Extraosseous cement granuloma associated with total hip replacement in 6 dogs

Abstract

Objective: To report the clinical, radiographic, and pathologic features of extraosseous cement granuloma (ECG), a low occurrence, long-term complication of total hip replacement (THR).

Study design: Retrospective clinical study. Sample Population-Six client-owned dogs.

Methods: Medical records for 6 dogs that had a cemented modular THR and developed ECG were reviewed for the clinical, radiologic, and histopathologic findings of ECG. Morphologic and elemental analyses of retrieved particles were conducted in 2 dogs using scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS).

Results: Three golden retrievers and 3 Labrador retrievers had progressive lameness in the operated limb 4 to 7 years after THR and developed ECG. Other clinical features included an acute deterioration to non-weight bearing associated with pathologic fracture of the proximal femur in 2 dogs, and obstipation in 1 dog. In 5 dogs, there was a large caseous mass surrounding the proximal femur. Obstipation in 1 dog was caused by a similar mass adjacent to bone cement used for fixation of the acetabular cup. Radiographic changes included a multilobular soft tissue mass, containing irregular mineral densities, in the gluteal mass surrounding the proximal femur, THR interface deterioration, osteolysis, new bone formation, and implant subsidence were consistent with chronic aseptic loosening. The histopathologic diagnosis was sterile granuloma associated with a massive heterogeneous particulate burden, which was assumed to have resulted from severe wear of all prosthesis components.

Conclusions: ECG is a manifestation of severe aseptic loosening of cemented total hip replacement, with the generation of wear debris probably responsible for granuloma formation.

Clinical relevance: Because revision can offer a good prognosis in early aseptic femoral loosening, yearly radiographic monitoring of the recipients is recommended.