Introduction: Reconstruction of the original footprint of the supraspinatus tendon is mandatory in achieving proper clinical result after reconstrucitve rotator cuff surgery.

Methods: Twenty four cadaveric sheep shoulder and 12 live sheep sacrificed 3 months after rotator cuff reconstruction were tested. Arthroscopic transosseous technique and double row techniques were compared according to static load immediately after reconstruction (sheep cadaver) and after tissue healing took place (in vivo on sheep). In clinical work we analysed results of 120 patients operated on by the senior author employing different arthroscopic Methods: of rotator cuff reconstructionas.

Results: Transosseous technique and double row technique have comparable biomechanical primary ultimate load to failure (160 N and 137 N comparatively) and equal ultimate load to failure after the tissue heals (302 N and 246 N respectively). Immediately after the reconstruction in double row group we noticed significant fragility in comparison to elasticity of the tendon-bone complex in transosseous group. We operated 67 shoulders (56%) with arthroscopic transosseous technique. We did not noticed complications of bone anchor, but in two patients we had rerupture of sutures that had to be reoperated on.

Discussion: Arthroscopic transosseous technique uses less amount of bone anchors, optimaly reconstructs “footprint”, and has equal ultimate static load to failure as double row technique. But, double row technique is much more fragile than transosseous method in immediate postoperative period. Arthroscopic transosseous technique is technicaly demanding procedure that guarantee optimal clinical result.

Purpose: The study in vitro compares primary fixation strength of two arthroscopic flip knots; clinical knot security and ultimate load to failure. SMC knot is well known and frequently used arthroscopic knot. SAK (Secure Arthroscopic Knot) is fully instrumental knot, easy to master, with short learning curve. Published 10 years ago, during that period it is predominantly used by senior author in arthroscopic shoulder procedures.

Materials and Methods: Curved metal rods are put in grips of the Universal Testing Machine and positioned centraly in vertical orientation 5 mm apart. The curvature of each rod was wrapped with 2 mm deerskin soaked in saline. Arthorscopic canulla was positioned in holder on the same position during testing procedure for all knots. Knots – 8 SAK and 8 SMC – were constructed outside the canulla, slided and positioned with arthroscopic knot pusher on the concave side of the caudal rod. Four additional loops (left-right alternatively) were put on the knot. Orthocord was used in all procedures, and all knots were performed by the same surgeon. The construct was preloaded with 7 N and distracted 0, 1mm/s. Ultimate tensile load (UF) and clinical load to failure (CF) were determined. Clinical load to failure is defined as force that distract knot for 3 mm. Data distribution was analysed and parametric statistics was performed.

Results: Clinical failure for SAK is 249±29 N, and for SMC 191±40 N, and this difference is significant on the level of 5 %. Ultimate failure of SAK is 292±34 N and for SMC 276±39 N, and this difference is not significant. SAK failured with breakage in 7 out of 8 measurments, and SMC failured equaly by slipage and breakage.

Discussion/Conclusion: The study imitated in vivo condition, slipage of knots during test was eliminated using deerskin which simulated human tissue. Both knots are equally strong regarding ultimate load to failure in hands of the experienced shoulder arthroscopist. Secure arthroscopic knot (SAK) presented greater load to clinical failure comparing with SMC knot. Autors can recomend SAK as an easy and safe arthroscopic flip knot.