Practice Essentials
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, 2]
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. [3] Of Cahill's 45 patients, 44 were weightlifters.
Most patients with DCO respond to conservative management, though symptoms often return with resumption of previous activity. Patients in whom conservative treatment fails or who refuse to limit their activities are candidates for surgical treatment (distal clavicle resection). The only contraindications noted for surgical treatment of DCO are those general to surgery.
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. [4]
Etiology
Different theories concerning the etiology of DCO have been suggested:
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The first theory proposed an autonomic neurovascular origin; one author noted the presence of ipsilateral anisocoria in four of eight patients
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A theory set forth in another report proposed synovial invasion of the subchondral bone
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Cahill, noting the presence of microfractures in subchondral bone in 50% of his cases, proposed that repetitive microtrauma caused subchondral stress fractures and remodeling [3] ; 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 few decades. [5]
As more women are participating in competitive and recreational weightlifting and sports that involve overhead throwing, more women are presenting with DCO. [6] 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. [7]
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. [8] Specifically, arthroscopic resection had a 90% success rate, with the direct approach resulting in quicker returns to work and sport. Poor outcomes were reported 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. [9] The mean follow-up was 5.3 years for the open group and 4.2 years 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.
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Anteroposterior radiograph of 26-year-old male weightlifter with symptomatic distal clavicle osteolysis that responded to conservative measures.
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Left distal clavicle excision for distal clavicle osteolysis performed with bone-cutting shaver placed in anterior portal, as viewed from direct posterior-superior portal.
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Preoperative anteroposterior radiograph of male weightlifter with symptomatic distal clavicle osteolysis.
