The Transepicondylar Axis Approximates the Optimal Flexion Axis of the Knee

Churchill, David L.; Incavo, Stephen J.; Johnson, Christopher C.; Beynnon, Bruce D.

doi:10.1097/00003086-199811000-00016

Cited by 461 publications

(356 citation statements)

References 15 publications

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“…Churchill et al [6] found, in their study of 15 cadaveric specimens, that the TEA approximated the optimal flexion axis of the knee as defined by a compound hinge mathematical model. However, we found these two axes to be nonparallel, with a mean difference of 2.9°, which might be accounted for by their use of the TEA rather than the surgical TEA.…”

Section: Discussionmentioning

confidence: 99%

“…From 10°to 150°tibiofemoral flexion, the centers of rotation were found to lie on a line connecting the area of attachment of the medial collateral ligament and the lateral collateral ligament [11]. However, this model included out-of-plane movement of both centers, which could not be explained through a single, fixed axis of rotation [6]. Hollister et al [13] used a mechanical device, the ''axis finder'', to locate a flexion-extension axis and a longitudinal rotation axis, with all positions of knee flexion occurring through movement about these two axes in a compound hinge model.…”

Section: Introductionmentioning

confidence: 95%

“…Churchill et al suggested matching femoral rotation to the TEA most closely matched the mean flexion axis of the knee in 15 cadaveric specimens [6]. Kurosawa et al [18] observed the spherical nature of the posterior condyles and identified the location of the centers of these spheres, which coincided with the center of the condyles on lateral radiographs.…”

Section: Introductionmentioning

confidence: 97%

“…The helical axis model [23][24][25]27] has a moving axis of rotation about which all tibiofemoral motion takes place. This can be viewed as a combination of the two axes suggested by the compound hinge model [6]. This helical model was used in our study to locate the functional flexion axis (FFA).…”

Section: Introductionmentioning

confidence: 99%

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Is Femoral Component Rotation in a TKA Reliably Guided by the Functional Flexion Axis?

Oussedik

Scholes

Ferguson

et al. 2012

Clinical Orthopaedics &Amp; Related Research

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Background The position of the femoral component in a TKA in the axial plane influences patellar tracking and flexion gap symmetry. Errors in femoral component rotation have been implicated in the need for early revision surgery. Methods of guiding femoral component rotation at the time of implantation typically are derived from the mean position of the flexion-extension axis across experimental subjects. The functional flexion axis (FFA) of the knee is kinematically derived and therefore a patient-specific reference axis that can be determined intraoperatively by a computer navigation system as an alternative method of guiding femoral component rotation. However, it is unclear whether the FFA is reliable and how it compares with traditional methods. Question/purposes We asked if the FFA could be measured reproducibly at different stages of the operative procedure; (2) where it lies in relation to a CT-derived gold standard; and (3) how it compares with more traditional methods of judging femoral component rotation. Methods Thirty-seven patients undergoing elective TKAs were recruited to the study. Preoperative CT scans were obtained and the transepicondylar axis (TEA) was identified. The TKA then was performed using computer navigation. The FFA was derived before incision and again after the surgical approach and osseous registration. The navigation system was used to register the surgical TEA. The FFA and surgical TEA then were compared with the CT-derived TEA. Results The mean preincision FFA was similar to the intraoperative FFA and therefore deemed reproducible. We observed no differences in variability between surgical TEA and preincision FFA. The FFA was different from the CT-TEA and judged similar in accuracy to the surgical TEA. Conclusion The reliability and accuracy of the FFA were similar to those of other intraoperative methods. Further evaluation is required to ascertain whether the FFA improves on currently available methods for determining the ideal rotation of the femoral component during TKA.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Is Femoral Component Rotation in a TKA Reliably Guided by the Functional Flexion Axis?

