Analysis of Research Productivity of Orthopedic Surgery Residency Applicants.

Background Orthopedic surgery has become an increasingly competitive specialty. With a pass-fail Step 1, an even greater emphasis on research has been placed to allow candidates to better distinguish themselves. This study analyzes the scholarly activity of accepted orthopedic residency applicants during medical school, assessing what factors, including the novel altmetric attention score, may be associated with greater research productivity. Methods A list of orthopedic residency programs was obtained from the Electronic Residency Application Service (ERAS). A total of 688 orthopedic residents from 180 programs who matriculated in 2020 from allopathic medical schools were identified. Resident demographic information and bibliometric data (total publications, orthopedic-related publications, h-index, and altmetric score) of publications published from July 1, 2016, to September 1, 2020, were collected. Descriptive statistics were calculated. Kruskal-Wallis tests analyzed the association between medical school characteristics and research productivity using Stata® 17.0 (StataCorp LLC, College Station, Texas). Results Postgraduate-Year-3 orthopedic residents (N=688) published 2,600 articles during medical school, averaging 3.8 articles per resident. The residents from a top 25 medical school for research had publication counts, altmetric scores, and h-indices, on average, that were higher than those from non-top 25 medical schools for research. Over 150 residents had no publications, and ~10 residents had more than 30 publications. Conclusions The results illustrate that medical school research status influences the research productivity of applicants. Also, given the average number of publications, most research listed on applications are abstracts and presentations. Utilization of the altmetric score may not yet be the best way of examining research experience because orthopedic applicants do not appear to use social networks for academic research.

Spinal anesthesia is a grossly underutilized gold standard in primary total joint arthroplasty: propensity-matched analysis of a national surgical quality database.

BACKGROUND: There is currently no consensus regarding the optimal anesthetic technique for total hip and knee arthroplasty (THA, TKA). This study aimed to compare the utilization rates and safety of spinal vs. general anesthesia in contemporary THA/TKA practice. METHODS: Using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP), a retrospective review of 307,076 patients undergoing total hip or knee arthroplasty under either spinal or general anesthesia between January 2015 and December 2018 was performed. Propensity matching was used to compare differences in operative times, hospital length of stay, discharge destination, and 30-day adverse events. The annual utilization rates for both techniques between 2011 and 2018 were also assessed. RESULTS: Patients receiving spinal anesthesia had a shorter length of stay (P < 0.001) for TKA while no statistical differences in length of stay were observed for THA. Patients were also less likely to experience any 30-day complication (OR = 0.82, P <0.001 and OR = 0.92, P < 0.001 for THA and TKA, respectively) while being more likely to be discharged to home (OR = 1.46, P < 0.001 and OR = 1.44, P < 0.001 for THA and TKA, respectively). Between 2011 and 2018, spinal anesthesia utilization only increased by 1.4% for THA (P < 0.001) and decreased by 0.2% for TKA (P < 0.001), reaching 38.1% and 40.3%, respectively. CONCLUSION: Spinal anesthesia remains a grossly underutilized tool despite providing better perioperative outcomes compared to general anesthesia. As orthopedic surgeons navigate the challenges of value-based care, spinal anesthesia represents an invaluable tool that should be considered the gold standard in elective, primary total hip and knee arthroplasty.

National trends in distribution of underrepresented minorities within United States general surgery residency programs: A longitudinal panel study.

BACKGROUND: Cultural affinity with a provider improves satisfactoriness of healthcare. We examined 2005-2019 trends in racial/ethnic diversity/inclusion within general surgery residency programs. METHODS: We triangulated 2005-2019 race/ethnicity data from Association of American Medical Colleges surveys of 4th-year medical students, the Electronic Residency Application Service, and Accreditation Council for Graduate Medical Education-affiliated general surgery residencies. Temporal trends in minority representation were tested for significance. RESULTS: Underrepresented racial/ethnic minorities in medicine (URiMs) increased among graduating MDs from 7.6% in 2005 to 11.8% in 2019 (p < 0.0001), as did their proportion among surgery residency applicants during 2005-2019 (p < 0.0001). However, proportions of URiMs among general surgery residents (≈8.5%), and of programs without URiMs (≈18.8%), stagnated. CONCLUSIONS: Growing URiM proportions among medical school graduates and surgery residency applicants did not improve URiM representation among surgery trainees nor shrink the percentage of programs without URiMs. Deeper research into motivators underlying URiMs' residency program preferences is warranted.

