Postoperative subtype P as a risk factor for excessive postoperative sliding of cephalomedullary nail in femoral trochanteric fractures in old patients: A case series of 263 patients using computed tomography analysis

Abstract

Introduction: Although excellent results of cephalomedullary nailing for femoral trochanteric fractures have been reported, excessive sliding has recently been noted as a cause of lag screw cut-out. Excessive sliding is reported as sliding of ≥8mm, which occurs in approximately 40%of cases. This study aimed to evaluate the risk factors for excessive sliding.

Patients and methods: Overall, 551 patients who underwent cephalomedullary nail surgery between 2016 and 2021 were recruited. Patients aged ≥65 years who underwent preoperative computed tomography (CT), experienced low-energy trauma, and received follow-up for >4 months were included. Cases were retrospectively reviewed for their postoperative sliding distance and the percentage of excessive sliding (>8 mm). 3D-CT classification, reduction pattern (subtypes A, N, and P) in the lateral view, medullary mismatch, and implant type (short/long Gamma3 nail and INTERTAN) were investigated fortheirimpact on sliding distance andtheincidence of excessive sliding. Complication rates (lag screw cut-out and non-union) were also assessed.

Results: Overall, 263 patients (mean age, 84.0±7.4; 186 women) were recruited. The median (range) sliding distance was 3.5 (0-20) mm, and 42 cases (16.0%) had excessive sliding. Sliding distance was significantly smaller in the 2-fragment group than in the 3-fragment group (GP+GA and GP+L) (p=0.02); however, there were no significant differences between the 2-fragment and other fracture-type groups, including the 3-fragment group (GP, GA, GP ± GA, GP ± L), 4-fragmentgroup(GP/L, GP ± L/GA, GP±GA/L), and 5-fragmentgroup. There was no significant difference in sliding distance according to postoperative reduction type between the groups (p=0.83) and no correlation between medullary mismatch and sliding distance. The amount of sliding and rate of excessive sliding were significantly lower in the INTERTAN group than in the Gamma3 nail groups (p<0.01). Logistic regression analysis with excessive sliding as the variable revealed reduction type P as the only risk factor (p=0.024, odds ratio 2.99). There were three lag screw cut-out (1.1%) cases and one non-union (0.4%) case.

Conclusions: Postoperative subtype P is a risk factor for excessive sliding; there was significantly less sliding in the INTERTAN nail group. It is necessary to avoid reduction to subtype P to prevent postoperative excessive sliding.

Level of evidence: IV.

Keywords: CT classification; excessive sliding; femoral trochanteric fracture; short femoral nail; telescoping.