Abstract
Aim
Pin site infection (PSI) is a common complication of external fixators. PSI usually presents as a superficial infection which is treated conservatively. This study investigated those rare cases of PSI requiring surgery due to persistent osteomyelitis (OM), after pin removal.
Method
In this retrospective cohort study we identified patients who required surgery for an OM after PSI (Checketts-Otterburn Classification Grade 6) between 2011 and 2021. We investigated patient demographics, aetiology of the OM, pathogen and histology, treatment strategies and complications. Infection was confirmed using the 2018 FRI Consensus Definition. Successful outcome was defined as an infection-free interval of at least 24 months following surgery, which was defined as minimum follow-up.
Results
Twenty-seven patients were treated due to a pin site infection with an osteomyelitis (22 tibias, 2 humeri, 2 calcanei, 1 radius). 85% identified as male and the median age was 53.9 years. Eighteen infections followed external fixation of fractures, with 4 cases after Ilizarov deformity correction, 2 cases followed ankle fusion and 3 after traction pin insertion. Fifteen patients were classified as BACH Uncomplicated and 12 were BACH Complex. The median follow-up was 3.99 years (2.00–8.05 years).
Staphylococci were the most common pathogens (16 MSSA, 2 MRSA, 2 CNS). Polymicrobial infections were present in 5 cases (19%).
All surgery was performed in a single stage following the same protocol at one institution. This included deep sampling, debridement, implantation of local antibiotics, culture-specific systemic antibiotics and soft tissue closure. Seven patients required flap coverage (6 local, 1 free flap), which was performed in the same operation.
25 (93%) patients had a successful outcome after one surgery. Two had recurrence of infection which was successfully treated by repeat of the protocol. One patient suffered a fracture through the operated site after a fall. This healed without infection recurrence. Wound leakage after local antibiotic treatment was seen in 3/27 (11%) of cases. All resolved without treatment.
After a minimum of 2 years follow up, all patients were infection free at the site of the former osteomyelitis.
Conclusions
OM after PSI is uncommon but has major implications for the patient as 7 out of 27 patients needed flap coverage. This reinforces the need for careful pin placement and pin site care to prevent deep infection. These infections require appropriate surgery, not just curettage. All patients in our cohort were infection-free after a minimum follow-up of 2 years suggesting that this protocol is effective.
