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No difference between patellar retention and resurfacing in TKA at 10 years

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No difference between patellar retention and resurfacing in TKA at 10 years

Vol: 2| Issue: 6| Number:89| ISSN#: 2564-2537
Study Type:Therapy
OE Level Evidence:2
Journal Level of Evidence:N/A

A randomized controlled trial comparing patellar retention versus patellar resurfacing in primary total knee arthroplasty: 5–10 year follow-up

BMC Res Notes. 2012 Jun 7;5:273. doi: 10.1186/1756-0500-5-273

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38 total knee arthroplasty patients with non-inflammatory arthritis were randomized to either patellar resurfacing or to patellar retention to compare functional and revision outcomes over a 10 year time period. Despite the diminishing health, in a ten year follow-up, the results showed that knee pain, stiffness, and function improved in both groups, with no significant differences between them. Both treatment methods had similar revision rates, all occurring within the first 5-years.

Publication Funding Details +
Industry funded
Smith and Nephew INC.

Risk of Bias


Reporting Criteria


Fragility Index


Was the allocation sequence adequately generated?

Was allocation adequately concealed?

Blinding Treatment Providers: Was knowledge of the allocated interventions adequately prevented?

Blinding Outcome Assessors: Was knowledge of the allocated interventions adequately prevented?

Blinding Patients: Was knowledge of the allocated interventions adequately prevented?

Was loss to follow-up (missing outcome data) infrequent?

Are reports of the study free of suggestion of selective outcome reporting?

Were outcomes objective, patient-important and assessed in a manner to limit bias (ie. duplicate assessors, Independent assessors)?

Was the sample size sufficiently large to assure a balance of prognosis and sufficiently large number of outcome events?

Was investigator expertise/experience with both treatment and control techniques likely the same (ie.were criteria for surgeon participation/expertise provided)?

Yes = 1

Uncertain = 0.5

Not Relevant = 0

No = 0

The Reporting Criteria Assessment evaluates the transparency with which authors report the methodological and trial characteristics of the trial within the publication. The assessment is divided into five categories which are presented below.




Outcome Measurements


Inclusion / Exclusion


Therapy Description



Detsky AS, Naylor CD, O'Rourke K, McGeer AJ, L'Abbé KA. J Clin Epidemiol. 1992;45:255-65

The Fragility Index is a tool that aids in the interpretation of significant findings, providing a measure of strength for a result. The Fragility Index represents the number of consecutive events that need to be added to a dichotomous outcome to make the finding no longer significant. A small number represents a weaker finding and a large number represents a stronger finding.

Why was this study needed now?

With the high success rate of total knee arthroplasties (TKA), surgeons still debate the need for patellar resurfacing. Previous studies have shown mixed results and did not investigate the long term effects of this resurfacing procedure. Therefore, the study sought to determine whether there is an existing difference in knee scores and re-operative rates between patellar resurfacing and patellar retention techniques in TKA.

What was the principal research question?

How do knee stiffness, pain, function, and re-operation rates compare between patellar retention and resurfacing, after a 10-year follow-up of TKA?

Study Characteristics -
38 TKA patients with non-inflammatory arthritis and with ages less than 75 years (n=38)
Resurfaced Group: 21 patients who underwent TKA with patellar resurfacing (n=21)
Non-resurfaced Group: 17 patients underwent TKA with patellar retention (n=17)
Western Ontario McMaster Osteoarthritis Index (WOMAC), RAND-36 Questionnaire, and ROM
RCT: Double Blind; Parallel Design;Single-Center
10 years (follow up at 1, 5,and 10 years)

What were the important findings?

  • At both 5 and 10 year follow ups, the groups improved in knee function despite increasing age. No significant differences were noted between the groups (p>0.01).
  • No significant difference in stiffness (WOMAC) was found between groups at 5 year and 10 year follow ups (p>0.01).
  • Both groups significantly improved in pain scores from baseline at 5 and 10 year follow-up, with no significant differences between the groups (p>0.18).
  • All revisions occurred within 5 years, and both groups had similar revision rates (p=0.31). (4 in total)
  • 10% of the patients who retained the patella had to undergo re-operation for persistent anterior knee pain.
  • Both groups deteriorated in overall health status within 10 years according to RAND-36 General Health Scores.

What should I remember most?

The results of a ten year follow-up demonstrated that no significant differences existed between patients who received patellar resurfacing versus patients who did not undergo patellar resurfacing in terms of knee pain, stiffness, and function. However, 10% of the patients who retained the patella had to undergo re-operation for persistent anterior knee pain. Unfotunately, this study was under powered to detect differences in re-operation rate.

How will this affect the care of my patients?

Although there were no major significant differences found between patellar resurfacing group and the patellar retention group, there was a slight difference in re-operation rates for the retaining group. Further studies with objective outcomes, such as radiographic and surgical analyses, as well as larger population sizes are needed to draw clear conclusions.

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