Faculty Bibliography

AIMS/OBJECTIVE:Spinopelvic mobility plays an important role in functional acetabular component position following total hip arthroplasty (THA). The primary aim of this study was to determine if spinopelvic hypermobility persists or resolves following THA. Our second aim was to identify patient demographic or radiological factors associated with hypermobility and resolution of hypermobility after THA. METHODS:) ≥ 30°. Radiological spinopelvic parameters, including SS, pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, anterior pelvic plane tilt (APPt), and spinopelvic tilt (SPT), were measured on preoperative imaging, and at six weeks and a minimum of one year postoperatively. The severity of bilateral hip osteoarthritis (OA) was graded using Kellgren-Lawrence criteria. RESULTS:increased from baseline (11.4° (SD 8.8°)) to one year after THA by 11.5° (SD 7.4°) (p < 0.001), which correlates to an 8.5° (SD 5.5°) mean decrease in seated functional cup anteversion. Contralateral hip OA was the only radiological predictor of hypermobility persisting at one year after surgery. The overall reoperation rate was 1.5%. CONCLUSION/CONCLUSIONS: 2021;103-B(12):1766-1773.

BACKGROUND:Imageless computer navigation improves component placement accuracy in total hip arthroplasty (THA), but variations in the registration process are known to impact final accuracy measurements. We sought to evaluate the registration accuracy of an imageless navigation device during THA performed in the lateral decubitus position. METHODS:A prospective, observational study of 94 patients undergoing a primary THA with imageless navigation assistance was conducted. Patient position was registered using 4 planes of reference: the patient's coronal plane (standard method), the long axis of the surgical table (longitudinal plane), the lumbosacral spine (lumbosacral plane), and the plane intersecting the greater trochanter and glenoid fossa (hip-shoulder plane). Navigation measurements of cup position for each plane were compared to measurements from postoperative radiographs. RESULTS:Mean inclination from radiographs (41.5° ± 5.6°) did not differ significantly from inclination using the coronal plane (40.9° ± 3.9°, P = .39), the hip-shoulder plane (42.4° ± 4.7°, P = .26), or the longitudinal plane (41.2° ± 4.3°, P = .66). Inclination measured using the lumbosacral plane (45.8° ± 4.3°) differed significantly from radiographic measurements (P < .0001). Anteversion measured from radiographs (mean: 26.1° ± 5.4°) did not differ significantly from the hip-shoulder plane (26.6° ± 5.2°, P = .50). All other planes differed significantly from radiographs: coronal (22.6° ± 6.8°, P = .001), lumbosacral (32.5° ± 6.4°, P < .0001), and longitudinal (23.7° ± 5.2°, P < .0001). CONCLUSION/CONCLUSIONS:Patient registration using any plane approximating the long axis of the body provided a frame of reference that accurately measured intraoperative cup position. Registration using a plane approximating the hip-shoulder axis, however, provided the most accurate and consistent measurement of acetabular component position.

CASE:A 69-year-old woman underwent revision total knee arthroplasty for patellar component aseptic loosening. The periprosthetic tissue demonstrated histologic features of an adaptive immune response (aseptic lymphocyte-dominant vasculitis-associated lesion [ALVAL]). No particles of corrosion debris were identified. The inflammation seemed to be associated with zirconium oxide (ZrO2) particles added as a bone cement radio-opacifier. CONCLUSION:The factors responsible for the adaptive immune response cannot be determined with certainty; however, this is the first reported case of ALVAL associated with ZrO2-containing bone cement. Previous reports describing ALVAL around failed total knee prostheses have not included observations about the type of contrast material added to cement.

»:Mental health and psychosocial factors play a critical role in clinical outcomes in orthopaedic surgery. »:The biopsychosocial model of disease defines health as a product of physiology, psychology, and social factors and, traditionally, has not been as emphasized in the care of musculoskeletal disease. »:Improvement in postoperative outcomes and patient satisfaction is incumbent upon the screening, recognition, assessment, and possible referral of patients with high-risk psychosocial factors both before and after the surgical procedure.

BACKGROUND:Under current Medicare bundled payment programs, when a patient undergoes a subsequent elective procedure within the 90-day episode-of-care, the first procedure is excluded from the bundle and a new episode-of-care initiated. The purpose of this study was to determine if staging bilateral total hip (THA) and total knee arthroplasty (TKA) procedures within 90 days have an effect on bundled episode-of-care costs. METHODS:We reviewed a consecutive series of Medicare patients undergoing staged primary THA and TKA from 2015-2019. Patients who underwent a prior procedure within 90 days were compared to those who had undergone a procedure 90-120 days prior. We then performed a multivariate analysis to identify the independent effect of staging timeframe on costs and outcomes. RESULTS:Of the 136 patients undergoing a staged bilateral THA or TKA, 48 patients underwent staged procedures within 90 days (35%) and 88 patients between 91-120 days (65%). There were no significant differences observed for demographics, comorbidities, complications, readmissions, or discharge disposition (all P > .05). Patients undergoing a staged procedure within 90 days had increased episode-of-care costs by $2021 (95% CI $11-$4032, P = .049), increased postacute care costs by $2019 (95% CI $66-$3971, P < .001), and reduced per-patient margin by $2868 (95% CI-$866-$4869, P = .005). DISCUSSION/CONCLUSIONS:Patients undergoing staged bilateral THA or TKA within 90 days have increased episode-of-care costs compared to those undergoing a staged procedure from 91-120 days. Since patients may still not be fully recovered from the first procedure, CMS should address the inappropriate allocation of costs to ensure institutions are not penalized.