Oussedik

Scholes

Ferguson

et al. 2012

Clinical Orthopaedics &Amp; Related Research

View full text Add to dashboard Cite

show abstract

“…This single axis around which the tibia rotates in space is not captured in any of the traditional coronal, sagittal, or transverse planes and attempts to project it onto these planes gives rise to an artifact. Therefore the use of a surrogate axis passing through identifiable landmarks has been proposed as a solution [1,2,[4][5][6][7]30]. Churchill et al [6] suggested a line passing through the most medial and lateral portions of the epicondyles, the transepicondylar axis (TEA), best approximates the actual flexion-extension axis (FEA) of the knee.…”

Section: Introductionmentioning

confidence: 99%

Cylindrical Axis, Not Epicondyles, Approximates Perpendicular to Knee Axes

Hancock

Winston

Bach

et al. 2013

Clinical Orthopaedics &Amp; Related Research

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Background The transepicondylar axis (TEA) is often used as a surrogate for the flexion-extension axis, ie, the axis around which the tibia moves in space, because of a belief that both axes lie perpendicular to the mechanical axis. However, studies suggest the cylindrical axis (CA), defined as a line equidistant from contact points on the medial and lateral condylar surfaces from 10 o to 120 o flexion, more closely approximates the axis around which the tibia moves in space.Questions/purposes We examined the TEA and CA angles relative to mechanical axes to determine whether one more consistently and closely approximates the surgical goal of orthogonality to the mechanical axis. Methods Three-dimensional (3-D) models were reconstructed from CT scans of five cadaver limbs. Three observers repeated three measurement sets to locate the TEA, CA, and femoral mechanical and tibial mechanical axes. Angles of the TEA and CA relative to the mechanical axes were calculated in two-dimensions (2-D) and as 3-D projections and compared for differences in magnitude and variance. Results Angles between CA and the mechanical axes were closer to 90°than the TEA in 2-D (92°versus 94°for the femur, 93°versus 94°for the tibia) and 3-D (88°versus 87°for the femur, 88°versus 86°for the tibia). Variance of the TEA was higher than the CA in 2-D. Conclusions The CA forms angles more orthogonal to the mechanical axes of the thigh and leg than the TEA. Clinical Relevance Although we found a consistently greater deviation of the TEA from the mechanical axis than the CA with small differences, future studies will need to determine whether these differences are biomechanically or clinically important.

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Quantifying lateral femoral condyle ellipticalness in chimpanzees, gorillas, and humans

Sylvester

Pfisterer

2012

American J Phys Anthropol

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Articular surfaces of limb bones provide information for understanding animal locomotion because their size and shape are a reflection of habitual postures and movements. Here we present a novel method for quantifying the ellipticalness (i.e., departure from perfectly circular) of the lateral femoral condyle (LFC), applying this technique to hominid femora. Three-dimensional surface models were created for 49 Homo sapiens, 34 Pan troglodytes and 25 Gorilla gorilla femora. Software was developed that fit separate cylinders to each of the femoral condyles. These cylinders were constrained to have a single axis, but could have different radii. The cylinder fit to the LFC was allowed to assume an elliptical cross-section, while the cylinder fit to the medial condyle was constrained to remain circular. The shape of the elliptical cylinder (ratio of the major and minor axes of the ellipse) was recorded, and the orientation of the elliptical cylinder quantified as angles between the major axis of the ellipse and the anatomical and mechanical axes of the femur. Species were compared using analysis of variance and post hoc multiple comparisons tests. Confirming qualitative descriptions, human LFCs are more elliptical than those of chimpanzees and gorillas. Human femora exhibit a narrow range for the angle between the major axis of the elliptical cylinder and femoral axes. Conversely, the chimpanzee sample is bimodal for these angles, exhibiting two ellipse orientations, while Gorilla shows no preferred angle. Our results suggest that like modern human femora, chimpanzee femoral condyles have preferentially used regions.

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The Transepicondylar Axis Approximates the Optimal Flexion Axis of the Knee

Cited by 461 publications

References 15 publications

Is Femoral Component Rotation in a TKA Reliably Guided by the Functional Flexion Axis?

Is Femoral Component Rotation in a TKA Reliably Guided by the Functional Flexion Axis?

Cylindrical Axis, Not Epicondyles, Approximates Perpendicular to Knee Axes

Quantifying lateral femoral condyle ellipticalness in chimpanzees, gorillas, and humans

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