The influence of patient- and surgeon-specific factors on operative duration and early postoperative outcomes in shoulder arthroplasty

Do preoperative scapular fractures affect long-term outcomes after reverse shoulder arthroplasty?

BACKGROUND

Postoperative scapular stress fractures (SSFs) are a formidable problem after reverse shoulder arthroplasty (RSA). Less is known about patients who have these fractures preoperatively. The primary aim of this study was to examine postoperative satisfaction in patients undergoing primary RSA who have preoperative SSF and compared to a matched cohort without preoperative fracture. The secondary aim was to examine the differences in patient-reported outcomes between and within study cohorts.

METHODS

A retrospective chart review of primary RSAs performed by a single surgeon from 2000 to 2020 was conducted. Patients diagnosed with cuff tear arthropathy (CTA), massive cuff tear (MCT), or rheumatoid arthritis (RA) were included. Five hundred twenty-five shoulders met inclusion criteria. Fractures identified on preoperative computed tomography scans were divided into 3 groups: (1) os acromiale, (2) multifragments (MFs), and (3) Levy types. Seventy-two shoulders had an occurrence of SSF. The remaining 453 shoulders were separated into a nonfractured cohort. American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) and visual analog scale (VAS) scores were compared pre- and postoperatively in the total fracture group and the nonfractured group cohort. The multifragment subgroup was also compared to the pooled Os/Levy subgroup.

RESULTS

The total incidence of SSF in all shoulders was 13.7%. There was a difference in satisfaction scores at all time points between the nonfracture (7.9 ± 2.8) and total fracture group (5.4 ± 3.6, P < .001, at last visit). There was also a greater ASES total score in the nonfractured group vs the total fracture group at the final visit (69.4 ± 23.4 and 62.1 ± 24.2; P = .02). The MF group had worse ASES functional or VAS functional scores than the Os/Levy group at all time points: at 1 year, ASES function: MF 24.2 ± 14.5 and Os/Levy 30.7 ± 14.2 (P = .045); at 2 years, ASES function: MF 21.4 ± 14.4 and Os/Levy 35.5 ± 10.6 (P < .001); and at last follow-up, VAS function: MF 4.8 ± 2.8 and Os/Levy 6.4 ± 3.2 (P = .023).

DISCUSSION

Scapular fractures were proportionally most common in patients diagnosed with CTA (16.3%) compared with a 9.2% and 8.6% incidence in patients diagnosed with MCT and RA, respectively. Patients with preoperative SSF still see an improvement in ASES scores after RSA but do have lower satisfaction scores compared with the nonfractured cohort. The multifragment fracture group has lower functional and satisfaction scores at all postoperative time points compared with both the nonfracture and the Os/Levy fracture group.

Impact of Surgeon Case Volume on Outcomes After Reverse Total Shoulder Arthroplasty

INTRODUCTION

Despite a rapid increase in utilization of reverse total shoulder arthroplasty (rTSA), volume-outcome studies focusing on surgeon volume are lacking. Surgeon-specific volume-outcome studies may inform policymakers and provide insight into learning curves and measures of efficiency with greater case volume.

METHODS

This retrospective cohort study with longitudinal data included all rTSA cases as recorded in the Centers for Medicare & Medicaid Services Limited Data Set (2016 to 2018). The main effect was surgeon volume; this was categorized using two measures of surgeon volume: (1) rTSA case volume and (2) rTSA + TSA case volume. Volume cutoff values were calculated by applying a stratum-specific likelihood ratio analysis.

RESULTS

Among 90,318 rTSA cases performed by 7,097 surgeons, we found a mean annual rTSA surgeon volume of 6 ± 10 and a mean rTSA + TSA volume of 9 ± 14. Regression models using surgeon-specific rTSA volume revealed that surgery from low (<29 cases) compared with medium (29 to 96 cases) rTSA-volume surgeons was associated with a significantly higher 90-day all-cause readmission (odds ratio [OR], 1.17; confidence interval [CI], 1.10 to 1.25; P < 0.0001), higher 90-day readmission rates because of an infection (OR, 1.46; CI, 1.16 to 1.83; P = 0.0013) or dislocation (OR, 1.43; CI, 1.19 to 1.72; P = 0.0001), increased 90-day postoperative cost (+11.3% CI, 4.2% to 19.0%; P = 0.0016), and a higher transfusion rate (OR, 2.06; CI, 1.70 to 2.50; P < 0.0001). Similar patterns existed when using categorizations based on rTSA + TSA case volume.

