Characteristics and Quality of Online Searches for Direct Anterior Versus Posterior Approach for Total Hip Arthroplasty.

BACKGROUND: Online resources are important for patient self-education and reflect public interest. We described commonly asked questions regarding the direct anterior versus posterior approach (DAA, PA) to total hip arthroplasty (THA) and the quality of associated websites. METHODS: We extracted the top 200 questions and websites in Google's "People Also Ask" section for 8 queries on January 8, 2023, and grouped websites and questions into DAA, PA, or comparison. Questions were categorized using Rothwell's classification (fact, policy, value) and THA-relevant subtopics. Websites were evaluated by information source, Journal of the American Medical Association Benchmark Criteria (credibility), DISCERN survey (information quality), and readability. RESULTS: We included 429 question/website combinations (questions: 52.2% DAA, 21.2% PA, 26.6% comparison; websites: 39.0% DAA, 11.0% PA, 9.6% comparison). Per Rothwell's classification, 56.2% of questions were fact, 31.7% value, 10.0% policy, and 2.1% unrelated. The THA-specific question subtopics differed between DAA and PA (P < .001), specifically for recovery timeline (DAA 20.5%, PA 37.4%), indications/management (DAA 13.4%, PA 1.1%), and technical details (DAA 13.8%, PA 5.5%). Information sources differed between DAA (61.7% medical practice/surgeon) and PA websites (44.7% government; P < .001). The median Journal of the American Medical Association Benchmark score was 1 (limited credibility, interquartile range 1 to 2), with the lowest scores for DAA websites (P < .001). The median DISCERN score was 55 ("good" quality, interquartile range 43 to 65), with the highest scores for comparison websites (P < .001). Median Flesch-Kincaid Grade Level scores were 12th grade level for both DAA and PA (P = .94). CONCLUSIONS: Patients' informational interests can guide counseling. Internet searches that explicitly compare THA approaches yielded websites that provide higher-quality information. Providers may also advise patients that physician websites and websites only describing the DAA may have less balanced perspectives, and limited information regarding surgical approaches is available from social media resources.

Functional Acetabular Component Positioning During Direct Anterior Approach Hip Arthroplasty Using a Novel Three-Dimensional Virtual Mesh Imaging System With Fluoroscopy.

BACKGROUND: Optimal position of total hip arthroplasty (THA) components is critical for joint mechanics and stability. Acetabular component positioning during supine surgery in direct anterior approach (DAA) THA may be different in the standing position postoperatively, which traditional fluoroscopy is unable to predict. A novel 3-dimensional (3D) image analysis technology (IAT) that uses artificial intelligence to measure the tilt and rotation of the pelvis has enabled prediction of component positioning from supine to standing. The purpose of this study was to compare intraoperative fluoroscopy, non-3D-IAT, and 3D-IAT with postoperative standing radiographs to assess the accuracy of component positioning. METHODS: From 2022 to 2023, 30 consecutive patients (86.6% women, mean age 59 [range, 55 to 67]) undergoing primary DAA THA with the use of the 3D-IAT were identified. A separate cohort of 148 patients from 2020 to 2021 (85% women, mean age 65 [range, 55 to 69]) who underwent DAA THA with non-3D-IAT was used for comparison. Leg length discrepancy (LLD), cup anteversion, and inclination were manually measured on intraoperative fluoroscopic images and digitally measured using IAT. Follow-up evaluation occurred at 1 month with standing pelvis radiographs measured using Ein Bild Röntgen Analyze-Cup software. Measurements were compared via Wilcoxon signed rank tests where P ≤ .05 indicates significantly different measurements. RESULTS: Median LLD, inclination, and anteversion measurements via non-3D-IAT and fluoroscopy were significantly different compared to postoperative standing radiographs (P < .001). The 3D-IAT more accurately predicted LLD, abduction, and anteversion, with values not significantly different from postoperative standing measurements (P = .23, P = .93, and P = .36, respectively). CONCLUSIONS: The use of the 3D-IAT during DAA THA allowed for the more accurate prediction of acetabular component position in the standing position postoperatively.

