Mode of Fixation and Survivorship in Primary Total Knee Arthroplasty in the American Joint Replacement Registry.

BACKGROUND: A recent rapid increase in cementless total knee arthroplasty (TKA) has been noted in the American Joint Replacement Registry (AJRR). The purpose of our study was to compare TKA survivorship based on the mode of fixation reported to the AJRR in the Medicare population. METHODS: Primary TKAs from Medicare patients submitted to AJRR from 2012 to 2022 were analyzed. The Medicare and AJRR databases were merged. Cox regression stratified by sex compared revision outcomes (all-cause, infection, mechanical loosening, and fracture) for cemented, cementless, and hybrid fixation, controlling for age and the Charlson comorbidity index (CCI). RESULTS: A total of 634,470 primary TKAs were analyzed. Cementless TKAs were younger (71.8 versus 73.1 years, P < .001) than cemented TKAs and more frequently utilized in men (8.2 versus 5.8% women, P < .001). Regional differences were noted, with cementless fixation more common in the Northeast (10.5%) and South (9.2%) compared to the West (4.4%) and Midwest (4.3%) (P < .001). No significant differences were identified in all-cause revision rates in men or women ≥ 65 for cemented, cementless, or hybrid TKA after adjusting for age and CCI. Significantly lower revision for fracture was identified for cemented compared to cementless and hybrid fixation in women ≥ 65 after adjusting for age and CCI (P = .0169). CONCLUSIONS: No survivorship advantage for all-cause revision was noted based on the mode of fixation in men or women ≥ 65 after adjusting for age and CCI. A significantly lower revision rate for fractures was noted in women ≥ 65 utilizing cemented fixation. Cementless fixation in primary TKA should be used with caution in elderly women.

Variability of pre-operative functional pelvic tilt in total hip arthroplasty patients.

PURPOSE: Pelvic tilt (PT) is important to consider when planning total hip arthroplasty (THA) due to its dynamic impact on acetabular orientation. The degree of sagittal pelvic rotation varies during functional activities and can be difficult to measure without proper imaging. The purpose of this study was to evaluate PT variation in the supine, standing, and seated positions. METHODS: A multi-centre cross-sectional study was performed that included 358 THA patients who had preo-perative PT measured from supine CT scan and standing and upright seated lateral radiographs. Supine, standing, and seated PT and associated changes between functional positions were evaluated. Anterior PT was assigned a positive value. RESULTS: In the supine position, mean PT was 4° (range, -35° to 20°), where 23% had posterior PT and 69% anterior PT. In the standing position, mean PT was 1° (range, -23° to 29°), where 40% had posterior PT and 54% anterior PT. In the seated position, mean PT was -18° (range, -43° to 47°), where 95% had posterior PT and 4% anterior PT. From standing to seated, the pelvis rotated posteriorly in 97% of cases (maximum 60°) with 16% of cases considered stiff (change ≤ 10°) and 18% of cases considered hypermobile (change ≥ 30°). CONCLUSION: Patients undergoing THA have marked PT variation in the supine, standing, and seated positions. There was wide variability in PT change from standing to seated, with 16% of patients considered stiff and 18% considered hypermobile. Functional imaging should be performed on patients prior to THA to allow for more accurate planning.

The Effect of Femoral Fixation on Revision and Mortality Following Elective Total Hip Arthroplasty in Patients Over the Age of 65 years. An Analysis of the American Joint Replacement Registry.

