Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2017 Dec;88(6):657-663.
doi: 10.1080/17453674.2017.1362733. Epub 2017 Aug 11.

A simple method for accurate rotational positioning of the femoral component in total knee arthroplasty

Eirik Aunan  1 , Daniel Østergaard  2 , Arn Meland  1 , Ketil Dalheim  1 , Leiv Sandvik  3
Affiliations

A simple method for accurate rotational positioning of the femoral component in total knee arthroplasty

Eirik Aunan et al. Acta Orthop. 2017 Dec.

Abstract

Background and purpose - There are many techniques for placing the femoral component in correct rotational alignment in total knee arthroplasty (TKA), but only a few have been tested against the supposed gold standard, rotation determined by postoperative computed tomography (CT). We evaluated the accuracy and variability of a new method, the clinical rotational axis (CRA) method, and assessed the association between the CRA and knee function. Patients and methods - The CRA is a line derived from clinical judgement of information from the surgical transepicondylar axis, the anteroposterior axis, and the posterior condylar line. The CRA was used to guide the rotational positioning of the femoral component in 80 knees (46 female). At 3 years follow-up, the rotation of the femoral component was compared with the CT-derived surgical transepicondylar axis (CTsTEA) by 3 observers. Functional outcome was assessed with the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Oxford Knee Score (OKS) and patient satisfaction (VAS). Results - The mean (95% CI) rotational deviation of the femoral component from the CTsTEA was 0.2° (-0.15°-0.55°). The standard deviation (95% CI) was 1.58° (1.36°-1.85°) and the range was from 3.7° internal rotation to 3.7° external rotation. No statistically significant association was found between femoral component rotation and KOOS, OKS, or VAS. Interpretation - The CRA method was found to be accurate with a low grade of variability.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
A. Before the distal resection of the femur the sTEA was established by marking the most prominent point of the lateral epicondyle and the sulcus on the medial epicondyle with cautery. Thereafter, the APA was marked from the highest point in the intercondylar notch to the deepest point of the trochlea. Then, after distal femoral resection, a line 3° externally rotated compared with the PCL was marked with two pins on the distal femoral cut. B. The parallelism between the sTEA and the PCL +3° was judged with a ruler. C. The orthogonality between the sTEA and the APA and between the PCL +3° and the APA was judged with a transparent angle-measuring device.
Figure 2.
Figure 2.
A. The CT-derived surgical transepicondylar axis (CTsTEA) is the line drawn from the most prominent part of the lateral epicondyle to the sulcus in the medial epicondyle. B. Femoral component rotation is defined by the femoral component rotational axis (FCRA), the common tangent of the 2 pegs on the inside of the femoral component (continuous red line). Then the CTsTEA (stippled red line) from Figure 2A was superimposed, and the femoral component rotational angle (FCR angle) was measured. In this case the angle was 0°.
Figure 3.
Figure 3.
The femoral component rotational angle (FCR angle) relative to the CT-derived surgical transepicondylar axis (CTsTEA) in 80 knees.
See this image and copyright information in PMC

References

    1. Asano T, Akagi M, Nakamura T.. The functional flexion–extension axis of the knee corresponds to the surgical epicondylar axis: In vivo analysis using a biplanar image-matching technique. J Arthroplasty 2005; 20 (8): 1060–7. - PubMed
    1. Aunan E, Naess G, Clarke-Jenssen J, Sandvik L, Kibsgard T J.. Patellar resurfacing in total knee arthroplasty: Functional outcome differs with different outcome scores. A randomized double-blind study of 129 knees with 3 years follow-up. Acta Orthop 2016; 87 (2): 158–64. - PMC - PubMed
    1. Barrack R L, Schrader T, Bertot A J, Wolfe M W, Myers L.. Component rotation and anterior knee pain after total knee arthroplasty. Clin Orthop Relat Res 2001; (392): 46–55. - PubMed
    1. Bell S W, Young P, Drury C, Smith J, Anthony I, Jones B, Blyth M, McLean A.. Component rotational alignment in unexplained painful primary total knee arthroplasty. Knee 2014; 21 (1): 272–7. - PubMed
    1. Berger R A, Rubash H E, Seel M J, Thompson W H, Crossett L S.. Determining the rotational alignment of the femoral component in total knee arthroplasty using the epicondylar axis. Clin Orthop Relat Res 1993; (286): 40–7. - PubMed