CONCLUSION

Surgeon-specific volume-outcome relationships exist in this rTSA cohort, and we were able to identify thresholds that may identify low and medium/high volume surgeons. Observed volume-outcome relationships were independent of the definition of surgeon volume applied: either by focusing on the number of rTSAs performed per surgeon or anatomic TSAs performed.

LEVEL OF EVIDENCE

III.

Operative management of rotator cuff tears: identifying disparities in access on a national level

BACKGROUND

The purpose of this study was to identify nationwide disparities in the rates of operative management of rotator cuff tears based on race, ethnicity, insurance type, and socioeconomic status.

METHODS

Patients diagnosed with a full or partial rotator cuff tear from 2006 to 2014 were identified in the Healthcare Cost and Utilization Project's National Inpatient Sample database using International Classification of Diseases, Ninth Revision diagnosis codes. Bivariate analysis using chi-square tests and adjusted, multivariable logistic regression models were used to evaluate differences in the rates of operative vs. nonoperative management for rotator cuff tears.

RESULTS

This study included 46,167 patients. When compared with white patients, adjusted analysis showed that minority race and ethnicity were associated with lower rates of operative management for Black (adjusted odds ratio [AOR]: 0.31, 95% confidence interval [CI]: 0.29-0.33; P < .001), Hispanic (AOR: 0.49, 95% CI: 0.45-0.52; P < .001), Asian or Pacific Islander (AOR: 0.72, 95% CI: 0.61-0.84; P < .001), and Native American patients (AOR: 0.65, 95% CI: 0.50-0.86; P = .002). In comparison to privately insured patients, our analysis also found that self-payers (AOR: 0.08, 95% CI: 0.07-0.10; P < .001), Medicare beneficiaries (AOR: 0.76, 95% CI: 0.72-0.81; P < .001), and Medicaid beneficiaries (AOR: 0.33, 95% CI: 0.30-0.36; P < .001) had lower odds of receiving surgical intervention. Additionally, relative to those in the bottom income quartile, patients in all other quartiles experienced nominally higher rates of operative repair; these differences were statistically significant for the second quartile (AOR: 1.09, 95% CI: 1.03-1.16; P = .004).

CONCLUSION

There are significant nationwide disparities in the likelihood of receiving operative management for rotator cuff tear patients of differing race/ethnicity, payer status, and socioeconomic status. Further investigation is needed to fully understand and address causes of these discrepancies to optimize care pathways.

Increased operative time has a negative impact on clinical outcome in arthroscopic rotator cuff repair

BACKGROUND

Few data are available about the impact of operative time on outcome of rotator cuff repair.

AIM

The aim of this study was to evaluate the impact of operative time on clinical outcome and tendon healing after arthroscopic rotator cuff repair.

METHODS

Patients operated on for distal supraspinatus tear in our institution between 2012 and 2018 were included retrospectively. Operative time, from skin incision until skin closure, was extracted from medical files. For statistical analysis, operative time was treated as a quantitative variable. Endpoints were clinical outcome (Constant score, range of motion), tendon healing (on CT or MRI) and complications at 1 year. The significance threshold was set at p = 0.05.

RESULTS

A total of 219 Patients, with a mean age of 54.6 years (range 40-70 years), were included. Mean operative time 44.9 min (range 14-140 min). Significant correlations (p < 0.05) were found for Constant score and external rotation at 1 year: increasing operative time by 1 min led to a decrease in Constant score of 0.115 points, or 6.9 points for a 60-min increase (p = 0.0167) and a decrease in external rotation of 0.134°, or 8.04° for a 60-min increase (p = 0.0214). No significant correlations were found for anterior elevation at 1 year (p = 0.2577), tendon healing at 1 year (p = 0.295) or onset of complications during follow-up (p = 0.193).

