Review article: Polyethylene wear and osteolysis in total hip arthroplasty

Journal of Orthopaedic Surgery, Jun 2001 by Zhu, Y H, Chiu, K Y, Tang, W M

Entirely different combinations of articulating materials which eliminate polyethylene altogether have been used, such as ceramic-on-ceramic, metal-- on-metal, etc. Ceramic-on-ceramic implants may become common in the future of total hip arthroplasty because of their resistance to wear and following inapparent osteolysis. The clinical literature has revealed no apparent osteolytic response regarding all-- ceramic articulations of total hip replacement.33 Metal-- on-metal articulation appears to be effective in reducing wear and loosening when compared with metal-on-polyethylene in a four to seven-year follow-- up.12 However, metal-on-metal bearings generate systematic release of cobalt that can be detected in serum.6

Apart from primary bearing surface wear and secondary nonbearing surface wear, three-body wear, which refers to motion between two primary bearing surfaces with third-body particles trapped between, is also an important wear mode.25 Since fragments of cement, bone, metal or polyethylene particles are included, surgeons should remove all the particulates produced during the operation. Therefore, irrigating the joint space appears to lower the chance of polyethylene wear.

Secondly, it is important to prevent debris from gaining access to the bone-implant interface. The presence of cement or circumferential coatings may retard the distal migration of particles. Cementing a femoral stem into the medullary cavity with third generation cement techniques will diminish the effective joint space and seal the entrance to the femoral component. Also, circumferential porous coating in cementless femoral prosthesis aims at creating a seal at the proximal femur since a bioactive surface with osseointegration has an efficient sealing effect.30 The same phenomenon can be postulated on the acetabular side. Prostheses that have a non-circumferential porous surface allow the formation of fibrous channels through which particulate debris may pass. The integrity of such a barrier may depend to some extent on the design of the component.

Thirdly, one must deal with the cellular response which may result in osteolysis. The aim is to reduce the lysis of bone caused by the activity of osteoclasts. The bone lysis occurring in tissue culture secondary to the presence of the tissue membrane can be partially inhibited by indomethacin.13 Bisphosphonate was originally used successfully for conditions such as osteoporosis and Paget's disease that share the common pathway of bone resorption by osteoclastic activity It has also been shown clinically to increase the bone mineral density in osteoporosis in postmenopausal women. In vivo study in an animal model of total hip arthroplasty has been available to show that bisphosphonate significantly reduces osteolysis which was induced in an uncemented system with polyethylene and alloy particles.11,34

TREATMENT

In acetabular and femoral component osteolysis, if the patient is asymptomatic, non-surgical treatment such as activity modification can be initiated, and regular follow-up is essential to determine the rate of progression. For symptomatic cases, non-surgical options may include activity modification, limited weightbearing with walking aids, NSAIDs, and followup on a frequent basis every three months. Bisphosphonate has proved to be able to reduce osteolysis in animal experiments. However, there are few reports on the clinical use of bisphosphonate.