Objective: To provide guidance for hip replacement by analyzing the variation of femoral head rotation center in different hip diseases.
Methods: A total of 5 459 patients were collected from March 2016 to June 2021, who took positive and proportional plain films of both hips for various reasons. The relative position between the rotation center of the femoral head and the apex of the greater trochanter was measured. The positive variation is more than 2 mm above the top of the great trochanter, and the negative variation is more than 2 mm below the top of the great trochanter. A total of 831 patients with variation of femoral head rotation center were collected and were divided into 4 groups according to different diseases, and the variation was counted respectively. There were 15 cases in the normal group involving 10 cases of positive variation and 5 cases of negative variation. There were 145 cases of avascular necrosis of femoral head involving 25 cases of positive variation and 120 cases of negative variation. There were 346 cases of congenital hip dysplasia involving 225 cases of positive variation(including 25 cases of typeⅠ, 70 cases of type Ⅱ, 115 cases of type Ⅲ and 15 cases of type Ⅳ), and 121 cases of negative variation(including 50 cases of crowe typeⅠ, 60 cases of typeⅡ, 10 cases of type Ⅲ and 1 case of type Ⅳ). There were 325 cases of hip osteoarthritis group involving 45 cases of positive variation and 280 cases of negative variation.
Results: There was significant difference in variation of femoral head rotation center among the four groups(P<0.05). There was significant difference in variation of femoral head rotation center among different types of congenital hip dysplasia(P<0.05). There were significant differences in cervical trunk angle and eccentricity among different variations of femoral head rotation center(P<0.05).
Conclusion: The variation of femoral head rotation center is related to cervical trunk angle and eccentricity. The variation of femoral head rotation center is an important factor in hip diseases. The variation of femoral head rotation center is different in different hip diseases. Avascular necrosis of the femoral head and osteoarthritis of the hip were mostly negative variations. With the aggravation of congenital hip dysplasia, the variation of femoral head rotation center gradually changed from negative variation to positive variation.The variation of femoral head rotation center should be paid attention to in the preoperative planning of hip arthroplasty. It is of great significance to select the appropriate prosthesis and place the prosthesis accurately.
Keywords: Arthriplasty, replacement, hip; Femoral head necrosis; Hip dislocation, congenital; Variation of femoral head rotation center.