Female Sex and Longer Fusion Constructs Significantly Increase the Risk of Total Hip Arthroplasty Following Spinal Fusion

Patients with Hip Osteoarthritis Have a Higher Rate of Spinal Reoperation Following Lumbar Spinal Fusion

BACKGROUND

Lumbar spinal pathology is known to affect outcomes following total hip arthroplasty (THA). However, the effect of hip osteoarthritis (OA) on outcomes following lumbar fusion has not been well studied. The purpose of this study was to determine the association between hip OA and spinal reoperation following lumbar spinal fusion.

METHODS

The 5% Medicare Part B claims database was queried for all patients who underwent primary elective lumbar fusion from 2005 to 2019. Patients were divided into 2 groups: those who underwent elective THA within 1 year after primary lumbar fusion, indicating that they had severe hip OA at the time of lumbar fusion, and those who underwent lumbar fusion with no diagnosed hip OA and no THA during the study period. Exclusion criteria included THA as a result of trauma, revision THA or primary THA in the 5-year period before primary lumbar fusion, <65 years of age, and no enrollment in the database for 5 years before and 1 year after primary lumbar fusion. The primary outcome was spinal reoperation within 1, 3, and 5 years. Multivariable Cox regression was performed with age, sex, diabetes, heart disease, obesity, smoking status, osteoporosis, number of levels fused, use of posterior instrumentation, use of an interbody device, use of bone graft, and surgical approach as covariates.

RESULTS

Overall, 1,123 patients (63.4% female; 91.3% White; mean age, 76.8 ± 4.1 years) were included in the hip OA group and 8,893 patients (56.2% female; 91.3% White; mean age, 74.8 ± 4.9 years) were included in the control group. After multivariable analysis, patients with severe hip OA had significantly greater rates of revision surgery at 3 years (odds ratio [OR], 1.61; p < 0.001) and 5 years (OR, 1.87; p < 0.001) after the index lumbar fusion.

CONCLUSIONS

Patients with severe hip OA at the time of primary lumbar fusion had a significantly increased risk of spinal reoperation at 3 and 5 years postoperatively. These data provide further evidence to support performing THA prior to lumbar fusion in the unsettled debate regarding which surgery should be prioritized for patients with simultaneous degenerative diseases of the hip and lumbar spine.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Effect of spinal fusion on joint space narrowing of the hip: comparison among non-fusion, short fusion, and middle or long fusion

BACKGROUND

Lumbar fusion corrects spinal deformities and improves spinal complications. Hip osteoarthritis (OA) is strongly correlated with spinal mobility, and joint space narrowing of the hip after spinal fusion has gained attention. This study aimed to elucidate the effect of spinal fusion on hip joint space narrowing.

MATERIALS AND METHODS

We retrospectively examined 530 hips of 270 patients who underwent spinal surgery. All the patients underwent whole-spine radiography before and at the final follow-up. Patients were divided into three groups (N group: non-spinal fusion, S group: up to three interbody fusions, and L group: more than four interbody fusions). The rates of joint space narrowing, spinal parameters (sagittal vertical axis, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence), and limb length discrepancy at the final follow-up were compared. A multilinear regression analysis was performed to identify the risk factors for the rate of joint space narrowing.

RESULTS

The rate of joint space narrowing was significantly higher in the L group than in the N and S groups (P < 0.001). No significant difference in the rate of joint space narrowing was observed between the N and S groups. Multiple linear regression analysis revealed that the number of fusion levels (p < 0.05) and follow-up period (p < 0.001) were independent risk factors for joint space narrowing. Spinal parameters at the final follow-up were not independent risk factors.

CONCLUSIONS

Long spinal fusion (more than four levels) led to significantly greater joint space narrowing of the hip than short (up to three levels) or no fusion. Spinal alignment did not affect joint space narrowing of the hip. Surgeons should be aware that more than four interbody fusions may result in worse joint space narrowing of the hip.

LEVEL OF EVIDENCE

IV, retrospective study.

