Most of the knowledge related to deltoid dysfunction stems from patients with non-neoplastic pathologies such as brachial plexus injuries, axillary nerve palsy secondary to shoulder luxation, iatrogenic nerve or muscle lesions, or after poliomyelitis [1, 2]. Loss of anterior deltoid function had been historically associated with impairment of glenohumeral function and chronic pain [1–5]. When associated with a rotator cuff tear, impairment is higher, nerve reconstruction or muscle transfer success is lower [1, 3, 4, 6].

Muscle or nerve transfer or graft for deltoid insufficiencies of any cause is associated [1, 3–6] with variable success rates. Only a few authors reported a complete range of motion with complete deltoid palsy without any reconstructive procedure [6]; they suggested that sufficient function could be obtained to allow full duty work.

Complete resection of the deltoid muscle for musculoskeletal tumors is rarely performed [7, 8]. In the tumor literature, where the loss of the deltoid muscle can be regarded as an isolated lesion with a normal rotator cuff, it is thought that partial resection of the deltoid muscle may result in normal shoulder function [8, 9], whereas complete resection compromises its function. Because of the purported limited function, consideration is often given to the addition of a latissimus dorsi, a trapezius, or a pectoralis major transfer to potentially improve the functional outcome [10, 11].

Therefore, there is continuing debate on whether a muscle transfer may improve shoulder function after complete deltoid resection. Some authors recommend muscle transfer to improve shoulder motion or strength, whereas others recommend muscle transfer solely for tissue coverage because they believe it adds little to the improvement of shoulder function. Of interest, all this literature reports on adult patients and it is unclear whether this also applies to children, who may have a greater adaptability and potential compensation for their shoulder muscle function.

We can only speculate about the reasons why there is normal shoulder function despite the complete removal of the deltoid muscle. In the normal shoulder, a combination of muscles generates a complex movement: anterior deltoid, supraspinatus, coracobrachialis, long head of biceps brachii, and clavicular portion of pectoralis major act together to provide power and movement in forward flexion. Abduction in the scapular plane is generated by the middle portion of the deltoid, supraspinatus, and a coupled force between subscapularis and infraspinatus [12, 13]. A selective bloc of the suprascapular or axillary nerve showed that the deltoid muscle provides 50% of the power for forward elevation and abduction in the plane of the scapula. Supraspinatus and infraspinatus generate almost 50% of the torque; infraspinatus acts mostly above 90 degrees of abduction. Electromyographic studies [14] showed a silent signal before 90 degrees of abduction. In the absence of deltoid and rotator cuff muscles, other muscles cannot generate enough torque to overcome gravity but act as a movement generator [12, 13]. Of interest, our patient showed excellent strength in abduction in the plane of the scapula without deltoid muscle. In addition, an MRI of his shoulder at 11-years follow-up showed normal shoulder muscles, without intraarticular degenerative changes. Although up to 20% of the patients with a complete deltoid dysfunction may achieve full (passive) range of shoulder motion [6, 15], our patient also had very good strength. Altogether, this implies that the other shoulder muscles can compensate for the loss of deltoid function after its complete removal in early childhood. Isolated deltoid resection is a rare procedure, even more in the pediatric population, and consequently it is difficult to make recommendations regarding the need for reconstruction or not based on this specific case. On the other hand, the excellent long-term follow-up of this patient with an annual physical examination and medical photography have showed that excellent function and strength remain over years without reconstruction.

To the best of our knowledge, this is the first report of complete deltoid resection without muscle transfer in a child, resulting in a full range of motion, excellent strength, and excellent function of the shoulder at long-term follow-up. The remaining shoulder muscles have the potential to compensate for the loss of deltoid function in very young children thereby avoiding the need for complex procedures like pedicled latissimus muscle flap or trapezius transfer unless needed for soft tissue coverage.