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. 2025 Jul;53(9):2118-2127.
doi: 10.1177/03635465251346952. Epub 2025 Jun 5.

Risk Factors for Subchondral Insufficiency Fracture of the Knee in the Setting of Medial Meniscus Posterior Root Tear

Jose Rafael Garcia  1   2 , Stephanie A Boden  3 , Zeeshan A Khan  1 , Myles A Atkins  1 , Felicitas Allende  1 , Michael J Murray  1 , Trevor A Poulson  1 , Michael Ralls  4 , Adam B Yanke  1 , Brian J Cole  1 , Nikhil N Verma  1 , Jorge Chahla  1
Affiliations

Risk Factors for Subchondral Insufficiency Fracture of the Knee in the Setting of Medial Meniscus Posterior Root Tear

Jose Rafael Garcia et al. Am J Sports Med. 2025 Jul.

Abstract

Background: Subchondral insufficiency fracture of the knee (SIFK) is commonly associated with medial meniscus posterior root tears (MMPRTs). However, there is limited research investigating risk factors for SIFK in patients with MMPRTs.

Purpose/hypothesis: The purpose of this investigation was to identify the risk factors for SIFK in patients with MMPRTs. It was hypothesized that age, body mass index, and extent of meniscal extrusion would emerge as significant risk factors for SIFK.

Study design: Case series; Level of evidence, 4.

Methods: Patients with a primary isolated MMPRT confirmed via magnetic resonance imaging were included. Data on patient demographics, medical and surgical history, and imaging parameters were assessed for associations with SIFK. Imaging parameters included mechanical axis, medial tibial slope, tibiofemoral joint space, and meniscal extrusion. Patients were identified and divided into 2 groups based on the presence or absence of findings of SIFK on magnetic resonance imaging. Continuous variable distribution normality was assessed using the Shapiro-Wilk test. Demographic comparisons were made by t tests and chi-square tests. Multivariable logistic regression was used to identify SIFK risk factors. The threshold of joint space for predicting SIFK was determined through receiver operating characteristic analysis. The optimal threshold was determined with the Youden index.

Results: A total of 153 patients were included (mean ± SD age, 56.2 ± 9.1 years): 90 patients (26 male, 64 female) in the non-SIFK group and 63 patients (16 male, 47 female) in the SIFK group. There were no differences in patient demographics between the cohorts. Patients with SIFK had a greater incidence of previous knee injections (P = .047), a significantly smaller tibiofemoral joint space (P < .001), and a significantly greater degree of meniscal extrusion (P = .041). Multivariable logistic regression analysis identified diminished joint space as the only independent predictor of SIFK (odds ratio, 0.41; P = .017). Receiver operating characteristic analysis determined a predictive threshold for joint space <3.93 mm, yielding an acceptable area under the curve of 0.766.

Conclusion: The development of SIFK is likely multifactorial; however, decreased tibiofemoral joint space is a significant independent risk factor for SIFK in patients with MMPRTs, with a greater risk in patients with a tibiofemoral joint space <3.93 mm.

Keywords: SIFK; SONK; joint space; meniscal tear; meniscus root; osteoarthritis; risk factors; spontaneous osteonecrosis; subchondral insufficiency.

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Conflict of interest statement

One or more of the authors has declared the following potential conflict of interest or source of funding: S.A.B. has received publishing royalties and financial support from Lippincott Williams & Wilkins. A.B.Y. has received consulting fees from AlloSource, JRF Ortho, and Stryker and research support from Arthrex and Organogenesis. A.B.Y. also holds stock or stock options in Icarus Medical, PatientIQ, and Sparta Biomedical. B.J.C. has received research support from Aesculap/B. Braun and Arthrex, consulting fees from Arthrex, and intellectual property royalties from Arthrex and Elsevier Publishing. B.J.C. also holds stock or stock options in Bandgrip Inc and Ossio. N.N.V. has received research support from Breg and Ossur; hospitality payments from Spinal Simplicity; consulting fees from Arthrex and Stryker Corporation; and royalties or licensing from Arthrex, Smith & Nephew, and Graymont Professional Products. J.C. has received consulting fees from Ossur, Arthrex, Smith & Nephew, DePuy Synthes Products, Linvatec Corporation, Vericel, and RTI Surgical Inc; research support from Arthrex; speaking fees from Arthrex, CONMED Corporation, Smith & Nephew, and Linvatec; and hospitality payments from Stryker and Medwest Associates. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

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