Background/Purpose: Previous epidemiologic studies have established that there is a strong relationship between meniscal tear and the risk for subsequent development of osteoarthritis (OA). Though not normally considered a classical inflammatory arthropathy, OA is often associated with low-grade synovitis. In patients with OA, synovial inflammation is one factor associated with risk of progression of structural joint deterioration and symptoms. The aims of the study were to characterize the synovial features in patients undergoing partial meniscectomy for meniscal tear.

Methods: The study was conducted in the context of a three-year project funded by the Italian Ministry of Health (Ricerca Finalizzata – Giovani Ricercatori – project code: GR-2010-2317593),  which maintains extensive records of preclinical, intraoperative and post-operative data so far for 58 patients who have undergone meniscectomy for both degenerative and traumatic meniscal tear. Synovial biopsies were collected in suprapatellar area during arthroscopic surgery and processed for histology. Synovial features of inflammation were assessed using an histological synovial scoring based on perivascular mononuclear cell infiltration as follows: grade 0=none, grade 1=mild (0-1 perivascular aggregates per low-power field); grade 2=moderate (>1 perivascular aggregate per low power field with or without focal interstitial infiltration); grade 3=marked aggregates (both perivascular and interstitial) (Scanzello CR, Arthritis Rheum. 2011). The following clinical data were collected: age, sex, BMI, date of injury and time to surgery, pre-operative VAS and KOOS, 3-6 months KOOS and meniscal tear characteristics and/or cartilage pathology. Cartilage damage was assessed intra-operatively using the Outerbridge scoring system. 

Results: In the series of 58 patients, males were predominant (72%) with median ages of 43.6 and 50 years, respectively. Meniscal tear were traumatic in 50% of patients. KOOS at 3-6 months after meniscectomy statistically improved compared with the baseline (p<0.0001). No association was observed between traumatic or degenerative meniscal tear and age, BMI, KOOS, frequency of cartilage defects or macroscopic synovitis score. Of 26 suprapatellar synovial biopsies H&E stained: 15 exhibited mild synovial inflammation, 7 moderate, 1 marked. Cartilage defects were observed in 48 patients (82,7%). 35 patients had multiple cartilage defects, while 13 exhibited only a single focal chondral lesion. Outerbridge scores were distributed as follows: grade I (7 patients), grade II (13 patients), grade III (16 patients) and grade IV (12 patients). The grade of cartilage defects correlated with synovial inflammation assessed by histological scoring (r =0,500; p = 0,009) and both patients age and BMI. 

Conclusion: In our study, we observed an high percentage of low-grade synovitis (88%), and/or cartilage defects (82,7%) in patients undergoing partial meniscectomy for meniscal tear. Microscopic synovial inflammation correlate with the grade of cartilage defect confirming that synovitis play a role in the progression of the disease.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/synovitis-characteristics-and-associated-intra-articular-pathology-in-a-cohort-of-patients-undergoing-meniscectomy-for-meniscal-tear/