Abrasive water jet cutting as a new procedure for cutting cancellous bone—In vitro testing in comparison with the oscillating saw

Abstract

The quality of bone cuts is assessed by the accuracy and biological potency of the cut surfaces. Conventional tools (such as saws and milling machines) can cause thermal damage to bone tissue. Water jet cutting is nonthermal; that is, it does not generate heat. This study investigates whether the abrasive jet cutting quality in cancellous bone with a biocompatible abrasive is sufficient for the implantation of endoprostheses or for osteotomies. Sixty porcine femoral condyles were cut with an abrasive water jet and with an oscillating saw. alpha-lactose-monohydrate was used as a biocompatible abrasive. Water pressure (pW = 35 and 70 MPa) and abrasive feed rate (m = 0.5, 1, and 2 g/s) were varied. As a measure of the quality of the cut surface the cutting gap angle (delta) and the surface roughness (Ra) were determined. The surface roughness was lowest for an abrasive feed rate of m = 2 g/s (jet direction: 39 +/- 16 microm, advance direction: 54 +/- 22 microm). However, this was still significantly higher than the surface roughness for the saw group (jet direction: 28 +/- 12 microm, advance direction: 36 +/- 19 microm) (p < 0.001 for both directions). At both pressure levels the greatest cutting gap angle was observed for a mass flow rate of m = 1 g/s (pW = 35 MPa: delta = 2.40 +/- 4.67 degrees ; pW = 70 MPa: delta = 4.13 +/- 4.65 degrees), which was greater than for m = 0.5 g/s (pW = 35 MPa: delta = 1.63 +/- 3.89 degrees ; pW = 70 MPa: delta = 0.36 +/- 1.70 degrees) and m = 2 g/s (pW =70 MPa: delta = 0.06 +/- 2.40 degrees). Abrasive water jets are suitable for cutting cancellous bone. The large variation of the cutting gap angle is, however, unfavorable, as the jet direction cannot be adjusted by a predefined value. If it is possible to improve the cutting quality by a further parameter optimization, the abrasive water jet may be the cutting technique of the future for robotic usage.

Intraosseous heat generation during sonic, ultrasonic and conventional osteotomy

“…While accuracy is not always the critical factor, the biological potency of the bone at the cut surfaces is very important for the post-osteotomy callus formation and healing (Schwieger et al, 2004). The biological potency of the cut surface is directly influenced by the induced temperature increase during the osteotomy.…”

Waterjet—An innovative tool for manufacturing

“…The system cuts with minimal contaminated waste producing only a dry dust as the bi-product. In the medical industry water soluble, pharmalogically safe, biocompatible abrasives such as disaccharides, sugar, alcohols, amino acids and salt have been used for cutting, for example ␣ lactose monohydrate was used to cut cancellous bone (Schwieger et al, 2004). These are growing fields of research and may present some interesting transfer of waterjet technology between the medical and manufacturing industries.…”

Healing of osteotomy sites applying either piezosurgery or two conventional saw blades: a pilot study in rabbits

“…A precise and safe bone cutting technique is of the utmost importance for the preservation of vital and delicate bony structures and protection of adjacent soft tissues [3]. Therefore, recent trends have aimed at the development of novel cutting instruments to improve surgical performance and manoeuverability [4,5].…”