The effect of shortening and varus collapse of the femoral neck on function after fixation of intracapsular fracture of the hip

Abstract

We have studied the effect of shortening of the femoral neck and varus collapse on the functional capacity and quality of life of patients who had undergone fixation of an isolated intracapsular fracture of the hip with cancellous screws. After screening 660 patients at four university medical centres, 70 patients with a mean age of 71 years (20 to 90) met the inclusion criteria. Overall, 66% (46 of 70) of the fractures healed with > 5 mm of shortening and 39% (27 of 70) with > 5 degrees of varus. Patients with severe shortening of the femoral neck had significantly lower short form-36 questionnaire (SF-36) physical functioning scores (no/mild (<5 mm) vs severe shortening (> 10 mm); 74 vs 42 points, p < 0.001). A similar effect was noted with moderate shortening, suggesting a gradient effect (no/mild (< 5 mm) vs moderate shortening (5 to 10 mm); 74 vs 53 points, p = 0.011). Varus collapse correlated moderately with the occurrence of shortening (r = 0.66, p < 0.001). Shortening also resulted in a significantly lower EuroQol questionnaire (EQ5D) index scores (p = 0.05). In a regression analysis shortening of the femoral neck was the only significant variable predictive of a low SF-36 physical functioning score (p < 0.001).

Internal fixation of fragility fracturesof the femoral neck

“…Neck shortening and varus collapse are common following fixation of femoral neck fractures (Zlowodzki et al 2008). Rigid fixations will theoretically increase the risk of implant cut-throughs and cut-outs from the femoral head under repetitive loading.…”

“…In addition to complications requiring new surgery, patients with femoral neck fractures often suffer from lasting reduced physical function and pain (Gjertsen et al 2010. Engesaeter et al 2013), some of which may be due to altered hip biomechanics such as femoral neck shortening (Zlowodzki et al 2008).…”

“…Implant loosening can lead to fracture redisplacements, unphysiological interfragmentary strains with resulting delayed unions, malunions, nonunions (Ragnarsson et al 1993), and fractures around the implant. Femur deformations alter the hip biomechanics which may lead to impaired function, particularly if femoral neck shortening is prominent (Zlowodzki et al 2008).…”

“…Clinically, 5 mm shortening of the femoral neck resulted in impaired function and quality of life (Zlowodzki et al 2008). Considering that only the first postoperative period was simulated in this experiment, 2 mm migration of the femo- ral head center was considered to be large enough to be of potential clinical relevance due to altered hip biomechanics.…”

Diminished abductor muscular strength in patients with valgus-impacted femoral neck fractures treated by internal fixation: Clinical study and biomechanical considerations

“…5 Hip surgeons agree that same length of femoral shortening results in a larger damage for the shorter muscle, and the gluteus medius is shorter than the surrounding major muscles (iliopsoas, gluteus maximus, and quadriceps). 6 In addition, a valgus deformity may weaken abduction due to a relative lateral shift of the femoral head toward gluteus medius. Although measurement of horizontal displacement on radiographs has been reported, 7 visualization may not accurately reflect the three-dimensional (3-D) view of the moment arm.…”