Clinical outcomes and return to dance after total hip arthroplasty or hip resurfacing in professional dancers.

Aims: Professional dancers represent a unique patient population in the setting of hip arthroplasty, given the high degree of hip strength and mobility required by their profession. We sought to determine the clinical outcomes and ability to return to professional dance after total hip arthroplasty (THA) or hip resurfacing arthroplasty (HRA). Methods: Active professional dancers who underwent primary THA or HRA at a single institution with minimum one-year follow-up were included in the study. Primary outcomes included the rate of return to professional dance, three patient-reported outcome measures (PROMs) (modified Harris Hip Score (mHHS), Hip disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS-JR), and Lower Extremity Activity Scale (LEAS)), and postoperative complications. Results: A total of 49 hips in 39 patients (mean age 56 years (SD 13); 80% female (n = 39)) were included. Mean follow-up was 4.9 years (SD 5.1). Of these 49 hips, 37 THAs and 12 HRAs were performed. In all, 96% of hips returned to professional dance activities postoperatively. With regard to PROMs, there were statistically significant improvements in mHHS, HOOS-JR, and LEAS from baseline to ≥ one year postoperatively. There were complications in 7/49 hips postoperatively (14%), five of which required revision surgery (10%). There were no revisions for instability after the index procedure. Two complications (5.4%) occurred in hips that underwent THA compared with five (42%) after HRA (p = 0.007), though the difference by procedure was not significantly different when including only contemporary implant designs (p = 0.334). Conclusion: Active professional dancers experienced significant improvements in functional outcome scores after THA or HRA, with a 96% rate of return to professional dance. However, the revision rate at short- to mid-term follow-up highlights the challenges of performing hip arthroplasty in this demanding patient population. Further investigation is required to determine the results of THA versus HRA using contemporary implant designs in these patients.

Can generative artificial intelligence pass the orthopaedic board examination?

Background: Resident training programs in the US use the Orthopaedic In-Training Examination (OITE) developed by the American Academy of Orthopaedic Surgeons (AAOS) to assess the current knowledge of their residents and to identify the residents at risk of failing the Amerian Board of Orthopaedic Surgery (ABOS) examination. Optimal strategies for OITE preparation are constantly being explored. There may be a role for Large Language Models (LLMs) in orthopaedic resident education. ChatGPT, an LLM launched in late 2022 has demonstrated the ability to produce accurate, detailed answers, potentially enabling it to aid in medical education and clinical decision-making. The purpose of this study is to evaluate the performance of ChatGPT on Orthopaedic In-Training Examinations using Self-Assessment Exams from the AAOS database and approved literature as a proxy for the Orthopaedic Board Examination. Methods: 301 SAE questions from the AAOS database and associated AAOS literature were input into ChatGPT's interface in a question and multiple-choice format and the answers were then analyzed to determine which answer choice was selected. A new chat was used for every question. All answers were recorded, categorized, and compared to the answer given by the OITE and SAE exams, noting whether the answer was right or wrong. Results: Of the 301 questions asked, ChatGPT was able to correctly answer 183 (60.8%) of them. The subjects with the highest percentage of correct questions were basic science (81%), oncology (72.7%, shoulder and elbow (71.9%), and sports (71.4%). The questions were further subdivided into 3 groups: those about management, diagnosis, or knowledge recall. There were 86 management questions and 47 were correct (54.7%), 45 diagnosis questions with 32 correct (71.7%), and 168 knowledge recall questions with 102 correct (60.7%). Conclusions: ChatGPT has the potential to provide orthopedic educators and trainees with accurate clinical conclusions for the majority of board-style questions, although its reasoning should be carefully analyzed for accuracy and clinical validity. As such, its usefulness in a clinical educational context is currently limited but rapidly evolving. Clinical relevance: ChatGPT can access a multitude of medical data and may help provide accurate answers to clinical questions.

