Gremlin 1 identifies a skeletal stem cell with bone, cartilage, and reticular stromal potential.

The stem cells that maintain and repair the postnatal skeleton remain undefined. One model suggests that perisinusoidal mesenchymal stem cells (MSCs) give rise to osteoblasts, chondrocytes, marrow stromal cells, and adipocytes, although the existence of these cells has not been proven through fate-mapping experiments. We demonstrate here that expression of the bone morphogenetic protein (BMP) antagonist gremlin 1 defines a population of osteochondroreticular (OCR) stem cells in the bone marrow. OCR stem cells self-renew and generate osteoblasts, chondrocytes, and reticular marrow stromal cells, but not adipocytes. OCR stem cells are concentrated within the metaphysis of long bones not in the perisinusoidal space and are needed for bone development, bone remodeling, and fracture repair. Grem1 expression also identifies intestinal reticular stem cells (iRSCs) that are cells of origin for the periepithelial intestinal mesenchymal sheath. Grem1 expression identifies distinct connective tissue stem cells in both the bone (OCR stem cells) and the intestine (iRSCs).

Methionine oxidation activates pyruvate kinase M2 to promote pancreatic cancer metastasis.

Cancer mortality is primarily a consequence of its metastatic spread. Here, we report that methionine sulfoxide reductase A (MSRA), which can reduce oxidized methionine residues, acts as a suppressor of pancreatic ductal adenocarcinoma (PDA) metastasis. MSRA expression is decreased in the metastatic tumors of PDA patients, whereas MSRA loss in primary PDA cells promotes migration and invasion. Chemoproteomic profiling of pancreatic organoids revealed that MSRA loss results in the selective oxidation of a methionine residue (M239) in pyruvate kinase M2 (PKM2). Moreover, M239 oxidation sustains PKM2 in an active tetrameric state to promote respiration, migration, and metastasis, whereas pharmacological activation of PKM2 increases cell migration and metastasis in vivo. These results demonstrate that methionine residues can act as reversible redox switches governing distinct signaling outcomes and that the MSRA-PKM2 axis serves as a regulatory nexus between redox biology and cancer metabolism to control tumor metastasis.

Opposing roles of hepatic stellate cell subpopulations in hepatocarcinogenesis.

Hepatocellular carcinoma (HCC), the fourth leading cause of cancer mortality worldwide, develops almost exclusively in patients with chronic liver disease and advanced fibrosis1,2. Here we interrogated functions of hepatic stellate cells (HSCs), the main source of liver fibroblasts3, during hepatocarcinogenesis. Genetic depletion, activation or inhibition of HSCs in mouse models of HCC revealed their overall tumour-promoting role. HSCs were enriched in the preneoplastic environment, where they closely interacted with hepatocytes and modulated hepatocarcinogenesis by regulating hepatocyte proliferation and death. Analyses of mouse and human HSC subpopulations by single-cell RNA sequencing together with genetic ablation of subpopulation-enriched mediators revealed dual functions of HSCs in hepatocarcinogenesis. Hepatocyte growth factor, enriched in quiescent and cytokine-producing HSCs, protected against hepatocyte death and HCC development. By contrast, type I collagen, enriched in activated myofibroblastic HSCs, promoted proliferation and tumour development through increased stiffness and TAZ activation in pretumoural hepatocytes and through activation of discoidin domain receptor 1 in established tumours. An increased HSC imbalance between cytokine-producing HSCs and myofibroblastic HSCs during liver disease progression was associated with increased HCC risk in patients. In summary, the dynamic shift in HSC subpopulations and their mediators during chronic liver disease is associated with a switch from HCC protection to HCC promotion.

Experimentally Induced Peripheral Venous Congestion Exacerbates Inflammation, Oxidative Stress, and Neurohormonal and Endothelial Cell Activation in Patients With Systolic Heart Failure.

