Three-Dimensional Morphology of the Distal Part of the Femur Viewed in Virtual Reality by Donald G. Eckhoff, Thomas F. Dwyer, Joel M. Bach, Victor M. Spitzer, and Karl D. Reinig J Bone Joint Surg Am Volume 83(2 suppl 1):S43-50 October 1, 2001 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The stereotactic micrometer, originally designed to localize intracranial lesions in neurosurgery, was modified to hold cadaveric femora for topographical mapping of the condyles and the trochlear groove. The stereotactic micrometer, originally designed to localize intracranial lesions in neurosurgery, was modified to hold cadaveric femora for topographical mapping of the condyles and the trochlear groove. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The stylus of the micrometer moves horizontally and vertically in millimeter increments to allow measurements of depth, in millimeters, of the articular surface of the condyles and the trochlea in the horizontal plane. The stylus of the micrometer moves horizontally and vertically in millimeter increments to allow measurements of depth, in millimeters, of the articular surface of the condyles and the trochlea in the horizontal plane. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

A side view of the knee simulator, with the femoral unit on the left and the tibial unit on the right. A side view of the knee simulator, with the femoral unit on the left and the tibial unit on the right. The knee is oriented with the patella pointed down and the tibia parallel to the horizontal. The femoral carriage swings through a vertical plane to allow flexion/extension. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

An end view of the knee simulator, with the viewer looking at the tibial unit from distal to proximal. An end view of the knee simulator, with the viewer looking at the tibial unit from distal to proximal. Movement of the tibial carriage to the left or right allows abduction/adduction. The three large wheels in this image have been replaced by air-bearings to further reduce friction. A downward motion represents anterior tibial displacement, whereas an upward motion would be posterior displacement. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

Schematic representation of the knee simulator. Schematic representation of the knee simulator. The upper image is a top view oriented from posterior to anterior. The lower image is a side view, with the tibial unit on the left and the femoral unit on the right. A/P = anterior/posterior, I/E = internal/external rotation, M/L = medial/lateral, F/E = flexion/extension, C/D = compression/distraction, and A/A = abduction/adduction. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

A side view of the knee simulator focusing on the details of the flexion/extension actuation. A side view of the knee simulator focusing on the details of the flexion/extension actuation. The hamstring muscle actuator can be seen in the upper-right portion of the image, and the axial rotation actuator can be seen in the foreground of the lower-left portion of the image. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

A table showing the design load capabilities of the knee simulator. A table showing the design load capabilities of the knee simulator. The design external loads are capable of disrupting the structures of the healthy knee joint. The muscle loads approach physiologic levels. F/E = flexion/extension, I/E = internal/external rotation, A/A = abduction/adduction, M/L = medial/lateral, A/P = anterior/posterior, C/D = compression/distraction, QUA = quadriceps, HAM = hamstrings, and GAS = gastrocnemius. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The femoral unit of the knee simulator with the femoral alignment fixture installed. The femoral unit of the knee simulator with the femoral alignment fixture installed. This alignment fixture allows six-degrees-of-freedom adjustment of the femur with respect to the femoral unit. There is a similar alignment fixture for the tibia (not shown). Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

Forty knees (forty patients) with osteoarthritis of the medial compartment presenting for total knee arthroplasty were scanned with computed tomography, and the measurements were compared with those for forty normal knees in age-matched controls. Forty knees (forty patients) with osteoarthritis of the medial compartment presenting for total knee arthroplasty were scanned with computed tomography, and the measurements were compared with those for forty normal knees in age-matched controls. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

Thirty-four knees (thirty-four patients) with anterior pain were scanned with computed tomography, and the measurements were compared with those for thirty-four normal knees in age-matched controls. Thirty-four knees (thirty-four patients) with anterior pain were scanned with computed tomography, and the measurements were compared with those for thirty-four normal knees in age-matched controls. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

