Soft systems methodology: a context within a 50-year retrospective of OR/MS

Soft systems methodology (SSM) has been used in the practice of operations research and management science OR/MS) since the early 1970s. In the 1990s, it emerged as a viable academic discipline. Unfortunately, its proponents consider SSM and traditional systems thinking to be mutually exclusive. Despite the differences claimed by SSM proponents between the two, they have been complementary. An extensive sampling of the OR/MS literature over its entire lifetime demonstrates the richness with which the non-SSM literature has been addressing the very same issues as does SSM

Parametric design optimisation of proximal humerus plates based on finite element method

Optimal treatment of proximal humerus fractures remains controversial. Locking plates offer theoretical advantages but are associated with complications in the clinic. This study aimed to perform parametric design optimisation of proximal humerus plates to enhance their mechanical performance. A finite element (FE) model was developed that simulated a two-part proximal humerus fracture that had been treated with a Spatial Subchondral Support (S3) plate and subjected to varus bending. The FE model was validated against in vitro biomechanical test results. The predicted load required to apply 5 mm cantilever varus bending was only 0.728% lower. The FE model was then used to conduct a parametric optimisation study to determine the orientations of inferomedial plate screws that would yield minimum fracture gap change (i.e. optimal stability). The feasible design space was automatically identified by imposing clinically relevant constraints, and the creation process of each FE model for the design optimisation was automated. Consequently, 538 FE models were generated, from which the obtained optimal model had 4.686% lower fracture gap change (0.156 mm) than that of the manufacturer’s standard plate. Whereas its screws were oriented towards the inferomedial region and within the range of neck-shaft angle of a healthy subject. The methodology presented in this study promises future applications in patient-specific design optimisation of implants for other regions of the human body

Should We Resect Hoffa's Fat Pad during Total Knee Replacement?

Resection of Hoffa's fat pad during total knee arthroplasty is sometimes performed to improve access and view. Opponents of this technique argue that sacrificing the fat pad potentially compromises blood supply to the patellar tendon and it can subsequently shorten. Our objective was to identify any difference in the Insall-Salvati ratio of knees undergoing total knee arthroplasty between a cohort that had Hoffa's fat pad preserved and the one that had Hoffa's fat pad completely excised. The total knee arthroplasties by two surgeons at our institution were reviewed over a 3-year period. Surgeon A routinely preserves the fat pad and surgeon B routinely excises the fat pad. Radiographs preoperatively, immediately postoperatively, and at a minimum of 1-year follow up were analyzed for the Insall-Salvati ratio. A total of 161 knees were reviewed, 65 in the preserved group and 96 in the excised group with a mean age of 67 and 70 years, respectively. The mean preoperative Insall-Salvati ratio for the preserved group was 1.12 (±0.145) and excised group 1.16 (±0.168) (p = 0.094). The mean immediate postoperative Insall-Salvati ratio for the preserved group was 1.10 (±0.154) and for excised group 1.18 (±0.194). The difference in Insall-Salvati ratio from preoperative to the immediate postoperative period in the preserved group compared with the excised group demonstrated a significant difference (p = 0.010). However, the change of Insall-Salvati ratio at 1 year did not significantly differ between the groups (p = 0.059). There does not appear to be any difference in the Insall-Salvati ratios of both groups at 1 year's follow up; therefore, this study radiologically at least supports the use of either technique

An observational study evaluating the efficacy of microfragmented adipose tissue in the treatment of osteoarthritis

Aim: Osteoarthritis (OA) prevalence is increased in ageing and obese populations. This prospective single-arm cohort study aimed to investigate the efficacy of autologous microfragmented adipose tissue treatment of severe knee or shoulder OA. Materials & methods: Participants received an intra-articular microfragmented adipose tissue injection to the affected joint(s). Multiple patient reported outcome measures (PROMS) were recorded from 0 to 52 weeks for 63 consecutive joints. Results: Compared with baseline, there were significant improvements in all PROMS from 2 to 12 weeks and maintained at 52 weeks. Regression analysis revealed an inverse correlation with BMI and change in PROMS for knee joints. Conclusion: Our observed findings suggest this approach represents a safe, effective treatment for moderate-to-severe knee and shoulder OA, although efficacy may be reduced with increasing obesity. Swelling and pain in the joints is common and found more often in older and overweight people. Osteoarthritis causes swelling and pain in joints because of a loss of tough, flexible tissue called cartilage. This study looks to see if injection of fat tissue into knee or shoulder joints can improve symptoms. The fat tissue used was called microfragmented adipose tissue (MFAT). This uses a technique to break down the fat tissue before injection. These cells were from the patient's own body. All patients had an injection of MFAT into their painful joints. In total, 59 patients took part. Reports were directly collected from the patient of how well they were doing. This was done before and after the injection at weeks 2, 6, 12, 24 and 52. There were three different types of report collected for knee joints and three for shoulder joints. Scores were then compared from these reports to see if there was a difference. An improvement was found in all three of the combined reports for both knees and shoulders. This stayed until 52 weeks. BMI is a measure of body weight in relation to height. Patients with a higher BMI were found to have had a smaller improvement in their scores. This study shows MFAT injections are safe and effective in treating painful joints