Osteosynthesis of Intracapsular Femoral Neck Fractures by Dynamic Hip Screw (DHS) Fixation

PURPOSE OF THE STUDY The treatment of femoral neck fractures shows a relatively high number of poor outcomes, usually due to late complications, such as avascular necrosis of the femoral head or pseudoarthrosis. The latter may develop when the osteosynthesis of osteoporotic bone fails. The aim of this retrospective study was to evaluate a group of patients treated by osteosynthesis for intra-capsular femoral neck fractures at our department, and to verify indication criteria and identify the therapeutic procedures that are best suited to our conditions. MATERIAL In the 1997-2001 period, a total of 81 patients with intra-capsular femoral neck fractures were operated on. Of these, 64 treated by dynamic hip screw (DHS) fixation were followed up for at least 5 years. There were 33 women and 31 men; the average age was 21.5 years (range, 21 to 74 years). METHODS The Garden classification was used to evaluate the displacement of femoral neck fractures. Preferably, osteosynthesis was carried out by closed reduction; only exceptionally was an extension device for the operating table used. A 135-degree sliding hip screw, with a short thread, directed to the head centre and a two-hole side plate were used most often. The average follow-up was 6.9 years. Evaluated were: the occurrence of late complications in relation to the length of time between injury and surgery, quality of fracture reduction, use of an anti-rotation screw and necessity of repeat surgery. RESULTS Garden I or II fractures were diagnosed in 13 patients, 51 had Garden III or Garden IV fractures. Bone union without complications was achieved in 73.4% of the patients within 12 months of surgery. Late complications were found in 26.6%; of these, only one had Garden I fracture and the rest were Garden III and IV fractures. An anti-rotation screw was used in 39 patients (60.9%) and its use had no effect on the development of late complications. Of the seven patients who developed pseudoarthrosis, the screw was used in four (57.1%); out of the nine patients with avascular necrosis, it was used in six (66.7%). In the whole group, an unsatisfactory outcome of post-operative reduction was recorded in 29.7%. in the patients with late complications this was found in 52.9%, which was a statistically significant difference. Of the 17 patients with poor outcomes, 14 underwent total hip arthroplasty; in the patients with necrosis, arthroplasty was carried out at an average of 26 months post-operatively, in those with pseudoarthrosis it was at 7 months post-operatively. DISCUSSION For the treatment of intra-capsular fractures of the femoral neck, surgery is the most frequent approach, but there are controversial views on various relevant issues. An important factor affecting the treatment outcome is the patient's bone quality. CONCLUSIONS Our results show a direct relationship between the extent of fracture displacement and late complications, i.e., avascular necrosis and non-union. The quality of fracture reduction had a greater effect on fracture non-union than on the development of femoral head necrosis. The length of time between injury and surgery played a lesser role than it is believed. The use of an anti-rotation screw was not significantly related to the occurrence of late complications. The DHS method is economical and available, and provided sufficient results whose comparisons with the literature data show that this therapeutic approach is correct.