The OSCAR 3 ultrasonic arthroplasty revision instrument for removing bone cement during prosthetic joint revision

Introduction

In the UK, it is estimated that 8.5 million people are affected by joint pain caused by osteoarthritis (loss of cartilage and related degradation of surrounding bone), with around 400,000 people having rheumatoid arthritis (see NICE's technology appraisal guidance on total hip replacement and resurfacing arthroplasty). People with severe or ongoing pain, joint stiffness and resultant loss of quality of life may be referred for elective joint replacement, most commonly involving the hip or knee joint, and less commonly the elbow, ankle, or shoulder joints (National Joint Registry 2013).

A variety of surgical techniques and prosthetic replacements are used in joint replacement surgery, and these may be fixed to the bone with or without the application of cement. Joint replacement surgery may involve total replacement of the joint or, alternatively, replacement of only the bone surface, known as resurfacing. The cement used for joint replacements is polymethylmethacrylate, to which an antibiotic is usually added to reduce the incidence of deep infections (National Joint Registry 2013). Cemented prostheses have the advantage of fixing the bone and prosthesis in place to allow quicker rehabilitation, and so they are preferred for older people (Rothman and Cohn 1990). The alternative option is to fix the prosthesis in place using cementless press-fit fixation. National data from 2012 shows the average age of people receiving cementless fixation was 65.2 years, whereas average age receiving cemented fixation was 73.1 years (National Joint Registry 2013). There is little evidence of superior outcomes using cementless fixation in the short- or longer-term (Abdulkarim et al. 2013).

In 2012, 76,448 hip replacements were done in the NHS in England, Wales, and Northern Ireland. Osteoarthritis was the underlying reason for 92% of hip replacements (National Joint Registry 2013), with the rest being for other indications such as fractured neck of femur due to falls (Moroni et al. 2014). Of all hip replacements in 2012, 33% were cemented, 43% were cementless, and the remainder used hybrid techniques or resurfacing procedures. Hip replacement hybrid techniques typically involve cementing of the femoral component only. In contrast, cement was used in 86% of the 90,842 knee replacements performed in 2012; most of these used high-viscosity polymethylmethacrylate cement loaded with antibiotics (National Joint Registry 2013).

Joint replacements may fail over time and need surgical revision. There were 10,040 revision hip replacements in 2012, most for aseptic loosening of the prosthesis causing unwanted prosthesis movement (44% of surgeries). Other indications included pain (25%), lysis (bone loss, 14%), dislocation or displacement (14%) and soft tissue reactions (15%), with fracture, infection, prosthesis wear, incorrect fittings or multiple causes listed as less common indications for hip revision. Cement was reapplied to 28% of femoral prostheses and 18% of acetabular prostheses. In the same period, there was 6009 knee revision procedures performed, again with aseptic loosening being the most common indication (48%) (National Joint Registry 2013).

An important element in the success of surgical revision of the hip, knee or other large joints is the safe and efficient removal of cement, where present, from the host bone (Goldberg et al. 2007). Cement removal may be needed to detach well-fixed prostheses, and to allow for the insertion of longer or differently shaped prostheses. Traditional techniques for cement removal have included the use of drills, burrs, curettes and osteotomes. However, this mechanical removal can be difficult and time-consuming and carries the risk of bone perforation. To overcome some of these problems, the use of ultrasonic cement removal has been developed and this is reported to have the advantages of reducing surgery time and surgical complications (Goldberg et al. 2007).