Patients with primary hip osteoarthritis and to determine whether the orientation of their native hip joints corresponded with established recommendations for implantation of prosthetic components. Methods: We retrospectively evaluated a consecutive series of 131 preoperative computed tomography (CT) scans of patients with primary end-stage hip osteoarthritis (fifty-seven male and seventy-four female patients; mean age, sixty years). Patients were positioned according to a standardized protocol. Accounting for pelvic tilt, three-dimensional acetabular orientation was determined in the anatomical reference frame. Moreover, three-dimensional femoral version was measured. Differences in native anatomy between male and female patients were assessed with use of nonparametric tests. Native anatomy was evaluated with reference to the “safe zone” as described by Lewinnek et al. and to a “safe” combined anteversion of 20° to 40°. Results: In the entire cohort, the mean femoral anteversion was 13° and the mean acetabular anteversion was 19°. No significant differences in femoral, acetabular, or combined (femoral and acetabular) anteversion were observed between male and female patients. The mean acetabular inclination was 62°. There was no significant difference in acetabular inclination between female and male patients. We did not observe a correlation among acetabular inclination, acetabular anteversion, and femoral anteversion. Ninety-five percent (125) of the native acetabula were classified as being within the safe anteversion zone, whereas only 15% (nineteen) were classified as being within the safe inclination zone. Combined anteversion was within the safe limits in 63% (eighty-three) of the patients. However, only 8% (ten) of the cases in the present cohort met the criteria of both “safe zone” definitions (that of Lewinnek et al. and combined anteversion). Conclusions: Acetabular anteversion of the osteoarthritic hip as defined by the native acetabular rim typically matches the recommended component “targets” for cup insertion. There was no specific relationship among native acetabular inclination, acetabular anteversion, and femoral anteversion. Neither native acetabular inclination nor native combined anteversion appears to be related to current implant insertion targets. Clinical Relevance: The present findings of native acetabular and femoral orientation in patients with primary hip osteoarthritis support intraoperative component positioning for total hip arthroplasty....

The aim of this retrospective cohort study was to identify any difference in femoral offset as measured on pre-operative anteroposterior (AP) radiographs of the pelvis, AP radiographs of the hip and corresponding CT scans in a consecutive series of 100 patients with primary end-stage osteoarthritis of the hip (43 men and 57 women with a mean age of 61 years (45 to 74) and a mean body mass index of 28 kg/m²(20 to 45)).Patients were positioned according to a standardised protocol to achieve reproducible projection and all images were calibrated. Inter- and intra-observer reliability was evaluated and agreement between methods was assessed using Bland-Altman plots.In the entire cohort, the mean femoral offset was 39.0 mm (95% confidence interval (CI) 37.4 to 40.6) on radiographs of the pelvis, 44.0 mm (95% CI 42.4 to 45.6) on radiographs of the hip and 44.7 mm (95% CI 43.5 to 45.9) on CT scans. AP radiographs of the pelvis underestimated femoral offset by 13% when compared with CT (p < 0.001). No difference in mean femoral offset was seen between AP radiographs of the hip and CT (p = 0.191).Our results suggest that femoral offset is significantly underestimated on AP radiographs of the pelvis but can be reliably and accurately assessed on AP radiographs of the hip in patients with primary end-stage hip osteoarthritis.We, therefore, recommend that additional AP radiographs of the hip are obtained routinely for the pre-operative assessment of femoral offset when templating before total hip replacement.

