Predictors of acromial and scapular stress fracture after reverse shoulder arthroplasty: a study by the ASES Complications of RSA Multicenter Research Group

BACKGROUND

Acromial (ASF) and scapular spine (SSF) stress fractures are well-recognized complications of reverse shoulder arthroplasty (RSA), but much of the current data are derived from single-center or single-implant studies with limited generalizability. This study from the American Shoulder and Elbow Surgeons (ASES) Complications of Reverse Shoulder Arthroplasty Multicenter Research Group determined the incidence of ASF/SSF after RSA and identified preoperative patient characteristics associated with their occurrence.

METHOD

Fifteen institutions including 21 ASES members across the United States participated in this study. Patients undergoing either primary or revision RSA between January 2013 and June 2019 with a minimum 3-month follow-up were included. All definitions and inclusion criteria were determined using the Delphi method, an iterative survey process involving all primary investigators. Consensus was achieved when at least 75% of investigators agreed on each aspect of the study protocol. Only symptomatic ASF/SSF diagnosed by radiograph or computed tomography were considered. Multivariable logistic regression was performed to identify factors associated with ASF/SSF development.

RESULTS

We identified 6755 RSAs with an average follow-up of 19.8 months (range, 3-94). The total stress fracture incidence rate was 3.9% (n = 264), of which 3.0% (n = 200) were ASF and 0.9% (n = 64) were SSF. Fractures occurred at an average 8.2 months (0-64) following RSA with 21.2% (n = 56) following a trauma. Patient-related factors independently predictive of ASF were chronic dislocation (odds ratio [OR] 3.67, P = .04), massive rotator cuff tear without arthritis (OR 2.51, P < .01), rotator cuff arthropathy (OR 2.14, P < .01), self-reported osteoporosis (OR 2.21, P < .01), inflammatory arthritis (OR 2.18, P < .01), female sex (OR 1.51, P = .02), and older age (OR 1.02 per 1-year increase, P = .02). Factors independently associated with the development of SSF included osteoporosis (OR 2.63, P < .01), female sex (OR 2.34, P = .01), rotator cuff arthropathy (OR 2.12, P = .03), and inflammatory arthritis (OR 2.05, P = .03).

CONCLUSION

About 1 in 26 patients undergoing RSA will develop a symptomatic ASF or SSF, more frequently within the first year of surgery. Our results indicate that severe rotator cuff disease may play an important role in the occurrence of stress fractures following RSA. This information can be used to counsel patients about potential setbacks in recovery, especially among older women with suboptimal bone health. Strategies for prevention of ASF and SSF in these at-risk patients warrant further study. A follow-up study evaluating the impact of prosthetic factors on the incidence rates of ASF and SSF may prove highly valuable in the decision-making process.

A smart decision: smartphone use for operative data collection in arthroscopic shoulder instability surgery

OBJECTIVE

This study tested validity, accuracy, and efficiency of the Orthopaedic Minimal Data Set Episode of Care (OME) compared with traditional operative report in arthroscopic surgery for shoulder instability. As of November 2017, OME had successfully captured baseline data on 97% of 18 700 eligible cases.

MATERIALS AND METHODS

This study analyzes 100 cases entered into OME through smartphones by 12 surgeons at an institution from February to October 2015. A blinded reviewer extracted the same variables from operative report into a separate database. Completion rates and agreement were compared. They were assessed using raw percentages and McNemar's test (with continuity correction). Agreement between nominal variables was assessed by unweighted Cohen's kappa and a concordance correlation coefficient measured agreement between continuous variables. Efficiency was assessed by median time to complete.

RESULTS

Of 37 variables, OME demonstrated equal or higher completion rates for all but 1 and had significantly higher capture rates for 49% (n = 18; P < .05). Of 33 nominal variables, raw proportional agreement was ≥0.90 for 76% (n = 25). Raw proportional agreement was perfect for 15% (n = 5); no agreement statistic could be calculated due to a single variable in operative note and OME. Calculated agreement statistic was substantial or better (κ > 0.61) for 51% (n = 17) for the 33 nominal variables. All continuous variables assessed (n = 4) demonstrated poor agreement (concordance correlation coefficient <0.90). Median time for completing OME was 103.5 (interquartile range, 80.5-151) seconds.

CONCLUSIONS

The OME smartphone data capture system routinely captured more data than operative report and demonstrated acceptable agreement for nearly all nominal variables, yet took <2 minutes to complete on average.

