Aims. Vascular compromise due to arterial injury is a rare but serious complication of a proximal humeral fracture. The aims of this study were to report its incidence in a large urban population, and to identify clinical and radiological factors which are associated with this complication. We also evaluated the results of the use of our protocol for the management of these injuries. Methods. A total of 3,497 adult patients with a proximal humeral fracture were managed between January 2015 and December 2022 in a single tertiary trauma centre. Their mean age was 66.7 years (18 to 103) and 2,510 (72%) were female. We compared the demographic data, clinical features, and configuration of those whose fracture was complicated by vascular compromise with those of the remaining patients. The incidence of vascular compromise was calculated from national population data, and predictive factors for its occurrence were investigated using univariate analysis. Results. A total of 18 patients (0.5%) had a proximal humeral fracture and clinical evidence of vascular compromise, giving an annual incidence of 0.29 per 100,000 of the population. Their mean age was 68.7 years (45 to 92) and ten (56%) were female. Evidence of a mixed pattern neurological deficit (brachial plexus palsy) (odds ratio (OR) 380.6 (95% CI 85.9 to 1,685.8); p < 0.001), complete separation of the proximal shaft from the humeral head with medial displacement (OR 39.5 (95% CI 14.0 to 111.8); p < 0.001), and a fracture-dislocation (OR 5.0 (95% CI 1.6 to 15.3); p = 0.015) were all associated with an increased risk of associated vascular compromise. A policy of reduction and fixation of the fracture prior to vascular surgical intervention had favourable outcomes without vascular sequelae. Conclusion. The classic signs of distal ischaemia are often absent in patients with proximal injuries to major vessels. We were able to identify specific clinical and radiological ‘red flags’ which, particularly when present in combination, should increase the suspicion of a fracture with an associated vascular injury, and facilitate early diagnosis and appropriate combined orthopaedic and vascular intervention. Cite this article: Bone Joint J 2024;106-B(8):842–848

Aims. The aim of this study was to review the provision of total elbow arthroplasties (TEAs) in England, including the incidence, the characteristics of the patients and the service providers, the types of implant, and the outcomes. Methods. We analyzed the primary TEAs recorded in the National Joint Registry (NJR) between April 2012 and December 2022, with mortality data from the Civil Registration of Deaths dataset. Linkage with Hospital Episode Statistics-Admitted Patient Care (HES-APC) data provided further information not collected by the NJR. The incidences were calculated using estimations of the populations from the Office for National Statistics. The annual number of TEAs performed by surgeons and hospitals was analyzed on a national and regional basis. Results. A total of 3,891 primary TEAs were included. The annual incidence of TEA was between 0.72 and 0.82 per 100,000 persons before 2020 and declined to 0.4 due to a decrease in elective TEAs during the COVID-19 pandemic, with a slight recovery in 2022. Older patients, those of white ethnicity and females, were more likely to undergo TEA. Those who underwent elective TEA had a median wait of between 89 (IQR 41 to 221) and 122 days (IQR 74 to 189) in the years before 2021, and this increased to 183 days (IQR 66 to 350) in 2021. The number of TEAs performed by surgeons per annum remained unchanged, with a median of two (IQR 1 to 3). The median annual number of TEAs per region was three to six times higher than the median annual case load of the highest volume hospital in a region. Patients in the lowest socioeconomic group had a higher rate of serious adverse events and mortality (11%) when undergoing TEA for acute trauma. Conclusion. In England, TEA is more common in older age groups, those of white ethnicity, and females. The COVID-19 pandemic affected the incidence of elective TEA and waiting times, and the provision of TEA has not yet recovered. The Getting it Right First Time recommendation of centralizing services to one centre per region could result in up to a six-fold increase in the number of TEAs being performed in some centres. Cite this article: Bone Joint J 2024;106-B(11):1312–1320

