Total Knee Arthroplasty (TKA) in obese patients has been under rigorous scrutiny due concerns of less satisfying results and increased risk of perioperative complications. We conducted a prospective study to observe functional scores between obese and non obese patients at two years after mini-robot computer assisted TKA. Average stay, time for wound to be dry and perioperative complications were also compared.

A prospective study was conducted between February 2007 and February 2008 involving 50 patients. Two different groups of 25 each were made on the basis of body mass index (BMI). Oxford and Knee society scores were obtained at two years to observe difference in functional scores between these groups.

Rate of post operative complications or hospital stay was comparable between the two groups. Oxford and Knee society scores improved significantly in both the groups postoperatively. Obese patients had better Oxford and Knee society scores, which were not statistically significant.

There is no difference in early functional outcome and complications between obese and non obese patients after navigated TKA. Navigated TKA in obese patients help precise component placement with appropriate soft tissue balancing leading to improved results.

Computer navigated Total Knee Arthroplasty is routinely performed with gratifying results. New navigation software is now designed to help surgeons balance soft tissues in Total Knee Arthroplasty (TKA). The aim of our study was to compare functional scores at two years between two different techniques of knee balancing.

A prospective randomized control study was conducted between February 2007 and February 2008 involving 52 patients. Two different techniques of knee balancing were used namely, measured resection and gap balancing technique. Each group had 26 patients. Oxford and Knee society scores were done at two years to understand if one technique was better than other.

Oxford and Knee Society Scores improved significantly in both the groups but gap balancing technique achieved slightly better functional scores which were not significant on statistical analysis.

Computer assisted measured resection and gap balancing techniques in TKA reliably improves functional scores postoperatively. Either of the techniques if performed correctly with appropriate patient selection will have satisfactory outcomes.

The Oxford Knee Score (OKS) is a valid and reliable self-administered patient questionnaire that enables assessment of the outcome following total knee replacement (TKR). There is as yet no literature on the behavioral trends of the OKS over time. Our aim is to present a retrospective audit of the OKS for patients who have undergone TKR during the past ten years.

We retrospectively analysed 3276 OKS of patients who had a primary TKR and had been registered as part of a multi-surgeon, outcome-monitoring program at St. Helier hospital. The OKS was gathered pre-operatively and post-operatively by means of postal questionnaires at annual intervals. Patients were grouped as per their age at operation into four groups: 60, 61-70, 71- 80 and >80. A cross-sectional analysis of OKS at different time points was performed.

The numbers of OKS available for analysis were 504 pre-operatively, 589 at one-year, 512 at two-year and gradually decreasing numbers with 87 knees ten-year post-operatively. There was as expected a significant decrease (improvement) of the OKS between pre-operative and one-year post-operative period and then reached a plateau. Beyond eight years, there is a gradual rise in the score (deterioration). The younger patients (60) showed a significant increase in their average OKS between one and five-years post-operatively. However beyond five years, they followed the trend of their older counterparts. When the twelve questions in the OKS were analysed, certain components revealed greater improvement (e.g. description of knee pain and limping) than others (e.g. night pain).

The OKS is seen to plateau a year after TKR. According to the OKS the outcome of the TKR is not as good in the younger age group as compared to the older age group. Further investigation is required to ascertain the cause of this observed difference.

Publication of normal and expected outcome scores is necessary to provide a benchmark for auditing purposes following arthroplasty surgery. We have used the Oxford knee score to monitor the progress of knee replacements undertaken since 1995, the start of our review programme. 4847 Oxford assessments were analysed over an 8 year follow-up period.

The mean pre-operative Oxford knee score was 39.2, all post-operative reviews showed a significant improvement. Patients with a BMI > 40, and the under 50 age group showed early deterioration in outcome scores, returning to pre-operative levels by 5 and 7 years respectively. There was no significant difference in outcome between surgeons performing < 20 knee replacements a year and those performing > 100 / year.

