A comparative study between double-threaded compression screws and cannulated lag screws for fixation of Garden typeI/IIfemoral neck fractures

Abstract

Objective To compare the results between double-threaded compression screws and cannulated lag screws for Garden type I/II femoral neck fractures. Methods Data of 56 patients with Garden type I/II femoral neck fractures who were treated with internal fixation from July 2012 to March 2016 were retrospectively analyzed. According to different fixation, the patients were divided into two groups: double-threaded screws group (group A) including 27 cases (7 males and 20 females, with an average age of 55.5±10.0 years, 14 cases Garden type I and 13 cases Garden type II, the proportion of osteoporosis 10/27; And lag screws group (group B) including 29 cases (8 males and 21 females, with an average age of 57.2±9.5 years, 11 cases Garden type I and 18 cases Garden type II, the proportion of osteoporosis 15/29. The 2 groups were compared with respect to bony fusion time, nonunion, avascular necrosis of femoral head, shortening of femoral neck and Harris Hip Score. Results The average follow-up time was 20.3±8.7 m in Group A and 24.5±7.9 m in Group B. The average bony fusion time was 5.3±0.6 m in Group A and 4.1±0.8 m in Group B, and there was significant difference between the groups (t=5.758, P=0.00). 1 avascular necrosis of femoral head was found in both groups. In group A, there were 3 cases of bone nonunion (11.1%, 3/27). There were one bone nonunion (3.4%, 1/29) case in group B, with no statistically significant difference between groups. Shortening of femoral neck occurred in both groups, the average horizontal shortening was 5.8±2.9 mm and vertical shortening 7.0±3.4 mm in Group A, which were lower than group B (8.2±3.1 mm, 9.4±3.6 mm), and the differences showed statistically significant (t=-2.94, P=0.005; t=-2.48, P=0.016) . In group A, the average Harris Hip score was 88.2±8.3, while that in group B was 89.9±7.2. There was no statistically significant difference between two groups. Conclusion It seems to us that in the treatment of Garden type I/II femoral neck fractures, double-threaded compression screws fixation could reduce femoral neck shortening, but there is no difference on functional outcome compared to cannulated lag screws fixation. On the contrary, double-threaded compression screws fixation is not conducive to fracture healing due to lack of sliding compression. Key words: Femoral neck fractures; Fracture fixation, internal; Bone screws