Chondroprotection of articular cartilage integrity: Utilizing ultrasonic scalpel and hyperosmolar irrigation solution during cutting.

Objectives: Ultrasonic (US) cutting of cartilage in orthopaedic surgery has received little attention despite its potential to reduce chondrocyte death which could enhance cartilage repair. We aimed to investigate whether an ultrasonically-vibrating scalpel to cut human articular cartilage could reduce chondrocyte death, and to determine if hyper-osmolarity could provide chondroprotection during the procedure. Methods: A scalpel (no. 15) was mounted on an ultrasonic transducer to resonate at 35 ​kHz with 30 ​μm vibrational displacement. Thirty-six fresh human femoral cartilage samples were divided into four groups based on ultrasonic activation (US or non-US) and saline osmolarity (300 or 600 mOsm/L). Cell viability was assessed using a live/dead cell assay and analysed quantitatively by confocal microscopy. Histology illustrated tissue surface changes at the cut site. Results: The overall chondrocyte death percentage at both the US and non-US cut sites showed comparable results (p ​> ​0.05) in both osmolarities. However, the zone of chondrocyte death was reduced by 31 ​± ​5% and 36 ​± ​6%, respectively, when comparing US cutting at 300 mOsm/L and 600 mOsm/L to the control group (non-US cutting; 300 mOsm/L) (p ​< ​0.05). The width of the cut was consistent at both sites, regardless of the method of cutting. Conclusion: Cutting human cartilage with US in the presence of 300 or 600 mOsm/L media was chondroprotective compared to normal (non-US) scalpel cutting in 300 mOsm/L medium. These results suggest chondroprotection can be achieved while cutting using a US scalpel and raised osmolarity, potentially improving cartilage regeneration and repair following injury.