Introduction

The health sector contributes the equivalent of 4.4% of global net emissions to the climate carbon footprint. It has been suggested that between 20% and 70% of health care waste originates from a hospital's operating room, the second greatest component of this are the textiles used, and up to 90% of waste is sent for costly and unneeded hazardous waste processing.

Waste from common orthopaedic operations was quantified, the carbon footprint calculated, and cost of disposal assessed. A discussion of the circular economy of textiles, from the author of the textile guidance to the Green Surgery Report follows.

Introduction

Flexor sheath infections require prompt diagnosis, and management with intravenous antibiotics and/or surgical washout followed by physiotherapy. Complication rates as high as 38% have been reported.

Fractures of the neck of femur are common in the older adult with significant morbidity and mortality rates. This patient cohort is associated with frailty and multiple complex medical and social needs requiring a multidisciplinary team to provide optimal care. The aim of this study was to assess the outcomes at 5 years following implementation of a collaborative service between the Orthopaedic and Geriatric departments of Southland Hospital in 2012.

Retrospective data was collected for patients aged 65 years and older who were admitted with a fragility hip fracture. Data was collated for 2011 (pre-implementation) and 2017 (post-implementation). Demographics and ASA scores were recorded. We assessed 30-day and 1-year mortality, surgical data, length of stay and complications.

There were 74 patient admissions in 2011 and 107 in 2017. Mean age at surgery was 84.2 years in 2011 and 82.6 years in 2017 (p>0.05). Between the 2011 and 2017 groups there has been a non-significant reduction in length of stay on the orthopaedic ward (9.8 days vs 7.5 days, p=0.138) but a significant reduction in length of stay on the rehabilitation ward (19.9 vs 9 days, p<0.001). There was a significant decrease in frequency of patients with a complication (71.6% vs 57%, p=0.045) and a marginal reduction in number of complications (p=0.057). Through logistic regression controlling for age, sex and ASA score, there was a reduction in the odds of having a complication by 12% between 2011 and 2017 (p<0.001). There was no difference in mortality between the groups.

The orthogeriatric model of care at Southland Hospital appears to have reduced both the frequency of complications and length of stay on the rehabilitation ward 5 years after its implementation. This is the first study in New Zealand demonstrating medium-term post-implementation follow-up of what is currently a nationally accepted standard model of care.

Studies have indicated that the shallow Ultra High Molecular Weight Polyethylene (UHMWPE) acetabular socket or the socket with no head center inset can significantly increase the risk of hip joint dislocation. A previous study suggested the rim loading model in UHMWPE socket and metal femoral head can generate an intrinsic dislocating force component pushing head out of socket. Recently there has been renewed interest in dual mobility articulations due to the excellent stability. The outer bearing couple of the dual mobility articulations are comprised of the UHMWPE femoral head and metal acetabular socket while inner bearing is the locked conventional metal-poly construct. The acetabular socket is also featured by an anatomically shaped head inset wall. The purpose of this study was to theoretically compare the intrinsic dislocating force between conventional metal head on UHMWPE socket articulations and the poly head on metal socket articulations used in the dual mobility cup under direct loading.

The 3-D finite element analysis (FEA) models were same as previous study but with different material combinations. Sixty FEA model assemblies were consisted of CoCr or UHMWPE femoral heads and their corresponding 10mm thick generic UHMWPE or CoCr acetabular sockets. There were five different head center insets of 0, 0.5, 1, 1.5 and 2mm for each of six bearing diameters of 22, 28, 32, 36, 40 and 44mm for either sockets. The joint load of 2,446N was applied through the femoral head center as the same fashion as previous study. The dislocating force generated by the joint loading force intrinsically pushed femoral head out of socket. FEA results were verified with two data points of physical testing of actual UHMWPE 28mm ID liners with 0 and 1.5mm head center insets.

The highest dislocating force was 1,269N per 2,446N of rim loading force for the 0mm head center inset in poly cup with 22mm CoCr femoral head or the case of easiest to dislocate. The lowest dislocating force was 17.7N per 2,446N force for the 2mm inset in CoCr socket with 44mm poly head which therefore was the least likely to dislocate. The average dislocating force decreased by 78% from metal head- poly cup couple to poly head - metal cup couple. The dislocating force decreased as the head center inset and head size increased in all material cases.

The study suggests that not only the head center inset and head size but also the bearing material combinations can affect the intrinsic dislocating force component. The dual mobility poly head and metal socket couple generates less intrinsic dislocating force in all comparable conditions for conventional metal head and poly socket couple. During the hip separation and vertical placement of the cup, all variables found in this study may play the important rules to maintain joint stability. The stiffened cup rim reduces the deformation and thus reduces the potential cup wedge effect to generate dislocating force. The result of this study should provide the guidance to improve acetabular cup design for better joint stability.