Aims. The aim of this study was to compare the characteristics and outcomes of L-shaped and reverse L-shaped rotator cuff tears. Methods. A total of 82 shoulders (81 patients) after arthroscopic rotator cuff repair were retrospectively enrolled. The mean age of the patients was 62 years (SD 6), 33 shoulders (40.2%) were in male patients, and 57 shoulders (69.5%) were the right shoulder. Of these, 36 shoulders had an L-shaped tear (group L) and 46 had a reverse L-shaped tear (group RL). Both groups were compared regarding characteristics, pre- and postoperative pain, and functional outcomes. Muscle status was assessed by preoperative MRI, and re-tear rates by postoperative ultrasonography or MRI. Results. Patients in group RL were significantly older than in group L (p = 0.008), and group RL was significantly associated with female sex (odds ratio 2.5 (95% confidence interval 1.03 to 6.32); p = 0.041). Mean postoperative pain visual analogue scale (VAS) score was significantly greater (group L = 0.8 (SD 1.5), group RL = 1.7 (SD 2.2); p = 0.033) and mean postoperative American Shoulder and Elbow Surgeons (ASES) score was significantly lower in group RL than group L (group L = 91.4 (SD 13.1), group RL = 83.8 (SD 17.9); p = 0.028). However, postoperative mean VAS for pain and ASES score were not lower than the patient-acceptable symptom state scores. Mean retracted tear length was significantly larger in group L (group L = 24.6 mm (SD 6.5), group RL = 20.0 mm (SD 6.8); p = 0.003). Overall re-tear rate for 82 tears was 11.0% (nine shoulders), and re-tear rates in group L and RL were similar at 11.1% (four shoulders) and 10.9% (five shoulders), respectively (p = 1.000). No significant intergroup difference was found for fatty degeneration (FD) or muscle atrophy. Within group L, postoperative FD grades of supraspinatus and subscapularis worsened significantly (p = 0.034 and p = 0.008, respectively). Mean postoperative pain VAS (male = 1.2 (SD 1.8), female = 1.3 (SD 2.0)) and ASES scores (male = 88.7 (SD 15.5), female = 86.0 (SD 16.8)) were similar in male and female patients (p = 0.700 and p = 0.475, respectively). Regression analysis showed age was not a prognostic factor of postoperative pain VAS or ASES scores (p = 0.188 and p = 0.150, respectively). Conclusion. Older age and female sex were associated with reverse L-shaped tears. Although the postoperative functional outcomes of patients with reverse L-shaped tears were satisfactory, the clinical scores were poorer than those of patients with L-shaped tears. Surgeons should be aware of the differences in clinical outcome between L-shaped and reverse L-shaped rotator cuff tears. Cite this article: Bone Joint J 2022;104-B(3):394–400

Aims. This study aims to describe a new method that may be used as a supplement to evaluate humeral rotational alignment during intramedullary nail (IMN) insertion using the profile of the perpendicular peak of the greater tuberosity and its relation to the transepicondylar axis. We called this angle the greater tuberosity version angle (GTVA). Methods. This study analyzed 506 cadaveric humeri of adult patients. All humeri were CT scanned using 0.625 × 0.625 × 0.625 mm cubic voxels. The images acquired were used to generate 3D surface models of the humerus. Next, 3D landmarks were automatically calculated on each 3D bone using custom-written C++ software. The anatomical landmarks analyzed were the transepicondylar axis, the humerus anatomical axis, and the peak of the perpendicular axis of the greater tuberosity. Lastly, the angle between the transepicondylar axis and the greater tuberosity axis was calculated and defined as the GTVA. Results. The value of GTVA was 20.9° (SD 4.7°) (95% CI 20.47° to 21.3°). Results of analysis of variance revealed that females had a statistically significant larger angle of 21.95° (SD 4.49°) compared to males, which were found to be 20.49° (SD 4.8°) (p = 0.001). Conclusion. This study identified a consistent relationship between palpable anatomical landmarks, enhancing IMN accuracy by utilizing 3D CT scans and replicating a 20.9° angle from the greater tuberosity to the transepicondylar axis. Using this angle as a secondary reference may help mitigate the complications associated with malrotation of the humerus following IMN. However, future trials are needed for clinical validation. Cite this article: Bone Jt Open 2024;5(10):929–936

