Intraosseous tophaceous gout causing a pathological patellar fracture: A case report

Intraosseous tophaceous gout causing a pathological patellar fracture: A case reportTo the Editor, Tophaceous gout involving the patella is uncommon, and pathological fracture of the patella caused by intraosseous urate deposition is exceedingly rare.1,2 Diagnosis is particularly challenging when there is no previous history of gout and the patient presents after an acute traumatic event, because the fracture may be interpreted as purely traumatic and the underlying pathological bone destruction overlooked.We report a rare case of comminuted pathological fracture of the patella secondary to extensive intraosseous tophaceous gout in a patient without a known history of gout.A 53-year-old man was admitted with right knee pain and restricted motion 2 h after a ground-level fall while walking.Physical examination showed swelling, tenderness, and limited motion of the right knee.He denied any previous history of gout; therefore, serum uric acid was not measured preoperatively.Plain radiographs demonstrated a comminuted fracture of the right patella, and computed tomography (CT) showed multiple fracture fragments.No pathological lesion was recognized before surgery, and operative fixation was planned for a traumatic comminuted patellar fracture.Intraoperatively, however, extensive chalky tophaceous deposits were unexpectedly identified over the lateral surface of the patella and throughout the cancellous bone.The lateral part of the patella showed severe osseous destruction with partial cortical involvement.After curettage of the tophaceous material, a large intraosseous cavity remained, with only a thin shell of cortical bone preserved laterally.The fracture was reduced and stabilized using Kirschner wires and a tension-band construct.Postoperative serum uric acid was 653 μmol/L, supporting the diagnosis of gout.Operative findings were consistent with extensive intraosseous tophaceous deposition.Retrospective review of the preoperative CT images revealed an obvious osteolytic defect involving the lateral patella and a pre-existing cavity within the cancellous bone, indicating that substantial pathological bone destruction had occurred before the fall (Fig. 1).Patellar gout may produce erosive, osteolytic, or mass-like osseous lesions and can mimic primary bone tumors or other destructive conditions.1,3 Moreover, chronic urate deposition may progressively weaken local bone architecture and predispose to pathological fracture.2,4 The principal diagnostic difficulty in this case was the absence of a known history of gout.The acute