Evaluating Bone Loss in Anterior Shoulder Instability

Accuracy and Consistency of 3-Dimensional Magnetic Resonance Imaging Is Comparable With 3-Dimensional Computed Tomography in Assessing Glenohumeral Instability: A Systematic Review

PURPOSE

To compare the accuracy of 3-dimensional (3D) magnetic resonance imaging (MRI) with that of 3D computed tomography (CT) in evaluating glenoid bone loss (GBL).

METHODS

This review aligned with Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. PubMed, the Cochrane Library, Embase, and Web of Science were obtained from data inception to August 28, 2023. The search term "glenoid bone loss" was extracted and analyzed via stringent inclusion and exclusion criteria. The Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 combined with the QUADAS-Comparative to assess the heterogeneity of included studies.

RESULTS

A total of 1,589 related studies were retrieved, and 10 studies were finally included, of which a total of 143 shoulders were evaluated. The index test in QUADAS-Comparative was low risk in 9 studies. 3D MRI measurements of GBL were primarily best-fit circles (n = 9). In both clinical and cadaveric studies, the mean percentages of GBL measured by 3D MRI were 0.38% to 2.19% and 0.25% to 6.1% when compared with 3D CT and standard reference values, respectively. Intraclass correlation coefficient agreement greater than 0.9 between GBL percentages measured by 3D CT and 3D MRI. 3D MRI also could accurately measure glenoid width, glenoid height, humeral head width, and height. 3D MRI reconstruction time was similar to that of 3D CT, which was mainly 10 to 15 minutes.

CONCLUSIONS

In both clinical and cadaveric studies, compared with 3D CT, 3D MRI is accurate and consistent in assessing glenohumeral bone, especially in measuring GBL, and the reconstruction time of 3D MRI is similar to 3D CT.

LEVEL OF EVIDENCE

Level Ⅲ, systematic review of Level Ⅱ-Ⅲ studies.

Beyond guesswork: how accurate are surgeons at determining the degree of glenoid bone loss in instability surgery?

Background

Accurate measurement of glenoid bone loss (GBL) is critical to preoperative planning in cases of recurrent shoulder instability. The concept of critical bone loss has been established with a value of GBL >13.5% being associated with higher failure rate following arthroscopic Bankart Repair. Advanced imaging, such as magnetic resonance imaging (MRI) scans, can be used to quantify GBL prior to surgery using the best-fit circle technique. Surgeons have traditionally relied on visual inspection of the MRI scan preoperatively or on visual inspection of the glenoid at the time of arthroscopy to determine whether GBL is present. The purpose of this study is to determine if 3 fellowship-trained shoulder surgeons could adequately quantify GBL without using best-fit circle measurements on MRI.

Methods

A retrospective review was performed which included 122 patients over an 8-year period that had an arthroscopic Bankart repair performed by 3 fellowship-trained surgeons. In all patients, preoperative MRI scans were retrospectively measured using best-fit circle technique to determine true GBL and compare that to the surgeons' preoperative and intraoperative estimation of GBL.

Results

GBL was correctly identified in only 36% (18/50) of patients when the preoperative best-fit circle measurements were not made. Critical bone loss was missed in 9.8% (12/122) of patients in the study group. The estimated mean bone loss in that group by visual inspection was 11.3% compared to 16% true bone loss measured on MRI. Even in the 18 patients with some identified bone loss prior to surgery, critical bone loss was missed in 6 patients when using visual inspection of the MRI or intraoperative inspection alone.

Conclusion

Simple visual inspection of glenoid images on MRI scan and visual inspection of the glenoid at the time of surgery are inaccurate in determining the true extent of GBL especially in cases of subtle bone deficiency. Preoperative planning is dependent on the exact degree of bone deficiency and measurement on the MRI scan using the best-fit circle technique is recommended in all cases of instability surgery.

Current Concepts in the Measurement of Glenohumeral Bone Loss

PURPOSE

The extent of glenohumeral bone loss seen in anterior shoulder dislocations plays a major role in guiding surgical management of these patients. The need for accurate and reliable preoperative assessment of bone loss on imaging studies is therefore of paramount importance to orthopedic surgeons. This article will focus on the tools that are available to clinicians for quantifying glenoid bone loss with a focus on emerging trends and research in order to describe current practices.

RECENT FINDINGS

Recent evidence supports the use of 3D CT as the most optimal method for quantifying bone loss on the glenoid and humerus. New trends in the use of 3D and ZTE MRI represent exciting alternatives to CT imaging, although they are not widely used and require further investigation. Contemporary thinking surrounding the glenoid track concept and the symbiotic relationship between glenoid and humeral bone loss on shoulder stability has transformed our understanding of these lesions and has inspired a new focus of study for radiologists and orthopedist alike. Although a number of different advanced imaging modalities are utilized to detect and quantify glenohumeral bone loss in practice, the current literature supports 3D CT imaging to provide the most reliable and accurate assessments. The emergence of the glenoid track concept for glenoid and humeral head bone loss has inspired a new area of study for researchers that presents exciting opportunities for the development of a deeper understanding of glenohumeral instability in the future. Ultimately, however, the heterogeneity of literature, which speaks to the diverse practices that exist across the world, limits any firm conclusions from being drawn.

Anatomic Osteochondral Allograft Reconstruction for Concomitant Large Hill-Sachs and Reverse Hill-Sachs Lesions

Glenohumeral instability causing bipolar bone loss is increasingly being recognized and treated to minimize recurrence. Large Hill-Sachs and reverse Hill-Sachs lesions of the humerus must be addressed at the time of surgery to prevent recurrent dislocations and restore the native anatomic track. For patients with epilepsy, locked dislocations may create defects that must be addressed with bony procedures, including osteochondral allograft reconstruction as soft-tissue remplissage may not adequately addresses the magnitude of the bone loss. Osteochondral allografts have been successfully used to address bony defects ranging from 20% to 30% of humeral bone loss whereas shoulder arthroplasty is indicated for larger defects where the native anatomy can no longer be restored. In this Technical Note, we present a technique to address concomitant large Hill-Sachs and reverse Hill-Sachs lesions.

Early Treatment of Shoulder Pathology Is Necessary but Not Enough Is Being Performed

Delayed treatment of shoulder instability results in bone loss requiring more-complicated surgery, in turn resulting in less-optimal outcomes. Similarly, delayed treatment of repairable rotator cuff tears results in irreparable tears requiring more-complicated surgery and resulting in less-optimal outcomes. Delayed treatment of shoulder pathology is a problem. Solutions include education and research investigation.