Abstract. Objectives. The purpose of this study was to determine the cost of inpatient admissions for developmental dysplasia of the hip (DDH) at a UK tertiary referral centre, and identify any association between newborn screening (NIPE) status and the cost of treatment. Methods. This was a retrospective study, using hospital episodes data from a single NHS trust. All inpatient episodes between 01/01/2014 to 30/06/2019 with an ICD-10 code stem of Q65 ‘congenital deformities of hip’ were screened to identify admissions for management of DDH. Data was subsequently obtained from electronic and paper records. Newborn screening status was recorded, and patients were divided into ‘NIPE-positive’ (diagnosed through selective screening) and ‘NIPE-negative’ (not diagnosed through screening). Children with neuromuscular conditions or concomitant musculoskeletal disease were excluded. The tariff paid for each inpatient episode was identified, and the number of individual clinic attendances, surgical procedures and radiological examinations performed (USS, XR, CT, MRI) were recorded. Results. 41 patients with DDH were admitted for inpatient management. 44% (n = 18) were NIPE-positive, diagnosed mean age 6.7 weeks. 56% (n = 23) were NIPE-negative, diagnosed mean age 26 months. The total cost of inpatient care in the NIPE-positive group was £171,471 (£9,526.18 per-patient) compared to £306,615 (£13,331.10 per-patient) for NIPE-negative. In the NIPE-positive group, there were 99 clinic attendances, 47 inpatient admissions and 160 radiological examinations performed (36 USS, 107 XR, 17 CT). This compared to 148 clinic attendances, 59 inpatient admissions and 215 radiological examinations (187 XR, 26 CT, 2 MRI) in the NIPE-negative group. Conclusion. A greater proportion of inpatient admissions for DDH are among NIPE-negative children. They incur a higher cost of treatment per patient and necessitate more inpatient resources. This study adds to the ongoing conversation around the cost-effectiveness of selective screening for DDH in the UK. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Background. Stress shielding and wear induced aseptic loosening cause failure in arthroplasty surgery. To improve survivorship, the use of a low modulus, low wearing biomaterial may be a suitable alternative to hard bearing prostheses, such as cobalt chromium (CoCr). There has been considerable research interest in the use of polyetheretherketone (PEEK) based on observed clinical success especially in spinal surgery. This study investigated the wear performance of PEEK, carbon reinforced PEEK (CFR-PEEK) and acetal as bearing materials in an all polymer total knee arthroplasty (TKA) using a unidirectional pin on plate test. Methods. The following material combinations were tested: PEEK vs. UHMWPE, CFR-PEEK vs. UHMWPE, PEEK vs. PEEK, CFR-PEEK vs. PEEK, CoCr vs. UHMWPE, PEEK vs. XLPE, CFR-PEEK vs. CFR-PEEK, PEEK vs. Acetal, Acetal vs. XLPE and CoCr vs. XLPE.Tribological couples tested (Pin vs. Plate) Using a previously validated modification of ASTM F732, 20mm diameter spherically ended pins with a radius of 25mm were articulated against 40mm diameter plates. A load of 1000N was applied to generate a contact stress of about 70MPa similar to contact stresses previously reported in the knee. The lubricant used was 25% newborn calf serum containing 0.3% sodium azide to retard bacteria growth and 20mM EDTA to prevent calcium deposition. Three repeats of pin on plate combinations (including 2 passive soak controls) were tested for 2 million cycles at a cycle frequency of 1Hz and a stroke length of 10 mm. Gravimetric wear was analysed every 250,000 cycles and results converted to volumetric wear using material density. Results. All CFR-PEEK articulations were stopped due to excessive wear of the counter-surfaces. Results showed a linear wear rate of UHMWPE and XLPE plates over the test period. PEEK vs. XLPE showed similar wear rate to metal on polyethylene (MoP) bearings. Conclusion. At stresses representative of the knee, PEEK pins when articulated against XLPE plates generated volumetric wear similar to that noted in MoP bearings

Based on a study using a retrograde neurotracer, we have previously found that the dorsal portion of the L5/6 disc in the rat is multisegmentally innervated by dorsal root ganglia (DRG) from the level of T13 to L6, and that sensory nerve fibres from DRG of T13, L1 and L2 pass through the paravertebral sympathetic trunks. In this study in newborn rats, we injected crystals of 1,1′-dioctadecyl-3,3,3′,3′-tetramethylinedocarbocyanine perchlorate (DiI) into the DRG of T13, L1 and L2 and showed DiI-labelled sensory nerve fibres in the dorsal portion of the discs from the level of T13/L1 to L5/6. Our results show that the dorsal portion of the lumbar discs is innervated by the DRG from levels T13 to L2

Hip simulators have been used for ten years to determine the tribological performance of large-head metal-on-metal devices using traditional test conditions. However, the hip simulator protocols were originally developed to test metal-on-polyethylene devices. We have used patient activity data to develop a more physiologically relevant test protocol for metal-on-metal devices. This includes stop/start motion, a more appropriate walking frequency, and alternating kinetic and kinematic profiles.

There has been considerable discussion about the effect of heat treatments on the wear of metal-on-metal cobalt chromium molybdenum (CoCrMo) devices. Clinical studies have shown a higher rate of wear, levels of metal ions and rates of failure for the heat-treated metal compared to the as-cast metal CoCrMo devices. However, hip simulator studies in vitro under traditional testing conditions have thus far not been able to demonstrate a difference between the wear performance of these implants.

Using a physiologically relevant test protocol, we have shown that heat treatment of metal-on-metal CoCrMo devices adversely affects their wear performance and generates significantly higher wear rates and levels of metal ions than in as-cast metal implants.