Sagittal Imbalance Does Not Influence Cup Anteversion in Total Hip Arthroplasty Dislocations

Increased Cup Anteversion May Not Prevent Posterior Dislocation in Patients With Abnormal Spinopelvic Characteristics in Total Hip Arthroplasty

Background

The aims of this study were to (1) assess the degree of variation in acetabular component placement and combined anteversion in a large cohort of dislocating total hip arthroplasties; (2) assess the spinopelvic characteristics of the cohort; and (3) examine the association between cup anteversion and reported direction of instability.

Methods

A commercial database of 245 dislocating total hip arthroplasties referred for postoperative computed tomography and functional radiographic imaging and analysis were reviewed. Spinopelvic parameters and cup and stem positions were measured in the supine, standing, flex-seated, and anterior pelvic plane (APP) positions. Spinopelvic characteristics were stratified by high, neutral, and low cup anteversion using thresholds of >35° and <15° anteversion in standing, respectively.

Results

In the dislocation cohort, 62%, 45%, and 42% of cups were within the safe zone in supine, standing, and the APP, respectively (P < .001). Patients with high vs neutral or low cup anteversion had significantly stiffer spines, more posterior pelvic tilt in standing, greater changes in pelvic tilt, and higher sagittal imbalance. Of the 45 patients with high cup anteversion and reported instability direction, 60% and 40% were reported to have posterior and anterior instability, respectively, with no differences in spinopelvic characteristics.

Conclusions

In this dislocating cohort, there is a decreased percentage of cups within the safe zone in the APP and standing position compared to the supine reference. In addition, we found that patients having poor spinopelvic characteristics and high cup anteversion can still dislocate, suggesting that adjusting cup anteversion alone may not be sufficient for preventing instability.

Risk of Dislocation and Revision Following Primary Total Hip Arthroplasty in Patients With Prior Lumbar Fusion With Spinopelvic Fixation

BACKGROUND

The effect of spinopelvic fixation in addition to lumbar spinal fusion (LSF) on dislocation/instability and revision in patients undergoing primary total hip arthroplasty (THA) has not been reported previously.

METHODS

The PearlDiver Research Program was used to identify patients aged 30 and above undergoing primary THA who received (1) THA only, (2) THA with prior single-level LSF, (3) THA with prior 2-5 level LSF, or (4) THA with prior LSF with spinopelvic fixation. The incidence of THA revision and dislocation/instability was compared through logistic regression and Chi-squared analysis. All regressions were controlled for age, gender, and Elixhauser Comorbidity Index (ECI).

RESULTS

Between 2010 and 2018, 465,558 patients without history of LSF undergoing THA were examined and compared to 180 THA patients with prior spinopelvic fixation, 5,299 with prior single-level LSF, and 1,465 with prior 2-5 level LSF. At 2 years, 7.8% of THA patients with prior spinopelvic fixation, 4.7% of THA patients with prior 2-5 level LSF, 4.2% of THA patients with prior single-level LSF, and 2.2% of THA patients undergoing only THA had a dislocation event or instability (P < .0001). After controlling for length of fusion, pelvic fixation itself was associated with higher independent risk of revision (at 2 years: 2-5 level LSF + spinopelvic fixation: aHR = 3.15, 95% CI 1.77-5.61, P < .0001 vs 2-5 level LSF with no spinopelvic fixation: aOR = 1.39, 95% CI 1.10-1.76, P < .0001).

CONCLUSION

At 2 years, spinopelvic fixation in THA patients were associated with a greater than 3.5-fold increase in hip dislocation risk compared to those without LSF, and an over 2-fold increase in THA revision risk compared to those with LSF without spinopelvic fixation.

LEVEL OF EVIDENCE

III.

Spinopelvic alignment and low back pain after total hip arthroplasty: a scoping review

OBJECTIVE

Spinopelvic alignment is increasingly considered as an essential factor for maintaining an energy-efficient posture in individuals with normal or pathological status. Although several previous studies have shown that changes in the sagittal spinopelvic alignment may occur in patients undergoing total hip arthroplasty (THA), no review of this area has been completed so far. Thus, the objective of this scoping review was to summarize the evidence investigating changes in spinopelvic alignment and low back pain (LBP) following THA.

