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Purpose: Patient-perceived leg length discrepancy (PLLD) is one of the major postoperative complications of total hip arthroplasty (THA). This study aimed to identify factors that cause PLLD following THA., Materials and Methods: This retrospective study included a series of consecutive patients who underwent unilateral THA between 2015 and 2020. Ninety-five patients who underwent unilateral THA with postoperative radiographic leg length discrepancy (RLLD) ≤1 cm were classified into two groups according to the direction of preoperative pelvic obliquity (PO). Standing radiographs of the hip joint and whole spine were obtained before and one year after THA. The clinical outcomes and the presence or absence of PLLD was confirmed one year after THA., Results: Sixty-nine patients were classified as having type 1 PO (rising toward the unaffected side) and 26 were classified as having type 2 PO (rising toward the affected side). Eight patients with type 1 PO and seven with type 2 PO had PLLD postoperatively. In the type 1 group, patients with PLLD had larger preoperative and postoperative PO values and larger preoperative and postoperative RLLD than those without PLLD (p = 0.01, p < 0.001, p = 0.01, and p = 0.007, respectively). In the type 2 group, patients with PLLD had larger preoperative RLLD, larger amount of leg correction, and a larger preoperative L1-L5 angle than those without PLLD (p = 0.03, p = 0.03, and p = 0.03, respectively). In type 1, postoperative PO was significantly associated with postoperative PLLD (p = 0.005), but spinal alignment was not an indicator of postoperative PLLD. The area under the curve (AUC) for postoperative PO was 0.883 (good accuracy) with a cut-off value was 1.90° CONCLUSION: Rigidity of the lumbar spine might lead to postoperative PO as a compensatory movement, resulting in PLLD after THA in type 1. Further research on the relationship between flexibility of the lumbar spine and PLLD is needed., (Copyright © 2023 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: This study evaluated the accuracy of the cup alignment angles and spatial cup positioning on computed tomography (CT) images in patients with osteoarthritis secondary to developmental dysplasia of the hip (DDH) who underwent total hip arthroplasty (THA) using a minimally invasive technique via an anterolateral approach in the supine position according to whether a robotic arm-assisted system or a CT-based navigation system was used., Methods: We reviewed 60 robotic arm-assisted (RA)-THA cases and 174 navigation-assisted (NA)-THA cases. After propensity score matching, there were 52 hips in each group. Postoperative cup alignment angles and position were assessed by superimposition of a three-dimensional cup template onto the actual implanted cup using postoperative CT images with pelvic coordinates matching the preoperative planning., Results: The mean absolute error of the inclination angle and the anteversion angle between the preoperative planning and the postoperative measurement was significantly smaller in the RA-THA group (inclination, 1.1° ± 0.9; anteversion, 1.3° ± 1.0) than in the NA-THA group (inclination, 2.2° ± 1.5; anteversion, 3.3° ± 2.5). For acetabular cup positioning, the mean discrepancy between the preoperative planning and the postoperative measurement was 1.3 ± 1.3 mm on the transverse axis, 2.0 ± 2.0 mm on the longitudinal axis, and 1.3 ± 1.7 mm on the sagittal axis in the RA-THA group and 1.6 ± 1.4 mm, 2.6 ± 2.3 mm, and 1.8 ± 1.3 mm, respectively, in the NA-THA group. High precision of cup positioning was observed in both groups with no statistically significant difference., Conclusion: Robotic arm-assisted THA using a minimally invasive technique via an anterolateral approach in the supine position allows accurate cup placement in patients with DDH., (Copyright © 2023 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Full-endoscopic (FE) lumbar interbody fusion (LIF) is now a widely used type of minimally invasive surgery (MIS). Although FE-LIF includes LIF with foraminoplasty via a Kambin's triangle approach (FE-KLIF) and LIF with foraminotomy via an interlaminar approach, these techniques are rarely discussed separately. This review evaluates the outcomes and complications of FE-KLIF reported in the literature. The PubMed, Medline, Embase, Web of Science, and Cochrane Library databases were searched for studies reporting the outcomes of FE-KLIF. Of 464 publications assessed, 11 met our inclusion criteria. Although the most frequently treated level was L4/5, L5/S1 was also treated. FE-KLIF was performed under local anesthesia and sedation or under epidural anesthesia without general anesthesia. Visual analog scale and Oswestry Disability Index scores were improved postoperatively in all uncontrolled studies; however, there was no significant difference in these scores in studies that compared FE-KLIF with posterior LIF (PLIF) or MIS-transforaminal LIF (TLIF). There was also no significant difference in the fusion rate between FE-KLIF and PLIF or MIS-TLIF. In terms of complications, although there were no reports of hematoma, dural tear and surgical site infection were reported in 1 paper each, with transient nerve disorders reported in 5 studies (frequency, 1.8%-23.5%). This