Monoarticular synovitis of knee: dealing with the dilemma

Abstract

Introduction: Chronic synovitis involving a single large joint remains a diagnostic dilemma. We present 61 cases of chronic synovitis of the knee, followed prospectively for 2 years. The study focuses on the diagnosis, management, and histopathological correlation.

Methods: We prospectively studied 61 patients with chronic mono-articular synovitis of the knee joint, between July 2016 and September 2017. All patients underwent plain radiographs, magnetic resonance imaging, and arthroscopic examination with synovial biopsy. Further treatment was based on findings of histopathological examination.

Results: The average duration of symptoms was 7.72 ± 4.34 months. The mean age at presentation was 29.93 ± 15.56 years. Results of histopathological examination showed chronic nonspecific inflammation in 28 patients (46%), features suggesting tubercular infection in 19 patients (31%), pigmented villonodular synovitis in seven patients (11.5%), rheumatoid arthritis in three (5%) patients, acute inflammation in three (5%) patients and findings suggestive of synovial chondromatosis in one (1.5%) patient. Treatment was based on histopathological results. Intra-articular injections of methylprednisolone (80 mg depot preparation) were given to all patients with nonspecific synovitis and rheumatoid arthritis. Anti-tubercular treatment was started for patients with tubercular synovitis. Complete arthroscopic/open synovectomy followed by radiotherapy was carried out for patients with pigmented villonodular synovitis. Non-steroidal anti-inflammatory drugs are used for patients with acute on chronic inflammation. All patients had symptomatic relief and functional improvement in further follow-up.

Discussion: Histopathological reporting remains the mainstay for diagnosis. The various differentials should always be kept in mind when approaching patients with chronic mono-articular synovitis. Specific treatment can be started once the diagnosis is confirmed.

Keywords: Chronic synovitis; Knee; Level IV; Monoarticular synovitis; Observational study; Synovectomy; Synovial biopsy.

Figure 1

Intraoperative arthroscopic image showing punch biopsy being taken in a case of pigmented vilo-nodular synovitis.

Figure 2

Figure depicting the 40× microscopic views of various etiologies of monoarticular synovitis of the knee (A – chronic synovitis, B – tubercular granulomatous inflammation, C – rheumatoid arthritis and D – pigmented villo-nodular synovitis of knee).

Figure 3

Figure showing MRI sections of a patient with inflammatory synovitis (A – axial PDFS, B – sagittal T2, C – coronal PDFS, sagittal PDFS showing hyperintensity in subarticular marrow of the tibia and femur with post-contrast enhancement and moderate effusion with diffuse enhancing synovial thickening).

Figure 4

Figure showing MRI sections of a patient with infective pathology (A – coronal STIR, B – sagittal STIR, C – coronal T1, D – sagittal STIR images showing moderate effusion with peripherally enhanced intensities in popliteal fossa).

Figure 5

Figure showing MRI sections of a patient with pigmented villo-nodular synovitis of knee (A – sagittal STIR, B – axial STIR, C – sagittal T1, D – coronal STIR images showing nodular synovial thickening with foci of blooming within patellar tendon, Hoffa’s pad of fat, quadriceps tendon, and popliteal fossa).

Figure 6

Flowchart showing treatment plan in chronic monoarticular synovitis.