Intraoperative lateral wall fractures during Dynamic Hip Screw fixation for intertrochanteric fractures-Incidence, causative factors and clinical outcome

Abstract

IntroductionThe intact lateral wall plays a key role in stabilization of trochanteric fracture. Hence extreme precaution should be taken to prevent lateral wall damage during DHS fixation. Present study is aimed at evaluating the determinants of lateral wall fracture and its effect on outcome in intertrochanteric fracture femur treated with DHS. Material and methodsThis is a prospective study involving intertrochanteric fractures treated with DHS fixation from July 2013 to June 2014. Out of 135 patients 49(36.3%) had stable fractures and 86(63.7%) unstable fractures. Cortical thickness index (CTI) was measured to evaluate osteoporosis. Lateral wall thickness in anteroposterior radiograph was also measured.All patients underwent 135° DHS fixation.Postoperative x-rays are assessed for implant position, intactness of the lateral wall, tip apex distance (TAD) and medialization. Functional outcome was measured at the end of fracture union by modified Harris hip score and Parkers mobility score. Clinical information including age, gender, fracture classification, TAD, lateral wall thickness and functional outcome of the patients were subjected to statistical analysis. Results34 (19.5%) patients had lateral wall fractures. Medialization was found in 22 out of these 34 (64.7%) patients. The mean preoperative lateral wall thickness of these patients is 19.2mm, compared with 26.8mm in patients with intact lateral wall (p<0.001). The mean values of CTI and TAD are comparable in both the groups. In patients with intact lateral wall, mean Harris hip score is 73.1 compared to 65.5 in lateral wall fracture group (p<0.001). Preinjury mobility status was achieved in 70.2% of intact lateral wall patients, whereas only 32.3% (11) achieved that in lateral wall fracture group. Threshold for lateral wall thickness that could predict lateral wall fracture was found to be 21mm with 95% sensitivity and 88.2% specificity. ConclusionLateral wall fractures during DHS fixation are not uncommon and osteoporosis has no bearing on its occurrence. It alone can lead to poor radiological and functional outcome independent of TAD. Lateral wall thickness is a reliable predictor of intra operative lateral wall fracture during DHS fixation and nailing is a good option especially when lateral wall thickness is <21mm.