Dislocation of a primary total hip arthroplasty is more common in patients with a lumbar spinal fusion

Prevention of Dislocation After Total Hip Arthroplasty

BACKGROUND

Prevention of dislocation after primary total hip arthroplasty (THA) begins with patient preoperative assessment and planning.

METHODS

We performed a literature search to assess historical perspectives and current strategies to prevent dislocation after primary THA. The search yielded 3458 articles, and 154 articles are presented.

RESULTS

Extremes of age, body mass index >30 kg/m², lumbosacral pathology, surgeon experience, and femoral head size influence dislocation rates after THA. There is mixed evidence regarding the effect of neuromuscular disease, sequelae of pediatric hip conditions, and surgical approach on THA instability. Sex, simultaneous bilateral THA, and restrictive postoperative precautions do not influence the dislocation rates of THA. Navigation, robotics, lipped liners, and dual-mobility acetabular components may improve dislocation rates.

CONCLUSIONS

Risks for dislocation should be identified, and measures should be taken to mitigate the risk. Reliance on safe zones of acetabular component positioning is historical. We are in an era of bespoke THA surgery.

The Impact of Spino-Pelvic Alignment on Total Hip Arthroplasty Outcomes: A Critical Analysis of Current Evidence

BACKGROUND

In this review, we (1) evaluated the effect of adult spine deformity (ASD) and its surgical correction on patients who had a total hip arthroplasty (THA); (2) evaluated the outcomes of THA in patients who have had previous spinal fusion; and (3) we presented an algorithm on how to surgically address patients who simultaneously require THA and ASD correction.

METHODS

A comprehensive literature search was conducted. Our final analysis included 14 studies. Overall, there were 3 studies that reported on the impact of ASD on THA outcomes, 6 studies reported on the effect of ASD correction on THA outcomes, and 5 studies reported on the effect of spinal fusion on THA outcomes.

RESULTS

Patients with concurrent ASD and THA are at increased risk of THA dislocations and revisions with studies reporting a compiled 2.9% dislocation rate in 1167 patients. Patients who underwent ASD correction demonstrated a post-operative reduction of acetabular anteversion (mean reduction range 4.96°-11.2°, P < .001) and tilt (mean -7° ± 10°, P < .001). In THA patients with concurrent lumbosacral fusion, dislocation rates ranged between 3% at 1 year and 7.5% at 2 years compared to 0.4%-2.1% dislocation rates in matching cohorts (P < .001).

CONCLUSION

Spine balance can alter THA outcomes, but the exact mechanism is yet to be elucidated. We aimed at bridging the gap between hip and spine surgeons with an up-to-date analysis of the best available evidence and presented an algorithm for approaching patients who may simultaneously need ASD correction and THA.

Risk Factors for Early Dislocation Following Primary Elective Total Hip Arthroplasty

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 < .0001). Parkinson's disease was also significantly associated with dislocation (OR, 1.63; 95% CI, 1.05-2.51; P = .03), as well as dementia (OR, 1.96; 95% CI, 1.13-3.39; P = .02), depression (OR, 1.28; 95% CI, 1.13-1.43; P < .0001), and chronic lung disease (OR, 1.2; 95% CI, 1.07-1.33; P = .001). Inflammatory arthritis and avascular necrosis were independent risk factors for dislocation (OR, 1.56; 95% CI, 1.25-1.97; P < .0001; OR, 1.67; 95% CI, 1.45-1.93; P < .0001).

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.

Investigation of the Unstable Total Hip Arthroplasty

The investigation of recurrent instability after total hip arthroplasty requires a thorough history and physical examination focused on characterizing the dislocation events and the patient factors that contribute to instability. Radiographic studies include plain radiographs, in particular a cross-table lateral, and computed tomography to accurately assess the implant orientation relative to the patient's native anatomy. More advanced imaging such as magnetic resonance imaging may be useful to assess abductor tendon integrity. A classification system, based on etiology of recurrent instability, is available and helpful to guide treatment strategy. Finally, emerging research has debunked the previous characterization of an acetabular "safe zone" and further identified lumbar spine disease and surgical fusion as a significant risk factor for recurrent instability. Current and future research efforts target radiographic assessment of lumbopelvic alignment in diagnosis, treatment, and prevention of recurrent total hip arthroplasty instability.

Prior Lumbar Spinal Fusion is Associated With an Increased Risk of Dislocation and Revision in Total Hip Arthroplasty: A Meta-Analysis

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 < .00001) and revision (relative risk 3.36, 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.