DATA SOURCES

We adhered to the established methodology for scoping reviews. Four electronic databases were systematically searched from inception-December 31, 2021.

STUDY SELECTION

We selected prospective or retrospective observational or intervention studies that included patients with THA.

DATA EXTRACTION

Data extraction and levels of evidence were independently performed using standardized checklists.

DATA SYNTHESIS

A total of 45 papers were included in this scoping review, involving 5185 participants with THA. Pelvic tilt was the most common parameter measured in the eligible studies (n = 26). The results were not consistent across all studies; however, it was demonstrated that the distribution of pelvic tilt following THA had a range of 25° posterior to 20° anterior. Moreover, decreased sacral slope and lower pelvic incidence were associated with increased risk of dislocation in patients with THA. Lumbar spine scoliosis did not change significantly after THA in patients with bilateral hip osteoarthritis (5.50°(1.16°) vs. 3.73°(1.16°); P-value = 0.29). Finally, one study indicated that LBP improvement was not correlated with postoperative changes in spinopelvic alignment parameters. Several methodological issues were addressed in this study, including no sample size calculation and no type-I error adjustment for outcome multiplicity.

CONCLUSIONS

Changes in spinopelvic alignment may occur after THA and may improve with time. Patients with a THA dislocation usually show abnormal spinopelvic alignment compared to patients without a THA dislocation. LBP usually improves markedly over time following THA.

Surgical correction for adult spinal deformity increases acetabular lateral coverage of femoral heads

BACKGROUND

Studies explaining the relationship between hip and spine reported that spinal corrective surgery affected acetabular orientation and changes in pelvic tilt were capable of influencing radiographic measures of acetabular coverage. This study aimed to assess the change in coronal parameters for acetabular coverage as a result of adult spinal deformity (ASD) correction and to analyze the relationship between the postoperative changes in sagittal spinopelvic parameters and coronal acetabular coverage parameters.

METHODS

Fifty-two consecutive patients who had undergone multilevel spinal surgical correction were enrolled and evaluated. Coronal acetabular coverage parameters included Tönnis angle (TA), lateral center edge angle (LCEA), and the angle of Sharp (SA). All radiographic parameters were evaluated at the preoperative and the postoperative 1 year. Paired t test was used to determine whether there were significant changes between the time points. Bivariate correlation and linear regression analysis were used to assess the relationship between the postoperative changes of spinal alignment and acetabular orientation.

RESULTS

The surgical correction resulted in significant decrease of TA, increase of LCEA and SA, respectively (p < 0.001). The changes in pelvic tilt (PT) demonstrated weak correlation on TA (β = 0.117, p < 0.001 for right; β = 0.111, p < 0.001 for left).

CONCLUSIONS

Although the surgical correction of ASD significantly changed PT resulting in increased acetabular lateral coverage parameters, the correlation between the changes of PT following sagittal correction of ASD and acetabular coverage parameters was low.

TRIAL REGISTRATION

This study was retrospectively registered with approval by the institutional review board (IRB) of our institution (approval number: KHNMC-2020-10-010).

Pelvic incidence affects postoperative dislocation rate in total hip arthropalsty patients with spinal fusion

PURPOSE

The purpose of this study was to compare the clinical outcome of total hip arthroplasty (THA) with and without spinal fusion (SF), and to evaluate the radiographic characteristics of patients with dislocation after THA.

METHODS

A case-controlled study of 53 patients (67 hips) who underwent both THA and SF was performed. The control group was matched to the SF group by age, gender and body mass index, and 106 patients (134 hips) were selected. Hip function was evaluated using the Japanese Orthopaedic Association (JOA) hip score. In addition, the incidence rates of postoperative complications were determined. Radiograph evaluation included lateral inclination and anteversion of the acetabular component. We also analysed sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI).

RESULTS

The JOA hip score at final follow up was significantly poorer in the SF group compared to the control group. There were 5 cases of dislocations in the SF group and none in the control group. The anteversion of acetabular cup, PT, and PI were significantly higher in the SF group compare to the control group. In particular, the PI of patients with anterior dislocation were significantly higher compare to those of patients without dislocation.