Risk factors of hip joint structural changes following pedicle subtraction osteotomy for ankylosing spondylitis-related thoracolumbar kyphosis: a minimum two-year observation

PURPOSE

To determine the clinical- and surgical-related factors of hip joint structural changes in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis who underwent PSO.

METHODS

Hip involvement was assessed by the Bath Ankylosing Spondylitis Radiology Hip Index (BASRI-h) and defined by a score of at least 2. 52 patients with BASRI-h scores maintained and 78 patients with BASRI-h scores increased during follow-up were retrospectively reviewed. Clinical data were recorded. Radiological assessment was performed preoperatively, postoperatively, and at the final follow-up.

RESULTS

No significant difference existed in age, gender and follow-up time between the groups, but earlier onset of AS, longer disease and kyphotic duration, and worse Bath Ankylosing Spondylitis Functional Index (BASFI) scores at the final follow-up were observed in patients with BASRI-h scores increased (P < 0.05). Besides, global kyphosis (GK), T1-pelvic angle (TPA), pelvic tilt (PT) and anterior pelvic plane angle (APPA) were always larger in patients with BASRI-h scores increased, accompanied with more sacral fixation (P < 0.05). Multivariate logistics regression showed that earlier onset of AS, longer kyphotic duration, larger preoperative GK, sacral fixation and larger APPA during follow-up were independent risk factors.

CONCLUSION

Earlier onset of AS and longer kyphotic duration were the clinical risk factors of hip joint structural changes in AS patients following PSO, while larger preoperative GK, sacral fixation in PSO and larger APPA during follow-up were the surgical-related factors. Surgeons should inform patients with risk factors of the possibility for severe hip joint structural changes after PSO.

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.

The Impact of Spinopelvic Parameters on Hip Degeneration After Spinal Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

This study aimed to investigate the effects of spinopelvic alignment parameters after spinal fusion on the rate of joint space narrowing in nonarthritic hips.

SUMMARY OF BACKGROUND DATA

Spinal fusion affects the forces on the adjacent hip joint. Therefore, hip joint narrowing may be increased after spinal fusion surgery. However, the relationship between spinal alignment and hip degeneration remains unclarified.

METHODS

We retrospectively reviewed data from patients who underwent lumbar spinal fusion from 2011 to 2018 at our institute. Patients with hip osteoarthritis (Kellgren-Lawrence grade ≥II) or hip dysplasia were excluded. The rate of hip joint space narrowing after spinal fusion was measured in 191 patients (382 hips). We assessed the effects of the following spinopelvic alignment parameters on the joint narrowing rate: pelvic tilt, sacral slope (SS), pelvic incidence (PI), lumbar lordosis (LL), PI-LL, sagittal vertical axis, and distance between the C7 plumb line, and the central sacral vertical line (C7-CSVL).

RESULTS

The hip joint narrowing rate was greater when four or more levels were fused compared with single-level fusion. After adjusting for the effects of patient-related factors, the alignment parameters significantly associated with the hip joint narrowing rate were the PI ( P = 0.0002), SS ( P = 0.047), and PI-LL ( P = 0.0022). A subgroup analysis of patients who underwent long fusion (four or more levels combined with iliac screws) also indicated that the PI ( P = 0.013), SS ( P = 0.0054), and PI-LL ( P = 0.046) were associated with the hip joint narrowing rate.

CONCLUSION

The PI, SS, and PI-LL were associated with the progression of hip joint narrowing after spinal fusion, especially after fusion of four or more levels. Surgeons need to be aware of the risk of increased hip joint narrowing in patients with a large PI, SS, and PI-LL after fusion surgery.

Does lumbar spine fusion predispose patients to future total hip replacement?

OBJECTIVE

Hip-spine syndrome has been well studied since it was first described by Offierski and MacNab in 1983. Today, strong evidence links symptoms of hip and spine pathology to postsurgical outcomes. Recent studies have reported increased rates of hip dislocation in patients previously treated with total hip arthroplasty (THA) who had undergone lumbar fusion procedures. However, the effect of this link on native hip-joint degeneration remains an area of ongoing research. The purpose of this study was to characterize the relationship between use of lumbar fusion procedures and acceleration of hip pathology by analyzing the rate of future THA in patients with preexisting hip osteoarthritis.

