This case reports findings in an 18-year-old female who presented with motion aberration (kinesiopathology) of the left shoulder consisting of dysrhythmia of the glenohumeral joint and early lateral rotation of the scapula. To ascertain what is known about this type of condition a literature search was conducted via the database PubMed using the keywords "nontraumatic glenohumeral", "scapulohumeral", "subscapularis", "motor engram", and "glenohumeral instability", with the limits: All Adult (19+ years), English, Clinical Trial, Meta-Analysis, Practice Guideline, Randomised Controlled Trial, Review, Case Reports, Humans, Core Clinical Journals. This search did not return any case studies or clinical trials relating to this type of shoulder dysfunction, but several articles discussing shoulder kinematics and rehabilitation were located.

Glenohumeral joint stability is primarily dependant on muscle, hence it is often referred to as a muscular joint [1]. It is the most mobile joint in the human body, but the sacrifice for this mobility is stability, with glenohumeral instability (and resulting dysfunction) being a common finding [2]. While this anatomical arrangement predisposes the shoulder to traumatic changes, it is important to remember that non-traumatic dysfunction can also occur. Some cases relating to muscular imbalance of the glenohumeral and scapulothoracic joints [3] and faulty motor patterns (or joint region coordination) [4] have been reported. However none of these presented with findings similar to the case being reported. It is worth considering similar cases since many patients who present with shoulder pain continue to report pain 6–12 months later in spite of treatment [5].

Matias, et al [6] found that the faulty scapular kinematics of shoulder instability are perhaps related to suboptimal muscular activity. For example Bak [3], Blaimont, et al [7], Kuechle, et al [8], and Decker [9] all highlight the role the subscapularis plays in shoulder instability. Other important stabilizer functions of the shoulder region have been identified, including normal facilitation of the rotator cuff muscles and normal tone of the pectoralis major and deltoid muscles [10]. Labriola [10] states that if the pectoralis major and deltoid muscles are hypertonic, they also may promote glenohumeral instability.

Current trends in shoulder rehabilitation are numerous, varying from scapula-based [11] to kinetic chain [12] to more neuromotor-based [13] processes. Concurrently, shoulder rehabilitation protocols have been directed towards specific shoulder complex conditions, to include post-surgical [14], rotator cuff injury [15], and impingement [16]. It is claimed that inappropriate clinical attention to specific stabilizers, such as those that control the scapula, may result in further altered mechanics of the shoulder complex [17].

Stark [18] proposed a general physical rehabilitation pyramid guide as a theoretical construct. The base of this pyramid (Tier 1) is formed by a focus on cognitive facilitation, static proprioception (posture), and faulty mechanics correction. If motor coordination is learned and other aberrant conditions are "corrected", the patient is advised to progress through ascending levels of cardiovascular conditioning and dynamic proprioception training (Tier 2), stabiliser conditioning (Tier 3), mobiliser conditioning (Tier 4), and ADL (activities of daily living) conditioning (Tier 5).

This study reports the history, clinical examination, imaging and the challenging choice of management of a patient with an unusual shoulder movement dysfunction.

This patient demonstrated unusual kinesiopathology of the left shoulder (in abduction) consisting of dysrhythmia of the glenohumeral joint and early lateral rotation of the scapula. It is important in cases such as these to consider the possible anatomical and functional causes of such a disturbed motion pattern.

We chose to use an untested intervention to assist with examination and treatment. We specifically instructed the patient to cognitively (consciously) co-contract the shoulder girdle while performing an active range of motion assessment. As it transpired the patient was able to cognitively correct the dysrhythmia by co-contracting the shoulder. It is worth considering that in such patients there may be a component of neuromuscular dysfunction causing the multiple subluxation patterns.

The improvement during examination with co-contraction led the practitioners to suggest a rehabilitation protocol that was based on the patient's cognitive ability to co-contract during activities of daily living and then subsequently to progress on to stabilizer motor control exercises and strengthening.

As appreciated in the fluoroscopy video, there is apparent premature scapular movement and an obvious inability to stabilize the scapula and glenohumeral (GH) joint throughout the abduction movement. Scapular dyskinesia is common, especially with impingement disorders [22]. In order for the shoulder complex to function smoothly, the scapula must have an adequate amount of stability [17] as well as the GH joint [10]. This stability may initially require cognitive facilitation of the scapula stabilizers and the glenohumeral joint stabilizers.

Particular attention to the proximal-to-distal kinetic chain [23] may further benefit the order of stability training needed to establish an optimum motor pattern. As the patient is attempting to re-train the necessary muscle function he/she may incorporate co-contraction of the region. Co-contraction has been appreciated as a mechanism to potentially enhance joint region efficiency during moments of increased accuracy demand [13, 24]. Co-contraction is a simple non-invasive manoeuvre that, as demonstrated in this case, can be implemented as an assessment element just as it can a rehabilitation element.

Although this patient's condition improved no conclusion is drawn from it. However, the assessment and rehabilitation method was implemented in a logical sequence for this case and could provide the basis of a hypothesis for testing. The background information for this clinical presentation was limited to one search engine. Further resources should be utilized if a case series is considered.

The General Functional Assessment Pyramid and the General Physical Rehabilitation Pyramid used in this case report has not been subjected to research testing. The pyramids contain many parts. It may be that some parts are effective while others are not, or indeed that the pyramids are not effective at all.

This paper presented an unusual case of aberrant shoulder movement that highlights the need for careful examination and thought regarding the anatomical structures and neuro-motor patterns that may be involved or compromised. It also emphasised the use of co-contraction during examination in an attempt to immediately improve a dysrhythmia. While there are numerous treatments proposed in the literature for shoulder dysfunction, few have been held to the scrutiny of a trial [25]. We suggest that further research take place with properly conducted trials on groups of similar patients.