The anatomy and prevalence of the juncturae tendinum in the hands. A systematic review and meta-analysis

The movement of the fingers of the hand is thought to be limited in extension due in part to the presence of the juncturae tendinum (JT) in the dorsal webspaces. Clinically, these structures may help surgeons in identifying the extensor slips of the extensor digitorum communis (edc) and constitute an additional resource for tendon repair. These connections are highly variable in relation to their frequency and shape. Based on von Schroeder’s classification, an evidence synthesis of those structures was performed; nineteen cadaveric studies were located with a total of 2060 hands. Using meta-analytical methods, the pooled prevalence values were computed for each webspace and each type of JT; the JT type 1 (JT-1) and 3 (JT -3) were by far the most common in the 2nd and 4th webspaces, respectively. In the 3rd webspace, the JT type 2 (JT-2) had the highest prevalence value, followed by JT-3 and JT-1. The pooled means of JT size revealed that JT-3 was significantly longer and thicker than JT-1 and JT-2, while JT-1 was significantly wider than JT-2 and JT-3. Ancestry-based prevalence values showed that Middle Eastern populations had the lowest overall JT prevalence values, and Indian and Turkish ancestries had the highest values. Side-based prevalence values demonstrate significance only for the JT-3y type in the 4th webspace, where it was twice more frequent on the left side. While JT-3 was not infrequent between edc to the ring finger and extensor digiti minimi (16.5%), it occurred 13 times more when edc to the little finger was absent. This anatomical meta-analysis is likely to generate more accurate prevalence and mean size values of the juncturae tendinum in human hands.