[Effectiveness of guide plate with mortise-tenon joint structure combined with off-axis fixation in treatment of Pauwels type Ⅲ femoral neck fractures].

Objective: To investigate the effectiveness of using 3 hollow compression screws combined with 1 screw off-axis fixation under the guidance of three-dimensional (3D) printed guide plate with mortise-tenon joint structure (mortise-tenon joint plate) for the treatment of Pauwels type Ⅲ femoral neck fractures.

Methods: A clinical data of 78 patients with Pauwels type Ⅲ femoral neck fractures, who were admitted between August 2022 and August 2023 and met the selection criteria, was retrospectively analyzed. The operations were assisted with mortise-tenon joint plates in 26 cases (mortise-tenon joint plate group) and traditional guide plates in 28 cases (traditional plate group), and without guide plates in 24 cases (control group). There was no significant difference in the baseline data of gender, age, body mass index, cause of injury, and fracture side between groups ( P>0.05). The operation time, intraoperative blood loss, frequency of intraoperative fluoroscopy, incision length, incidence of postoperative deep vein thrombosis of lower extremity, pain visual analogue scale (VAS) score at 1 week after operation, and Harris score of hip joint at 3 months after operation were recorded and compared. X-ray re-examination was taken to check the quality of fracture reduction, fracture healing, and the shortening length of the femoral neck at 3 months after operation, and the incidences of internal fixation failure and osteonecrosis of the femoral head during operation.

Results: Compared with the control group, the operation time, intraoperative blood loss, and frequency of intraoperative fluoroscopy reduced in the two plate groups, and the quality of fracture reduction was better, but the incision was longer, and the differences were significant ( P<0.05). The operation time and intraoperative blood loss were significantly higher in the traditional plate group than in the mortise-tenon joint plate group ( P<0.05), the incision was significantly longer ( P<0.05); and the difference in fracture reduction quality and the frequency of intraoperative fluoroscopy was not significant between two plate groups ( P>0.05). There was 1 case of deep vein thrombosis of lower extremity in the traditional plate group and 1 case in the control group, while there was no thrombosis in the mortise-tenon joint plate group. There was no significant difference in the incidence between groups ( P>0.05). All patients were followed up 12-15 months (mean, 13 months). There was no significant difference in VAS score at 1 week and Harris score at 3 months between groups ( P>0.05). Compared with the control group, the fracture healing time and the length of femoral neck shortening at 3 months after operation were significantly shorter in the two plate groups ( P<0.05). There was no significant difference between the two plate groups ( P>0.05). There was no significant difference in the incidences of non-union fractures, osteonecrosis of the femoral head, or internal fixation failure between groups ( P>0.05).

Conclusion: For Pauwels type Ⅲ femoral neck fractures, the use of 3D printed guide plate assisted reduction and fixation can shorten the fracture healing time, reduce the incidence of postoperative complications, and be more conducive to the early functional exercise of the affected limb. Compared with the traditional guide plate, the mortise-tenon joint plate can reduce the intraoperative bleeding and shorten the operation time.