Background: Meniscal tears are traditionally classified into traumatic versus degenerative tears. Although this classification plays a major role in clinical decision making, no consensus exists on the exact definition of a traumatic or degenerative tear, and the histopathological basis for this classification is unclear.
Purpose: To assess the histological degree of meniscal degeneration in patients with a traumatic meniscal tear, as compared with intact meniscal tissue and osteoarthritic meniscal tissue.
Study design: Descriptive laboratory study.
Methods: Traumatically torn meniscal tissue was collected during arthroscopic partial meniscectomy. As a control group, intact meniscal tissue was used from transfemoral amputations or direct postmortem dissections. Meniscal tissue from osteoarthritic knees was obtained during total knee replacement surgery. Meniscal tissue was processed, stained, and histologically analyzed with the Pauli scoring system (range, 0-18), comprising the subdomains surface integrity, cellularity, collagen organization, and matrix staining. Scoring was performed by 2 independent observers, blinded to condition, region, and patient data of the meniscus.
Results: The traumatic meniscal tear group contained 43 patients (34 men; median age, 29 years; median body mass index [BMI], 24 kg/m2); the intact meniscal tissue group, 8 patients (3 men; median age, 58 years; median BMI, 30 kg/m2); and the osteoarthritic group, 14 patients (4 men; median age, 66 years; median BMI, 28 kg/m2). After adjustment for sex, age, and BMI, patients with a traumatic meniscal tear had a significantly higher histological score than patients with intact meniscal tissue (2.7-point difference; P = .035). Histological score between the traumatic and osteoarthritic groups was not different.
Conclusion: Traumatically torn menisci possess a higher degree of degeneration than intact menisci. Our results suggest that patients with a traumatic meniscal tear may already have had a certain degree of meniscal degeneration. These findings potentially challenge the classic view of traumatic versus degenerative meniscal tears.
Clinical relevance: Our findings provide a better understanding of the tissue condition of a torn meniscus. This knowledge may help clinicians decide on choice of treatment and may lead to new perspectives to prevent knee osteoarthritis in patients with a torn meniscus.
Keywords: arthroscopy; degeneration; meniscal tear; meniscectomy; meniscus.