Aims. The aim of this study was to characterize the influence of social deprivation on the rate of complications, readmissions, and revisions following primary total shoulder arthroplasty (TSA), using the Social Deprivation Index (SDI). The SDI is a composite measurement, in percentages, of seven demographic characteristics: living in poverty, with < 12 years of education, single-parent households, living in rented or overcrowded housing, households without a car, and unemployed adults aged < 65 years. Methods. Patients aged ≥ 40 years, who underwent primary TSA between 2011 and 2017, were identified using International Classification of Diseases (ICD)-9 Clinical Modification and ICD-10 procedure codes for TSA in the New York Statewide Planning and Research Cooperative System database. Readmission, reoperation, and other complications were analyzed using multivariable Cox proportional hazards regression controlling for SDI, age, ethnicity, insurance status, and Charlson Comorbidity Index. Results. A total of 17,698 patients with a mean age of 69 years (SD 9.6), of whom 57.7% were female, underwent TSA during this time and 4,020 (22.7%) had at least one complication. A total of 8,113 patients (45.8%) had at least one comorbidity, and the median SDI in those who developed complications 12 months postoperatively was significantly greater than in those without a complication (33 vs 38; p < 0.001). Patients from areas with higher deprivation had increased one-, three-, and 12-month rates of readmission, dislocation, humeral fracture, urinary tract infection, deep vein thrombosis, and wound complications, as well as a higher three-month rate of pulmonary embolism (all p < 0.05). Conclusion. Beyond medical complications, we found that patients with increased social deprivation had higher rates of humeral fracture and dislocation following primary TSA. The large sample size of this study, and the outcomes that were measured, add to the literature greatly in comparison with other large database studies involving TSA. These findings allow orthopaedic surgeons practising in under-served or low-volume areas to identify patients who may be at greater risk of developing complications. Cite this article: Bone Joint J 2024;106-B(2):174–181

Aims. The outcomes following nonoperative management of minimally displaced greater tuberosity (GT) fractures, and the factors which influence patient experience, remain poorly defined. We assessed the early patient-derived outcomes following these injuries and examined the effect of a range of demographic- and injury-related variables on these outcomes. Methods. In total, 101 patients (53 female, 48 male) with a mean age of 50.9 years (19 to 76) with minimally displaced GT fractures were recruited to a prospective observational cohort study. During the first year after injury, patients underwent experiential assessment using the Disabilities of the Arm, Shoulder and Hand (DASH) score and assessment of associated injuries using MRI performed within two weeks of injury. The primary outcome was the one-year DASH score. Multivariate analysis was used to assess the effect of patient demographic factors, complications, and associated injuries, on outcome. Results. The mean DASH score improved from 42.3 (SD 9.6) at six weeks post-injury, to 19.5 (SD 14.3) at one-year follow-up (p < 0.001), but outcomes were mixed, with 30 patients having a DASH score > 30 at one year. MRI revealed a range of associated injuries, with a full-thickness rotator cuff tear present in 19 patients (19%). Overall, 11 patients (11%) developed complications requiring further operative intervention; 20 patients (21%) developed post-traumatic secondary shoulder stiffness. Multivariate analysis revealed a high-energy mechanism (p = 0.009), tobacco consumption (p = 0.033), use of mobility aids (p = 0.047), a full-thickness rotator cuff tear (p = 0.002), and the development of post-traumatic secondary shoulder stiffness (p = 0.035) were independent predictors of poorer outcome. Conclusion. The results of nonoperative management of minimally displaced GT fractures are heterogeneous. While many patients have satisfactory early outcomes, a substantial subgroup fare much worse. There is a high prevalence of rotator cuff injuries and post-traumatic shoulder stiffness, and their presence is associated with poorer patient experience. Furthermore, patients who have a high-energy injury, smoke, or use walking aids, have worse outcomes. Cite this article: Bone Joint J 2023;105-B(5):534–542

Aims. The open Latarjet procedure is a widely used treatment for recurrent anterior instability of the shoulder. Although satisfactory outcomes are reported, factors which influence a patient’s experience are poorly quantified. The aim of this study was to evaluate the effect of a range of demographic factors and measures of the severity of instability on patient-reported outcome measures in patients who underwent an open Latarjet procedure at a minimum follow-up of two years. Methods. A total of 350 patients with anterior instability of the shoulder who underwent an open Latarjet procedure between 2005 and 2018 were reviewed prospectively, with the collection of demographic and psychosocial data, preoperative CT, and complications during follow-up of two years. The primary outcome measure was the Western Ontario Shoulder Instability Index (WOSI), assessed preoperatively, at two years postoperatively, and at mid-term follow-up at a mean of 50.6 months (SD 24.8) postoperatively. The secondary outcome measure was the abbreviated version of the Disabilities of the Arm, Shoulder and Hand (QuickDASH) score. The influence of the demographic details of the patients, measurements of the severity of instability, and the complications of surgery were assessed in a multivariate analysis. Results. The mean age of the patients was 25.5 years (22 to 32) and 27 (7.7%) were female. The median time to surgery after injury was 19 months (interquartile range (IQR) 13 to 39). Seven patients developed clinically significant complications requiring further intervention within two years of surgery. The median percentage WOSI deficiency was 8.0% (IQR 4 to 20) and median QuickDASH was 3.0 (IQR 0 to 9) at mid-term assessment. A minority of patients reported a poorer experience, and 22 (6.3%) had a > 50% deficiency in WOSI score. Multivariate analysis revealed that consumption of ≥ 20 units of alcohol/week, a pre-existing affective disorder or epilepsy, medicolegal litigation, increasing time to surgery, and residing in a more socioeconomically deprived area were independently predictive of a poorer WOSI score. Conclusion. Although most patients treated by an open Latarjet procedure have excellent outcomes at mid-term follow-up, a minority have poorer outcomes, which are mainly predictable from pre-existing demographic factors, rather than measures of the severity of instability. Cite this article: Bone Joint J 2023;105-B(4):389–399

