Radiographic joint space in normal acromioclavicular joints

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.

Management of Acromioclavicular Joint Injuries: A Historic Account

There has been a rapid evolution in best practice management of acromioclavicular (AC) joint injuries. AP, Zanca, scapular Y, and dynamic axillary radiographic views provide optimal visualization of the joint and may assess for the presence of horizontal AC instability. Severity of AC joint pathology is classified according to the 6-tier Rockwood scoring system. Over 160 surgical techniques have been described for AC joint repair and reconstruction in the last decade; as a result, determining the optimal treatment algorithm has become increasingly challenging secondary to the lack of consistently excellent clinical outcomes.

Physeal injuries of the clavicle: pediatric counterparts to adult acromioclavicular and sternoclavicular joint separations

The epiphyses at the medial and lateral ends of the clavicle are small, ossify relatively late, and may not fuse until early adulthood. Because of this unique anatomy, pediatric and young adult injuries that involve the clavicle often differ from the patterns typically seen in older adults. Clavicular trauma that affects the acromioclavicular joint laterally or sternoclavicular joint medially often results in a physeal fracture and as such, can go unrecognized or be mistaken for a joint dislocation. Radiographic assessment is challenging, particularly when the epiphysis is not yet ossified. However, MR imaging allows for visualization of the cartilage, periosteum and perichondrium, and ligaments of the affected joints. Lateral clavicle physeal injuries can be categorized by the Dameron and Rockwood system, the pediatric correlate to the Rockwood classification of adult acromioclavicular joint injuries. Medial clavicle physeal fractures, similar to adult sternoclavicular joint dislocations, may result in anterior or posterior displacement. Because of their great ability to heal and remodel, clavicular physeal fractures respond better to conservative management than true acromioclavicular or sternoclavicular joint dislocations. Therefore, it is essential to recognize the true nature of these injuries, as there are implications for successful treatment and appropriate prognosis.

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.

Acromioclavicular Joint Injury and Repair

The acromioclavicular (AC) joint is commonly injured in athletes participating in contact and overhead throwing sports. Injuries range from simple sprains to complete ligamentous disruption, and they are classified by the established Rockwood grading system. High-grade injuries are associated with fractures around the AC joint and disruption of the superior shoulder suspensory complex, a ring of osseous and ligamentous structures at the superior aspect of the shoulder. Radiographs are the mainstay of imaging of the AC joint, with magnetic resonance imaging reserved for high-grade injuries to aid classification and plan surgical management. Low-grade AC joint injuries tend to be managed conservatively, but a wide range of surgical procedures have been described for higher grade injuries and fractures around the AC joint. This review illustrates the anatomy of the AC joint and surrounding structures, the imaging features of AC joint injury, and the most commonly performed methods of reconstruction and their complications.

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.

Imaging of the Acromioclavicular Joint: Anatomy, Function, Pathologic Features, and Treatment

The acromioclavicular joint is an important component of the shoulder girdle; it links the axial skeleton with the upper limb. This joint, a planar diarthrodial articulation between the clavicle and the acromion, contains a meniscus-like fibrous disk that is prone to degeneration. The acromioclavicular capsule and ligaments stabilize the joint in the horizontal direction, while the coracoclavicular ligament complex provides vertical stability. Dynamic stability is afforded by the deltoid and trapezius muscles during clavicular and scapular motion. The acromioclavicular joint is susceptible to a broad spectrum of pathologic entities, traumatic and degenerative disorders being the most common. Acromioclavicular joint injury typically affects young adult males and can be categorized by using the Rockwood classification system as one of six types on the basis of the direction and degree of osseous displacement seen on conventional radiographs. MRI enables the radiologist to more accurately assess the regional soft-tissue structures in the setting of high-grade acromioclavicular separation, helping to guide the surgeon's selection of the appropriate management. Involvement of the acromioclavicular joint and its stabilizing ligaments is also important for understanding and classifying distal clavicle fractures. Other pathologic processes encountered at this joint include degenerative disorders; overuse syndromes; and, less commonly, inflammatory arthritides, infection, metabolic disorders, and developmental malformations. Treatment options for acromioclavicular dysfunction include conservative measures, resection arthroplasty for recalcitrant symptoms, and surgical reconstruction techniques for stabilization after major trauma.

Acromioclavicular Joint: What to Look for

Acromioclavicular joint (ACJ) pathology is a common source of shoulder girdle pain, frequently coexisting with and sharing overlapping clinical features of rotator cuff and glenohumeral articular lesions. ACJ trauma and osteoarthritis dominate clinical presentation; however, an array of pathologies can affect the joint. MR imaging of the ACJ is a powerful secondary diagnostic tool in early diagnosis of ACJ pathology and in accurate assessment of ACJ injuries, helping to resolve clinically challenging cases and allowing for individualized treatment planning. Knowledge of ACJ anatomy, biomechanics, and pathology is fundamental to interpreting and providing a clinically relevant ACJ MR imaging report.

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.

