Impact of acetabular roof's angle on precision of cup center of rotation reproduction and placement in total hip arthroplasty.

Introduction: Total hip arthroplasty (THA) is nowadays considered as the most effective treatment option for end-stage hip osteoarthritis (OA) and one of the most successful orthopedic procedures. Precise reproduction of the center of rotation (COR) is among the most important aspects of recreating native hip biomechanics after THA as it is strictly related to muscle tension and force distribution within the hip joint. Both vertical and horizontal shift in cup positioning and COR restoration are commonly observed radiological signs corresponding with lesser functional outcome. The aim of this study was to assess whether the superior border of the native acetabulum morphology has an impact on cup positioning and COR restoration in patients undergoing THA as treatment of primary OA of the hip. Material and methods: A cohort of 150 consecutive patients with diagnosis of end-stage primary hip OA who underwent THA via an anterolateral approach with the same implant in 2021 was analyzed retrospectively. Standard standing pelvic X-rays were performed pre- and postoperatively and appropriate measurements were taken. Several radiological parameters on obtained X-rays were assessed. Statistical analysis of all the measurements was performed. Results: There was a statistically significant positive weak correlation between cup offset and acetabular roof angle (rs = 0.25, p = 0.002). There were statistically insignificant positive correlations between acetabular roof angle and COR restoration (rs = 0.14, p = 0.097), acetabular roof angle and total offset (rs = 0.087, p = 0.29) and a negative correlation between acetabular roof angle and femoral offset (rs = 0.071, p = 0.39). Conclusions: The present study revealed that preoperative acetabular roof angle influences the positioning of the prosthetic cup in the transverse axis. There also seems to be a correlation between the acetabular roof angle and COR restoration, but its significance needs further evaluation. Surgeons could use this knowledge to preoperatively assess the risk of cup malposition and adjust their technique during the THA procedure with probable improvement of hip function.

Establishing femoral component rotation using a dynamic tensioner does not improve patellar position after total knee replacement with use of anatomic implants: A case-control study.

BACKGROUND: Anterior knee pain (AKP) is one of the reasons for dissatisfaction after total knee replacement (TKR). It may result from patellofemoral joint dysfunction, caused by improper rotation of implant components. The aim of this study was to analyze patella positioning in patients after standard measured resection TKR and TKR with a use of a dynamic tensioner, and to assess the frequency of AKP, range of motion (ROM), and patient-reported outcome measures 6 weeks and 3 months postoperatively. METHODS: The study consisted of 127 patients who underwent TKR. Eighty-nine of them treated with use of the dynamic tensioner FUZION formed the study group; the remainder formed the control group. All participants received cemented PERSONA MC without patella resurfacing. All patients had a standard anteroposterior, lateral weight-bearing, long-leg view X-ray and computed tomography examination in 30° of knee flexion following the procedure. RESULTS: There were no significant differences between the study and the control groups regarding: posterior condylar axis (PCA)-patella angle, surgical transepicondylar axis (sTEA)-patella angle, PCA-sTEA angle, deviation from 90° in PCA-patella, sTEA-patella and PCA-sTEA angles. No significant difference was found in a ratio of obtaining PCA-patella angle deviation of more than 3°. Regarding clinical parameters, statistically and questionablly clinically significant difference in favor of the Study Group was found in Forgotten Joint Score 6 weeks and 3 months post-operativley and ROM 6 weeks post-operatively. However, such difference was not found by analyzing ROM 3 months post-operatively, AKP and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores. CONCLUSION: Compared with the standard 3° of femoral component external rotation, use of a dynamic tensioner does not allow for more accurate restoration of the patellar facet position with reference to the PCA.

Bone Quality Assessment Before Total Hip Arthroplasty: The Role of Densitometry.

Background Total hip arthroplasty (THA) is effective in the treatment of hip osteoarthritis. Radiographic evaluation, standard in THA planning, is sufficient in examining hip anatomy, although it may not precisely assess bone quality. A routinely implemented method in bone quality assessment is densitometry. The technique allows for a measurement of bone mineral density (BMD). Methodology In the study, we included 26 participants who qualified for THA. All the patients were preoperatively examined with radiographs and densitometry of the affected hip. On the preoperative anteroposterior radiograph, we measured the canal-to-calcar isthmus ratio (CC ratio) and the cortical index (CI). Intraoperatively, during the THA procedure, we measured the thickness of the cortical bone and the diameter of the femoral neck in the line of neck resection. Results The examination with Pearson's correlation coefficient revealed that BMD significantly positively correlates with the intraoperatively measured diameter of the femoral neck (r = 0.5, P = 0.009), and with the measured thickness of the cortical bone (r = 0.47, P = 0.015), CI significantly positively correlates with the intraoperatively measured diameter of the femoral neck (r = 0.6, P = 0.001), and with the CC ratio (r = 0.44, P = 0.024), the intraoperatively measured diameter of the femoral neck significantly positively correlates with the intraoperatively measured thickness of the cortical bone (r = 0.59, P = 0.001). All of the other correlations were not statistically significant. Conclusions BMD measurements can be used in THA planning as they positively correlate with intraoperative measurements. The radiological parameters (CC ratio and CI) may not be as precise in bone quality assessment.

Assessment of the Length of the Pedicle of the Anterolateral Thigh Flap.

Purpose To estimate the length of the pedicle of the anterolateral thigh flap (ALT) and to assess how this length corresponds with the distances between the anatomical landmarks. Methods The study group consisted of patients who underwent computed tomography angiograms ranging minimally from the anterior superior iliac spine (ASIS) superiorly and tibia inferiorly. In the study we included 44 patients. In the axial window we identified single scans with (1) ASIS, (2) the apex of the greater trochanter, (3) the origin of the descending branch of the lateral femoral circumflex artery (LFCA), (4) the superolateral corner of the patella, (5) knee joint gap. Knowing the slice thickness in every patient and the difference in scan number we measured (A)-the distance between the scan (1) and the scan (4). This distance (A) represented the length of the line connecting ASIS and the superolateral corner of the patella (AP line). Next, we identified (6) the midpoint of the distance (A). Next we measured (B)-the distance between the scan (2) and the scan (5) and (C)-the distance between the scan (3) and the midpoint of the AP line (6). Results Mean distances between the scans were: (A) 45.34 cm (SD=4.14), (B) 43.12 cm (SD=4.08), (C) 11.69 cm (SD=1.62). There was low positive correlation between the distance (A) and the distance (C) (rs=0.43) and moderate positive correlation between the distance (B) and the distance (C) (rs=0.53). Conclusion Our study suggests that the mean estimated length of the ALT flap pedicle is 11.69 cm and that it positively correlates with the length of the femur and the length of the AP line.