Summary

There was no statistical significant difference in KOOS between patients with patella infera and patients with normal patellar high after total knee arthroplasty.

Abstract

Background

Patella infera is a condition of abnormally low-lying patella which might occur after the total knee arthroplasty. Reason for patella infera after operation might be arthrofibrosis which may lead to chronic pain and restricted range of motion. The aim of our study was to find the corellation of postoperative results between patients with patella infera and patient with normal patellar high.

Methods

We reviewed the x-ray images of 298 patients who were implanted the total knee endoprothesis in 2013. Insall-Salvati and modified Blackbourne-Peel ratios were measured from pre-operative and post-operative images. According to the results, the patients were assigned to either study group consisting of 38 patients (at least 1 ratio must have been positive) or control group consisting of 35 randomly selected patients whose knee ratios were absolutely negative. Knee injury and Osteoarthritis Outcome Score (KOOS) was measured preoperatively and at follow up. We compared KOOS preoperatively and postoperatively for both study groups.

Results

Pain subscale average score rised from 30 to 70 in control group and from 21 to 70 in study group. Symptoms scale average score rised from 49 to 72 in control groups while in study group it rised from 41 to 65. Function in daily living scale average score rised from 34 to 70 in control group and from 31 to 70 in study group. Function is sports and recreation average score rised from 25 to 48 in control group and from 11 to 49 in study group. The Quality of life average score rised from 20 to 50 in control groups while it rised from 17 to 49 points in study group. We found no statistical diference between both gropus preoperatively or postoperatively for any KOOS subscale.

Conclusions

There was no statistical significant difference in KOOS between patients with patella infera and patients with normal patellar high after total knee arthroplasty. Further studies are needed to determine the range of motion in these patients as well as another x-ray imaging.