BACKGROUND: With the overwhelming use of cementless femoral fixation for primary total hip arthroplasty in the United States, the associations of stem fixation on the risk of revision and mortality are poorly understood. We evaluated the relationship between femoral fixation and risk of revision and mortality in patients included in the American Joint Replacement Registry. METHODS: Elective, primary, unilateral total hip arthroplasties in the American Joint Replacement Registry, in patients over the age of 65 years were considered. In total, 9,612 patients with a cemented stem were exact matched 1:1 with patients who received a cementless stem based on age, gender, and the Charlson Comorbidity Index. Outcomes compared between the groups included need and reason for revision at 90 days and 1 year; in-hospital, 90-day, and 1-year mortality; and mortality after early revision. Covariates were used in linear regression analyses. RESULTS: Cemented fixation was associated with a 37% reduction in the risk of 90-day revision, and a reduction in the risk of revision for periprosthetic fracture of 87% at 90 days and 81% at 1 year. Cemented fixation was associated with increased 90-day and 1-year mortality (odds ratio [OR] 3.15, confidence interval [CI] 2.24-4.43 and OR 2.36, CI 1.86-3.01, respectively). Patients who underwent subsequent revision surgery within the first year exhibited the highest mortality risk (OR 3.23, CI 1.05-9.97). CONCLUSION: In this representative sample of the United States, 90-day revision for any reason and for periprosthetic fracture was significantly reduced in patients with a cemented stem. This benefit must be weighed against the association with increased mortality and with the high risk of mortality associated with early revision, which was more prevalent with cementless fixation.

Migration Patterns for Revision Total Hip Arthroplasty in the United States as Reported in the American Joint Replacement Registry.

BACKGROUND: Revision total hip arthroplasty (revTHA) is associated with higher rates of complications and greater costs than primary procedures. The aim of this study is to evaluate the effect of hospital size, teaching status, and indication for revTHA, on migration patterns in patients older than 65 years old. METHODS: All THAs and revTHAs reported to the American Joint Replacement Registry from 2012 to 2018 were included and merged with the Centers for Medicare and Medicaid Services database. Migration rate was defined as a patient's THA and revTHA procedures that were performed at separate institutions by different surgeons. Migratory patterns were recorded based on hospital size, teaching status, and indication for revTHA. Analyses were performed by statisticians. RESULTS: The number of linked procedures included was 11,906. Migration rates in revTHA due to infection were higher for small hospitals than large hospitals (46.6% vs 28.6%, P < .0001). Migration rates were higher comparing non-teaching with teaching hospitals (55% vs 34%, P < .0001). This difference was significant for periprosthetic fractures (70.6% vs 37.2%, P = .005), instability (56.5% vs 35.5%, P = .04), and mechanical complications (88.9% vs 34.7%, P < .05). Most patients migrated to medium or large hospitals rather than small hospitals (89% vs 11%, P < .0001) and to teaching rather than non-teaching institutions (82% vs 18%, P < .0001). CONCLUSION: Hospital size and teaching status significantly affected migration patterns for revTHA. Migration rates were significantly higher in small non-teaching hospitals in revTHA due to infection, periprosthetic fracture, instability, and mechanical complications. Over 80% of patients migrated to larger teaching hospitals.

Migration Patterns for Revision Total Knee Arthroplasty in the United States as Reported in the American Joint Replacement Registry.

BACKGROUND: Revision total knee arthroplasty (TKA) is associated with a higher complication rate and a greater cost when compared to primary TKA. Based on patient choice, referral, or patient transfers, revision TKAs are often performed in different institutions by different surgeons than the primary TKA. The aim of this study is to evaluate the effect of hospital size, teaching status, and revision indication on the migration patterns of failed primary TKA in patients 65 years of age and older. METHODS: All primary and revision TKAs reported to the American Joint Replacement Registry from January 2012 through March 2020 were included and merged with the Centers for Medicare and Medicaid Services database. Migration was defined as a patient having a primary TKA and revision TKA performed at separate institutions by different surgeons. RESULTS: In total, 9167 linked primary and revision TKAs were included in the analysis. Overall migration rates were significantly higher from small (<100 beds; P = .019), non-teaching institutions (P = .002) driven primarily by patients diagnosed with infection. Infection patients had significantly higher migration rates from small (46.8%, P < .001), non-teaching (43.5%, P < .001) institutions, while migration rates for other causes of revision were statistically similar. Most patients migrated to medium or large institutions (84.7%) for revision TKA rather than small institutions (15.3%, P < .001) and to teaching (78.3%) rather than non-teaching institutions (21.7%, P < .001). CONCLUSION: There is a diagnosis-dependent referral bias that affects the migration rates of infected primary TKA from small non-teaching institutions leading to a flow of more medically complex patients to medium and large teaching institutions for infected revision TKA.

