Post-traumatic and stress-induced osteolysis of the distal clavicle: MR imaging findings in 17 patients

Distal Clavicular Osteolysis Treated With Platelet-Rich Plasma: A Case Report

ABSTRACT

Atraumatic distal clavicular osteolysis (DCO) is a cause of shoulder pain in younger athletes, often resulting from weightlifting and activities with repetitive pressing and overhead lifting. Athletes will present with shoulder pain localized to the acromioclavicular (AC) joint, with tenderness to palpation over the joint exacerbated by provocative testing on examination. Conservative management often includes activity modification, oral analgesics, physical therapy, and corticosteroid injection. Distal clavicular osteolysis can be refractory to conservative management and these athletes are often referred for surgical consultation. Platelet-rich plasma (PRP) injections have been used to treat a wide variety of musculoskeletal injuries, but there have been no published studies assessing the efficacy of PRP injections specifically for distal clavicle osteolysis. We present a case of refractory DCO successfully treated with an ultrasound-guided PRP injection of the AC joint.

A Sports Medicine Clinician's Guide to the Diagnosis and Management of Distal Clavicular Osteolysis

ABSTRACT

Weightlifting associated shoulder injuries have seen a dramatic rise in the last 20 years. Distal clavicular osteolysis, coined weightlifter's shoulder, is one such condition caused by repetitive microtrauma to the distal clavicle with subsequent, painful development of bony erosions and resorption of the distal clavicle. Diagnosis, treatment, and prevention of this condition can be challenging. In this article, we highlight evidence-based clinical recommendations for the diagnosis and management of distal clavicular osteolysis, including specific considerations for atraumatic and posttraumatic etiologies, to help clinicians better care for their patients. Activity modification and rehabilitation are the mainstays of the initial treatment. Adjuvant treatments, such as injections or surgery, may be required in refractory cases or in certain patient populations. Early recognition and treatment of weightlifter's shoulder is essential to prevent progression to acromioclavicular joint pathology or instability and to allow for continued participation in sport-specific activities.

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.

Normal development imaging pitfalls and injuries in the pediatric shoulder

The skeletal maturation of the shoulder has been well documented on radiographic and cadaveric studies. Recent increased use of MRI has provided increased understanding of the soft-tissue and osseous changes that occur during development. Thus recognizing normal maturation, imaging manifestations and pitfalls is crucial when evaluating the pediatric shoulder joint. At birth, the humeral diaphysis, midportion of the clavicle, and the body of the scapula are ossified, while the remainder of the bones of the shoulder are composed of non-ossified cartilaginous precursors. During growth, cartilaginous apophyses and epiphyses of the shoulder develop numerous secondary ossification centers, which fuse with the primary ossification centers to form the complete bony components of the shoulder. Additionally changes in the morphology of the growth plates as well as marrow signal occur in an organized manner. This paper affords the reader with an understanding of the normal development of three major components of skeletal maturation in the shoulder: ossification centers, growth plates and marrow signal. These topics are further subdivided into the glenoid, proximal humerus and acromioclavicular joint. We also provide a focus on distinguishing normal anatomy from imaging pitfalls related to skeletal maturation.

Overuse Injuries of the Shoulder

This article discusses the most common and important overuse injuries of the shoulder with attention to MR imaging and ultrasound findings. Pathologic conditions occurring in athletes and nonathletes are included, with review of relevant anatomy, predisposing factors, and treatment considerations. Specific overuse injuries involving the rotator cuff, long head of the biceps tendon, and subacromial-subdeltoid bursa are reviewed. Impingement syndromes of the shoulder, Little Leaguer's shoulder, and stress-induced distal clavicular osteolysis are also discussed.

Diagnosis and Management of Distal Clavicle Osteolysis

Distal clavicle osteolysis is an uncommon condition that most commonly affects weight lifters and other athletes who perform repetitive overhead activity. Although this condition most commonly presents in young active men, it is becoming increasing more common in women with the rise in popularity of body building and extreme athletics. Distal clavicle osteolysis can be debilitating, especially in those with rigorous training regimens, preventing exercise because of pain with activities such as bench presses and chest flies. Aside from a careful history and physical examination, radiographic evaluation is essential in distinguishing isolated distal clavicle osteolysis from acromioclavicular joint pathology, despite a potentially similar presentation of the 2 conditions. Nonoperative therapy that includes activity modification, nonsteroidal anti-inflammatory drugs, and cortisone injections is the first-line management for this condition. Patients whose conditions are refractory to nonoperative modalities may benefit from distal clavicle resection via either open or arthroscopic techniques. Arthroscopic techniques typically are favored because of improved cosmesis and the added benefit of the ability to assess the glenohumeral joint during surgery to rule out concomitant pathology. There are varying operative techniques even within arthroscopic management, with pros and cons of a direct and an indirect surgical approach. Patients often do well after such procedures and are able to return to their preinjury level of participation in a relatively short period. [Orthopedics. 2017; 40(2):119-124.].

