Knee malalignment and laterality influence 2-year meniscus tear repair outcomes: A pilot study

To analyse biomechanical determinants for radiological and clinical outcomes of posterior horn longitudinal vertical meniscal tear (LVMT) repairs.

Patients undergoing primary repair of vascular zone traumatic full-thickness posterior horn LVMT were enroled. We hypothesized four potential factors would influence mid-term outcomes: malalignment (varus/valgus ≥5° for medial/lateral tears), meniscal laterality (medial vs. lateral), concomitant anterior cruciate ligament reconstruction (ACLR) and cartilage damage (Outerbridge grade ≥ II). The primary outcome was posterior horn nonhealing rate 6 months postoperatively (T1), evaluated using computed tomography arthrography (CTA) and Henning's criteria. Secondary outcomes were patient-reported outcomes measures (PROMs) assessed at T1 and ≥24 months postoperatively (T2). Univariate and multivariate logistic regression models estimated the marginal relative risk (MRR) of nonhealing for each determinant, while fractional logit regression assessed determinants' impact on PROMs at T1 and T2.

Seventy-eight patients (median age 29 years, interquartile range [IQR]: [21-37]); 76% male), were followed for ≥2 years (median 2.5 years, IQR: [2.1-3.6]). LVMTs extended to the middle horn in 81% and to the anterior horn in 52%. Posterior horn nonhealing rates (53%) were higher than in the middle (35%, p = 0.013) and anterior horn (7%, p < 0.001). Malalignment was present in 14%, medial meniscal involvement in 77%, ACLR in 55% and cartilage damage in 37%. Malalignment (MRR = 1.48, 95% confidence interval (CI): [0.84, 2.09]) and medial laterality (MRR = 1.7, 95% CI: [0.93, 3.6]) were independently identified as potential nonhealing risk factors. But it is the combination of varus malalignment and medial laterality that significantly increased the risk of nonhealing (MRR = 2.54, 95% CI: [1.09, 6.01], p = 0.033) and negatively impacted all Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales and International Knee Documentation Committee (IKDC) score at T1 and/or T2.

Combined varus malalignment and medial meniscus involvement strongly predicted repair nonhealing and poorer outcomes after posterior horn LVMT repair.

Prospective cohort pilot study.

Level III.