Should nails be locked dynamically or statically in atypical femoral fractures? - A radiological analysis of time to union and reoperations in 236 displaced fractures with 4 years average follow-up.

INTRODUCTION: Atypical femoral fractures (AFFs) are associated with delayed union and higher reoperation rates. Axial dynamization of intramedullary nails is hypothesized to reduce time-to-union (TTU) and fixation failure as compared to static locking. METHODS: Consecutive acutely displaced AFFs fixed with long intramedullary nails across five centres between 2006 and 2021 with a minimum postoperative follow-up of three months were retrospectively reviewed. The primary outcome was TTU, compared between AFFs treated with dynamically or statically locked intramedullary nails. Fracture union was defined as a modified Radiographic Union Score for Tibial fractures score of 13 or greater. Secondary outcomes involved revision surgery and treatment failure, defined as non-union beyond 18 months or revision internal fixation for mechanical reasons. RESULTS: A total of 236 AFFs (127 dynamically locked and 109 statically locked) were analysed with good interobserver reliability of fracture union assessment (intraclass correlation coefficient = 0.89; 95% CI = 0.82-0.98). AFFs treated with dynamized nails had significantly shorter median TTU (10.1 months; 95% CI = 9.24-10.96 vs 13.0 months; 95% CI = 10.60-15.40) (log-rank test, p = 0.019). Multivariate Cox regression revealed that dynamic locking was independently associated with greater likelihood of fracture union within 24 months (p = 0.009). Reoperations were less frequent in the dynamic locking group (18.9% vs 28.4%), although the difference was not statistically significant (p = 0.084). Static locking was an independent risk factor for reoperation (p = 0.049), as were varus reduction and lack of teriparatide use within three months of surgery. Static locking also demonstrated a higher frequency of treatment failure (39.4% vs 22.8%, p = 0.006) and was an independent predictor of treatment failure in logistic regression (p = 0.018). Other factors associated with treatment failure included varus reduction and open reduction. CONCLUSIONS: Dynamic locking of intramedullary nails in AFFs is associated with faster time to union, lower rate of non-union, and fewer treatment failures.

A Retrospective Review on Atypical Femoral Fracture: Operative Outcomes and the Risk Factors for Failure.

BACKGROUND: Atypical femoral fractures have been demonstrated to have high risks of reoperation and nonunion. The aim of this study is to evaluate whether the quality of reduction following operative fixation of atypical femoral fracture predicts failure. METHODS: This is a 6.5-year retrospective review of atypical femoral fractures from 2 centers in a high-income region. A total of 56 patients with 66 fractures met our inclusion criteria. The quality of reduction was evaluated from postoperative films according to Hoskins' modification of Baumgartner criteria for subtrochanteric fractures. Our primary outcome measure was failure of treatment, defined as either reoperation or nonunion at 12 months. RESULTS: There were a total of 8 reoperations (12% of all fractures) and 8 nonunion (12% of all fractures), affecting a total of 12 fractures (18%) in 12 patients (21%). Closed reduction (P = .04) and poor quality of reduction (P = .0227 Fisher exact test) are statistically significant risk factors for failure. CONCLUSIONS: An aim for anatomical reduction with both <4 mm maximal cortical displacement and <10° angulation can improve the operative outcome of atypical femoral fractures. The addition of open reduction may be beneficial.

Propagation of bisphosphonate-related femoral stress fractures despite femoral nailing: a cautionary tale from 2 cases.

We report 2 cases of atypical femoral fracture displacement despite treatment with intramedullary (IM) nailing. Both patients had received more than 3 years of bisphosphonates. One patient had prophylactic fixation of an atypical femur fracture due to intractable pain. The other had undergone nailing previously for a traumatic shaft fracture. The patient then received bisphosphonate later and sustained an atypical fracture with the nail in place. Both femoral nails were slotted, cannulated stainless steel piriformis entry designs. These 2 cases are among the first reported failures of IM fixation in preventing displacement of a bisphosphonate stress fracture. We advice caution when using slotted nails in prophylaxis of atypical femur fractures because of its significantly reduced torsional stiffness compared to modern nonopen sectioned nails.