Abstract
Surgeons theorize smaller increments in sizing might better address different sized femurs and size differences between genders. This study examines utilisation of intermediate sized components to determine if availability affects outcomes of women and men undergoing total knee arthroplasty (TKA).
We reviewed 1903 consecutive, primary TKA in 1519 patients (64% women) performed with a single implant system. Originally, six femoral sizes were available; four intermediate sizes were added later. The system allows interchange ability of all femoral and tibial sizes and has seven constraint options. Four hundred and five TKA were done prior to intermediate size availability. In women before, 49% were 65mm, 47% 60mm, and 3% 70mm. After, 32% were 62.5mm, 21% 65mm and 8% 67.5mm. In men, 70mm was the most common representing 49% before and 41% after. The 65mm in men dropped from 29% before to 16% after and the 75mm dropped from 21% to 14%. After, 23% were 67.5mm. Minimum follow-up was two years.
When comparing women before versus after, women after had significantly better postoperative Knee Society (KS) pain (p=0.0000), clinical (p=0.003) and function scores (p=0.0000), and improvement in clinical (p=0.0000) and function scores (p=0.0001) while improvement in pain score was similar. Men done after had better postoperative KS pain (p=0.02) and function scores (p=0.002), and improvement in KS clinical (p=0.001) and function (p=0.0002) scores.
Both men and women undergoing TKA after availability of half sizes had better postoperative KS pain, clinical and functional scores, and improvement from preoperative levels compared with men and women before. We conclude a single TKA system with a wide variety of sizing and constraint options can provide consistently excellent results for both men and women undergoing TKA.
Correspondence should be addressed to Diane Przepiorski at ISTA, PO Box 6564, Auburn, CA 95604, USA. Phone: +1 916-454-9884; Fax: +1 916-454-9882; E-mail: ista@pacbell.net
