The McMinn Centre - Excellence in Hips & Knees Hip Resurfacing
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Alternative to Hip Replacement
Welcome to The McMinn Centre, specialising in bone-conserving hip and knee procedures for young & active patients
Lectures
Research Lectures History
Northern Lights Debate ASR vs BHR
Metal ions and Wear Rates in the BHR
Mini Incision Surgery
Dislocation Rates
Systemic Metal Exposure
What is the BMHR?
Carbides - Myth or Fact
10-Year survival of Double Heat-treated Hip Resurfacings from 1996
Sir Robert Jones Lecture
BOA September 2010
BOA September 2010
The Birmingham Hip Resurfacing and Other Options – The 15 Year Results of the First 1000 BHRs
Design of knee replacement- Can we approach normal knee function? Derek McMinn 2014
 'Metal-on-Polyethyene in Hip Resurfacing' - Derek McMinn, Ghent, May 2014
‘Race for Non MoM Resurfacing - Can we avoid another ASR?’ - Derek McMinn, Ghent May 2014
'Can We Classify Implants By Risk? – Resurfacing' - Derek McMinn, London September 2014
'Movement Patterns of the Knee Relevant to TKR' - Derek McMinn, London Knee Meeting, October 2014
Compromises in Knee Replacement Design - Derek McMinn, London Knee Meeting. October 2014
Hip Resurfacing - Does It Have A Future?
Why are the Functional Results
 of TKR so Poor?
Northern Lights Debate ASR vs BHR
Northern Lights Debate ASR vs BHR
Update on Hip Resurfacing' - Derek McMinn, December 2016
Causes of Failure with Hip Resurfacing
enquiries@mcminncentre.co.uk
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Design of knee replacement- Can we approach normal knee function? Derek McMinn 2014

In this talk, presented May 2014 at the 6th Advanced Hip Resurfacing Course in Ghent, Mr Derek McMinn MD FRCS looks at knee replacement design and how that design influences joint function.
 
John Goodfellow and John O'Connor came to the conclusion that the position of the femur on the tibia is indeterminate whereas Michael Freeman found the opposite by precisely defining said positioning. Mr McMinn shows the medial, lateral and central rotation movement of the femur using fluoroscopy and a cadaveric knee. The natural femoral condyles of the knee are spiral, therefore inducing a side to side translatory movement during flexion and extension. A study shows that on twenty two cadaver knees during flexion, the femur translates laterally approximately 5mm on the tibia. This is vital for the patella as maltracking will occur if the femur and the patella groove do not translate laterally in flexion.
 
Mr McMinn looks at the flexion statistics of the PCL Retaining Total Knee Replacement. A study shows that in a group of 150 patients, seventy two percent of knees had impingement between the back of the femur and the back of the tibial polyethylene. The mean pre-operative range of flexion was 105° and post-operative was 105.9°. For every 2mm decrease in posterior condylar offset, the maximum flexion was reduced by 12.2°.
 
The major disadvantage of the Posterior Stabilised Total Knee Replacement is gross anterior to posterior mid-flexion instability. The Medial Rotation Total Knee Replacement is good in mid-flexion but not in high flexion where the femur slides forward on the tibia leading to impingement. In high flexion, the Birmingham Knee Replacement (BKR) brings the femur to the back of the tibia. The BKR has spiral femoral condyles, matching the natural kinematics of the knee. The combined static and dynamic effect is 10mm, laterally translating the femur in flexion and the opposite in extension.
 
Results for seventy nine BKRs (in seventy two patients) show the highest Oxford Knee Score of 12 for follow up – excluding ten patients whose inferior scores were due to other pathologies. Knee flexion results show a 21° post-operative improvement in range of flexion. Maximum walking speed is slower for patients with a standard knee replacement (6.5km/h) and the loading through the replaced side does not match the normal side. Comparatively, patients with a BKR have a faster maximum walking speed of 11km/h and the loading closely matches that of the normal knee.
 
National Joint Register PROMs data shows that nearly fifteen percent of Total Hip Replacement and nearly thirty percent of Total Knee Replacement patients are not much better since their operation. There is a lot of improvement needed in the design of knee replacements in order to achieve better function for knee replacement patients.

 

© The McMinn Centre - Mr Derek McMinn MD FRCS Hip Resurfacing Birmingham UK