Critics of Unicompartmental knee replacement (UKR) highlight poor survivorship in national joint registries and argue that revision to Total Knee Replacement (TKR) is technically difficult with inferior function and survivorship compared to primary TKR.

We prospectively reviewed outcomes of UKRs in our institution undergoing early revision to a TKR, comparing conventional revisions to those performed using computer navigation. 20 cases were identified, 7 conventional and 13 navigated. 13 were male and 7 female, mean age at primary UKR was 63.6 years (range: 47–81).

Mean follow up time after revision was 5.2 years (2–9.5). Mean surgical time was 152 mins in conventional revisions and 163 mins for navigated. 43% of conventional cases required revision stems or augments, compared to 15% of conventional cases. Mean Oxford Knee Scores for revised knees were 32.8 in the conventional group and 34.64 in the navigated group, compared to 30.02 in the national joint registry. This compares to a mean Oxford score of 37.16 for primary TKRs in the registry. One of the conventional revisions required a further revision of the tibial component for loosening. This equates to a 95% suvivorship at mean 5 year follow up, or 1.10 revisions per 100 component years. Joint registry data had 1.97 revisions per 100 component years for UKR to TKR revisions, and 0.48 for primary TKRs.

Our results are significantly improved compared to other published series of UKR revisions to TKRs. Only one other series has reported outcomes of these revisions using navigation. Despite small numbers, our results suggest that navigation makes revisions of UKRs more straightforward with similar surgical times. Fewer revision components were required with navigation and functional scores were marginally improved.

Aim: The study was conducted to evaluate differences between simultaneous and sequential cementing of the tibial and femoral components in total knee joint replacement in relation to final component alignment. Our hypothesis was that cementing the components sequentially increases accuracy of the final position.

Method: This was a prospective and randomised study, performed using a computer navigation system as the evaluation technique to determine the accuracy of implant positioning. All knee replacements (Scorpio, Stryker) were implanted with the assistance of computer navigation. The patients were divided into two groups of 20 patients each. The first group had implants cemented simultaneously where the tibial and femoral components were implanted with a single mix of cement and then pressurized by extending the leg. The second group of patients had the tibial component inserted with the first mix of cement and then impacted. Then the femoral component was inserted using a second mix of cement. Computer navigation was used to measure varus/ valgus cut of the femur, varus/ valgus cut of the tibia, and sagital slope of the tibia. Measurements were made with the components in place, both before cementing and then after cement cure.

Results: Our results show a statistically significant improvement in accuracy of femoral varus/ valgus alignment using the sequential cementing technique.

Introduction: We present our early results using the Stryker navigated knee system, since March 2003. There have been several papers showing an improvement in alignment of prostheses using navigation but few series have mentioned the problems of introducing this new technology.

Method: 214 consecutive operations were audited retrospectively from operation notes, discharge summaries and clinic notes.

Results: 11 surgeons performed 214 operations on 196 patients. 205 operations were primary knee joint replacements and 9 revisions. Average operation time was 149 minutes. 96% had an excellent outcome (pain free with a good range of motion), 2.6% had a moderate outcome and 1.4% had a poor outcome. 17 patients had superficial wound infections; 4 patients required an MUA for stiffness (with a good outcome); 3 DVTs (all below knee); 1 acute and 3 delayed haemarthroses; 1 temporarily unstable knee; 5 suffered prolonged pain, 1 peri-prosthetic fracture due to anterior notching of the femur requiring revision and there was 1 quads tendon rupture. There were 4 procedures abandoned, 2 because the femoral pin was unstable in osteoporotic bone and because of 2 software errors. Average range of motion was 0–110°. There was one deep infection following pyelonephritis. Average follow up has so far been 20.6 (2–104) weeks.

Conclusion: We have found that our results compare favourably with conventional techniques. We found it particularly useful for revision surgery and those patients who had intramedullary devices for previous fractures of the femur where conventional jigs could not be used.

The study was conducted to investigate differences between simultaneous and sequential cementing of the tibial and femoral components in total knee joint replacements. Our hypothesis was that cementing the components sequentially increases accuracy of the final position.

This was a prospective and randomized study, performed using a computer navigation system as the evaluation technique to determine the accuracy of implant positioning. All knee replacements (Scorpio, Stryker) were implanted using navigation technique.

The patients were divided in two groups. The first group had implants cemented simultaneously where the tibial and femoral components were implanted with a single mix of cement and then pressurized by extending the leg.

The second group of patients had the tibial component inserted with the first mix of cement and then impacted. The cement was allowed to set before proceeding with insertion of the femoral component using a second mix of cement.

The computer navigation system was utilized for bone cuts. It was then used to measure 3 sets of angles. The first set was varus/valgus cut of the femur, varus/valgus cut of the tibia and posterior slope of the tibia. The second set of measurements were the same angles, this time of the position of the prosthetic components before cementing, and the third set after cementing.

Our interim results show just a small difference between the two techniques.

It does not appear there is substantial difference in positioning of the implants between these two different techniques.

Introduction and Aims: To evaluate the long-term results of an operation which does not involve instrumentation or fusion and which leaves the midline structures intact.

Method: A retrospective clinical and radiological review of consecutive patients.

Results: One hundred and sixty patients (87 females and 73 males) with a mean age at operation of 68 (range 40–90); the majority of patients (79%) had either a one or two level bilateral decompression. The most common level decompressed was the L4/5 level (91%). The mean post-operative follow-up was 22 months.

Summary of background data: spondylosis, commonly involving a degenerative listhesis, is the most common cause of stenosis in the lumbar spine. The symptoms arise from root compromise of the stenotic level and surgery offers the only permanent cure. To date, the standard procedure remains a laminectomy with fixation and fusion in the presence of possible instability. A laminectomy, however, destabilises the spine and the instrumented fusion makes it a much bigger operation in patients often not best placed to cope with it. There has been, therefore, a need for an effective operation that does not compromise spinal stability.

Conclusion: At six weeks post-operation, 141 patients (85%) reported relief of leg pain and this rose to 90% at six months. One hundred and fifty-three patients (96%) reported an increase in their walking distance. Of those patients who also presented with back pain pre-operatively, 79% reported an improvement. There were no significant post-operative complications. The results were sustained at follow-up.

The operation of limited segmental decompression for degenerative lumbar spinal stenosis has been found to be effective, safe, and providing good long-term results, without compromising the existing spinal stability. Appropriate patient selection and attention to operative technique are of paramount importance.