engleski

Biomechanical study of primary fixation strength in sheep shoulder

Purpose of the biomechanical study was to analyse fixation strength of covered footprint after reconstruction of infraspinatus in sheep shoulder employing two methods: arthroscopic transosseous and double row technique. Eighteen 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 controls. Tendon insertion was marked, and markation was done after particular type of reconstruction on each shoulder. After reconstruction using simulation of each arthroscopic reconstruction technique, all tendon-bone constructs and control shoulders were tested in materials testing system. MTS machine TA.HDplus Texture Analyser ; The Stable Micro Systems was used. All specimens were preloaded to 10 N and than subjected to static tensile loading at a displacement rate of 1 mm/s. Maximum load to failure was measured in all groups. Typical diagrams of three groups are shown in figures as follows: G1 - arthroscopic transosseous group, G2 - double row group and GK - control group. G1 arthroscopic transosseous group had significantly greater terminal force required for rupture of tendon-bone construct than G2 double row group (average 168 N and 137 N respectively). But both techniques form significantly weaker construct that is natural tendon-bone insertion in GK control group (average 630 N). Arthroscopic transosseous technique with 2 anchors is primary stronger than double row technique with 3 anchors ; both techniques are much weaker than is original tendon insertion. The results implicate importance of postoperative immobilisation and slow motion programme.

biomechanical analysis; mechanical testing; shoulder

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