Temperature changes and chondrocyte death during drilling in a bovine cartilage model and chondroprotection by modified irrigation solutions.

PURPOSE: Drilling into cartilage/bone is often required for orthopaedic surgery. While drilling into bone has been studied, the response of cartilage has received little attention. We have measured cartilage and drill bit temperatures during drilling and quantified the zone of chondrocyte death (ZCD) around the hole in the presence/absence of irrigation solutions. METHODS: Drilling was performed using a 1.5-mm orthopaedic drill bit applied to bovine metatarsophalangeal joints and temperatures recorded by infrared camera. Osteochondral explants were then incubated with 5-chloromethylfluorescein diacetate (CMFDA) and propidium iodide (PI) to label living/dead chondrocytes respectively. The width of the ZCD was quantified by confocal laser scanning microscopy (CLSM) and image analysis. RESULTS: Without irrigation, the ZCD following drilling for two seconds was 135 ± 15 µm and this increased (>fourfold, P < 0.001) with five seconds of drilling. Irrigation reduced the ZCD following drilling for both two and five seconds (P < 0.05, P < 0.001 respectively) to the same level (approx. 60 µm). Without irrigation, drill bit and cartilage temperature increased rapidly to >265 and 119 °C respectively, whereas the camera saturated at >282 °C during drilling for five seconds. With irrigation, the drill bit temperature was significantly reduced during drilling for two and five seconds (approx. 90 °C) with negligible change in cartilage temperature. Drilling while irrigating with hyperosmotic saline (600 mOsm) reduced (P < 0.01) the ZCD compared to saline, whereas chondrocyte death was increased (P < 0.01) by Ca(2+) saline (5 mM). CONCLUSIONS: Reducing temperature during drilling by irrigation markedly suppressed, but did not abolish chondrocyte death. Optimising the irrigation solution by raising osmolarity and reducing Ca(2+) content significantly reduced chondrocyte death during drilling and may be clinically beneficial.

Cognitive outcome after on- and off-pump coronary artery bypass grafting surgery: a systematic review and meta-analysis.

OBJECTIVE: The aim of this study was to compare cognition following coronary artery bypass grafting (CABG) surgery with or without cardiopulmonary bypass (CPB) (on- or off-pump). DESIGN: Systematic review and meta-analysis of randomized control trials comparing cognitive outcome in patients undergoing CABG surgery on- or off-pump as assessed by continuous measures from a battery of 7 psychometric tests. SETTING: Multi-institutional centers performing CABG surgery. PARTICIPANTS: Patients with coronary artery disease requiring CABG surgery. INTERVENTIONS: CABG surgery with or without CPB. MEASUREMENTS AND MAIN RESULTS: A structured literature search identified 13 randomized control trials that included a total of 2,405 patients. Results from 7 psychometric tests were grouped into early (≤3 months) and late (6-12 months) postoperative periods. No significant differences were found between on- and off-pump groups in any of the 7 psychometric tests in either the early (p range 0.21-0.78) or late (p range 0.09-0.93) postoperative period. CONCLUSION: The results suggested that CPB may not be associated with cognitive decline that is associated with CABG surgery.