The aim of this study was to examine the progression of osteolytic lesions following liner exchange surgery and relate this to the size of the lesion prior to surgery, and whether the defect underwent curettage and bone grafting during surgery.

Six patients with well-fixed Harris-Galante-1 acetabular components underwent liner exchange surgery for excessive polyethylene wear and osteolysis. The mean interval from primary arthroplasty to revision was 14 years (range 11–17 years). All patients underwent a CT scan pre-operatively to identify the location and size of the osteolytic lesions and during surgery, accessible lesions were curetted and bone grafted. One patient had recurrent dislocations and the acetabular component was revised one year following liner exchange surgery. The remaining five patients had CT scans taken at a mean of five months (range 3–5 months) and 5 years (range 3.4–8.2 years) following surgery. Osteolytic lesion volume with or without bone grafting was measured.

Of the 19 osteolytic lesions detected pre-operatively, the first post-operative CT scan showed that four lesions were fully bone-grafted, ten lesions were partially bone-grafted and five lesions had no bone grafting during surgery. At a minimum of three years following surgery, all fully bone-grafted lesions remained full of bone- graft. Of the ten partially bone-grafted lesions, the osteolytic non-grafted zone decreased in volume in five lesions and five lesions remained unchanged. Of the five osteolytic lesions with no bone grafting, one lesion increased in volume, one lesion decreased in volume and three lesions remained unchanged. No new lesions were detected in any of the hips.

These preliminary results suggest that liner exchange surgery is effective in treating periacetabular osteolysis. Although bone grafting appears to aid in restoring bone stock, it is not essential in halting the progression of osteolysis, which likely results from the ongoing production of polyethylene particles in the joint.

Sensitive and accurate measures of osteolysis around TKR are needed to enhance clinical management and assist in planning revision surgery. Therefore, our aim was to examine, in a cadaver model of osteolysis around TKR, the sensitivity of detection and the accuracy of measuring osteolysis using Xray, CT and MRI.

Fifty-four simulated osteolytic lesions were created around six cadaver knees implanted with either a cemented or cementless TKR. Twenty-four lesions were created in the femur and thirty in the tibia ranging in size from 0.7 cm3 to 14 cm3. Standard anteroposterior and lateral fluoroscopically guided radiographs, CT and MRI scans with metal reduction protocols were taken of the knees prior to the creation of lesions and at every stage as the lesion sizes were enlarged. The location, number and size of the lesions from images obtained by each method were recorded.

The sensitivity of osteolytic lesion detection was 44% for plain radiographs, 92% for CT and 94% for MRI. On plain radiographs, 54% of lesions in the femur and 37% of lesions in the tibia were detected. None of the six posterior lesions created in the tibia were detected on the AP radiographs; however, three of these six lesions were detected on the lateral radiographs. CT was able to detect lesions of all sizes, except for four lesions in the posterior tibia (mean volume of 1.2 cm3, range 1.06–1.47 cm3). Likewise, MRI was very sensitive in detecting lesions of all sizes, with the exception of three lesions, two of which were in the femur and one was in the medial condyle of the tibia (mean volume of 1.9 cm3, range 1.09–3.14 cm3). Notably, all six posterior tibial lesions, which could not be detected using AP radiographs, were detected by MRI.

This study demonstrates the high sensitivity of both CT and MRI (which uses no ionising radiation) to detect simulated knee osteolysis and can therefore be used to detect and monitor progression of osteolysis around TKR. The study also shows the limitations of plain radiographs to assess osteolysis.

This study aimed to compare the early clinical results and stem subsidence between three consecutive series of revision hip replacement cases with femoral impaction bone grafting to evaluate the effects of developments in technique. In the original series 1 (n=23), bone graft was irradiated at 25kG. I n series 2 (n=12) non-irradiated double washed graft and long stems were used as required.

In series 3 (n=21) modular tamps were used. Sensitive radiographic analysis techniques, EBRA and RSA, were used to measure stem subsidence. Major stem re-revision was required in five hips in series one, one hip in series two and no hips in series three. Two periprosthetic fractures occurred in series one. There was a statistically significant reduction in stem subsidence at the cement-bone interface at 12 months between series one and series two and three (p<0.05). In series three there was negligible stem subsidence at the cement-bone interface.

Technique developments in femoral impaction grafting, including the use of modular tamps designed to simply the procedure, yields excellent early clinical and radiographic results. Using RSA, we have shown that the fixation of the stems in bone is comparable to that achieved in primary hip replacement.