Correlation of Macroscopic Osteoarthrotic Changes and Radiographic Findings in the Acromioclavicular Joint

In a total of 108 acromioclavicular articulations from cadavers the osteoarthrotic changes were studied. The articulations were macroscopically and radiographically ranked according to their grade of osteoarthrosis. The two ranking lines were correlated statistically and showed a rank correlation of 0.741. In 38 articulations tomography was also carried out. These articulations were classified into five grades of osteoarthrosis and the macroscopic, conventional radiographic and tomographic gradings were compared. The correlation coefficient for tomography versus macroscopy was 0.714. Tomography versus standard radiography showed a correlation of 0.767 and standard radiography versus macroscopy a correlation of 0.841. The standard radiographic investigation reveals moderate and severe osteoarthrotic changes in the acromioclavicular joint but cannot depict smaller changes. Tomography does not seem to improve the specificity. There is a need for a better radiologic technique in the examination of the acromioclavicular joint. Radiography during some kind of loading might be a practical way of improving the specificity and make it possible to show early osteoarthrosis in the acromioclavicular articulation.

Ultrasound guided joint space distance changes during manual traction of acromioclavicular joint in young and healthy adults

Introduction: Manual traction is a commonly used technique in manual therapy. However, depicting changes in joint space distance via real time imaging during traction is seldomly applied. The aims of the study were to identify ACJ joint space distance changes during manual traction and creation of a classification of the techniques upon the largest change in the resultant parameter (l) representing joint space distance.

Material and methods: Thirteen healthy volunteers were examined unilaterally. Acromioclavicular joint space distance changes were measured with dynamic ultrasound imaging during followingmanual traction techniques: International Academy of Orthopedic Medicine technique (IAOM AC), Karel Lewit’s Prague School of Manual Medicine & Rehabilitation technique (LAC) and author’s own proposition (B AC). The differences in joint space distance between resting position (RP) and the traction technique position, created three parameters of displacement - horizontal (x), vertical (y) and (l) - the resultant component.

Results: Parameters were not coherent with normal distribution. Statistical differences showed significance in the (x) parameter for IAOM AC compared with L AC (p<0,0183) and B AC (p<0,02). All techniques presented a significant increase of the resultant distance (l), compared with RP as the reference value - IAOM AC p<0,0036, L AC and B AC p<0,0000. In few cases L AC decreased the distance in the (x) parameter, but not significantly.

Conclusions:

1.Significant changes of (x) parameter did not correspond with the significance of the resultant parameter (l), which prevented authors from creating a classification of the techniques.

2.All traction techniques used in the study increased the joint space distance compared to RP, which confirms traction’s theoretical assumptions.

3.For clinical purpose the change of (x) parameter may prove crucial for therapy’s effectiveness, despite lack of change in the joint space distance in the resultant parameter (l) by itself.

Arthroscopic distal clavicle resection in symptomatic acromioclavicular joint arthritis combined with rotator cuff tear: a prospective randomized trial

BACKGROUND

The treatment of symptomatic acromioclavicular joint (ACJ) injury in the rotator cuff (RC) tear has not been well clarified.

PURPOSE

To compare the clinical results between patients who had distal clavicle resection (DCR) and those who did not during RC repair.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

From August 2008 to December 2009, a total of 56 consecutive patients (58 shoulders) were included. All patients had either a full-thickness or high-grade (>50%) RC tear, ACJ tenderness, arthritic change visible on plain radiographs, and a positive ACJ lidocaine injection test the day before surgery. Patients were randomized into 2 groups: DCR and RC repair (DCR+RCR group) and RC repair only (isolated RCR). Evaluation was performed preoperatively, at 6 months postoperatively, and at a final follow-up a minimum of 24 months postoperatively using the American Shoulder and Elbow Surgeons (ASES) score, the Constant shoulder score, range of motion examination, and pain visual analog scale (VAS).

RESULTS

After simple randomization, 26 shoulders were allocated in the DCR+RCR group, and 32 were placed in the isolated RCR group. Five shoulders in the DCR+RCR group and 6 in the isolated RCR group were excluded from analysis due to loss of follow-up. Therefore, the evaluation was performed for 21 shoulders in the DCR+RCR group and 26 shoulders in the isolated RCR group. The mean follow-up period was 44.2 months in the DCR+RCR group and 44.0 months in the isolated RCR group. There were no differences in age, sex, symptom duration, RC tear size, or preoperative ASES, Constant, and VAS scores between the 2 groups (P > .05). At final follow-up, the ASES, Constant, and VAS scores were significantly improved in both groups (P < .001). There were no differences in ASES, Constant, and VAS scores between the 2 groups at final follow-up (P > .05), and there was no difference in residual ACJ tenderness (7 in the DCR+RCR group and 5 in the isolated RCR group) between the 2 groups (P = .270).

CONCLUSION

There was no difference in the clinical evaluations between the combined arthroscopic DCR and RCR group and the isolated RCR group at a minimum 24-month follow-up. Arthroscopic DCR should be carefully considered in patients who have symptomatic ACJ arthritis with RC tears.

