Abstract
Background
In total hip arthroplasty (THA), preservation of the short external rotator muscles are considered to be important because they contribute to joint stability and prevent postoperative dislocation. Recently, we reported that there are bony impressions on the greater trochanter that indicate the insertions of the short external rotator tendons. In this study, we reported a method to visualize the bony impressions using preoperative CT images, and evaluate the reliability and accuracy of this method.
Methods
Thirty-three hips from 24 consecutive patients undergoing THA were enrolled. The mean age was 65.3 years. Preoperative diagnoses included hip osteoarthritis in 27 hips, rheumatoid arthritis in 4 hips, idiopathic osteonecrosis in 1 hip, femoral neck fracture in 1 hip. Preoperative CT of the hip region was obtained and three-dimensional (3D) reconstruction of the greater trochanter was performed to visualize the bony impressions, that we called the obturator tendon attachment (OTA), indicating the attachment area of the obturator internus and externus muscles.
Results
3D reconstructed images of the greater trochanter were observed from medial side at 50 degrees of external hip rotation and 20 degrees of abduction (OTA view). Using OTA view, the bony impressions indicating the attachment area of the obturator internus and externus muscles can be identified in all hips.
Conclusions
The bony impressions indicating the attachment area of the obturator internus and externus muscles can be visualized using preoperative 3D-CT. We considered that the findings in the present study could be helpful for surgery because the alignment of the short external rotator muscles can be estimated preoperatively and the extent of the damage to the OA during the rasping or reaming can be estimated.
