The influence of variations of the coracoacromial arch on the development of rotator cuff tears

Study on Shoulder Joint Parameters and Available Supraspinatus Outlet Area Using Three-Dimensional Computed Tomography Reconstruction

Studies addressing the anatomical values of the supraspinatus outlet area (SOA) and the available supraspinatus outlet area (ASOA) are insufficient. This study focused on precisely measuring the SOA and ASOA values in a sample from the Chinese population using 3D CT (computed tomography) reconstruction. We analyzed CT imaging of 96 normal patients (59 males and 37 females) who underwent shoulder examinations in a hospital between 2011 and 2021. The SOA, ASOA, acromiohumeral distance (AHD), coracohumeral distance (CHD), coracoacromial arch radius (CAR), and humeral head radius (HHR) were estimated, and statistical correlation analyses were performed. There were significant sex differences observed in SOA (men: 957.62 ± 158.66 mm2; women: 735.87 ± 95.86 mm2) and ASOA (men: 661.35 ± 104.88 mm2; women: 511.49 ± 69.26 mm2), CHD (men: 11.22 ± 2.24 mm; women: 9.23 ± 1.35 mm), CAR (men: 37.18 ± 2.70 mm; women: 33.04 ± 3.15 mm), and HHR (men: 22.65 ± 1.44 mm; women: 20.53 ± 0.95 mm). Additionally, both SOA and ASOA showed positive and linear correlations with AHD, CHD, CAR, and HHR (R: 0.304-0.494, all p < 0.05). This study provides physiologic reference values of SOA and ASOA in the Chinese population, highlighting the sex differences and the correlations with shoulder anatomical parameters.

Rotator Cuff Repair With Acromioplasty Is Associated With an Increased Rate of Revision and Subsequent Procedures

Purpose

To evaluate the mid-term rate of revision arthroscopic rotator cuff repair as well as ipsilateral shoulder reoperations after index rotator cuff repair performed with or without acromioplasty in the United States.

Methods

The Medicare Standard Analytic File, which encompasses the entire Medicare billing and payment data, was queried between 2005 and 2014. Patients undergoing arthroscopic rotator cuff repair were identified and stratified based on whether ipsilateral acromioplasty was concurrently performed using Current Procedural Terminology codes. Groups were matched by age, sex, year of index procedure, and Elixhauser index at a 2:1 ratio. Primary end point was defined as undergoing a repeat ipsilateral shoulder surgery related to the rotator cuff at 5 years of follow-up. Kaplan-Meier survival curves were constructed, and the 2 groups were compared using the log-rank test.

Results

After matching, 54,209 shoulders in the rotator cuff repair with acromioplasty group and 26,448 shoulders in the rotator cuff repair without acromioplasty group were identified. Shoulders undergoing concurrent acromioplasty at index rotator cuff repair had a significantly increased rate of repeat ipsilateral cuff repair at 5 years postoperatively (8.5% vs 6.8%, P < .001). Similarly, there was an increased rate of reoperation of all types to the ipsilateral shoulder in cases where concurrent acromioplasty was performed (9.6% vs 9.1%, P < .001).

Conclusions

Using a large, national database, concurrent acromioplasty at the time of rotator cuff tear was found to be associated with both an increase rate of overall subsequent procedures and revision rotator cuff repair.

Level of Evidence

III, retrospective comparative study.

A novel method for determining the X-ray beam angulation of the supraspinatus outlet view

BACKGROUND

Rapid and accurate quantification of the supraspinatus outlet view (SOV) is a clinical challenge.

PURPOSE

To quantify the X-ray beam angle of the SOV using the horizontal angle of the subscapular spine line (SSSL) and to further verify the feasibility of this method.

MATERIAL AND METHODS

A total of 119 patients who underwent shoulder computed tomography (CT) examination were enrolled in the retrospective study. Three-dimensional (3D) CT reconstruction was performed and manually adjusted to provide the position similar to SOV. The rotation angle of the 3D image along the long axis of the human body (marked as β) was obtained. The horizontal angle of SSSL (marked as α) was measured on the anteroposterior localizer image of shoulder CT. Pearson correlation and linear regression correlation analysis were performed. In addition, the first-time success rate between the experience-based group and the measurement-based group were compared to verify the novel method.

