Prosthetic joint infection following hip fracture and degenerative hip disorder: a cohort study of three thousand, eight hundred and seven consecutive hip arthroplasties with a minimum follow-up of five years.

Purpose: Prosthetic joint infections (PJIs) occur on a regular basis and with an increasing incidence. Under reporting of complications to national registries and unreliable ICD-10 coding increases the risk of under estimating the true rate of PJIs after hip arthroplasty. Also, the microbiology and final outcome is less well described, especially for hip-fracture patients operated upon with primary and secondary fracture prostheses. Our aim was to analyse re-operation rate, outcome and microbiology of PJIs following hip arthroplasty in patients operated upon due to hip fractures and degenerative hip disorders.

Methods: This was a single-centre cohort study of 3807 consecutive hip arthroplasties performed between 1996 and 2005. The primary study outcome was to compare the incidence of PJIs. The secondary outcome was to analyse the microbiology and outcome of PJIs.

Results: We identified 62 PJIs: seven surgical-site PJIs were found in patients operated upon for a degenerative hip disorder, 22 [hazard ratio (HR) 4.3] were found in patients operated upon for a primary fracture and prosthesis and 25 (HR 6.1) in patients operated upon with a secondary fracture and prosthesis. Outcome treatment was unfavourable for hip fracture patients with a high rate of Girdlestone operation performed (22 of 27). Staphylococcal infections dominated in the fracture group, whereas polybacterial infections were more common in patients with degenerative hip disorder.

Conclusions: Patients with a displaced femoral neck fracture treated primary or secondary with arthroplasties have a greater risk of PJIs and display worse outcomes compared with patients with a total hip replacement due to degenerative hip disorders.