The optimal positioning of the acetabular component is a relevant prognostic factor in total hip arthroplasty (THA). Because of substantial errors of manual technique in cup placement even with experienced surgeon, computer aided navigation system has been developed in recent years. However, existence of the hardware around acetabulum likely deteriorates the accuracy of the navigation system, namely in revision THA case and postoperative status of pelvic fracture. Here we report a case who we successfully performed THA using CT based navigation system although there were multiple hardware around acetabulum due to osteosynthesis for the previous pelvic fracture. A forty-one years old man presented with intolerable hip pain with severe radiographic osteoarthritic findings in left hip joint. He had sustained left pelvic fracture and posterior hip dislocation due to traffic accident and undergone osteosynthesis using multiple plates and screws when he was forty years old. However, progressive collapsing of femoral head and acetabulum occurred. Then, we indicated THA for his situation and planned to apply the CT based navigation system (Stryker CT based hip Ver.1.1 softwear and Cart II system). Preoperative workup revealed incomplete union of posterior and superior acetabular wall and we had to retain plates and screws for the stable fixation of acetabular cup. The existence of the hardware made it complicated to perform three dimensional planning and templating. Meticulous surface editing of pelvis to exclude the metal artifact and fibrocartilagenous tissue was needed to achieve accurate surface registration. In the operation room, we had to use unusual way of registration to complete two steps of registration. In the first step (roughly matching between patient's physical pelvic surface and edited pelvic surface in work station using corresponding 5 points), we utilized head of screw and hole of the plate which we could easily identify intraoperatively, in addition to ASIS and innominate groove. In the second step (strict matching using more than 30 points of pelvic surface), we had to identify the pelvic bony surface, as excluding the metal surface and fibrocartilagenous tissue such as fracture callus. These efforts enabled us to accomplish substantial accuracy of registration with RMS of 0.5 mm. Final cup orientation at the end of surgery was 41° of inclination and 25° of anteversion. Postoperative CT scan revealed that cup placement angle was 40° of inclination and 25° of anteversion, almost identical with intraoperative value.Objective
Case presentation
Optimal orientation of the acetabular cup is vital issue not only for primary but revision total hip arthroplasty (THA). Especially in revision THA, malorientation of the cup is likely to occur because anatomical landmark around acetabular rim often disappeared by the osteolytic bony destruction or the process of cup removal. As a consequence, higher dislocation rate and accelerated wear of bearing surface compared with primary THA, which affect the outcome of revision THA, are concerned. On the other hand, computer aided navigation system has been developed in recent years because of substantial errors of manual technique in cup placement even with experienced surgeon. The purpose of this study was to evaluate the accuracy of the cup orientation in revision cementless THA using CT based navigation system. Thirteen patients who underwent revision cementless THA with CT based navigation system (Stryker Japan) were employed for this study. The average age at surgery was 64 years (range, 45–78 years, 3 men and 11 women). Primary surgery was cementless THA in 4 and BHA in 9 hips. Disorder which led to revision THA was loosening of the cup, massive retroacetabular osteolysis, and severe proximal migration of bipolar outer head. In most cases, acetabular rim was not conserved. After removal of the cup or outer head, we revised acetabular components with cementless hemispherical TriAD cups (Stryker Japan) using direct lateral approach in lateral decubitus position. For all the patients, post-operative CT scans were performed and the cup inclination and anteversion angle were measured using 3D image-processing software (Stryker, Japan). The difference between the intra-operative target angle and the angle measured from the post-operative CT image were calculated.Introduction
Materials and Methods