Opioid Use in Robotic-Arm Assisted Total Knee Arthroplasty: A Comparison to Conventional Manual Total Knee Arthroplasty.

INTRODUCTION: Opioids are frequently prescribed in the postoperative management of total knee arthroplasty (TKA) with multiple factors influencing postoperative opioid use. Robotic-arm-assisted TKA (raTKA) was developed with the goal of improving alignment and outcomes while decreasing soft tissue injury. The purpose of this study was to compare postoperative opioid consumption in raTKA and conventional manual TKA (mTKA) cohorts. MATERIALS AND METHODS: A consecutive series of unilateral primary TKAs performed 1/1/16 to 12/31/17 were included. Patients with major procedures requiring opioids occurring within one year of TKA were excluded. A single-surgeon raTKA cohort of 127 patients (Group 1) was compared to a same-surgeon cohort of 119 mTKAs (Group 2) using the same cemented implant design and a two-surgeon cohort of 410 mTKA (Group 3). Groups were subdivided into opioid naïve (ON) and opioid exposed (OE). Length of hospitalization and postoperative opioid utilization up to one year were compared between groups and collectively without separating raTKA and mTKA. Statistical analysis included Chi-square, Student's t-test, and Wilcoxon rank sum tests. RESULTS: For both ON and OE patients, Group 1 demonstrated reduced inpatient mean daily oral morphine milligram equivalent (MME) compared to Group 3 (ON p=0.007; OE p=0.034), a shorter hospitalization compared to Group 2 (ON p=0.02; OE p=0.012), and fewer opioids prescribed at discharge compared to Group 2 (ON p=0.005; OE p=0.081) and Group 3 (ON p<0.001; OE p=0.036). No differences in opioid prescriptions were seen at three months or after. Regardless of surgical technique OE patients had higher inpatient opioid utilization (p<0.001) as well as cumulative outpatient prescription quantity (MME 1050 ON, 2660 OE) and duration (ON 0.5%; OE 28.3%) at one year (p<0.001). CONCLUSION: Less opioids were prescribed at discharge and used during hospitalization in raTKA compared to mTKA though no differences in opioid use were seen at further time points. Preoperative opioid use remains a dominant factor in postoperative opioid utilization regardless of TKA surgical technique.

Unrecognized Osteoporosis Is Common in Patients With a Well-Functioning Total Knee Arthroplasty.

BACKGROUND: Peri-prosthetic fractures after total knee arthroplasty (TKA) are associated with poorer outcomes and high costs. We hypothesize that osteoporosis is under-recognized in the TKA population. The purpose of this study is to report osteoporosis prevalence in a healthy cohort of patients with well-functioning TKA and to compare prevalence between males and females. METHODS: This study is a cross-sectional study of 30 adults (15 males/15 females) aged 59-80 years without known bone health issues who volunteered to undergo routine dual-energy X-ray absorptiometry 2-5 years (average 3.2 ± 0.8) after primary unilateral TKA. These data plus clinical risk factors were used to estimate fracture risk via the Fracture Risk Assessment Tool and skeletal status (normal, osteopenic, osteoporotic) was determined based on the World Health Organization definition. The National Osteoporosis Foundation criteria for treatment were applied to all patients. RESULTS: Six of 30 (20%) patients had T-score ≤ -2.5. Eighteen of 30 (60%) patients had T-score between -1 and -2.5 and 6 (20%) patients had T-score ≥ -1. Five patients with normal or osteopenic bone mineral density (BMD) had occult vertebral fractures. Eleven of 30 (36.7%) patients met National Osteoporosis Foundation criteria for pharmacologic treatment. CONCLUSION: The prevalence of occult osteoporosis meeting treatment guidelines after TKA is substantial in this sample (36.7%). BMD and osteoporosis prevalence are similar between men and women. This underappreciated prevalence of osteoporosis may contribute to peri-prosthetic fracture risk. Arthroplasty surgeons and bone health specialists must be aware of post-operative changes in bone density. These data support the further study of post-operative osteoporosis and consideration of routine BMD screening after TKA. LEVEL OF EVIDENCE: III.

