The epidemiology of acromioclavicular joint excision

In Vivo Analysis of Acromioclavicular Kinematics and Distance During Multiplanar Humeral Elevation

BACKGROUND

Knowledge of acromioclavicular (AC) joint kinematics and distance may provide insight into the biomechanical function and development of new treatment methods. However, accurate data on in vivo AC kinematics and distance between the clavicle and acromion remain unknown.

PURPOSE/HYPOTHESIS

The purpose of this study was to investigate 3-dimensional AC kinematics and distance during arm elevation in abduction, scaption, and forward flexion in a healthy population. It was hypothesized that AC kinematics and distance would vary with the elevation angle and plane of the arm.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 19 shoulders of healthy participants were enrolled. AC kinematics and distance were investigated with a combined dual fluoroscopic imaging system and computed tomography. Rotation and translation of the AC joint were calculated. The AC distance was measured as the minimum distance between the medial border of the acromion and the articular surface of the distal clavicle (ASDC). The minimum distance point (MDP) ratio was defined as the length between the MDP and the posterior edge of the ASDC divided by the anterior-posterior length of the ASDC. AC kinematics and distance between different elevation planes and angles were compared.

RESULTS

Progressive internal rotation, upward rotation, and posterior tilt of the AC joint were observed in all elevation planes. The scapula rotated more upward relative to the clavicle in abduction than in scaption (P = .002) and flexion (P = .005). The arm elevation angle significantly affected translation of the AC joint. The acromion translated more laterally and more posteriorly in scaption than in abduction (P < .001). The AC distance decreased from the initial position to 75° in all planes and was significantly greater in flexion (P < .001). The MDP ratio significantly increased with the elevation angle (P < .001).

CONCLUSION

Progressive rotation and significant translation of the AC joint were observed in different elevation planes. The AC distance decreased with the elevation angle from the initial position to 75°. The minimum distance between the ASDC and the medial border of the acromion moved anteriorly as the shoulder elevation angle increased.

CLINICAL RELEVANCE

These results could serve as benchmark data for future studies aiming to improve the surgical treatment of AC joint abnormalities to restore optimal function.

Morphology of the acromioclavicular-joint score (MAC)

INTRODUCTION

To date there is no generally accepted specific definition or classification of acromioclavicular (AC) joint osteoarthritis. The aim of this study is to analyze morphological parameters using magnetic resonance imaging (MRI) and to develop a scoring system as a basis for decision making to perform an AC-joint resection.

MATERIALS AND METHODS

In a retrospective-monocentric matched pair study, healthy and affected subjects were investigated using T2 MRI scans in the transverse plane. There were two groups, group 1 (n = 151) included healthy asymptomatic adults with no history of trauma. In group 2, we included n = 99 patients with symptomatic AC joints, who underwent arthroscopic AC-joint resection. The central and posterior joint space width and the AC angle were measured. Morphological changes such as cartilage degeneration, cysts and bone edema were noted. Malalignment of the joint was defined as: posterior joint space width < 2 mm in conjunction with an AC angle > 12°. A scoring system consisting of the measured morphologic factors was developed.

RESULTS

Symptomatic and asymptomatic patients showed significant differences in all measured items. We observed a significant difference in the MAC score for symptomatic and asymptomatic patients (mean 10.4 vs. 20.6, p = 0.0001). The ROC (receiver operator characteristic) analysis showed an excellent AUC of 0.899 (p = 0.001). The sensitivity of the MAC score was 0.81 and the specificity 0.86. The MAC score shows a significant moderate correlation with age (r = 0.358; p = 0.001). The correlation of age and the development of symptoms was only weak (r = 0.22, p = 0.001). Symptomatic patients showed significantly more frequent malalignment compared to asymptomatic patients (p = 0.001), but the positive predictive value that a patient with malalignment is also symptomatic is only 55%.

CONCLUSION

Patients with symptomatic AC joints showed a typical pattern of morphological changes on axial MRI scans with early posterior contact of the joint surfaces, reduction of joint space and malalignment as the basis for the development of a scoring system. The MAC score shows excellent test characteristics, and therefore, proved to be both an appropriate guidance for clinical practice as well as an excellent tool for comparative studies and is superior to the assessment of malalignment alone.

LEVEL OF EVIDENCE

Level IV, retrospective diagnostic study.