Aims. Optimal glenoid positioning in reverse shoulder arthroplasty (RSA) is crucial to provide impingement-free range of motion (ROM). Lateralization and inclination correction are not yet systematically used. Using planning software, we simulated the most used glenoid implant positions. The primary goal was to determine the configuration that delivers the best theoretical impingement-free ROM. Methods. With the use of a 3D planning software (Blueprint) for RSA, 41 shoulders in 41 consecutive patients (17 males and 24 females; means age 73 years (SD 7)) undergoing RSA were planned. For the same anteroposterior positioning and retroversion of the glenoid implant, four different glenoid baseplate configurations were used on each shoulder to compare ROM: 1) no correction of the RSA angle and no lateralization (C-L-); 2) correction of the RSA angle with medialization by inferior reaming (C+M+); 3) correction of the RSA angle without lateralization by superior compensation (C+L-); and 4) correction of the RSA angle and additional lateralization (C+L+). The same humeral inlay implant and positioning were used on the humeral side for the four different glenoid configurations with a 3 mm symmetric 135° inclined polyethylene liner. Results. The configuration with lateralization and correction of the RSA angle (C+L+) led to better ROM in flexion, extension, adduction, and external rotation (p ≤ 0.001). Only internal rotation was not significantly different between groups (p = 0.388). The configuration where correction of the inclination was done by medialization (C+M+) led to the worst ROM in adduction, extension, abduction, flexion, and external rotation of the shoulder. Conclusion. Our software study shows that, when using a 135° inlay reversed humeral implant, correcting glenoid inclination (RSA angle 0°) and lateralizing the glenoid component by using an angled bony or metallic augment of 8 to 10 mm provides optimal impingement-free ROM. Cite this article: Bone Jt Open 2024;5(10):851–857

Aims. To propose a new method for evaluating paediatric radial neck fractures and improve the accuracy of fracture angulation measurement, particularly in younger children, and thereby facilitate planning treatment in this population. Methods. Clinical data of 117 children with radial neck fractures in our hospital from August 2014 to March 2023 were collected. A total of 50 children (26 males, 24 females, mean age 7.6 years (2 to 13)) met the inclusion criteria and were analyzed. Cases were excluded for the following reasons: Judet grade I and Judet grade IVb (> 85° angulation) classification; poor radiograph image quality; incomplete clinical information; sagittal plane angulation; severe displacement of the ulna fracture; and Monteggia fractures. For each patient, standard elbow anteroposterior (AP) view radiographs and corresponding CT images were acquired. On radiographs, Angle P (complementary to the angle between the long axis of the radial head and the line perpendicular to the physis), Angle S (complementary to the angle between the long axis of the radial head and the midline through the proximal radial shaft), and Angle U (between the long axis of the radial head and the straight line from the distal tip of the capitellum to the coronoid process) were identified as candidates approximating the true coronal plane angulation of radial neck fractures. On the coronal plane of the CT scan, the angulation of radial neck fractures (CTa) was measured and served as the reference standard for measurement. Inter- and intraobserver reliabilities were assessed by Kappa statistics and intraclass correlation coefficient (ICC). Results. Angle U showed the strongest correlation with CTa (p < 0.001). In the analysis of inter- and intraobserver reliability, Kappa values were significantly higher for Angles S and U compared with Angle P. ICC values were excellent among the three groups. Conclusion. Angle U on AP view was the best substitute for CTa when evaluating radial neck fractures in children. Further studies are required to validate this method. Cite this article: Bone Joint J 2024;106-B(9):964–969

