Is presence of patella baja a cause for pain and functional problems after total knee replacement ? A 10 year follow-up study

Abstract

Evidence in the literature reports that Patella baja is linked to pain and low function after Total Knee Replacement (TKR).

This study evaluates the significance of post- operative Patella baja on patient reported outcome and function after a minimum follow up of 10 years following TKR.

125 total knee replacements (in 125 patients) operated in our unit were identified retrospectively from the theatre database and were reviewed clinically and radiologically after 10 years. The Caton – Deschamps (CD) Index was used to radiological categorisation of patellar height. Pain and functional scores were recorded using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Society Score (KSS) and Oxford Knee Scoring (OKS) systems.

Of the 125 patients reviewed, 39 (31.2%) patients had radiological evidence of Patella baja and the remaining 86 (68.8 %) patients had normal patellar height. There was no significant difference in the pain and functional scores (using WOMAC, KSS and OKS scores) between the two patient groups.

We conclude that Patella baja had no long term significance with regards to patient reported pain and functional outcomes in our study. This study provides substantial opposition to the current opinion that Patella baja is commonly responsible for pain following TKR. The clinical assessment for identifying the cause of persistent knee pain and functional disability should be focused elsewhere. Patellar height abnormality should not determine the need for increasing the long term post-operative follow-up after total knee replacement.