RESULTS

We found a linear correlation between α and β (r = 0.962; P = 0.000). There was no significant correlation between the experience-based group and the measurement-based group in terms of age (P = 0.500), sex (P = 0.397), and side (P = 0.710), but there was a significant statistical difference in the first success rate between the two validation groups (χ² = 5.808^a, P = 0.016).

CONCLUSION

This novel quantitative measurement method for determining the X-ray beam angle of SOV using the horizontal angle of SSSL is feasible.

Biological connective tissues exhibit viscoelastic and poroelastic behavior at different frequency regimes: Application to tendon and skin biophysics

In this study, a poroviscoelastic finite element model (FEM) was developed and used in conjunction with an AFM-based wide-bandwidth nanorheology system to predict the frequency-dependent mechanical behavior of tendon and dermis subjected to compression via nanoindentation. The aim was to distinguish between loading rates that are dominated by either poroelasticity, viscoelasticity, or the superposition of these processes. Using spherical probe tips having different radii, the force and tip displacement were measured and the magnitude, E^∗, and phase angle, ϕ, of the dynamic complex modulus were evaluated for mouse supraspinatus tendon and mouse dermis. The peak frequencies of the phase angle were associated with the characteristic time constants of poroelastic and viscoelastic material behavior. The developed FE model could predict the separate poroelastic and viscoelastic responses of these soft tissues over a 4 decade frequency range, showing good agreement with experimental results. We observed that poroelasticity was the dominant energy dissipation mechanism for mouse dermis and supraspinatus tendon at higher indentation frequencies (10² to 10⁴ Hz) whereas viscoelasticity was typically dominant at lower frequencies (<10² Hz). These findings show the underlying mechanical behavior of biological connective tissues and give insight into the role played by these different energy dissipation mechanisms in governing the function of these tissues at nanoscale.

STATEMENT OF SIGNIFICANCE

Soft biological tissues exhibit complex, load- and time-dependent mechanical behavior. Evaluating their mechanical behavior requires sophisticated experimental tools and numerical models that can capture the fundamental mechanisms governing tissue function. Using an Atomic-force-microscopy-based rheology system and finite element models, the roles of the two most dominant time-dependent mechanisms (poroelasticity and viscoelasticity) that govern the dynamic loading behavior of mouse skin and tendon have been investigated. FE models were able to predict and quantify the contribution of each mechanism to the overall dynamic response and confirming the presence of these two distinct mechanisms in the mechanical response. Overall, these results provide novel insight into the viscoelastic and poroelastic properties of mouse skin and tendon and promote better understanding of the underlying origins of each mechanism.

Tear progression of symptomatic full-thickness and partial-thickness rotator cuff tears as measured by repeated MRI

PURPOSE

The purpose of this study was to analyse the natural course of symptomatic full-thickness and partial-thickness rotator cuff tears treated non-operatively and to identify risk factors affecting tear enlargement.

METHODS

One hundred and twenty-two patients who received non-surgical treatment for a partial- or full-thickness supraspinatus tear were included in this study. All rotator cuff tears were diagnosed with magnetic resonance imaging (MRI), and the same modality was used for follow-up studies. Follow-up MRI was performed after at least a 6-month interval. We evaluated the correlation between tear enlargement and follow-up duration. Eleven risk factors were analysed by both univariate and multivariate analyses to identify factors that affect enlargement of rotator cuff tears. The mean follow-up period was 24.4 ± 19.5 months.

RESULTS

Out of 122 patients, 34 (27.9%) patients had an initial full-thickness tear and 88 (72.1%) patients had a partial-thickness tear. Considering all patients together, tear size increased in 51/122 (41.8%) patients, was unchanged in 65/122 (53.3%) patients, and decreased in 6/122 (4.9%) patients. Tear size increased for 28/34 (82.4%) patients with full-thickness tears and 23/88 (26.1%) patients with partial-thickness tears. From the two groups which were followed over 12 months, a higher rate of enlargement was observed in full-thickness tears than in partial-thickness tears (6-12 months, n.s.; 12-24 months, P = 0.002; over 24 months, P < 0.001). Logistic regression revealed that having a full-thickness tear was the most reliable risk factor for tear progression (P < 0.001).

CONCLUSIONS

This study found that 28/34 (82.4%) of symptomatic full-thickness rotator cuff tears and 23/88 (26.1%) of symptomatic partial-thickness tears increased in size over a follow-up period of 6-100 months. Full-thickness tears showed a higher rate of enlargement than partial-thickness tears regardless of the follow-up duration. Univariate and multivariate analyses suggested that full-thickness tear was the most reliable risk factor for tear enlargement. The clinical relevance of these observations is that full-thickness rotator cuff tears treated conservatively should be monitored more carefully for progression than partial-thickness tears.

