Aims

This study reports on the medium- to long-term implant survivorship and patient-reported outcomes for the Avon patellofemoral joint (PFJ) arthroplasty.

Patients with severe knee instability remain a surgical challenge. Furthermore, in the presence of extensive bone loss, constrained condylar implants may be unsuitable.

Hinged knee replacements have served an important role in the management of such complex knee pathologies.

A combined prospective and retrospective study of 138 consecutive hinge knee arthroplasties (42 primary and 96 revisions) of 8 different models performed in our institution between 2004 and 2010 at a mean follow up of 4.2years.

Outcomes were reviewed and knee scores preoperatively and postoperatively at 1, 2 and 5 years using the American knee scoring system.

The mean preoperative American knee score of 31 improved to 87 postoperatively.

Complication rate was 19%, 15% of which required re-revisions for: loosening (4%), Infection (4%), periprosthetic fracture (3%), Implant fracture (2%), Component disassembly (1%) and dislocation (1%). Overall implant failure rate was 9% and implant survivorship was greater than 80% at 4 years.

In our study, hinge prostheses provided good stability and symptom relief with a lower complication rate compared to some previous studies.

In addition, we believe hinge prostheses can also serve as reasonable alternatives to amputation and arthrodesis in many complex knees cases.

We identified 148 patients who had undergone a revision total knee replacement using a single implant system between 1990 and 2000. Of these 18 patients had died, six had developed a peri-prosthetic fracture and ten had incomplete records or radiographs. This left 114 with prospectively-collected radiographs and Bristol knee scores available for study. The height of the joint line before and after revision total knee replacement was measured and classified as either restored to within 5 mm of the pre-operative height or elevated if it was positioned more than 5 mm above the pre-operative height. The joint line was elevated in 41 knees (36%) and restored in 73 (64%).

Revision surgery significantly improved the mean Bristol knee score from 41.1 (sd 15.9) pre-operatively to 80.5 (sd 15) post-operatively (p < 0.001). At one year post-operatively both the total Bristol knee score and its functional component were significantly better in the restored group than in the elevated group (p < 0.01). Overall, revision from a unicondylar knee replacement required less use of bone graft, fewer component augments, restored the joint line more often and gave a significantly better total Bristol knee score (p < 0.02) and functional score (p < 0.01) than revision from total knee replacement.

Our findings show that restoration of the joint line at revision total knee replacement gives a significantly better result than leaving it unrestored by more than 5 mm. We recommend the greater use of distal femoral augments to help to achieve this goal.

Aim: To assess the results of aseptic and aseptic cases using the PFC/TC3 system, and to correlate this with the restoration of joint line height.

Method: 148 patients underwent revision TKR using the PFC/TC3 system. No re-revision cases were included in this series. Data was prospectively collected (using the Bristol Knee Score) pre-operatively and at a mean of 4.2 years post-revision. 31 revisions were for infection and 53 revisions were for aseptic loosening. Revision for infection was done as a two-stage procedure and aseptic as a single operation. Measurements of the joint line height were made pre and post-operatively using Figgie’s method. The cases were divided into 3 groups on the basis of joint line restoration:

Lowered by more than 5 mm

Results: The mean pre-op total score for the infection group was 35/100 and 40/100 for the aseptic loosening group. The total score post-operatively was 67 for the infection group and 73 for the aseptic loosening group. The joint line was restored in 50% of infected cases and in 60% of aseptic loosening cases.

Conclusion: although the overall results were slightly less satisfactory for the infected revision group, there was no significant difference between the two groups either in total BKS scores or in reproduction of the joint line. The average outcome was much less good than for primary TKR.

Introduction: Correct prosthesis alignment and joint line reproduction in total knee replacement (TKR) is vital for a successful clinical outcome. It is acknowledged that the ideal coronal alignment of the knee following TKR should be between 4–10 degrees of valgus. A neutral or varus knee is associated with a higher failure rate. Previous studies have shown that ideal alignment is achieved in only around two-thirds of cases.

Joint line elevation > 8mm has been associated with inferior clinical outcome, and depression associated with retropatellar pain and increased risk of patella subluxation.

Recently, modifications have been made to the Kine-max-Plus Total Knee System instrumentation, theoretically providing better internal fixation to prevent a varus cut and a 12 mm measured resection from the “normal” tibial plateau. This study aims to examine whether these changes result in an improvement in alignment, and a more reliable restoration of joint line.

Materials and Methods: Two consecutive series, each of 75 patients who had undergone TKR using either the old (Group A) or the new (Group B) instrumentation were included in the study. Antero-posterior and lateral preoperative and postoperative knee radiographs were assessed using the American knee society radiographic analysis for prosthesis postionoing by 2 independent observers. The Tibial and Femoral Component Angles in the coronal plane (cTCA and cFCA) and in the sagittal plane (sTCA and sFCA) were measured, as was the change in joint line height.

Conclusion: Our results suggest that use of the new instrumentation is associated with better restoration of joint line, and is more effective in preventing implantation of the tibial component in varus. These figures relating to a modern instrumentation system provide a yardstick against which computer assisted and robotic surgery can be judged. Long-term follow-up will be required to assess the clinical significance of these results.

Purpose: This study analyses the kneeling ability of patients following Unicompartmental knee replacement (UKR), Patellofemoral replacement (PFR) and Total knee replacement (TKR).

Method: Data was prospectively collected on 272 knees (254 patients) that had undergone various forms of arthroplasty procedures for osteoarthritis of the knee. All patients completed the Oxford Knee Questionnaire preoperatively and 1 year postoperatively, thus graded their kneeling ability into one of 5 categories. Absolute values and change following arthroplasty were recorded. In addition the reported kneeling ability of 75 patients was checked by clinical examination.

Results: Preoperatively only 2% of all patients could kneel with PFR group being more able than the others (UKR 0%, TKR 0% and PFR 6%). In all groups the kneeling ability was better one year following replacement than preoperatively (23% of UKR, 18% of TKR and 9% of PFR) being able to kneel with little or no difficulty.

Conclusions: No form of arthroplasty used resulted in good kneeling ability, though this function was always improved particularly by UKR. Good range of movement and younger age appeared to correlate with better kneeling ability but many patients thought they had been told not to kneel and reported less ability than they demonstrated on examination. Instruction to avoid kneeling seems unnecessary.