gms | German Medical Science

Objectives/Interrogation: The complete lesions of the flexor tendons are complex problems in hand surgery. In cases of concomitant lesions of the flexor tendons in zone 2, the exclusive tenorrhaphy of the flexor digitorum profundus (FDP) or the tenorrhaphy of the FDP associated with one of the two slips of flexor digitorum superficialis (FDS) is the intervention that most limits the development of a flexor-extensor deficit in the post-operative period. Inside digital channel, FDS is divided into two slips, ulnar and radial, before insertion from a fundamental structure for stability and dynamic function: Camper's Chiasma. The purpose was to establish correlation between anatomical structure andflexor tendon function at Camper's chiasm, and describe relationships between chiasma and surrounding structures (phalanges, pulleys, skin folds and vincula). This can guide for the best operative option. Another objective is to provide a rational basis for choice the FDS slip to be sacrificed in palliative procedures.

Methods: 36 fingers in 9 hands were studied from fresh corpse. A broken-line incision was made on the volar skin of the fingers. The skin flaps and subcutaneous tissue were lateralized and pulleys were incised exposing flexor tendons. We have observed the anatomy of Camper's chiasma with its vascularization and we have measured the distances between chiasma, articular structures and pulleys.

Results and Conclusions: In all examined fingers we observed a certain degree of asymmetry in the representation and direction of the two slips of the FDS which constitute the chiasm. In most cases at level of II and III finger the ulnar band is constituted by a greater quantity of fibers and some of these decusses in a unidirectional manner at the level of the Camper's chiasma reaching and reinforcing the radial insertion. Inverse behavior was often observed at the IV and V finger of the hands examined. This asymmetry seems to be correlated with the vascular supply by vincula longa. Contrary to literature, we have observed a constant asymmetry of Camper's chiasm tendon fibers. The direction of the tendon structures and the force vectors that are activated during the flexion could be an explanation for this asymmetry for blood supply at the level of one of the two FDS slips. This could guide the surgeon towards the choice to repair and protect the most vascularized slip in case of post-traumatic reconstruction or elective transposition surgery, with advantages for good healing.