engleski

Biomechanical testing of arthroscopic transosseous versus double row technique of rotator cuff repair – in vitro and in vivo study in sheep

Purpose The study analysed primary fixation strength and strength after biological healing 3 months after reconstruction of infraspinatus tendon in sheep shoulder employing two methods - arthroscopic transosseous and double row technique. Materials and Methods Twentyfour cadaver sheep infraspinatus insertions were divided in 3 equal groups ; reattachment by arthroscopic transosseous suture anchor technique with 2 anchors, refixation with double row anchor technique using 3 anchors and 8 shoulders were controls. Twelve adult sheep were randomized into two groups: transosseous group and double-row group. Infraspinatus tendon insertion area was resected in both groups. In transosseous group, transosseous tunnel was created through the greater tuberosity. Fastin anchor with Orthocord was placed at the penetrator's exit site on the footprint. The lateral limb of the suture passed through the transosseous tunnel, the other limb of the suture passed through the infraspinatus tendon. The second suture from the anchor was passed through the infraspinatus tendon as a mattress suture. Two Fastin anchor were used. In double group reconstruction of the infraspinatus was performed in standard fashion using three Fastin, two lateral and one medial. There was no immobilization after surgery. Sheep were sacrificed after 3 months. All specimens were put in Universal Testing Machine on the unique way, preloaded with 10 N and distracted 1 mm/s. Full breaking force after continuous distraction was measured in all groups. Results Arthroscopic transosseous group had greater terminal force requred for breakage of tendon-bone construct than double row group (average 160 N and 137 N respectively in vitro immediately after reconstruction, and average 302 N and 246 N respectively in vivo three months after reconstruction). But both techniques form significantly weaker construct that is natural. In control group breaking force was at average 627 N. Discussion / Conclusion Arthroscopic transosseous technique with 2 anchors is primary stronger than double row technique with 3 anchors, and despite enlarged tendon to bone contact, both techniques are much weaker than is original tendon insertion. The results implicate importance of postoperative imobilisation and slow motion programme. Transosseous suture anchor technique has greater mechanical strength after biological healing of the infraspinatus tendon in sheep compared with double row technique.

reconstruction of infraspinatus tendon; biomechanical testing; artrhroscopic transosseous technique; double row technique

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