Does patella resurfacing really matter? Pain and function in 972 patients after primary total knee arthroplasty

Abstract

Background and purpose Resurfacing of the patella during primary total knee arthroplasty (TKA) is often recommended based on higher revision rates in non-resurfaced knees. As many of these revisions are insertions of a patella component due to pain, and since only patients with a non-resurfaced patella have the option of secondary resurfacing, we do not really know whether these patients have more pain and poorer function. The main purpose of the present paper was therefore to assess pain and function at least 2 years after surgery for unrevised primary non-resurfaced and resurfaced TKA, and secondary among prosthesis brands.

Methods Information needed to calculate subscales from the knee injury and osteoarthritis outcome score (KOOS) was collected in a questionnaire given to 972 osteoarthritis patients with intact primary TKAs that had been reported to the Norwegian Arthroplasty Register. Pain and satisfaction on visual analog scales and improvement in EQ-5D index score ΔEQ-5D) were also used as outcomes. Outcomes were measured on a scale from 0 to 100 units (worst to best). To estimate differences in mean scores, we used multiple linear regression with adjustment for possible confounders.

Results We did not observe any differences between resurfacing and non-resurfacing in any outcome, with estimated differences of ≤ 1.4 units and p-values of > 0.4. There was, however, a tendency of better results for the NexGen implant as compared to the reference brand AGC for symptoms (difference = 4.9, p = 0.05), pain (VAS) (difference = 8.3, p = 0.004), and satisfaction (VAS) (difference = 7.9, p = 0.02). However, none of these differences reached the stated level of minimal perceptible clinical difference.

Interpretation Resurfacing of the patella has no clinical effect on pain and function after TKA. Differences between the brands investigated were small and they were assumed to be of minor importance.

Acknowledgments

SHL: study design, data collection, and statistical analysis. BE: study design and statistical supervision. LIH: medical supervision. SEV: study design and statistical supervision. OF: study design and medical supervision. All authors were involved in the writing of the manuscript.

We thank Mrs Eva Dybvik, Ms Kaia Furnes, Ms Ronja Furnes, and Mr Ørjan SØrnes for registration of questionnaires. We also thank Mrs Inger Skar, secretary of the Norwegian Arthroplasty Register, for her accurate registration of each knee replacement reported. We also extend our thanks to the Norwegian orthopedic surgeons in 83 hospitals for reporting their cases to the register, and to all the patients who completed the forms for this study. The study was supported by the Norwegian Rheumatism Association and has been financed with the aid of EXTRA funds from the Norwegian Foundation for Health and Rehabilitation.

No competing interests declared.

Supplementary data. Table 1 and Figure 4 can be found on the www.actaorthop.org website, identification number 3061/09.

Notes