Background: The presence of hip osteoarthritis is associated with abnormal spinopelvic characteristics. This study aimed to determine whether the preoperative, pathological spinopelvic characteristics normalize at 1 year after total hip arthroplasty (THA). Methods: This was a prospective, longitudinal, case-control, matched cohort study. Forty-seven patients undergoing THA underwent preoperative and 1-year postoperative assessments. This group was matched with regard to age, sex, and body mass index with 47 controls (volunteers) with well-functioning hips. All participants underwent clinical and radiographic assessments including lateral radiographs in standing, relaxed-seated, and deep-flexed-seated positions. Spinopelvic characteristics included change in lumbar lordosis (ΔLL), change in pelvic tilt (ΔPT), and hip flexion (change in pelvic-femoral angle, ΔPFA) when moving from a standing position to either of the seated positions. Spinopelvic hypermobility was defined as ΔPT > 30° between the standing and upright-seated positions. Results: Patients who underwent THA, compared with the control group, preoperatively demonstrated less mean change in hip flexion (ΔPFA, −54.8° ± 17.1° compared with −68.5° ± 9.5°; p < 0.001), greater mean change in pelvic tilt (ΔPT, 22.0° ± 13.5° compared with 12.7° ± 8.1°; p < 0.001), and greater mean lumbar movement (ΔLL, −22.7° ± 15.5° compared with −15.4° ± 10.9°; p = 0.015) transitioning from a standing position to an upright-seated position. After THA, these differences were no longer present between the THA group and the control group: the mean postoperative changes were −65.8° ± 12.5° (p = 0.256) for ΔPFA, 14.3° ± 9.5° (p = 0.429) for ΔPT, and −15.3° ± 10.6° (p = 0.966) for ΔLL. The higher prevalence of spinopelvic hypermobility in the THA group compared with the control group that was observed preoperatively (21% compared with 0%; p = 0.009) was no longer present after THA (6% compared with 0%; p = 0.194). Similar results were found moving from a standing position to a deep-seated position after THA. Conclusions: Preoperative spinopelvic characteristics that contribute to abnormal mechanics can normalize after THA following improvement in hip flexion. This leads to patients having the expected hip, pelvic, and spinal flexion as demographically matched controls, thus potentially eliminating abnormal mechanics that contribute to the development or exacerbation of hip-spine syndrome. Level of Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Background: The aims of this matched cohort study were to (1) assess differences in spinopelvic characteristics between patients who sustained a dislocation after total hip arthroplasty (THA) and a control group without a dislocation, (2) identify spinopelvic characteristics associated with the risk of dislocation, and (3) propose an algorithm including individual spinopelvic characteristics to define an optimized cup orientation target to minimize dislocation risk. Methods: Fifty patients with a history of THA dislocation (29 posterior and 21 anterior dislocations) were matched for age, sex, body mass index (BMI), index diagnosis, surgical approach, and femoral head size with 200 controls. All patients underwent detailed quasi-static radiographic evaluations of the coronal (offset, center of rotation, and cup inclination/anteversion) and sagittal (pelvic tilt [PT], sacral slope [SS], pelvic incidence [PI], lumbar lordosis [LL], pelvic-femoral angle [PFA], and cup anteinclination [AI]) reconstructions. The spinopelvic balance (PI − LL), combined sagittal index (CSI = PFA + cup AI), and Hip-User Index were determined. Parameters were compared between the control and dislocation groups (2-group analysis) and between the controls and 2 dislocation groups identified according to the direction of the dislocation (3-group analysis). Important thresholds were determined from receiver operating characteristic (ROC) curve analyses and the mean values of the control group; thresholds were expanded incrementally in conjunction with running-hypothesis tests. Results: There were no coronal differences, other than cup anteversion, between groups. However, most sagittal parameters (LL, PT, CSI, PI − LL, and Hip-User Index) differed significantly. The 3 strongest predictors of instability were PI – LL >10° (sensitivity of 70% and specificity of 65% for instability regardless of direction), CSI_standing of 244° (anterior instability). A CSI that was not between 205° and 245° on the standing radiograph (CSI_standing) was associated with a significantly increased dislocation risk (odds ratio [OR]: 4.2; 95% confidence interval [CI]: 2.2 to 8.2; p < 0.001). In patients with an unbalanced and/or