BACKGROUND: Venous congestion (VC) is a hallmark of symptomatic heart failure (HF) requiring hospitalization; however, its role in the pathogenesis of HF progression remains unclear. We investigated whether peripheral VC exacerbates inflammation, oxidative stress and neurohormonal and endothelial cell (EC) activation in patients with HF with reduced ejection fraction (HFrEF). METHODS AND RESULTS: Two matched groups of patients with HFrEF and with no peripheral VC vs without recent HF hospitalization were studied. We modeled peripheral VC by inflating a cuff around the dominant arm, targeting ∼ 30 mmHg increase in venous pressure (venous stress test [VST]). Blood and ECs were sampled before and after 90 minutes of VST. We studied 44 patients (age 53 ± 12 years, 32% female). Circulating endothelin-1, tumor necrosis factor-α, interleukin-6, isoprostane, angiotensin II (ang-2), angiopoietin-2, vascular cell adhesion molecule-1, and CD146 significantly increased after the VST. Enhanced endothelin-1 and angiopoietin-2 responses to the VST were present in patients with vs without recent hospitalization and were prospectively associated with incident HF-related events; 6698 messenger ribonucleic acid (mRNA probe sets were differentially expressed in ECs after VST. CONCLUSIONS: Experimental VC exacerbates inflammation, oxidative stress, neurohormonal and EC activation and promotes unfavorable transcriptome remodeling in ECs of patients with HFrEF. A distinct biological sensitivity to VC appears to be associated with high risk for HF progression.

Impact of opioid dependence on outcomes following total shoulder arthroplasty.

INTRODUCTION: The opioid epidemic is a well-established problem encountered in orthopedic surgery in the United States. Evidence in lower extremity total joint arthroplasty and spine surgery suggests a link between chronic opioid use and increased expense and rates of surgical complications. The purpose of this study was to study the impact of opioid dependence (OD) on the short-term outcomes following primary total shoulder arthroplasty (TSA). METHODS: A total of 58,975 patients undergoing primary anatomic and reverse TSA were identified using the National Readmission Database from 2015 to 2019. Preoperative opioid dependence status was used to divide patients into 2 cohorts, with 2089 patients being chronic opioid users or having opioid use disorders. Preoperative demographic and comorbidity data, postoperative outcomes, cost of admission, total hospital length of stay (LOS), and discharge status were compared between the 2 groups. Multivariate analysis was conducted to control for the influence of independent risk factors other than OD on postoperative outcomes. RESULTS: Compared to nonopioid-dependent patients, OD patients undergoing TSA had higher odds of postoperative complications including any complications within 180 days (odds ratio [OR] 1.4, 95% confidence interval [CI] 1.3-1.7), readmission within 180 days (OR 1.2, 95% CI 1.1-1.5), revision within 180 days (OR 1.7, 95% CI 1.4-2.1), dislocation (OR 1.9, 95% CI 1.3-2.9), bleeding (OR 3.7, 95% CI 1.5-9.4), and gastrointestinal complication (OR 14, 95% CI 4.3-48). Total cost ($20,741 vs. $19,643), LOS (1.8 ± 1.8 days vs. 1.6 ± 1.7 days), and likelihood for discharge to another facility or home with home health care (18 vs. 16% and 23% vs. 21%, respectively) were higher in patients with OD. CONCLUSION: Preoperative opioid dependence was associated with higher odds of postoperative complications, rates of readmission and revision, costs, and health care utilization following TSA. Efforts focused on mitigating this modifiable behavioral risk factor may lead to better outcomes, lower complications, and decreased associated costs.

Stratification of the minimal clinically important difference, substantial clinical benefit, and patient acceptable symptomatic state after total shoulder arthroplasty by implant type, preoperative diagnosis, and sex.

BACKGROUND: Clinical significance, as opposed to statistical significance, has increasingly been utilized to evaluate outcomes after total shoulder arthroplasty (TSA). The purpose of this study was to identify thresholds of the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS) for TSA outcome metrics and determine if these thresholds are influenced by prosthesis type (anatomic or reverse TSA), sex, or preoperative diagnosis. METHODS: A prospectively collected international multicenter database inclusive of 38 surgeons was queried for patients receiving a primary aTSA or rTSA between 2003 and 2021. Prospectively, outcome metrics including ASES, shoulder function score (SFS), SST, UCLA, Constant, VAS Pain, shoulder arthroplasty smart (SAS) score, forward flexion, abduction, external rotation, and internal rotation was recorded preoperatively and at each follow-up. A patient satisfaction question was administered at each follow-up. Anchor-based MCID, SCB, and PASS were calculated as defined previously overall and according to implant type, preoperative diagnosis, and sex. The percentage of patients achieving thresholds was also quantified. RESULTS: A total of 5851 total shoulder arthroplasties (TSAs) including aTSA (n = 2236) and rTSA (n = 3615) were included in the study cohort. The following were identified as MCID thresholds for the overall (aTSA + rTSA irrespective of diagnosis or sex) cohort: VAS Pain (-1.5), SFS (1.2), SST (2.1), Constant (7.2), ASES (13.9), UCLA (8.2), SPADI (-21.5), and SAS (7.3), Abduction (13°), Forward elevation (16°), External rotation (4°), Internal rotation score (0.2). SCB thresholds for the overall cohort were: VAS Pain (-3.3), SFS (2.9), SST 3.8), Constant (18.9), ASES (33.1), UCLA (12.3), SPADI (-44.7), and SAS (18.2), Abduction (30°), Forward elevation (31°), External rotation (12°), Internal rotation score (0.9). PASS thresholds for the overall cohort were: VAS Pain (0.8), SFS (7.3), SST (9.2), Constant (64.2), ASES (79.5), UCLA (29.5), SPADI (24.7), and SAS (72.5), Abduction (104°), Forward elevation (130°), External rotation (30°), Internal rotation score (3.2). MCID, SCB, and PASS thresholds varied depending on preoperative diagnosis and sex. CONCLUSION: MCID, SCB, and PASS thresholds vary depending on implant type, preoperative diagnosis, and sex. A comprehensive understanding of these differences as well as identification of clinically relevant thresholds for legacy and novel metrics is essential to assist surgeons in evaluating their patient's outcomes, interpreting the literature, and counseling their patients preoperatively regarding expectations for improvement. Given that PASS thresholds are fragile and vary greatly depending on cohort variability, caution should be exercised in conflating them across different studies.