LEVEL OF EVIDENCE

IV.

The Coracoacromial Ligament: Anatomy, Function, and Clinical Significance

The coracoacromial ligament (CAL) was first described as a pain generator by Dr Charles Neer in the early 1970s. Since that time, considerable controversy regarding CAL management during acromioplasty has persisted. This review aims to better understand the role of the CAL in shoulder physiology and pathology. Sixty-six articles from 1958 to 2016 were identified using an electronic search of PubMed, Cochrane Library, AccessMedicine, and MD Consult for case series as well as cohort and prospective studies. The authors used “coracoacromial ligament” and “coracoacromial veil” as medical subject headings (MeSH). In addition, reference lists from all identified articles were reviewed for studies that the search terms may have omitted. The CAL plays an important role in shoulder biomechanics, joint stability, and proprioception. Morphological variance of the CAL is evident throughout the literature. Age-dependent changes due to chronic stress and cellular degradation cause thickening and stiffening of the CAL that may contribute to a spectrum of shoulder pathology from capsular tightness to rotator cuff tear arthropathy and impingement syndrome. The CAL is an integral component of the coracoacromial arch. CAL release during acromioplasty remains controversial. Future clinical outcomes research should endeavor to advance the understanding of the CAL to refine clinical and intraoperative decision making regarding its management.

Tendon exhibits complex poroelastic behavior at the nanoscale as revealed by high-frequency AFM-based rheology

Tendons transmit load from muscle to bone by utilizing their unique static and viscoelastic tensile properties. These properties are highly dependent on the composition and structure of the tissue matrix, including the collagen I hierarchy, proteoglycans, and water. While the role of matrix constituents in the tensile response has been studied, their role in compression, particularly in matrix pressurization via regulation of fluid flow, is not well understood. Injured or diseased tendons and tendon regions that naturally experience compression are known to have alterations in glycosaminoglycan content, which could modulate fluid flow and ultimately mechanical function. While recent theoretical studies have predicted tendon mechanics using poroelastic theory, no experimental data have directly demonstrated such behavior. In this study, we use high-bandwidth AFM-based rheology to determine the dynamic response of tendons to compressive loading at the nanoscale and to determine the presence of poroelastic behavior. Tendons are found to have significant characteristic dynamic relaxation behavior occurring at both low and high frequencies. Classic poroelastic behavior is observed, although we hypothesize that the full dynamic response is caused by a combination of flow-dependent poroelasticity as well as flow-independent viscoelasticity. Tendons also demonstrate regional dependence in their dynamic response, particularly near the junction of tendon and bone, suggesting that the structural and compositional heterogeneity in tendon may be responsible for regional poroelastic behavior. Overall, these experiments provide the foundation for understanding fluid-flow-dependent poroelastic mechanics of tendon, and the methodology is valuable for assessing changes in tendon matrix compressive behavior at the nanoscale.

Decreased axial coracoid inclination angle is associated with rotator cuff tears

PURPOSE

Coracoid morphology has been related to coracoid impingement mainly resulting in anterior shoulder pain aggravated by forward flexion and internal rotation. However, the coracoid process morphology can also affect the inclination of the coracoacromial ligament and subsequently the subacromial space in the same way that acromial slope does. The purpose of this study was to evaluate the influence of the coracoid body-glenoid surface, coracoid tip-glenoid surface, and coracoid body-coracoid tip angles (coracoid inclination angles) on rotator cuff tears (RCTs).

METHODS

Fifty patients with documented RCT and 50 patients with normal rotator cuff (control) were included. The coracoid inclination angles were determined in both groups by measuring on computed tomography scans the angle created by the coracoid body and the glenoid surface (A1), the angle created by the coracoid tip and the glenoid surface (A2), and the angle created by the coracoid body and the coracoid tip (A3).

RESULTS

All angles were significantly lower in the RCT group compared to the control group: mean A1 angle of 49.7° and 54.61°, respectively ( p = 0.011); mean A2 angle of 76.45° and 93.6°, respectively ( p < 0.001); and mean A3 angle of 132.33° and 144.34°, respectively ( p < 0.001).

