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Background If the bony region indicating the ilioischial line is established on the preoperative axial computed tomography (CT) image, the distance between the simulated cup and the ilioischial line can be measured on this image so that the surgeon can use these data to define a more accurate preoperative two-dimensional (2D) template of total hip arthroplasty (THA). This study aimed to verify the hypothesis that on the CT axial image, the cortical bone area, indicated by the superimposition of a line (line α) with a perspective projection angle to the ilioischial line on radiography and tangent to the medial acetabular wall, is the cortical bone that represents the ilioischial line on radiography. Methods Study 1: If the two measured distances (distance A’ and distance B) are sufficiently equal, then the hypothesis can be supported. Distance A’ was calculated by multiplying the distance A, between the ilioischial line and the medial margin of the metal cup after THA measured at the level of the hip joint center on the pelvic radiograph, by 0.91 to correct for radiographic magnification. Distance B was defined as the distance between the medial margin of the metal cup and line α on the axial CT image at the level of the hip joint center. These two distances were measured for all 51 hip joints included in the study. Study 2: The difference between distance A and distance A# (distance A on the 2D template) was compared between the group containing 59 primary THAs in which distance B′ was measured (distance B in the simulation) and the control group containing 59 primary THAs. Results Study 1: The average distance for A’ was 4.5 ± 2 mm, and the average distance for B was 4.7 ± 2.1 mm. The difference between distances A and B was 0.2 ± 0.2 mm. Study 2: The mean difference between distance A and distance A# for the measurement and control groups was 1.8 ± 1.3 mm and 3.7 ± 2.4 mm, respectively (P < 0.001). Conclusions The ilioischial line is located in the bony region where line α intersects the medial acetabular wall with a maximum overlap on axial CT images.

Myxoinflammatory fibroblastic sarcoma (MIFS) is a rare, painless, and intermediate (rarely metastasizing) fibroblastic tumor, which commonly occurs in the extremities, with an equal sex predilection. This sarcoma is composed of a mixed inflammatory infiltrate along with spindled, epithelioid, and bizarre tumor cells in a background of hyaline and myxoid areas. In spite of such a distinctive morphology, the tumor can be a diagnostic challenge, simulating inflammatory conditions as well as neoplastic nature. For accurate diagnosis, the tumor requires extensive clinical, radiological, and pathological investigations. We present a case of MIFS in a 19-year-old female who presented with a mass in the left ankle. After appropriate excision and postoperative radiation therapy, she is free of disease, including recurrence and metastasis, at 12 years postoperatively.

Purpose Stability in the sagittal plane, particularly regarding anterior cruciate ligament compensation, and postoperative functionality and satisfaction remain issues in total knee arthroplasty. Therefore, this prospective study compared the clinical outcomes between medial-pivot-based and posterior-stabilised total knee arthroplasty based on anterior translation and clinical scores. Methods To assess outcomes of total knee arthroplasty for varus osteoarthritis, the anterior translation distance of the tibia relative to the femur was measured at 30 and 60° of flexion using a KS measure Arthrometer at 6 months postoperatively. The 2011 Knee Society Score, Forgotten Joint Score, visual analogue scale for pain, and range of motion were assessed at 6 months and 1 year postoperatively. The correlations among each score, anterior translation distance, range of motion, and visual analogue scale score for pain were investigated. Results The medial-pivot and posterior-stabilised groups comprised 70 and 51 patients, respectively. The medial-pivot group exhibited a significantly shorter anterior translation distance at 60° flexion than the posterior-stabilised group. Furthermore, the medial-pivot group achieved significantly better outcomes regarding the visual analogue scale for pain, 2011 Knee Society Score, and Forgotten Joint Score than the posterior-stabilised group. A significant negative correlation was observed between the anterior translation distance and the function score of the 2011 Knee Society Score, whereas a significant positive correlation was found between the anterior translation distance and flexion angle, and between the extension angle and score of the Forgotten Joint Score or 2011 Knee Society Score. Significant negative correlations were also found between the pain visual analogue scale and both the 2011 Knee Society Score and Forgotten Joint Score. Conclusion In total knee arthroplasty for osteoarthritis, the medial-pivot group displayed a shorter anterior translation distance than the posterior-stabilised group at 6 months postoperatively. The visual analogue scale score for pain was also significantly lower in the medial-pivot group than that in the posterior-stabilised group at both 6 months and 1 year postoperatively. Because a correlation was observed between the anterior translation distance and the function score, medial-pivot-based total knee arthroplasty was considered to significantly improve postoperative function compared to posterior-stabilised total knee arthroplasty.

