The location of the inferior angle of the scapula in relation to the spine in the upright position: a systematic review of the literature and meta-analysis

Practitioners in several of the health care professions use anatomical landmarks to identify spinal levels, both in order to enhance diagnostic accuracy and to specifically target the site of intervention. Authoritative sources usually state the upright inferior scapular angle (IAS) aligns with the spinous process (SP) of T7, but some specify the T7-8 interspace or the T8 SP. The primary goals of this study were to systematically review the relevant literature; and conduct a meta-analysis of the pooled data from retrieved studies to increase their statistical power. Electronic searching retrieved primary studies relating the IAS to a spinal level, as determined by an imaging reference standard, using combinations of these search terms: scapula, location, landmark, spinous process, thoracic vertebrae, vertebral level, palpation, and spine. Only primary studies were included; review articles and reliability studies related to scapular position but lacking spinal correlations were excluded. Eight-hundred and eighty (880) articles of interest were identified, 43 abstracts were read, 22 full text articles were inspected, and 5 survived the final cut. Each article (with one exception) was rated for quality using the QUADAS instrument. Pooling data from 5 studies resulted in normal distribution in which the upright IAS on average aligns closely with the T8 SP, range T4-T11. Since on average the IAS most closely identifies the T8 SP in the upright position, it is very likely that health professionals, both manual therapists and others, who have been diagnosing and treating patients based on the IAS = T7 SP rule (the conventional wisdom), have not been as segmentally accurate as they may have supposed. They either addressed non-intended levels, or made numeration errors in their charting. There is evidence that using the IAS is less preferred than using the vertebra prominens, and may be less preferred than using the iliac crest for identifying spinal levels Manual therapists, acupuncturists, anesthesiologists, nurses, and surgeons should reconsider their procedures for identifying spinal sites in light of this modified information. Inaccurate landmark benchmark rules will add to patient variation and examiner errors in producing spine care targeting errors, and confound research on the importance of specificity in treating spinal levels. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12998-014-0050-7) contains supplementary material, which is available to authorized users.