Trends in the Use of High-Viscosity Cement in Patients Undergoing Primary Total Knee Arthroplasty in the United States.

BACKGROUND: Aseptic loosening remains the most common mode of failure following total knee arthroplasty (TKA). Although the risk of loosening is multifactorial, recent studies reported early failure via debonding at the tibial implant-cement interface and a potential association with high viscosity cement (HVC). The purpose of this study is to determine the type of cement used by surgeons performing elective, primary TKA in the United States. METHODS: A retrospective cohort study was performed using data reported to the American Joint Replacement Registry from 2012 to 2017. The primary variable assessed was the type of cement used in each primary TKA, categorized as HVC, medium viscosity cement, or low viscosity cement based on the manufacturer's specifications. The use of antibiotic-impregnated cement was also assessed. RESULTS: A total of 554,935 primary TKA procedures were reviewed over the 7-year period. The use of HVC steadily increased from 46.0% of TKAs in 2012 to 61.3% of TKAs in 2017. Conversely, the use of low viscosity cement decreased in use from 47.9% of TKAs in 2012 to 30.9% in 2017. The percentage of TKAs performed using antibiotic-impregnated cement also decreased from 44.2% in 2012 to 34.5% in 2017. CONCLUSION: This study demonstrates that the percentage of TKAs performed using HVC has continued to increase over the most recent 7 years for which the American Joint Replacement Registry has data. The risk of aseptic loosening is clearly multifactorial, but close monitoring is necessary to determine whether this change in surgeon preference will affect component survivorship.

Robotic-Assisted Total Hip Arthroplasty: Outcomes at Minimum Two-Year Follow-Up.

BACKGROUND: Component malposition in total hip arthroplasty (THA) contributes to instability and early failure. Robotic-assisted total hip arthroplasty (rTHA) utilizes CT-based planning with haptically-guided bone preparation and implant insertion to optimize component position accuracy. This study compared acetabular component position and postoperative complications following manual THA (mTHA) with rTHA. MATERIALS AND METHODS: Consecutive primary THAs performed by one surgeon at three intervals were analyzed in this retrospective cohort study: the initial 100 consecutive manual THAs (mTHA) in clinical practice (year 2000), the last consecutive 100 mTHA before rTHA introduction (year 2011), and the first consecutive 100 rTHA (year 2012). Acetabular abduction (AAB) and anteversion (AAV) angles were measured using validated software. The Lewinnek safe zone was used to define accuracy (AAB 40°±10° and AAV 15°±10°). Comparisons included operative time, estimated blood loss (EBL), infection rate, and dislocation rate. RESULTS: The rate of acetabular component placement within Lewinnek safe zone was the highest in the rTHA cohort (77%), followed by late mTHA (45%) and early mTHA (30%) (p<0.001). Robotic-assisted THA resulted in an additional 71% improvement in accuracy in the first year of use (p<0.001). Dislocation rate was 5% with early mTHA, 3% in the late mTHA cohort, and 0% in the rTHA cohort within the first two years postoperatively. There were no statistically significant differences in the rate of infection between groups. CONCLUSION: Robotic-assisted THA improved acetabular component accuracy and reduced dislocation rates when compared with mTHA. Further study is needed to determine if similar improvements will be noted in larger multicenter studies using alternative surgical approaches.

Improved Functional Outcomes with Robotic Compared with Manual Total Hip Arthroplasty.

