J Knee Surg 2012; 25(05): 407-410
DOI: 10.1055/s-0032-1313756
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Effect of Flexion and Rotation on Measures of Coronal Alignment after TKA

Arun Kannan
1   Department of Orthopaedics, Malabar Orthopaedic Clinic, Windsor, Victoria, Australia
,
Gabrielle Hawdon
1   Department of Orthopaedics, Malabar Orthopaedic Clinic, Windsor, Victoria, Australia
,
Stephen John McMahon
1   Department of Orthopaedics, Malabar Orthopaedic Clinic, Windsor, Victoria, Australia
2   Department of Orthopaedics, Monash University, Victoria, Australia
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Publikationsverlauf

01. September 2011

27. November 2011

Publikationsdatum:
15. Mai 2012 (online)

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Abstract

Attainment of a neutral mechanical axis is one of the primary goals in total knee arthroplasty (TKA). The accuracy of the procedure is evaluated by measuring the hip-knee-ankle angle (HKAA) on long leg radiographs. Rotation of the lower limb and knee flexion could possibly affect the HKAA measured on plain radiographs. In this study, a TKA was performed on a saw-bone model of the lower limb. Long leg radiographs from the femoral head to the ankle were obtained after sequentially varying the alignment of the knee model in 5-degree increments of flexion and rotation, from 0 to 20 degrees. Flexion or external rotation alone, up to 20 degrees changed the HKAA by no more than 1 degree. A combination of flexion and external rotation progressively altered the HKAA. The HKAA was altered by 5 degrees at a combination of 15- or 20-degree flexion and 20-degree external rotation. While flexion or external rotation alone had little effect on the HKAA, a combination of the two altered it substantially.