Post‐arthroscopic Subchondral Insufficiency Fractures of the Knee Yield High Rate of Conversion to Arthroplasty
Laurel A. Barras, Ayoosh Pareek, Chad W. Parkes, Bryant M. Song, Christopher L. Camp, Daniël B.F. Saris, Michael D. Stuart, Aaron J. Krych
Abstract
PURPOSE: To evaluate both the potential causes and resultant outcomes in patients in whom subchondral insufficiency fracture of the knee (SIFK) develops after arthroscopy. METHODS: We performed a retrospective review of all patients with a magnetic resonance imaging diagnosis of SIFK after arthroscopic meniscectomy and chondroplasty over a 12-year period. RESULTS: A total of 28 patients were included, with a mean age of 61 years and mean follow-up period of 5.7 years. SIFK showed a predilection for the medial compartment (n = 25, 89%), specifically the medial femoral condyle (n = 21, 75%). In 7 patients (25%), SIFK developed in both the femoral condyle and tibial plateau in the ipsilateral compartment. Fifteen patients (54%) went on to conversion to arthroplasty at a mean of 0.72 years. The rate of survival free of conversion to arthroplasty was 57%, 45%, and 40% at 1 year, 2 years, and 5 years, respectively. Furthermore, 63% of patients with a meniscal tear and SIFK in the same compartment went on to arthroplasty (P = .04). There was an increased risk of conversion to arthroplasty if SIFK was present in both the femur and tibia in the same compartment (P = .04). A higher Kellgren-Lawrence grade at the time of the SIFK diagnosis increased the likelihood of eventual arthroplasty (P = .03). The presence of SIFK in both the femur and tibia in the ipsilateral compartment, an increased Kellgren-Lawrence grade, and a meniscal tear or prior meniscectomy in the same compartment as SIFK were associated with an increased risk of eventual arthroplasty. CONCLUSIONS: Post-arthroscopic SIFK most commonly occurs in the medial compartment, particularly in patients who underwent a prior meniscectomy. The presence of meniscal root and radial tears in these patients is notable (75%). Ultimately, there is a high rate of progression of arthrosis (33%) and eventual conversion to arthroplasty. LEVEL OF EVIDENCE: Level IV, case series.