Clinical Paper Review: Partial Knee Replacement Could Save The United States More Than $1 billion by 2020


A recent study1 by Dr. Ghomrawi et al. compared the cost-effectiveness of Partial Knee* Replacement (PKR) with Total Knee Replacement (TKR).


The paper draws a few key conclusions from the comparisons of the cost-effectiveness at 5 age points (for 45 year old, 55 year old, 65 year old, 75 year old, and 85 year old patients):

  • Lifetime costs were higher for TKR than for PKR, for all age groups
  • PKRs were more cost effective than TKRs in the age groups 65 and above
  • For the age groups below 65, PKRs would be cost effective if their revision rate was 14.4% (or less) at 10 years and 22.3% (or less) at 20 years follow up. The revision rates used in this article were drawn from the Swedish Knee Arthroplasty Registry.
  • PKR patients, age 65 and older, gained incrementally more QALYs (Quality Adjusted Life Year) than TKR patients

This study expands on previous literature by showing that Partial Knee Replacement can be a cost-effective solution for all age groups. The authors demonstrated that PKR is already cost effective for patients ages 65 and older, and can be cost effective for the younger patients if the PKR revision rate is 14.4% (or less) at 10 years, and 22.3% (or less) at 20 years:

  • Authors from around the world, who are not Oxford® PKR developing surgeons, have reported a 10-year revision rate ranging from 5% to 9% for the Oxford Partial Knee2-7, which is lower than the 14.4%.
  • A further surgeon, who is not an Oxford developer, has reported a 20-year revision rate of 9% for the Oxford Partial Knee8, which is lower than 22.3%.

PKA Candidacy

Ghomrawi et al. also discussed Partial Knee candidacy, and highlighted the underutilization of Partial Knee Replacement: “retrospective studies indicate that 12.0% to 21.0% of patients who undergo total knee arthroplasty were candidates for unicompartmental knee arthroplasty, whereas <8.0% of knee arthroplasties are unicompartmental”.

The authors concluded that PKR could result in societal savings ranging from $167 million to $1088 million as compared to TKR by 2020, based on a PKR candidacy ranging from 10.0% to 21.0%.

  1. Ghomrawi, H. et al. "Effect of age on cost-effectiveness of unicompartmental knee arthroplasty compared with total knee arthroplasty in the U.S.." The Journal of Bone & Joint Surgery 97.5 (2015): 396-402.
  2. Jones, L et al. 10 year survivorship of the medial oxford unicompartmental knee arthroplasty. A 1000 patient non-designer series- the effect of surgical grade and supervision. Osteoarthritis and Cartilage. 2012;20:S290-S291
  3. Faour-Martin, O. et al. Oxford phase 3 unicondylar knee arthroplasty through a minimally invasive approach: long term results. International Orthopaedics, 2013.
  4. Lim, HC et al. Oxford phase 3 unicompartmental knee replacement in Korean patients. JBJS. 2012 Aug; 94-B(8)
  5. Rajasekhar C, Das S, Smith A. Unicompartmental knee arthroplasty. 2- to 12-year results in a community hospital. J Bone Joint Surg Br. 2004; 86:983-985.
  6. Svard UC, Price AJ. Oxford medial unicompartmental knee arthroplasty. A survival analysis of an independent series. Bone Joint Surg [Br] 2001;83-B:191-4.
  7. Yoshida, K et al. Oxford Phase 3 Unicompartmental Knee Arthroplasty in Japan – Clinical Results in Greater Than One Thousand Cases Over Ten Years. The Journal of Arthroplasty 28 Suppl. 2 (2013) 168–171
  8. Price, AJ and Svard, U. A second decade lifetable survival analysis of the Oxford unicompartmental knee arthroplasty. Clin Orthop Relat Res. 2011;469:174-179

  9. *This is a retrospective study of partial knee revision based on revision rates of one, general category (“Partial Knees”) in one registry (Swedish) which included reported Oxford knee results which are not specific to the Oxford partial knee.