Dislocation of a primary total hip arthroplasty is more common in patients with a lumbar spinal fusion.
01 May 2017-Journal of Bone and Joint Surgery-british Volume (British Editorial Society of Bone and Joint Surgery)-Iss: 5, pp 585-591
TL;DR: Patients with a previous history of lumbar spinal fusion have a significantly higher rate of dislocation of their THA than age‐ and gender‐matched patients without a lumbAR spinal fusion.
Abstract: Aims Lumbar fusion is known to reduce the variation in pelvic tilt between standing and sitting. A flexible lumbo-pelvic unit increases the stability of total hip arthroplasty (THA) when seated by increasing anterior clearance and acetabular anteversion, thereby preventing impingement of the prosthesis. Lumbar fusion may eliminate this protective pelvic movement. The effect of lumbar fusion on the stability of total hip arthroplasty has not previously been investigated.
Patients and Methods The Medicare database was searched for patients who had undergone THA and spinal fusion between 2005 and 2012. PearlDiver software was used to query the database by the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) procedural code for primary THA and lumbar spinal fusion. Patients who had undergone both lumbar fusion and THA were then divided into three groups: 1 to 2 levels, 3 to 7 levels and 8+ levels of fusion. The rate of dislocation in each group was established using ICD-9-CM codes. Patients who underwent THA without spinal fusion were used as a control group. Statistical significant difference between groups was tested using the chi-squared test, and significance set at p < 0.05.
Results At one-year follow-up, 14 747 patients were found to have had a THA after lumbar spinal fusion (12 079 1 to 2 levels, 2594 3 to 7 levels, 74 8+ levels). The control group consisted of 839 004 patients. The dislocation rate in the control group was 1.55%. A higher rate of dislocation was found in patients with a spinal fusion of 1 to 2 levels (2.96%, p < 0.0001) and 3 to 7 levels (4.12%, p < 0.0001). Patients with 3 to 7 levels of fusion had a higher rate of dislocation than patients with 1 to 2 levels of fusion (odds ratio (OR) = 1.60, p < 0.0001). When groups were matched for age and gender to the unfused cohort, patients with 1 to 2 levels of fusion had an OR of 1.93 (95% confidence interval (CI) 1.42 to 2.32, p < 0.001), and those with 3 to 7 levels of fusion an OR of 2.77 (CI 2.04 to 4.80, p < 0.001) for dislocation.
Conclusion Patients with a previous history of lumbar spinal fusion have a significantly higher rate of dislocation of their THA than age- and gender-matched patients without a lumbar spinal fusion.
Cite this article: Bone Joint J 2017;99-B:585–91.
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TL;DR: Patients with a late dislocation have abnormal spinopelvic motion that precipitates the dislocation, especially when combined with cup malposition or soft-tissue abnormalities.
Abstract: Background Late dislocations after total hip arthroplasty (THA) are challenging for the hip surgeon because the cause is often not evident and recurrence is common. Recently, decreased spinopelvic motion has been implicated as a cause of dislocation. The purpose of this study was to assess the mechanical causes of late dislocation, including the influence of spinopelvic motion. Methods Twenty consecutive patients were studied to identify the cause of their late dislocation. Cup inclination and anteversion were measured on standard pelvic radiographs. Lateral standing and sitting spine-pelvis-hip radiographs were used to measure pelvic motion, femoral mobility, and sagittal cup position by assessing sacral slope, pelvic-femoral angle, and cup ante-inclination. Spinopelvic motion was defined as the difference between the standing and sitting sacral slopes (Δsacral slope). A new measurement, the combined sagittal index, which measures the sagittal acetabular and femoral positions, was used to assess the functional motion of the hip joint and risk of impingement. Results There were 9 anterior dislocations (45%) and 11 posterior dislocations (55%) at a mean of 8.3 years after a primary THA. Eight of the 9 patients with an anterior dislocation had spinopelvic abnormalities such as fixed posterior pelvic tilt when standing, increased standing femoral extension, and an increased standing combined sagittal index. Ten of the 11 patients with a posterior dislocation had abnormal spinopelvic measurements such as decreased spinopelvic motion (average Δsacral slope [and standard error] = 9.0° ± 2.4°), increased femoral flexion, and a decreased sitting combined sagittal index. For every 1° decrease in spinopelvic motion, there was an associated 0.9° increase in femoral motion and, in some patients, this resulted in osseous impingement and dislocation. Conclusions Patients with a late dislocation have abnormal spinopelvic motion that precipitates the dislocation, especially when combined with cup malposition or soft-tissue abnormalities. Spinopelvic stiffness is associated with increased age and increased femoral motion, which may lead to impingement and dislocation. Lateral spine-pelvis-hip radiographs may predict the risk and direction of dislocation. Level of evidence Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
175 citations
TL;DR: This study demonstrates that patients with fixed spinopelvic alignment from standing to sitting position are at higher risk of hip dislocation.