Hospital Readmissions After Total Joint Arthroplasty: An Updated Analysis and Implications for Value-Based Care.

BACKGROUND: While risk factors have been published for readmissions following primary total joint arthroplasty, little is known about the etiology of those costly adverse events. In this study, we sought to identify the reasons for 30-day readmission following primary total joint arthroplasty in a contemporary national patient sample. METHODS: The American College of Surgeons National Surgical Quality Improvement Program was queried to identify 367,199 patients who underwent primary total knee (TKA) or hip arthroplasty (THA) between 2011 and 2018. The primary outcomes were the annual rates of 30-day readmissions and the causes of those readmissions. RESULTS: The 30-day readmission rate trended downward from 4.5% in 2011 to 3.3% in 2018. Medical complications accounted for 52.6% and 38.5% of readmissions following TKA and THA, respectively. Diseases of the circulatory system, abnormal laboratory values, and diseases of the digestive system were the leading causes of medical readmissions. Surgical complications accounted for 37.7% and 50.7% of readmissions following TKA and THA, respectively. Surgical site infections/wound disruption and venous thromboembolism were the leading two causes of surgical readmissions for THA and TKA. Prosthetic complications-namely dislocations and periprosthetic fractures-were the third leading cause of surgical readmissions for THA. For TKA, musculoskeletal conditions-namely pain and hematoma-were the third leading cause of surgical readmissions. CONCLUSION: Medical complications accounted for half of all TKA readmissions and more than a third of THA readmissions. This could penalize institutions participating in value-based payment programs or dissuade others who are considering participation in such programs.

Incidence and risk factors for acute kidney injury after total joint arthroplasty.

BACKGROUND: Acute kidney injury (AKI) is one of the most common medical causes for readmission following total joint arthroplasty (TJA). This study aimed to (1) examine whether the incidence of AKI has changed over the past decade with the adoption of modern perioperative care pathways and (2) identify the risk factors and concomitant adverse events (AEs) associated with AKI. METHODS: 535,291 primary TJA procedures from the American College of Surgeons National Surgical Quality Improvement Program from 2011 to 2018 were retrospectively reviewed. The annual incidence of AKI was analyzed for significant changes over time. Matched cohort analyses were performed to identify the risk factors and AEs associated with AKI using multivariate logistic regression. RESULTS: The mean incidence of AKI was 0.051%, which remained unchanged during the study period (P = 0.121). Factors associated with AKI were diabetes (OR 1.96, P = 0.009), bilateral procedure (OR 6.93, P = 0.030), lower preoperative hematocrit level (OR 1.09, P = 0.015), body mass index (OR 1.04, P = 0.025), and higher preoperative BUN (OR 1.03, P = 0.043). AKI was associated with length of stay (LOS) > 2 days (OR 4.73, P <  0.001), non-home discharge (OR 0.25, P <  0.001), 30-day readmission (OR 12.29, P <  0.001), and mortality (OR 130.7, P <  0.001). CONCLUSIONS: The incidence of AKI has not changed over the past decade, and it remains a major bundle buster resulting in greater LOS, non-home discharge, readmissions, and mortality. Avoidance of bilateral TJA in patients with DM and high BMI as well as preoperative optimization of anemia and BUN levels are advised.

Sodium Abnormalities Are an Independent Predictor of Complications in Total Joint Arthroplasty: A Cautionary Tale!