Herniation pits had been considered as a normal variant, a cystic lesion formed by synovial invagination. On the contrary, it was also suggested that herniation pits were one of the diagnostic findings in femoroacetabular impingement (FAI) because of the high prevalence of herniation pits in the FAI patients. To date, the exact etiology is still unknown. The purpose of this study was to evaluate whether there is an association between the presence of herniation pits and morphological indicators of FAI based on computed tomography (CT) examination. We reviewed the CT scans of 245 consecutive subjects (490 hips, age: 21–89 years) who had undergone abdominal and pelvic CT for reasons unrelated to hip symptom from September, 2010 to June, 2011. These subjects were mainly examined for abdominal disorders. We confirmed by the questionnaire survey that there were no subjects who had symptoms of hip joints. We reviewed them for the presence of herniation pits and the morphological abnormalities of the femoral head and acetabulum. Herniation pits were diagnosed when they were located at the anterosuperior femoral head-neck junction with a diameter of more than 3 mm. We measured following four signs as indicators for FAI: α angle, center edge angle (CE angle), acetabular index (AI), and acetabular version. Mann-Whitney U-test was used for statistical analysis.Introduction
Materials and methods
Hip Arthrodesis had been considered as a useful surgical option in young adult patient with high activity demands suffering from osteoarthritis of the hip. Although the procedure surely eliminates pain of the hip joint, it can also cause disorders of the adjacent joints in addition to the complete loss of motion, might consequently deteriorate the activity of daily living. The purpose of this retrospective study was to investigate the efficacy and drawback of hip arthrodesis, focusing on the effect of this procedure on the adjacent joints. From 1976 to 1989, 29 hip arthrodesis were performed and 22 hips were followed up (1 died, 6 lost). Disorders led to arthrodesis were septic arthritis (1 hip), post-traumatic (1), osteonecrosis (1), primary osteoarthritis (3), and secondary osteoarthritis due to DDH (16). The average age at surgery was 38 years (range, 19–53 years, 6 men and 16 women). Hip arthrodesis was indicated for young active adults with end stage osteoarthritis, who had normal or mild osteoarthritis in contralateral hip and needed physical labor. The hip was positioned in 30 degrees of flexion, 0 to 5 degree of external rotation, and 0 to 5 degree of abduction. Clinical and radiographic assessment was done for these patients. The clinical follow-up consisted of questionnaire which assessed ability of typical Japanese daily living movement and patient's satisfaction. The condition of the adjacent joints was evaluated clinically and radiographically.Introduction
Materials and Methods
Vascular injury associated with hip surgery is a rare but serious complication. Hip surgeons need to understand the vascular anatomy around the acetabulum to avoid vascular injury. The aim of this study was to visualize the pelvic vascular structures thorough the osseous acetabulum using 3DCT angiography and to describe the three-dimensional relationship between the vessels and the acetabulum. A total of 100 patients who took 3DCT with intravenous contrast for intra-pelvic neoplastic disease were randomly chosen. Those patients with hip disease were excluded. Three examinations were performed. First, dual-phase helical CT data were transferred to a workstation (M900;Zio,Tokyo,Japan) and 3D visualizations of the vascular structures through the pelvis were reconstructed. Second, location of the external iliac, femoral and obturator vessels were investigated in axial CT images. Finally, influence of the age factor on the anatomical courses of the external iliac vessels was assessed. Reconstructed 3D images were able to provide spatial relationship between courses of the pelvic vascular structures and the acetabulum. We could visualize the pelvic vascular structures thorough the pelvis from similar operative viewpoints. Axial CT examinations revealed the external iliac vessels locate very closely to the pelvis as they exit the pelvic cavity. Especially, the left side vessels and vein were closer to the pelvis. The femoral vessels became closer to the acetabular edge with traveling distally. At the distal half of the acetabulum, the femoral vessels located just ventrally to the anterior acetabular edge. The obturator vessels courses inferiorly along the quadrilateral surface behind the acetabulum, they became very close to the inner cortex or the acetabulum. Straight type of the anatomical course of the external iliac vessels was the most common configuration in young patients, curved and the tortuous types were present in older patients. The results of this study are useful to understand the anatomical orientation of the vessels around the acetabulum. To avoid vascular injuries in hip surgery, knowledge of the vascular orientation is of critical importance for the hip surgeon.
