Comparison of full thread compression cannulated screw and partial thread cannulated screw in treatment of femoral neck fracture

Abstract

To compare the effectiveness of full thread compression cannulated screw and partial thread cannulated screw in the treatment of femoral neck fracture. A retrospective analysis was made on 152 patients with femoral neck fractures, who met the selection criteria, between April 2013 and February 2021. The fractures were fixed with the full thread compression cannulated screws in 74 cases (trial group) and the partial thread cannulated screws in 78 cases (control group). There was no significant difference in general data such as age, gender, body mass index, cause of injury, time from injury to operation, and the side, Garden typing, Pauwels typing of fracture between the two groups (P>0.05). The operation time, intraoperative blood loss, hospital stay, follow-up time, and Harris score were recorded in both groups. X-ray films were performed to evaluate the quality of fracture reduction and bone healing, the changes of neck-shaft angle, the changes of femoral neck, as well as the occurrence of internal fixation failure, screw back-out, and osteonecrosis of the femoral head. There was no significant difference in operation time and hospital stay between the two groups (P>0.05). However, the intraoperative blood loss in the trial group was significantly lower than that in the control group (P<0.05). Patients in both groups were followed up, with the follow-up time of (24.11±4.04) months in the trial group and (24.10±4.42) months in the control group, and the difference was not significant (P>0.05). Postoperative X-ray films showed that there was no significant difference in fracture reduction grading between the two groups (P>0.05). Six cases in the trial group developed bone nonunion and 7 cases in the control group, the fractures of the other patients healed, and the healing time was significantly shorter in the trial group than in the control group (P<0.05). There was no significant difference in the incidence of bone nonunion between the two groups (P>0.05). During follow-up, 2 cases in the trial group and 5 cases in the control group had osteonecrosis of the femoral head, the difference was not significant (P>0.05), and the patients with osteonecrosis of the femoral head were treated with secondary operation. The screw back-out occurred in 3 cases of the trial group and in 9 cases of the control group, showing no significant difference (P>0.05). But the screw back-out distance was significantly shorter in the trial group than in the control group (P<0.05). The incidence of internal fixation failure in the trial group (4 cases) was significantly lower than that in the control group (14 cases) (P<0.05). The incidence of femoral neck shortening and the change of neck-shaft angle at 1 year after operation were significantly lower in the trial group than in the control group (P<0.05). The Harris score at last follow-up was significantly higher in the trial group than in the control group (P<0.05). Compared with the partial threaded cannulated screws, the full threaded cannulated compression screws can effectively maintain fracture reduction, avoid femoral neck shortening, and internal fixation failure. It is a better choice for femoral neck fracture.