The age of the patient at the time of surgery and the pre-operative body habitus have been identified as factors affecting long term outcome of total knee replacement surgery. Awareness of these factors may assist surgeons in advising patients of their expected outcomes following surgery.

Introduction: Computer assisted knee arthroplasty (CAKA) has been shown in a number of studies to result in improved post-operative alignment of prostheses. However prosthetic alignment is only one part of total knee arthroplasty surgery and outcome is likely to depend on other factors such as soft tissue balancing.

Our study compared the functional outcome following knee arthroplasty using CAKA or conventional instrumentation, and investigated whether the theoretical advantage of improved prosthesis alignment with CAKA resulted in improved functional outcome.

Materials and Methods: Data on 299 patients have been recorded to date. 139 patients have a minimum one year follow up. No patients were lost to follow up. All patients were operated on by a single surgeon at a dedicated arthroplasty centre and were allocated to one of two groups: Computer assisted navigation using a robot assisted technique (PiGalilieo, Plus Orthopaedics, Rotkreuz, Switzerland), or using conventional instrumentation. In both groups the prosthesis used was the TC-Plus Self-aligning bearing (Plus Orthopaedics).

Functional outcome was measured using the Oxford Knee Score (OKS).

A power analysis was performed with alpha of 0.05 and power of 80%. In order to detect a difference of 4 points in the OKS, 126 patients were required. This number was exceeded in our study at one year.

Results: The mean OKS at one year follow up was 24.9 (range 12 – 54, s.d. 9.8) for the CAKA group and 25.3 (range 12–49, s.d. 9.7) for the control group. There was no significant difference in functional outcome at one year between the two groups (p = 0.41).

At two years follow up the mean OKS was 25.39 (range 13 – 53, s.d. 10.3) for the CAKA group and 24.14 (range 12–43, s.d. 9.1) for the control group (p = 0.33). The results for the two year follow up group should be treated with caution as further patient numbers are awaited to obtain adequate power.

Conclusions: Although several studies show that use of CAKA results in improved prosthesis alignment, our study indicates that CAKA does not result in improved functional outcome as assessed by the patient at short term follow up. Improved prosthesis alignment is thought to result in improved long term outcome, however long term studies are necessary to show whether the known advantages of CAKA in improved prosthesis alignment results in improved patient satisfaction and increased implant survival. These further studies are important in order to justify the increased costs associated with CAKA.

Introduction: Computer assisted knee arthroplasty (CAKA) has been shown in a number of studies to result in better post-operative alignment of prostheses. However good prosthetic alignment is only one part of total knee arthroplasty surgery and outcome is likely to depend on other factors such as soft tissue balancing. Our study aimed to compare the functional outcome following knee arthroplasty using CAKA or conventional instrumentation, and to determine whether the theoretical advantage of improved prosthesis alignment with CAKA resulted in improved functional outcome.

Materials and Methods: Data on 299 patients have been recorded to date. 139 patients have a minimum one year follow up. No patients were lost to follow up All patients were operated on by a single surgeon at a dedicated arthroplasty centre and were allocated to one of two groups: Computer assisted navigation using a robot assisted technique (PiGalilieo, Plus Orthopaedics, Rotkreuz, Switzerland), or using conventional instrumentation. In both groups the prosthesis used was the TC-Plus Self-aligning bearing (Plus Orthopaedics). Functional outcome was measured using the Oxford Knee Score (OKS). There was no statistical difference in pre-operative OKS and demographic data between the two groups

A power analysis was performed with alpha of 0.05 and power of 80%. In order to detect a difference of 4 points in the OKS, 126 patients were required. This number was exceeded in our study at one year.

Results: The mean OKS at one year follow up was 24.9 (range 12–54, standard deviation (s.d) 9.8) for the CAKA group and 25.3 (range 12– 49, s.d. 9.7) for the control group. There was no significant difference in functional outcome at one year between the two groups (p = 0.41). At two years follow up the mean OKS was 25.39 (range 13–53, s.d. 10.3) for the CAKA group and 24.14 (range 12– 43, s.d. 9.1) for the control group (p = 0.33). The results for the two year follow up group should be treated with caution as further patient numbers are awaited to obtain adequate power.