CONCLUSIONS

Our study showed that SF is a risk factor for a poorer clinical outcome and postoperative dislocation of THA. In addition, the abnormal value of PI may be a risk factor to predict dislocation after THA with SF.

No linear correlation between pelvic incidence and acetabular orientation: Retrospective observational study

Links between sagittal spinal alignment and acetabular orientation attract considerable research attention with the goal of understanding “hip-spine syndrome.” However, whether pelvic incidence (PI) is related to acetabular orientation remains debatable. The purpose of the present study was to determine: 1. whether the correlation between PI and acetabular orientation is present in pelvises of young healthy adults, and 2. whether the correlation is present in subgroups of sex, or between the left and right pelvis. We analyzed 100 abdominopelvic computed tomography (CT) scans of skeletally healthy young adults. We measured PI and acetabular orientation with three-dimensional (3D) measurements. The orientation of 200 acetabula was measured using 3D reconstructed models of 100 pelvises in the coordinate system based on the anterior pelvic plane (APP). To quantify the acetabular orientation, the radiographic definitions of anteversion and inclination were used. To examine the correlation between acetabular orientation and PI, Pearson's correlation was used. The mean PI was 46.9° ± 10.2°, and the mean acetabular orientation 15.3° ± 5.7° anteverted and 37.5° ± 3.9° inclined. While no significant difference in the PI was observed, the average acetabular orientation of female pelvises (anteversion, 17.5° ± 5.6°; inclination, 36.7° ± 3.7°) was more anteverted and less inclined compared to that of male pelvises (anteversion, 13.2° ± 4.9°; inclination, 38.3° ± 3.9°, respectively; P values < .05). The correlation between PI and acetabular orientation was statistically not significant. After division of study group by sex, the linear correlation between PI and acetabular orientation was not statistically supported. The asymmetry of the acetabular orientation between the left and right sides was not significant. The linear relationship between anatomical acetabular orientation and PI was not evident in the normal population. Our finding thus proves the absence of a linear relationship between the upper and lower articular orientation of the pelvic segment and deepens the understanding of the characteristics of acetabular orientation and PI.

How much does lumbar fusion change sagittal pelvic tilt in individuals receiving total hip arthroplasty?

Background

This study primarily aims to examine the effect of lumbar fusion on changes in sagittal pelvic tilt (SPT) in total hip arthroplasty (THA) patients.

Methods

We reviewed 19 hip osteoarthritic patients undergoing THA with or without lumbar fusion. The gender, age, primary disease, Deyo comorbidity score, and year of surgery were sorted and matched. All patients were followed up for at least 12 months. They were compared in terms of the SPT angle, Harris hip score (HHS) and complications.

Results

On average, the patients receiving lumbar fusion had a − 3.9 (95% CI − 7.7 to − 1.5) degrees of SPT before THA and − 2.7 (95% CI − 6.5 to 1.1) degrees postoperatively, and the THA patients without lumbar fusion averaged 2.5 (95% CI − 0.1 to 5.0) degrees and 4.2 (95% CI 2.0 to 6.4) degrees, respectively. In the lumbar fusion patients, the mean SPT was − 3.9 (95% CI − 9.9 to 2.0) degrees with L5S1 fusion and − 4.0(95% CI − 10.0 to 2.1) degrees without L5S1 fusion on the standing radiograph before THA (t = 0.01, P = 0.99). The mean SPT was − 1.2 (95% CI − 4.9 to 2.6) degrees with one- and two-segment fusion and − 10.0 (95% CI − 18.5 to 1.5) degrees with three- and four-segment fusion before THA (t = 2.60, P = 0.02). There was no statistically significant difference in cup inclination and cup anteversion after THA between the lumbar fusion and control groups. These patients in the two groups achieved a similar HHS 12 months after THA despite the fact that they had different SPT and HHS before THA.

Conclusion

Lumbar fusion appears to increase the posterior SPT by approximately 6 degrees in the patients undergoing THA. Lumbar fusion of more than two segments is a predictor of more posterior SPT changes, but fusion of L5S1 is not.