CONCLUSIONS

Decreased coracoid body-glenoid surface, coracoid tip-glenoid surface, and coracoid body-coracoid tip angles are associated with RCT. Decreased angles may reduce subacromial space by projecting the coracoacromial ligament more vertically.

Anatomical and morphological study of the subcoracoacromial canal

INTRODUCTION

Many clinical anatomy studies have looked into how variations in the acromion, coracoacromial ligament (CAL) and subacromial space are associated with rotator cuff injuries. However, no study up to now had defined anatomically the fibro-osseous canal that confines the supraspinatus muscle in the subcoracoacromial space. Through an anatomical study of the scapula, we defined the bone-related parameters of this canal and its anatomical variations.

MATERIALS AND METHODS

This study on dry bones involved 71 scapulas. With standardised photographs in two orthogonal views (superior and lateral), the surface area of the subcoracoacromial canal and the anatomical parameters making up this canal were defined and measured using image analysis software. The primary analysis evaluated the anatomical parameters of the canal as a function of three canal surface area groups; the secondary analysis looked into how variations in the canal surface area were related to the type of acromion according to the Bigliani classification.

RESULTS

Relative to glenoid width, the group with a large canal surface area (L) had significantly less lateral overhang of the acromion than the group with a small canal surface area (S), with ratios of 0.41±0.23 and 0.58±0.3, respectively (P=0.04). The mean length of the CAL was 46±8mm in the L group and 39±9mm in the S group (P=0.003). The coracoacromial arch angle was 38°±11° in the L group and 34°±9° in the S group; the canal surface area was smaller in specimens with a smaller coracoacromial arch angle (P=0.20).

CONCLUSION

Apart from acromial morphology, there could be innate anatomical features of the scapula that predispose people to extrinsic lesions to the supraspinatus tendon (lateral overhang, coracoacromial arch angle) by reducing the subcoracoacromial canal's surface area.

LEVEL OF EVIDENCE

Anatomical descriptive study.

Rotator cuff tear: A detailed update

Rotator cuff tear has been a known entity for orthopaedic surgeons for more than two hundred years. Although the exact pathogenesis is controversial, a combination of intrinsic factors proposed by Codman and extrinsic factors theorized by Neer is likely responsible for most rotator cuff tears. Magnetic resonance imaging remains the gold standard for the diagnosis of rotator cuff tears, but the emergence of ultrasound has revolutionized the diagnostic capability. Even though mini-open rotator cuff repair is still commonly performed, and results are comparable to arthroscopic repair, all-arthroscopic repair of rotator cuff tear is now fast becoming a standard care for rotator cuff repair. Appropriate knowledge of pathology and healing pattern of cuff, strong and biological repair techniques, better suture anchors, and gradual rehabilitation of postcuff repair have led to good to excellent outcome after repair. As the healing of degenerative cuff tear remains unpredictable, the role of biological agents such as platelet-rich plasma and stem cells for postcuff repair augmentation is still under evaluation. The role of scaffolds in massive cuff tear is also being probed.

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.

Acromial morphology in patients with calcific tendinitis of the shoulder

PURPOSE

The purpose of this study was to evaluate whether the morphology of the acromion in calcific tendinitis differs from controls without subacromial pathology and matches subacromial impingement.

METHODS

Digital radiographs of 150 shoulders were evaluated with the open source DICOM-Viewer OsiriX. 50 patients had symptomatic calcific tendinitis of the shoulder, 50 had subacromial impingement without calcifications or rotator cuff tears, 50 with bruised shoulder that were previously asymptomatic served as controls. Acromial shape according to Bigliani et al. acromial tilt (AT) according to Kitay et al. and Aoki et al. acromion index (AI) according to Nyffeler et al. and lateral acromial angle (LAA) according to Banas et al. were measured.

RESULTS

Both calcific (0.72; P = 0.001) and impingement groups (0.73; P = 0.008) were significantly different from controls (0.67) using AI measure, while only the calcific group (79.5°) was different from controls (84.1°) using LAA (P < 0.001), and only the impingement group (32.9°) was different from controls (29.2°) using AT (P < 0.001). An LAA <70° only occurred in two patients with calcific tendinitis.

CONCLUSION

The hypothesis of this study was that the morphology of the acromion in calcific tendinitis differs from controls without subacromial pathology and matches subacromial impingement was only confirmed for the AI. The AI of shoulders with calcific tendinitis is comparable to that of shoulders with subacromial impingement.

