Faculty Bibliography

Introduction/objectives: Routine use of DM may not be a cost-effective measure, but an increasing number of THA candidates have coexisting spinal disorders, substantially increasing their risk for instability. This study seeks to expand our understanding of the cost-effectiveness of dual mobility components as an alternative to standard articulations in this high-risk dislocation population. Methods: A state-transition Markov model with expectedvalue decision analysis was used to evaluate the costeffectiveness of DM cups for high-risk patients who would be at high risk for dislocation within one year of their index THA. Direct and indirect costs of dislocation, incremental DM cost ($1000), quality-adjusted life years (QALY) values and dislocation probabilities were derived from published data. Results: Spine fusion patients were modelled to have a 15% probability of dislocation following primary THA based on published clinical ranges. A hypothetical reduction of 5% in probability of dislocation was deemed clinically plausible with the addition of a DM implant. Under these model parameters, sensitivity analysis was used to identify scenarios for which DM would be cost effective. For example, if the probability of dislocation is 15% with traditional bearings, then the use of DM is cost-effective if it reduces the dislocation risk to 10% and costs less than $640 (Figure 1). However, at its current average selling price ($1000), it would only be cost-effective if it reduces the probability of dislocation from 15% to 7% in this population. Conclusion: Dislocation is a significant complication and spine fusion patients have been shown to be at high risk. Our results indicate that under specific conditions DM cups are cost-effective for this high risk spine fusion population

Introduction/objectives: Diagnosis and treatment of patients with coexisting hip and spine pathologies can be challenging. Patients with sagittal spinopelvic deformity utilize pelvic tilt (PT) and their lower extremities in order to compensate for malalignment. In patients with lower extremity osteoarthritis (OA), these compensatory mechanisms can be compromised, leading to further disability. Methods: Patients > 18 years with SSD [SVA > 50mm, PT > 25degree, or TK > 60degree] were included for analysis. Spinopelvic, lower extremity, and cervical alignment were assessed on standing full-body stereoradiographs. Hip OA severity was graded by Kellgren-Lawrence scale (0-4). Propensity score matching was used to control for age and T1 pelvic angle (TPA). Patients were categorized as limited OA (LOA: grade 0-2) and severe OA (SOA: grade 3-4). Results: A total of 997 patients (LOA=929, SOA=68) were identified meeting inclusion criteria. After PSM, 136 patients (SOA: n=68, LOA n=68) were included in the study. SOA had less PT (17.8degree+/-12.6degree vs 22.6degree+/-8.4degree, p=0.011), TK (42.5degree+/-21.2degree vs 52.3degree+/-20.2degree, p=0.007), higher SVA (71.6 mm+/-47.1 vs 40.7 mm+/-43.9, p<0.001) and T1Spi (+2.3degree+/-6.4degree vs -2.6degree+/-5.5degree, p<0.001) than LOA. SOA also had a lower SFA (194.3degree+/-12.4degree vs 202.4degree+/-9.5degree, p<0.001) and AA (5.9degree+/-3.5degree vs 7.2degree+/-3.6degree, p=0.043), increased P.Shift (49.7mm+/-39.5 vs 19.7mm+/-28.4; p<0.001) and increased GSA (7.7degree+/-4.5degree vs 5.0degree+/-4.0degree, p< 0.001) compared to LOA. There was no difference in PI, PI-LL mismatch, LL, KA or cervical alignment (p >0.05). Conclusion: Patients with coexisting spinal malalignment and severe hip OA compensate by pelvic shift and thoracic hypokyphosis rather than pelvic tilt, likely as a result of limited hip extension

Introduction/objectives: In this study, we evaluate the application of preoperative PRO scores, such as the Hip dysfunction and Osteoarthritis Outcomes Score (HOOS) and EuroQol-5Dimension (EQ-5D), as potential predictive modelling tools to anticipate adverse in-hospital outcomes. Methods: Patients between the ages of 18 to 95 undergoing a primary THA between January 2015 and January 2017 at this institution were chart reviewed for inclusion in this study. 40% of our patient population completed preoperative PRO scores within 1 year of surgery and were included in this study. Nursing documentation was reviewed for patient demographics and in-hospital course metrics, such as visual analogue scale (VAS) for pain and morphine equivalence usages. EQ-5D was noted to be binomially distributed and subsequently transformed into a categorical variable with patients scoring >50% placed into a "high EQ-5D" group, and those scoring below into a "low EQ-5D" group. Results: In total, 349 patients including 157 males and 192 females were recruited for this study. The average age and body mass index (BMI) was 62.4+/-11.0 years and 28.6+/-5.61 kg/m2, respectively. The median American Society of Anesthesiology (ASA) Score within our patient cohort was 2. Of the pre-operative scores, age, BMI, EQ-5D, and HOOS section scores were compared with average daily pain, all but age were significantly correlated. However, these values had low r2 values <0.1, indicating poor predictive strength. Conclusion: Our study demonstrates that baseline PRO scores, such as the HOOS and EQ-5D, contain a small predictive component for in-hospital pain scores and average daily morphine. Furthermore, PRO tools can potentially be used to develop systematic, predictive risk stratification models