Abstract: Background Sitting radiographs have been used as a pre-operative tool to plan patient-specific total hip arthroplasty (THA) component position that would improve hip stability. Previous work has demonstrated that spinal mobility may impact functional acetabular position when seated. We sought to determine whether patients who dislocate following THA have different sitting spinopelvic alignment or acetabular component orientation compared to patients who did not dislocate. Methods A consecutive series of 1000 patients underwent post-operative low-dose biplanar spine-to-ankle lateral radiographs in standing and sitting positions 1 year following THA. Twelve patients (1% of all patients) experienced hip dislocation. Patients were categorized as having normal lumbar spines (without radiographic arthrosis) or as having lumbar multi-level degenerative disc disease. Measurements of spinopelvic alignment parameters (including sacral slope, lumbar lordosis, and proximal femur angles) and acetabular component orientation in sitting position (functional inclination and functional anteversion) were performed. Results Patients who dislocated had significantly less spine flexion, less change in pelvic tilt, and more hip flexion from standing to sitting positions compared to patients with normal spines. In sitting position, dislocators had acetabular components with less functional inclination and less functional anteversion. Conclusion This study demonstrates that patients with fixed spinopelvic alignment from standing to sitting position are at higher risk of hip dislocation. Imaging patients from standing to sitting position using this technique can provide valuable information on whether a patient has fixed spinopelvic alignment with postural changes and is therefore at higher risk of dislocation.
170 citations
Cites background from "Dislocation of a primary total hip ..."
...Prior st udies have shown patients who have lumbar 200 spine diseases or who have undergone lumbar spine s urg ry are at increased risk of hip 201 instability [8,9,17], indicating the importance of the hip-spine relationship....
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...How patients achieve s itting position through the lumbar-pelvic35 femoral complex continues to be an area of interest given the impact on functional acetabular 36 component position following THA [3,5,7], and arthr oplasty surgeons are becoming increasingly 37 aware that previous spine surgery may be associated wi h poor outcomes after THA [8,9]....
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TL;DR: Spine-pelvis-hip motion is normally coordinated to allow balance of the mass of the trunk and hip motion with standing and sitting.
Abstract: Spine-pelvis-hip motion is normally coordinated to allow balance of the mass of the trunk and hip motion with standing and sitting.Normal motion from standing to sitting involves hip flexion of 55° to 70° and pelvic posterior tilt of 20°. Because the acetabulum is part of the pelvis, as the pelvis t
145 citations
TL;DR: THA is a highly effective procedure with a low overall rate of instability, and a history of spinal fusion was the most significant independent risk factor for dislocation within the first 6 months following THA.
Abstract: Background Dislocation following total hip arthroplasty (THA) continues to be one of the most common reasons for revision THA. The purpose of this study is to measure the current rate of dislocation following THA in the United States. A secondary goal is to identify patients at highest risk of instability after THA. Methods The Nationwide Readmissions Database was used to identify cases of elective primary THA between 2012 and 2014. All readmissions associated with dislocations were identified. Kaplan-Meier curves were used to assess the time to dislocation in the study population. A multivariate logistic regression was modeled to assess risk factors associated with readmission for dislocation. Results A total of 207,285 THAs were identified between 2012 and 2014. Of the total, 2842 dislocation-associated readmissions (1.4%) were identified, at a median of 40 days post-THA. A history of spinal fusion was the strongest independent predictor of dislocation (odds ratio [OR], 2.45; 95% confidence interval [CI], 1.97-3.04; P Conclusion THA is a highly effective procedure with a low overall rate of instability. A history of spinal fusion was the most significant independent risk factor for dislocation within the first 6 months following THA.
125 citations
TL;DR: Previous lumbar spinal fusion increases risk of dislocation and revision, and may negatively impacts patient-reported outcomes after THA, and Orthopaedic surgeons should pay particular attention to these patients.
Abstract: Background The biomechanical relationship between the lumbar spine and the hip is well-documented. It follows that fusing the lumbar spine would have implications on the outcomes of total hip arthroplasty (THA). This study aimed to determine the effect of preexisting lumbar spinal fusion surgery on the outcomes of THA by synthesizing the available evidence via systematic review and meta-analysis. Methods A systematic review with meta-analysis was performed in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Electronic searches were performed in 6 different databases for studies comparing outcomes in patients after THA with or without a history of lumbar fusion. Studies were required to report at least one outcome out of dislocation, revision due to hip instability or patient-reported outcomes. Results Patients with a history of lumbar spinal fusion are at a significantly increased risk of dislocation (relative risk 2.03, P P = .006) after THA. Patient-reported outcomes were also poorer in patients with prior lumbar fusion compared with those without, although meta-analysis could not be performed due to heterogeneity in the outcome measure used between studies. Conclusion Previous lumbar spinal fusion increases risk of dislocation and revision, and may negatively impacts patient-reported outcomes after THA. Orthopaedic surgeons should pay particular attention to these patients and could use patient-specific planning, instrumentation, and targeted counselling to optimize clinical and subjective outcomes. Future studies could clarify the impact of prior fusion on patient-reported outcomes after THA.
119 citations
References
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TL;DR: It was found that anterior dislocations were associated with increased acetabular-component anteversion and there was no significant correlation between cup-orientation angle and posterior dislocation.