Biomechanical Analysis of Intra-articular Pressure After Coracoclavicular Reconstruction

BACKGROUND

Recent biomechanical and clinical studies have demonstrated the effectiveness of suture button and pulley-type fixations for surgical treatment of acromioclavicular instability. Concerns remain that such procedures can "overconstrain" (overreduce the lateral clavicle in relation to the acromion to a nonphysiological position) the joint. Purpose/Hypothesis: The purpose of this study was to investigate the intra-articular pressure of native and reconstructed acromioclavicular (AC) joints in relation to the configuration of the joint. Anatomic (0 mm), overconstrained (-3 mm), and underconstrained (+3 mm) AC joint reconstructions were simulated. The hypothesis was that reconstructions using suture pulley systems do not increase the intra-articular pressure of the AC joint.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eleven fresh-frozen cadaveric shoulders were used in this study (mean age ± SD, 60.8 ± 6.7 years). Each specimen underwent radiographic analysis by using a Zanca view to determine the basic configuration of the AC joint. A pressure Tekscan sensor was inserted in the AC joint. A servohydraulic materials testing system was used for testing. The specimens were kept in the testing machine, and the native AC position was marked at 0 mm. This allowed moving the clavicle during the surgical procedure with reference to the native anatomic position. Intra-articular pressure in the native AC joint during cyclic loading (1000 cycles; 1 Hz) was measured. After native testing, the AC ligaments and coracoclavicular ligaments were cut and reconstructed using a cortical button technique. Anatomic, -3 mm, and +3 mm positions, relative to the acromion, were cyclically loaded, and intra-articular pressure was documented.

RESULTS

According to the AC joint classification of inclination, we identified five type 1 (46%), four type 2 (36%), one type 3 (9%), and one incongruous (9%) configurations. Changes in superior displacement across the 4 conditions were not statistically significant (0.5 ± 0.8 [native], 0.01 ± 0.00 [0 mm repair], 0.02 ± 0.02 [-3 mm repair], and 0.01 ± 0.01 [+3 mm repair]; P = .162). Before testing (time point 1), pressure in the -3 mm repair (62.9 ± 70.1) differed between the native state (11.3 ± 21.8; P = .042) and the +3 mm repair (7.1 ± 18.4; P = .023). All other changes at time points 2 (after cyclic loading unloaded) and 3 (after cyclic loading loaded) in pressure were not significant. ( P = .086 and .226, respectively).

CONCLUSION

AC joint reconstruction (within -3 to +3 mm of reduction) with a coracoclavicular suture button device does not significantly increase the intra-articular pressure of the AC joint after cyclic loading in our experimental cadaveric setup.

CLINICAL RELEVANCE

Recent biomechanical and clinical studies have demonstrated the effectiveness of suture button and pulley-type fixations for coracoclavicular reconstruction of the joint. Concerns remain that such procedures would "overconstrain" the joint because of the high rigidity of these pulley systems and the preservation of the lateral clavicle. This overconstraining may potentially result in pain at the lateral end of the clavicle, osteolysis, or a later increased risk of early osteoarthritis. Therefore, our results indicate that within a range of ±3 mm to the anatomic position, overconstraining may not result in a higher intra-articular pressure.

Frequency, imaging findings, risk factors, and long-term sequelae of distal clavicular osteolysis in young patients

OBJECTIVE

Atraumatic distal clavicular osteolysis (DCO) has been described in adult male weightlifters. Our purpose was to investigate the frequency, magnetic resonance imaging (MRI) characteristics, risk factors, and long-term sequelae of DCO in young patients.

MATERIALS AND METHODS

Individuals with atraumatic DCO were identified in a retrospective review of 1,432 consecutive MRI shoulder reports in patients between 13 and 19 years of age. MRI findings of DCO, association with athletic activity, short-term clinical outcome after 3-6 months, and long-term clinical and MRI outcome after 2 years were analyzed. A pre-MRI questionnaire assessed the patients' athletic history including overhead activity and weightlifting.