INTRODUCTION: Functional outcome following total hip arthroplasty (THA) is affected by accurate component positioning and restoration of hip biomechanics. Robotic-assisted THA (rTHA) has been shown to improve accuracy of component positioning, but its impact on functional outcomes has not been demonstrated. The purpose of this study was to compare: 1) operative time; 2) estimated blood loss; 3) postoperative complications; and 4) patient-reported outcome measures (PROMs) between patients who either underwent rTHA or manual THA (mTHA). MATERIALS AND METHODS: In this retrospective cohort study, a single-center database was used to identify all patients who underwent primary THA since introduction of rTHA at a large academic medical center. Surgical factors including operative time and estimated blood loss as well as postoperative complications were recorded. Validated PROMs following rTHA (n = 100) were compared with consecutive mTHA cases (n = 100) performed by the same fellowship-trained surgeon at a minimum one-year follow-up (24 ± 6 months). PROMs included the Short-Form 12 Health Survey (SF-12), UCLA activity score (UCLA), Western Ontario and McMaster (WOMAC) Osteoarthritis Index, and modified Harris Hip Score (mHHS). A categorical analysis was performed to determine differences in proportions of patients with mHHS scores of 90 to 100, 80 to 89, 70 to 79, and < 70 points between the two groups. Chi-square and two-tailed t-tests were used to compare categorical and continuous data between cohorts. RESULTS: Mean operative time was nine minutes longer for the rTHA group compared with the mTHA group (131 ± 23 min vs. 122 ± 29 min, respectively, p = 0.012). Estimated intraoperative blood loss was significantly reduced for the rTHA group when compared to the mTHA group (374 ± 133 mL vs. 423 ± 186 mL, p = 0.035), and there was no difference in overall complication rates between the two groups (p = 0.101). Robotic-assisted THA demonstrated significantly higher mean postoperative mHHS (92.1 ± 10.5 vs. 86.1 ± 16.2, p = 0.002) and mean UCLA scores (6.3 ± 1.8 vs. 5.8 ± 1.7, p = 0.033) compared with mTHA. The difference between pre- and postoperative mHHS scores was statistically significant when comparing rTHA with mTHA (43.0 ± 18.8 vs. 37.4 ± 18.3, p = 0.035). There were no significant differences in SF-12 or WOMAC scores. There was a significantly higher proportion of patients with mHHS scores between 90 to 100 points (75% vs. 61%, p = 0.034) and a lower percentage with scores < 70 points (6% vs. 19%, p = 0.005) in the rTHA cohort compared with the mTHA cohort. DISCUSSION: The rTHA cohort demonstrated significantly higher mean postoperative UCLA scores, higher mean postoperative mHHS scores, and a greater percentage of patients with mHHS of 90 to 100 points compared with mTHA at a minimum one-year follow-up. To our knowledge, this is the first study to demonstrate that robotic-assisted THA leads to improved patient-reported outcomes. The observed improvement in functional outcomes following rTHA is encouraging and warrants additional multi-center studies to determine if these advantages are maintained at longer follow-up intervals.

Dislocation Rates of Primary Total Hip Arthroplasty in Patients With Prior Lumbar Spine Fusion and Lumbar Degenerative Disk Disease With and Without Utilization of Dual Mobility Cups: An American Joint Replacement Registry Study.