Human evolution and tears of the rotator cuff

PURPOSE

Humans differ from other great ape species in their propensity to develop tears of the rotator cuff. The aim of this study was to compare the anatomical risk factors for subacromial impingement and rotator cuff tears amongst the great apes and to determine which features may be accentuated in humans and therefore play a more significant role in disease aetiology.

METHODS

Orthogonal digital photographs of 22 human, 17 gorilla, 13 chimpanzee and 12 orangutan dry bone scapula specimens oriented in the glenoid plane were taken. Anatomical measurements were preformed using a calibrated digital image technique and the results scaled according to scapula vertebral border length.

RESULTS

Of the ten anatomical features associated with subacromial impingement and rotator cuff tears in humans, none were shown to be accentuated and significantly different to the other species studied. However the human supraspinatus fossa was shown to be significantly smaller.

CONCLUSIONS

These results indicate that an alternative primary aetiological factor for rotator cuff tears must exist. A reduction in the size of the supraspinatus fossa in human scapulae suggests that structural insufficiency of the supraspinatus or a change in rotator cuff force vectors could play a role.

Diagnostic imaging guideline for musculoskeletal complaints in adults-an evidence-based approach-part 2: upper extremity disorders

PURPOSE

To develop evidence-based diagnostic imaging practice guidelines to assist chiropractors and other primary care providers in decision making for the appropriate use of diagnostic imaging for upper extremity disorders.

METHODS

A comprehensive search of the English and French language literature was conducted using a combination of subject headings and keywords. The quality of the citations was assessed using the Quality of diagnostic accuracy studies (QUADAS), the Appraisal of Guidelines Research and Evaluation (AGREE), and the Stroke Prevention and Educational Awareness Diffusion (SPREAD) evaluation tools. The Referral Guidelines for Imaging (radiation protection 118) coordinated by the European Commission served as the initial template. The first draft was sent for an external review. A Delphi panel composed of international experts on the topic of musculoskeletal disorders in chiropractic radiology, clinical sciences, and research was invited to review and propose recommendations on the indications for diagnostic imaging. The guidelines were pilot tested and peer-reviewed by practicing chiropractors and by chiropractic and medical specialists. Recommendations were graded according to the strength of the evidence. Dissemination and implementation strategies are discussed.

RESULTS

Recommendations for diagnostic imaging guidelines of adult upper extremity disorders are provided, supported by over 126 primary and secondary citations. The overall quality of available literature is low, however. On average, 44 Delphi panelists completed 1 of 2 rounds, reaching over 88% agreement on all 32 recommendations. Peer review by specialists reflected high levels of agreement and perceived ease of use of guidelines and implementation feasibility.

CONCLUSIONS

The guidelines are intended to be used in conjunction with sound clinical judgment and experience and should be updated regularly. Future research is needed to validate their content.

The relationship of glenoid and humeral version with supraspinatus tendon tears

The aim of this study was to investigate the relationship of glenohumeral anatomic measurements on MR imaging with supraspinatus tendon tears. The study was approved by the institutional review board and informed consent was obtained from each subject. Forty-two patients (mean age 55.5 years; age range 40-73 years) with supraspinatus tendon tears and 50 asymptomatic shoulders of 32 controls (mean age 43 years; age range 17-69 years) without rotator cuff tears were included. The acromio-glenoid and supraspinatus-glenoid angles were measured on coronal images, the glenoid and humeral head version as well as the bicipital-humeral distance on axial images. Significant differences were found between the patients and controls for both glenoid version and bicipital-humeral distance, which are considered to influence the distribution of forces placed on the cuff (p < 0.05). The patients had a decreased glenoid version by an average of 2.3 degrees (-7.1 +/- 7.8 degrees vs. -4.8 +/- 5.6 degrees), and a decreased bicipital-humeral distance by an average of 2.7 mm (12.1 +/- 3.7 mm vs. 14.8 +/- 4.1 mm). No significant differences were found between these groups for humeral head version and the acromio-glenoid and supraspinatus-glenoid angles, which might contribute to extrinsic impingement by narrowing the supraspinatus tendon outlet. Differences in glenoid and humeral version may be responsible for RC tears by changing the orientation of the rotator cuff and thus increasing shearing stress.

