Giant Intra-Articular Extrasynovial Osteochondroma of the Knee: A Report of Two Cases

Abstract

We report two cases of a giant extrasynovial osteochondroma of the knee located in the infrapatellar fat pad region, in two females who were 58 and 71 years old respectively. Both patients had noticed the mass many years before our first clinical observation. In both patients, at physical examination a solid, firm and hard mass was palpable in the anterior part of the knee in Hoffa’s fat pad region, and the range of motion of the knee was severely restricted and painful. CT scan examination with 3D-reconstruction showed two large, calcified neoformations behind the patellar tendon, between the apex of the patella and the proximal third of the tibia. In both cases, the mass was completely resected surgically through an anterior longitudinal approach. At histological examination, the excised masses consisted of an outer layer of hyaline cartilage without significant chondrocyte atypia and an inner region of bone trabeculae formed by endochondral ossification. At follow-up, 8 and 4 years after the operation, both patients were pain-free, with complete recovery of the range of motion of the knee and without any clinical or radiographic evidence of recurrence. The authors believe that intra-articular extrasynovial osteochondroma of the knee is a primary metaplasia of Hoffa’s fat pad. Usually, the tumor develops slowly and asymptomatically over many years. The treatment of choice is a marginal resection of the mass, although a biopsy should be considered in some cases. Recurrences are extremely rare.

Giant intra-articular extrasynovial osteochondroma of the Hoffa's fat pad

“…2 The term 'giant intra-articular extrasynovial osteochondroma' was first used by Maio et al 9 There may be dense fibrous attachment of these lesions to the tissues around the tibial plateau or the coronary ligament of the meniscus. 8 On lateral radiographs and computerized tomography (CT), foci of calcification to rounded ossifying masses are seen in the Hoffa's fat pad.…”

“…Apart from primary metaplasia, the proposed triggers for metaplasia include trauma and chronic impingement of the infrapatellar fat pad. 9 Grossly, these tumours are characterized by a solitary mass composed of multiple osteochondral nodules. Histologically, these entities consist of peripheral cartilaginous areas with central lamellar, trabecular bone.…”

A Different Reason of Painful Popliteal Region: Atypically Localized Tibial Osteochondroma (Case Report)

“…İskelet dışı osteokondromlar ise oldukça nadirdir. Popliteal bölgede veya diz çevresinde görülen eklem içi vakalar literatürde yayınlanmıştır (3)(4)(5)(6)(7)(8). Bu yayınların bazılarında osteokondromun popliteal arter ve veni baskıya uğratarak dolaşımı bozduğu gösterilmiştir (3)(4)(5).…”

An unusual management of advanced gonarthrosis: total knee arthroplasty with posterior approach

“…Neden oldukları en temel sorun eklem hareket genişliğindeki kısıtlanmadır. [16,17] Şikayete neden olmayan osteokondromların tedavisi genellikle yalnızca izlemdir. Şikâyete ya da komplikasyona neden olduğu durumlarda cerrahi olarak tedavi edilir.…”