BACKGROUND:Patients with adverse spinopelvic mobility have higher complication rates following total hip arthroplasty (THA). Risk factors include a stiff lumbar spine, standing posterior pelvic tilt ≤ -10°, and a severe sagittal spinal deformity (pelvic incidence minus lumbar lordosis mismatch ≥20°). The purpose of this study is to define the spinopelvic risk factors and quantify the prevalence of risk factors for pathologic spinopelvic mobility. METHODS:A retrospective cohort analysis from January 2014 to February 2020 was performed on a multicenter series of 9414 primary THAs by 168 surgeons, all with preoperative spinopelvic measurements in the supine, standing, and flex-seated positions. All patients were included. The prevalence of adverse spinopelvic mobility and frequency of each spinopelvic risk factor was calculated. RESULTS:The cohort was 52% female, 48% male, with an average age of 65 years. Thirteen percent of patients exhibited adverse spinopelvic mobility and 17% had one or more of the 3 risk factors. Adverse mobility was found in 35% of patients with at least 1 risk factor, 47% with at least 2 risk factors, and 57% with all 3 risk factors. CONCLUSION/CONCLUSIONS:Forty-six percent of patients had spinopelvic pathology driven by one or more of the risk factors. Number of risk factors present and risk of adverse spinopelvic mobility were positively correlated, with 57% of patients with all 3 risk factors exhibiting adverse spinopelvic mobility. Although this study defines the prevalence of these risk factors in this highly selected cohort, it does not report incidence in a general THA population. LEVEL OF EVIDENCE/METHODS:Prognostic Level IV.

BACKGROUND:Patients with spinopelvic pathology, including lumbar spine stiffness and sagittal spinal deformity, are at increased risk for postoperative complications, including instability, dislocation, and revision after total hip arthroplasty (THA). Recent evidence has suggested that the Lewinnek safe zone should no longer be considered an appropriate target for all patients, especially those with spinopelvic pathology, as the safe zone is a dynamic rather than static target. There are 2 distinct issues for arthroplasty surgeons to consider: lumbar spinal stiffness and sagittal spinal deformity, each of which has its own management. METHODS:In order to manage patients with spinopelvic pathology undergoing THA, a basic understanding of spinopelvic parameters, including sagittal balance, sacral slope, and anterior pelvic plane, is essential. Techniques outlined in this manuscript describe a systematic preoperative work-up and intraoperative management of acetabular component positioning according to patient-specific spinopelvic parameters, ensuring optimal component placement and a reduced risk for impingement, instability, and poor postoperative outcomes. RESULTS:Evaluation of each patient's spinopelvic parameters informs patient classification according to the Hip-Spine Classification for THA. Patient classification is determined by the presence of spinal stiffness and spinal deformity, with corresponding scoring and classification into one of the 4 categories used to determine risk for postoperative dislocation, define patient-specific cup positioning, and create their functional safe zone. CONCLUSION/CONCLUSIONS:A simple 2-step preoperative assessment with measurements of the anterior pelvic plane and the sacral slope on standing and seated lateral X-rays will identify patients at high risk for postoperative dislocation due to spinal deformity and/or stiffness. Accounting for spinopelvic pathology and adhering to the Hip-Spine Classification guidelines for acetabular component positioning can help reduce the burden of instability and revisions in this complex patient population.

Understanding spinopelvic motion and the dynamic relationship of the hip, spine, and pelvis is essential in decreasing the risk of instability after total hip arthroplasty. The hip-spine relationship is complex, and a detailed analysis of each patient's spinopelvic mobility is warranted to help guide safe acetabular component positioning. Through the use of a standing anteroposterior pelvis X-ray, lateral spinopelvic radiographs in the standing and seated position, and advanced functional imaging, key spinopelvic parameters can be obtained. A systematic preoperative workup can help to identify hip-spine pathology that predisposes patients to instability, and can help in planning and establishing a patient-specific "safe zone." Based on the presence of concomitant hip-spine pathology, patients must be evaluated thoroughly with preoperative imaging to plan for the optimal target acetabular cup position. This paper guides readers through important parameters and imaging associated to spinopelvic motion as it relates to total hip arthroplasty stability.

AIMS/OBJECTIVE:Patients with spinal pathology who undergo total hip arthroplasty (THA) have an increased risk of dislocation and revision. The aim of this study was to determine if the use of the Hip-Spine Classification system in these patients would result in a decreased rate of postoperative dislocation in patients with spinal pathology. METHODS:This prospective, multicentre study evaluated 3,777 consecutive patients undergoing THA by three surgeons, between January 2014 and December 2019. They were categorized using The Hip-Spine Classification system: group 1 with normal spinal alignment; group 2 with a flatback deformity, group 2A with normal spinal mobility, and group 2B with a stiff spine. Flatback deformity was defined by a pelvic incidence minus lumbar lordosis of > 10°, and spinal stiffness was defined by < 10° change in sacral slope from standing to seated. Each category determined a patient-specific component positioning. Survivorship free of dislocation was recorded and spinopelvic measurements were compared for reliability using intraclass correlation coefficient. RESULTS:A total of 2,081 patients met the inclusion criteria. There were 987 group 1A, 232 group 1B, 715 group 2A, and 147 group 2B patients. A total of 70 patients had a lumbar fusion, most had L4-5 (16; 23%) or L4-S1 (12; 17%) fusions; 51 patients (73%) had one or two levels fused, and 19 (27%) had > three levels fused. Dual mobility (DM) components were used in 166 patients (8%), including all of those in group 2B and with > three level fusions. Survivorship free of dislocation at five years was 99.2% with a 0.8% dislocation rate. The correlation coefficient was 0.83 (95% confidence interval 0.89 to 0.91). CONCLUSION/CONCLUSIONS: 2021;103-B(7 Supple B):17-24.