METHODS

This population-level, retrospective cohort study was conducted by using the PearlDiver research program. The initial patient cohort was defined by the presence of diagnosis codes for hip osteoarthritis. Patients were categorized according to use of lumbar fusion after diagnosis of hip pathology. Survival curves with respect to THA were generated by comparison of the no lumbar fusion cohort with the lumbar fusion cohort. To assess the impact of fusion construct length, the lumbar fusion cohort was then stratified according to the number of levels treated (1-2, 3-7, or ≥ 8 levels). Hazard ratios (HRs) were then calculated for the risk factors of number of levels treated, patient age, and sex.

RESULTS

A total of 2,275,683 patients matched the authors' inclusion criteria. Log-rank analysis showed no significant difference in the rates of THA over time between the no lumbar fusion cohort (2,239,946 patients) and lumbar fusion cohort (35,737 patients; p = 0.40). When patients were stratified according to number of levels treated, again no differences in the incidence rates of THA over the study period were determined (p = 0.30). Patients aged 70-74 years (HR 0.871, p < 0.001), 75-79 years (HR 0.733, p < 0.001), 80-84 years (HR 0.557, p < 0.001), and ≥ 85 years (HR = 0.275, p < 0.001) were less likely to undergo THA relative to the reference group (patients aged 65-69 years).

CONCLUSIONS

Although lumbar fusion was initially hypothesized to have a significant effect on rate of THA, lumbar fusion was not associated with increased need for future THA in patients with preexisting hip osteoarthritis. Additionally, there was no relationship between fusion construct length and rate of THA. Although lumbar fusion reportedly increases the risk of hip dislocation in patients with prior THA, these data suggest that lumbar fusion may not clinically accelerate native hip degeneration.

Number of Levels of Spinal Fusion Associated with the Rate of Joint-Space Narrowing in the Hip

BACKGROUND

Fusion of a joint reportedly increases force in the adjacent joints and leads to progression of arthritis. Whether lumbar spinal fusion increases force in the hip joint and promotes wear of the joint space is unclear. The purpose of this study was to evaluate the rate of joint-space narrowing in the hip following spinal fusion and to examine the effects of the number of levels fused on the joint-narrowing rate.

METHODS

We retrospectively reviewed data for patients who underwent lumbar spinal fusion from 2011 to 2018 at our institute. Patients with a previous hip surgery, Kellgren-Lawrence grade ≥II hip osteoarthritis, hip dysplasia, and rheumatoid arthritis were excluded. The rate of joint-space narrowing in the hip was measured in 205 eligible patients (410 hips) following spinal fusion, and the effects of sex, age, body mass index, indication for spinal fusion, laterality, sacral fixation, and number of levels fused on the narrowing rate were examined.

RESULTS

The rate of joint-space narrowing for all patients was 0.114 ± 0.168 mm/year. The narrowing rate for single-level fusion was 0.062 ± 0.087 mm/year, whereas that for fusion of ≥7 levels was 0.307 ± 0.254 mm/year. In the multivariate regression analysis, only the length of fusion (standardized coefficient [SC] = 0.374, p < 0.0001) was associated with an increased narrowing rate. When the narrowing rate was normalized by height, female sex was another risk factor for increased narrowing (SC = 0.109, p = 0.023). Secondary regression modeling performed with patients who underwent spinal fusion for degenerative disc disease showed that the length of fusion (SC = 0.454, p < 0.0001) and female sex (SC = 0.138, p = 0.033) were associated with increased joint-space narrowing.

CONCLUSIONS

Longer spinal fusion was associated with the progression of hip joint narrowing following spinal fusion. Surgeons should be aware of the possible increased risk of hip degeneration following spinal fusion and should inform patients of this risk.

LEVEL OF EVIDENCE

Level III. See Instructions for Authors for a complete description of levels of evidence.

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.