Delayed elective total shoulder arthroplasty: causes and eventual outcomes.

PURPOSE: The purpose of this study is to identify risk factors for delays in planned total shoulder arthroplasty (TSA) and determine the perioperative outcomes of TSAs that experienced a delay. METHODS: The American College of Surgeons National Quality Improvement Program (NSQIP) database was queried from 2006 to 2019 for primary TSA. Delayed TSA was defined as surgery that occurred greater than one day after hospital admission. Patient demographics, comorbidities, and post-operative complications were collected and compared; the incidence of delayed TSA was analyzed. RESULTS: The delayed patients were older, had a higher BMI, a higher rate of recent prior major surgery, and more comorbidities. Delayed patients had higher rates of postoperative complications, return to the OR, and 30-day readmission. Between 2006 and 2019, the rate of delayed TSA decreased. CONCLUSION: Surgeons should take care to ensure that patients with comorbidities undergo thorough preoperative clearance to prevent same-day cancellations and postoperative complications.

MC4R-dependent suppression of appetite by bone-derived lipocalin 2.

Bone has recently emerged as a pleiotropic endocrine organ that secretes at least two hormones, FGF23 and osteocalcin, which regulate kidney function and glucose homeostasis, respectively. These findings have raised the question of whether other bone-derived hormones exist and what their potential functions are. Here we identify, through molecular and genetic analyses in mice, lipocalin 2 (LCN2) as an osteoblast-enriched, secreted protein. Loss- and gain-of-function experiments in mice demonstrate that osteoblast-derived LCN2 maintains glucose homeostasis by inducing insulin secretion and improves glucose tolerance and insulin sensitivity. In addition, osteoblast-derived LCN2 inhibits food intake. LCN2 crosses the blood-brain barrier, binds to the melanocortin 4 receptor (MC4R) in the paraventricular and ventromedial neurons of the hypothalamus and activates an MC4R-dependent anorexigenic (appetite-suppressing) pathway. These results identify LCN2 as a bone-derived hormone with metabolic regulatory effects, which suppresses appetite in a MC4R-dependent manner, and show that the control of appetite is an endocrine function of bone.

Corrigendum: MC4R-dependent suppression of appetite by bone-derived lipocalin 2.

This corrects the article DOI: 10.1038/nature21697.

Patient outcomes after revision total shoulder arthroplasty in an inpatient vs. outpatient setting.