Acromial morphology: effects of suboptimal radiographs

Acromial morphology is one of the important factors related to rotator cuff pathology, especially if there is acromial encroachment onto the supraspinatus tendon. This is the rationale for many surgeons performing an acromioplasty, based on preoperative radiographs, in their treatment of rotator cuff disease. However, geometric measurements of the acromion are dependent on the radiographic view, and suboptimal radiographs of the scapula might bias the acromial morphology on the radiographs. Our objective was to study the effect of suboptimal lateral-view radiographs of the scapula on 6 acromial angles, which have been correlated with rotator cuff pathology, by use of a computational method. Anatomic landmarks were digitized on 12 cadaveric scapulae via a spatial linkage system. A coordinate system based on the scapula was then created that allowed projection of the anatomic landmarks on the sagittal plane and simulated the optimal lateral-view radiograph of the scapula. By rotating the coordinate system in the coronal plane (cranial and caudal projections) and axial plane (anterior and posterior projections) with 5 degrees, 10 degrees, 15 degrees, and 20 degrees increments, 16 suboptimal lateral-view radiographs of the scapula were simulated. Significant differences in the 6 acromial angles (P < .01) between the optimal and suboptimal lateral-view radiographs of the scapula were found in almost every cranial and caudal projection. Rotating the projection in the axial plane did not significantly affect the acromial angles (P > .05) up to 20 degrees of rotation in the anterior and posterior direction. Of the 6 different acromial angles, the acromial slope was least affected when the projection was varied. In contrast, the anterior slope of the acromion was highly affected by errors in the projection.

The influence of the acromial coverage index in rotator cuff tears

Several intrinsic and extrinsic factors have been advocated in the pathogenesis of rotator cuff tears, but it is still unclear whether the origin of the tear is related to tendon degeneration itself or induced by several morphologic changes. The purpose of this study is to determine the relationship between the acromial coverage of the humeral head and the presence of a cuff tear. We evaluated 148 shoulders, including 45 that underwent surgical rotator cuff repair (group I), 26 with documented rotator cuff tears treated conservatively (group II), and 77 with no cuff pathology as a control group (group III). The mean acromial coverage index was 0.68 in group I, 0.72 in group II, and 0.59 in group III, giving a highly significant difference (P < .0001) between the control group and both cuff tear groups. Patients with a cuff tear have a significantly higher acromial coverage index than the control group.

Acromial spur: relationship to aging and morphologic changes in the rotator cuff

This study's objective is to elucidate the relationship between acromial spur formation and rotator cuff pathology or aging. The subjects comprised 1029 shoulders in control, cadaveric, and operative groups. A radiograph in the supraspinatus outlet view was taken in all subjects. The lengths of the incident spurs were measured and classified into 3 sizes (small, <5 mm; medium, <10 mm; and large, > or =10 mm). The rotator cuff was macroscopically classified as normal or as having bursal-side fraying, joint-side tear, intratendinous tear, bursal-side tear, complete tear limited to the supraspinatus tendon, or massive tear. In the control group, the overall incidence of spurs and spur size increased with advancing age (P < .001), but the majority of spurs were small (<5 mm). In the cadaveric group, the overall incidence did not correlate with advancing age (P > .05). However, spur size increased with age in subjects aged 50 years or older (P < .001). The incidence of spurs in rotator cuffs with bursal-side tears was highest and was significantly higher than that in normal cuffs and cuffs with bursal-side fraying and intratendinous tears. We observed 40% of medium spurs and 69% of large spurs in cases with bursal-side tears, complete tears limited to the supraspinatus tendon, and massive tears. In the operative group, the overall incidence correlated to advancing age (P < .001), reaching 80% or more in subjects aged 30 years or older. In addition, the size of spurs was larger than that in the other 2 groups in all age groups with few exceptions (P < .05). Small spurs were associated with advancing age. Morphologic change to the bursal side of the rotator cuff may enhance spur growth. The presence of a small spur has no diagnostic value for rotator cuff tears. Spurs measuring 5 mm or more, however, are of diagnostic value because of their high rate of association with bursal-side tear, complete tears limited to the supraspinatus tendon, or massive tears.