What role do plain radiographs have in assessing the skeletally immature acromioclavicular joint?

BACKGROUND

Because of incomplete ossification of the coracoid process and acromion, acromioclavicular joint configuration in the skeletally immature patient differs from that of adults. Although comparison to radiographic standards for this joint is critical in the evaluation of acromioclavicular joint injuries, these standards are not well defined for children or adolescents.

QUESTIONS/PURPOSES

We therefore sought to determine (1) the reliability of numerous radiographic measurements of the skeletally immature acromioclavicular joint, including the vertical and shortest coracoclavicular interval, and the acromioclavicular joint offset; (2) the timing of ossification of the acromion and coracoid in males and females; and (3) the differences in the values of these radiographic measurements based on age and sex.

METHODS

This study was based on a total of 485 subjects, 8 to 18 years old, who underwent conventional AP view radiographs of both shoulders. The 485 subjects were included to assess normal configuration around the acromioclavicular joint and 466 of these subjects were evaluated for comparison between both sides. The vertical and shortest coracoclavicular interval, coracoclavicular clavicle width ratio, acromioclavicular joint offset, and difference of the coracoclavicular interval of both sides were measured. A reliability test was conducted before obtaining the main measurements. The relationship of measurements with sex, age, and stage of ossification was evaluated.

RESULTS

The vertical and shortest coracoclavicular interval showed excellent reliability (intraclass correlation coefficient ([ICC], 0.918 and 0.934). The acromioclavicular joint offset showed low reliability (ICC, 0.543). The ossification centers of the acromion and the coracoid processes appeared and fused earlier in females than in males. The vertical coracoclavicular interval, which was not affected by partial ossification of the coracoid process, was less than 11 mm in the 90% quantile of total subjects in males and 10 mm in the 90% quantile in females. The difference of the vertical coracoclavicular interval of both sides was less than 50% in 436 of 466 (93.4%) patients.

CONCLUSIONS

The vertical coracoclavicular interval was the best parameter to assess acromioclavicular joint dislocation in skeletally immature patients. Comparison of both sides of the acromioclavicular joint could help to inform physicians in predicting the need for additional evaluations.

Mechanisms of rotator cuff tendinopathy: intrinsic, extrinsic, or both?

The etiology of rotator cuff tendinopathy is multi-factorial, and has been attributed to both extrinsic and intrinsic mechanisms. Extrinsic factors that encroach upon the subacromial space and contribute to bursal side compression of the rotator cuff tendons include anatomical variants of the acromion, alterations in scapular or humeral kinematics, postural abnormalities, rotator cuff and scapular muscle performance deficits, and decreased extensibility of pectoralis minor or posterior shoulder. A unique extrinsic mechanism, internal impingement, is attributed to compression of the posterior articular surface of the tendons between the humeral head and glenoid and is not related to subacromial space narrowing. Intrinsic factors that contribute to rotator cuff tendon degradation with tensile/shear overload include alterations in biology, mechanical properties, morphology, and vascularity. The varied nature of these mechanisms indicates that rotator cuff tendinopathy is not a homogenous entity, and thus may require different treatment interventions. Treatment aimed at addressing mechanistic factors appears to be beneficial for patients with rotator cuff tendinopathy, however, not for all patients. Classification of rotator cuff tendinopathy into subgroups based on underlying mechanism may improve treatment outcomes.

Pain relief, motion, and function after rotator cuff repair or reconstruction may not persist after 16 years

BACKGROUND

Short- to medium-term rotator cuff repair reportedly relieves pain in 82% to 97% of patients and provides normal or almost normal shoulder function in 82% to 92%. However, it is unknown whether pain relief and function persist long term.

QUESTIONS/PURPOSES

We asked whether, after rotator cuff repair or reconstruction, pain relief, ROM, shoulder strength, and function remained over the long term.

PATIENTS AND METHODS

We retrospectively reviewed 75 patients who underwent rotator cuff repair between 1980 and 1989. There were 55 men and 20 women. Their mean age at surgery was 52 years. The minimum followup was 16 years (mean, 20 years; range 16-25 years).

RESULTS

Twenty-eight of the 75 patients (37%) had persistent relief of pain lasting for 20 years. In the remaining 47 patients, alleviation of pain lasted, on average, 14 years (range, 0-24 years). Mean flexion and abduction strength increased postoperatively but during long-term followup decreased to less than preoperative levels. External rotation also decreased. At the last followup, the Constant-Murley score averaged 66 (range, 10-98) in men and 60 (range, 29-89) in women. In the Simple Shoulder Test questionnaire, the mean number of yes answers was eight of 12. Of the 75 patients, 32 (43%) reported impairment in activities of daily living owing to an index shoulder complaint. Severe degenerative changes of the glenohumeral joint were evident in 14 patients (19%).