BACKGROUND: Total shoulder arthroplasty (TSA) is becoming an increasingly common surgical procedure for numerous shoulder conditions. The incidence of revision TSA is increasing because of the increase in primary TSA and the increased utilization of TSA in younger patients. Conducting revision TSA as an outpatient procedure would be beneficial in limiting expenditure and resource allocation but must show a similar complication profile compared to inpatient revision TSA in order to justify its clinical value. The purpose of this study is to compare the outcomes of outpatient revision TSA to inpatient revision TSA and outpatient primary TSA. METHODS: The American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database was queried from 2010-2019 to identify all patients who underwent revision TSA (n = 1456) in either an inpatient or outpatient setting, as well as patients who underwent primary TSA in an outpatient setting (n = 2630). Relevant demographic characteristics were compared between the outpatient revision group and both the inpatient revision and outpatient primary groups. Postoperative complications, readmission, and reoperation rates were also compared between the groups. RESULTS: Patients undergoing inpatient revision TSA exhibited increased rates of preoperative hypertension (P = .013) and had increased prevalence of severe American Society of Anesthesiologists classification (P = .021) compared to patients undergoing outpatient revision TSA. Patients undergoing outpatient revision TSA were significantly more likely to experience complications (P < .001), have longer surgical times (P < .001), and undergo readmission (P = .006) and reoperation (P = .049) compared to patients undergoing outpatient primary TSA. There was no significant increase in rates of overall complication, readmission, or reoperation between patients undergoing revision TSA in an outpatient vs. an inpatient setting. CONCLUSION: Outpatient revision TSA has higher complication rates, readmission, and reoperation rates compared to outpatient primary TSA, similar to previous findings when comparing revision and primary TSA done as an inpatient. However, there was no increased risk of complications, readmission, or reoperation for outpatient revision TSA compared to inpatient revision TSA. Outpatient revision TSA should be considered by orthopedic surgeons in patients who are medically healthy to undergo the procedure as an outpatient surgery.

How using body mass index cutoffs to determine eligibility for total shoulder arthroplasty affects health care disparities.

BACKGROUND: The prevalence of obesity in the United States is continuously rising and is associated with increased morbidity, mortality, and health care costs. Body mass index (BMI) has been used as a risk stratification and counseling tool for patients undergoing total joint arthroplasty in an effort to focus on outcome-driven care. Although the use of BMI cutoffs may have benefits in minimizing complications when selecting patients for total shoulder arthroplasty (TSA), it may impact access to care for some patient populations and further increase disparities. The purpose of this study is to determine the implications of using BMI cutoffs on the eligibility for TSA among different ethnic and gender patient populations. METHODS: The American College of Surgeons National Surgical Quality Improvement Program database was queried to identify 20,872 patients who underwent anatomic and reverse TSA between 2015 and 2019. Patient demographics, including age, sex, race and ethnicity, and BMI, were compared between eligible and ineligible patients based on BMI for 5 cutoff values: 30, 35, 40, 45, and 50 kg/m2. RESULTS: Of the total patient population studied, the mean age was 69 years, 55% were female, and the mean BMI was 31 kg/m2. For all BMI subgroups, there were more ineligible than eligible patients who were female or Black (P < .001). The relative rate of eligibility for Black patients was lower in each BMI cutoff group, whereas the relative rate of eligibility for White and Asian patients was higher for each group. There were more eligible than ineligible Asian patients for BMI cutoffs of 30 and 35 kg/m2 (both P < .001), and there were no differences in eligibility and ineligibility in Hispanic patients (P > .05). Furthermore, White patients were more eligible than ineligible for all BMI cutoff groups (P < .001). CONCLUSIONS: Enforcing BMI cutoffs for access to TSA may limit the procedure for female or Black patients for all BMI cutoffs, thus furthering the health care disparities these populations already face. However, there are more eligible than ineligible White patients for all BMI cutoff groups, which indicates a disparity in the access to TSA based on sex and race. Physicians may inadvertently increase health care disparities observed in TSA if they use BMI as the sole risk stratification tool for patients, even though BMI has been known to increase complications after TSA. Moreover, orthopedic surgeons should only use BMI as one of many factors in a more holistic process when determining if a patient should undergo TSA.

Aseptic glenoid baseplate loosening after reverse total shoulder arthroplasty with a single prosthesis.