BACKGROUND: Electrolyte levels are commonly obtained as part of the preoperative workup for total joint arthroplasty, but limited information exists on the interplay between electrolyte abnormalities and outcomes. METHODS: The National Surgical Quality Improvement Program was queried for primary, elective total hip arthroplasty and total knee arthroplasty (THA, TKA) performed between 2011 and 2017. Three patient groups were compared: normal (control), hypernatremia, and hyponatremia. The primary outcomes were length of stay (LOS) and 30-day adverse events: complications, readmissions, reoperations, and mortality. RESULTS: A total of 244,538 TKAs and 145,134 THAs were analyzed. The prevalence of hyponatremia and hypernatremia was 6.9% and 1.0%, respectively. After controlling for any baseline differences, hypernatremia was an independent predictor of ventilation >48 hours (THA, odds ratio [OR] 3.53), unplanned intubation (THA, OR 3.14), cardiac arrest (THA, OR 2.42), pneumonia (THA, OR 2.16), Clostridium difficile infection (OR 4.66 and 3.25 for THA and TKA, respectively), LOS >2 days (THA, OR 1.16), and mortality (THA, OR 4.69). Similarly, hyponatremia was an independent predictor of LOS >2 days (TKA, OR 1.21), readmission (TKA, OR 1.40), reoperation (OR 1.32 and 1.47 for THA and TKA, respectively), surgical site infections (OR 1.39 and 1.54 for THA and TKA, respectively), and transfusion (OR 1.13 and 1.20 for THA and TKA, respectively). CONCLUSION: As the focus of total joint arthroplasty continues to shift toward value-based payment models and outpatient surgery, caution should be exercised in patients with abnormal preoperative sodium levels, particularly hypernatremia, because of significantly increased risk of prolonged LOS and 30-day adverse events.

Early and Direct Rehab Transfer Leads to Significant Cost Savings and Decreased Hospital Length of Stay for Total Joint Arthroplasty in a Veteran Population.

BACKGROUND: Total joint arthroplasty is the most common elective orthopedic procedure in the Veterans Affairs hospital system. In 2019, physical medicine and rehabilitation began screening patients before surgery to select candidates for direct transfer to acute rehab after surgery. The primary outcome of this study was to demonstrate that the accelerated program was successful in decreasing inpatient costs and length of stay (LOS). The secondary outcome was to show that there was no increase in complication, reoperation, and readmission rates. METHODS: A retrospective review of total joint arthroplasty patients was conducted with three cohorts: 1) control (n = 193), 2) transfer to rehab orders on postop day #1 (n = 178), and 3) direct transfers to rehab (n = 173). To assess for demographic disparities between cohorts, multiple analysis of variance tests followed by a Bonferroni P-value correction were used. Differences between test groups regarding primary outcomes were assessed with analysis of variance tests followed by pairwise t-tests with Bonferroni P-value corrections. RESULTS: There were no significant differences between the cohort demographics or comorbidities. The mean total LOS decreased from 7.0 days in the first cohort, to 6.9 in the second, and 6.0 in the third (P = .00034). The mean decrease in cost per patient was $14,006 between cohorts 1 and 3, equating to over $5.6 million in savings annually. There was no significant change in preintervention and postintervention short-term complications (P = .295). CONCLUSIONS: Significant cost savings and decrease in total LOS was observed. In the current health care climate focused on value-based care, a similar intervention could be applied nationwide to improve Veterans Affair services.

Time Trends in Perioperative Characteristics and Health Outcomes in Hispanic Patients Undergoing Primary Total Knee Arthroplasty.

