Coracoid impingement: current concepts

Alteration in coracohumeral ligament and distance in people with symptoms of subcoracoid impingement

BACKGROUND

Differentiation between subacromial impingement versus subcoracoid impingement are important for the treatment target. We evaluated the correlations between coracohumeral ligament (CHL) thickness and distance (CHD) and characterized the CHL and subscapularis (SSC) in subcoracoid impingement subjects.

METHODS

An observational, cross-sectional study was carried out. Twenty subcoracoid impingement subjects and age/gender matched controls were assessed in 4 different shoulder positions by ultrasonography.

RESULTS

Moderate correlations between CHL thickness with CHD (r = 0.455 in neutral rotation, p = 0.044; r = 0.483 in interior rotation, p = 0.031) were found in subacromial subjects. Subcoracoid impingement subjects had greater CHL thickness (difference = 0.3 mm, effect size = 0.85, p = 0.006), SSC tendon thickness (difference = 0.7 mm, effect size = 0.92, p = 0.01) and SSC/CHD occupation ratio (difference = 8%, effect size = 0.95, p = 0.005) compared with the control.

CONCLUSIONS

Coracohumeral distance is related to ligament thickness, especially in subacromial impingement subjects. Increased coracohumeral ligament and subscapularis thickness as well as decreased subscapularis/coracohumeral distance occupation ratio are characterized in subcoracoid impingement subjects. These quantitative measurements can be useful in identifying patients at risk of subcoracoid impingement from subacromial impingement.

Bilateral coracohumeral distance discrepancy is associated with subscapularis tear in rotator cuff rupture patients

PURPOSE

To describe the bilateral coracohumeral morphological discrepancy in rotator cuff rupture patients with and without subscapularis (SSC) involvement and to investigate its association with SSC tears.

METHODS

Two hundred and thirteen consecutive patients who were scheduled to have arthroscopic rotator cuff repair were prospectively enrolled in the current study. Patients with acute traumatic rotator cuff rupture, glenohumeral osteoarthritis, bilateral rotator cuff rupture, recurrent shoulder instability, systemic inflammatory disease, and previous shoulder surgery history were excluded. Coracohumeral distance (CHD), coracoid overlap (CO), lesser tuberosity index (LTI) and acromiohumeral interval (AHI) were measured bilaterally using CT scans. Based on arthroscopic findings, patients were included in either the SSC tear group (n = 72) or the control group (n = 141).

RESULTS

In the SSC tear group, the affected shoulder possessed a significantly smaller CHD [95% confidence interval (CI) 6.1-7.2 vs. 7.2-8.0 mm, p < 0.0001], larger LTI (95% CI 9.4-9.9 vs. 9.0-9.6 mm, p < 0.0001), and smaller AHI (95% CI 5.0-5.5 vs. 7.1-7.5 mm, p < 0.0001) than the contralateral normal shoulder. In the control group, there was no significant difference between bilateral CHD and CO, and the AHI bilateral discrepancy was less distinct. CO did not differ significantly in the bilateral comparison in either group. Among all evaluated parameters, bilateral CHD discrepancy was the best predictor of SSC tears, with an area under the curve (AUC) of 0.882. A cutoff value of 0.5 mm had a sensitivity of 76.4% and specificity of 99.3% for SSC tears.

CONCLUSION

The CHD values are significantly different between affected and contralateral shoulders in SSC tear patients. Bilateral CHD discrepancy is closely associated with subcoracoid impingement and SSC tears, and its presence warrants specific intraoperative SSC inspection.

LEVEL OF EVIDENCE

Level II.

Influence of coracoid anatomy on the location of glenoid rim defects in anterior shoulder instability: 3D CT-scan evaluation of 51 patients

PURPOSE

Glenoid bony lesions play a role in approximately half of anterior shoulder instability cases. The purpose of this study is to see if the anatomy of the coracoid affects the location of glenoid rim defects. We hypothesized that a prominent coracoid (lower and lateral) would be more likely to cause an anterior-inferior glenoid lesion, and a less prominent coracoid more prone to cause an anterior lesion. The null hypothesis being the absence of correlation.

METHODS

Fifty-one shoulder CT-scans from a prospective database, with 3D reconstruction, were analyzed. The position of glenoid lesions was identified using the validated clock method, identifying the beginning and end time. The size of bony glenoid defects was calculated using the validated glenoid ratio method. The position of the coracoid tip was measured in three orthogonal planes.

