To determine if force measured using a strain gauge in circular external fixation frames is different for 1) different simulated stages of bone healing, and for 2) fractures clinically deemed either united or un-united. In a laboratory study, 3 similar Ilizarov frame constructs were assembled using a Perspex bone analogue. Constructs were tested in 10 different clinical situations simulating different stages of bone healing including with the bone analogue intact, with 1,3 and 50mm gaps, and with 6 materials of varying stiffness's within the 50mm gap. A Bluetooth strain gauge was inserted across the simulated fracture focus, replacing one of the 4 threaded rods used to construct the frame. Constructs were loaded to 700N using an Instron testing machine and maximum force during loading was measured by the strain gauge. Testing was repeated with the strain gauge replacing each of the 4 threaded rods in turn, with measurements being repeated 3 times, across all 3 frame constructs for all 10 simulated clinical situations (n=360). Force measurements between the situations were compared using a Kruskal-Wallis test (KW) and a post-hoc Steel test was used for multiple comparison against control (intact bone model). Additionally, a pilot study has been initiated to assess clinical efficacy of the strain gauge measurement in patients with circular frames. The strain gauge replaced the anterior rod across the fracture focus for each patient. Patients were asked to step on a weighing scale with their affected limb, and maximum weight transfer through the limb and maximal force measured in the frame were recorded. This was repeated 3 times and a mean ratio of force to weight through affected limb was calculated for each patient. The clinical situation at each measurement was designated as united or un-united by one of the senior authors for analysis. Force measurements between the situations were compared using a Wilcoxon-Mann-Whitney test.Abstract
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METHODS
To compare the periprosthetic fracture mechanics between a collared and collarless fully coated cementless femoral stem in a composite femur. Two groups of six composite femurs (‘Osteoporotic femur’, SawBones, WA USA) were implanted with either a collared (collared group) or collarless (collarless group) cementless femoral stem which was otherwise identical by a single experienced surgeon. Periprosthetic fractures of the femur were simulated using a previously published technique. High speed video recording was used to identify fracture mechanism. Fracture torque and angular displacement were measured and rotational work and system stiffness were estimated for each trial. Results were compared between collared and collarless group and the comparison was evaluated against previously published work using fresh frozen femurs and the same protocol.Abstract
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To estimate the effect of calcar collar contact on periprosthetic fracture mechanics using a collared fully coated cementless femoral stem. Three groups of six composite femurs were implanted with a fully coated collared cementless femoral stem. Neck resection was increased between groups (group 1 = normal, group 2 = 3mm additional, group 3 = 6mm additional), to simulate failure to obtain calcar collar contact. Periprosthetic fractures of the femur were simulated using a previously published technique. Fracture torque and rotational displacement were measured and torsional stiffness and rotational work prior to fracture were estimated. High speed video recording identified if collar to calcar contact (CCC) occurred. Results between trials where calcar contact did and did not occur where compared using Mann-Whitney U tests.Abstract
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To estimate the effect of calcar collar separation on the likelihood of calcar collar contact during in vitro periprosthetic fracture. Three groups of six composite femurs were implanted with a collared cementless femoral stem. Neck resection was increased between groups (group 1 = normal, group 2 = 3mm additional, group 3 = 6mm additional), to simulate failure to obtain calcar collar contact. Prior to each trial, the distances between anterior (ACC) and posterior (PCC) collar and the calcar were measured. Periprosthetic fractures of the femur were simulated using a previously published technique. High speed video recording identified when collar to calcar contact (CCC) occurred. The ACC and PCC were compared between trials where the CCC was and was not achieved. Regression estimated the odds of failing to achieve CCC for a given ACC or PCC.Abstract
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Acute pain following total knee replacements (TKRs) is associated with higher peri-operative opiate requirements and their side effects, longer hospital stay and lower patient satisfaction (Petersen 2014). It may also be associated with higher rates of chronic pain at 1 and 5 years (Beswick 2012). We present a novel technique using combination of Local Infiltration Anaesthesia (LIA) with PainKwell infusion system (Bupivacaine 0.5 @ 4mls and 6mls/hr) to improve pain management following TKRs. Between October 2015 and March 2016. 110 patients undergoing primary TKR were prospectively studied. All patients studied had spinal anaesthesia (SA) with diamorphine. Demographics between the two groups were similar. Group 1. SA plus LIA plus traditional multimodal analgesia. 32 patients. Group 2. SA plus LIA plus PainKwell for 48 hours rate 4mls. 38 patients Group 3. SA plus LIA plus PainKwell for 48 hours rate 6mls. 40 patientsBackground
Methods
Hip arthroplasties are associated with high postoperative pain scores. In some reports, moderate to severe pain was 58% on the first day postoperatively in total hip replacements (THRs). Several techniques are currently used at our institution to tackle acute pain following THRs. These include: 1) Spinal anaesthetic (SA) with Diamorphine only; 2) General anaesthetic (GA) only; 3) SA with local infiltration anaesthetic mixture 1 (LIA1,). Mixture 1 consisted of ropivacaine, adrenaline, and ketorolac; 4) SA with LIA mixture 2 (LIA2). Mixture 2 consisted of bupivacaine and adrenaline; 5) SA with LIA1 and PainKwell pump system. In this study we report on the techniques of acute pain control following THR at our regional centre for elective primary THRs. Between June 2011 and July 2014, 173 consecutive patients undergoing primary THR using the posterior approach were prospectively followed up. Group 1. GA only. 31 patients, Group 2. SA only. 37 patients, Group 3. SA plus LIA1 only. 38 patients, Group 4. SA plus LIA2 only, 34 patients, Group 5. SA plus LIA1 plus PainKwell Pump System for 48 hours. 33 patients.Background
Methods
Pain control following knee replacement (TKR) surgery is often poor. Moderate to severe pain is often reported in the first 48 hours following surgery requiring opiate analgesia. The Local Infiltration Anaesthetic (LIA) technique has been described as a method to reduce post operative pain. In this study we report on our experience using LIA in addition to the PainKwell system (Peak Medical) of continuous infusion intra-articularly, of 0.25% bupivacaine at 4–5 mls/hour for 48 hours post surgery. The PainKwell catheter is placed in the knee joint during surgery. Between the June 2012 and Sep 2012, 62 patients undergoing primary TKR were prospectively followed up. All patients studied had spinal anaesthesia (SA) with diamorphine. Group 1. GA. No LIA and no PainKwell. 20 patients. Group 2. SA plus LIA plus PainKwell for 48 hours post operatively with catheter placed anteriorly under the patella. 21 patients. Group 3. SA plus LIA plus PainKwell for 48 hours post operatively with catheter placed posteriorly in the knee joint. 21 patients.Background
Methods