CONCLUSIONS

The early high functional scores after primary rotator cuff repair or reconstruction of the types we performed in the 1980s did not persist. The function achieved postoperatively was lost, as ROM and strength decreased to less than preoperative values. However, alleviation of pain was long-standing in most patients. Based on our data, we should warn patients to expect less than permanent relief with those repairs. We cannot say whether the same will apply to currently performed types of repairs.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Acromioclavicular joint problems in athletes and new methods of management

The acromioclavicular (AC) complex consists of bony and ligamentous structures that stabilize the upper extremity through the scapula to the axial skeleton. The AC joint pathology in the athlete is generally caused by 1 of 3 processes: trauma (fracture, AC joint separation, or dislocation); AC joint arthrosis (posttraumatic or idiopathic); or distal clavicle osteolysis. This article presents systematically the relevant anatomy, classification, evaluation, and treatment of these disorders. Management of AC joint problems is dictated by the severity and chronicity of the injury, and the patient's needs and expectations.

Radiological features of osteoarthritis of the acromiclavicular joint and its association with clinical symptoms

PURPOSE

To determine whether increasing age is associated with increased radiological features of osteoarthritis of the acromioclavicular joint (ACJ) in a general population, and whether clinical symptoms correlate with radiological features.

METHODS

Anteroposterior and axillary shoulder radiographs of 240 patients aged 20 to 80 years were randomly selected. The presence of stigmata of osteoarthritis of the ACJ including sclerosis, cysts, lysis, and osteophytes were recorded, and the width of the ACJ was measured. To determine the correlation between clinical symptoms and radiological features, the same radiological features were assessed for 100 further patients who had undergone either arthroscopic subacromial decompression (ASD) alone (n=50) or ASD plus ACJ excision (n=50, age-matched controls) based on clinical examination.

RESULTS

Radiological features of osteoarthritis of the ACJ increased significantly with increasing age but were not related to gender or the side affected. Of the 10 features, only medial acromial sclerosis and superior clavicular osteophytes were more prevalent in patients with ASD plus ACJ excision than in those with ASD alone (p=0.016). The sensitivity, specificity, positive and negative predictive values of these features were poor. Therefore, clinical symptoms were not associated with radiological features of osteoarthritis of the ACJ.

CONCLUSION

Radiological features should only be used as an adjunct in the decision to excise the ACJ. A thorough clinical examination is crucial in the assessment of ACJ pathology.

The long-term effectiveness of steroid injections in primary acromioclavicular joint arthritis: a five-year prospective study

We evaluated the long-term benefits of steroid injection in 25 shoulders in 20 consecutive patients (average age, 55 years) with primary acromioclavicular arthritis. Minimum follow-up was 5 years. The mean preinjection Constant score (61 points) improved at 6 months to 81 points, (mean difference, 19.36; P < .01). Improvement at 12 months (mean, 86 points) was also significant vs the 6-month score (P = .001). The mean score at 5 years (81 points) was a significant deterioration vs the 12-month score (P = .01) but still a significant improvement vs the preinjection scores (P < .0005). Younger patients had greater improvement in the objective score (range of movement and power; r = -0.47; P = .01), as did women (r = 0.405; P = .05). Local steroid injection is an effective treatment for primary isolated acromioclavicular arthritis. Improvement continues for at least 12 months. The benefit is felt up to 5 years. Pain relief tends to diminish long-term.

Temporal variations in a modified Neer impingement test can confound clinical interpretation

High variability in the time required for patients to have substantial pain relief after Neer-type subacromial impingement tests might help explain conflicting data regarding their effectiveness in guiding treatment and predicting surgical outcomes. To focus on quantifying temporal variability associated with a modified (local anesthetic and corticosteroid) impingement test, we hypothesized that substantial pain relief (greater than 75% reduction) can occur beyond the 10-minute interval many clinicians use for determining results of this test. Fourteen females and 12 males (mean age, 55.6 years) who received subacromial injections for Stage II impingement completed 10-cm visual analog scales for pain at 5, 10, 20, 30, and 40 minutes postinjection. There were 11 patients (42%) who attained at least 75% relief by 10 minutes compared with nine (35%) additional patients who subsequently attained 75% relief after 10 minutes. On average, 75% reduction in pain did not occur until after 30 minutes postinjection. Data analysis also revealed two groups: (1) rapid responders with greater than 50% pain relief by 10 minutes; and (2) delayed responders with greater than 50% pain relief after 10 minutes. Assessing pain at 10 minutes for a Neer-type impingement test can fail to accurately determine a positive test in a substantial percentage of patients.

Acromioclavicular joint injury: enhanced technique of examination with dynamic maneuver

Acromioclavicular (AC) sprains can be graded in 3 to 6 different types according to Tossy or Rockwell, respectively. In mild sprains (Tossy and Rockwell I), movements in the AC joint are minimal, because the coraco-clavicular ligaments are intact. In these patients, stress radiography is usually normal, and sonographic examination at rest can be normal as well, showing minimal or no displacement between the 2 extremities of the bones. We present a simple dynamic maneuver to enhance the diagnosis of these mild sprains known as the cross-arm maneuver, in which the hand is placed on the opposite shoulder. The dynamic sonographic examination during this maneuver clearly shows abnormal movements in the clavicle's extremity, which "falls down" to the acromion in the cross-arm position and is raised and pulled from the acromion at rest. The maneuver is very easy to perform and may be useful when a mild AC joint sprain is suspected.