RESULTS

At a mean age of 15.9 years, 6.5 % (93/1432) of patients had atraumatic DCO, and 24 % were females. The combination of an overhead sport (basketball, volleyball, tennis, swimming) and supplemental weight training was a risk factor for DCO (odds ratio = 38, p = 0.01). Ninety-three percent of patients responded to conservative therapy. On follow-up imaging, 71 % of DCO patients had acromioclavicular (AC) joint osteoarthritis (vs. 35 % in controls, p = 0.006); 79 % had flattening of the distal clavicle and interval widening of the AC joint to a mean of 5.0 mm (compared to 2.4 mm in controls, p < 0.001). Severity of DCO edema was associated with pain (p < 0.02) at initial presentation and with AC joint osteoarthritis (p = 0.004) on follow-up.

CONCLUSION

In athletic teenagers, the combination of weightlifting and overhead activity is a risk factor for atraumatic DCO, and females are affected in 24 %. Long-term sequelae include widening of the AC joint and AC joint osteoarthritis.

Distal Clavicle Osteolysis after Modified Weaver-Dunn's Procedure for Chronic Acromioclavicular Dislocation: A Case Report and Review of Complications

Distal clavicle osteolysis after acromioclavicular joint stabilization has only been described after the use of hardware for clavicle stabilization or synthetic graft causing a foreign body reaction. This paper reports a very rare case of distal clavicle osteolysis after modified Weaver-Dunn procedure for the treatment of chronic acromioclavicular joint dislocation. The paper also provides a comprehensive review of complications of this surgical technique and discusses a potential vascular etiology and preventive strategies aimed at avoiding clavicle osteolysis.

Clinical update: MR imaging of the shoulder

Magnetic resonance imaging has become an important diagnostic adjunct in the evaluation of shoulder conditions, and the technology continues to evolve. Direct magnetic resonance arthrography can improve detection of labral and rotator cuff pathology, especially partial thickness tears of the rotator cuff. Special positioning, such as abducted-externally rotated views, improves visualization of the rotator cuff and posterior superior labrum in throwing athletes. Diagnosis-specific sequencing such as fat suppression, spin-echo and proton-density techniques, and higher power magnets (3.0 T) allow for an unprecedented level of soft tissue detail. Clinical expertize is required to differentiate between normal anatomic variants, incidental findings, and true pathology. Although magnetic resonance imaging findings may be diagnostic in some cases, clinical correlation with history and physical examination findings is critical.

MR imaging appearances of acromioclavicular joint dislocation

The key structures involved in dislocation of the acromioclavicular joint (ACJ) are the joint itself and the strong accessory coracoclavicular ligament. ACJ dislocations are classified with the Rockwood system, which comprises six grades of injury. Treatment planning requires accurate grading of the ACJ disruption, but correct classification can be difficult with clinical assessment. Magnetic resonance (MR) imaging has a well-established role in evaluation of ACJ pain. MR imaging performed in the coronal oblique plane parallel to the distal clavicle allows assessment of the acromioclavicular and coracoclavicular ligaments owing to its in-plane orientation in relation to these structures. This technique enables distinction between grade 2 and grade 3 injuries, which can be difficult with conventional clinical and radiographic evaluation. In addition, diagnosis of grade 1 injuries is possible by demonstration of a ruptured superiodorsal acromioclavicular ligament. Resultant thickening of the acromioclavicular or coracoclavicular ligament allows identification of chronic ACJ injuries.

Miscellaneous conditions of the shoulder: anatomical, clinical, and pictorial review emphasizing potential pitfalls in imaging diagnosis

The purpose of this article is to review the key imaging findings in major categories of pathology affecting the shoulder joint including hydroxyapatite deposition disease, rotator cuff interval pathology, acromioclavicular joint pathology, glenohumeral osteoarthrosis, and synovial inflammatory processes, with specific emphasis on findings that have associated pitfalls in imaging diagnosis. The pathophysiology and clinical manifestations of the above mentioned categories of pathology will be reviewed, followed in each section by a detailed pictorial review of the key imaging findings in each category including plain film, computed tomography, and magnetic resonance imaging findings as applicable. Imaging challenges that relate to both diagnosis and characterization will be addressed with each type of pathology. The goal is that after reading this article, the reader will be able to recognize the key imaging findings in major categories of pathology affecting the shoulder joint and will become familiar with the potential pitfalls in their imaging diagnosis.