OBJECTIVE: This study analyzed the yearly trends in procedure utilization, comorbidity profiles, hospital length of stay (LOS), and 30-day outcomes in Hispanic/Latino patients undergoing primary total knee arthroplasty (TKA). Risk stratification for the development of postsurgical adverse events (AEs) was also investigated. METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) was queried for all Hispanic/Latino patients who underwent primary, elective TKA between 2011 and 2017. Thirty-day outcomes and risk factors were determined using multivariate models that controlled for baseline and perioperative differences. RESULTS: A total of 12,767 Hispanic/Latino patients were identified. Over the study period, the rate of TKA utilization increased by 108%. During the same time, there were significant reductions in the rates of COPD (1.9% vs. 2.9%, p = 0.015), anemia (18.0% vs. 23.5%, p < 0.001), dyspnea (2.9% vs. 4.0%, p = 0.006), and procedure length > 100 min (35.2% vs. 39.4%, p < 0.001). Postoperatively, there was a significant decrease in LOS > 2 days (41.3% vs. 75.6%, p < 0.001), but there was an increase in the rate of developing 30-day AEs (5.8% vs. 4.7%, p = 0.046). Independent risk factors for 30-day AEs included age > 65 years, male sex, chronic steroid use, ASA > 2, diabetes, bleeding disorder, chronic kidney disease, and procedure length > 100 min. CONCLUSION: While the recent trends in procedure utilization, comorbidity profiles, and LOS in Hispanic/Latino patients undergoing primary TKA are reassuring, these have not been accompanied with improved postoperative safety. Patients with bleeding disorders, chronic steroid use, and those admitted from facilities other than home appear to be at highest risk for developing 30-day AEs.

Total Hip Arthroplasty in Black/African American Patients: an Updated Nationwide Analysis.

BACKGROUND: The purpose of this was to investigate recent trends in procedure utilization, comorbidity profiles, hospital length of stay (LOS), 30-day outcomes, and risk factors for adverse events (AEs) among Black patients undergoing total hip arthroplasty (THA). METHODS: Using the American College of Surgeons National Surgery Quality Improvement Program, we retrospectively reviewed all Black patients who underwent elective, primary THA between 2011 and 2017. Mixed effects logistic regression analyses were performed to determine the trends in the study outcomes across each individual year. Multivariate logistic regression analyses were performed to identify independent risk factors for AEs. RESULTS: A total of 11,574 Black patients were analyzed. Over the study period, there was an increase by 109% in THA procedures performed in this racial group. During the same time, there were reductions in the prevalence of anemia, dyspnea, tobacco smoking, and osteonecrosis (p < 0.001). The rates of 30-day surgical complications, readmissions, reoperations, and mortality remained unchanged. Only the rate of medical complications demonstrated improvement, driven by a decrease in the incidence of postoperative myocardial infarction (p < 0.001). There was also a significant reduction in LOS > 2 days (68 to 37%, p < 0.001). Independent risk factors for AEs were body mass index > 35, American Society of Anesthesiologists score > 2, dependent functional status, diabetes, bleeding disorders, chronic kidney disease, and osteonecrosis as the surgical indication. CONCLUSION: Between 2011 and 2017, there were improving trends in procedure utilization, comorbidity profiles, and LOS among Black patients undergoing primary THA, but the overall rates of 30-day outcomes remained unchanged. We identified a number of risk factors that may help guide preoperative optimization and patient counseling to mitigate postoperative AEs.

Where Do We Stand Today on Racial and Ethnic Health Inequities? Analysis of Primary Total Knee Arthroplasty from a 2011-2017 National Database.

BACKGROUND: The objective of this study was to present contemporary national data on the state of racial and ethnic disparities pertaining to primary total knee arthroplasty (TKA) in the USA. METHODS: The 2011-2017 National Surgical Quality Improvement Program was used to capture all patients who underwent primary TKA. The study outcomes were differences in demographic, comorbidity burden, perioperative factors, procedure utilization, hospital length of stay (LOS), and 30-day outcomes. The five major minority groups as defined by the National Institutes of Health were compared to non-Hispanic Whites. RESULTS: In total, 262,954 patient records were analyzed, with racial identification available on 230,712 patients (87.7%). White patients accounted for 72.5% of all TKA procedures. There were higher rates of diabetes, hypertension, anemia, and prolonged surgery times among racial and ethnic minorities (p < 0.001). Baseline disparities were especially pronounced among non-Hispanic Blacks/African Americans who were also like to have higher rates of tobacco smoking and CHF (p < 0.001). After controlling for baseline differences, significant disparities in outcomes persisted, especially among Blacks/African Americans and Hispanics/Latinos who had higher odds for experiencing complications and readmissions (p < 0.001). All racial and ethnic groups, except Asians, had longer LOS (p < 0.001). Asian patients had significantly lower rates of readmissions, reoperations, and overall complications (p < 0.001). CONCLUSION: Racial and ethnic disparities remain a public health challenge for patients undergoing TKA. While initiatives aimed at improving preoperative disease-burden and comorbidity profiles represent an important step, they alone are insufficient to fully account for or eliminate the disparities in TKA outcomes.

