Standard 4-strand repair of Achilles tendon tears is effective, but additional strength may be desirable in patients who are compromised or those with reruptures. Use of a xenograft scaffold has not been investigated biomechanically in Achilles tendon repair. This study compared stiffness, gap formation, and ultimate load to failure with Krackow repair vs Krackow repair augmented with xenograft scaffold in 6 matched pairs of fresh-frozen human lower extremities. The Achilles tendon was transected 4 cm above the calcaneal insertion. Specimens were randomized to receive standard Krackow repair or Krackow repair augmented with a porcine xenograft scaffold. The graft was wrapped around the repaired tendon, sutured to itself with 2-0 FiberWire ( Arthrex, Naples, Florida), and attached to the tendon distally and proximally and then medially and laterally. Specimens were loaded for 200 cycles between 5 and 30 N. Load to 5-mm gapping and load to ultimate failure were measured. Xenograft scaffold augmentation of standard Krakow Achilles tendon repair was significantly stronger and stiffer than standard Krackow repair in a biomechanical model immediately after repair ( 39.0 +/- 8.8 vs 24.4 +/- 4.6 N/mm; P=.01). The augmented repair group had significantly higher load to ultimate failure than did the Krackow group ( 862.7 +/- 174.0 vs 479.5 +/- 65.5 N; P <.01). Biological factors remain to be investigated, but this augmentation method could provide additional strength in patients who are compromised or those with reruptures.