rigid lumbar spine, a CSI_standing that was not 215° to 235° was associated with a significantly increased dislocation risk (OR: 5.1; 95% CI: 1.8 to 14.9; p = 0.001). Conclusions: Spinopelvic imbalance (PI − LL >10°) determined from a preoperative standing lateral spinopelvic radiograph can be a useful screening tool, alerting surgeons that a patient is at increased dislocation risk. Measurement of the PFA preoperatively provides valuable information to determine the optimum cup orientation to aim for a CSI_standing of 205° to 245°, which is associated with a reduced dislocation risk. For patients at increased dislocation risk due to spinopelvic imbalance (PI − LL >10°), the range for the optimum CSI is narrower. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Sufficient data on outcome of patients with clinically and radiologically aggressive enchondromas and atypical cartilaginous tumors (ACT) is lacking. We therefore analyzed both conservatively and surgically treated patients with lesions, which were not distinguishable between benign enchondroma and low-grade malignant ACT based upon clinical and radiologic appearance. The series included 228 consecutive cases with a follow-up > 24 months to assess radiological, histological, and clinical outcome including recurrences and complications. Pain, satisfaction, functional limitations, and the musculoskeletal tumor society (MSTS) score were evaluated to judge both function and emotional acceptance at final follow-up. Follow-up took place at a mean of 82 (median 75) months. The 228 patients all had comparable clinical and radiological findings. Of these, 153 patients were treated conservatively, while the other 75 patients underwent intralesional curettage. Besides clinical and radiological aggressiveness, most lesions were histologically judged as benign enchondromas. 9 cases were determined to be ACT, while the remaining 7 cases had indeterminate histology. After surgery, three patients developed a recurrence, and a further seven had complications of which six were related to osteosynthesis. Both groups had excellent and almost equal MSTS scores of 96 and 97%, respectively, but significantly less functional limitations were found in the non-surgery group. Further sub-analyses were performed to reduce selection bias. Sub-analysis of histologically diagnosed enchondromas in the surgery group found more pain, less function, and worse MSTS score compared to the non-surgery group. Sub-analysis of smaller lesions (< 4.4 cm) did not show significant differences. In contrast, larger lesions displayed significantly worse results after surgery compared to conservative treatment (enchondromas > 4.4 cm: MSTS score: 94.0% versus 97.3%, p = 0.007; pain 2.3 versus 0.8, p = 0.001). The majority of lesions treated surgically was filled with polymethylmethacrylate bone-cement, while the remainder was filled with cancellous-bone, without significant difference in clinical outcome. Feasibility of intralesional curettage strategies for symptomatic benign to low-grade malignant chondrogenic tumors was supported. Surgery, however, did not prove superior compared to conservative clinical and radiological observation. Due to the low risk of transformation into higher-grade tumors and better functional results, more lesions might just be observed if continuous follow-up is assured.

We assessed the variation in proximal femoral canal shape and its association with geometric and demographic parameters in primary hip OA. In a retrospective cohort study, the joint geometry of the proximal femur was evaluated on radiographs and corresponding CT scans of 345 consecutive patients with end‐stage hip OA. Active shape modeling (ASM) was performed to assess the variation in endosteal shape of the proximal femur. To identify natural groupings of patients, hierarchical cluster analysis of the shape modes was used. ASM identified 10 independent shape modes accounting for >96% of the variation in proximal femoral canal shape within the dataset. Cluster analysis revealed 10 specific shape clusters. Significant differences in geometric and demographic parameters between the clusters were observed. ASM and subsequent cluster analysis have the potential to identify specific morphological patterns of the proximal femur despite the variability in proximal femoral anatomy. The study identified patterns of proximal femoral canal shape in hip OA that allow a comprehensive classification of variation in shape and its association with joint geometry. Our data may improve future stem designs that will optimize stem fit and simultaneously allow individual restoration of hip biomechanics. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:413–422, 2014.