Perception of Risk: A Poll of American Association of Hip and Knee Surgeons Members.

BACKGROUND: Providers of total hip and knee replacements are being judged regarding quality/cost by payers using competition-based performance measures with poor medical and no socioeconomic risk adjustment. Providers might assume that other providers shed risk and the perception of added risk can influence practice. A poll was collected to examine such perceptions. METHODS: In 2019 a poll was sent to the 2800 surgeon members of the American Association of Hip and Knee Surgeons using Survey Monkey while protecting respondent anonymity/confidentiality. The questions asked whether the perception of poorly risk-adjusted medical comorbidities and socioeconomic risk factors influence surgeons to selectively offer surgery. RESULTS: There were 474 surgeon responses. Prior to elective total hip arthroplasty/total knee arthroplasty, 95% address modifiable risk factors; 52% require a body mass index <40, 64% smoking cessation, 96% an adequate hemoglobin A1C; 82% check nutrition; and 63% expect control of alcohol 2. Due to lack of socioeconomic risk adjustment, 83% reported feeling pressure to avoid/restrict access to patients with limited social support, specifically the following: Medicaid/underinsured, 81%; African Americans, 29%; Hispanics/ethnicities, 27%; and low socioeconomic status, 73%. Of the respondents, 93% predicted increased access to care with more appropriate risk adjustment. CONCLUSION: Competition-based quality/cost performance measures influence surgeons to focus on medical risk factors in offering lower extremity arthroplasty. The lack of socioeconomic risk adjustment leads to perceptions of added risk from such factors as well. This leads to marginal loss of access for patients within certain medical and socioeconomic classes, contributing to existing healthcare disparities. This represents an unintended consequence of competition-based performance measures.

Where Do We Stand Today on Racial and Ethnic Health Disparities? An Analysis of Primary Total Hip Arthroplasty From a 2011-2017 National Database.

BACKGROUND: Little is known about the persistence of health disparities in joint arthroplasty. The objective of this study was to update our knowledge on the state of racial and ethnic disparities in total hip arthroplasty (THA). METHODS: Patients undergoing primary, elective THA using the 2011-2017 American College of Surgeons National Surgical Quality Improvement Program were retrospectively reviewed. Five minority groups (non-Hispanic black or African American, Hispanic or Latino, Asian, American Indian or Alaska Native, and Native Hawaiian or Pacific Islander) were compared with non-Hispanic whites. The primary outcomes were in the differences in demographic characteristics, comorbidities, perioperative characteristics, THA utilization, length of stay (LOS), and 30-day adverse events (mortality, readmission, reoperation, and complications). RESULTS: A total of 155,870 patients were identified with racial and ethnic data available on 134,961 (86.6%) of them. Non-Hispanic white patients comprised 74.5% of all THA procedures. Except for Asians, all minority groups were more likely to be younger, have a higher body mass index, and smoke tobacco (P < .001). There were higher rates of nonprimary osteoarthritis, procedure length exceeding 100 minutes, and comorbidities among all minority groups. All minority groups, except Asian and Hawaiians or Pacific Islanders, were more likely to require an LOS >2 days. Blacks were more likely to develop surgical or medical complications (odds ratio [OR]: 1.21 and 1.2, respectively), whereas Hispanics or Latinos were more likely to develop surgical complications (OR: 1.28). American Indians or Alaska Natives were more likely to undergo reoperations (OR: 1.91). CONCLUSIONS: Health disparities persist among minority groups with respect to comorbidities, THA utilization, LOS, and complications. Blacks and Hispanics or Latinos appear to be the most impacted by these disparities.

