Ispitivanje biomehaničkih karakteristika modificiranih šavova fleksornih tetiva na animalnom modelu [Biomechanical trial of modified flexor tendon sutures - in vitro study]

Background Intrasynovial flexor tendon repairs, because of historically unsatisfactory results (referred as “no man’s land”), belong to the most studied in hand surgery. There are numerous modifications and variations of those repairs. Clinicians’ preference in Croatia is still modified Kessler’s suture with early passive mobilization protocol referred as Kleinert’s protocol. Proven benefits of early active mobilization have inducted new criteria of “perfect suture” especially addressed to ultimate force. In this study we have examined different modifications and variations of modified Kessler’s suture, which could fulfill new criteria. Methods Ninety-three fresh pig trotters were stored at –20°C and each was thawed to room temperature just before tendons dissection, transsection, suture placement, and testing using dynamometer with constant rate of extension. The total of 93 extensor digiti quarti proprius tendons were repaired under 3.5 magnification and divided into three main groups of 10 specimens: modified Kessler suture, double modified Kessler suture and intact tendons as a control group, and seven additional groups of 10-12 specimens with further variations in type of thread (braided or monofilament), location and number of the knots (interlocked, doubled or out sided knot), and type of peripheral suture (simple "over and over" or cross-stitched). Results The ultimate (maximum) force, maximum elongation, work and time have pointed out significant difference among three main groups but comparation of the seven additional variations did not vary significantly in elongation, work and time except in ultimate force. Conclusions The ultimate force for the chosen basic modification of the double modified Kessler (DMK) was significantly higher then standard modified Kessler. The version of DMK with crossed peripheral suture was the strongest one among all tested variations. This version presumable could achieve, concerning range of force, early active mobilization opposite of the simple “over and over” peripheral stitch. The lowest strength manifested variations with two knots between tendon ends. The variation with interlocked and out sided knots or monofilament tread were not statistically significant regarding ultimate force. The frequency of suture failure of basic modification of DMK (suture pull out or tendon and/or suture rupture) was equal respecting braided or monofilament thread.