Distal Clavicle Osteolysis 

Updated: Jul 27, 2017
Author: Brett D Owens, MD; Chief Editor: S Ashfaq Hasan, MD 

Overview

Background

Distal clavicle osteolysis (DCO) is a pathologic process involving resorption of subchondral bone in the distal clavicle. The condition usually presents as pain localized to the acromioclavicular (AC) joint.[1]

DCO was first described in 1936 as a condition secondary to acute shoulder trauma. Today, it is described as a sequela of trauma associated with contact sports, falls, and motor vehicle accidents.

In 1959, DCO was reported in an air-hammer operator without evidence of acute trauma. In 1982, Cahill reported on 45 male athletes with DCO, confirming repetitive microtrauma as an etiology.[2]  Of Cahill's 45 patients, 44 were weightlifters.

Anatomy

The AC joint is a diarthrodial joint. Its capsule is reinforced by the superior and inferior AC ligaments, with additional stability provided by the coracoclavicular ligaments. A fibrocartilaginous disk is present between the convex distal clavicle and the flat acromion, both of which are covered by hyaline cartilage.

Pathophysiology

A case report of hypertrophic synovial tissue that migrated across the articular cartilage and invaded subchondral bone has been published, but most specimens show disruption of articular cartilage, subchondral cyst formation, and evidence of increased osteoclastic activity.[3]

Etiology

Different theories concerning the etiology of DCO have been suggested:

  • The first theory proposed an autonomic neurovascular origin; one author noted the presence of ipsilateral anisocoria in four of eight patients
  • A theory set forth in another report proposed synovial invasion of the subchondral bone
  • Cahill, noting the presence of microfractures in subchondral bone in 50% of his cases, proposed that repetitive microtrauma caused subchondral stress fractures and remodeling [2] ; this theory is currently the most widely accepted one

Epidemiology

Although more than 100 cases have been reported in the US literature, DCO may be an underdiagnosed disorder. Its incidence has increased with the growth in popularity of weight training in the past 20 years.[4]

As more women are participating in competitive and recreational weightlifting and sports that involve overhead throwing, more women are presenting with DCO.[5] In a retrospective review of 1432 consecutive magnetic resonance imaging (MRI) shoulder reports in patients aged 13-19 years, atraumatic DCO was identified in 93 patients (6.5%), of whom 24% were female. Patients had varying symptoms; 89% of those with atraumatic DCO had pain at the AC joint or distal clavicle, and 60% had pain with participation in overhead sports.[6]

Prognosis

Although the outcome with conservative treatment is good, many patients are unable to limit their activities. These patients, as well as those in whom conservative treatment is ineffective, can expect good-to-excellent results from surgical intervention. Patients with an etiology of trauma may have an increased risk of unfavorable results. Patients can also develop symptoms in the contralateral extremity.

With regard to surgical treatment, Pensak et al investigated the difference in outcomes between open and arthroscopic resection of the distal clavicle.[7]  Specifically, arthroscopic resection had a 90% success rate, with the direct approach resulting in quicker returns to work and sport.  Poor outcomes were reproted for worker’s compensation patients and patients who had posttraumatic DCO. 

Robertson et al reviewed 49 DCO patients, of whom 32 were treated arthroscopically and 17 were treated via an open approach.[8]  At a mean follow-up of 5.3 years for the open group and 4.2 for the arthroscopic group, the arthroscopic group had a significantly lower Visual Analogue Scale (VAS) score for pain (0.61±1.02 vs 1.59±2.15). In the open group, 100% of patients reported that they would undergo the procedure again, whereas in the arthroscopic group, 97% reported that they would repeat the procedure.

 

Presentation

History

Most patients with distal clavicle osteolysis (DCO) present with pain over the distal end of the clavicle and acromioclavicular (AC) joint, which is usually described as a dull ache. Patients with an etiology of trauma report a specific event as the start of their symptoms. In patients with repetitive/overuse injuries, pain is exacerbated by athletic or work activity. In weightlifters, most symptoms occur with the bench press and related exercises.[9]

Physical Examination

On physical examination, patients have point tenderness over the affected AC joint, and cross-chest maneuvers elicit pain. Usually, the AC joint is not unstable; however, crepitation may be present. Range of motion (ROM) of the glenohumeral joint should be full.

 

DDx

Diagnostic Considerations

The differential diagnosis for distal clavicle osteolysis (DCO) must include metabolic (hyperparathyroidism), autoimmune (rheumatoid arthritis), and neoplastic (multiple myeloma) etiologies. Because DCO is usually a unilateral condition, inflammatory disease should be considered in bilateral cases.

 

Workup

Imaging Studies

Plain radiography

Obtain anteroposterior (AP) and 10-15° cephalic tilt views. Radiographs often appear normal in the early clinical course. With time, loss of subchondral bone detail in the distal clavicle, microcystic changes in the subchondral area, and widening of the acromioclavicular (AC) joint may be seen. The acromion is spared from lytic changes.