INTRODUCTION: Patients undergoing primary total hip arthroplasty (THA) with a previous history of lumbar spine fusion (LSF) are at increased risk of dislocation. The purpose of this study was to compare the 90-day and 1-year dislocation rates of patients with LSF or lumbar degenerative disk disease who underwent primary THA with and without dual mobility (DM) constructs. METHODS: An American Joint Replacement Registry data set of patients aged 65 years and older undergoing primary THA with minimum 1-year follow-up with a history of prior LSF or a diagnosis of lumbar degenerative disk disease was created. DM status was identified, and dislocation and all-cause revision at 90 days and 1 year were assessed. RESULTS: A total of 15,572 patients met study criteria. The overall dislocation rates for the non-DM and DM groups were 1.17% and 0.68%, respectively, at 90 days, and 1.68% and 0.91%, respectively, at 1 year ( P = 0.005). The odds of 90-day (OR = 0.578, [ P = 0.0328]) and 1-year (OR = 0.534, [ P = 0.0044]) dislocation were significantly less with DM constructs, compared with non-DM constructs. No statistically significant difference was observed in revision rates between groups. DISCUSSION: This large registry-based study identified a reduced risk of dislocation in patients at risk for spinal stiffness when a DM compared with non-DM construct was used in primary THA at 90-day and 1-year follow-up intervals. Our data support the use of DM constructs in high-risk patients with stiff spines and altered spinopelvic mobility as a promising option to mitigate the risk of postoperative hip instability after primary THA. LEVELS OF EVIDENCE: Level III. Therapeutic retrospective cohort.

Low rates of heterotopic ossification after resurfacing hip arthroplasty with use of prophylactic radiotherapy in select patients.

Recent reports have noted higher rates of heterotopic ossification (HO) with surface replacement arthroplasty (SRA) than with traditional total hip arthroplasty in the absence of postoperative HO prophylaxis. This study reports rates and grades of HO in 44 SRA patients with at least 1 year of follow-up. Heterotopic ossification prophylaxis was used in 32 (73%) of 44 cases. Heterotopic ossification prophylaxis consisted of radiotherapy (22/32), nonsteroidal anti-inflammatory drugs (8/32), or both (2/32). One case of clinically significant HO was documented in the no-prophylaxis group. This strategy of selective HO prophylaxis in patients felt by orthopedic surgeons to be at high risk of HO resulted in low rates of clinically relevant HO after SRA (1/44, 2.3%). Further study is needed to establish optimal selection criteria for HO prophylaxis after SRA.

Comparative Cost Analysis of Robotic-Assisted and Jig-Based Manual Primary Total Knee Arthroplasty.

Excellent durability with traditional jig-based manual total knee arthroplasty (mTKA) has been noted, but substantial rates of dissatisfaction remain. Robotic-assisted TKA (raTKA) was introduced to improve clinical outcomes, but associated costs have not been well studied. The purpose of our study is to compare 90-day episode-of-care (EOC) costs for mTKA and raTKA. A retrospective review of an institutional database from 4/2015 to 9/2017 identified consecutive mTKAs and raTKAs using a single implant system performed by one surgeon. The raTKA platform became available at our institution in October 2016. Prior to this date, all TKAs were performed with mTKA technique. After this date, all TKAs were performed using robotic-assistance without exception. Sequential cases were included for both mTKA and raTKA with no patients excluded. Clinical and financial data were obtained from medical and billing records. Ninety-day EOC costs were compared. Statistical analysis was performed by departmental statistician. One hundred and thirty nine mTKAs and 147 raTKAs were identified. No significant differences in patient characteristics were noted. Total intraoperative costs were higher ($10,295.17 vs. 9,998.78, respectively, p < 0.001) and inpatient costs were lower ($3,893.90 vs. 5,587.40, respectively, p < 0.001) comparing raTKA and mTKA. Length of stay (LOS) was reduced 25% (1.2 vs. 1.6 days, respectively, p < 0.0001) and prescribed opioids were reduced 57% (984.2 versus 2240.4 morphine milligram equivalents, respectively, p < 0.0001) comparing raTKA with mTKA. Ninety-day EOC costs were $2,090.70 lower for raTKA compared with mTKA ($15,629.94 vs. 17,720.64, respectively; p < 0.001). The higher intraoperative costs associated with raTKA were offset by greater savings in postoperative costs for the 90-day EOC compared with mTKA. Higher intraoperative costs were driven by the cost of the robot, maintenance fees, and robot-specific disposables. Cost savings with raTKA were primarily driven by reduced instrument pan reprocessing fees, shorter LOS, and reduced prescribed opioids compared with mTKA technique. raTKA demonstrated improved value compared with mTKA based on significantly lower average 90-day EOC costs and superior quality exemplified by reduced LOS, less postoperative opioid requirements, and reduced postdischarge resource utilization.

