As new advances in medical technology lead to treatments for injuries and diseases, one concept that has emerged is the importance of genetic predisposition to health, sickness, and functional recovery after trauma. Indeed, as the future of medicine will most likely concentrate on health as opposed to health care, understanding the genetic predisposition to medical conditions will become paramount. In the February 2016 issue of JBJS Reviews, Prodromidis and Charalambous focus on the role of genetics in the development and treatment of frozen shoulder. This article represents a careful analysis of the relationship between genetics and disease.
Frozen shoulder, or adhesive capsulitis, is a common condition that leads to functional loss and impairment of activities of daily living. However, despite the prevalence of this condition, its pathogenesis is not fully understood. Prodromidis and Charalambous performed a systematic review and meta-analysis in order to assess the evidence that suggests a genetic link to frozen shoulder.
The investigators performed a literature search of MEDLINE, EMBASE, and CINAHL using relevant keywords and found an initial 5506 studies. After further screening, seven studies were analyzed. The results were fascinating. One study, involving 1828 twin pairs, showed an 11.6% prevalence and demonstrated a heritability of 42% for frozen shoulder after adjusting for age. In a second study, involving 273 patients, 20% of patients with frozen shoulder had a positive family history involving a first-degree relative. A third study, involving 87 patients, showed that 29% of patients with frozen shoulder had a first-degree relative with this condition.
Two further studies evaluated racial predilection. One of these studies (50 patients) showed a substantially higher number of white patients with frozen shoulder than black patients with the condition. The other study (87 patients) showed that being born or having parents or grandparents who were born in the British Isles were risk factors for this condition.
Finally, four immunological studies investigated HLA-B27 as a risk factor for frozen shoulder. A meta-analysis of two of these studies with clearly defined controls showed higher rates of HLA-B27 positivity in patients with this condition as compared with controls (p < 0.001).
Thomas Einhorn, Editor