title: In vivo blood flow after rotator cuff reconstruction in a sheep model: comparison of single versus double row.
abstract: OBJECTIVE
  Arthroscopic double-row (DR) suture anchor repair of rotator cuff tears has been shown to be superior to most single-row (SR) techniques with regard to footprint reconstruction, load to failure and tendon-to-bone contact pressures. The hypothesis of this study was that the greater contact pressures of DR techniques would compromise blood flow to a higher degree than SR repair. The aim of this experimental study was to evaluate the effect of a DR and a SR technique on tendon blood flow in a sheep model.
  
  
  METHODS
  Eighteen sheep underwent detachment and immediate repair of the infraspinatus tendon using either a Mason-Allen or a suture-bridge technique. Tendon blood flow was measured using laser Doppler flowmetry before detachment, immediately after repair and 12 weeks thereafter. Six regions of interest were measured, three over the lateral and three over the medial aspect of the footprint.
  
  
  RESULTS
  Immediately after repair, tendon blood flow decreased significantly in both repair groups (P = 0.004). In the SR group, blood flow decreased by 100.1 arbitrary units (AU) (83.6 %) after repair, in the DR by 81.4 AU (90.5 %). Subgroup analysis showed blood flow over the lateral aspect of the footprint decreased by 126.3 AU (92.2 %) in the SR and 84.4 AU (90.9 %) in the DR group, whereas over the medial aspect, it decreased by 73.9 AU (72.0 %) in the SR and 78.5 AU (90.1 %) in the DR group. None of the differences between the groups were significant. At 12 weeks, measured blood flow in the DR group had increased to 90.1 AU (100.2 %) compared to the native tendons and was at 72.5 AU (60.5 %) for the SR group. Again, the difference between SR and DR group was not statistically significant (n.s.). Assessment for retears showed that 4 of 8 tendons (50 %) in the DR group and 3 of 9 tendons (33.3 %) in the SR group had to be classified as re-ruptures.
  
  
  CONCLUSIONS
  Suture anchor repair leads to an intraoperative decrease in tendon blood flow regardless of the repair technique. A significant difference between SR and DR repair was not found. These findings indicate that tendon blood flow should not be a factor to determine the use of either repair technique over the other.
authors: Department of Orthopedics and Tumor Orthopedics, University Hospital Muenster, Albert-Schweitzer-Campus 1, 48149, Muenster, Germany, dennis.liem@ukmuenster.de.
authors: Dennis
authors: D
authors: Liem
authors: Nicolas J
authors: NJ
authors: Dedy
authors: Gregor
authors: G
authors: Hauschild
authors: Georg
authors: G
authors: Gosheger
authors: Shirin
authors: S
authors: Meier
authors: Maurice
authors: M
authors: Balke
authors: Hans-Ulrich
authors: HU
authors: Spiegel
authors: Bjoern
authors: B
authors: Marquardt
mesh_terms: D000818:Animals; D001182:Arthroscopy; D017078:Laser-Doppler Flowmetry; D023421:Models, Animal; D017006:Rotator Cuff / Q000098:blood supply* / Q000601:surgery*; D012756:Sheep; D053441:Suture Anchors; D013536:Suture Techniques
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