The Influence of Femoral Fixation on Mortality and Revision After Hip Arthroplasty in Femoral Neck Fractures in Patients Older Than 65 Years. A Matched Cohort Analysis From the American Joint Replacement Registry.

INTRODUCTION: In the United States, most hip arthroplasties for femoral neck fractures are done with a noncemented stem despite worldwide registry data suggesting that cemented fixation has improved long-term survivorship in patients older than 65 years. We, therefore, evaluated the effect of femoral fixation on the risk of revision, revision for periprosthetic fracture (PPFx), and mortality in patients undergoing hip arthroplasty for femoral neck fractures. METHODS: Seventeen thousand one hundred thirty-eight cases of cemented femoral stems were exactly matched to noncemented fixation cases in a 1:1 fashion based on age, sex, and Charlson Comorbidity Index as reported in the American Joint Replacement Registry. Outcome variables included revision for PPFx, all-cause revision within 1 year and 90 days, and in-hospital mortality at 90 days and 1 year. The primary independent variable was femoral fixation (cemented and noncemented), and covariates included race (black, white, and others), ethnicity (Hispanic and non-Hispanic), hospital teaching status (minor, major, and nonteaching), and hospital size (number of beds: 1 to 99, 100 to 399, and ≥400). Chi square tests and multivariable logistic regression models were used for statistical analysis. RESULTS: Hip arthroplasty with a cemented stem was associated with a 30% reduction in all-cause revision at 90 days (odds ratio [OR]:0.692, confidence interval [CI]:0.558 to 0.86), a 29% reduction in revision at 1 year (OR:0.709, CI:0.589 to 0.854), and an 86% reduction in revision for PPFx (OR:0.144, CI:0.07 to 0.294). However, cemented stem fixation was associated with increased odds of in-hospital (OR: 2.232 CI: 1.644 to 3.3031), 90-day, and 1-year (OR:1.23, CI:1.135 to 1.339; and OR:1.168, CI:1.091 to 1.25, respectively) mortality. DICUSSION: In this exact match study, cemented stem fixation for femoral neck fracture was associated with a markedly reduced risk of revision for PPFx and for all-cause revision. This must be weighed against the associated increased risk in mortality, which warrants additional investigation.

Is American Joint Replacement Registry Data Representative of National Data? A Comparative Analysis.

INTRODUCTION: The American Academy of Orthopaedic Surgeons American Joint Replacement Registry (AJRR) is the largest registry of total hip and knee arthroplasty (THA and TKA) procedures performed in the United States. The purpose of this study was to examine whether AJRR data are representative of the national experience with hip and knee arthroplasty as represented in the National (Nationwide) Inpatient Sample (NIS). METHODS: All patients undergoing a THA or TKA procedure between 2012 to 2018 (AJRR) and 2012 to 2016 (NIS) were identified. Cohen d effect sizes were computed to ascertain the magnitude of differences in demographics, hospital volume (in 50 patient increments), and geographic characteristics between the AJRR and NIS databases. RESULTS: The study included (NIS: 2,316,345 versus AJRR: 557,684) primary THA and (NIS: 3,417,700 versus AJRR: 809,494) TKA procedures. The magnitude of distribution, as determined by the Cohen d effect size, showed that the proportions of AJRR and NIS patients were similar based on overall sex (THAs [d = 0.03] and TKAs [d = 0.02]) and age (THAs [d = 0.17] and TKAs [d = 0.12]). Similarly, only small differences (d = 0.34 or less) were identified between databases considering hospital volume and geography. The AJRR was underrepresented in Southern regions and hospitals with low procedure volume and overrepresented in Northern hospitals and those with larger volume. Both the NIS and the AJRR followed a similar overall trend, with most procedures performed at hospitals with <50 cases per year. DISCUSSION: Distributions across hospital volume, age, and geography were proportionally similar between the AJRR and NIS databases, supporting the generalizability of AJRR findings to the larger US cohort.

