Finite element analysis of cannulated screw internal fixatio
Femoral neck fracture is one of the most common bone types. A Study was conducted to investigate the clinical efficacy and mechanical mechanism of positive buttress, anatomical reduction, and negative buttress in the treatment of femoral neck fracture after cannulated screw fixation.

Retrospective analysis of patients with femoral neck fracture treated with three cannulated screws internal fixation was done. According to the quality of fracture reduction, the patients were divided into positive buttress group, anatomical reduction group, and negative buttress group. Basic information such as injury mechanism, time from injury to surgery, Garden classification and Pauwels classification was collected, Harris scores were performed at 3 months, 6 months, and 12 months after surgery, and postoperative complications were collected.

Results:
--A total of 225 cases of unilateral femoral neck fractures were included and followed up for an average of 4.12 ± 0.69 years.

--There was no significant difference in age, gender, side, injury mechanism, time from injury to surgery, BMI, Garden classification, Pauwels classification, and follow-up time among the three groups.

--However, there was significant difference in Harris score at 6 and 12 months after operation among the three groups, which was higher in the positive buttress group and anatomical reduction group than in the negative buttress group.

--In addition, the incidence of osteonecrosis of the femoral head in the negative buttress group was greater than that in the anatomical reduction group and the positive buttress group.

--In addition, the incidence of femoral neck nonunion and femoral neck shortening in the negative buttress group was also higher than that in the anatomical reduction positive buttress group.

--The finite element results showed that the stress and fracture end displacement in the negative buttress group were greater than those in the positive buttress group.

In short, a better clinical and reduced postoperative problems can be achieved, both positive and anatomical reductions in the treatment of femoral neck fractures by the cannulated internal vibration fixation. The restitution of femoral stress conduction might be limited by a positive bracelet and anatomical reduction. Therefore, anatomical reduction is not necessary during surgery too purposefully, while a reduction in the backrest should be prevented.

Source: https://josr-online.biomedcentral.com/articles/10.1186/s13018-021-02580-6
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