Introduction/objectives: Computer-assisted hip navigation offers the potential for more accurate placement of hip components, which is important in avoiding dislocation, impingement, and edge-loading. The purpose of this study was to determine if the use of computer-assisted hip navigation reduced the rate of dislocation in patients undergoing revision THA. Methods: We retrospectively reviewed 72 patients who underwent computer-navigated revision THA between January 2015 and December 2016. Demographic variables, indication for revision, type of procedure, and postoperative complications were collected for all patients. Clinical follow-up was performed at 3 months, 1 year, and 2 years. Results: All 72 patients (48% female; 52% male) were included in the final analysis. Mean age of patients undergoing revision THA was 70.4, mean BMI was 26.4 +/- 5.2 kg/m2. The most common indications for revision THA were instability (31%), aseptic loosening (29%), osteolysis/ eccentric wear (18%), infection (11%), and miscellaneous (11%). During revision procedure, polyethylene component was most commonly changed (46%), followed by femoral head (39%), and acetabular component (15%). At final follow-up, there were no dislocations among all study patients (0%). Compared to preoperative dislocation values, there was a significant reduction in the rate of dislocation with the use of computer- assisted hip navigation (31% vs. 0%; p<0.05). Conclusion: Our study demonstrates a significant reduction in the rate of dislocation following revision THA with the use of computer navigation. Although the cause of postoperative dislocation is often multifactorial, the use of computer- assisted surgery may help to curtail femoral and acetabular malalignment in revision THA

Introduction/objectives: As the chronically infected HCV population ages, the demand for total hip arthroplasty (THA) will increase. Previous reports demonstrate that HCV infection may predispose patients to inferior postoperative outcomes following THA. No study to date has evaluated surgical outcomes in THA recipients that have been successfully treated for HCV. The purpose of the current study was to assess surgical outcomes following THA in patients that have been successfully treated for their HCV infection compared to patients that did not receive treatment. Methods: A retrospective review of all patients diagnosed with HCV that underwent primary unilateral and bilateral THA between January 2006 and April 2017 was conducted. Patients were divided into two cohorts: (1) patients that received treatment for HCV (HCV-T) and (2) patients that did not receive treatment for HCV (HCV-NT). All patient variables including demographics, HCV infection characteristics, operative details, in-hospital complications, clinical follow-up, and revisions were carefully studied. Results: 26 patients (32 hips) were in the HCV-T cohort, and 32 patients (38 hips) were in the HCV-UT cohort. Mean age at surgery was 59.5+/-7.3 and 60.0+/-10.2 years in the HCV-T and HCV-UT cohorts, respectively. Mean follow-up time was 26.3+/-23.4 and 31.7+/-28.3 months in the HCV-T and HCV-UT cohorts, respectively. There were significantly more in- hospital complications (p<0.01) and more patients required THA (p=0.04) in the HCV-UT cohort compared to the HCV-T cohort, respectively. Conclusion: Treatment of HCV prior to primary THA can reduce the incidence of in-hospital complications and need for revision THA. HCV treatment regimens should be a part of patient optimization prior to THA

Introduction/objectives: Nonmodular and modular femoral stems have been associated with complications following revision total hip arthroplasty (rTHA). This study aims to report outcomes of modular and nonmodular femoral components in rTHA. Methods: From January 1st, 2013 to September 30th, 2017, all rTHAs using modular or nonmodular femoral stems were identified. Demographic data including age, gender, American Anesthesiology Society (ASA) score. Surgical details including operative time, length of implant, and implant cost were collected. Clinical outcomes including length of stay (LOS), dislocation, infection, fracture, femoral implant re-revision, reoperation, and mortality were also collected. Simple linear regression analysis and sub-analysis using multivariable logistic regression were performed. Results: Of 247 rTHA cases identified, 136 (55.1%) cases utilized modular stems while 111 (44.9%) cases utilized nonmodular components. The average follow-up was 15.5 months (range 0.5-59 months). Nonmodular stems had a significantly lower cost when compared to modular implants (54.3% of modular cost; p<0.001). There were no differences appreciated in cohort demographics including age (p=0.831), gender (p=0.459), and ASA (p=0.053). In addition, there were no differences observed in the surgical details or clinical outcomes assessed, including operative time (p=0.386), LOS (p=0.638), and rates of re-revision of the femoral implant (p=0.327), re-operation (p=0.410), and post-op complications including, infection (p=0.322), dislocation (p=0.687), fracture (p=0.528), and mortality (p=0.446). Conclusion: The use of distal fixation, tapered-fluted, titanium nonmodular components may offer a more costeffective approach to rTHA compared to their modular counterparts