Imagerie des traumatismes de l’épaule

The goals of this article are: 1) to review the different radiographic projections commonly used at the time of initial imaging evaluation of patients presenting with traumatic injuries of the shoulder; 2) to review the indications and findings of cross-sectional imaging modalities in the assessment of shoulder trauma; 3) to recognize the main anatomical lesions secondary to traumatic injuries of the shoulder.

Distal clavicular osteolysis: MR evidence for subchondral fracture

PURPOSE

To investigate the association between distal clavicular osteolysis and subchondral fractures of the distal clavicle at MRI.

MATERIALS AND METHODS

This study was approved by the hospital human research committee, which waived the need for informed consent. Three radiologists retrospectively analyzed 36 shoulder MR examinations in 36 patients with imaging findings of distal clavicular osteolysis. The presence of a subchondral fracture of the distal clavicle, abnormalities of the acromioclavicular joint, rotator cuff tears and labral tears were assessed by MRI. These cases were then compared with 36 age-matched controls.

RESULTS

At MRI, 31 of 36 patients (86%) had a subchondral line within the distal clavicular edema, consistent with a subchondral fracture. Of the 36 patients, 32 (89%) had fluid in the acromioclavicular joint, while 27 of 36 patients (75%) had cysts or erosions in the distal clavicle. There were 13 patients (36%) with associated labral tears, while eight patients (22%) had partial-thickness rotator cuff tears. In the control group one of 36 (3%) had a subchondral line (P<0.05), while ten of 36 (28%) had rotator cuff tears and 13 of 36 (36%) had labral tears. These latter two were not statistically significant between the groups.

CONCLUSION

A distal clavicular subchondral fracture is a common finding in patients with imaging evidence of distal clavicular osteolysis. These subchondral fractures may be responsible for the propensity of findings occurring on the clavicular side of the acromioclavicular joint.

MR imaging of the rotator cuff

MR imaging is the optimal method for evaluating suspected rotator cuff pathology. Current techniques of fast spin-echo imaging without and with fat suppression allow accurate identification and characterization of tendinous and myotendinous abnormalities of the rotator cuff. Impingement disorders, tendon degeneration, instability,and trauma comprise the multifactorial nature of rotator cuff disease. This article addresses the role of MR imaging in evaluating the rotator cuff and the importance of MR imaging in identifying other lesions that may mimic rotator cuff pathology. A rationale for protocol design, including MR arthrography and the use of specialized positioning, such as abduction and external rotation (ABER), are discussed.

[Distal clavicle edema]

PURPOSE

Distal clavicle marrow edema: frequency, MRI in the early stage and macroscopic correlation to the bone marrow distribution and to evaluate frequency and diagnostic criteria of a posttraumatic clavicula disorder with an edema pattern on MRI. An additional macroscopic study of the clavicle should elucidate anatomic peculiarities which could explain the reaction of the distal clavicle.

MATERIAL AND METHODS

285 MRI of traumatized patients were analyzed for edema pattern of the distal clavicle. Pattern A edema within the clavicle and the acromion was distinguished from pattern B edema within the clavicle only. Dissection in 20 cadavers should reveal vascular peculiarities and the bone marrow distribution within clavicle and acromion or vascular peculiarities.

RESULTS

In 38 patients (13,3%) we found edema within the distal clavicle. Pattern A was found in 28 (9,8%) and pattern B in 10 patients (3,5%). Pattern A was usually associated with swelling of the AC joint (27 out of 28). Other injuries were not evident. 18 cadavers showed hematopoietic marrow within the distal clavicle and fatty marrow within the acromion.

CONCLUSION

The distal clavicle can frequently react with edema pattern after trauma without evidence for another injury. Distinguish in cases with and cases without synovitis of the AC joint could have impact on therapy. A peculiar vascular supply of the distal clavicle could not be found.

Osteolysis of the Distal Clavicle: Serial Improvement and Normalization of Acromioclavicular Joint Space with Conservative Care

OBJECTIVE

To discuss a case of osteolysis of the distal clavicle (ODC) in a 29-year-old male chiropractic student who showed interval radiographic and clinical evidence of healing.

CLINICAL FEATURES

The patient complained of intermittent left-sided shoulder pain of 8 months' duration that was exacerbated while performing spinal-manipulative procedures. A radiographic examination showed changes consistent with osteolysis involving the distal clavicle.

