Traumatic Onset of Medial Meniscus Posterior Root Tears Is Associated With Younger Age While Insidious Onset Is Associated With Chronic Overload and Bone Bruising.

PURPOSE: To evaluate clinical and radiographic findings for medial meniscus posterior root tears (MMPRTs) and investigate their associations with traumatic and insidious etiologies.

METHODS

Patients who underwent arthroscopic isolated MMPRT repair by one fellowship-trained surgeon from 2019 to 2023 were retrospectively identified. Clinical variables included history of present illness (HPI), medical history, and physical examination findings. Radiographic variables included Kellgren-Lawrence grade, bone bruise, ghost sign, truncation sign, linear hyperintensity perpendicular to the meniscus, meniscal extrusion, tibial slope, and mechanical axis. Patients were stratified by inciting event versus insidious onset for subgroup analysis.

RESULTS

Of 72 patients (mean age 56.7 ± 8.9 years, mean BMI 32.3 ± 5.7 k/m2), recollection of an inciting event was reported in 45.8% of patients. The most prevalent findings in the HPI were knee swelling (72.2%) followed by mechanical symptoms (62.5%) and episodes of perceived instability (45.8%), whereas medial joint line tenderness (93.1%) and a positive McMurray's test (69.4%) were commonly observed on physical examination. On MRI, ghost sign was identified in 91.7% of cases followed by truncation sign (83.3%) and a linear signal perpendicular to the meniscus (68.1%). The average measured meniscal extrusion was 4.18 ± 1.09 mm. Cases with an inciting event were more likely to be younger (P = .021), present acutely (P = .039), and have a positive McMurray test (P = .036). Cases with an insidious presentation were found to have higher rates of bone bruising at the medial femoral condyle (P = .016) and medial plateau (P = 0.029).

CONCLUSIONS

Patients with MMPRT associated with an inciting event are typically younger and more likely to present acutely, with a positive McMurray's test. Conversely, patients with insidious presentation are older, present chronically, and exhibit higher rates of bone bruising, particularly when there is varus malalignment.

LEVEL OF EVIDENCE: Level IV, prognostic case series.