RESULTS

Analysis included 25 right shoulders and 26 left shoulders in seven females and 41 males. The vertical position of the coracoid tip relative to the top of the glenoid was highly correlated to the location of the glenoid defect on the profile view (r = -0.625; 95% CI 0.423-0.768; p = 0.001). Thus, higher coracoids were associated with anterior lesions, while lower coracoids were associated with anterior-inferior lesions. A more laterally prominent coracoid was also correlated with anterior-inferior lesions (r = 0.433; 95% CI 0.179-0.633; p = 0.002).

CONCLUSION

This study shows that coracoid anatomy affects the location of bony Bankart defects in anterior shoulder instability. Lower and laterally prominent coracoids are associated with anterior-inferior lesions. This variation in anatomy should be considered during pre-op planning for surgeries involving bone graft.

LEVEL OF EVIDENCE

Level 4 basic science.

Editorial Commentary: Arthroscopic Subscapularis Repair: Bridging Successful Tendon Healing and Improved Patient Outcomes

Open repair has been regarded as the gold standard for the treatment of subscapularis tendon tears. However, recent studies on newer arthroscopic techniques and published results of arthroscopic repair have shown promising results. As such, there exists a growing interest in understanding the best fixation technique to obtain successful functional and patient-reported clinical outcomes. While the literature shows superior outcomes after double-row repair for posterosuperior rotator cuff tears compared with single-row repair, the evidence is inconclusive for subscapularis tears. We believe that arthroscopic double-row transosseous equivalent repair of full-thickness subscapularis tears leads to superior clinical outcomes with higher healing rates and will become the standard of care in the future.

[Impingement syndromes of the shoulder]

In addition to tears of the rotator cuff, isolated impingement syndrome of the shoulder is the most common diagnosis in shoulder disorders. This is of high relevance in orthopedic sports medicine. In fact, impingement of the shoulder is not the diagnosis but rather a symptom of a functional or even a structural pathology. Detailed knowledge about the different types of impingement and the underlying causes is essential to provide adequate treatment. Primarily, impingement of the shoulder should be treated nonoperatively. However, if there is no clinical improve despite adequate conservative treatment, there is usually a structural pathology which cannot be adequately compensated for and surgical treatment may be necessary. In the case of severe structural pathologies, such as a full-thickness tear of the rotator cuff, a subsequent surgical treatment may be indicated.

Dynamic ultrasonography of the shoulder

Ultrasonography (US) is a useful diagnostic method that can be easily applied to identify the cause of shoulder pain. Its low cost, excellent diagnostic accuracy, and capability for dynamic evaluation are also advantages. To assess all possible causes of shoulder pain, it is better to follow a standardized protocol and to perform a comprehensive evaluation of the shoulder than to conduct a focused examination. Moreover, a proper dynamic study can enhance the diagnostic quality of US, especially when the pathology is not revealed by a static evaluation. The purpose of this article is to review the common indications for dynamic US of the shoulder, and to present the basic techniques and characteristic US findings.

Arthroscopic management of lesser tuberosity osteochondroma causing impingement and subscapularis tear of the shoulder

Although the proximal humerus is a common site of osteochondroma, osteochondroma arising from the lesser tuberosity of the proximal humerus is rare. Because of the anatomy of the shoulder, mechanical impingement can occur via direct contact of the protruding lesser tuberosity against the glenoid rim or coracoid. In younger patients, this may cause isolated tearing of the subscapularis. In this study, is presented a rare case of osteochondroma on the lesser tuberosity that caused a subscapularis tear after shoulder impingement in a 34-year-old male. This case was managed using an arthroscopic approach. One year after the surgery, the patient had recovered a normal range of motion, with the resolution of impingement symptoms and the tearing of the subscapularis. Level of evidence IV.

Measurement of Coracohumeral Distance in 3 Shoulder Positions Using Dynamic Ultrasonography: Correlation With Subscapularis Tear

PURPOSE

To detect differences between the values of dynamic coracohumeral distance (CHD) measured using ultrasonography (USG) in different shoulder rotations and to investigate its correlation with subscapularis tear.