review indicates that FE-KLIF is a feasible and viable surgical option for lumbar degenerative disease. However, the amount and level of evidence is low for the studies included in this review, and the data on long-term outcomes remain limited., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Although bicruciate stabilized total knee arthroplasty (BCS-TKA) is expected to provide kinematics similar to those of the normal knee, there are limited data available for comparison of the kinematics of the knee after BCS-TKA with those of the normal knee. The purpose of this study was to confirm whether the knee after BCS-TKA are the same as those of the native knee., Methods: Seven fresh-frozen cadavers underwent TKA using a BCS-type prosthesis with navigation system. Anteroposterior translation of the femur and internal rotation of the tibia were evaluated using the navigation system., Results: There was no statistically significant difference in anteroposterior translation of the femur between the native knee and the knee after BCS-TKA in the early flexion phase (0°-30°) or in the deep flexion phase (over 100°). In the middle flexion phase (40°-90°), the knee after BCS-TKA was placed significantly more anteriorly than the native knee. The knee after BCS-TKA also showed a gradual internal rotation pattern similar to that of the native knee but the total tibial internal rotation angle was significantly smaller than that of the native knee. At each angle from 0° to 120° of flexion, internal rotation of the knee after BCS-TKA was significantly greater than that of the native knee., Conclusion: Kinematics of BCS-TKA is close to that of the native knee. However, there is a statistically significant difference in AP position of the femur during mid flexion and initial rotational position of the tibia between the BCS-TKA knee and the native knee., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Soft tissue balance is an important determinant of the outcome of total knee arthroplasty (TKA). However, there are differences in the joint gap and ligament balance between the osteotomized femoral and tibial surfaces and those after TKA. The aim of this study was to compare the relationship between the femur and tibia at insertion of a spacer block with that after cruciate-retaining (CR) TKA., Methods: Thirty knees in 30 patients (26 women, 4 men) who underwent primary CR TKA with a navigation system were enrolled. Mean age at surgery was 76.3 (range, 63-87) years. After osteotomy of the femur and tibia, the flexion-extension gap and ligament balance were evaluated using a spacer block. The location of the tibial center in relation to the femoral center in the sagittal plane calculated from navigation data at insertion of an appropriately sized spacer block in knee flexion was compared with that after CR TKA using the paired t-test., Results: The mean sagittal location of the tibial center relative to the femoral center in knee flexion was 5.16 (range, -2.4, 16.3) mm at insertion of the spacer block and 6.60 (range, -1.4, 15.1) mm after CR TKA, and this difference was significant (p = 0.016)., Conclusion: Assessment of soft tissue balance using a spacer block in CR TKA during knee flexion changes the location of the tibia. Surgeons should be aware of the potential for overestimating the postoperative flexion gap in CR TKA when using a spacer block to assess the flexion gap., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: A highly porous titanium cup has a unique structure that mimics human trabecular bone and is expected to achieve better outcomes due to rigid fixation and extensive bone ingrowth. Several manufacturers have developed a highly porous titanium cup; however, some have shown a high incidence of radiolucent lines (RLLs) on early postoperative radiographs. In this study, we compared the clinical and radiological outcomes of total hip arthroplasty (THA) using a highly porous titanium cup (OsseoTi, Zimmer Biomet) with those after THA using a conventional hydroxyapatite-coated titanium cup (Trident HA, Stryker)., Methods: A total of 201 hips that underwent THA using an OsseoTi cup (n = 101) or Trident cup (n = 100) were enrolled in the study. Patient characteristics, cup alignment, clinical outcome (determined by the Japanese Orthopedic Association [JOA] score), and incidence of RLLs around the cup were evaluated at 3, 6, 12, and 24 months postoperatively., Results: The clinical outcome was excellent in both groups. The incidence of RLLs was 12.9% at 3 months, 20.8% at 6 months, 23.8% at 12 months, and 22.8% at 24 months after surgery in the OsseoTi group; there were no cases of RLL at any time after surgery in the Trident group. The RLLs were mainly distributed in zone 2. Despite the high rate of RLL in the OsseoTi group, the RLL were narrow and only 5% had a width of >1 mm at 24 months postoperatively. There were no cases with RLLs in all three zones., Conclusions: Despite excellent clinical outcomes in both study groups, the incidence of RLLs was higher in the OsseoTi group than in the Trident group. Although none of our cases with RLL have required revision surgery for aseptic loosening so far, these patients require careful follow-up., Competing Interests: Declaration of competing interest None declared., (Copyright © 2020. Published by Elsevier B.V.)