Disorders of the acromioclavicular joint

The acromioclavicular joint is a frequent source of shoulder pain.This article reviews acromioclavicular separations and other disorders affecting the joint and its surrounding structures.

Diagnostic value of physical tests for isolated chronic acromioclavicular lesions

PURPOSE

Chronic acromioclavicular joint lesions are a common source of pain and disability in the shoulder. The goal of this study was to evaluate diagnostic values of physical tests for isolated, chronic acromioclavicular joint lesions.

STUDY DESIGN

A retrospective case-control study.

METHODS

Between 1994 and 2002, 35 patients underwent a distal clavicle excision for isolated acromioclavicular joint lesions. The results of 3 commonly used examinations for acromioclavicular joint lesions were calculated for sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy.

RESULTS

The cross body adduction stress test showed the greatest sensitivity (77%), followed by the acromioclavicular resisted extension test (72%) and active compression test (41%). The active compression test had the greatest specificity (95%). All tests had a negative predictive value of greater than 94%, but the positive predictive value was less than 30% for all tests. The active compression test had the highest overall accuracy (92%), followed by the acromioclavicular resisted extension test (84%) and the cross arm adduction stress test (79%). Combinations of the tests increased the diagnostic values for chronic acromioclavicular joint lesions.

CONCLUSIONS

These tests have utility in evaluating patients with acromioclavicular joint pathologic lesions, and a combination of these physical tests is more helpful than isolated tests.

Isolated Acromioclavicular Joint Pathology in the Symptomatic Shoulder on Magnetic Resonance Imaging

The acromioclavicular (AC) joint is a synovial joint that is predisposed to painful syndromes because of mechanical stress or developmental variation. It is often overlooked in the evaluation of patients with shoulder pain, however. Isolated AC joint pathology was studied on magnetic resonance imaging scans of patients with symptoms suggesting rotator cuff pathology. The conditions identified included osteoarthritis, distal clavicle osteolysis, and os acromiale syndrome.

Joint compression alters the kinematics and loading patterns of the intact and capsule-transected AC joint

High compressive loads are transmitted through the shoulder across the acromioclavicular (AC) joint to the axial skeleton during activities of daily living and can lead to early joint degeneration or instability. The objective of this study was to quantify the effect of joint compression on the biomechanics of the intact and capsule-transected AC joint during application of three loading conditions. A robotic/universal force-moment sensor testing system was utilized to apply an anterior, posterior or superior load of 70 N in combination with 10 or 70 N of joint compression to fresh-frozen cadaveric shoulders (n=12). The application of joint compression to the intact AC joint decreased the posterior translation in response to a posterior load (-6.6+/-2.5 vs -3.7+/-1.0 mm, p<0.05). Joint compression also decreased the in situ force in the superior AC capsule by 10 N while increasing the joint contact force by 20 N for all loading conditions (p<0.05). The application of joint compression to the capsule-transected AC joint significantly decreased the amount of posterior and superior translation during posterior (-12.7+/-6.1 vs -5.5+/-3.2 mm, p<0.05) and superior (5.3+/-2.9 vs 4.2+/-2.3 mm, p<0.05) loading, respectively, while significantly increasing the coupled translations (anterior-posterior, superior-inferior or proximal-distal) in all loading conditions (p<0.05). The joint contact force also significantly increased by 20 N for all loading conditions (p<0.05). This quantitative data suggests: (1) common surgical techniques such as distal clavicle resection, which initially reduce painful joint contact, may cause unusually high loads to be supported by the soft tissue structures at the AC joint; and (2) compressive loads transmitted across a capsule-transected AC joint could be concentrated over a smaller area due to the increased coupled motion and joint contact force.

Radiographic evaluation of the acromioclavicular and sternoclavicular joints

Plain radiography is useful for the initial assessment of suspected disorders of the sternoclavicular and acromioclavicular joints. Other modalities are often required to further assess more complex pathologies involving these joints, however. Ultrasound has been described as a screening tool to assess possible sternoclavicular joint dislocation; however, it is usually used only if CT and MRI are not readily available. It has also been used to confirm intraoperative relocation. Ultrasound has a limited role in the evaluation of the AC joint, where it is most useful to exclude the presence of joint inflammation. If joint fluid is detected sonographically, it is considered a nonspecific finding, which could represent active inflammation or simply joint effusion due to degenerative arthrosis. CT allows for excellent visualization of the articular surfaces, osseous changes, subtle or complex fractures, and joint malalignment, with a rapid scan time, making it particularly helpful in the work up of trauma patients. With its multiplanar capabilities and superior soft-tissue resolution, MRI is a very effective modality for characterizing soft-tissue injuries, inclusive of ligamentous tears and cartilaginous injuries. In the specific case of posterior sternoclavicular dislocations, both CT and MR angiography can be very helpful in elucidating occult associated vascular injury.