DISCUSSION

The minimal clinically important difference in Constant score in patients undergoing rotator cuff surgery is between 6 and 10 points. An increase of more than 60 min in operative time significantly impacted clinical outcome of arthroscopic distal supraspinatus repair, but not tendon healing.

LEVEL OF EVIDENCE

Level III: Retrospective Cohort Design. Therapeutic Study.

An Analysis of Shoulder Surgeon Volume on Surgeon Competency, Hospital Costs, and Adverse Events: A Systematic Review

Purpose

The purpose of this systematic review is to assess the impact of shoulder surgeon volume of common shoulder procedures on hospital/surgeon efficiency, adverse events, and hospital costs.

Methods

Four online databases (PubMed, Embase, MEDLINE, and CENTRAL) were searched for literature on the influence of surgeon volume on outcomes for shoulder surgery, from data inception to October 1, 2020. The Methodological Index for Non-Randomized Studies tool was used to assess study quality. Data are presented descriptively.

Results

Twelve studies encompassing 150,898 patients were included in this review. The distribution of surgery type was rotator cuff repair (53.7%; n = 81,066), shoulder arthroplasty (35.7%; n = 53,833), and ORIF (10.6%; n = 15,999). Higher surgeon volume for rotator cuff repairs was associated with lower surgical time, length of stay, costs, and reoperation/readmission rates. For shoulder arthroplasty, higher surgeon volume was associated with lower length of stay, costs, surgical time, non-routine disposition, blood loss, reoperation/readmission, and complications. As for ORIF, higher surgeon volume was associated with lower length of stay, costs, and complications.

Conclusion

A high surgical volume leads to improved results for hospital/surgeon efficiency and reduces adverse events and hospital costs across various orthopaedic procedures. Hospitals and physicians can use this information to develop and adhere to policies and practices that contribute to more efficient and better-quality care for patients.

Level of Evidence

III.

Leveraging large, real-world data through machine-learning to increase efficiency in robotic-assisted total knee arthroplasty

PURPOSE

Increased operative time can be due to patient, surgeon and surgical factors, and may be predicted by machine learning (ML) modeling to potentially improve staff utilization and operating room efficiency. The purposes of our study were to: (1) determine how demographic, surgeon, and surgical factors affected operative times, and (2) train a ML model to estimate operative time for robotic-assisted primary total knee arthroplasty (TKA).

METHODS

A retrospective study from 2007 to 2020 was conducted including 300,000 unilateral primary TKA cases. Demographic and surgical variables were evaluated using Wilcoxon/Kruskal-Wallis tests to determine significant factors of operative time as predictors in the ML models. For the ML analysis of robotic-assisted TKAs (> 18,000), two algorithms were used to learn the relationship between selected predictors and operative time. Predictive model performance was subsequently assessed on a test data set comparing predicted and actual operative time. Root mean square error (RMSE), R² and percentage of predictions with an error < 5/10/15 min were computed.

RESULTS

Males, BMI > 40 kg/m² and cemented implants were associated with increased operative time, while age > 65yo, cementless, and high surgeon case volume had reduced operative time. Robotic-assisted TKA increased operative time for low-volume surgeons and decreased operative time for high-volume surgeons. Both ML models provided more accurate operative time predictions than standard time estimates based on surgeon historical averages.

CONCLUSIONS

This study demonstrated that greater surgeon case volume, cementless fixation, manual TKA, female, older and non-obese patients reduced operative time. ML prediction of operative time can be more accurate than historical averages, which may lead to optimized operating room utilization.

LEVEL OF EVIDENCE

III.

Increasing Patient Age, Ambulatory Surgery Center Setting, and Surgeon Experience Are Associated With Shorter Operative Duration for Anterior Cruciate Ligament Reconstruction

Purpose

To identify variables associated with operative duration and intraoperative or perioperative complications after primary anterior cruciate ligament reconstruction (ACLR).

Methods

Surgeons who performed a minimum of 20 arthroscopic cases per month were recruited for participation through the Arthroscopy Association of North America from 2011 through 2013. All participants agreed to voluntarily submit data for 6 months of consecutive knee and shoulder arthroscopy cases. Only subjects coded for ACLR were analyzed, whereas revision cases were excluded. ACLRs were subdivided into isolated ACLR, ACLR with minor concomitant procedures, and ACLR with major concomitant procedures. Patient, surgeon, and surgical variables were analyzed for their effect on operative duration and complications.