Introduction/objectives: Surgical correction of instability after total hip arthroplasty (THA) remains a complex challenge to the hip arthroplasty surgeon. At our institution, we have developed a stepwise evaluation and surgical correction strategy for patients presenting with THA instability. Methods: 37 patients presenting to a single surgeon for evaluation of THA instability underwent a standardized pre- operative protocol to determine causative factors leading to instability. Radiographic images were reviewed for leg length, offset, cup inclination and anteversion, and dynamic changes in pelvic tilt from supine to standing, and standing to sitting. Findings were confirmed intraoperatively, and instability was addressed surgically through the stepwise algorithm. Results: 37 consecutive patients have been prospectively revised for THA instability. Average pre-operative acetabular abduction was 47.8 degrees and anteversion was 13.4 degrees. Average pelvic incidence was 38 degrees. The acetabular component alone was revised in 22 patients, and the stem alone in 2 patients. Both acetabular and femoral components were revised in 4 patients. There were 9 cases where the head and liner were exchanged to a larger size. No isolated head or isolated liner exchanges were performed. Dual mobility heads were used in 20 patients (54%), with 40mm heads used in 11 patients and 36mm heads used in 6 patients. Post-operative acetabular abduction was 39.2 degrees (range 37-43) and post-operative anteversion was 27.3 degrees (range 22-34), p<0.003 for both. Conclusion: Using this stepwise evaluation as a tool to guide surgical correction of instability, our study demonstrates a significant and promising decrease in the risk of recurrent instability in this high-risk population

Introduction/objectives: Here we report on the shortterm outcomes of a novel monolithic, tapered, fluted, gritblasted, forged titanium stem. Methods: A multicenter, retrospective study was conducted using institutional databases. Patients were included for this study if they underwent primary or revision THA surgery using this particular monolithic, tapered, fluted, grit-blasted, forged titanium stem. Demographic data was collected including gender, age, race, body mass index (BMI), number of prior hip surgeries, and Charlson Comorbidity Index. Surgical data included reason for revision, femoral bone stock as determined by the Paprosky classification, use of trochanteric osteotomies, and length of stay (LOS). Outcomes data included 30- and 90- day complications and readmissions, revision for any reason, femoral revision free interval, and post-operative implant subsidence assessed on serial radiographs. Results: Sixty-three THAs in 62 patients were included in this study. Mean total subsidence from baseline was 1.615 mm at 2 weeks postoperatively (20/62 hips), 1.595 mm at 6 weeks (21/62 hips), 1.267 mm at 3 months (18 hips), 1.430 mm at 6 months (10/62 hips), and 2.167 mm at 9 months (3/62 hips). Three patients underwent subsequent femoral head and liner exchange within 1 year of surgery: 1 for recurrent dislocation, 2 for early periprosthetic joint infection. Conclusion: In total, only 4 patients in our multicenter case series had progressive subsidence within the first three months postoperatively, while the remaining 34 hips with radiographic data had either no subsidence or clinically insignificant subsidence (<5mm). However, the available data suggests that this monolithic, tapered, fluted, grit-blasted, forged-titanium stem achieves early stable femoral fixation

AIMS/OBJECTIVE:The routine use of dual-mobility (DM) acetabular components in total hip arthroplasty (THA) may not be cost-effective, but an increasing number of patients undergoing THA have a coexisting spinal disorder, which increases the risk of postoperative instability, and these patients may benefit from DM articulations. This study seeks to examine the cost-effectiveness of DM components as an alternative to standard articulations in these patients. PATIENTS AND METHODS/METHODS:A decision analysis model was used to evaluate the cost-effectiveness of using DM components in patients who would be at high risk for dislocation within one year of THA. Direct and indirect costs of dislocation, incremental costs of using DM components, quality-adjusted life-year (QALY) values, and the probabilities of dislocation were derived from published data. The incremental cost-effectiveness ratio (ICER) was established with a willingness-to-pay threshold of $100 000/QALY. Sensitivity analysis was used to examine the impact of variation. RESULTS:In the base case, patients with a spinal deformity were modelled to have an 8% probability of dislocation following primary THA based on published clinical ranges. Sensitivity analysis revealed that, at its current average price ($1000), DM is cost-effective if it reduces the probability of dislocation to 0.9%. The threshold cost at which DM ceased being cost-effective was $1180, while the ICER associated with a DM THA was $71 000 per QALY. CONCLUSION/CONCLUSIONS:These results indicate that under specific clinical and economic thresholds, DM components are a cost-effective form of treatment for patients with spinal deformity who are at high risk of dislocation after THA. Cite this article: Bone Joint J 2018;100-B:1297-1302.

Adverse local tissue reaction, osteolysis, and subsequent increased incidence of failure have been associated with metal-on-metal (MoM) total hip arthroplasty (THA). We present the case of a 68-year-old woman with rheumatoid arthritis who has undergone left THA with a MoM bearing. Seven years postoperatively, she presented with 6 weeks of severe left hip pain. Sequential radiographs and advanced imaging demonstrated a rapid onset of extensive acetabular osteolysis with pelvic discontinuity and pseudotumor formation. She underwent revision THA using a cup-cage construct with a satisfactory outcome. In this article, we review current evidence-based management options for pelvic discontinuity, as well as other complications related to MoM THA.