FRIDAY, April 29 (HealthDay News) -- Helical cutting of the Achilles tendon may allow a greater increase in tendon length than z-plasty, along with reliable tendon continuity and improved resistance to tensile load, according to an animal study published in the April 20 issue of The Journal of Bone & Joint Surgery.
Mazda Farshad, M.D., from the University Hospital Balgrist in Zurich, Switzerland, and colleagues investigated a new approach to increase Achilles tendon length while preserving tendon continuity in 35 study and five reference Achilles tendons harvested from freshly slaughtered calves. They cut 30 of the tendons at helical angles of 60, 45, and 30 degrees, along a helical axis, and left them either unsutured or sutured with mattress stitches along the cut lines. They lengthened five tendons by conventional z-plasty and left five tendons untreated for reference. They quantitatively assessed failure behavior in uniaxial tension.
The investigators found that tendon length and tensile strength increased by an average 172 percent of the original length and 70 N, respectively, by z-plasty. Helical cutting at a 30-degree angle resulted in maximum average length increase to 279 percent of original with a corresponding average load to failure of 30 N. Helical cutting at a 60-degree angle resulted in average length increase of 212 percent of original associated with an average load to failure of 222 N.
"Compared with the existing approaches to tendon-lengthening, helical cutting of tendons offers the potential for increased tendon length and better biomechanical performance. This in vitro study lays a biomechanical foundation for a subsequent clinical investigation in patients," the authors write.