Proceedings from the 2018 International Consensus Meeting on Orthopedic Infections: the definition of periprosthetic shoulder infection

Research studies with evidence impacting clinical practice have used disparate definitions of shoulder periprosthetic joint infection, likely leading to variable and inconsistent conclusions about its diagnosis and management. In an effort to establish uniform guidelines for clinical decision making and research reporting, a clear definition of periprosthetic shoulder infection was established at the 2018 International Consensus Meeting on Orthopedic Infections.

Humeral Head Shape in Native and Prosthetic Joint Replacement

Background

Nonspherical prosthetic humeral head designs have become increasingly popular as they better approximate the native shoulder anatomy and biomechanical properties and is supported by the existing literature. It remains to be seen how this will impact postoperative outcomes for total shoulder arthroplasty providing a justification for this review.

Methods

A review and synthesis of the literature on the subject of joint replacement in the native and prosthetic humeral head was performed.

Results

Our review encompasses the anatomical, biomechanical, and finite element data present in the literature for native and prosthetic joint replacement. They describe the native humeral head as more elliptical (nonspherical) than circular (spherical) and that nonspherical prosthetics more closely approximate glenohumeral kinematic properties.

Conclusion

A nonspherical prosthetic may influence long-term clinical outcomes in hemiarthroplasty and anatomic total shoulder arthroplasty though further research in this area is necessary.

Three-dimensional preoperative planning software and a novel information transfer technology improve glenoid component positioning

BACKGROUND

We hypothesized that a novel surgical method, in which three-dimensional (3-D) preoperative planning software is generated to create a patient-specific surgical model that is used with a reusable and adjustable tool, could substantially improve the positioning accuracy of the glenoid guide pin used in total shoulder arthroplasty. We tested this method using bone models from patients with shoulder pathology and compared the results with those achieved using surgical methods representing the current standard of care.

METHODS

Three surgeons with a variety of surgical experience placed a guide pin in nine bone models from patients with a variety of glenohumeral arthritis severity using (1) standard instrumentation alone, (2) standard instrumentation and 3-D preoperative surgical planning, and (3) the reusable transfer device and 3-D preoperative surgical planning. A postoperative 3-D computed tomography scan of the bone model was made and registered to the preoperative plan, and the differences between the actual and planned pin locations and trajectories were measured.

RESULTS

Use of the standard instrumentation combined with 3-D preoperative planning software improved guide pin positioning compared with standard instrumentation and preoperative planning using 2-D imaging. The accuracy of pin positioning increased by 4.5° ± 1.0° in version (p &lt; 0.001), 3.3° ± 1.3° in inclination (p = 0.013), and 0.4 ± 0.2 mm in location (p = 0.042). Use of the adjustable and reusable device and the 3-D software improved pin positioning by a further 3.7° ± 0.9° in version, 8.1° ± 1.2° in inclination, and 1.2 ± 0.2 mm in location (p &lt; 0.001 for all) compared with standard instrumentation and the 3-D software; the improvement compared with use of standard instrumentation with 2-D imaging was 8.2° ± 0.9° in version, 11.4° ± 1.2° in inclination, and 1.7 ± 0.2 mm in location (p &lt; 0.001 for all).

CONCLUSIONS

Use of 3-D preoperative planning and use of the patient-specific bone model and transfer device both improved the positioning accuracy of the pin used to guide placement of the glenoid component in total shoulder arthroplasty.

CLINICAL RELEVANCE

Proper positioning of the glenoid component would be expected to improve the function and durability of the joint replacement.

Fibrous dysplasia

Fibrous dysplasia is a developmental disorder of bone that can present in a monostotic or polyostotic form. Primarily affecting adolescents and young adults, it accounts for 7% of benign bone tumors. Many of the asymptomatic lesions are found incidentally; the remainder present with symptoms of swelling, deformity, or pain. Fibrous dysplasia has been associated with multiple endocrine and nonendocrine disorders and with McCune-Albright and Mazabraud's syndromes. The etiology remains unclear, but molecular biology suggests a mutation in the G(s)alpha subunit and activation of c-fos and other proto-oncogenes. Fibrous dysplasia has a characteristic radiographic appearance. Most cases do not require intervention, but those that do usually are managed surgically with curettage, bone grafting, and, in some cases, internal fixation. When some intervention is necessary but surgery is not practical, treatment is with bisphosphonates. The prognosis generally is good, although poor outcomes are more frequent in younger patients and in those with polyostotic forms of the disease. The risk of malignant transformation is low.