title: Three-dimensional evaluation of cyclic displacement in single-row and double-row rotator cuff reconstructions under static external rotation.
abstract: BACKGROUND
  The double-row suture bridge repair was recently introduced and has demonstrated superior biomechanical results and higher yield load compared with the traditional double-row technique. It therefore seemed reasonable to compare this second generation of double-row constructs to the modified single-row double mattress reconstruction.
  
  
  OBJECTIVE
  The repair technique, initial tear size, and tendon subregion will have a significant effect on 3-dimensional (3D) cyclic displacement under additional static external rotation of a modified single-row compared with a double-row rotator cuff repair.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Rotator cuff tears (small to medium: 25 mm; medium to large: 35 mm) were created in 24 human cadaveric shoulders. Rotator cuff repairs were performed as modified single-row or double-row repairs, and cyclic loading (10-60 N, 10-100 N) was applied under 20° of external rotation. Radiostereometric analysis was used to calculate cyclic displacement in the anteroposterior (x), craniocaudal (y), and mediolateral (z) planes with a focus on the repair constructs and the initial tear size. Moreover, differences in cyclic displacement of the anterior compared with the posterior tendon subregions were calculated.
  
  
  RESULTS
  Significantly lower cyclic displacement was seen in small to medium tears for the single-row compared with double-row repair at 60 and 100 N in the x plane (P = .001) and y plane (P = .001). The results were similar in medium to large tears at 100 N in the x plane (P = .004). Comparison of 25-mm versus 35-mm tears did not show any statistically significant differences for the single-row repairs. In the double-row repairs, lower gap formation was found for the 35-mm tears (P ≤ .05). Comparison of the anterior versus posterior tendon subregions revealed a trend toward higher anterior gap formation, although this was statistically not significant.
  
  
  CONCLUSIONS
  The tested single-row reconstruction achieved superior results in 3D cyclic displacement to the tested double-row repair. Extension of the initial rupture size did not have a negative effect on the biomechanical results of the tested constructs.
  
  
  CONCLUSIONS
  Single-row repairs with modified suture configurations provide comparable biomechanical strength to double-row repairs. Furthermore, as increased gap formation in the early postoperative period might lead to failure of the construct, a strong anterior fixation and restricted external rotation protocol might be considered in rotator cuff repairs to avoid this problem.
authors.affiliation: Department of Orthopedic Surgery, Saarland University, Homburg, Germany. olaf.lorbach@gmx.de
authors.forename: Olaf
authors.initials: O
authors.lastname: Lorbach
authors.forename: Matthias
authors.initials: M
authors.lastname: Kieb
authors.forename: Florian
authors.initials: F
authors.lastname: Raber
authors.forename: Lüder C
authors.initials: LC
authors.lastname: Busch
authors.forename: Dieter M
authors.initials: DM
authors.lastname: Kohn
authors.forename: Dietrich
authors.initials: D
authors.lastname: Pape
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008297:Male; D019651:Plastic Surgery Procedures / Q000379:methods; D012399:Rotation; D017006:Rotator Cuff / Q000502:physiology / Q000601:surgery*; D000070636:Rotator Cuff Injuries; D013536:Suture Techniques; D013708:Tendon Injuries / Q000601:surgery*