It is important to distinguish distal clavicle osteolysis (DCO) from AC joint arthritis, and outcomes after operative injury can differ substantially between the two conditions. DCO can be diagnosed when pathologic changes such as sclerosis, reactive bone formation, and subchondral cysts are restricted to the distal clavicle. The distinction between DCO and AC joint arthritis is important because patients with traumatic AC joint arthritis and degenerative arthritis tend to do worse than patients with DCO do.[10]

The presence of panarticular disease should lead to the consideration of other diagnoses (eg, inflammatory disease).

Bone scanning

If plain radiography is nondiagnostic, technetium-labeled bone scanning may help confirm the diagnosis of distal clavicle osteolysis. Increased radiotracer uptake is seen in the distal clavicle.

Magnetic resonance imaging

Some authors have recommended the use of magnetic resonance imaging (MRI) to rule out additional shoulder pathology.[11]  MRI will commonly demonstrate increased signal intensity on fat-suppressed T2-weighted and short-tau inversion recovery (STIR) images. Bone marrow edema at the distal clavicle also is a common finding and has been shown to correlate with the severity of symptoms.[10, 12]

Procedures

Because of a moderate incidence of concomitant shoulder pathology (eg, rotator cuff pathology, labral pathology, subacromial impingement, glenohumeral instability), a lidocaine injection into the AC joint may help achieve a more accurate diagnosis.[13]

 

Treatment

Approach Considerations

Patients with distal clavicle osteolysis (DCO) in whom conservative treatment fails or who refuse to limit their activities are candidates for surgical treatment.

The only contraindications noted for surgical treatment of DCO are those general to surgery. Most surgical approaches, however, can be performed without general anesthesia (for instance, with intravenous [IV] sedation and interscalene block). Patients who are at particularly high risk with surgical treatment as a consequence of medical comorbidities should consult further with their primary care physician and their institution's anesthesia department for proper preoperative risk assessment.

Medical Therapy

DCO is a self-limiting disorder that typically resolves within 1-2 years with activity modification. Conservative management consists of rest and avoidance of symptomatic activity. Nonsteroidal anti-inflammatory drugs (NSAIDs) can also help alleviate symptoms. Corticosteroid injections are often given; however, they provide little long-term relief. Although most patients respond to conservative management, symptoms often return with resumption of previous activity. (See the image below.)

Preoperative anteroposterior radiograph of male we Preoperative anteroposterior radiograph of male weightlifter with symptomatic distal clavicle osteolysis.

Surgical Therapy

The classic surgical treatment for DCO is distal clavicle resection, a reliable procedure with good-to-excellent results. Excellent results have been reported with arthroscopic distal clavicle resection.[14, 15, 16, 17, 18, 19, 20] This approach affords a more cosmetically appealing result, allows earlier return to activity, and provides a means of addressing concomitant intra-articular pathology. Arthroscopic resection can be performed through standard portals from the subacromial space, as well as via a direct superior portal (see the image below).

Left distal clavicle excision for distal clavicle Left distal clavicle excision for distal clavicle osteolysis performed with bone-cutting shaver placed in anterior portal, as viewed from direct posterior-superior portal.

A randomized, controlled trial of 38 athletes with DCO or isolated posttraumatic arthrosis of the acromioclavicular (AC) joint addressed the question of whether the direct superior approach or the indirect subacromial approach was the better procedure for arthroscopic distal clavicle resection.[21] The authors found that both procedures had successful clinical outcomes, with insignificant differences at follow-up, but that the direct approach provided faster improvement and return to activity.

The necessary extent of distal clavicle resection has been a subject of debate in the literature. Although Cahill reported excellent results with an open approach resecting 1-2 cm of bone, subsequent arthroscopic studies showed that resection of as little as 4 mm is effective.[2, 16, 18] The distal clavicle should be resected enough to prevent AC impingement through a full range of shoulder motion. Careful attention should be taken to avoid excessive bony resection and to avoid violating the posterior superior AC joint capsule, in that this can lead to horizontal instability of the AC joint.[22]

Postoperative Care

Early passive range of motion (ROM), including pendulum exercises, is important to prevent loss of shoulder motion. Because the open procedure requires partial detachment of the deltoid, active ROM is usually restricted in the early postoperative course. After arthroscopic treatment, activity is comparatively accelerated, with active ROM started within the first week.

Routine postoperative follow-up at 1-2 weeks is recommended.

Complications

Few complications from surgical treatment of DCO have been reported. One theoretical concern with aggressive distal clavicle resection is damage to the underlying neurovascular structures. A risk of infection always exists, though the risk is low in this setting. Potential development of frozen shoulder as a consequence of limited motion is a concern during the postoperative course. As noted (see Surgical Therapy), there is a risk of horizontal instability of the clavicle in the event of an overly surgical aggressive resection.