Premium
MULTIPARAMETER QUANTITATIVE COMPUTER‐ASSISTED TOMOGRAPHY ASSESSMENT OF UNICOMPARTMENTAL KNEE ARTHROPLASTIES
Author(s) -
Campbell DAVID G.,
Johnson LUKE J.,
West SIMON C.
Publication year - 2006
Publication title -
anz journal of surgery
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.426
H-Index - 70
eISSN - 1445-2197
pISSN - 1445-1433
DOI - 10.1111/j.1445-2197.2006.03867.x
Subject(s) - medicine , tomography , unicompartmental knee arthroplasty , computed tomography , radiology , osteoarthritis , pathology , alternative medicine
Background: Unicompartmental knee arthroplasty is a popular alternative to total knee replacement in selected patients. Component alignment has not yet been described by computer‐assisted tomography (CAT) imaging techniques; these have been developed for total knee arthroplasty analysis. The aims of this study were to report two new technologies; a new unicompartmental knee arthroplasty system was radiographically assessed with a new CAT scan protocol. Methods: In a consecutive cohort study, 60 knees were analysed by the ‘UniCAT Protocol’. Patients were implanted with a unicompartmental knee arthroplasty system that uses a unique ligament tensor for femoral component alignment. The uniCAT protocol requires a long anteroposterior and lateral scout scan to measure limb alignment and component orientation. A spiral computer‐assisted tomography at the knee is used to measure component rotation. The total scan time was 20 s with a calculated unshielded radiation dose of 1 mSv or less. Results: The mechanical axis had a mean of 2.7° varus. Femoral components were implanted with a mean of 0.37° valgus and 1.3° flexion. Tibial components were implanted with a mean 3.47° varus and 5.1° posterior slope. Femoral components were externally rotated a mean of 3.36°, tibial components were externally rotated 6.59° from the posterior tibia and 5.68° from the transepicondylar axis. Conclusion: The UniCAT protocol uses less radiation than whole‐limb spiral scans and is a method that can be used with all modern computer‐assisted tomography machines. The coronal and sagital alignment results compare favourably with previous published reports without computer‐assisted tomography. Component rotation has not previously been reported and its implications are yet to be defined.