The Effect of Unicompartmental Knee Replacement Tibial Component Design on Proximal Tibial Strain and Ongoing Pain: A study of clinical and radiological outcome and finite element analysis

Knee osteoarthritis (OA) is a common degenerative joint disease affecting 12% of the over 60s symptomatically. In approximately 20% of cases this is isolated to the medial compartment of the knee and could be managed with unicompartmental knee replacement (UKR) rather than total knee replacement (TKR). However, the survivorship of UKRs is globally inferior to that of TKRs. Unexplained pain is the second commonest cause for revision of UKR, but this is not the case with TKRs. We hypothesised that elevated proximal tibial strain under medial UKR implants may be a cause of this unexplained pain. The aims of this study are therefore to determine the effect of medial UKR tibial component design on proximal tibial strain and pain.

Three different approaches are being employed to examine the effect of UKR tibial component design on tibial strain and pain:

  1. An observational clinical study of patient reported outcome measures and implant survivorship of cemented UKRs of two different designs:
    1. A mobile bearing UKR implant with a metal backed tibial component
    2. A fixed bearing UKR implant with an all-polyethylene tibial component
  1. To develop a radiographic analysis tool to measure proximal tibial bone density using digital radiological densitometry and apply this to the clinical study patient cohort.
  1. A Finite Element Analysis study, validated by mechanical testing of composite sawbone tibias using acoustic emission, to investigate the effect on strain of  metal backing and implant thickness.

Principal Investigator: 

Dr Pankaj Pankaj

Postgraduate Researchers: 

Chloe Scott

Research Institutes: 

  • Bioengineering