The coracoacromial ligament: morphology and study of acromial enthesopathy

The coracoacromial ligament (CAL), normally a superior restraint against humeral translation, is frequently involved in rotator cuff impingement pathology. However, surgical excision of the CAL is not always clinically successful. Little anatomic information exists about the morphology and function of this ligament. The CAL and glenohumeral joint in 56 cadaveric shoulders were examined in 31 cadavers. Nineteen dimensional parameters were obtained by direct measurement. In 16 shoulders, specific attention was directed at the anterior band of the CAL. Variation exists in the morphology of the CAL. The most common configuration of the CAL was two distinct ligamentous bands that could be classified anatomically as an anterolateral band (ALB) and posteromedial band (PMB). The ALB commonly extended to the posterolateral aspect of the acromion. Furthermore, it frequently extended anterolaterally to the acromion, ending in a coracoacromial falx. Spur formation had occurred in 10 of 16 shoulders evaluated and always appeared in the ALB. Spur formation in the ALB correlated with a focal CAL that was narrower, less divergent, shorter, and thicker than a diffuse CAL that did not have a spur. The mean angle of diversion between the ALB and PMB, when a spur was present, was 31 degrees compared with 45 degrees when no spur was present. CAL band thickness varied, with the ALB being thicker at the acromion than at the coracoid and the PMB being thicker at the coracoid than at the acromion. During arthroscopic subacromial decompression, failure to visualize the anterolateral corner of the acromion adequately may result in incomplete resection of the CAL, especially if the PMB is mistaken to be the entire ligament. Incomplete removal of the CAL may be a factor in clinical failures of arthroscopic subacromial decompression. The preferential location of spurs in the ALB suggests that it is a major load-bearing structure. Furthermore, the ALB is thicker at the acromion, suggesting increased strain. Our data suggest that a possible function of the CAL is to dampen stress on the acromion from muscle activity.

Glenoid version and rotator cuff tears

The purpose of this study was to determine the relationship between rotator cuff (RC) tear and the orientation of the glenoid. Ninety-six shoulders (94 patients) that underwent open RC repair were grouped according to the type of tear. We measured on MRI the acromio-glenoid angle (AG) and the supraspinatus fossa glenoid angle on the anterior-posterior (SGAP) and axial (SGAX) views. RC patients had a smaller AG angle (76+/-7 degrees vs. 86+/-10 degrees ) and a larger SGAP angle (112+/-6 degrees vs. 102+/-7 degrees ) compared to controls (p<0.001). We also found a highly significant difference (p<0.001) in glenoid version measured by SGAX between anterior cuff tears (-5+/-4 degrees ) and posterior cuff tears (3+/-3 degrees ). Furthermore, we identified an association between RC tear and the orientation of the glenoid relative to the axis of the supraspinatus fossa. Greater retroversion is predictive of an anterior cuff injury and greater anteversion is predictive of a posterior cuff injury.

Acromial shapes and extension of rotator cuff tears: magnetic resonance imaging evaluation

Magnetic resonance imaging makes it possible to inspect the status of the rotator cuff and the shape of the acromion. To clarify the relationship between acromial shapes and rotator cuff tears, we evaluated magnetic resonance images obtained in 192 shoulders. We classified the acromial shapes into 3 types: type I (flat), type II (curved), and type III (hooked). Among a group of 91 shoulders with rotator cuff tears, 33 (36.3%) were type I, 22 (24.2%) type II, and 36 (39.6%) type III. The size of rotator cuff tears in type III acromions was significantly larger than in type I or II acromions. Comparison of the incidence of each acromial shape between groups of specimens with and without rotator cuff tears revealed no significant differences. We suggest that whereas acromial shapes have a bearing on the extent of rotator cuff tears, the correlation between rotator cuff tears and a type III acromion is not as strong as has been suggested in the literature.

Anatomic variations of the coracoacromial ligament in neonatal cadavers: a neonatal cadaver study

One of the most common causes of pain and disability in the upper limb is inflammation of the rotator cuff tendons. When no significant bony abnormality exists in the surrounding structures, the coracoacromial ligament has been implicated as a possible cause of impingement on the cuff tendons and various morphological variants of the ligament have so far been claimed to be either the cause or the result of impingement. In this study, 110 shoulders from 60 neonatal cadavers that were preserved in a preparation of formaldehyde were dissected. Anatomic variations of coracoacromial ligaments were investigated with metric and histologic analysis. Three main ligament types were identified: quadrangular, broad band and U-shaped. The multiple banded ligament was not found. Histologic analysis showed that in U-shaped ligaments a thin tissue existed in the central part of the ligament close to the coracoid. Comparing our data with the adult measurements of a previous study we suggest that the primordial ligament is broad shaped, but assumes a quadrangular shape due to the different growth rates of the coracoid and acromial ends. We also suggest that broad and U-shaped ligaments account for the primordial and quadrangular and Y-shaped ligaments account for the adult types of the single or double banded anatomic variants respectively. Our results show that various types of the coracoacromial ligament are present at the neonatal period and that the final shape of the ligament should be defined by developmental factors, rather than degenerative changes.