Assessment of Risk Factors and Rate of Conversion to Total Hip Arthroplasty Within 2 Years After Hip Arthroscopy Utilizing a Large Database of Commercially Insured Patients in the United States.

Background: The conversion rate of hip arthroscopy (HA) to total hip arthroplasty (THA) has been reported to be as high as 10%. Despite identifying factors that increase the risk of conversion, current studies do not stratify patients by type of arthroscopic procedure. Purpose/Hypothesis: To analyze the rate and predictors of conversion to THA within 2 years after HA. It was hypothesized that osteoarthritis (OA) and increased patient age would negatively affect the survivorship of HA. Study Design: Cohort study; Evidence level, 3. Methods: The IBM MarketScan database was utilized to identify patients who underwent HA and converted to THA within 2 years at inpatient and outpatient facilities between 2013 and 2017. Patients were split into 3 procedure cohorts as follows: (1) femoroacetabular osteoplasty (FAO), which included treatment for femoroacetabular impingement; (2) isolated debridement; and (3) isolated labral repair. Cohort characteristics were compared using standardized differences. Conversion rates between the 3 cohorts were compared using chi-square tests. The relationship between age and conversion was assessed using linear regression. Predictors of conversion were analyzed using multivariable logistic regression. The median time to conversion was estimated using Kaplan-Meier tests. Results: A total of 5048 patients were identified, and the rates of conversion to THA were 12.86% for isolated debridement, 8.67% for isolated labral repair, and 6.76% for FAO (standardized difference, 0.138). The isolated labral repair cohort had the shortest median time to conversion (isolated labral repair, 10.88 months; isolated debridement, 10.98 months; and FAO, 11.9 months [P = .034). For patients >50 years, isolated debridement had the highest rate of conversion at 18.8%. The conversion rate increased linearly with age. Factors that increased the odds of conversion to THA were OA, having an isolated debridement procedure, and older patient age (P < .05). Conclusion: Older patients and those with preexisting OA of the hip were at a significantly increased risk of failing HA and requiring a total hip replacement within 2 years of the index procedure. Younger patients were at low risk of requiring a conversion procedure no matter which arthroscopic procedure was performed.

There Is Wide Variation in Platelet-rich Plasma Injection Pricing: A United States Nationwide Study of Top Orthopaedic Hospitals.

