Acetabular cup position differs in spinopelvic mobility types: a prospective observational study of primary total hip arthroplasty patients

Introduction Spinopelvic mobility was identified as a contributing factor for total hip arthroplasty (THA) instability. The influence of spinopelvic function on acetabular cup positioning has not yet been sufficiently investigated in a prospective setting. Therefore, our study aimed (1) to assess cup inclination and anteversion in standing and sitting based on spinopelvic mobility, (2) to identify correlations between cup position and spinopelvic function, (3) and to determine the influence of the individual spinal segments, spinal sagittal balance, and spinopelvic characteristics on the mobility groups. Materials and methods A prospective study assessing 197 THA patients was conducted with stereoradiography in standing and sitting position postoperatively. Two independent investigators determined cup anteversion and inclination, C7-Sagittal vertical axis, cervical lordosis (CL), thoracic kyphosis (TK), lumbar lordosis (LL), sacral slope, pelvic tilt (PT), anteinclination (AI), and pelvic femoral angle (PFA). Spinopelvic mobility is defined based on ∆PT = PTstanding − PTsitting as ∆PT < 10° stiff, ∆PT ≥ 10–30° normal, and ∆PT > 30° hypermobile. Pearson coefficient represented correlations between the cup position and spinopelvic parameters. Results Significant differences were demonstrated for cup anteversion (stiff/hypermobile 29.3°/40.1°; p < 0.000) and inclination (stiff/hypermobile 43.5°/60.2°; p < 0.000) in sitting, but not in standing position. ∆ (standing/sitting) of the cup anteversion (stiff/neutral/hypermobile 5.8°/12.4°/19.9°; p < 0.000) and inclination (stiff/neutral/hypermobile 2.3°/11.2°/18.8°; p < 0.000) revealed significant differences between the mobility groups. The acetabular cup position in sitting, was correlated with lumbar flexibility (∆LL) and spinopelvic mobility. Significant differences were detected between the mobility types and acetabular orientation (AI sit:stiff/hypermobile 47.6°/65.4°; p < 0.000) and hip motion (∆PFA:stiff/hypermobile 65.8°/37.3°; p < 0.000). Assessment of the spinal segments highlighted the role of lumbar flexibility (∆LL:stiff/hypermobile 9.9°/36.2°; p < 0.000) in the spinopelvic complex. Conclusion The significantly different acetabular cup positions in sitting and in the ∆ between standing and sitting and the significantly altered spinopelvic characteristics in terms of stiff and hypermobile spinopelvic mobility underlined the consideration for preoperative functional radiological assessment. Identifying the patients with altered spinopelvic mechanics due to a standardized screening algorithm is necessary to provide safe acetabular cup positioning. The proximal spinal segments appeared not to be involved in the spinopelvic function.

Direct Anterior Versus Anterolateral and Posterolateral Approaches to Total Hip Replacement: Comparative Accuracy of Acetabular Implant Placement and Early Clinical Outcomes

BackgroundDifferent surgical approaches used in total hip arthroplasty (THA) include direct anterior approach (DAA), anterolateral approach (AL), and posterolateral approach (PL). However, the acetabular cup position varies according to surgical view, surgical table, and patient position for each approach. This study is aimed to compare acetabular cup position in THA under different approaches, including surgical time, blood loss, and postoperative complications.MethodsBetween Jan 2017 and Dec 2018, 231 patients who underwent THA (64 DAA, 96 AL, and 71 PL THAs) were analyzed retrospectively. Intraoperative blood loss, operation time, preoperative and postoperative WOMAC score, cup anteversion, inclination angle, and postoperative complications were analyzed.ResultsDAA showed longer operation time and more blood loss, but shorter hospital stays. The cup was found in the safe zone for 97% of DAA patients, 74% of AL patients, and 56% of PL patients. PL showed the highest complication rate (9.9%), followed by DAA (3.1%) and AL (1%). There was no statistically significant difference in preoperative and postoperative WOMAC scores. ConclusionTHA by DAA using a special table is a more reliable procedure to achieve safe cup position. Although DAA showed fewer outliers in cup position, it resulted in longer operation time and greater blood loss compared to other groups.Trial registration: Retrospective study

Severe Leg Length Discrepancy after Total Hip Arthroplasty: Where is the Problem- Cup or Stem? A Retrospective Controlled Study