Results

One hundred thirty-five orthopaedic surgeons participated, providing 1,180 primary ACLRs (399 isolated ACLRs, 441 ACLRs plus minor procedures, and 340 ACLRs plus major procedures). Most surgeons were in private practice (72.8%). Most patients were male patients (58.8%), and the mean body mass index (BMI) was 26.2 ± 5.1. The overall mean operative duration was 95.9 ± 42.0 minutes (isolated ACLRs, 88.4 ± 36.8 minutes; ACLRs plus minor concomitant procedures, 90.1 ± 37.6 minutes; and ACLRs plus major concomitant procedures, 118.5 ± 112.4 minutes; P < .001). Patient age was inversely correlated with operative duration (ρ = –0.221, P < .001). Surgical procedures performed in an ambulatory surgery center had a shorter mean operative duration (91.5 ± 40.4 minutes) compared with those performed in a hospital setting (105.0 ± 43.8 minutes, P < .001). There were 22 intraoperative and 47 early postoperative complications, with the most common being deep vein thrombosis (n = 15). Surgical volume (knee arthroscopy cases per month) correlated inversely with operative time (ρ = –0.200, P = .001) and complication rate (ρ = –0.112, P < .001). Patient BMI was associated with increased odds of early postoperative complications on multivariate analysis (odds ratio, 1.060; P = .044; 95% confidence interval, 1.002-1.121).

Conclusions

Increasing patient age, private practice, ambulatory surgery center setting, and surgeon experience are associated with a shorter operative duration for ACLR. Although an increasing number of arthroscopic knee procedures performed by surgeons correlated with fewer complications, only increasing patient BMI significantly predicted odds of complications.

Level of Evidence

Level IV, prognostic case series.

Conversion of anatomic total shoulder arthroplasty to reverse shoulder arthroplasty using a unique hybrid glenoid component: technique and preliminary results

Background

Degenerative arthritis of the shoulder is a common condition that is successfully treated with anatomic total shoulder arthroplasty (TSA). Rotator cuff disease has evolved as a leading cause of failure of anatomic TSA, requiring revision to reverse shoulder arthroplasty (RSA). This revision procedure can be extremely complex, particularly if removal of a well-fixed glenoid component is necessary. This case series outlines the technique and preliminary clinical results of conversion of anatomic TSA to RSA utilizing both modular humeral and hybrid glenoid components.

Methods

From July 2017 to December 2019, the senior author (PMC) performed 84 consecutive anatomic TSA procedures utilizing a modular humeral arthroplasty system and a unique hybrid glenoid component. Three cases (3/84, or 3.6%) required conversion from anatomic TSA to RSA because of postoperative traumatic rotator cuff failure. All modular revision cases were performed without humeral stem removal and with utilization of the existing, well-fixed hybrid glenoid central titanium peg as the foundation for glenoid component revision. Preoperative and postoperative American Shoulder and Elbow Surgeons scores, visual analog scale pain scores, forward flexion, and patient satisfaction were analyzed in this modular revision group. In addition, several perioperative variables including operative time, blood loss, and length of stay were compared between this modular revision group and a nonmodular anatomic TSA to RSA revision comparative cohort.

Results

At an average follow-up of 24 months, average active forward flexion, postoperative American Shoulder and Elbow Surgeons scores, and visual analog scale pain scores improved significantly compared with preoperative scores in the modular revision group. All three patients were satisfied with their outcome. The average total operative time (109 minutes vs. 154 minutes, P = .02), blood loss (183 cc vs. 500 cc, P = .08), and length of hospital stay (26.3 hours vs. 36.6 hours P < .05) were lower in the modular revision group than those in a nonmodular revision cohort.

Conclusion

Revision of anatomic TSA to RSA utilizing a modular humeral system and a convertible hybrid glenoid component that does not require removal of a well-fixed central titanium peg which serves as the foundation for glenoid component revision was performed efficiently, safely, and successfully in three cases. This technique results in significantly improved clinical outcomes when revision to RSA is needed while potentially decreasing perioperative complications in the revision setting.

