Biotribological behaviour, biodegradability and osteocompatibility of Mg-3Zn/HA composite based intramedullary inserts in avian model.

Bioactivity, structural integrity and tribological behaviour of biodegradable orthopaedic fracture fixing accessories considerably impact their actual performance in the body environment. Immune system in the living body quickly responds to the wear debris as foreign material and begins a complex inflammatory response. Magnesium (Mg) based biodegradable implants are widely studied for temporary orthopaedic applications, due to their similar elastic modulus and density to natural bones. However, Mg is highly vulnerable to corrosion and tribological damage in actual service conditions. To address these challenges via a combined approach, the Mg-3 wt% Zinc (Zn)/x hydroxyapatite (HA, x = 0, 5 and 15 wt%) based composites (fabricated via spark plasma sintering route) are evaluated in terms of biotribocorrosion and in-vivo biodegradation and osteocompatibility behaviour in an avian model. The addition of 15 wt% HA in the Mg-3Zn matrix has significantly enhanced the wear and corrosion resistance in the physiological environment. X-ray radiograph analysis of the Mg-HA-based intramedullary inserts implanted in the humerus bone of birds showed consistent progression of degradation and positive tissue response up to 18 weeks. The 15 wt% HA reinforced composites have shown better bone regeneration properties than other inserts. This study provides new insights into developing next-generation Mg-HA-based biodegradable composites for temporary orthopaedic implants, with excellent biotribocorrosion behaviour.

Randomized Controlled Study Using Ropivacaine with Intravenous Adjuvants in Spinal Anaesthesia In Lower Limb Surgeries.

BACKGROUND: In recent years, several adjuvants have been used to prolong the duration of the subarachnoid block. These adjuvants have either been used via intrathecal route or intravenous (i.v.) route. Dexmedetomidine and clonidine have been used as adjuvants to local anesthetic drugs by intrathecal, epidural, caudal, and i.v. routes and for peripheral nerve blocks. In this study, we endeavored at finding the efficacy of dexmedetomidine and clonidine in improving the analgesia quality and duration of the subarachnoid block. SETTING AND DESIGN: A prospective, double-blind, randomized control trial comprising 70 subjects posted for elective lower limb surgeries. MATERIALS AND METHODS: Seventy patients were selected at random and were allocated to two groups (Group C and Group D) of 35 each. In Group C, the patients received isobaric ropivacaine with clonidine 1.0 µg.kg-1 intravenously. In Group D, the patients received isobaric ropivacaine with dexmedetomidine 0.5 µg.kg-1 intravenously. Perioperatively, heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, and oxygen saturation were recorded and documented every 5 min till the end of surgery. Time of onset, level of sensory blockade, and duration of sensory blockade were recorded. Motor block was assessed using modified Bromage scale. Data validation and analysis were carried out by SPSS version 16. A P < 0.05 was considered statistically significant. RESULTS: Time of onset of sensory block in Dexmedetomidine group and Clonidine group was 2.70 ± 1.25 minutes and 3.50 ± 1.23 minutes respectively (P = 0.021). Time of onset of motor block in Dexmedetomidine group and Clonidine group was 3.55 ± 1.60 minutes and 4.30 ± 1.45 minutes respectively (P = 0.034). Time for 2 segment regressions of sensory block in Dexmedetomidine group and Clonidine group was 140.30 ± 12.32 minutes and 125.65±14.33minutes respectively (P = 0.047). Time of regressions of motor blockade to Bromage Scale 1 in Dexmedetomidine group and Clonidine group was 148.65 ± 15.23 minutes and 129.70 ± 19.35 minutes respectively (P = 0.032). CONCLUSION: The use of i.v. dexmedetomidine perioperatively prolongs the duration of sensory and motor block significantly when compared to i.v. clonidine.