BACKGROUND: Demand for platelet-rich plasma (PRP) injections for osteoarthritis has dramatically increased in recent years despite conflicting evidence regarding its efficacy and highly variable pricing in the top orthopaedic centers in the United States, because PRP is typically not covered by insurance. A previous study investigating the mean price of PRP injections obtained information only from centers advertising online the availability of PRP injections. Thus, there is a need for further clarification of the overall availability and variability in cost of PRP injections in the orthopaedic community as well as an analysis of relevant regional demographic and hospital characteristics that could be associated with PRP pricing. QUESTIONS/PURPOSES: Our study purposes were to (1) report the availability and price variation of knee PRP injections at top-ranked United States orthopaedic centers, (2) characterize the availability of pricing information for a PRP injection over the telephone, (3) determine whether hospital characteristics (Orthopaedic Score [ U . S. News & World Report measure of hospital orthopaedic department performance], size, teaching status, and rural-urban status) were associated with PRP injection availability and pricing, and (4) characterize the price variation, if it exists, of PRP injections in three metropolitan areas and individual institutions. METHODS: In this prospective study, a scripted telephone call to publicly listed clinic telephone numbers was used to determine the availability and price estimate (amount to be paid by the patient) of a PRP injection for knee osteoarthritis from the top 25 hospitals from each United States Census region selected from the U.S. News & World Report ranking of best hospitals for orthopaedics. Univariable analyses examined factors associated with PRP injection availability and willingness to disclose pricing, differences across regions, and the association between hospital characteristics (Orthopaedic Score, size, teaching status, and rural-urban status) and pricing. The Orthopaedic Score is a score assigned to each hospital by U . S. News & World Report as a measure of hospital performance based partly on patient outcomes, with higher scores indicating better outcomes. RESULTS: Overall, 87% (87 of 100) of respondents stated they offered PRP injections. Pricing ranged from USD 350 to USD 2815 (median USD 800) per injection, with the highest prices in the Northeast. The largest price range was in the Midwest, where more than two-thirds of PRP injections given at hospitals that disclosed pricing cost USD 500 to USD 1000. Of the hospitals that offered PRP injections, 68% (59 of 87) were willing to disclose price information over the telephone. PRP injection pricing was inversely correlated with hospital Orthopaedic Score (-3% price change [95% CI -5% to -1%]; p = 0.01) and not associated with any of the other hospital characteristics that were studied, such as patient population median income and total hospital expenses. An intracity analysis revealed wide variations in PRP pricing in all metropolitan areas that were analyzed, ranging from a minimum of USD 300 within 10 miles of metropolitan area B to a maximum of USD 1269 within 20 miles of metropolitan area C. CONCLUSION: We found that although PRP injections are widely available, pricing continues to be a substantial financial burden on patients, with large price variability among institutions. We also found that if patients are willing to shop around in a metropolitan area, there is potential to save a meaningful amount of money. CLINICAL RELEVANCE: As public interest in biologics in orthopaedic surgery increases, knowledge of its pricing should be clarified to consumers. The debated efficacy of PRP injections, combined with our findings that it is an expensive out-of-pocket procedure, suggests that PRP has limited cost-effectiveness, with variable, discrete pricing. As such, the price of PRP injections should be clearly disclosed to patients so they can make informed healthcare decisions.

Prior COVID-19 and Venous Thromboembolism Risk in Total Joint Arthroplasty in Patients Over 65 Years of Age.

BACKGROUND: The COVID-19 pandemic has been associated with increased risks of venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE). However, there is limited literature investigating prothrombotic states and complications after total hip arthroplasty (THA) and total knee arthroplasty (TKA). We investigated (1) trends in VTE, PE, and DVT rates post-THA and TKA from 2016 to 2019 compared to 2020 to 2021 and (2) associations between prior COVID-19 diagnosis and VTE, PE, and DVT. METHODS: A national dataset was queried for elective THA and TKA cases from 2016 to 2021. We first assessed trends in 90-day VTE prevalence between 2016 to 2019 and 2020 to 2021. Second, we investigated associations between previous COVID-19 and 90-day VTE with regression models. RESULTS: From 2016 to 2021, a total of 2,422,051 cases had an annual decreasing VTE prevalence from 2.2 to 1.9% (THA) and 2.5 to 2.2% (TKA). This was evident for both PE and DVT (all trend tests P < .001). After adjusting for covariates (including vaccination status), prior COVID-19 was associated with significantly increased odds of developing VTE in TKA patients (odds ratio 1.2, 95% confidence interval 1.1 to 1.4, P = .007), but not DVT or PE (P > .05). There were no significant associations between prior COVID-19 and VTE, DVT, or PE after THA (P > .05). CONCLUSIONS: Our study suggests that a previous diagnosis of COVID-19 is associated with increased odds of VTE, but not DVT or PE, in TKA patients. Ongoing data monitoring is needed given our effect estimates, emerging COVID-19 variants, and evolving vaccination rates.

Thromboembolic prophylaxis in spine surgery: an analysis of ChatGPT recommendations.