Abstract: In a series of 300 total hip replacements, nine (3 per cent) dislocated. Precise measurements of the orientation of the acetabular cup were made and it was found that anterior dislocations were associated with increased acetabular-component anteversion. There was no significant correlation between cup-orientation angle and posterior dislocation. The dislocation rate for cup orientation with anteversion of 15 +/- 10 degrees and lateral opening of 40 +/- 10 degrees was 1.5 per cent, while outside this "safe" range the dislocation rate was 6.1 per cent. Other factors that were documented include time after surgery (with the greatest risk in the first thirty days) and surgical history (with a greater risk in hips that have had prior surgery).
2,407 citations
TL;DR: Operative principles that maximize an impingement-free range of motion include correct combined acetabular and femoral anteversion and an optimal head-neck ratio.
Abstract: Impingement is a cause of poor outcomes of prosthetic hip arthroplasty; it can lead to instability, accelerated wear, and unexplained pain. Impingement is influenced by prosthetic design, component position, biomechanical factors, and patient variables. Evidence linking impingement to dislocation and accelerated wear comes from implant retrieval studies. Operative principles that maximize an impingement-free range of motion include correct combined acetabular and femoral anteversion and an optimal head-neck ratio. Operative techniques for preventing impingement include medialization of the cup to avoid component impingement and restoration of hip offset and length to avoid osseous impingement.
387 citations
TL;DR: The cumulative long-term risk of dislocation after total hip arthroplasty is considerably greater than has been reported in short-term studies and patients at highest risk are female patients and those with a diagnosis of osteonecrosis of the femoral head or an acute fracture or nonunion of the proximal part of the Femur.
Abstract: Background: A widely variable prevalence of dislocation after total hip arthroplasty has been reported, partly because of varying durations of follow-up for this specific end-point. The effect of demographic factors on the long-term risk of dislocation as a function of time after total hip arthroplasty is not well understood. The purpose of the present study was to determine the risk of dislocation as a function of time after Charnley total hip arthroplasty and to investigate the demographic factors that influence the cumulative risk of dislocation.
Methods: Six thousand six hundred and twenty-three consecutive primary Charnley total hip arthroplasties were performed in 5459 patients at one institution between 1969 and 1984. The patients included 2869 female patients and 2590 male patients with a mean age of sixty-three years. All procedures were performed with a 22-mm femoral head, and all femoral and acetabular components were fixed with cement. The patients were followed at routine intervals and were specifically queried about dislocation. The cumulative risk of dislocation was calculated with use of the Kaplan-Meier method.
Results: Three hundred and twenty hips (4.8%) dislocated. The cumulative risk of a first-time dislocation was 1% at one month and 1.9% at one year and then rose at a constant rate of approximately 1% every five years to 7% at twenty-five years for patients who were alive and had not had a revision by that time. Multivariate analysis revealed that the relative risk of dislocation for female patients (as compared with male patients) was 2.1 and that the relative risk for patients who were seventy years old or more (as compared with those who were less than seventy years old) was 1.3. Three underlying diagnoses—osteonecrosis of the femoral head, acute fracture or nonunion of the proximal part of the femur, and inflammatory arthritis—were associated with a significantly greater risk of dislocation than osteoarthritis was.
Conclusions: The cumulative long-term risk of dislocation after total hip arthroplasty is considerably greater than has been reported in short-term studies. The incidence of dislocation is highest in the first year after arthroplasty and then continues at a relatively constant rate for the life of the arthroplasty. Patients at highest risk are female patients and those with a diagnosis of osteonecrosis of the femoral head or an acute fracture or nonunion of the proximal part of the femur.
Level of Evidence: Prognostic study, Level II-1 (retrospective study). See Instructions to Authors for a complete description of levels of evidence.
330 citations
TL;DR: Pelvic tilt makes navigation systems referring to the anterior plane inaccurate, and the resulting cup position measured on standard radiographs, depending on pelvic tilt, is calculated.
Abstract: Background Modern navigation techniques allow precise positioning of the acetabular cup relative to the anterior pelvic plane. Variations in pelvic tilt will affect the resulting spatial orientation of the cup.Methods We measured pelvic tilt in 30 volunteers with an inclinometer combined with an ultrasonographic position measurement system. A mathematical algorithm was developed to calculate the resulting cup position measured on standard radiographs, depending on pelvic tilt.Results Average pelvic tilt at rest was −4° in the lying position and −8° in the standing position, and ranged from −27° to +3°. Pelvic reclination of 1° will lead to functional anteversion of the cup of approximately 0.7°.Interpretation Pelvic tilt makes navigation systems referring to the anterior plane inaccurate.
327 citations
TL;DR: Comprehensive analysis of the pelvic and subpelvic sectors as part of the sagittal, frontal and cross-sectional balance of the trunk sheds new light on some spinal diseases and their relation to the pelvis.
Abstract: Introduction
The role of the pelvic area in sagittal balance is evident for spinal surgeons, but the influence of the coxofemoral joint is underestimated and inadequately explained by conventional imagery. Comprehensive analysis of the pelvic and subpelvic sectors as part of the sagittal, frontal and cross-sectional balance of the trunk sheds new light on some spinal diseases and their relation to the pelvis.
248 citations