Introduction: Intertrochanteric fractures are common fragility fractures in elderly patients. The importance of a reliable classification system for these fractures has been increasingly recognized. The aim of this study was to test the hypothesis that three-dimensional classification by CT has better intra- and inter-observer reliability than conventional two-dimensional classification., Material and Methods: Two hundred and three consecutive patients (39 male, 164 female; mean age 84.5 years) with intertrochanteric fracture were included in the study. In each case, the fracture was classified using the two-dimensional Evans-Jensen and AO/OTA systems that rely on plain radiographs and using a three-dimensional fragment-based CT system. The second evaluation was performed 1 month after the first evaluation by the same examiner to determine intra-observer reliability. Another blinded examiner also classified each case to assess inter-observer reliability. The kappa coefficient was used for determination of intra- and inter-observer reliability., Results: The kappa values for the two-dimensional Evans-Jensen and AO/OTA classification systems showed moderate intra-observer reliability (κ=0.65 and κ=0.61, respectively) and slight inter-observer reliability (κ=0.20 and κ=0.19). The intra-observer kappa value for the three-dimensional classification system was 0.88, indicating almost perfect reliability; the inter-observer kappa value was 0.70, indicating substantial reliability., Conclusion: The findings of this study confirm that the fragment-based classification system has high reliability. Surgeons should be aware that the three-dimensional fragment-based CT system for classification of intertrochanteric fractures has better intra-observer and inter-observer reliability than the conventional two-dimensional systems., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Coxa profunda is generally considered an indicator of acetabular overcoverage. However, recent studies have opposed this view. The correlation between coxa profunda and acetabular overcoverage thus remains controversial. The purpose of this study was to investigate the prevalence of coxa profunda and the association between coxa profunda and acetabular coverage based on sex in Japanese subjects using computed tomography., Methods: We reviewed the computed tomography scans of 151 Japanese consecutive patients (302 hips) aged <50 years who underwent abdominopelvic computed tomography for symptoms unrelated to hip disease. Coxa profunda was diagnosed when the floor of the acetabular fossa touched or was medial to the ilioischial line. We measured the lateral center edge angle, acetabular roof obliquity angle, acetabular version, and anterior and posterior acetabular sector angles as parameters of acetabular coverage., Results: Coxa profunda was observed in 45.7% of all subjects, and was more common in females (63.0%) than in males (29.5%). We found no significant differences in the incidence of coxa profunda among subjects with dysplasia, overcoverage, and normal coverage. Males with coxa profunda showed significantly greater lateral center edge angle, anterior acetabular sector angle, and lower acetabular roof obliquity angle, whereas anterior and posterior acetabular sector angles were greater in all subjects and females with coxa profunda. Coxa profunda showed poor sensitivity (57.7%) and specificity (56.8%) for detecting overcoverage in all subjects., Conclusions: Coxa profunda is a common radiographic feature in Japanese patients, especially in women. Coxa profunda may be less useful for diagnosing acetabular overcoverage because of its common occurrence with various hip morphologies and its poor specificity for detecting acetabular overcoverage. However, men with coxa profunda have greater acetabular coverage, so coxa profunda may contribute to acetabular coverage in men. We should take into account that coxa profunda may have different implications between the sexes., (Copyright © 2016 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)