The role of the acromioclavicular joint in impingement syndrome

Although AC pathology usually represents a late manifestation of outlet impingement, it typically presents as a cause of pain that is resistant to nonoperative and operative measures designed to treat purely anterior acromial pathology. The bursitis that occurs with AC joint impingement may be indistinguishable from anterior acromial impingement on clinical presentation; however, physical examination, diagnostic injection, and radiographic evaluation are generally sufficient to establish the diagnosis of AC joint impingement. Nonoperative measures are indicated for the treatment of acute bursitis, although operative intervention may be necessary in cases of large, distally projecting osteophytes in the presence of AC joint degeneration. Acromioclavicular pathology, when present, should be addressed at the time of subacromial decompression, and may involve distal clavicular resection, beveling of the AC joint, or excision of marginal osteophytes. The results of surgery to address the AC contribution to impingement are generally favorable; future investigation may further clarify the role of coplaning and its potential contribution to continued postoperative AC pain and symptomatic instability.

Radiographic findings associated with symptomatic rotator cuff tears

This study compared shoulder radiographs of patients with a documented rotator cuff tear with those of asymptomatic age-matched controls. Radiographs of 40 subjects with documented rotator cuff tears were evaluated along with similar films of 84 asymptomatic age-matched controls. Three radiographs were taken of each shoulder: (1) acromioclavicular joint view, (2) anterior-posterior view with 30 degrees of external rotation, and (3) supraspinatus outlet view. Two fellowship-trained radiologists interpreted 14 radiographic areas in a blinded fashion. Inspection of the greater tuberosity showed large positive abnormal ratings for sclerosis, osteophytes, subchondral cysts, and osteolysis. No association was noted between acromial morphology and rotator cuff tears. These results indicate that shoulder radiographs of subjects with a documented rotator cuff tear have greater tuberosity radiographic abnormalities that are not noted in asymptomatic subjects without a rotator cuff tear. No relationship was found between tear length and any of the degenerative conditions.

Bony injuries of the shoulder

The complex anatomy and functioning of the shoulder may challenge the radiologist. In this review the patterns of injury and radiographic findings for bony injuries of the shoulder are illustrated. The radiographic and cross-sectional imaging findings in fractures of the clavicle, scapula, and proximal humerus and in dislocations of the sternoclavicular, acromioclavicular, and glenohumeral articulations are discussed.

Acromioclavicular joint injuries: identifying and treating 'separated shoulder' and other conditions

The acromioclavicular (AC) joint is vulnerable to injury in collision sports and in activities requiring repetitive overhead motions. The spectrum of injury includes sprains and osteoarthritis of the AC joint and osteolysis and fracture of the distal clavicle. With the exception of severe sprains and fractures, most conditions can be managed nonoperatively. The key to successful treatment is prompt and accurate recognition of the severity of AC injuries.

Detection of acromioclavicular joint pathology in asymptomatic shoulders with magnetic resonance imaging

The purpose of this study was to determine the prevalence of acromioclavicular joint (ACJ) arthritis with magnetic resonance imaging (MRI) evaluation in asymptomatic patients. Fifty shoulders in 42 patients were evaluated with the use of standard MRI techniques. There were 18 men and 24 women with an average age of 35 years (range, 19 to 72). ACJ arthritic changes were graded on a scale from 1 to 4 (none, mild, moderate, and severe), based on the amount of subacromial fat effacement, joint space narrowing, irregularity, capsular distension, and osteophyte formation. Forty-one (82%) of 50 shoulders had abnormalities consistent with arthritis on MRI. Patients were divided into two groups according to age: those older than 30 years and those 30 years old or younger. In the 30-and-under age group, 68% of the shoulders had arthritic changes, whereas in the over-30 age group, 93% had arthritic changes. Furthermore, in a comparison of the two groups, more advanced arthritic changes were found in the over-30 age group (P <.05). Clinical decisions to resect the ACJ should correlate the physical examination with the MRI findings because many patients may be clinically asymptomatic.

Acromioclavicular joint injuries

Injuries to the acromioclavicular joint are common, and most can be treated nonoperatively. Appropriate treatment depends on accurate diagnosis and appreciation of the classification of these various injuries. Descriptions of the commoner acromioclavicular joint injuries, details of the nonoperative treatment, and indications for surgical treatment are reviewed.

MR observations of postraumatic osteolysis of the distal clavicle after traumatic separation of the acromioclavicular joint

PURPOSE

The purpose of this work was to characterize the MR features of post-traumatic osteolysis of the distal clavicle in patients who have sustained a previous separation of the ipsilateral acromioclavicular (AC) joint.

