Heterotopic ossification around the knee after tibial nailing and ipsilateral antegrade and retrograde femoral nailing in the treatment of floating knee injuries

Purpose: Floating knee injuries are relatively uncommon injuries. We report the prevalence, location, and severity of heterotopic ossification (HO) around the knee in patients treated with antegrade tibial intramedullary nailing and ipsilateral antegrade versus retrograde femoral intramedullary nailing as well as how the severity of HO around the knee affects knee range of motion (ROM). Methods: From 2004 to 2014, 26 floating knee injuries were included. Radiographs were reviewed to determine presence, location, and severity of HO. Post-operative knee ROM was determined. Results: A significantly higher prevalence of HO around the knee was detected in the retrograde group (90%) compared to the antegrade group (43%) (p = 0.028). There was a trend for more HO into the patellar tendon occurring in 29% of patients in the antegrade group and 74% in the retrograde group (p = 0.069). The severity of HO was higher for the retrograde group 1.6 ± 1.0 compared to the antegrade group 0.4 ± 0.5 (p = 0.004). There was poor correlation between HO severity and knee ROM. Conclusions: Treatment of floating knee injuries with a retrograde femoral nail was demonstrated to result in a greater likelihood of developing HO and a greater severity of HO around the knee than if treated with an antegrade femoral nail. However, this increased severity of HO is unlikely to affect ROM. Level of evidence: III.