METHODS

We prospectively enrolled consecutive patients (n = 168) who were scheduled to have arthroscopic rotator cuff repair. Patients with a history of previous shoulder surgery or shoulder fracture and patients with external rotation less than 30° were excluded from the study. Dynamic CHD was measured using USG in 3 different shoulder positions: external rotation, neutral and internal rotation. We evaluated the intrarater reliability with 3 times repetition of measurement. Patients were divided into 1 of 3 groups according to arthroscopic findings: intact subscapularis, partial-thickness tear, and full-thickness tear of the subscapularis. The control group (n = 23) included patients without rotator cuff tears from the outpatient clinic. Subgroup analysis-according to the presence of dynamic subcoracoid stenosis, defined as a CHD less than 6 mm measured in internal rotation-was performed to find the clinical effect of dynamic subcoracoid stenosis.

RESULTS

A partial-thickness tear of the subscapularis tendon was present in 60 patients (35.7%) and a full-thickness tear in 26 patients (15.4%) among 168 patients. The CHD was maximum in external rotation and the narrowest in internal rotation. There were no statistical differences in the CHDs between groups with different subscapularis tear status. According to the presence of dynamic subcoracoid stenosis, patients with dynamic subcoracoid stenosis had a significantly higher incidence of partial-thickness subscapularis tear than those without stenosis (P = .022).

CONCLUSIONS

The CHD values were narrowest in shoulder internal rotation, which is thought to be the pathogenic position. We could not confirm the correlation between CHD and subscapularis tear. However, patients who have dynamic subcoracoid stenosis had significantly higher incidence of subscapularis tear than others without dynamic stenosis.

LEVEL OF EVIDENCE

Level II, prospective prognostic cohort study.

Distance between rotator cuff footprints and the acromion, coracoacromial ligament, and coracoid process during dynamic arm elevations: Preliminary observations

BACKGROUND

The objective of this study was to provide preliminary measures of the distance between the supraspinatus, infraspinatus, and subscapularis footprints and the acromion, coracoacromial ligament, and coracoid process, during dynamic arm elevations through the entire range-of-motion.

METHODS

Two healthy men performed maximum adduction, flexion, abduction, and extension with the arm internally, neutrally, and externally rotated. The distance between each rotator cuff footprint and the acromion, coracoacromial ligament, and coracoid process was measured from glenohumeral kinematics obtained from markers fitted to intracortical pins combined with the scapular and humeral 3D geometry obtained from CT-scan.

RESULTS

All footprints moved to be less than 10 mm to the acromion, coracoacromial ligament and coracoid process. They got closer to the acromion than to the other parts of the coracoacromial arch. The acromion-supraspinatus and acromion-infraspinatus distances were minimal during abduction and flexion. The acromion-subscapularis distance was minimal when the arm was in external and neutral rotation during both adduction and flexion.

CONCLUSIONS

The present study provides benchmark results of the distance between the rotator cuff footprints and the coracoacromial arch that may guide future clinical research. Pressure transducers should be positioned throughout the coracoacromial arch to provide comprehensive assessment of the compression undergone by the rotator cuff tendons. Common shoulder examination tests, that require flexion and internal rotation movements, may be refined since the supraspinatus footprint was the closest to the coracoacromial arch during abduction. Larger scale investigations may be needed to identify more accurate shoulder examination tests.

Soft tissue tumour causing coracoid impingement syndrome

Coracoid impingement syndrome results from subscapularis tendon entrapment between the humerus and the coracoid. This syndrome is an uncommon cause of shoulder pain that has many different aetiologies. Although synovial cysts have been reported as cause of coracoid impingement at this level, solid tumoural lesions are a rare cause of symptoms in this location. Two cases of benign soft tissue solid tumours are presented. Both patients developed symptoms compatible with coracoid impingement syndrome. The lesions were fully resected under arthroscopic visualization. Both patients had complete resolution of the symptoms and are asymptomatic at 2-year follow-up. Arthroscopic removal of benign soft tissue tumours that cause coracoid impingement syndrome has good results.

Coracoacromial ligament section under ultrasonographic control: a cadaveric study on 20 cases

INTRODUCTION

The coracoacromial ligament is a complex anatomical structure involved in the development of subacromial impingement; treatment is founded on sectioning the ligament, with or without associated arthroscopic acromioplasty and debridement.

HYPOTHESIS

Complete coracoacromial ligament section can be performed under ultrasound, without lesion to surrounding structures.

MATERIALS AND METHODS

The coracoacromial ligament was sectioned on the coracoid side, under ultrasound navigation, in 10 cadavers donated to science: i.e. 20 shoulders. After ultrasound location of the shoulder structures, sectioning was performed with a skin incision at the level of the deltopectoral sulcus. Secondary surgical control checked conservation of the acromial branch of the thoracoacromial artery, and the quality of the procedure.