Conclusion: Although several studies show that use of CAKA results in improved prosthesis alignment, our study indicates that CAKA does not result in improved functional outcome as assessed by the patient at short term follow up. Improved prosthesis alignment is thought to result in improved long term outcome, however long-term studies are necessary to show whether the known advantages of CAKA in improved prosthesis alignment results in improved patient satisfaction and increased implant survival in order to justify the increased costs associated with CAKA.

Computer navigation assistance in total knee arthroplasty (TKA) results in more consistently accurate postoperative alignment of the knee prostheses. However the medium and long term clinical outcomes of computer-navigated TKA are not widely published. Our aim was to compare patient perceived outcomes between computer navigation assisted and conventional TKA using the Oxford knee score (OKS).

We retrospectively collected data on 441 primary TKA carried out by a single surgeon in a dedicated arthroplasty centre over a period of four years. These were divided according to use of computer navigation (group A) or standard instrumentation (group B). There were no statistical differences in baseline Oxford knee score (OKS) and demographic data between the groups. 238 of these had at least a one-year follow-up with 109 in group A and 129 in group B. Two year follow-up data was available for 105 knees with 48 in group A and 57 in group B and a three year follow-up for 45 with 21 and 24 in groups A and B respectively. 12 patients had completed four year follow-up with seven and five knees in groups A and B respectively.

The mean OKS at 1-year follow up was 24.98 (range 12– 54, SD 9.34) for group A and 26.54 (range 12– 51, SD 10.18) for group B (p = 0.25). Similarly at 2-years the mean OKS was 25.40 (range 12– 53, SD 9.51) for group A and 25.56 (range 12– 46, SD 9.67) for group B (p = 0.94). The results were similar for three and four-year follow ups with p values not significant. This study thus revealed that computer assisted TKA does not appear to result in better patient satisfaction when compared to standard instrumentation at midterm follow up.

It is known from long term analysis of conventional TKA that mal-aligned implants have significantly higher failure rates beyond eight to ten years. As use of computer navigation assistance results in a less number of mal-aligned knee prostheses, we believe that these knees will have improved survivorship. The differences in OKS between the two groups should therefore be evident after eight to ten years.

Introduction: Obesity [Body Mass Index (BMI) > 30] is seen in a growing percentage of patients seeking joint replacement surgery. Recent studies have shown no clear influence of obesity on the five-year, clinical outcome of total knee replacement; except for the morbidly obese (BMI > 40). Computer navigation has shown improved consistency of prosthetic component alignment. However, this aid does significantly increase operation time.

Aims:

To compare tourniquet times of standard and computer assisted total knee arthroplasty in patients with BMI more than 30

Methods and Results: A retrospective analysis of 82, obese, total knee replacements performed by a single surgeon, at a dedicated arthroplasty centre, was undertaken. Conventional knee replacement instrumentation (Plus Orthopaedics, UK) was used in 42 cases and computer assisted navigation (Galileo- Plus Orthopaedics) in 39 cases. The patients were divided into three equal sized groups (1, 2 & 3), in chronological order. Each group comprised fourteen knees undertaken using standard surgical technique and thirteen knees using computer assisted navigation.

Group1 had average tourniquet times of 95.69 and 111.67 minutes in the standard and computer assisted groups respectively (p 0.01). Group 2 tourniquet times were 80.75 and 92.33 minutes (p 0.05). Group 3 tourniquet times were 84.5 and 87.5 minutes; these were not significantly different.

Conclusions: As the surgeon acquired experience of computer assisted navigation, his tourniquet times decreased and by the end of our study period, there was no longer any difference between the tourniquet times for conventional and computer assisted knee replacement in this subgroup of obese patients. We hypothesise that in obese patients, computer assisted navigation helps the surgeon to overcome jig alignment uncertainty and thus improves accuracy of component alignment without any significant time penalty.