determine the characteristics of femoral condyle insufficiency fracture (FCIF) lesions and their relative associations with the risk of clinical progression.
Materials and methods: This HIPAA-compliant retrospective study was approved by our Institutional Review Board. Seventy-three patients (age range, 19-95) were included after excluding patients with post-traumatic fractures, bone marrow infarct, osteochondritis dissecans, or underlying tumor. Two board-certified musculoskeletal radiologists classified morphologic findings including lesion diameter, associated bone marrow edema pattern, and associated cartilage/meniscus damage. Electronic medical charts were evaluated for symptoms, risk factors, and longitudinal outcomes, including total knee arthroplasty (TKA). Imaging characteristics were correlated with clinical findings, and comparison of outcome groups was performed using a regression model adjusted for age.
Results: The majority of patients with FCIF were women (64.4%, 47/73), on average 10 years older than men (66.28 ± 15.86 years vs. 56.54 ± 10.39 years, p = 0.005). The most common location for FCIF was the central weight-bearing surface of the medial femoral condyle; overlying full thickness cartilage loss (75.7%, 53/70) and ipsilateral meniscal injury (94.1%, 64/68) were frequently associated. Clinical outcomes were variable, with 23.9% (11/46) requiring TKA. Cartilage WORMS score, adjacent cartilage loss, and contralateral meniscal injury, in addition to decreased knee range of motion at presentation, were significantly associated with progression to TKA (p < 0.05).
Conclusions: FCIF are frequently associated with overlying cartilage loss and ipsilateral meniscal injury. The extent of cartilage loss and meniscal damage, in addition to loss of knee range of motion at the time of presentation, are significantly associated with clinical progression.
Keywords: Femoral condyle; Insufficiency fracture; Magnetic resonance imaging; Spontaneous osteonecrosis of the knee.