BACKGROUND: Early reverse total shoulder arthroplasty (rTSA) designs had high failure rates, mainly from loosening of the glenoid baseplate. The purpose of this study was to determine the incidence of aseptic glenoid baseplate loosening after primary rTSA using a contemporary medialized glenoid-lateralized humerus system and identify significant risk factors associated with loosening. METHODS: A total of 7162 patients underwent primary rTSA with a single-platform rTSA system between April 2007 and August 2021; of these primary rTSA patients, 3127 with a minimum 2-year follow-up period were identified. Patients with aseptic glenoid baseplate loosening were compared with all other primary rTSA patients without loosening. Univariate and multivariate analyses were performed to compare these cohorts and identify the demographic characteristics, comorbidities, operative parameters, and implant characteristics associated aseptic glenoid loosening after rTSA. Odds ratios (ORs) were calculated for each significant risk factor and for multiple combinations of risk factors. RESULTS: Irrespective of minimum follow-up, 53 of 7162 primary rTSA shoulders (31 female and 22 male shoulders) experienced aseptic glenoid loosening, for an overall rate of 0.74%. At latest (2-year minimum) follow-up, 30 of 3127 patients experienced aseptic glenoid loosening and showed significantly lower clinical scores, function, and active range of motion and higher pain scores than patients without loosening. Univariate analysis identified rheumatoid arthritis (P = .029; OR, 2.74) and diabetes (P = .028; OR, 1.84) as significant risk factors for aseptic glenoid loosening after rTSA, and multivariate analysis identified Walch glenoid types B2 (P = .002; OR, 4.513) and B3 (P = .002; OR, 14.804), use of expanded lateralized glenospheres (P = .025; OR, 2.57), and use of augmented baseplates (P = .001; OR, 2.50) as significant risk factors. CONCLUSION: The incidence of aseptic glenoid baseplate loosening was 0.74% for the evaluated medialized glenoid-lateralized humerus rTSA system. Numerous risk factors for aseptic loosening were identified, including rheumatoid arthritis, diabetes, Walch type B2 and B3 glenoids, posteriorly-superiorly augmented baseplates, and expanded lateralized glenospheres. Finally, analysis of multiple combinations of risk factors identified patients and implant configurations with the greatest risk of aseptic glenoid loosening.

Does glenohumeral offset affect clinical outcomes in a lateralized reverse total shoulder arthroplasty?

BACKGROUND: Reverse total shoulder arthroplasty (rTSA) exhibits high rates of success and low complication rates. rTSA has undergone numerous design adaptations over recent years, and lateralization of implant components provides theoretical and biomechanical benefits in stability and range of motion (ROM) as well as decreased rates of notching. However, the magnitude of implant lateralization and its effect on these outcomes is less well understood. The purpose of this study was to evaluate how increasing glenohumeral offset affects outcomes after rTSA, specifically in a lateralized humerus + medialized glenoid implant model. METHODS: Primary rTSA using a lateralized humeral + medialized glenoid implant model performed at a single academic institution between 2012 and 2018 were retrospectively reviewed. Patient-reported outcome (PRO) parameters and clinical outcomes including ROM were evaluated both pre- and postoperatively. Pre- and postoperative radiographs were analyzed for measurement of glenohumeral offset, defined as the acromial-tuberosity offset (ATO) distance on the anteroposterior radiograph. RESULTS: A total of 130 rTSAs were included in the analysis, with a mean follow-up of 35 mo. The mean postoperative absolute ATO was 16 mm, and the mean delta ATO (difference from pre- to postoperatively) was 4.6 mm further lateralized. Among all study patients, improvements in all ROM parameters and all PROs were observed from pre- to postoperative assessments. When assessing for the effects of lateralization on these outcomes, multivariate analysis failed to reveal a significant effect from the absolute postoperative ATO or the delta ATO on any outcome parameter. CONCLUSIONS: rTSA using a lateralized humeral + medialized glenoid implant model exhibits excellent clinical outcomes in ROM and PROs. However, the magnitude of lateralization as measured radiographically by the ATO did not significantly affect these outcomes; patients exhibited universally good outcomes irrespective of the degree of offset restoration.

Impact of COVID-19 on clinical outcomes following total shoulder arthroplasty.

Background: The coronavirus (COVID-19) pandemic has introduced patient stressors and changes to perioperative protocols in total shoulder arthroplasty (TSA). The purpose of this study is to evaluate the short-term effects of the COVID-19 pandemic on various patient outcomes and satisfaction following elective TSA. Methods: A retrospective review was performed on 147 patients who underwent primary TSA at a single institution between June 2019 and December 2020. Patients were divided into 2 cohorts: pre-COVID (June 2019-March 2020; n = 74) and post-COVID (April 2020-December 2020; n = 73). No elective TSA were performed between 10 March 2020 and 23 April 2020 at our institution. Data were collected prospectively both pre- and postoperatively. Range of motion (ROM) testing included active abduction, internal rotation, and external rotation. Patient reported outcome measures (PROMs) included global shoulder function, Simple Shoulder Test, American Shoulder and Elbow Surgeons, Visual Analog Scale pain scoring systems, and patient satisfaction. ROM and PROMs were compared at preoperative, 3-month follow-up, and 12-month follow-up intervals. Operative time, length of stay (LOS), 90-day readmission, and 90-day reoperation were also compared. Results: There were no differences in baseline patient characteristics. The operative time, LOS, home discharge rate, readmission, and reoperation did not differ between groups. For both cohorts, the PROMs and ROM improved at each follow-up visit postoperatively. While preoperative abduction, internal rotation, and external rotation were significantly greater in the post-COVID group, all ROM measures were similar at 3-month and 12-month follow-up visits. There was no difference in pain, global function, Simple Shoulder Test, American Shoulder and Elbow Surgeons, or patient satisfaction between groups at all time intervals. Conclusions: Patients undergoing elective TSA amidst the COVID-19 pandemic demonstrate excellent PROMs, ROM, and high satisfaction up to 12-months postoperatively that are comparable to pre-pandemic standards. Operative time, LOS, discharge destination, as well as 90-day readmission and reoperation rates were not impacted by the pandemic. Patients can expect similar outcomes for TSA when comparing pre-COVID to post-COVID as the pandemic continues.

