Abstract
Purpose
Unicompartmental versus total knee arthroplasty has been a debated topic for decades. The purpose of this study was to compare the survivorship and clinical outcomes of a large primary total knee arthroplasty versus unicompartmental knee arthroplasty cohort.
Method
A consecutive series of 6352 TKAs and 296 UKAs with a minimum of one year follow-up were evaluated. Pre-operative scores, latest scores, and change in clinical outcome scores (KSCRS, SF12, WOMAC) were compared and tested for significance using the students t-test.
Results
There were statistically significant differences in baseline demographics between the groups (followup 5.354.04 vs 6.13 4.57, age 67.91 9.52 vs 66.53 8.46, BMI 31.93 6.81 vs 29.57 5.67 in TKAs and UKAs respectively). UKA patients had significantly higher postoperative SF12 Mental Scores and KS scores (p<.05). However they also had significantly higher preoperative scores (p<.05) and it is the change scores that determine the efficacy of the intervention. The change scores for all WOMAC domains (stiffness, pain, function, total) were not different between the groups. The KS change scores were not different between the groups for total scores and favoured TKA over UKA for knee scores (48.9 vs 43.6, p<.0001) and UKA over TKA for function scores (27.03 vs 22.6, p<.05). The SF12 change scores demonstrated no differences between groups for Mental and Physical scores. Cumulative revision rates were 11.7% for UKAs and 7.3% for TKAs.
Conclusion
In this cohort of patients undergoing TKA and UKA, there were significant differences in preoperative and postoperative outcome scores, but much fewer differences in change scores in most domains of WOMAC, SF12 and KSCRS. When comparing outcomes between these interventions it is critical to evaluate change scores and not raw postoperative scores alone.