METHOD

We studied eight male patients (mean age 25 years) with intractable pain in the AC joint after sustaining a traumatic joint separation. With use of the Rockwood classification, the separations were classified as Type 1 in one patient, Type 2 in two patients, and Type 3 in five patients. The MR studies were evaluated for periarticular soft tissue swelling, cortical irregularity defined as thinning or absence of portions of the cortex in the acromial and clavicular articular surfaces, hypertrophic osseous changes, periostitis, bone marrow edema, periarticular cyst-like changes, and joint space widening exceeding 6 mm. Radiographs were evaluated independently of the MR studies. Osteolysis of the distal clavicle was confirmed pathologically in seven patients and with surgery in one patient.

RESULTS

The incidence of osteolysis in patients who have had a previous AC joint separation was estimated to be approximately 6%. Observations on MRI included soft tissue swelling, bone marrow edema in the distal clavicle, and cortical irregularity associated with periarticular cyst-like erosions in eight patients, joint space widening in six patients, clavicular periostitis in three patients, and marrow edema in the cromion in five patients. Only one patient had osteophyte formation. Radiographic observations of periarticular soft tissue swelling, osteopenia of the distal clavicle, articular erosions, and joint space widening allowed diagnosis in only four patients prospectively.

CONCLUSION

The MR features of posttraumatic osteolysis are characteristic of this process. We advocate the use of MRI in patients with chronic AC joint pain who have had a prior AC joint dislocation, particularly if follow-up radiographs are nonspecific, equivocal, or do not indicate the presence of secondary osteoarthritis.

Radiographic joint space in rheumatoid acromioclavicular joints: a 15 year prospective follow-up study in 74 patients

OBJECTIVE

To evaluate radiographically the acromioclavicular joint space in patients with long-term rheumatoid arthritis (RA).

METHODS

A cohort of 74 patients with RA was followed prospectively for 15 yr. At the end point, 148 shoulders were radiographed with a standard method. The acromioclavicular (AC) joint space was examined from the radiographs with a method developed previously for population studies; the joint space was measured at its superior and inferior border, and the average of the two measurements, the integral space, calculated.

RESULTS

Mean AC joint space in RA patients was 4.9 (S.D. 3.7), range 0-20.5 mm; 6.2 mm (S.D. 5.1) in men and 4.5 mm (S.D. 3. 0) in women. An AC joint space wider than 7 mm in men was found in 11 (31%) out of 36 joints and wider than 6 mm in women in 17 (15%) out of 112 joints. Joint space widening was associated (r=0.87, 95% CI 0.82-0.90) with increasing destruction (Larsen grading) of the joint and it seems to be an inevitable consequence of AC joint affection in RA. Joint space widening is more progressive on the caudal side because of the nature of the erosive destruction. Degeneration with joint space narrowing was observed in 8 (11%) patients (11 joints, 7%; three bilateral).

CONCLUSIONS

The largest value of the joint space may be used when evaluating rheumatoid AC joint space. In RA patients, a joint space of >7 mm in men and >5 mm in women is a sign of destructive AC joint affection.

Painful conditions of the acromioclavicular joint

The acromioclavicular (AC) joint may be affected by a number of pathologic processes, most commonly osteoarthritis, posttraumatic arthritis, and distal clavicle osteolysis. The correct diagnosis of a problem can usually be deduced from a thorough history, physical examination, and radiologic evaluation. Asymptomatic AC joint degeneration is frequent and does not always correlate with the presence of symptoms. Selective lidocaine injection enhances diagnostic accuracy and may correlate with surgical outcome. Nonoperative treatment is helpful for most patients, although those with osteolysis may have to modify their activities. In appropriately selected patients, open or arthroscopic distal clavicle resection is necessary to relieve symptoms. Recent biomechanical and clinical data emphasize the importance of capsular preservation and minimization of bone resection; however, the optimal amount of distal clavicle resection remains elusive. Patients with AC joint instability have poor results after distal clavicle resection.

The influence of acromioclavicular joint morphology on rotator cuff tears

A detailed anatomic study of 123 shoulders was performed to define the location of the acromioclavicular (AC) joint within the supraspinatus outlet and to determine the correlation of AC joint morphologic characteristics with the presence of full-thickness rotator cuff tears (RCTs). The presence, location, and extent of RCTs were first documented for each shoulder, and 2 anatomic landmarks consisting of the anterolateral acromial corner and the inferior midpoint of the AC joint were identified and their positions digitized in 3 dimensions to calculate outlet space and clearance and AC joint locations. High resolution x-ray films were then obtained to determine the extent of degenerative changes including the location and size of inferior osteophytes and joint space. These specimens were cleaned of all soft tissues, and additional measurements were made. All data were entered into a computerized database and analyzed with respect to age, sex, and the presence of RCT. Comparison of age-matched RCT versus non-RCT groups revealed no significant differences in the position of the AC joint within the supraspinatus outlet. When AC joint morphologic characteristics were compared with those of a nontear, age-matched group, no significant differences with regard to joint space narrowing were found, but significantly larger and greater number of osteophytes were identified on both sides of the joint in the RCT group. In conclusion, the position of the AC joint is fairly constant within the supraspinatus outlet and does not appear to predispose to RCTs. The morphology of the AC joint contribution of the tears seems to be acquired in nature rather than inherent in its location within the outlet.