Development and validation of a predictive model for outcomes in shoulder arthroplasty: a multicenter analysis of nearly 2000 patients

BACKGROUND

Guiding expectations following shoulder arthroplasty is important in improving patient satisfaction. The purpose of this study was to develop a predictive model to calculate 2-year American Shoulder and Elbow Surgeons (ASES) scores in shoulder arthroplasty patients from a comprehensive set of preoperative patient factors and types of arthroplasty performed.

METHODS

This retrospective multicenter study included 1947 shoulder arthroplasties performed from 2010 to 2015 at 3 high-volume centers. Twenty-six variables were evaluated for an association with 2-year ASES scores, and variables with P < .20 in our pair-wise analysis were used to develop a predictive model. The prediction root-mean-square error was calculated. External validation was performed using data from 233 patients who underwent shoulder arthroplasty performed by a separate shoulder surgeon at a center not involved with creation of the predictive model.

RESULTS

A total of 1947 patients were analyzed, and their data were used to construct the predictive model. Variables most associated with 2-year ASES scores were patient age, preoperative ASES score, disability, chronic obstructive pulmonary disease, alcohol use, anatomic vs. reverse total shoulder arthroplasty, and primary vs. revision shoulder arthroplasty. By use of cross validation, the prediction error was 20.1, the proportion of variance explained was 25.3%, the mean absolute error was 15.9, and the C statistic for the linear regression model was 0.66. After external validation, the mean difference between predicted and actual 2-year ASES scores was 12.7 points, within the accepted minimal clinically important difference after shoulder arthroplasty.

DISCUSSION

Data from nearly 2000 shoulder arthroplasties allowed the development and validation of a model to predict 2-year ASES scores following shoulder arthroplasty. The model was accurate within the minimal clinically important difference in 85% of patients.

Trends in open shoulder surgery among early career orthopedic surgeons: who is doing what?

BACKGROUND

The incidence of various open shoulder procedures has changed over time. In addition, various fellowships provide overlapping training in open shoulder surgery. There is a lack of information regarding the relationship between surgeon training and open shoulder procedure type and incidence in early career orthopedic surgeons.

METHODS

The American Board of Orthopaedic Surgery Part-II database was queried from 2002 to 2016 for reported open shoulder procedures. The procedures were categorized as follows: arthroplasty, revision arthroplasty, open instability, trauma, and open rotator cuff. We evaluated procedure trends as well as their relationship to surgeon fellowship categorized by Sports, Shoulder/Elbow, Hand, Trauma, and "Other" fellowship as well as no fellowship training. We additionally evaluated complication data as it related to procedure, fellowship category, and volume.

RESULTS

Over the 2002-2016 study period, there were increasing cases of arthroplasty, revision arthroplasty, and trauma (P < .001). There were decreasing cases in open instability and open rotator cuff (P < .001). Those with Sports training reported the largest overall share of open shoulder cases. Those with Shoulder/Elbow training reported an increasing overall share of arthroplasty cases and higher per candidate case numbers. The percentage of early career orthopedic surgeons reporting 5 or more arthroplasty cases was highest among Shoulder/Elbow candidates (P < .001). Across all procedures, those without fellowship training were least likely to report a complication (odds ratio [OR], 0.76; 95% confidence interval, 0.67-0.86; P < .001). Shoulder/Elbow candidates were least likely to report an arthroplasty complication (OR, 0.84, P = .03) as was any surgeon reporting 5 or more arthroplasty cases (OR, 0.81; 95% confidence interval, 0.70-0.94; P = .006).

CONCLUSION

The type and incidence of open shoulder surgery procedures continues to change. Among early career surgeons, those with more specific shoulder training are now performing the majority of arthroplasty-related procedures, and early career volume inversely correlates with complications.

Lower operating volume in shoulder arthroplasty is associated with increased revision rates in the early postoperative period: long-term analysis from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

Improved short-term outcomes have been demonstrated with higher surgical volume in shoulder arthroplasty. There is however, little data regarding long-term outcomes.

METHOD

Revision data from the Australian Orthopaedic Association National Joint Replacement Registry from 2004-2017 was analyzed according to 3 selected surgeon volume thresholds: <10, 10-20, and >20 shoulder arthroplasty cases per surgeon, per year.

