Orthopaedic robot-assisted free vascularised fibular grafting for the treatment of avascular necrosis of the femoral head

Objective To introduce the surgical procedure of orthopaedic robot-assisted vascularised fibular grafting for the treatment of ANFH and report the short-term result. Methods From September, 2016 to November, 2018, 17 patients (21 hips) with ANFH had undergone robot-assisted free fibular grafting. There were 14 males and 3 females, of which, 8 cases were associated with the right side, 5 cases the left side, and 4 cases with both sides. The average age was 35 (ranged from 17 to 55) years. There were 7 patients suffered from idiopathic ischemic necrosis of femoral head, 4 patients who had cannulated screws fixed after a femoral neck fracture, 4 patients who had a history of alcohol consumption, 1 patient who had taken corticosteroids for 6 months to treat nephritis, and 1 patient who had a history of alcohol consumption and had also taken corticosteroids. Seventeen hips were in Ficat stage II, and 4 hips were in Ficat stage III. The orthopaedic surgical robot workstation was used to plan the entry point and target of the guide pin during the operation, to place a cannula in the optimal position. Then a bone window was created and the fibula was placed into the bone tunnel. Using fluoroscopy to monitor each step of the procedure and verify the position of the fibula. Finally, the vessels were anastomosed. The patient remain in bed completely for a week with the use of vasodilator. The follow-up was accomplished with phone call and outpatient clinic, and Harris score was evaluated. Results All 21 surgical procedures were successful. The guide pins and fibula were accurately placed according to the robot’s plan, and the tips of the fibula were placed at the centre of the load-bearing region of the femoral heads, 4 to 6 mm from the articular surface. Conventional anticoagulant, anti-infective therapy was performed after the procedure. Ten patients were followed-up postoperatively more than 1 year, with an average of 15 (from 12 to 24) months. The function of the hip joint recovered smoothly for 9 patients. Frontal and lateral X-ray and CT scans showed that the tips of the fibula were placed at the centre of the load-bearing region, 4 to 6 mm from the articular surface. One patient suffered from bilateral femoral head necrosis and the right side recovered smoothly after operation. However, joint movement was restricted for the left hip and the pain was significant. An arthroscopic examination was performed 1 month after the operation and did not identify any problems such as intraarticular incular infection or articular surface of the femoral head was protruded by the tip of the fibula. The symptoms were alleviated after removing the osteophytes at the rim of the acetabulum. The Harris score was 62.4±13.6 before operation, and 84.5±4.5 at the last time of followed-up after operation. The difference in Harris scores was statisticly significant (P<0.05). Conclusion With the assistance of an orthopaedic robot system, the guide pin can be accurately positioned, thereby allowing the tip of the fibula to be inserted into the optimal anatomical position and maximising its mechanical efficacy. In theory, it is the best choice for performing fibular bone transplantation in ANFH. And the early effect of treatment is good. Key words: Avascular necrosis of femoral head; Orthopaedic robot; Fibula grafting; Microsurgical technique