Morphological features of the acetabulum with coxa profunda in women: a retrospective observational study.

BACKGROUND: The morphology of coxa profunda remains inadequately understood. However, knowledge about the characteristics of the acetabulum in coxa profunda can help to predict pelvic morphology in three dimensions based on radiographic findings, as well as help to diagnose and predict hip pathologies. Therefore, this study aimed to investigate the relationship between the morphological characteristics of the pelvis and coxa profunda. METHODS: We conducted a retrospective analysis including women who had undergone unilateral total hip arthroplasty. Only those with normal hip joint morphology on the opposite side, as evidenced by anteroposterior pelvic radiography showing a distance of ≥ 2 mm between the ilioischial line and acetabular floor, were included. Five parameters related to acetabular anteversion, thickness, and the position of the ilioischial line were measured using axial computed tomography at the central hip joint. The coxa profunda group (n = 39) and control group (n = 34) were compared. RESULTS: The mean acetabular anteversion angle was 12.5° ± 4° in the control group and 22.3° ± 5.6° in the coxa profunda group. The mean thickness from the acetabular fossa to the medial wall was 7.5 ± 1.7 mm in the control group and 3.9 ± 1.2 mm in the coxa profunda group. Furthermore, the bony region representing the ilioischial line was positioned more posteriorly in the coxa profunda group than it was in the control group. CONCLUSION: Our findings suggest that coxa profunda in women is associated with anterior acetabular dysplasia and a thin acetabulum, in contrast to previous interpretations of excessive coverage. This insight suggests a conversion of coxa profunda from a finding of pincer-type femoroacetabular impingement to a finding of acetabular dysplasia, a revelation that also draws attention to cup positioning for total hip arthroplasty.

Measurement of the normal contralateral hip flexion angle and posterior pelvic tilt angle using a pelvic guide pin in total hip arthroplasty.

BACKGROUND: We aimed to measure the posterior pelvic tilt angle at maximum hip flexion and hip flexion range of motion at the femoroacetabular joint using a pelvic guide pin and to examine the difference in flexion range of motion when determined by a physical therapist and under anesthesia. METHODS: Data of 83 consecutive patients undergoing primary unilateral total hip arthroplasty were assessed. Using a pin inserted into the iliac crest to define the cup placement angle under anesthesia before and after total hip arthroplasty, the posterior pelvic tilt angle was determined as the change in pin tilt from the supine position to maximum hip flexion. Flexion range of motion under anesthesia was calculated as the difference in the angle between the trunk and thigh at maximum flexion and the posterior pelvic tilt angle. Flexion range of motion with a fixed pelvis measured preoperatively by a physical therapist was compared to that under anesthesia. A goniometer was used for all measurements and the number of measurements was one. FINDINGS: Mean posterior pelvic tilt angle of the pin inserted into the pelvis under anesthesia was 15.8° ± 5.3° (3°-26°) preoperatively and 12.1° ± 4.9° (3°-26°) postoperatively. Mean flexion range of motion under anesthesia was 109.4° ± 6.9° (88°-126°) and that measured by a physical therapist was 101.1° ± 8.2° (80°-120°); the difference was significant (9.7°; p < 0.01). INTERPRETATION: These results highlight the difficulty in accurately determining hip flexion angles without the use of special devices and may help surgeons and physical therapists recognize and address this issue.

Comparison of weight-bearing full-length radiography and three-dimensional computed tomography scan-based models to assess knee joint coronal alignment following total knee arthroplasty.

BACKGROUND: The validity of standing long-leg radiography (LLR) - the standard method for evaluating coronal alignment after total knee arthroplasty (TKA) - remains controversial. We evaluated the measurement reliability and validity of LLR following TKA by comparing postoperative radiographs with three-dimensional computed tomography (3DCT) scans of the lower extremities. METHODS: We retrospectively collected the data of 55 knees from 44 patients who underwent postoperative 3DCT and 5-day and 6-month LLR for coronal alignment evaluation following TKA. The coronal femoral component angle (CFA) and coronal tibial component angle (CTA) were measured using 3DCT and LLR images. Correlations between the hip-knee-ankle angle (HKAA), CFA and CTA were analysed using Pearson's correlation coefficient (PCC); Bland-Altman plots were constructed to assess agreement between 5-day and 6-month radiographic and 3DCT scan measurements. RESULTS: The mean difference in HKAA between 3DCT, and 5-day and 6-month LLR was 1.3 ± 1° and 1.1 ± 0.7°, respectively. Differences of >1° in HKAA between 3DCT, and 5-day and 6-month LLR were observed in 31 (56.4%) and 28 (50.9%) knees, respectively; differences of >2° in these parameters were observed in 15 (27.3%) and nine (16.4%) knees, respectively. The 3DCT scan and radiograph measurements of HKAA, CFA and CTA were strongly correlated (PCC, 0.81-0.92; P < 0.001). Bland-Altman plot validity was within acceptable limits. CONCLUSION: LLR shows good reliability and validity for measuring coronal alignment. When comparing 3DCT scans and radiographs, a high number of HKAA values differed by more than 1° and 2°; this indicates that rigorous alignment evaluation requires 3DCT measurements.

Medial pivot-based total knee arthroplasty achieves better clinical outcomes than posterior-stabilised total knee arthroplasty.

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.

Localization of the ilioischial line on axial computed tomography images for preoperative planning of total hip arthroplasty.

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.

Calcaneal insufficiency fractures following ipsilateral total knee arthroplasty.

INTRODUCTION: Only a few reports have described calcaneal insufficiency fractures (IFs) following total knee arthroplasty (TKA). Herein, we describe nine cases of calcaneal IFs following ipsilateral TKA. The purpose of this study was to investigate the incidence of calcaneal fractures following TKA and determine the characteristics of patients with IFs. PATIENTS AND METHODS: We retrospectively investigated cases of calcaneal IF that occurred following TKA. We collected and analyzed radiographic and magnetic resonance imaging (MRI) findings as well as patient demographic data. We compared the demographic data, bone mineral density (BMD), and preoperative hip-knee-ankle angle (HKA) between cases with a calcaneal fracture following TKA and 100 cases without a fracture following TKA. RESULTS: We performed a total of 1548 knee arthroplasties at our clinic from 2011 to 2020. Nine calcaneal IFs in eight patients were diagnosed following ipsilateral TKA. All patients were women with varus knee osteoarthritis (mean age, 71.8 years). The average change in the alignment angle was 14.7° ± 5.4°. In eight cases, dysfunction was observed in the opposite lower limb. The postoperative onset of hindfoot pain started at an average of 5.6 months. In seven patients, calcaneal fractures occurred idiopathically, but in one patient, two fractures occurred after long-distance walking. No abnormal findings on a calcaneus radiograph were seen for six fractures. MRI demonstrated a definite fracture line and bone marrow edema in all patients. All patients, except one with type 2 diabetes mellitus (T2DM), had osteoporosis. Fractures healed without complications in eight patients; however, the calcaneal anterior facet fracture became displaced and caused a flat foot in one case. The calcaneal IF rate was 0.58% among all cases. Besides one case with T2DM, significant differences were observed in preoperative HKA and BMD between cases with a calcaneal fracture following TKA and those without a fracture. CONCLUSIONS: A change in the load on the calcaneus due to changes in the alignment of the lower extremities after TKA may cause calcaneal IFs. Orthopedic surgeons should be aware of the possible occurrence of calcaneal IFs following TKA, especially in women with osteoporosis and severe varus knee.