Three-dimensional finite element modeling of glenoid bone loss and baseplate fixation in reverse total shoulder arthroplasty.

Background: Posterior glenoid bone loss is frequently observed in patients with osteoarthritis undergoing reverse total shoulder arthroplasty. Glenoid bone loss can reduce the baseplate back support area and the number of screws for fixation. The purpose of this study is to determine how initial baseplate fixation is affected by biomechanical factors introduced by glenoid bone loss such as reduced baseplate back support area and reduced screw number using three-dimensional finite element analysis. Methods: Computerized tomography images of a healthy shoulder were selected and segmented to obtain the solid geometry. Solid models were generated with 100%, 75%, 67%, 50%, and 25% glenoid baseplate back support. With these geometries, two groups of finite element models were then built. In the bone loss areas, screws were maintained in one group of models but were removed in the other group of models. 750N compressive loading was applied along the direction parallel to the scapula axis. Maximum von Mises stress and maximum micromotion between the bone and implant were recorded and evaluated for each glenoid bone model. Results: In the group of models where all screws remained in place, the maximum stress and maximum micromotion between the bone and implant exhibited minimal variation. The maximum stresses were 21.10MPa and the maximum micromotions were between 2-3 µm. However, in the group of models removing screws in the bone loss areas, maximum stress increased from 20MPa to 45MPa and maximum micromotion increased from 2 µm to 85 µm as the backside support area decreased from 100% to 25%. Discussion: In conclusion, this three-dimensional finite element analysis study demonstrates that initial fixation can be achieved with approximately 1/3 posterior glenoid bone deficiency even without screw placement in the area of bone loss. Glenoid bone loss affects baseplate fixation mainly by reducing the screw numbers for fixation. If screws can be placed in the bone loss area, the decreased baseplate back support area will not result in increased stresses or micromotion leading to baseplate failure. This study suggests that surgeons should consider applying screws to the bone loss area if the remaining bone is able to hold the screw. Level of evidence: Computer Modeling Study.

Shoulder arthroplasty after prior anterior shoulder instability surgery: a matched cohort analysis.

PURPOSE: To evaluate the effect of prior anterior shoulder instability surgery (SIS) on the outcomes and complications of primary anatomic total shoulder arthroplasty (aTSA) and reverse total shoulder arthroplasty (rTSA). METHODS: Between 2007 and 2018, 38 primary total shoulder arthroplasties (TSA) (22 aTSA and 16 rTSA) with a prior SIS and a minimum of 2 years of follow-up were identified. This cohort was matched 1:3 based on age, sex, body mass index, year of surgery, and dominant shoulder. aTSA and rTSA were matched to patients with primary osteoarthritis (OA) and rotator cuff tear arthropathy (CTA), respectively. RESULTS: TSA produced similar postoperative pain, ROM, patient-reported outcome measures, complications, and revisions in those with prior SIS vs. controls. aTSA with prior SIS demonstrated worse final postoperative abduction (116° vs. 133°; P = 0.046) and abduction improvement (24° vs. 47°; P = 0.034) compared to OA controls. Both aTSA and rTSA with prior SIS demonstrated significant improvements from baseline across all metrics, with no significant differences between the groups. aTSA and rTSA with prior SIS demonstrated no differences to controls in complications (4.6% vs. 6.1%; P = .786 and 0% vs. 6.3%. P = .183) or revisions (4.6% vs. 4.6%; P = .999 and 0% vs. 4.2%; P = .279). CONCLUSIONS: TSA after prior SIS surgery can improve both pain and function without adversely increasing the rates of complications or revision surgery. When compared to patients without prior SIS, aTSA demonstrated worse abduction; however, all other functional differences remained statistically similar. LEVEL OF EVIDENCE: III; Retrospective Cohort Comparison; Treatment Study.

Clinical and radiographic outcomes following reverse total shoulder arthroplasty in patients 60 years of age and younger.