Background: The factors that contribute to the severe leg length discrepancy (LLD) after total hip arthroplasty (THA) are presently unclear. In the current study, we investigated whether the acetabular cup position and femoral stem are related to the patients with severe LLD by comparing with patients who had the leg length equality.Materials and Methods: Between June 2013 and July 2019, patients undergoing unilateral primary THA in the Department of Orthopaedics at our institution were screened. According to the postoperative leg length difference, a total of 178 patients were included in the study. A group of 107 patients had leg length equality (LLD≤3 mm) and the other group of 71 patients had severe LLD (LLD≥15 mm). A standardized protocol for evaluation of anteroposterior hip radiographs was used to measure the postoperative LLD. The difference of acetabular cup position (vertical centre of rotation (VCR), horizontal centre of rotation (HCR)) and the femoral stem(stem height; stem size; femoral neck osteotomy level) between the two groups. We also assessed whether there was a difference in proximal femur morphology between the two groups.Results: On the femoral side, the mean stem height of (70.82±5.49) mm in the severe LLD group was significantly different from the (67.35±6.88) mm mean discrepancy in the leg length equality group (P < .001). Stem size and femoral neck osteotomy level showed no statistically differences between the two groups (P>0.05). On the acetabular side, there was no significant difference between the two groups in the VCR and HCR (P>0.05) . There was also no statistical difference in proximal femur morphology between the two groups (P>0.05).Conclusion: The main reason for the occurrence of severe LLD may be due to improper treatment of the femur side. Although preoperative template could choose a better stem size and femoral neck osteotomy level, surgeons need to pay more attention to the whole operation process of the femur stem.

Direct Anterior Versus Anterolateral and Posterior Approaches to Total Hip Replacement: Comparative Accuracy of Acetabular Implant Placement and Early Clinical Outcomes

BackgroundDifferent surgical approaches used in total hip arthroplasty (THA) include a direct anterior approach (DAA), anterolateral approach (AL), and posterolateral approach (PL). However, the acetabular cup position varies according to surgical view, surgical table, and patient position for each approach. This study is aimed to compare acetabular cup position in THA under different approaches, including surgical time, blood loss, and postoperative complications.MethodsBetween Jan 2017 and Dec 2018, 231 patients who underwent THA (64 DAA, 96 AL, and 71 PL THAs) were analyzed retrospectively. Intraoperative blood loss, operation time, preoperative and postoperative WOMAC score, cup anteversion, inclination angle, and postoperative complications were analyzed.ResultsDAA showed longer operation time and more blood loss, but shorter hospital stays. The cup was found in the safe zone for 97% of DAA patients, 74% of AL patients, and 56% of PL patients. PL showed the highest complication rate (9.9%), followed by DAA (3.1%) and AL (1%). There was no statistically significant difference in preoperative and postoperative WOMAC scores. ConclusionTHA by DAA using a special table is a more reliable procedure to achieve safe cup position. Although DAA showed fewer outliers in cup position, it resulted in longer operation time and greater blood loss compared to other groups.Trial registration: Retrospective study

Are single plane intraoperative and biplanar postoperative radiographic measurements of acetabular cup position the same?

Purpose: Supine positioning and the use of fluoroscopy during direct anterior approach total hip arthroplasty (DAA THA) have been reported to improve acetabular component positioning. This study aims to compare 2-dimensional intraoperative radiographic RadLink measurements of acetabular component position with 3-dimensional postoperative 3D SterEOS measurements. Methods: Intraoperative fluoroscopy and RadLink (El Segundo, CA, USA) were used to measure acetabular cup position intraoperatively in 48 consecutive patients undergoing DAA THA. Cup position was measured on 6-week postoperative standing EOS images using 3D SterEOS software (EOS Imaging, SA, Paris, France) and compared to RadLink findings using Student’s t-test. Safe-zone outliers were identified. We evaluated for measurement difference of > +/– 5°. Results: RadLink acetabular cup abduction measurement (mean 43.0°) was not significantly different than 3D SterEOS in the anatomic plane (mean 42.6°, p = 0.50) or in the functional plane (mean 42.7°, p = 0.61). RadLink acetabular cup anteversion measurement (mean 17.9°) was significantly different than 3D SterEOS in both the anatomic plane (mean 20.6°, p = 0.022) and the functional plane (mean 21.2°, p = 0.002). RadLink identified 2 cups outside of the safe-zone. However, SterEOS identified 12 (anatomic plane) and 10 (functional plane) outside of the safe-zone. In the functional plane, 58% of anteversion and 92% of abduction RadLink measurements were within +/– 5° of 3D SterEOS. Conclusions: Intraoperative fluoroscopic RadLink acetabular anteversion measurements are significantly different than 3D SterEOS measurements, while abduction measurements are similar. Significantly more acetabular cups were noted to be outside of the safe-zone when evaluated with 3D SterEOS versus RadLink.