The case for removing the subchondral bone plate in preparation of the acetabulum

Positive effect of removal of subchondral bone plate for cemented acetabular component fixation in total hip arthroplasty: a randomised RSA study with ten-year follow-up

We hypothesised that the removal of the subchondral bone plate (SCBP) for cemented acetabular component fixation in total hip arthroplasty (THA) offers advantages over retention by improving the cement-bone interface, without jeopardising implant stability. We have previously published two-year follow-up data of a randomised controlled trial (RCT), in which 50 patients with primary osteoarthritis were randomised to either retention or removal of the SCBP. The mean age of the retention group (n = 25, 13 males) was 70.0 years (sd 6.8). The mean age in the removal group (n = 25, 16 males) was 70.3 years (sd 7.9). Now we have followed up the patients at six (retention group, n = 21; removal group, n = 20) and ten years (retention group: n = 17, removal group: n = 18), administering clinical outcome questionnaires and radiostereometric analysis (RSA), and determining the presence of radiolucent lines (RLLs) on conventional radiographs. RSA demonstrated similar translation and rotation patterns up to six years. Between six and ten years, proximal acetabular component migration and changes of inclination were larger in the retention group, although the mean differences did not reach statistical significance. Differences in migration were driven by two patients in the SCBP retention group with extensive migration versus none in the SCBP removal group. The significant difference (p < 0.001) in the development of radiolucent lines in the retention group, previously observed at two years, increased even further during the course of follow-up (p < 0.001). While recognising SCBP removal is a more demanding technique, we conclude that, wherever possible, the SCBP should be removed to improve the cement-bone interface in order to maximise acetabular component stability and longevity.

Long-term clinical results of Charnley total hip arthroplasty using a matte satin-finished stem: a 30-year average follow-up study

BACKGROUND

Although 50 years have passed since Charnley started performing total hip arthroplasties, there are relatively few patient studies with a follow-up period of over 30 years. We studied radiograms of patients who had undergone Charnley total hip arthroplasty between 1975 and 1981 and evaluated the results at 26-35 years (mean 30.5 years) after the operation.

METHODS

The operations were performed in 87 joints of 82 patients (26 males and 56 females) aged 26-81 years (mean age 56 years) at the time of surgery. A monoblock-type Charnley stem with a 22-mm head was used in all patients. The stem had a matte satin surface finish and a flange or round-back shoulder. The socket was made of ultra-high-density polyethylene without a flange. All operations were performed by one surgeon using the original Charnley method in all patients, excluding the first five.

RESULTS

Thirty years after the operation, 48 patients have died, 5 had an infection, 9 were lost to follow-up, and 20 patients with 24 joints are still alive. In 77 patients (82 joints), after excluding the 5 with infection, the socket and stem survival rates were 54 and 75% at 30 years after the operation when radiographic loosening or revision surgery was defined as the end point. With revision surgery as the end point, the rates were 68 and 82%, respectively.

CONCLUSIONS

These results were as favorable as those with surgical techniques (including the first-generation cement technique) and implants in the early period. Although new techniques and implants have since been introduced, their long-term results should exceed those in this study. The results of this study should provide a valuable index with which to compare the long-term studies of current total hip arthroplasty.