We performed a randomised prospective trial to compare a cemented unipolar prosthesis (Thompson) with a cemented bipolar prosthesis (Monk) in the treatment of displaced intracapsular fractures of the hip in patients over 80 years of age. Patients with a mental test score of less than 5/13 were excluded but the mortality was still about 30% at one year in both groups. We therefore feel that subjective criteria such as the level of pain and the return to the preinjury state are of paramount importance.

Two years after operation there was no statistical difference between the rate of complications in the two groups. After adjusting for confounding factors such as differences in the level of function before injury between the groups, the degree of return to the preinjury state was significantly greater (p = 0.04) when using the unipolar prosthesis, which is one-quarter of the price of the bipolar.

We cannot therefore justify the use of an expensive bipolar prosthesis in patients over 80 years of age.

Three radiological methods are commonly used to assess the outcome of total hip replacement (THR). They aim to record the appearance of lucent areas and migration of the prosthesis in a reproducible manner. Two of them were designed to monitor the implant through time and one to grade the quality of cementing. We have measured the level of inter- and intraobserver agreement in all three systems.

We randomised 30 patients to receive either finger packing or retrograde gun cementing during Charnley hip replacements. The postoperative departmental radiographs were evaluated in a blinded study by two orthopaedic trainees, two consultants and two experts in THR. The trainees and consultants repeated the exercise at least two weeks later. We used the unweighted kappa statistic to establish the levels of agreement.

In general, intraobserver agreement was moderate but interobserver agreement was poor, with levels similar to or less than those expected by chance. Our results indicate that such systems cannot provide reliable data from centres in different parts of the world, with various levels of surgeon evaluating radiographs at differing time intervals. We discuss the problem and suggest some methods of improvement.

Despite the use of ultraclean air, there are still cases of infection in total joint arthroplasty. One possible route by which bacteria may enter the wound is indirectly by contamination of instruments during skin preparation and draping.

We found that bacterial air counts were 4.4 times higher during preparation and draping for hip or knee arthroplasty using an unscrubbed, ungowned leg holder than during the operation itself. With the leg holder scrubbed and gowned during preparation and draping, the air counts were reduced but were still 2.4 fold greater than intraoperatively. On some occasions, the air counts during preparation and draping exceeded the standards for ultraclean air irrespective of the attire of the leg holder.

We recommend that the leg is held by a scrubbed and gowned member of the team. More importantly, we consider that instrument packs should be opened only after skin preparation and draping have been completed.