Anatomical variants of the acromioclavicular joint influence its visibility in the standard MRI protocol in patients aged 18-31 years

Purpose

Visualization of a structure in orthogonal planes is essential for correct radiological assessment. The aim was to assess the utility of the standard MRI protocol for the shoulder in the assessment of the acromioclavicular joint (ACJ).

Methods

A total of 204 MRI scans of the shoulder were re-reviewed. Visibility of the ACJ in orthogonal planes was assessed, and the type of acromion and the angle between the ACJ and the glenoid cavity were assessed by two observers.

Results

Agreement in the assessment of ACJ visibility was moderate to substantial. The ACJ was visible in the three anatomical views in 48% (confidence interval [CI] 95% = [41–54%]) of the examinations, and no significant difference regarding gender or age was noticed. The mean angle between the ACJ and the glenoid cavity was 41.12 deg. CI95% = (39.72, 42.53) in the axial plane, 33.39 deg. CI95% = (31.33, 35.45) in the coronal plane and 52.49 deg. CI95% = (50.10, 54.86) in the sagittal plane. When the ACJ was visible in the sagittal and axial planes, significant differences were noticed in the remaining planes (p < .05).

Conclusion

Anatomical variations of the ACJ influence its visibility in the standard MRI protocol for examining the shoulder, making this protocol insufficient for ACJ assessment in the examined population.

Shoulder structure and function: The impact of osteoarthritis and rehabilitation strategies

STUDY DESIGN

Invited review.

BACKGROUND

Shoulder osteoarthritis can result in significant functional deficits. To improve diagnosis and treatment, we must better understand the impact of osteoarthritis on shoulder biomechanics and the known mechanical benefits of currently available treatments.

PURPOSE

The purpose of this paper is to present up-to-date data on the effects of osteoarthritis and rehabilitation on the biomechanical parameters contributing to shoulder function. With this goal, we also reviewed the anatomy and the ranges of motion of the shoulder.

METHODS

A search of electronic databases was conducted. All study designs were included to inform this qualitative, narrative literature review.

RESULTS

This review describes the biomechanics of the shoulder, the impact of osteoarthritis on shoulder function, and the treatment of shoulder osteoarthritis with an emphasis on rehabilitation.

CONCLUSIONS

The shoulder is important for the completion of activities of daily living, and osteoarthritis of the shoulder can significantly reduce shoulder motion and arm function. Although shoulder rehabilitation is an integral treatment modality to improve pain and function in shoulder osteoarthritis, few high-quality studies have investigated the effects and benefits of shoulder physical and occupational therapies. To advance the fields of therapy and rehabilitation, future studies investigating the effects of therapy intensity, therapy duration, and the relative benefits of therapy subtypes on shoulder biomechanics and function are necessary.

Diabetes is an independent risk factor for infection after non-arthroplasty shoulder surgery: a national database study

OBJECTIVES

Diabetes has been associated with poor healing and prior literature has shown worse functional outcomes in diabetic patients undergoing both open and arthroscopic shoulder surgery. However, the effects of diabetes on perioperative complications for patients undergoing non-arthroplasty type shoulder procedures are not well defined. The purpose of this study was to analyze the effects of diabetes on 30-day complications following non-arthroplasty shoulder surgery.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program was used to identify patients who underwent open and arthroscopic shoulder procedures (excluding arthroplasty) from 2011 to 2018. Diabetic patients were identified and compared to a non-diabetic cohort. Demographic data and postoperative complications within 30 days were analyzed. Multivariable regression was used to determine the effect of diabetes on shoulder surgery.

RESULTS

We identified 99,970 patients who underwent shoulder surgery in our cohort and 13.9% (13,857 patients) of these patients were diabetics. Within the diabetic cohort, 4,394 (31.7%) were insulin dependent. Diabetics were more likely to be older, female, and have a higher body mass index (P < 0.01). Diabetics had a higher rate of associated medial comorbidities (P < 0.05). Diabetics were less likely to be smokers and on average had shorter surgeries (P < 0.05). Univariate analysis showed that diabetes was associated with increased risk for infectious and other major and minor complications; however, multivariate regression revealed that diabetes was only independently associated with infection (OR 1.33, P = 0.38).

CONCLUSION

While diabetes is associated with increased likelihood of infection following shoulder surgery, absent commonly associated comorbidities, they are not at increased risk for other 30-day postoperative complications.