Focal resurfacing implants to treat articular cartilage damage in the knee

2.1 Cartilage covers the end of the bones comprising the knee joint. There are 2 types of cartilage in the knee – articular (or chondral) and meniscal. Damage because of injury or disease to a focal area of articular cartilage, particularly in the main weightbearing areas, can cause pain, stiffness and reduced mobility. Cartilage tissue has very limited self-healing potential and, if left untreated, cartilage damage can progress to osteoarthritis.

2.2 Treatment for focal articular cartilage damage typically involves arthroplasty or biological treatment. Types of arthroplasty include total, bicompartmental, unicompartmental and patellofemoral. Types of biological treatment include microfracture, osteochondral autograft transfer system and autologous chondrocyte implantation.

2.3 Focal articular resurfacing is aimed at people for whom biological treatments and arthroplasty may not be suitable because of age or other factors.

2.4 Before surgery, the articular cartilage damage is assessed using a preplanned MRI, an arthroscopy or both. Then, either the implant is customised to fit the damaged area, or an implant is selected from a catalogue to closely match the damaged area. Various implant brands, designs and materials are used for the procedure. The procedure is done under regional (spinal) or general anaesthesia. An incision is made to access the damage site. The damaged area is prepared by removing the damaged bone and cartilage, and drilling a hole for the stem of the implant. The implant is then press-fitted into the damaged area with or without bone cement. The surface of the implant is slightly recessed below the surrounding articular cartilage.

2.5 Rehabilitation after surgery depends on the person and implant. It typically includes either an immediate (as tolerated) or gradual return to full weight bearing and range of motion.

2.6 The aim of this procedure is to alleviate pain, allow immediate weight bearing, preserve physiological joint function, slow progression to osteoarthritis, and reduce or delay the need for arthroplasty.