BACKGROUND CONTEXT: Venous thromboembolism is a negative outcome of elective spine surgery. However, the use of thromboembolic chemoprophylaxis in this patient population is controversial due to the possible increased risk of epidural hematoma. ChatGPT is an artificial intelligence model which may be able to generate recommendations for thromboembolic prophylaxis in spine surgery. PURPOSE: To evaluate the accuracy of ChatGPT recommendations for thromboembolic prophylaxis in spine surgery. STUDY DESIGN/SETTING: Comparative analysis. PATIENT SAMPLE: None. OUTCOME MEASURES: Accuracy, over-conclusiveness, supplemental, and incompleteness of ChatGPT responses compared to the North American Spine Society (NASS) clinical guidelines. METHODS: ChatGPT was prompted with questions from the 2009 NASS clinical guidelines for antithrombotic therapies and evaluated for concordance with the clinical guidelines. ChatGPT-3.5 responses were obtained on March 5, 2023, and ChatGPT-4.0 responses were obtained on April 7, 2023. A ChatGPT response was classified as accurate if it did not contradict the clinical guideline. Three additional categories were created to further evaluate the ChatGPT responses in comparison to the NASS guidelines: over-conclusiveness, supplementary, and incompleteness. ChatGPT was classified as over-conclusive if it made a recommendation where the NASS guideline did not provide one. ChatGPT was classified as supplementary if it included additional relevant information not specified by the NASS guideline. ChatGPT was classified as incomplete if it failed to provide relevant information included in the NASS guideline. RESULTS: Twelve clinical guidelines were evaluated in total. Compared to the NASS clinical guidelines, ChatGPT-3.5 was accurate in 4 (33%) of its responses while ChatGPT-4.0 was accurate in 11 (92%) responses. ChatGPT-3.5 was over-conclusive in 6 (50%) of its responses while ChatGPT-4.0 was over-conclusive in 1 (8%) response. ChatGPT-3.5 provided supplemental information in 8 (67%) of its responses, and ChatGPT-4.0 provided supplemental information in 11 (92%) responses. Four (33%) responses from ChatGPT-3.5 were incomplete, and 4 (33%) responses from ChatGPT-4.0 were incomplete. CONCLUSIONS: ChatGPT was able to provide recommendations for thromboembolic prophylaxis with reasonable accuracy. ChatGPT-3.5 tended to cite nonexistent sources and was more likely to give specific recommendations while ChatGPT-4.0 was more conservative in its answers. As ChatGPT is continuously updated, further validation is needed before it can be used as a guideline for clinical practice.

Weekend Admission Increases Risk of Readmissions Following Elective Cervical Spinal Fusion.

OBJECTIVE: The "weekend effect" occurs when patients cared for during weekends versus weekdays experience worse outcomes. But reasons for this effect are unclear, especially amongst patients undergoing elective cervical spinal fusion (ECSF). Our aim was to analyze whether index weekend admission affects 30- and 90-day readmission rates post-ECSF. METHODS: All ECSF patients > 18 years were retrospectively identified from the 2016-2018 Healthcare Cost and Utilization Project Nationwide Readmissions Database (NRD), using unique patient linkage codes and International Classification of Diseases, Tenth Revision codes. Patient demographics, comorbidities, and outcomes were analyzed. Univariate logistic regression analyzed primary outcomes of 30- and 90-day readmission rates in weekday or weekend groups. Multivariate regression determined the impact of complications on readmission rates. RESULTS: Compared to the weekday group (n = 125,590), the weekend group (n = 1,026) held a higher percentage of Medicare/Medicaid insurance, incurred higher costs, had longer length of stay, and fewer routine home discharge (all p < 0.001). There was no difference in comorbidity burden between weekend versus weekday admissions, as measured by the Elixhauser Comorbidity Index (p = 0.527). Weekend admissions had higher 30-day (4.30% vs. 7.60%, p < 0.001) and 90-day (7.80% vs. 16.10%, p < 0.001) readmission rates, even after adjusting for sex, age, insurance status, and comorbidities. All-cause complication rates were higher for weekend admissions (8.62% vs. 12.7%, p < 0.001), specifically deep vein thrombosis, infection, neurological conditions, and pulmonary embolism. CONCLUSION: Index weekend admission increases 30- and 90-day readmission rates after ECSF. In patients undergoing ECSF on weekends, postoperative care for patients at risk for specific complications will allow for improved outcomes and health care utilization.