Relative Clinical Outcomes Comparing Manual and Robotic-Assisted Total Knee Arthroplasty at Minimum 1-Year Follow-up.

Background: Total knee arthroplasty (TKA) demonstrates excellent durability using jig-based manual techniques (manual TKA [mTKA]), but significant rates of dissatisfaction remain. Modifications of mTKA techniques and TKA implant designs to improve outcomes have had minimal success. Studies comparing relative outcomes of mTKA and robotic-assisted TKA (raTKA) are limited. Purpose: This study sought to compare outcomes of mTKA and raTKA in patients at a single institution. Methods: We retrospectively reviewed all primary TKAs performed by 1 surgeon from 2015 to 2017. In all, 139 consecutive mTKAs (2015-2016) and 148 consecutive raTKAs (2016-2017) were included. No cases were excluded. Patient demographics, complications, readmission rates, and clinical and patient-reported outcomes were compared at a minimum of 1-year follow-up. A post hoc student t test and Pearson χ2 test were used for continuous and categorical data. Results: We found that mTKA patients compared with raTKA patients required significantly longer length of stay (LOS) (1.73 vs 1.18 days, respectively), greater morphine milligram equivalents consumption (89.6 vs 65.2, respectively), and increased physical therapy (PT) visits (13.0 vs 11.0, respectively) with increased 30-day readmission rates (4.3 vs 0.7%, respectively) that approached significance. Knee Injury and Osteoarthritis Outcome Score for Joint Replacement and the University of California at Los Angeles activity score did not differ significantly comparing raTKA with mTKA patients at 1 year. There were no differences in complication rates. Conclusion: Significant early clinical benefits were noted with raTKA, including lower opioid requirements, shorter LOS, and fewer PT visits when compared with mTKA. A reduction in 30-day readmission rates was noted with raTKA that was not significant. Excellent clinical results with similar patient-reported outcomes were noted in both groups at 1-year follow-up. Further prospective investigations at longer follow-up intervals comparing these techniques are warranted.

Large-head metal-on-metal total hip arthroplasty using the Durom acetabular component at minimum 1-year interval.

Large-head metal-on-metal total hip arthroplasty represents novel technology, and outcome data are lacking. We prospectively compared the performance of a nonmodular metal-on-metal acetabular component (Durom; Zimmer, Warsaw, IN) with a modular titanium component (Trilogy, Zimmer). All Durom components placed at our institution with minimum 1-year follow up (n = 63) were compared with an age- and sex-matched Trilogy control group (n = 100). Failure defined as revision or persistent moderate/severe groin pain was significantly higher for the Durom (11.1%) compared with the Trilogy group (0%) (P = .002). Although all acetabular components in both groups appeared radiographically stable, no significant bone ingrowth was noted at the time of Durom revisions. We could not identify any patient/surgical-related factors predictive of failure. Further study is needed to determine the scientific basis for these observations.

Prospective analysis of a novel long-acting oral opioid analgesic regimen for pain control after total hip and knee arthroplasty.

Parenteral opioid use after total knee (TKA) and hip (THA) arthroplasty often results in substantial functional interference and side effects. This prospective study compared use of traditional intravenous patient-controlled analgesia (IV PCA) with a novel oral regimen after TKA and THA. Sixty-two patients received IV PCA and 62 received scheduled long-acting and, as needed, short-acting oral opioids postoperatively. Surveys and chart audits documented functional interference, pain scores, opioid-related side effects, and opioid consumption. Patients who received the oral regimen had significantly less opioid consumption (P < .05) and experienced less functional interference (P < .05) than the IV PCA group. Both groups had similar pain scores and incidence of opioid side effects. This study demonstrates some significant advantages of an oral analgesic regimen compared with IV PCA after TKA and THA.