Pain referral from the sternoclavicular joint: a study in normal volunteers

Objective. The sternoclavicular joint (SCJ) is commonly affected by rheumatological conditions. Case reports suggest that it may refer pain to distant areas, potentially leading to delays in diagnosis and inappropriately targeted investigations. Therefore, we studied the patterns of pain referral from the SCJ of nine healthy volunteers. Methods. Hypertonic saline was injected into the SCJ of nine normal volunteers and the location of any resulting pain was noted, as was the effect of resisted shoulder abduction and flexion. Composite pain maps were then constructed from individual pain diagrams. Results. An unpleasant, deep aching pain was produced locally in eight subjects and referred to distant sites in all subjects. Tests of shoulder movement had varied and inconstant effects. Conclusions. We demonstrated that the SCJ is capable of referring pain to areas distant from the joint. Knowledge of these referral patterns will enable the SCJ to be considered in patients with pain in these areas. Pain is one of the cardinal symptoms leading to presentation of rheumatic diseases. It is axiomatic that a sound knowledge of the significance of pain in any given anatomical area will facilitate appropriate investigation and treatment. In the proximal upper limb and the lower neck this is particularly pertinent as several structures have the potential to refer pain to the region of the shoulder cowl and lower neck. These include the cervical zygapophyseal joints and intervertebral discs, the acromioclavicular joint and the subacromial space, as well as non-musculoskeletal structures such as the heart and cervical nerve roots. Knowledge of the patterns of pain that may originate from these structures may lead the clinician to consider appropriate diagnostic possibilities for a particular presentation. Conversely, unlikely possibilities could be discounted. The patterns of pain referral from the cervical nerve roots w1x and cervical zygapophyseal joints w2‐ 4x have been studied, as has the pattern from the acromioclavicular joint and subacromial space w5x. However, to-date there have been no similar experimental data on the patterns of pain that may arise from the sternoclavicular joint (SCJ). The SCJ is a diarthrodial joint, divided into medial and lateral compartments by an intra-articular, fibrocartilaginous disc and is the only synovial articulation between the upper limb and the axial skeleton. As a source of referred pain, the SCJ has been implicated in the differential diagnosis of shoulder, subscapular, neck, arm and chest wall pain in case reports and review articles, w 6‐ 8x. Interest in the SCJ is not simply academic. It is affected by common rheumatological pathologies including osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, sternoclavicular hyperostosis, infection, hyperparathyroidism, traumatic dislocations and metastases. The SCJ is not seen well on conventional radiographs and is not always included in the rheumatological examination. Therefore, SCJ pathology may be missed or not considered if it has distant, but unrecognized, patterns of referral. We therefore performed a study to determine whether irritation of the SCJ in normal volunteers produced characteristic patterns of pain and to map these patterns. The results demonstrated a surprisingly diverse set of referral patterns, with important clinical implications in the assessment of patients with pain in the neck, arm and shoulder.