Novel Use of an Accelerometer to Assess Load Asymmetry Over Time After Hip Resurfacing Arthroplasty.

BACKGROUND: There is limited knowledge regarding usage of wearable technology to guide return to sport after hip resurfacing arthroplasty (HRA). This study evaluated the use of accelerometers to identify when symmetry is restored between operative and nonoperative limbs. METHODS: A total of 26 primary HRA patients performed 5 validated physical tests before, 3 and 6 months after HRA: broad jump, double-leg vertical jump (DLVJ), hop test, lateral single-leg jump (LSLJ), and vertical single-leg jump. Impact load and average intensity data (g-force units) were collected using accelerometers. Strength data (pounds [lbs.]) for internal and external rotation were collected with a dynamometer. Univariate and correlation analyses analyzed interlimb asymmetries. RESULTS: At preoperation, there were significant impact load asymmetries for DLVJ (P = .008), hop test (P = .021), and LSLJ (P = .003) and intensity asymmetry for DLVJ (P = .010) and LSLJ (P = .003). At 3 months, there was impact load asymmetry for DLVJ (P = .005) and LSLJ (P = .005) and intensity asymmetry for broad jump (P = .020), hop test (P = .042), and LSLJ (P = .005). There were significant strength asymmetries at preoperation and 3 months postoperation for internal (P = .013) and external rotation (P = .037). All significant asymmetries indicated the nonoperative leg had greater output. No significant asymmetries were found for any exercises at 6 months postoperation. An increase in Harris Hip Score was significantly associated with a decrease in impact asymmetry (rs = -0.269, P = .006). CONCLUSION: Impact loads and strength reach interlimb symmetry at 6 months post-HRA. Wearable accelerometers provide useful metrics to distinguish limb asymmetries for recovery monitoring.

Exuberant Rice Body Formation Associated with Adverse Local Tissue Reaction After Hip Resurfacing Arthroplasty: A Case Report and Review of the Literature.

CASE: A 65-year-old man with osteoarthritis of the hip developed a soft-tissue mass of the inferior gluteal region 3 years after metal-on-metal resurfacing hip arthroplasty. Clinical and imaging findings suggested an adverse local tissue reaction. Intraoperatively, nearly 1 liter of intra-articular fibrinous loose bodies (rice bodies) was removed, and histology showed features of an adaptive immune response. The patient had no evidence of an autoimmune disease or mycobacterial infection. CONCLUSION: To our knowledge, this is the first reported case of florid rice bodies associated with a metal-on-metal hip arthroplasty and adverse local tissue reaction.

Relationships Between Preoperative Mental Health and Improvements in Patient-Reported Outcomes After Total Hip and Knee Arthroplasty.

BACKGROUND: Poor preoperative mental health has been associated with worse outcomes after total hip (THA) and total knee arthroplasty (TKA). To fully understand these relationships, we assessed post-THA and post-TKA improvements in patient-reported mental and joint health by preoperative mental health groups. METHODS: Elective cases (367 THA, 462 TKA) were subgrouped by low (<25th percentile), middle (25th-74th), and high (≥75th) preoperative mental health, using Veterans RAND 12-Item Health Survey Mental Component Summary (MCS) scores. In each subgroup, we assessed the relationship between preoperative MCS and 1-year postoperative change in mental and joint health. Pairwise comparisons and multivariable regression models were applied for THA and TKA separately. RESULTS: Median postoperative mental health change was +14.0 points for the low-MCS THA group, +11.1 low-TKA, +2.0 middle-THA and TKA, -4.0 high-THA, and -4.9 high-TKA (between-group differences P < .001). All MCS groups had improved median joint health scores, without significant between-group differences. Preoperative mental health was negatively associated with mental health improvements in all groups (B = -0.94 - -0.68, P < .001-P = .01) but with improvements in joint health only in the low-THA group (B = -0.74, P = .02). Improvements in mental and joint health were positively associated for low and middle (B = 0.61-0.87, P < .001), but not for high-MCS groups, with this relationship differing for the low versus high group. CONCLUSION: Patients who have low preoperative mental health experienced greater postoperative mental health improvement and similar joint health improvement compared to patients who have high preoperative mental health. Findings can guide subgroup-targeted surgical decision-making and preoperative counseling.

Erratum: Author Correction: The influence of HLA genotype on the development of metal hypersensitivity following joint replacement.

[This corrects the article DOI: 10.1038/s43856-022-00137-0.].

Can robotic technology mitigate the learning curve of total hip arthroplasty?

AIMS: Traditionally, acetabular component insertion during total hip arthroplasty (THA) is visually assisted in the posterior approach and fluoroscopically assisted in the anterior approach. The present study examined the accuracy of a new surgeon during anterior (NSA) and posterior (NSP) THA using robotic arm-assisted technology compared to two experienced surgeons using traditional methods. METHODS: Prospectively collected data was reviewed for 120 patients at two institutions. Data were collected on the first 30 anterior approach and the first 30 posterior approach surgeries performed by a newly graduated arthroplasty surgeon (all using robotic arm-assisted technology) and was compared to standard THA by an experienced anterior (SSA) and posterior surgeon (SSP). Acetabular component inclination, version, and leg length were calculated postoperatively and differences calculated based on postoperative film measurement. RESULTS: Demographic data were similar between groups with the exception of BMI being lower in the NSA group (27.98 vs 25.2; p = 0.005). Operating time and total time in operating room (TTOR) was lower in the SSA (p < 0.001) and TTOR was higher in the NSP group (p = 0.014). Planned versus postoperative leg length discrepancy were similar among both anterior and posterior surgeries (p > 0.104). Planned versus postoperative abduction and anteversion were similar among the NSA and SSA (p > 0.425), whereas planned versus postoperative abduction and anteversion were lower in the NSP (p < 0.001). Outliers > 10 mm from planned leg length were present in one case of the SSP and NSP, with none in the anterior groups. There were no outliers > 10° in anterior or posterior for abduction in all surgeons. The SSP had six outliers > 10° in anteversion while the NSP had none (p = 0.004); the SSA had no outliers for anteversion while the NSA had one (p = 0.500). CONCLUSION: Robotic arm-assisted technology allowed a newly trained surgeon to produce similarly accurate results and outcomes as experienced surgeons in anterior and posterior hip arthroplasty. Cite this article: Bone Jt Open 2021;2(6):365-370.

A Comparative Cohort Study With a 20-Year Age Gap: Hip Resurfacing in Patients Aged ≤35 Years and Patients Aged ≥55 Years.

BACKGROUND: This single-center retrospective cohort study aimed to evaluate and compare implant survival and patient-reported outcome measures in 2 distinct age groups separated by 20 years who underwent hip resurfacing arthroplasty (HRA). METHODS: Between 2005 and 2014, 2042 HRAs were performed by a single-surgeon, and 75 and 377 hips from patients aged ≤35 years and ≥55 years, respectively, were included in this study. Implant survival was determined for all available hips. Clinical features and patient-reported outcome measures were collected. RESULTS: Seven hips were revised, 4 for aseptic loosening of one or both components, one for infection, one for accelerated wear and metallosis, and one for femoral neck fracture. There was no difference in all-cause 10-year revision, with 97.1% (95% confidence interval 80.9 to 99.6) and 99.6% (95% confidence interval: 97 to 99.9) survivorship in younger and older patients, respectively (P = .246). Preoperatively, younger patients were less active than older patients on the Lower Extremity Activity Scale (LEAS) or University of California, Los Angeles, activity scale, but at follow-up, younger patients outpaced older ones. CONCLUSION: Original to our study was the isolation and comparison of 2 distinct age groups. With excellent results in disparate age groups, HRA can be applied to a broad patient demographic and is suitable for those patients who want to achieve a high activity level as defined by Lower Extremity Activity Scale or University of California, Los Angeles, scores.