RESULTS

Mean surgery duration was 18.5 minutes (±5 min). Seventeen sections were complete (85%). Artery location was hampered by the impossibility of using Doppler on these cadavers, yet even so there were only 2 vascular lesions. There were no accidental rotator cuff or cartilaginous lesions.

CONCLUSION

This relatively non-invasive technique is quick and less heavy than open surgery, opening up new treatment perspectives. It could be indicated in coracoid and subacromial impingement before opting for surgery, or as a complement to surgery. It does, however, involve a learning curve and requires solid ultrasound skills.

Coracohumeral Distances and Correlation to Arm Rotation: An In Vivo 3-Dimensional Biplane Fluoroscopy Study

Background:

Reduced coracohumeral distances have been reported to be associated with anterior shoulder disorders such as subscapularis tears, biceps tendon injuries, and leading edge supraspinatus tears.

Purpose:

To determine the variability in coracohumeral distance as a function of arm rotation in healthy male subjects. The null hypothesis was that no differences in coracohumeral distance would exist with respect to arm rotation.

Study Design:

Descriptive laboratory study.

Methods:

A total of 9 male participants who had full range of motion, strength, and no prior surgery or symptoms in their tested shoulders were enrolled in this institutional review board–approved study. Computed tomography scans of the shoulder were obtained for each subject. A dynamic biplane fluoroscopy system recorded internal and external shoulder rotation with the arm held in the neutral position. Three-dimensional reconstructions of each motion were generated, and the coracohumeral distance and coracoid index (lateral extension of the coracoid) were measured.

Results:

The mean coracohumeral distance in neutral rotation was 12.7 ± 2.1 mm. A significantly shorter minimum coracohumeral distance of 10.6 ± 1.8 mm was achieved (P = .001) at a mean glenohumeral joint internal rotation angle of 36.6° ± 19.2°. This corresponded to a reduction in coracohumeral distance of 16.4% (range, 6.6%-29.8%). The mean coracoid index was 14.2 ± 6.8 mm. A moderate correlation (R = −0.75) existed between the coracohumeral distance and coracoid index.

Conclusion:

Coracohumeral distance was reduced during internal rotation. Decreased coracohumeral distance was correlated with larger coracoid indices.

Clinical Relevance:

This study provides a reference value for coracohumeral distance in the healthy male population. Knowledge of how coracohumeral distance varies over the range of arm internal-external rotation may improve the clinical diagnosis and treatment plan for patients with anterior shoulder pathology, specifically subcoracoid impingement. Imaging of the coracohumeral distance during internal rotation with the hand at approximately midline should be considered to assess patients with anterior shoulder pain.

Shoulder impingement revisited: evolution of diagnostic understanding in orthopedic surgery and physical therapy

"Impingement syndrome" is a common diagnostic label for patients presenting with shoulder pain. Historically, it was believed to be due to compression of the rotator cuff tendons beneath the acromion. It has become evident that "impingement syndrome" is not likely an isolated condition that can be easily diagnosed with clinical tests or most successfully treated surgically. Rather, it is likely a complex of conditions involving a combination of intrinsic and extrinsic factors. A mechanical impingement phenomenon as an etiologic mechanism of rotator cuff disease may be distinct from the broad diagnostic label of "impingement syndrome". Acknowledging the concepts of mechanical impingement and movement-related impairments may better suit the diagnostic and interventional continuum as they support the existence of potentially modifiable impairments within the conservative treatment paradigm. Therefore, it is advocated that the clinical diagnosis of "impingement syndrome" be eliminated as it is no more informative than the diagnosis of "anterior shoulder pain". While both terms are ambiguous, the latter is less likely to presume an anatomical tissue pathology that may be difficult to isolate either with a clinical examination or with diagnostic imaging and may prevent potentially inappropriate surgical interventions. We further recommend investigation of mechanical impingement and movement patterns as potential mechanisms for the development of shoulder pain, but clearly distinguished from a clinical diagnostic label of "impingement syndrome". For shoulder researchers, we recommend investigations of homogenous patient groups with accurately defined specific pathologies, or with subgrouping or classification based on specific movement deviations. Diagnostic labels based on the movement system may allow more effective subgrouping of patients to guide treatment strategies.