In 1989 Kozinn and Scott published what were at the time the ideal indications for Partial Knee Replacement1. According to their criteria, only 5% of patients were candidates for PKR. This may partly explain why there is low utilisation of PKA today, with it only being used for 8%2,3 of knee replacements worldwide.

An intact, functioning ACL plays a critical role in determining candidacy for PKA.

  • One study showed that 47.6% of all knee replacement patients are candidates for PKA4
  • In a study of consecutive TKAs by Lee et al.5 61% of patients were found to have an intact ACL
  • In a more recent presentation, Berend, et al.6 found 53% of knee replacement candidates had a normal, intact ACL

Utilisation: closing the revision gap

The revision gap between PKA and TKA reported in national joint registries has been reduced with increased utilisation of PKRs:

  • Tregonning, et al in a study reviewing the New Zealand Joint Registry found that surgeons performing at least 12 PKRs per year are found to have a decreased revision rate7
  • Liddle, AD. et al8 found in the National Joint Registry for England and Wales that surgeons utilising PKA for at least 20% of their annual knee replacements experienced a dramatic decrease in their revision rate

What's more, with research showing that up to 61% of patients5 could be candidates for PKA, the optimal usage of performing at least 12 partial knee replacements per year7 can easily be achieved.

* Some studies included Oxford Partial Knees as well as other ‘non-Biomet’ partial knees

  1. Murray, D. et al. The Oxford Medial Unicompartmental Arthroplasty. A Ten-Year Survival Study. Journal of Bone and Joint Surgery. 80:983–989. 1998.
  2. Keys, G. et al. Analysis of First Forty Oxford Medial Unicompartmental Knee Replacements from a Small District Hospital in UK. Knee. 11:375–377. 2004.
  3. Rajasekhar, C. et al. Unicompartmental Knee Arthroplasty. 2- to 12-year Results in a Community Hospital. Journal of Bone and Joint Surgery Br. 86:983–985. 2004.
  4. Price AJ, Svard U.: A second decade lifetable survival analysis of the Oxford unicompartmental knee arthroplasty. Clin Orthop Relat Res. 2011 Jan;469(1): 174-9.
  5. Emerson RH Jr, Higgins LL. Unicompartmental knee arthroplasty with the Oxford prosthesis in patients with medial compartment arthritis. J Bone Joint Surg Am. 2008 Jan;90(1):118-22.
  6. Svard, U. and Price, A. Oxford Medial 1. Unicompartmental Knee Arthroplasty. A Survival Analysis of an Independent Series. Journal of Bone and Joint Surgery Br. 83:191–194. 2001.
  7. Price, A. et al. Long-term Clinical Results of the Medial Oxford Unicompartmental Knee Arthroplasty. Clinical Orthopedics and Related Research. 435:171–180. 2005
  8. Study by researchers at Washington University in St. Louis, Missouri, US. Portions of study funded by Biomet. Determined based on adjusted odds ratio calculation.
  9. Goodfellow, J.W. and O’Connor, J.J. The Mechanics of the Knee and Prosthesis Design. JBJS Br. 60-B(3): 358–69, 1978.
  10. Lombardi, A. et al. Is Recovery Faster for Mobile-bearing Unicompartmental than Total Knee Arthroplasty? Clinical Orthopedics and Related Research. 467:1450-57. 2009.
  11. Amin A, et al. Unicompartmental or Total Knee Replacement? A Direct Comparative Study of Survivorship and Clinical Outcome at Five Years. JBJS Br. 2006; 88-B; Suppl 1, 100. Published Online.
  12. Deshmukh, RV, Scott, RD. Unicompartmental knee arthroplasty: long term results. Clinical Orthopedics and Related Research. 2001; 392:272278.
  13. Brown, NM, et al. Total Knee Arthroplasty Has Higher Postoperative Morbidity Than Uni-compartmental Knee Arthroplasty: A Multicenter Analysis. The Journal of Arthroplasty. (2012)
  14. Robertsson, O, et al. Use of unicompartmental instead of tricompartmental prostheses for unicompartmental arthrosis in the knee is a cost effective alternative. Acta Orthop Scand. (1999); 70(2): 170-175.
  15. Weale AE, Murray DW, Crawford R, et al. Does arthritis progress in the retained compartments after Oxford medial unicompartmental arthroplasty?: a clinical and radiological study with a minimum of 10-year follow up. J Bone Joint Surg[Br] 1999; 80-B: 783-9