Supraspinatus outlet view in the diagnosis of stages II and III impingement syndrome

PURPOSE

To compare supraspinatus outlet view (SOV) findings at different stages of the impingement syndrome (IS) with findings in asymptomatic age- and sex-matched controls.

MATERIAL AND METHODS

Pre-operative SOVs were obtained of 37 shoulders of patients scheduled for unilateral open repair of a full-thickness rotator cuff tear (stage III IS) and 74 shoulders of patients scheduled for open (n=46) or arthroscopic (n=28) acromioplasty for tendinitis (stage II IS). Each view of a patient's shoulder was paired with a control view obtained from an age- and sex-matched person with no shoulder problems (n=111).

RESULTS

There were no significant differences in acromial morphology as evaluated on the scale devised by BIGLIANI et al. or in the tilt, slope or length of the acromion between the study groups and their controls. However, hooked acromion seemed to be more common in the patients. The thickness of the anterior part of the acromion at the tendinitis stage and the acromial angle at the tear stage of IS were the only parameters that showed significant differences between patients and controls.

CONCLUSION

Variation of the morphology of the acromion as evaluated on a basis of the SOV is associated with IS, but the association is weak and its value in the diagnosis of IS is therefore only as an adjunctive to other diagnostic modalities.

Diagnosis and treatment of anterosuperior rotator cuff tears

Nineteen of 407 patients who underwent rotator cuff repair surgery over a 6-year period were found to have a tear of the subscapularis in combination with the supraspinatus and infraspinatus tendons. Nine of these patients had an unsuccessful prior surgery, which failed to recognize the extent of the subscapularis component. Surgical repair of the subscapularis tendon required a deltopectoral approach, and repair of the supraspinatus and infraspinatus components of the tear could only be accomplished through this approach in 4 patients. In the remaining 15, an extended superior approach was required to mobilize and repair the supraspinatus and infraspinatus tendons. In all cases, the biceps tendon was either torn or severely degenerated, requiring tenodesis. At a mean follow-up of 40 months (range 24 to 75 months), subjective results were excellent in 5 patients, good in 3, fair in 4, and poor in 7. The modified Constant score improved to a mean of 69% (range 23% to 130%), compared with a preoperative mean of 38% (range 23% to 100%). Physical findings positive for subscapularis insufficiency persisted in 14 of 19 patients. A significant correlation (P <.05) was found between a lower Constant score and duration of symptoms longer than 6 months as well as an appearance of severe fatty degeneration and atrophy of the subscapularis muscle on magnetic resonance imaging. We conclude that anterosuperior rotator cuff tears are an infrequent configuration that may require surgical repair through an extended approach combining deltopectoral mobilization of the subscapularis with transdeltoid mobilization of the supraspinatus and infraspinatus. Repair before 6 months of symptoms is associated with a better functional outcome and is the result of less involution of muscle and tendon tissue.

Anatomic and functional aspects of the kinetics of the shoulder joint capsule and the subacromial bursa

This anatomic study was devoted to the kinetics of the shoulder joint and especially the subacromial region. Following dissection of the shoulder joint capsule and subacromial region of 80 unpreserved shoulder joints, the anatomic relationships of the subacromial space in the neutral position and in continuous abduction (30 degrees, 60 degrees and 90 degrees with fixed scapulae) were examined. These investigations were supplemented by histologic preparations. In the course of our examinations we discovered a gliding mechanism of the subacromial bursa. Moreover, we found a subcoracoid attachment of the shoulder joint capsule and a precoracoid ligamentous connection running between the short head of the biceps brachii m. and the coracoacromial ligament. We termed this the coracoid aponeurosis, which facilitates gliding behaviour of the shoulder joint capsule beneath the coracoid process. In view of this gliding mechanism of the subacromial bursa and the coracoid aponeurosis, discovered in the course of our investigations, we have to reassess the kinetics of the sub-acromial and subcoracoid space. Further, we should reconsider our operative technique in cases of the subacromial or subcoracoid impingement syndrome.