Aims. The aim of this study was to determine whether there is a correlation between the grade of humeral osteoarthritis (OA) and the severity of glenoid morphology according to Walch. We hypothesized that there would be a correlation. Methods. Overal, 143 shoulders in 135 patients (73 females, 62 males) undergoing shoulder arthroplasty surgery for primary glenohumeral OA were included consecutively. Mean age was 69.3 years (47 to 85). Humeral head (HH), osteophyte length (OL), and morphology (transverse decentering of the apex, transverse, or coronal asphericity) on radiographs were correlated to the glenoid morphology according to Walch (A1, A2, B1, B2, B3), glenoid retroversion, and humeral subluxation on CT images. Results. Increased humeral OL correlated with a higher grade of glenoid morphology (A1-A2-B1-B2-B3) according to Walch (r = 0.672; p < 0.0001). It also correlated with glenoid retroversion (r = 0.707; p < 0.0001), and posterior humeral subluxation (r = 0.452; p < 0.0001). A higher humeral OL (odds ratio (OR) 1.17; 95% confidence interval (CI) 1.03 to 1.32; p = 0.013), posterior humeral subluxation (OR 1.11; 95% CI 1.01 to 1.22; p = 0.031), and glenoid retroversion (OR 1.48; 95% CI 1.30 to 1.68; p < 0.001) were independent factors for a higher glenoid morphology. More specifically, a humeral OL of ≥ 13 mm was indicative of eccentric glenoid types B2 and B3 (OR 14.20; 95% CI 5.96 to 33.85). Presence of an aspherical HH in the coronal plane was suggestive of glenoid types B2 and B3 (OR 3.34; 95% CI 1.67 to 6.68). Conclusion. The criteria of humeral OL and HH morphology are associated with increasing glenoid retroversion, posterior humeral subluxation, and eccentric glenoid wear. Therefore, humeral radiological parameters might hint at the morphology on the glenoid side. Cite this article: Bone Jt Open 2022;3(6):463–469

Aims. The purpose of this study was to determine whether there were long-term differences in outcomes of reverse shoulder arthroplasty (RSA) undertaken for acute proximal humeral fracture versus rotator cuff deficiency with a minimum follow-up of five years. Methods. This was a prospective cohort study comparing 67 patients with acute complex proximal humeral fracture and 64 patients with irreparable rotator cuff deficiency who underwent primary RSA. In the fracture group, there were 52 (77.6%) females and 15 (22.4%) males, with a mean age of 73.5 years (51 to 85), while in the arthropathy group, there were 43 (67.1%) females and 21 (32.9%) males, with a mean age of 70.6 years (50 to 84). Patients were assessed by the Constant score, University of California Los Angeles shoulder score (UCLA), short version of the Disability of the Arm Shoulder and Hand score (QuickDASH), and visual analogue scales (VAS) for pain and satisfaction. Radiological evaluation was also performed. Results. Mean follow-up was 8.4 years (5 to 11). There were no significant differences in mean absolute (p = 0.125) or adjusted (p = 0.569) Constant, UCLA (p = 0.088), QuickDASH (p = 0.135), VAS-pain (p = 0.062), or range of movement at the final follow-up. However, patient satisfaction was significantly lower in the fracture group (p = 0.002). The complication rate was 1.5% (one patient) versus 9.3% (six patients), and the revision rate was 1.5% (one patient) versus 7.8% (five patients) in the fracture and arthropathy groups, respectively. The ten-year arthroplasty survival was not significantly different (p = 0.221). Conclusion. RSA may be used not only for patients with irreparable rotator cuff deficiencies, but also for those with acute complex proximal humeral fractures. We found that RSA provided similar functional outcomes and a low revision rate for both indications at long-term. However, satisfaction is lower in patients with an acute fracture. Cite this article: Bone Joint J 2020;102-B(11):1555–1559

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Shoulder arthroplasty is effective in the management of end-stage glenohumeral joint arthritis. However, it is major surgery and patients must balance multiple factors when considering the procedure. An understanding of patients’ decision-making processes may facilitate greater support of those considering shoulder arthroplasty and inform the outcomes of future research.

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The aim of this study is to report the implant survival and factors associated with revision of total elbow arthroplasty (TEA) using data from the Dutch national registry.

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The risk factors for recurrent instability (RI) following a primary traumatic anterior shoulder dislocation (PTASD) remain unclear. In this study, we aimed to determine the rate of RI in a large cohort of patients managed nonoperatively after PTASD and to develop a clinical prediction model.

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The aim of this study was to longitudinally compare the clinical and radiological outcomes of anatomical total shoulder arthroplasty (aTSA) up to long-term follow-up, when using cemented keel, cemented peg, and hybrid cage peg glenoid components and the same humeral system.

