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.
Patients undergoing total hip replacement (THR) often require further orthopaedic surgery including other primary lower limb joint replacements and revision surgery in their lifetime. We analysed the 10-year data of 552 patients who underwent primary total hip replacement between April 1991 and March 1992 at our institute. Data were available for all patients before the index operation. 77% of patients attended their 5-year review and 67% attended their 10-year review. 233 (42%) had had or subsequently had the opposite hip replaced. 30 patients (5%) had a knee replaced and 19 (3%) had both knees replaced. 4.4% underwent revision surgery.
Patients undergoing total hip replacement (THR) often require further orthopaedic surgery including other primary lower limb joint replacements and revision surgery in their lifetime. We analysed the 10-year data of 552 patients who underwent primary total hip replacement between April 1991 and March 1992 at our institute. Data was available for all patients before the index operation. 77% of patients attended their 5-year review and 67% attended their 10-year review. 233 (42%) had had or subsequently had the opposite hip replaced. 30 patients (5%) had a knee replaced and 19 (3%) had both knees replaced. 4.4% underwent revision surgery. Concluding, nearly half the total number of these patients will in due course require the opposite hip replaced. 13% will need another major joint surgery (ie revision or TKR). At £6138 for a primary THR and £8500 for revision THR, and the cost of radiographs (£60) and follow-up appointment (£60), the approximate cost implications on a conservative estimate are 13 million pounds. For a single surgeon undertaking 40 THRs in a single year the cost would be approximately £900,000. In addition, the surgeon in 10 years practice would create enough work to last him the rest of his working lifetime. These factors including cost implications and human resource requirements will have significant influence on future planning of health care trusts.