Relation of Doximity ranking and matched applicant characteristics in orthopedic residency programs.

Orthopedic surgery residency applicants often turn to data from many online ranking platforms to select programs. The purpose of this study was to determine if programs belonging to different Doximity ranking groups and US geographical regions favor certain applicant characteristics in order to give prospective residents more data to make informed application decisions. 2019 Doximity rankings and matched applicant data from the 2019 Association of American Medical Colleges Residency Navigator were collected and used to determine differences among matched applicant characteristics in Doximity ranking groups and US regions. Matched applicants from the top Doximity ranking group had, on average, significantly more peer-reviewed publications than those of any other ranking group. Among US regions, matched applicants in South Atlantic programs had, on average, significantly fewer peer-reviewed publications than those in Mid Atlantic programs. Residents at South Atlantic programs spent a significantly higher percentage of their first-year training in ambulatory community settings than those in Mid Atlantic, Pacific, or East North Central programs. In conclusion, Doximity ranking is associated with certain applicant qualities more than others, and applicants can use the information in this study to strategically apply to institutions with similar training and educational goals.

Primary Total Hip Arthroplasty in Hispanic/Latino Patients: An Updated Nationwide Analysis of Length of Stay, 30-Day Outcomes, and Risk Factors.

BACKGROUND: This study explored recent time trends in length of stay (LOS), 30-day outcomes, and risk factors for adverse events (AEs) pertaining to total hip arthroplasty in the Hispanic and Latino population. METHODS: A total of 4107 Hispanic and Latino patients who underwent primary total hip arthroplasty between 2011 and 2017 were identified using the American College of Surgeons National Surgical Quality Improvement Program database. Annual trends in LOS and 30-day outcomes (readmission, reoperation, complications, and mortality) were calculated using univariate mixed-effect regression analyses. Risk factors for AEs were determined using multivariate analyses. RESULTS: Between 2011 and 2017, there was a significant reduction in LOS >2 midnights (67.6% to 29.5%, P < .001) among Hispanic patients, which was similar to that among non-Hispanic white patients and was also accompanied with improvements in comorbidity profiles and shorter operative times. Postoperatively, the annual rates of 30-day outcomes were comparable with those of white patients (P > .05). Chronic kidney disease, the American Society of Anesthesiologists score >2, and chronic steroid use were the strongest independent predictors for AEs. CONCLUSIONS: In the context of historically lower arthroplasty outcomes among the Hispanic and Latino population, current evidence suggests a receding tide, with annual trends showing significantly shorter LOS and comparable overall 30-day outcomes with whites. Patients with chronic kidney disease, the American Society of Anesthesiologists score >2, and chronic steroid use are at the highest risk for developing 30-day AEs.

Time Trends and Risk Factors for 30-Day Adverse Events in Black Patients Undergoing Primary Total Knee Arthroplasty.

BACKGROUND: Increased adverse events (AEs) have been reported among black patients undergoing joint arthroplasty, but little is known about their persistence and risk factors. The purpose of this study is (1) to examine recent annual trends in 30-day outcomes after total knee arthroplasty (TKA) and (2) to develop a preoperative risk stratification model in this racial minority. METHODS: The American College of Surgeons National Surgical Quality Improvement Program was queried for all black/African American patients who underwent primary TKA between 2011 and 2017. Time trends in demographic variables, comorbid conditions, perioperative characteristics, length of stay (LOS), and 30-day readmissions, reoperations, medical complications, surgical complications, and mortality were assessed. Multivariate logistic regression analyses were performed to identify independent risk factors for development of 30-day AEs. RESULTS: In total, 19,496 black patients were analyzed. Between 2011 and 2017, there have been improved comorbidity profiles (P < .02), decreased LOS (P < .001), and lower rates of AEs (P < .001). Significant risk factors for developing AEs were male gender, tobacco smoking, American Society of Anesthesiologists score >2, dependent functional status, congestive heart failure, chronic obstructive pulmonary disease, metastatic cancer, dyspnea, chronic kidney disease, bilateral TKA, and operative time >100 minutes. CONCLUSION: There have been significant improvements in the annual trends of LOS and 30-day outcomes among black patients undergoing primary TKA in recent years. A predictive model for 30-day AEs was developed to help guide risk stratification and optimization of modifiable factors, namely anemia, tobacco smoking, bilateral surgery, and operative time.