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The survival of humeral hemiarthroplasties in patients with relatively intact glenoid cartilage could theoretically be extended by minimizing the associated postoperative glenoid erosion. Ceramic has gained attention as an alternative to metal as a material for hemiarthroplasties because of its superior tribological properties. The aim of this study was to assess the in vitro wear performance of ceramic and metal humeral hemiarthroplasties on natural glenoids.

Aims. The purpose of this study was to report bone adaptive changes after anatomical total shoulder arthroplasty (TSA) using a standard-length hydroxyapatite (HA)-coated humeral component, and to report on a computer-based analysis of radiographs to determine changes in peri-implant bone density objectively. Methods. A total of 44 TSAs, performed between 2011 and 2014 using a cementless standard-length humeral component proximally coated with HA, were included. There were 23 males and 21 females with a mean age of 65 years (17 to 65). All shoulders had good quality radiographs at six weeks and five years postoperatively. Three observers graded bone adaptive changes. All radiographs were uploaded into a commercially available photographic software program. The grey value density of humeral radiological areas was corrected to the grey value density of the humeral component and compared over time. Results. Stress shielding was graded as mild in 14 shoulders and moderate in three; the greater tuberosity was the predominant site for stress shielding. The mean metaphyseal and diaphyseal fill-fit ratios were 0.56 (SD 0.1) and 0.5 (SD 0.07), respectively. For shoulders with no radiologically visible stress shielding, the mean decrease in grey value in zones 1 and 7 was 20%, compared with 38% in shoulders with radiologically visible stress shielding. Conclusion. The rate of moderate stress shielding was 7%, five years after implantation of a cementless standard-length HA-coated humeral component. Clinical observation of stress shielding identified on radiographs seems to represent a decrease in grey value of 25% or more. Cite this article: Bone Joint J 2021;103-B(5):958–963

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Rotator cuff disease (RCD) can considerably decrease quality of life. Here, we investigated whether health-related quality of life (HRQoL) influences the need for surgery in patients with RCD.

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Acute and chronic injuries of the interosseus membrane can result in longitudinal instability of the forearm. Reconstruction of the central band of the interosseus membrane can help to restore biomechanical stability. Different methods have been used to reconstruct the central band, including tendon grafts, bone-ligament-bone grafts, and synthetic grafts. This Idea, Development, Exploration, Assessment, and Long-term (IDEAL) phase 1 study aims to review the clinical results of reconstruction using a synthetic braided cross-linked graft secured at either end with an Endobutton to restore the force balance between the bones of the forearm.

Aims. To investigate the impact of the Charlson and Elixhauser comorbidity indices on patient-reported outcomes measures (PROMs) following shoulder arthroplasty. Methods. Patients undergoing total shoulder arthroplasty (TSA), reverse shoulder arthroplasty (RSA), or hemiarthroplasty (HA) from 2016 to 2018 were identified, along with the Charlson and Elixhauser comorbidities listed as their secondary diagnoses in the electronic medical records. Patients were matched to our institution’s registry to obtain their PROMs, including shoulder-specific (American Shoulder and Elbow Society (ASES) and Shoulder Activity Scale (SAS)) and general health scales (12-Item Short Form Survey (SF-12) and Patient-Reported Outcomes Measurement Information System-Pain Interference). Linear regression models adjusting for age and sex were used to evaluate the association between increasing number of comorbidities and PROM scores. A total of 1,817 shoulder arthroplasties were performed: 1,017 (56%) TSA, 726 (40%) RSA, and 74 (4%) HA. The mean age was 67 years (SD 10), and 936 (52%) of the patients were female. Results. The most common comorbidities were obesity (1,256, 69%) and hypertension (990, 55%). Patients with more comorbidities had lower ASES and SAS scores at baseline (p < 0.001). Elixhauser comorbidities continued to negatively impact ASES and SAS scores at one year (p = 0.002) and two-year follow-up (p = 0.002). Patients with more comorbidities reported greater pain interference on PROMIS at baseline (p = 0.007), but not at two years. Higher number of Charlson comorbidities were associated with lower scores on the SF-12 mental component at baseline (p < 0.001) and two years (p = 0.020). Higher number of Elixhauser comorbidities were associated with lower SF-12 physical component scores at baseline (p < 0.001) and two years (p = 0.004). Conclusion. Higher number of comorbidities was associated with lower baseline scores and worse outcomes on both shoulder-specific and general health PROMs. The presence of specific comorbidities may be used during shared decision-making to manage expectations for patients undergoing shoulder arthroplasty. Cite this article: Bone Joint J 2021;103-B(5):964–970