ISSN 0972-978X 

  About COAA








Do Rotating Platform LCS Knees Continue To Rotate In Vivo?

* Joby John, Jacob Varughese

*Amrita Institute of Medical Sciences, Kochi, India. 

Address for Correspondence

Joby John,
Amrita Institute of Medical Sciences, Kochi, India. 


Background: Tricompartmental knee replacement has been shown to produce good function and have a good survivorship. The limiting factor in the function of knee replacements is polyethylene wear and subsequent loosening at the bone prosthesis interface. Mobile bearing prosthesis were developed to decouple the translational and rotational motions, thus decreasing the wear. This would be effective only if  the bearings continue to remain mobile invivo.
Methods: 10 LCS knees implanted in the period beginning 2000 with at least 1 year follow-up were examined fluoroscopically to determine if the rotating platform was indeed rotating in vivo. 
Results: All the knees examined were found to have polyethylene bearings which were still mobile.
Conclusions: Rotating platforms in LCS knees continue to rotate at early follow-up. Further studies have to be conducted to examine whether these rotating platforms are still mobile at further longer follow-up.

J.Orthopaedics 2006;3(2)e6


Replacement arthroplasty of the knee is a successful procedure. The relief of pain and the restoration of function can be dramatic, and the rate of survival of the implants is long enough to satisfy most patients requiring knee replacement1.The general consensus is that total condylar (tricompartmental) knee arthroplasty substantially changes the kinematic profile of the knee2. This may be due to several factors including the differences between the geometry of the normal articular surface of the knee and the replacement prosthesis, loss of the anterior and/or posterior cruciate ligaments, and altered neuromuscular patterns due to preexisting disease. All knee replacements are subject to problems of polyethylene wear. Rotating platform knees were designed and implanted from 1978 onwards to minimize the wear and loosening problems of earlier designs3. Increasing the surface congruity during major load bearing activities was the mechanical concept for the New Jersey Low Contact Stress (LCS) total knee system. Such an increase in congruity during peak loading of walking and running allows reduction of contact stresses within tolerable limits, while allowing unconstrained mobility of the fixtured components to avoid loosening stresses4. 

Material and Methods :

Between 2000 and 2002 10 LCS knee replacements, were performed by the same surgeon (JV). These knees were fluoroscopically assessed for mobility of the polyethylene bearing. The knee was placed in leg capture to minimize errors secondary to rotations of the tibia. The radio opaque markers present in the mobile bearing were examined fluoroscopically to assess rotation.

 The set up to assess mobility of the LCS knee bearing.

Results :

All knees examined were found to have mobile bearings from 0 degrees to 70 degrees, that could be examined on the fluoroscope. The fluoroscopic image showing radioopaque markers in line on the left and out of line with further flexion on the left, as an evidence for mobility of the rotating platform.

Discussion :

Rotating platform mobile knee prostheses reduce contact stresses by decoupling sagittal plane motion from rotation, thus reducing loosening stresses on the bone prosthesis interface5.Volumetric wear is an important consideration in the longevity of the prosthesis. The volume of wear debris generated in fixed bearing prosthesis increases significantly when subjected to internal- external rotations and anterior– posterior displacements. Inspite of having two surfaces where potential wear is possible rotating platforms exhibited a mean wear of approximately one-third of the fixed bearing prosthesis6. Clinical performace and survivorship of the LCS rotating platform knees into the second decade is very good 4, 5. The biomechanical advantages of decoupling of motion in the sagittal plane from rotations and the resultant decrease in the volumetric wear can only be realized if the rotating platform remains mobile. In this fluoroscopic analysis we have analysed whether rotating platforms remain mobile in vivo.


All the knees examined were found to be mobile at a follow-up ranging from 12 to 30 months. These knees would need to be examined with much longer follow-up to establish if at some point in time these mobile platforms become fixed.

Reference :

  1. Aglietti P, Buzzi R, De Felice R, Giron F. The Insall-Burstein total knee replacement in osteoarthritis: a 10-year minimum follow-up. J Arthroplasty.1999; 14:560 –5.
  2. Stiehl JB, Komistek RD, Dennis DA, Paxson RD, Hoff WA. Fluoroscopic analysis of kinematics after posterior-cruciate-retaining knee arthroplasty. J Bone Joint Surg Br. 1995;77B: 884 –9.
  3. Collier JP, Mayor MB, Mc Namara JL, Surprenant VA, Jensen RE. Analysis of the failure of 122 polyethylene inserts from uncemented tibial knee components. Clin Orthop. 1991; 273: 232-42.
  4. Buechel FF Sr, Buechel FF Jr, Pappas MJ, D’Alessio J. Twenty-year evaluation of the New Jersey rotating platform knee replacement. J Knee Surg.2002; 15: 84-89.
  5. Callaghan JJ, O’Rourke MR, Iossi MF, Liu SS, Goetz DD, Vittetoe DA, Sullivan PM, Johnston RC. Cemented rotating-platform total knee replacement: Aconcise follow-up at a minimum of fifteen years of a previous report. J Bone Joint Surg. Am. 2005; 87A: 1995-7.
  6. McEwen HM, Fisher J, GoldsmithAA, AugerDD, Hardaker C, Stone MH. Wear of fixed bearing and rotating platform mobile bearing knees subjected to high levels of internal and external tibial torsion. J Mater Sci.2001; 12:1049-52.

This is a peer reviewed paper 

Please cite as : Joby John: Do Rotating Platform LCS Knees Continue To Rotate In Vivo?

J.Orthopaedics 2006;3(2)e6





Arthrocon 2011

Refresher Course in Hip Arthroplasty

13th March,  2011

At Malabar Palace,
Calicut, Kerala, India

Download Registration Form

For Details
Dr Anwar Marthya,
Ph:+91 9961303044



Powered by



© Copyright of articles belongs to the respective authors unless otherwise specified.Verbatim copying, redistribution and storage of this article permitted provided no restrictions are imposed on the access and a hyperlink to the original article in Journal of Orthopaedics maintained. All opinion stated are exclusively that of the author(s).
Journal of Orthopaedics upholds the policy of Open Access to Scientific literature.