Minimum twelve-year follow-up of fixed- vs mobile-bearing total knee arthroplasty: Double blinded randomized trial.

BACKGROUND: Total knee arthroplasty (TKA) with fixed-bearing (FB) implants have demonstrated impressive functional results and survival rates. Meanwhile, rotating-platform (RP) constructs have biomechanically shown to reduce polyethylene wear, lower the risk of component loosening, and better replicate anatomic knee motion. There is growing question of the clinical impact these design changes have long-term.Questions/purposes: The aim of this double-blinded prospective randomized trial was to compare function and implant survival in patients who received either FB or RP press-fit condylar Sigma (PFC Sigma, DePuy, Warsaw, IN) total knee replacements at a minimum follow-up of twelve years. PATIENTS AND METHODS: Patient reported outcome measures used included the functional Knee Society Score, Western Ontario and McMaster University Osteoarthritis Index (WOMAC) scores, Medical Outcomes Short Form-36 (SF-36) score, and satisfaction assessment on a four-point Likert scale. The data was collected from times preoperative, two-years, and final encounter (mean 13.95 years). A total of 28 RP and 19 FB knees (58.8%) were analyzed at the final follow-up. RESULTS: Among all patients, KSS and WOMAC scores statistically improved from pre-op to 2-year, while KSS statistically worsened from 2-year to final follow-up. The RP group averaged better follow-up scores in all assessments at the final follow-up with exception of overall satisfaction. There was no statistically significant difference in the functional Knee Society Score, Short Form-36, WOMAC scores, patient satisfaction or implant survival between the two groups at any measured period. CONCLUSIONS: The use of a fixed-bearing or rotating-platform design does not convey significant superiority in terms of function or implant longevity at a minimum twelve years after total knee arthroplasty. LEVEL OF EVIDENCE: Level I, Experimental study, randomized controlled trial (RCT).

The continuum of hip range of motion: From soft-tissue restriction to bony impingement.

Traditional studies of hip kinematics have not identified which anatomic structures limit the range of motion (ROM) when the hip is placed in different maneuvers. In this study, we attempted to answer two questions: (a) During which maneuvers is the motion of the hip limited by bony impingement between the femur and pelvis? (b) When is hip ROM determined by the constraint of soft tissues and to what extent? ROM of eight cadaveric hips was measured in 17 maneuvers using a motion capture system. The maneuvers were recreated in silico using 3D CT models of each specimen to detect the occurrence of bony impingement. If bony impingement was not detected, the variable component of 3D hip motion was increased until a collision was detected. The difference between the virtual ROM at the point of bony impingement and the initial ROM measured experimentally was termed as the soft-tissue restriction. The results showed that bony impingement was present in normal hips during maneuvers consisting of high abduction with flexion, and high flexion combined with adduction and internal rotation. At impingement-free maneuvers, the degree of soft tissue restriction varies remarkably, ranging from 4.9° ± 3.8° (internal rotation) at 90° of flexion to 80.0° ± 12.5° (internal rotation) at maximum extension. The findings shed light on the relative contributions of osseous and soft tissues to the motion of the hip in different maneuvers and allow for a better understanding of physical exams of different purposes in diagnosing bone- or soft tissue-related diseases.