BACKGROUND: Although initially indicated for use in older patients, reverse total shoulder arthroplasty (rTSA) is being increasingly used in younger patients. The purpose of this study is to compare the clinical and radiographic outcomes of patients aged <60 years to those aged 60-79 years following primary rTSA. METHODS: 154 patients aged <60 years and 1763 patients aged 60-79 years were identified from an international multi-institutional Western Institutional Review Board-approved registry with a minimum 2 years' follow-up. All patients were evaluated and scored preoperatively and at latest follow-up using 5 outcome scoring metrics and 4 active range of motion (ROM) measurements. RESULTS: Patients aged <60 years were more often male (P = .023), had a higher body mass index (P = .001), higher rates of previous surgery (57% vs. 27%, P < .001), higher rates of post-traumatic arthritis (11% vs. 5%, P < .001) and inflammatory arthropathy (13% vs. 4%, P < .001), and lower rates of rotator cuff tear arthropathy (25% vs. 38%, P = .006). There were no differences in ROM between the groups but patients aged <60 years had significantly lower function and outcome metric scores and higher pain scores at latest follow-up. Adverse event rates were similar between the 2 groups, but patients aged <60 years were more likely to require revision (5.2% vs. 1.8%, P = .004). Patients aged <60 years also had lower satisfaction scores (much better/better 86% vs. 92%, P = .006). CONCLUSION: At a mean follow-up of 47 months, primary rTSA patients aged <60 years had worse clinical outcomes compared with those aged 60-79 years, with lower outcome scores, increased pain, lower function scores, and less patient satisfaction. Patients aged <60 years had higher rates of previous surgery, inflammatory arthropathy, and post-traumatic arthritis, whereas those aged 60-79 years had higher rates of rotator cuff tear arthropathy. Although complications were similar, younger patients had 3 times the risk of revision rTSA.

Assessing the hospital volume-outcome relationship in total elbow arthroplasty.

BACKGROUND: Total elbow arthroplasty (TEA) is an effective intervention for multiple elbow disorders including complex fracture in elderly patients, post-traumatic arthropathy, inflammatory arthropathy, and distal humeral nonunion. Given its known therapeutic value and low utilization rate, an investigation into the thresholds for TEA institutional volume-outcome relationships is warranted. The purpose of this study was to identify TEA volume thresholds that serve as predictors of institutional outcomes including complications, readmissions, revisions, cost of care, length of stay (LOS), and non-home discharge. We hypothesized that increased institutional volume would be associated with decreased 90-day adverse outcomes and resource utilization. METHODS: The Nationwide Readmission Database was queried from 2010 to 2017 to identify all cases of TEA. Hospital volume was calculated using a unique hospital identifier and divided into quartiles. Outcomes such as complications, readmissions, revisions, cost of care, LOS, and non-home discharge were then analyzed by quartile. The same outcomes were assessed via stratum-specific likelihood ratio (SSLR) analysis to define volume strata among institutions. RESULTS: SSLR analysis defined statistically significant hospital volume categories for each 90-day outcome. The volume category with the lowest complication rate was ≥21 TEAs per year (5.6%). The volume categories with the lowest readmission rates were 1-3 TEAs per year (4.7%) and ≥18 TEAs per year (9.2%). Revision rates were lowest in the volume categories of 1-5 TEAs per year (0.1%) and ≥18 TEAs per year (0.1%). Hospitals with ≥21 TEAs per year had the lowest cost of care and the highest rate of extended LOS (>2 days). SSLR analysis showed that non-home discharges decreased in a stepwise manner as volume increased. The lowest non-home discharge rate was associated with the volume category of ≥22 TEAs per year (20.3%). CONCLUSION: This study defines TEA volume strata for institutional outcomes. The highest TEA volume strata were associated with the lowest rates of 90-day complications, revisions, and non-home discharges and the lowest cost of care. This trend is likely attributable to the benefits of high-volume institutional experience and standardized patient-care processes.

Variability and reliability of 2-dimensional vs. 3-dimensional glenoid version measurements with 3-dimensional preoperative planning software.