RESULTS

There was a significantly higher rate of revision for stemmed total shoulder arthroplasty (TSA) for osteoarthritis (OA) for the <10/yr compared with the >20/yr group for the first 1.5 years only (hazard ratio [HR] 1.36, 95% confidence interval [CI] 1.08-1.71, P = .009). For reverse total shoulder arthroplasty (rTSA) performed for OA, there was a higher revision rate for the <10/yr compared with the >20/yr group for the first 3 months only (HR 2.58, 95% CI 1.67-3.97, P < .001). In rTSA for cuff arthropathy, there was a significantly higher rate of revision for the <10/yr compared with the >20/yr group throughout the follow-up period (HR 1.66, 95% CI 1.21-2.28, P = .001). There was no significant difference for the primary diagnosis of fracture.

CONCLUSION

Lower surgical volume was associated with higher all-cause revision rates in the early postoperative period in TSA and rTSA for OA and throughout the follow-up period in rTSA for cuff arthropathy. Despite increases in the volume of shoulder arthroplasties performed in recent years, more than 78% of surgeons undertake fewer than 10 procedures per year.

Is surgical duration associated with postoperative complications in primary shoulder arthroplasty?

BACKGROUND

Surgical duration is an independent predictor of short-term adverse outcomes after a variety of orthopedic procedures, both arthroscopic and open. However, this association in shoulder arthroplasty remains unclear. The purpose of this study was to identify the association between surgical duration and postoperative complications, as well as increased use of health care resources, after shoulder arthroplasty.

METHODS

Primary shoulder arthroplasty procedures performed from 2005 to 2016 were identified in the American College of Surgeons National Surgical Quality Improvement Program database using Current Procedural Terminology codes. Surgical duration was divided into 3 cohorts: (1) surgical procedures lasting less than 90 minutes, (2) those lasting between 90 and 120 minutes, and (3) those lasting more than 120 minutes. Baseline patient characteristics and outcome variables were compared using bivariate analysis. Outcome variables were compared using multivariate analysis.

RESULTS

Overall, 14,106 patients were identified. Longer surgical duration was significantly associated with younger age, male patients, higher body mass index, and use of general anesthesia, (P < .001 for each), as well as smoking history (P < .39). Relative to operative times shorter than 90 minutes, surgical procedures lasting more than 120 minutes had higher rates of any complication (P = .002), return to the operating room (P = .008), urinary tract infection (P = .02), non-home discharge (P < .001), blood transfusion (P < .001), and unplanned 30-day hospital readmission (P = .03).

CONCLUSION

Increasing surgical duration was associated with a variety of postoperative medical complications and increased use of health care resources including discharge to acute care facilities, blood transfusions, and hospital readmission. These data suggest that surgical duration should be considered for postoperative risk stratification, as well as patient counseling, and may be a surgeon-modifiable risk factor independent of patient risk factors.

Disparities in Cost and Access by Caseload for Arthroscopic Rotator Cuff Repair: An Analysis of 18,616 Cases

Background

Surgeon caseload has been shown to affect both health and economic outcomes in arthroscopic rotator cuff repair. Although previous studies have investigated disparities in access to care, little is known about disparities between low- and high-volume surgeons and facilities.

Purpose

To identify where disparities may exist regarding access to high-volume surgeons and facilities.

Study Design

Cross-sectional study.

Methods

Univariate analysis was performed to analyze differences in the caseload between low- and high-volume surgeons and facilities. Cutoff values were set at 50 cases per year for high-volume surgeons and 125 cases annually for high-volume facilities. Multiple linear regression was then used to develop a cost model incorporating all variables significant under univariate analysis. We collected 18,616 cases with Current Procedural Terminology code 29827 ("arthroscopic rotator cuff repair") from the 2014 Florida State Ambulatory Surgery and Services Databases.

Results

A greater proportion of the caseload for low-volume surgeons and facilities was composed of patients who were of lower socioeconomic status, had government-subsidized insurance, or lived in areas with low-income ZIP codes. Low-volume surgeons and facilities also had higher total charges, higher postoperative admission rates, and lower distal clavicle excision rates (P < .001). In our cost model, a low facility volume significantly increased costs. Subacromial decompression, postoperative admission, distal clavicle excision, male sex, and government-subsidized insurance were all significant factors for increased costs in multivariate cost analysis.