INTERVENTION AND OUTCOME

A conservative treatment regimen of physiotherapy, nutritional supplementation, and activity modification resulted in an interval reduction in symptomatology and radiographic findings on serial examinations, ultimately resolving both abnormal clinical and radiographic findings after approximately 14 months of treatment. We specifically observed normalization of the acromioclavicular (AC) joint dimension.

CONCLUSIONS

In contrast to the posttreatment radiographic outcome seen in our patient, ODC classically does not result in complete resolution of radiographic findings or normalization of AC joint dimension, and such radiographic normalization of joint space is currently not reported in the literature. This case report serves to document and to show this unique occurrence.

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.

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.

Protocols in sports magnetic resonance imaging

Magnetic resonance imaging, with its multiplanar imaging capability and superior soft-tissue contrast, has become the preferred method for imaging sports-related injuries. Advances in gradient technology, receiver coils, and imaging software have allowed the imaging of the injured athlete to take place quickly and at high resolution. Understanding the tissues being imaged, the underlying anatomy, and the capabilities of today's scanners is crucial to the design of intelligent and efficient protocols.

Magnetic resonance imaging of the shoulder: rotator cuff

Magnetic resonance imaging has proven to be useful in the assessment of rotator cuff injuries. Improvements in magnetic resonance techniques, including fast spin-echo imaging and fat saturation, have facilitated demonstration of tendinous abnormalities of the rotator cuff. Rotator cuff disease is multifactorial. Primary impingement within the coracoacromial arch, degeneration of the rotator cuff tendons, trauma, and glenohumeral instability may be contributing factors. Shoulder pain in athletes can be related to acute myotendinous and muscle injuries, which can be easily detected using magnetic resonance imaging.

Radiologic case study. Stress-induced osteolysis of the distal clavicle

Repetitive stress-induced osteolysis of the distal clavicle occurs in athletes who engage in upper extremity weight strengthening exercises and occupational overuse. Repetitive microtrauma is believed to cause microfractures and bone resorption with local pain. Conservative treatment usually is effective. If conservative treatment is unsuccessful. excellent outcomes can be expected after open or arthroscopic resection of the distal clavicle.

Upper extremity injuries associated with strength training

Most injuries sustained during strength training are mild strains that resolve with appropriate rest. More severe injuries include traumatic shoulder dislocations, tendon ruptures of the pectoralis major, biceps, and triceps; stress fractures of the distal clavicle, humerus, radius, and ulna; traumatic fractures of the distal radius and ulna in adolescent weightlifters; and compressive and stretch neuropathies. These more severe injuries are usually the result of improperly performing a strength training exercise. Educating athletes regarding proper strength-training techniques serves to reverse established injury patterns and to prevent these injuries in the first place. Recognizing the association of anabolic steroid use to several of the injury patterns further reinforces the need for medical specialists to counsel athletes against their use. With the increasing use of supplements such as creatine, the incidence and nature of strength-training injuries may change further. Greater emphasis on the competitive performance of younger athletes undoubtedly will generate enthusiasm for strength training at earlier ages in both sexes. The importance of proper supervision of these young athletes by knowledgeable persons will increase. As the popularity of strength training grows, there will be ample opportunity to continue to catalog the injury patterns associated with this activity.

Posttraumatic osteolysis of the distal clavicle: analysis of 7 cases and a review of the literature

OBJECTIVE

To discuss the clinical manifestation, radiographic features, and treatment of 7 cases of posttraumatic osteolysis of the distal clavicle. Also, to furnish evidence indicating that the current terminology for this disorder is ambiguous and to propose a new classification system.

CLINICAL FEATURES

Three cases resulted from acute trauma, and 4 cases were caused by sports-related repetitive microtrauma. All the cases involved young male patients who had similar clinical presentations that included shoulder pain with decreased shoulder range of motion. Radiographic findings ranged from small erosive changes to aggressive osteolysis of the distal clavicle.

INTERVENTION AND OUTCOME

All the patients were treated with conservative care consisting of sling immobilization, ice, various physiotherapeutic modalities, and mobilization exercises. The patients that followed through with care showed clinical improvement within 3 months. Follow-up radiographic examinations, when performed, demonstrated reconstitution of the distal clavicle of various degrees, although lagging behind clinical evidence of improvement.

CONCLUSION

Traumatic osteolysis of the distal clavicle may result from acute trauma or repetitive microtrauma. Radiographic changes are varied, including irregularity of the distal clavicle, cystic erosions, and blatant osteolysis. Positive outcomes may be achieved with conservative care; however, patient compliance plays a fundamental role in the overall prognosis.

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.