BACKGROUND: Preoperative planning for total shoulder arthroplasty (TSA) may change according to the measured degree of glenoid version. Both 2-dimensional (2D) and 3-dimensional (3D) computed tomographic (CT) scans are used to measure glenoid version, with no consensus on which method is more accurate. However, it is generally accepted that 3D measurements are more reliable, yet most 3D reconstruction software currently in clinical use have never been directly compared to 2D. The purpose of this study is to directly compare 2D and 3D glenoid version measurements and determine the differences between the two. METHODS: CT scans were performed preoperatively on 315 shoulders undergoing either anatomic or reverse TSA. 2D measurements of glenoid version were obtained manually using the Friedman method, whereas 3D measurements were obtained using the Equinoxe Planning Application (Exactech Inc.) 3D-reconstruction software. Negative version values indicate retroversion, whereas positive values indicate anteversion. Two observers collected the 2D measurements 2 separate times, and intra- and interobserver measurements were calculated. Groups were compared for variability using intraclass correlation coefficients (ICCs), and for differences in sample means using Student t tests. Additionally, samples were stratified by version value in order to better understand the potential sources of error between measurement techniques. RESULTS: For the 2D measurements, intraobserver variability indicated excellent reproducibility for both observer 1 (ICC = 0.928, 95% confidence interval [CI] 0.911-0.942) and observer 2 (ICC = 0.964, 95% CI 0.955-0.971). Interobserver variability measurements also indicated excellent reproducibility (ICC = 0.915, 95% CI 0.778-0.956). The overall 2D version measurement average (-4.9° ± 10.3°) was significantly less retroverted than the 3D measurement average (-8.4° ± 9.1°) (P < .001), with 3D measurements yielding a more retroverted value 73% of the time. When stratified on the basis of version value with outliers excluded, there was no significant difference in the distribution of high-error samples within the data. DISCUSSION: There was excellent reproducibility between the 2 observers in terms of both intra- and interobserver variability. The 3D measurement techniques were significantly more likely to return a more retroverted measurement, and high-error samples were evenly distributed throughout the data, indicating that there were no discernable trends in the degree of error observed. Shoulder surgeons should be aware that different glenoid version measurement strategies can yield different version measurements, as these can affect preoperative planning and surgeon decision making.

Effects of obesity on clinical and functional outcomes following anatomic and reverse total shoulder arthroplasty.

BACKGROUND: Limited data exist regarding the clinical and functional outcomes following primary total shoulder arthroplasty in obese patients. The purpose of this study is to determine the effects of obesity on the clinical and functional outcomes following primary anatomic total shoulder arthroplasty (aTSA) and reverse total shoulder arthroplasty (rTSA) in a large patient population with mid-term follow-up. METHODS: Patients in a multi-institutional shoulder registry receiving either primary aTSA (n = 1520) or rTSA (n = 2054) from 2004 to 2018 with a minimum follow-up period of 2 years were studied. All patients received the same single-platform shoulder prosthesis. Study groups were assigned based on implant type (anatomic or reverse), and further stratification was based on patient body mass index (BMI), with obese patients having a BMI ≥ 30 and non-obese patients having a BMI < 30. Patients were evaluated and scored preoperatively and at latest follow-up by use of 5 scoring metrics and range of motion (ROM). RESULTS: The mean follow-up period was 5 years (range, 2-14 years). Obese patients comprised 41% of the aTSA group and 35% of the rTSA group. Significant postoperative improvements in visual analog scale pain scores, ROM, and all 5 scoring metrics occurred in both obese and non-obese patients (P < .05). Obese patients in both groups reported higher preoperative and postoperative visual analog scale pain scores and less preoperative and postoperative ROM compared with non-obese patients. Compared with non-obese patients, obese patients receiving aTSA reported significantly worse postoperative Simple Shoulder Test, Constant-Murley, American Shoulder and Elbow Surgeons, University of California, Los Angeles, and Shoulder Pain and Disability Index scores compared with non-obese patients, and those receiving rTSA reported significantly worse American Shoulder and Elbow Surgeons and Shoulder Pain and Disability Index scores (all P < .05). However, these differences did not exceed the minimal clinically important difference or substantial clinical benefit criteria. Radiographic analysis showed that in the rTSA group, obese patients had significantly less postoperative scapular notching and a lower scapular notching grade compared with non-obese patients (P < .05). DISCUSSION: Both non-obese and obese patients can expect clinically significant improvements in pain, motion, and functional outcome scores following both aTSA and rTSA. Obese patients reported significantly more postoperative pain, lower outcome scores, and less ROM compared with non-obese patients after both aTSA and rTSA at a mean follow-up of 5 years. However, statistically significant differences were not found to be clinically significant with respect to established minimal clinically important difference and substantial clinical benefit criteria. Therefore, obese and non-obese patients experience similar clinical outcomes following total shoulder arthroplasty, regardless of BMI. However, obese patients have more comorbidities, greater intraoperative blood loss, and less scapular notching compared with non-obese patients.