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Treatment of Recurrent Dislocation after Total Hip Arthroplasty Using Advanced Imaging and Three-Dimensional Modeling Techniques: A Case Series.

ABSTRACT:

Background

Surgical treatment options for addressing recurrent dislocation after total hip arthroplasty (THA) vary. Identifying impingement mechanisms in an unstable THA may be beneficial in determining appropriate treatment.

Questions/purposes

We sought to assess the effectiveness of developing pre-operative plans for treating hip instability after THA. We used advanced imaging and three-dimensional modeling techniques to perform impingement analyses in patients with unstable THA.

Methods

We evaluated a series of eight patients who would require revision THA to treat recurrent dislocation. Using a pre-operative algorithmic approach, we built patient-specific models and evaluated hip range of motion with computed tomographic scanning and biplanar radiography. This information was used to determine a surgical treatment plan that was then executed intra-operatively. Patients were followed for 2 years to determine whether they experienced another hip dislocation following treatment.

Results

Pre-operative kinematic modeling showed four of the eight patients had limited hip range of motion during flexion and internal rotation; a prominent anterior inferior iliac spine (AIIS) was found to limit hip range of motion in some of these cases. In the other four patients, range of motion was acceptable, suggesting soft-tissue causes of dislocation. No patients in this series experienced dislocation after undergoing revision THA.

Conclusion

Advanced modeling techniques may be useful for identifying the impingement mechanisms responsible for instability after THA. Once variables contributing to limited hip range of motion are identified, surgeons can develop treatment plans to improve patient outcomes. Resecting a hypertrophic AIIS may improve hip range of motion and may be an important consideration for hip surgeons when revising unstable THAs.

SUBMITTER: Sutphen SA

PROVIDER: S-EPMC7749901 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundMany risk factors have been described for dislocation following total hip arthroplasty (THA), yet a patient-specific risk assessment tool remains elusive. The purpose of this study was to develop a high-dimensional, patient-specific risk-stratification nomogram that allows dynamic risk modification based on operative decisions.MethodsIn this study, 29,349 THAs, including 21,978 primary and 7371 revision cases, performed between 1998 and 2018 were evaluated. During a mean 6-year follow-up, 1521 THAs were followed by a dislocation. Patients were characterized, through individual-chart review, according to non-modifiable factors (demographics, indication for THA, spine disease, prior spine surgery, and neurologic disease) and modifiable operative decisions (operative approach, femoral head diameter, and type of acetabular liner [standard, elevated, constrained, or dual-mobility]). Multivariable regression models and nomograms were developed with dislocation as a binary outcome at 1 year and 5 years postoperatively.ResultsDislocation risk, based on patient-specific comorbidities and operative decisions, was wide-ranging-from 0.3% to 13% at 1 year and from 0.4% to 19% at 5 years after primary THA, and from 2% to 32% at 1 year and from 3% to 42% at 5 years after revision THA. In the primary-THA group, the direct anterior approach (hazard ratio [HR] = 0.27) and lateral approach (HR = 0.58) decreased the dislocation risk compared with the posterior approach. After adjusting for the approach in that group, the combination of a ≥36-mm-diameter femoral head and an elevated liner yielded the largest decrease in dislocation risk (HR = 0.28), followed by dual-mobility constructs (HR = 0.48). In the patients who underwent revision THA, the adjusted risk of dislocation was most markedly decreased by the use of a dual-mobility construct (HR = 0.40), followed by a ≥36-mm femoral head and an elevated liner (HR = 0.88). The adjusted risk of dislocation after revision THA was decreased by acetabular revision (HR = 0.58), irrespective of whether other components were revised.ConclusionsOur patient-specific dislocation risk calculator, which was strengthened by our use of a robust multivariable model that accounted for comorbidities associated with instability, demonstrated wide-ranging patient-specific risks based on comorbidity profiles. The resultant nomograms can be used as a screening tool to identify patients at high risk for dislocation following THA and to individualize operative decisions for evidence-based risk mitigation.Level of evidencePrognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Project description:BackgroundTraditional principles for successful outcomes in Total Hip Arthroplasty (THA) have relied largely on placing the socket in the native position and trying to restore static anatomical femoral parameters gauged on X-rays or intra-operative measurement. Stability is conventionally achieved by making appropriate changes during the time of trial reduction. Post-operative complications of dislocation and significant Limb Length Discrepancy (LLD) requiring foot wear modification represents opposite ends of the spectrum from a biomechanical perspective and these continue to be relatively high. A move towards giving more importance to functional dynamic parameters rather than static anatomical parameters and less reliance on stability testing at trial reduction is warranted.MethodsIntraoperative 3D functional balancing of THA without stability testing at trial reduction was practiced in all subjects undergoing THA in our unit from April 2014. To date 1019 patients have had their hips replaced with the same technique. They were followed up till April 2020 for post-operative complications of dislocation and significant LLD needing footwear modification. A secondary cohort of 114 patients from 1st January to December 31st 2017 within this primary group were analyzed clinically and radiologically to ascertain the implications of functional 3D balancing on X-ray parameters, clinical outcome scores (Harris Hip Score and Oxford Hip Score), ability to squat, and subtle subjective post-operative perception of limb lengthening (POPLL).ResultsIn the primary group of 1019 patients, there were only two dislocations and no patient needed footwear modification for LLD. In the detailed analysis of the secondary cohort of 114 patients, the correlation with restoration of static radiological parameters was inconsistent. 40 patients could not squat and 4 patients had subtle subjective post-operative perceived limb lengthening (POPLL). Measured outcomes such as HHS and OHS were improved in all patients with significant statistical significance (P < 0.001).ConclusionThis study underlines the fact that more importance must be given to functional dynamic parameters by 3D balancing of the THA and not on static anatomical X-rays parameters and stability testing during trial reduction. This represents a paradigm shift in the evolution of total hip arthroplasty.Level of evidenceA Level II study. (Data collected from the ongoing prospective study) (http://www.spine.org/Documents/LevelsofEvidenceFinal.pdf).Supplementary informationThe online version contains supplementary material available at 10.1007/s43465-021-00505-3.