Thermally treated 1st generation highly crosslinked polyethylenes (HXLPE) have demonstrated reduced penetration and osteolysis rates, however, concerns still remain with respect to oxidative stability and mechanical properties of these materials. To address these concerns, manufacturers have introduced the use of antioxidants to quench free radicals while maintaining the mechanical properties of the HXLPE. Two common antioxidants are α-tocopherol (Vitamin-E) and pentaerythritol tetrakis (PBHP). These may be either mixed prior to consolidation, or diffused throughout the polymer after consolidation and irradiation. Between 2010 and 2015, 73 anti-oxidant HXLPE components were collected as a part of an IRB approved, multi-institutional retrieval analysis program during routine revision surgery. Of the seventy-three components, 30 (41%) were acetabular liners, whereas, 43 were tibial inserts. The components were fabricated from three different materials: Vitamin-E Diffused HXLPE (n=30; E1, Biomet), Vitamin-E Blended (n = 41; Vivacit-E, Zimmer) and PBHP blended (n = 2, AOX, DePuy). The hip and knee components were implanted for 0.7 ± 0.8 years (Range: 0.0–2.25 years) and 0.8 ± 1.1 years (Range: 0.0–4.5 years), respectively. Implantation time, patient weight, age, gender, and activity levels were similar between hip and knee components (Table 1). For oxidation analysis, thin slices (∼200μm) were taken from medial condyle and central eminence of the tibial inserts or the superior/inferior axis from hip components. The slices were boiled in heptane for six hours to extract lipids absorbed Introduction
Methods
The study was designed to look at canine related injuries presenting to the orthopaedic department at a small rural district general hospital and to assess their cost to the NHS. A retrospective review of case notes and x-rays of all dog related injuries presenting to the orthopaedic services at our hospital over a one year period starting January 2011 was undertaken. The injuries involved and the treatment provided along with the direct financial cost of these services were calculated from trust tariffs. Dog related injuries accounted for 84 out of a total of 48,405 patients presenting to the accident and emergency services over the index period. Of these, 29 required orthopaedic input with 57% of injuries resulting from trying to restrain a dog and the rest from being attacked by a dog. 14 patients were admitted to the wards with 11 among them requiring orthopaedic interventions ranging from wound wash outs and debridement to open reduction and internal fixation of fractures. These procedures cost £38,951 to the NHS. There were a total of 38 inpatient days involved costing another £9,196. A further 28 clinic visits were billed at £4,032. The total cost for the orthopaedic services provided was £52,179. There were no mortalities associated with these injuries over the time period. Canine related injuries are costly and avoidable. General public awareness of the problem coupled with appropriate legislation and its strict enforcement may be necessary to protect people from our canine companions.
