Evaluation of the Efficacy of Suprascapular Nerve Block in Adhesive Capsulitis: a Randomized Controlled Superiority Trial

The glenohumeral joint is a highly mobile joint involving abduction, anterior elevation, external rotation and internal rotation. It is composed of a capsule innervated by the suprascapular nerve. Retractile capsulitis is a frequent pathology, affecting 2 to 5% of the general population, and associating both pain and stiffening of the joint, leading to functional discomfort, particularly in abduction and external rotation movements. It is due to capsular retraction of the shoulder joint, which may be idiopathic or secondary to traumatic or neurological etiology, or associated with diabetes. In the majority of cases, this pathology leads to recovery, but the time to total recovery is variable, ranging from six months to one year. Some studies have even shown the persistence of symptoms, with an average follow-up time of four years in some patients. The majority of patients are off work due to the functional discomfort associated with shoulder stiffness.

Therapeutic management is currently poorly codified. Physiotherapy using active mobilization maneuvers has been shown to improve joint amplitudes, and is used as a first-line treatment. In the event of persistent symptoms, cortisone infiltration has been evaluated using a variety of protocols, including sub-acromial and intra-articular infiltration, as well as arthro-distension, which consists of dilating the capsule under radiological control using 1 intra-articular injection of xylocaine, corticoids and contrast medium. In France, arthrodistension has become the reference technique, as it is more effective than intra-articular infiltration of cortisone derivatives. In fact, several trials and meta-analyses have demonstrated short-term superiority in improving the pain associated with capsulitis and, above all, better progress in terms of joint amplitude, as assessed in particular by Constant's algo-functional scores.

If adhesive capsulitis persists despite these therapies, arthroscopic surgery is sometimes performed.

The suprascapular nerve is a mixed nerve whose sensitive component is the main sensitive branch innervating the shoulder. An anaesthetic block of this nerve provides a punctual reduction in painful sensations in the shoulder, enabling less painful arthrodistension and pain-free physiotherapy sessions for faster joint amplitude work. Several studies have compared suprascapular nerve block versus intra-articular infiltration in this condition, with conflicting results which nevertheless show a trend towards improved joint amplitudes and earlier onset of pain in the anesthetic block group. However, no study has compared suprascapular nerve block with arthrodistension, which remains the standard treatment in Europe. Moreover, no study has investigated the superiority of adding this therapy to arthrodistension. Our hypothesis is that suprascapular nerve block combined with arthrodistension may accelerate healing.

The main benefit expected for the patient is the shortening of the time to improvement (recovery of joint amplitudes, functional improvement and improvement in quality of life).