title: Biomechanical characteristics of the horizontal mattress stitch: implication for double-row and suture-bridge rotator cuff repair.
abstract: BACKGROUND
  We investigated the effects of bite-size horizontal mattress stitch (distance between the limbs passed through the tendon) on the biomechanical properties of the repaired tendon.
  
  
  METHODS
  We anchored 20 bovine Achilles tendons to bone using no. 2 high-strength suture and 5-mm titanium suture anchors in a mattress-suture technique. Tendons were allocated randomly into two groups of ten each to receive stitches with a 4- or 10-mm bite. Specimens underwent cyclic loading from 5 to 30 N at 1 mm/s for 30 cycles, followed by tensile testing to failure. Gap formation, tendon strain, hysteresis, stiffness, yield load, ultimate load, energy to yield load, and energy to ultimate load were compared between groups using unpaired t tests.
  
  
  RESULTS
  The 4-mm group had less (p < 0.05) gap formation and less (p < 0.05) longitudinal strain than did the 10-mm group. Ultimate load (293.6 vs. 148.9 N) and energy to ultimate load (2,563 vs. 1,472 N-mm) were greater (p < 0.001) for the 10-mm group than the 4-mm group. All tendons repaired with 4-mm suturing failed at the suture-tendon interface, with sutures pulling through the tendon, whereas the suture itself failed before the tendon did in seven of the ten specimens in the 10-mm group.
  
  
  CONCLUSIONS
  Whereas a 4-mm bite fixed the tendon more tightly but at the cost of decreased ultimate strength, a 10-mm bite conveyed greater ultimate strength but with increased gap and strain. These results suggest that for the conventional double-row repair, small mattress stitches provide a tighter repair, whereas large stitches are beneficial to prevent sutures from pulling through the tendon after surgery. For suture-bridge rotator cuff repair, large stitches are beneficial because the repaired tendon has a higher strength, and the slightly mobile medial knot can be tightened by lateral fixation.
authors: Orthopaedic Biomechanics Laboratory, VA Healthcare System, Long Beach, CA, USA; University of California, Irvine, CA, USA.
authors: Mallika
authors: M
authors: Tamboli
authors: Orthopaedic Biomechanics Laboratory, VA Healthcare System, Long Beach, CA, USA; University of California, Irvine, CA, USA.
authors: James
authors: J
authors: Hwang
authors: Orthopaedic Biomechanics Laboratory, VA Healthcare System, Long Beach, CA, USA; University of California, Irvine, CA, USA.
authors: Michelle H
authors: MH
authors: McGarry
authors: Orthopaedic Biomechanics Laboratory, VA Healthcare System, Long Beach, CA, USA; University of California, Irvine, CA, USA.
authors: Yangmi
authors: Y
authors: Kang
authors: Orthopaedic Biomechanics Laboratory, VA Healthcare System, Long Beach, CA, USA; University of California, Irvine, CA, USA.
authors: Thay Q
authors: TQ
authors: Lee
authors: Orthopaedic Biomechanics Laboratory, VA Healthcare System, Long Beach, CA, USA; University of California, Irvine, CA, USA; Department of Orthopedic Surgery, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki, Osaka 569-8686, Japan. Electronic address: tmihata@yahoo.co.jp.
authors: Teruhisa
authors: T
authors: Mihata
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D004195:Disease Models, Animal; D017006:Rotator Cuff / Q000503:physiopathology / Q000601:surgery*; D000070636:Rotator Cuff Injuries; D013536:Suture Techniques; D013537:Sutures; D013708:Tendon Injuries / Q000503:physiopathology / Q000601:surgery*; D013718:Tensile Strength