Understanding frozen shoulder in the hemiparetic arm after stroke

Frozen shoulder is more common in the weakened hemiparetic shoulder post stroke than in the general population. Increasing age, micro-vascular co-morbidities and the presence of subluxation make the soft tissue of the hemiparetic shoulder more susceptible to injury and inflammation. Inflammation can trigger fibrosis of the shoulder ligamentous capsule due to a disruption of joint homeostasis. It is this fibrosis that results in the common presenting features of frozen shoulder, namely restriction of passive shoulder external rotation, abduction and internal rotation. Spasticity of shoulder adductors and internal rotators is also common in hemiparesis and is hard to differentiate from frozen shoulder. Diagnostic lateral pectoralis nerve blocks (DNBs) may help to differentiate between the two. However, several muscles often contribute to shoulder adductor and internal rotator spasticity, so there is a risk of false positives with DNBs. Frozen shoulder is still largely a clinical diagnosis after assessment and exclusion of other possibilities. In cases of Frozen shoulder, daily movements of the shoulder joint within tolerable pain limits can help to restore joint homeostasis and lead to reduced pain. Steroid injection (either alone or as part of a hydrodilatation injection) when inflammation is present can also reduce pain and improve range when used in combination with physiotherapy.