Conclusion

There are disparities in access to high-volume surgeons and facilities for patients undergoing arthroscopic rotator cuff repair in Florida. Patients with a lower socioeconomic status, government-subsidized insurance, and low income all faced decreased access to these high-volume groups. High-volume surgeons and facilities were associated with lower total charges, higher rates of distal clavicle excision, and lower readmission rates. Low-volume facilities added a significant amount of cost, even when controlling for all other significant variables. It is important for providers to be aware of these disparities and work to address them in their own practices.

Relationship between hospital or surgeon volume and outcomes in joint arthroplasty: protocol for a suite of systematic reviews and dose-response meta-analyses

INTRODUCTION

Joint arthroplasty is a particularly complex orthopaedic surgical procedure performed on joints, including the hip, knee, shoulder, ankle, elbow, wrist and even digit joints. Increasing evidence from volume-outcomes research supports the finding that patients undergoing joint arthroplasty in high-volume hospitals or by high-volume surgeons achieve better outcomes, and minimum case load requirements have been established in some areas. However, the relationships between hospital/surgeon volume and outcomes in patients undergoing arthroplasty are not fully understood. Furthermore, whether elective arthroplasty should be restricted to high-volume hospitals or surgeons remains in dispute, and little is known regarding where the thresholds should be set for different types of joint arthroplasties.

METHODS AND ANALYSES

This is a protocol for a suite of systematic reviews and dose-response meta-analyses, which will be amended and updated in conjunction with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols. Electronic databases, including PubMed and Embase, will be searched for observational studies examining the relationship between the hospital or surgeon volume and clinical outcomes in adult patients undergoing primary or revision of joint arthroplasty. We will use records management software for study selection and a predefined standardised file for data extraction and management. Quality will be assessed using the Newcastle-Ottawa Scale, and the meta-analysis, subgroup analysis and sensitivity analysis will be performed using Stata statistical software. Once the volume-outcome relationships are established, we will examine the potential non-linear relationships between hospital/surgeon volume and outcomes and detect whether thresholds or turning points exist.

ETHICS AND DISSEMINATION

Ethical approval is not required, because these studies are based on aggregated published data. The results of this suite of systematic reviews and meta-analyses will be submitted to peer-reviewed journals for publication.

PROSPERO REGISTRATION NUMBER

CRD42017056639.

Fatty infiltration and muscle atrophy of the rotator cuff in stemless total shoulder arthroplasty: a prospective cohort study

BACKGROUND

The influence of preoperative rotator cuff fatty infiltration (FI) and muscle atrophy (MA) on the postoperative outcome of total shoulder arthroplasty (TSA) has only rarely been investigated and reported in the literature. We hypothesized that more FI and MA would be associated with a worse postoperative functional outcome.

METHODS

This prospective cohort study included 63 patients (31 female and 32 male patients; mean age, 71 years [range, 53-89 years; standard deviation, 7 years]) with primary osteoarthritis of the shoulder operated on with anatomic stemless TSA. Preoperatively and at 3 months and 1 year after the operation, the functional outcome (QuickDASH [short version of Disabilities of the Arm, Shoulder and Hand questionnaire] score) and range of motion (ROM) (goniometer) and strength (dynamometer) for abduction at the scapular plane and for external rotation were measured. The degree of preoperative FI and MA was evaluated using computed tomography scans according to the Goutallier classification and Warner classification, respectively, for the supraspinatus and infraspinatus.

RESULTS

We found clinically and statistically significant improvements in functional outcome, strength, and ROM at both 3 months and 1 year of follow-up compared with those preoperatively. The Pearson correlation coefficient (r) showed significant correlations between preoperative supraspinatus and infraspinatus FI and MA and preoperative and 1-year postoperative shoulder abduction and external rotation strength but not ROM. However, we found no influence of the rotator cuff FI and MA on the functional outcome after TSA.

CONCLUSION

We demonstrated a significant correlation between rotator cuff FI and MA and strength but not ROM of the shoulder joint.