Abstract
The study objective was to assess if the mechanical properties of Polylactic Acid (PLA) bio-absorbable suture anchors vary with temperature? Bio-absorbable suture anchors may offer advantages over metal anchors. However, their performance at body temperature has been questioned in recent literature (Meyer et al). In particular, constant tension at body temperature caused early failure at the anchor eyelet. Using a previously validated mechanical jig, 15 standard locked sliding arthroscopic knots (Duncan Loop + three alternate hitches) were tied by the senior author using PAN-ALOK anchors (DEPUY MITEK, Edinburgh, UK) and ETHIBOND sutures (ETHICON) and placed under a standard constant tensile load reproducing the action of the surgically repaired rotator cuff. All anchors were loaded for at least five days to match previous studies. Eight were incubated at a constant 37°C and six were kept at room temperature. The elongation of the suture knot/anchor construct was assessed by a rheostat within the mechanical jig. Sample unused, room temperature and body temperature anchors were blindly analysed using plane polarized light microscopy with a graticule to assess deformation, concentrating on the eyelet region. Mean elongation of body temperature anchors = 0.461mm (0.159 – 0.952) Mean elongation of room temperature anchors = 0.278mm (0.159 – 0.793) Unpaired t-test: p=0.24 Microscopic analysis of the anchor material showed no difference in structural deformation in the three anchors. Our model suggests no significant increase in elongation at body temperature for this commonly used arthroscopic suture anchor / knot construct. This counters previous work. It gives us confidence to continue to use such devices.
The abstracts were prepared by Cormac Kelly. Correspondence should be addressed to The Secretary, British Elbow and Shoulder Society, Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE