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Background: Although radiographic coxa profunda is considered an indicator of acetabular over-coverage of the femoral head, recent studies do not support this. The morphological characteristics of coxa profunda are not fully elucidated. Therefore, this study aimed to verify the relationship between the pelvic characteristics and coxa profunda. Methods: This retrospective study included the data of women who had undergone unilateral total hip arthroplasty and whose pelvic anteroposterior radiographs revealed normal hip joint morphology on the contralateral side with a distance of ≥2 mm between the ilioischial line and acetabular floor. Five parameters were measured with axial computed tomography at the central hip joint and compared between the coxa profunda (n = 39) and control (n = 34) groups. Parameters included those related to acetabular anteversion and thickness and bony region position representing the ilioischial line. Results: The mean acetabular anteversion angle was 12.5 ± 4° and 22.3 ± 5.6° in the control and coxa profunda groups, respectively. The mean thickness of the acetabular fossa to the medial wall was 7.5 ± 1.7 and 3.9 ± 1.2 mm in the control and coxa profunda groups, respectively. The mean thickness of the acetabular fossa to the medial wall was 7.5 ± 1.7 and 3.9 ± 1.2 mm in the control and coxa profunda groups, respectively. The acetabulum was more anteverted (p < 0.001) and the acetabular bone was thinner (p < 0.001) in the coxa profunda group than in the control group. Additionally, the bony region representing the ilioischial line was located more posterior to the pelvis in the coxa profunda group than in the control group. Conclusion: Our results suggest that in hip radiographs showing no other significant abnormal findings, coxa profunda is related to dysplasia, with anteversion of the acetabulum and lesser anterior coverage than normal. The acetabulum is also thinner than normal in coxa profunda. These findings can be useful for formulating treatment strategies for hip disorders involving coxa profunda since coxa profunda does not indicate over-coverage as conventionally interpreted; rather, coxa profunda indicates dysplasia in the anterior part of the acetabulum.

Background: The ilioischial line can be an important landmark in determining cup offset in two-dimensional preoperative planning for total hip arthroplasty by identifying the bony region showing the ilioischial line on axial computed tomography (CT). This study aimed to validate the hypothesis that the ilioischial line is located in the bony region where the X-ray beamline to the ilioischial line (line α) is tangent to the medial acetabular cortical bone with a maximum overlap in axial CT images.Methods: Equidistance of the following two measures would prove the validity of our hypothesis: (A) distance between the ilioischial line and the metal cup, measured at the level of the hip center on pelvic radiographs, multiplied by 0.9 to correct for the magnification of the radiograph and (B) distance between the metal cup and line α, which is tangent to the medial acetabular wall with maximum overlap, in the axial CT image at the level of the hip joint center. These two distances were measured for 51 hip joints.Results: The average distance A was 4.5±2 mm, and the average distance B was 4.7±2.1 mm. The difference between distances A and B was 0.2±0.2 (range, 0–2.6) mm. In >90% of the cases, the cortical bone area of the inner acetabular wall, indicating the location of the ilioischial line, was located posteriorly.Conclusions: The ilioischial line is located in the bony region where line α intersects with the acetabular medial wall with maximum overlap on axial CT images.

BACKGROUND: The modified Dall approach is a modified anterolateral approach with osteotomy of the anterior part of the greater trochanter. OBJECTIVES: We aimed to evaluate the adequacy of the modified Dall approach by measuring leg length discrepancy and evaluating offset discrepancy using postoperative radiographs. METHODS: Of 103 cases of total hip arthroplasty (THA), 22 patients (mean age, 66.6 ± 12 years) with > 120 flexion angle on the affected hip (mean, 127.2 ± 6.1°), almost normal opposite hip, and low leg-length discrepancy were included. A stem was inserted, and an appropriate ball neck size was selected to ensure hip stability and avoid dislocation during trial reduction. The ball head inserted had a diameter of 26 mm, and the cup position was at the anatomical hip center. RESULTS: The mean preoperative and postoperative leg length discrepancies were 5.8 ± 6.3 and 0.7 ± 3.5 mm, respectively, the mean postoperative offset discrepancy was 0.7 ± 6.6 mm, and no dislocations occurred. DISCUSSION: We have been using the modified Dall approach for several years. It has yielded minimal leg length discrepancy after THA, with preservation of soft tissue tension. To date, there have been no reports on this procedure, and our results show that it offers maximal stability and minimal leg length discrepancy.