Inadequate ‘three-point’ proximal fixation predicts failure of the Gamma nail

Abstract

The Gamma nail is frequently used in unstable peri-trochanteric hip fractures. We hypothesised that mechanical failure of the Gamma nail was associated with inadequate proximal three-point fixation. We identified a consecutive series of 299 Gamma nails implanted in 299 patients over a five-year period, 223 of whom fulfilled our inclusion criteria for investigation. The series included 61 men and 162 women with a mean age of 81 years (20 to 101). Their fractures were classified according to the Modified Evans' classification and the quality of fracture reduction was graded. The technical adequacy of three points of proximal fixation was recorded from intra-operative fluoroscopic images, and technical inadequacy for each point was defined. All patients were followed to final follow-up and mechanical failures were identified. A multivariate statistical analysis was performed, adjusting for confounders. A total of 16 failures (7.2%) were identified. The position of the lag screw relative to the lateral cortex was the most important point of proximal fixation, and when inadequate the failure rate was 25.8% (eight of 31: odds ratio 7.5 (95% confidence interval 2.5 to 22.7), p < 0.001). Mechanical failure of the Gamma nail in peri-trochanteric femoral fractures is rare (< 1%) when three-point proximal fixation is achieved. However, when proximal fixation is inadequate, failure rates increase. The strongest predictor of failure is positioning the lateral end of the lag screw short of the lateral cortex. Adherence to simple technical points minimises the risk of fixation failure in this vulnerable patient group.

Risk factors for intramedullary nail breakage in proximal femoral fractures: a 10-year retrospective review

“…Nonetheless, this figure is consistent with the 0.2-5.6% rate observed in the literature. 4,5,6 This figure is also comparable with the 1.3%…”

“…6 It is, however, a catastrophic event; 23% (5/22) underwent proximal femoral replacement and 9% (2/22) complex arthroplasty procedures for salvage. It is thus important to identify those most at risk.…”

“…The risk engendered by the subtrochanteric fracture may be explained by the observations of Abram et al 6 The group identified radiographic features of Gamma nail fixation which portend fixation failure in peri-trochanteric fractures. Their 16 cases of failure encompassed all modes of failure including implant cut out and subsidence.…”

“…Reported rates of cephalomedullary nail fracture range from to 0.2% to 5.6%. [4][5][6] Given the gravity of the event, it is important to determine patient factors which contribute to and are associated with this form of implant failure. No previous studies have determined patient-specific factors that predisposed to nail fracture.…”

“…6 The authors reported that standard practice involved a single review at 6 weeks following fixation, with discharge for those mobile and pain-free. Patients were only reassessed if they were referred back to clinic.…”