The acromion: morphologic condition and age-related changes. A study of 420 scapulas

Two hundred ten specimens (420 scapulas) from the Hamann-Todd Osteological Collection at the Cleveland Museum of Natural History were evaluated to determine the influence of age on acromial morphologic condition. Equal numbers of specimens from female and male and black and white subjects were evaluated. The length, width, and anterior thickness of the acromion and the acromial facet of the acromioclavicular joint were measured with digital calipers, examined visually, and evaluated radiographically. Distribution of acromial morphologic types was type I, (flat) 32%, type II (curved), 42%, and type III (hooked), 26%. Analysis of the data revealed no consistent, statistically significant impact of age on morphologic condition. The incidence of os acromiale was 8% (17 of 210), with 7 (41%) of 17 specimens having bilateral involvement. Mean acromial dimensions in men were length = 48.5 mm, width = 19.5 mm, and anterior thickness = 7.7 mm. Mean dimensions in women were length = 40.6 mm, width = 18.4 mm, and thickness = 6.7 mm. Multiple regression analysis revealed no significant changes in any dimension with increasing age. Observation of the acromial facet of the acromioclavicular joint revealed 49% were medially inclined, 48% were vertically inclined, and only 3% were laterally inclined in relationship to the sagittal plane. A statistically significant age-related increase in degenerative changes was noted. Anterior acromial spur formation as determined by visual inspection of the acromion was observed in 7% of specimens from patients younger than 50 years compared with 30% of specimens from patients older than 50 years (p < 0.05). Spur formation on the anterior acromion is an age-dependent process. Acromial morphologic condition as evaluated by outlet radiographs is independent of age and appears to be a primary anatomic characteristic. The variations seen in acromial morphologic condition are not acquired from age-related changes and spur formation and thus contribute to impingement disease independent of and in addition to age-related processes.

Surgical resection of the distal clavicle

Distal clavicle resection is frequently performed for persistent acromioclavicular pain. However, patient outcome after this procedure has not been well described. The results of subjective and objective retrospective analysis of 23 open distal clavicle resections in 21 patients are reported. Patients were evaluated with a questionnaire, roentgenographs, physical examination, and isokinetic muscle strength testing at an average of 30 months after surgery. Eighteen of 23 shoulders had good or excellent postoperative ratings. All patients had normal motion. No significant weakness of the operated shoulder was seen on objective muscle testing when compared with the unoperated shoulder. The average preoperative Hospital for Special Surgery score was 34, and the average postoperative score was 84. Age and hand dominance were unrelated to postoperative outcomes. Less predictable results were obtained in patients with workmen's compensation and in those patients involved in litigation. Open distal clavicle resection yields good to excellent results in properly selected patients and does not create significant subjective or objective weakness.

Arthroscopic resection of the distal clavicle with a superior approach

Forty-one patients (41 shoulders) with acromioclavicular joint disease refractory to conservative treatment underwent arthroscopic distal clavicle resection. Thirty-one men and 10 women with an average age of 32 years were studied. The dominant extremity was involved in 68% of the patients. At an average follow-up period of 31 months (range 24 to 49 months), 18 excellent, 16 good, and seven poor results were found. Twenty-seven (93%) of 29 shoulders with acromioclavicular arthritis or osteolysis of the distal clavicle went on to have satisfactory results compared with only seven (58%) of 12 shoulders with previous grade II acromioclavicular separations or acromioclavicular hypermobility. Total amount of bone removal did not correlate with success, if the resection was even. Five reoperations were done; one uneven resection was revised with arthroscopy, and four shoulders underwent acromioclavicular stabilization procedures. The high failure rate in patients with even subtle acromioclavicular instability (42%) suggests that in these cases formal stabilization with ligament reconstruction should be considered in addition to resection of the distal clavicle.

Arthroscopic resection of the outer end of the clavicle from a superior approach: a critical, quantitative, radiographic assessment of bone removal

The technique of arthroscopic resection of the outer end of the clavicle through a superior approach is evaluated to determine whether adequate bone removal can be achieved. Furthermore, the results are compared with open resection. Twelve patients with osteolysis of the outer end of the clavicle refractory to conservative treatment underwent resection: six open and six arthroscopically through a superior approach. The distances from the acromial side of the AC joint to the lateral edge of the clavicle at its superior and inferior cortices were measured before and after surgery on anteroposterior radiographs. Bone removal was assessed by the difference between pre- and postoperative measurements. Satisfactory bone removal was possible arthroscopically and averaged 17 mm. This compared favorably with 18-mm average bone removal in the open group. Comparable pain relief and function were achieved in both groups. However, pain relief was achieved on average 3.4 months earlier in the arthroscopic group. Hospital stay was significantly shortened because the arthroscopic resections were outpatient procedures, whereas the open procedures had an average hospital stay of 3 days.