Abstract
Introduction
Functional scores are used to clinically assess total hip arthroplasty (THA) and for comparative purposes in the orthopaedic literature. Previous research has highlighted patient age, gender and underlying diagnosis as potential sources of bias but comorbidity has not been considered. The Functional Comorbidity Index (FCI) is a published epidemiological tool which correlates disease with associated physical function deficit. It scores 18 conditions: one point for each, total score 0–18.
Method & Results
We analysed 41 fully cemented primary THAs in patients ≤55 years at time of surgery with a minimum 10 years follow up. Past medical history was collected via thorough case note review. Patients were assessed using the SF-12 questionnaire, Harris Hip and WOMAC indexes.
The study population consisted of 29 patients: 12 women, 17 men. Mean age: 45 years (range 22–53). All patients received cemented polished Corin TaperFit stem with polyethylene Ogee cup. Mean follow up 13.4 years (range 10.2–17.7).
FCI scores ranged 0–3 (12 hips=0; 19 hips=1, 5 hips=2, 5 hips=4). A Pearson's product-moment correlation coefficient was calculated to assess the relationship between co-morbidity and hip function score using all three indexes.
SF-12 score: Mean (M) =88.7; Standard Deviation (SD) =19.3; Range 0–166.
Mean by FCI subgroup: 0=91, 1=96, 2=76.8, 3=68.6 (r=−0.407)
HHS: M=83.8; SD=17.0; Range 45–100.
Mean by FCI subgroup: 0=94.7; 1=88.2, 2=63.5, 3=54.6 (r= −0.813)
WOMAC: M=79.1; SD=20.7; Range 34–100.
Mean by FCI subgroup: 0=94.4, 1=91.72, 2=48.8, 3=37.4 (r=−0.812)
Discussion & Conclusion
Satisfaction was extremely high with 98% of patients “extremely likely” to recommend this treatment to friends or family.
Increasing FCI score correlated with decreasing hip function scores in all three indexes. This study suggests a strong negative correlation between patient comorbidity and hip function scores in THA patients. When comparing functional scores, particularly across patient and implant groups, adjustment for patient comorbidities should be made to ensure balanced evaluation.
