INTERNAL FIXATION OF INTRACAPSULAR NECK OF FEMUR FRACTURES: TWO-HOLE SLIDING HIP SCREW OR CANNULATED HIP SCREWS?

Background Intracapsular neck of femur fractures are one of the most common injuries seen in Orthopaedics. When the fracture is amenable to internal fixation there are 2 main treatment options, namely multiple cannulated hip screws (MCS) and 2-hole sliding hip screws (SHS). In this retrospective study we examine the outcomes associated with these two methods of internal fixation. At present there is little consensus regarding which treatment should be used Methods 161 patients were found to have suffered intracapsular neck of femur fracture treated with either SHS or MCS fixation over a 5 year period from April 2009 to April 2014, allowing at least 1 year follow up following injury. The patients imaging and clinical notes were then reviewed to ascertain the outcome of their treatment and any complications. Results 93 patients were treated with a sliding hip screw compared to 68 that had been treated with cannulated screws. To ensure the fractures in each group were comparable in terms of fracture severity they were classified using gardens and pauwels score. The mean age of the group treated with SHS was 75.15 years, 7.69 years higher than those treated with MCS. The mean length of inpatient stay was 4.7 days longer for patients treated with sliding hip screws than those treated with cannulated screws, which is significantly more than would be predicted by age difference alone. Further patients were excluded for analysis of failure rate if they had not been sufficiently followed up, leaving 122 patients, 58 treated with MCS and 64 with SHS. A significantly higher (p=0.0136) proportion of patients treated with SHS (32%) suffered failure of their fixation compared to those treated with MCS (10%). The SHS group was further classified by whether or not a permanent derotation screw was employed. The use of a derotation screw provided protection against failure with a number needed to treat of 3.82, decreasing the failure rate to 14% which was not significantly more than the failure rate for MCS. Conclusions We recommend that the first choice treatment for intracapsular neck of femur fractures amenable to internal fixation should be cannulated screws due to a lower rate of failure and shorter length of inpatient stay. If a surgeon has a strong preference for sliding hip screw we strongly recommend inserting a permanent derotation screw.