Study of an all polyethylene tibial component
Research type
Research Study
Full title
A prospective study of an all polyethylene tibial component used in total knee arthroplasty surgery
IRAS ID
181031
Contact name
Alistair M Ewen
Contact email
Sponsor organisation
National Waiting Times Centre
Clinicaltrials.gov Identifier
Duration of Study in the UK
1 years, 10 months, 29 days
Research summary
Summary of Research
In this prospective single cohort investigation, outcomes of the Columbus all polyethylene tibia (Aesculap AG, Tuttlingen, Germany) used in total knee arthroplasty (TKA) will be determine around 18 months post-operatively.
In the majority of TKA operations, a metal tibial tray is attached to the shin bone (tibia) and a plastic (high density polyethylene) bearing is attached on to it. These ‘metal backed’ tibial components are expensive. A lower cost alternative does away with the high cost metal tray by using a single all polyethylene piece which is attached directly to the shin bone.
Consecutive TKA patients under the care of two consultant orthopaedic surgeons at the Golden Jubilee National Hospital who meet the inclusion/exclusion criteria will be recruited to the study and will be given the all polyethylene tibia. Recruitment will continue until 30 participants have had the all polyethylene tibia implanted.
Participants will return for their standard post-operative follow-up appointments (6 weeks and 1 year post-operatively). At the 6 week post-operative appointment they will have a bone mineral density (BMD) scan in addition to a plain radiograph of the whole leg. They will also have an additional appointment at the hospital around 18 months post-operatively specifically for a second BMD scan. Neither of the BMD scans are part of standard care.
The data which will be analysed will be, the results of the bone scans, computer generated data about the range of movement (RoM) and alignment of the operated knee collected as part of the operation, the RoM, clinical outcome and satisfaction data collected at the pre-operative assessment and post-operative follow-ups, pre- and post-operative x-rays, complications, survivorship and surgeon experience of using the all polyethylene tibia. These data will be investigated to determine if the all polyethylene tibia has satisfactory outcomes with no adverse effects.
Summary of Results
What was this study about?
This study tested a simpler, less expensive type of knee replacement to see if it works as well as the standard version. Most knee replacements today use a metal component with a plastic top, which is more costly. This study examined whether an all-plastic component could deliver equally good results when combined with modern computer-guided surgery.
Why is this important?
With people living longer and knee replacements becoming more common, the NHS performed over 7,000 knee replacement procedures in Scotland in 2017—more than double the number in 2001. Finding high-quality, cost-effective options helps the NHS provide excellent care to more patients. In the past, all-plastic components sometimes failed due to poor positioning, but computer navigation technology may have addressed this issue.
What did the researchers do?
Between 2016 and 2017, 27 patients aged 65 and older received knee replacements using an all-plastic component positioned with computer navigation. Researchers measured bone density around the artificial knee at 6 weeks and 18 months after surgery, assessed knee function and alignment, tracked patient satisfaction, and monitored for any complications. All patients had a BMI under 37.5 and good bone quality.
What were the results?
Bone Health: The bone around the artificial knee remained healthy and stable over 18 months with no significant bone loss, indicating the implant was well-fixed and secure.
Function and Satisfaction: Patients achieved excellent outcomes:Average knee bending of 102.5 degrees (similar to standard replacements) Good leg alignment Significant improvement in knee function scores Nearly 80% of patients satisfied or very satisfied with results
Safety: No implants failed or required replacement, and no implant-related complications occurred during the study period. Surgery time was comparable to standard procedures.
Consistency: Results were similar across different patient groups (men vs. women, various body weights within study limits).
Surgeon Experience
Both surgeons, despite having no prior experience with this specific all-plastic component, were satisfied with its performance. Computer navigation successfully helped them position and balance the knee without needing the adjustable features of metal-backed components. Early technical challenges improved quickly with experience.
What does this mean?
This study demonstrates that for carefully selected patients—those aged 65 and over with BMI under 37.5, good bone quality, and lower activity levels—all-plastic knee components work as well as more expensive metal-backed versions when combined with computer-guided surgery.
The potential benefits include lower costs for the NHS (allowing more patients to receive treatment), good function and patient satisfaction, stable implants without bone loss, and no increased complication risk.
Important considerations
Results are based on 18 months of follow-up; longer-term studies would provide additional confidence. The study included only patients meeting specific criteria, and computer navigation was essential to achieving these good results. Patients considering knee replacement should discuss all available options with their orthopaedic surgeon.REC name
East of Scotland Research Ethics Service REC 1
REC reference
15/ES/0187
Date of REC Opinion
3 Dec 2015
REC opinion
Further Information Favourable Opinion