title: Biomechanical comparison of Krackow locking stitch versus nonlocking loop stitch with varying number of throws.
abstract: BACKGROUND
  Common suture configuration techniques used for ligament and tendon grafts and repair are the Krackow locking stitch and a nonlocking loop stitch, such as a whipstitch. Clinically, the preferences of orthopaedic surgeons vary.
  
  
  OBJECTIVE
  The Krackow locking stitch and the nonlocking whipstitch, with varying suture loops, produce different biomechanical and physical effects on the tendon end.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  A total of 52 fresh-frozen porcine flexor digitorum tendons were used and assigned into 10 groups. Two stitch configurations (Krackow stitch [K] and whipstitch [W]) with varying number of loops (2 throws, n = 6; 4 throws, n = 5; 6 throws, n = 5; 8 throws, n = 5; 10 throws, n = 5) were tested. No. 2 FiberWire was used. Each sample was preloaded to 5 N and then cyclically loaded for 200 cycles to 200 N at 1 Hz, and then the tendon-suture construct was analyzed for gap formation, tendon elongation, and tendon end width. Next, each tendon was loaded to failure, and ultimate strength and mode of failure were recorded. Data were evaluated with 2-way analysis of variance.
  
  
  RESULTS
  For gap formation, the Krackow stitch produced less gap compared with the whipstitch (15.2 ± 4.0 mm [K] vs 18.9 ± 6.8 mm [W]; P = .012). Gap formation was larger when the number of loops increased from 2 to ≥6 (P = .015). For elongation, the Krackow technique increased the tendon length after cyclic loading. In contrast, the whipstitch was noted to shorten the length of the tendon (1.17 ± 0.97 mm [K] vs -0.14 ± 1.13 mm [W]; P < .001). For tendon end width, the Krackow better preserved the transverse width (-0.64 ± 0.81 mm [K] vs -1.39 ± 0.64 mm [W]; P = .001). Both stitch types had similar ultimate strength (322.1 ± 20.3 N [K] vs 319.7 ± 20.4 N [W]; P = .676) and modes of failure (all by suture breakage; therefore, no statistical calculation was performed). There was no statistical difference in tendon elongation, width, failure load, or mode regardless of the number of throws.
  
  
  CONCLUSIONS
  Given the finding that the Krackow suture had less gap formation and better preservation of tendon architecture (length and width) compared with the whipstitch, coupled with the finding that ultimate strength is similar with both types of sutures, the Krackow stitch is recommended for tendon reconstruction when these parameters are important.
authors.affiliation: Department of Orthopaedic Surgery, Loma Linda University, Loma Linda, California, USA.
authors.forename: Joseph Minsoo
authors.initials: JM
authors.lastname: Hahn
authors.affiliation: Department of Orthopaedic Surgery, Loma Linda University, Loma Linda, California, USA.
authors.forename: Serkan
authors.initials: S
authors.lastname: Inceoğlu
authors.affiliation: Department of Orthopaedic Surgery, Loma Linda University, Loma Linda, California, USA dwongworawat@llu.edu.
authors.forename: Montri Daniel
authors.initials: MD
authors.lastname: Wongworawat
mesh_terms: D000818:Animals; D008422:Materials Testing; D023421:Models, Animal; D013536:Suture Techniques; D013552:Swine; D013710:Tendons / Q000601:surgery*; D013718:Tensile Strength
keywords: Achilles tendon repair; Krackow stitch; biomechanical testing; soft tissue fixation; suture slippage; whipstitch