Correlation of tibial and femoral morphological characteristics with medial meniscus posterior root tears and postoperative outcomes

Medial meniscus posterior root tears (MMPRTs) are clinically important lesions that impair hoop stress distribution and may cause progressive degeneration if untreated. Although several demographic and biomechanical factors have been reported, the independent role of tibial and femoral morphology remains unclear. The purpose of this study was to evaluate these morphological characteristics and their association with postoperative clinical outcomes after arthroscopic repair. This retrospective cohort included 64 patients with isolated degenerative MMPRT and a preserved mechanical axis who underwent arthroscopic transtibial pullout repair, and 64 control subjects without meniscal, ligament, or alignment pathology, selected to match the MMPRT group for age, sex, and BMI. Radiographs and MRI were analyzed for medial tibial slope (MTS), medial tibial plateau depth (MTPD), medial femoral condyle angle (MFCA), medial femoral condyle width (MFCW), medial tibial plateau width (MTPW), MFCW/MTPW ratio, intercondylar notch width (ICNW), intercondylar distance (ICD), ICNW/ICD ratio, and distal/posterior condylar offset ratios. Clinical outcomes (International Knee Documentation Committee [IKDC], Lysholm, Tegner) were assessed preoperatively and at two years. Osteoarthritis progression was evaluated using Kellgren–Lawrence (K–L) grade and medial joint space width (JSW). The MMPRT group demonstrated steeper MTS, shallower MTPD, higher MFCA, narrower ICNW, smaller ICD, lower ICNW/ICD ratio, and reduced distal and distal/posterior offsets compared with controls (all p < 0.001). MFCW, MTPW, and the MFCW/MTPW ratio did not differ significantly. At 2 years, IKDC, Lysholm, and Tegner improved significantly (all p < 0.001), while K-L grade and JSW remained unchanged. Improvements in IKDC and Lysholm were negatively associated with MFCW, MTPW, and the MFCW/MTPW ratio. Steeper MTS, shallower MTPD, higher MFCA, narrower ICNW, smaller ICD, lower ICNW/ICD ratio, and decreased distal and distal/posterior offsets were found to be significantly associated with MMPRT. Associations between MFCW, MTPW, and postoperative outcomes suggest that femorotibial geometric congruence may have prognostic value following root repair.