Abstract: BACKGROUND: The prognosis of dynamic hip screws versus proximal rotation-proof intramedullary nailing for the treatment of intertrochanteric fractures has been discussed previously. However, there is a lack of comparative long-term prognostic studies on the conversion to hip arthroplasty after failure of internal fixation with both procedures.  
OBJECTIVE: To compare the long-term clinical outcomes after conversion to hip arthroplasty following failed treatment of stable intertrochanteric fractures with dynamic hip screws versus proximal femoral nail anti-rotation.
METHODS:  Between January 2012 and April 2017, data of 102 elderly patients treated at Hebei Petro China Center Hospital were retrospectively analyzed. Fifty of these patients were included in the dynamic hip screws group, which was the group converted to treatment with conversion to hip arthroplasty after failure of dynamic hip screw for stable femoral intertrochanteric fractures, and 52 in the proximal femoral nail anti-rotation group, which was the group converted to treatment with conversion to hip arthroplasty after failure of proximal femoral nail anti-rotation for stable femoral intertrochanteric fractures. Clinical indicators (Harris score) and imaging results at least 3 years after surgery were compared between the two groups.  
RESULTS AND CONCLUSION: (1) The surgery was completed successfully in both groups, and no nerve or vascular injury occurred intraoperatively in either group. (2) There were no significant differences between the two groups in terms of age, gender, cause of internal fixation failure, ASA grading, mode of fixation of the femur, follow-up time and fracture typing of the intertrochanteric fracture of the femur (P > 0.05). (3) There was no significant difference in the Harris score of the hip joint before and after each follow-up between the two groups of patients (P > 0.05). (4) The overall postoperative complication rate was 48.0% (24/50) in the dynamic hip screws group compared to 21.2% (11/52) in the proximal femoral nail anti-rotation group, with a statistically significant difference between the two groups (P < 0.05). The incidence of orthopedic complications was 32.0% (16/50) in the dynamic hip screws group compared to 13.7% (7/52) in the proximal femoral nail anti-rotation group at the time of final follow-up, with a statistically significant difference between the two groups (P=0.025). (9) Nine postoperative periprosthetic fractures were noted in the dynamic hip screws group compared to two in the proximal femoral nail anti-rotation group, with a statistically significant difference between the two groups (P=0.021). (6) Above results confirm that conversion to hip arthroplasty after failed dynamic hip screws treatment has a higher orthopedic complication rate than conversion to hip arthroplasty after failed proximal femoral nail anti-rotation, especially periprosthetic fractures. Thus, conversion to hip arthroplasty is more suitable for treatment after failed internal fixation in proximal femoral nail anti-rotation than after failed internal fixation in dynamic hip screws.

Key words: hip, joint, hip replacement, intertrochanteric fracture, proximal femoral nail anti-rotation, dynamic hip screw, internal fixation failure, periprosthetic fracture