Tear location of posterior cruciate ligament tears: introduction and reliability of a magnetic resonance imaging-based classification.

Objective: To introduce a tear location classification system for posterior cruciate ligament (PCL) injuries, aiming to unify diagnostic criteria and improve clinical decision-making based on tear location.

Materials and methods: A retrospective analysis was conducted using magnetic resonance imaging (MRI) examinations from a single institution, identifying all patients with acute or subacute PCL injuries from 2008 to 2024. Ligament sprains without significant fiber disruption and chronic injuries were excluded. Tears were classified by four independent observers according to the relative length (%) of the intact distal remnant compared to the total PCL length: Type I (> 90%), Type Ib (femoral bony avulsion), Type II (90-75%), Type III (75-25%), Type IV (distal tear 10-25%), Type V (< 10%), and Type Vb (tibial bony avulsion). For intra-observer reliability analysis, measurements were repeated once by two observers after 4 weeks.

Results: A subset of 45 MRIs with diagnosed PCL injuries that met the inclusion criteria (mean age 40.5 ± 19.2 years, 40% female) had 24% proximal tears, 33% midsubstance tears, 33% distal tears, and 11% single-bundle injuries. Inter-observer reliability (Fleiss' kappa, 0.88; 95% CI, 0.84-0.94; p < 0.01) and intra-observer reliability demonstrated to be almost perfect (Cohen's kappa, 0.95; 95% CI, 0.86-0.99 & 0.92; 95% CI, 0.84-0.99).

Conclusion: The proposed MRI-based classification system-which includes femoral avulsion, proximal quarter, midsubstance (50%), distal quarter, and tibial avulsion injuries-offers a reliable method for identifying the anatomical location of partial and complete PCL injuries. Standardizing tear localization has the potential to improve diagnostic consistency and inform more tailored, evidence-based treatment strategies.

Level of evidence: Diagnostic study; III.