The arcOGEN study identified the 9q33.1 locus as associated with hip osteoarthritis (OA) in females. TRIM32 lies within this locus and may have biological relevance to OA; it encodes a protein with E3 ubiquitin ligase activity.

Sanger sequencing of TRIM32 in the youngest 500 female patients with hip OA from the arcOGEN study identified genetic polymorphisms in the proximal promoter, and 3'untranslated region of TRIM32 that are disproportionately represented in female patients with hip OA compared to the control population.

Reduced expression of TRIM32 was identified in femoral head articular chondrocytes from patients with hip OA compared to control patients. Trim32 knockout resulted in increased aggrecanolysis in murine femoral head explants. Murine chondrocytes deficient in Trim32 exhibited increased expression of mature chondrocyte markers following anabolic cytokine stimulation, and increased expression of hypertrophic chondrocyte markers following catabolic cytokine stimulation.

Trim32 knockout mice demonstrated increased cartilage degradation and tibial subchondral bone changes after surgically-induced knee joint instability. Increased cartilage degradation and medial knee subchondral bone changes were also identified in aged Trim32 knockout mice.

These results further implicate TRIM32 in the genetic predisposition to OA, and indicate a role for TRIM32 in the joint degeneration evident in OA. These results support the further study of TRIM32 in the pathophysiology of OA and development of novel therapeutic strategies to manage OA.

Paget's disease of bone (PDB) is the second most common metabolic bone disease. Osteoarthritis (OA) affects one-third of patients with PDB. The incidence of THR (total hip replacement) and TKR (total knee replacement) is 3.1- and 1.7-fold higher in PDB patients compared to non-affected age-matched controls. No large studies or joint registry reports exist describing the outcomes following THR or TKR in patients with PDB.

The objectives of this study were to investigate the outcomes following THR and TKR in patients with PDB using national joint registry data. 144 THR and 43 TKR were identified using the Scottish Arthroplasty Project from 1996–2013.

For THR, the most common early post-operative surgical complications were haematoma formation (1.4%), and surgical site infection (1.4%). The absolute incidence during follow-up of dislocation was 2.8%, and revision hip arthroplasty was performed in 2.8% of cases. Implant survival of the primary prosthesis was 96.3% (CI: 92.8 – 99.8) at 10-years, and patient survival was 50.0% (39.6 – 60.4) at 10-years.

For TKR, the most common early post-operative surgical complication was surgical site infection (2.3%). The absolute incidence during follow-up of revision knee arthroplasty was 4.7%. On survival analysis, implant survival of the primary prosthesis was 94.5% (CI: 87.1 – 100) at 10-years, and patient survival was 38.3% (16.7 – 59.9) at 10-years.

This is the largest reported series of outcomes following primary THR and TKR in patients with PDB. PDB patients are not at increased risk of surgical complications following primary THR or TKR compared to non-PDB patients.