Computed tomographic scans were performed with the knee in extension by transversely “cutting” the femur proximal to the intercondylar notch and the tibia proximal to the tubercle. Computed tomographic scans were performed with the knee in extension by transversely “cutting” the femur proximal to the intercondylar notch and the tibia proximal to the tubercle. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The distal femoral and proximal tibial computed tomography cuts were superimposed to measure relative translation (see Fig. 19) and rotation (see Fig. 20). The distal femoral and proximal tibial computed tomography cuts were superimposed to measure relative translation (see Fig. 19) and rotation (see Fig. 20). The proximal and distal femoral cuts were superimposed to measure femoral version (see Fig. 21). Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The transverse image shown in Fig The transverse image shown in Fig. 13-A is one of the 1877 1-mm-spaced transverse images of the Visible Human Male. The transverse image shown in Fig. 13-A is one of the 1877 1-mm-spaced transverse images of the Visible Human Male. The collection of 1877 images forms a volume of photographic data. This volume can be “resliced” at any angle to form other cross-sectional images, such as the coronal one shown in Fig. 13-B and the sagittal one shown in Fig. 13-C. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The transverse image shown in Fig. 14-A is one of the 5189 0 The transverse image shown in Fig. 14-A is one of the 5189 0.33-mm-spaced transverse images of the Visible Human Female. The transverse image shown in Fig. 14-A is one of the 5189 0.33-mm-spaced transverse images of the Visible Human Female. The resolution of this transverse image is comparable with that of the image of the male counterpart shown in Fig. 13-A. Like the volume of the male, this volume can also be “resliced” at any angle to form other cross-sectional images, such as the coronal one shown in Fig. 14-B and the sagittal one shown in Fig. 14-C. The resolution of these “resliced” images is more than three times higher than the resolution of the images of the male counterpart because of the thinner slice thickness for the female. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The transverse image shown in Fig. 15-A is one of the 2500 0 The transverse image shown in Fig. 15-A is one of the 2500 0.10-mm-spaced transverse images of a right-knee specimen. The transverse image shown in Fig. 15-A is one of the 2500 0.10-mm-spaced transverse images of a right-knee specimen. Like the whole-body volumes, this knee volume can also be “resliced” at any angle to form other cross-sectional images, such as the coronal one shown in Fig. 15-B and the sagittal one shown in Fig. 15-C. The resolution of these “resliced” images is more than ninety times higher than the resolution of the images of the male counterpart and nearly thirty times higher than that of the images of the female counterpart because of thinner slice thickness and higher “in-plane” resolution. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The femur of the Visible Human Male has been extracted from the volumetric computed tomography data represented in Figs. 13-A, 13-B, and 13-C. The femur of the Visible Human Male has been extracted from the volumetric computed tomography data represented in Figs. 13-A, 13-B, and 13-C. A cylinder was then fit to the osseous surface of the distal part of the femur. Note that the radius of the cylinder fit to the medial femoral condyle is slightly larger than the radius of the cylinder fit to the lateral femoral condyle, but the center of each cylinder lies on a single axis. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The sulcus (lowest point) is a nearly linear depression in the trochlear groove that lies lateral to the midplane, defined as the plane perpendicular to the posterior condylar axis. The sulcus (lowest point) is a nearly linear depression in the trochlear groove that lies lateral to the midplane, defined as the plane perpendicular to the posterior condylar axis. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The sulcus is oriented between the traditional mechanical axis (the line joining the center of the femoral head and the center of knee) and the anatomic axis (the center of the femoral shaft). The sulcus is oriented between the traditional mechanical axis (the line joining the center of the femoral head and the center of knee) and the anatomic axis (the center of the femoral shaft). Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The cross-sectional centers of the distal part of the femur and the proximal part of the tibia are not superimposed but are translated 4±6 mm anteroposteriorly and 5±4 mm mediolaterally in both normal knees and those with osteoarthritis or ant... The cross-sectional centers of the distal part of the femur and the proximal part of the tibia are not superimposed but are translated 4±6 mm anteroposteriorly and 5±4 mm mediolaterally in both normal knees and those with osteoarthritis or anterior pain. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

In an extended knee with pathological findings, there is rotation of the tibia in relation to the femur fixed in soft tissue—a “rotation” contracture. In an extended knee with pathological findings, there is rotation of the tibia in relation to the femur fixed in soft tissue—a “rotation” contracture. The tibia is externally rotated in relation to the femur in both the osteoarthritic knees (4°±1°) and the knees with anterior pain (7°±1°). There is no rotation of the tibia in relation to the femur, or rotation contracture, in the normal knees. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The distal part of the femur is malrotated relative to the proximal part of the femur in the osteoarthritic knees and the knees with anterior pain when compared with the normal knees. The distal part of the femur is malrotated relative to the proximal part of the femur in the osteoarthritic knees and the knees with anterior pain when compared with the normal knees. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

The distal part of the femur of a knee with anterior pain, viewed here with computed tomography, is rotated when the proximal part of the femur is normally oriented in relation to the acetabulum. The distal part of the femur of a knee with anterior pain, viewed here with computed tomography, is rotated when the proximal part of the femur is normally oriented in relation to the acetabulum. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

Experimental data for eight cadaveric knees. Experimental data for eight cadaveric knees. These data show the coupled axial rotation of the tibia during flexion/extension of the femur following functional alignment. Note the extremely small variability attributable to the alignment procedures. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

One view of the Interactive Anatomic Animation of the distal part of the femur illustrates the three-dimensional relationship between the epicondylar axis (green line) and the “cylindrical axis” (red line), defined by the center of the cylinders that most c... One view of the Interactive Anatomic Animation of the distal part of the femur illustrates the three-dimensional relationship between the epicondylar axis (green line) and the “cylindrical axis” (red line), defined by the center of the cylinders that most closely reproduce the geometry of the condyles. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.

A femoral component designed with asymmetric features addresses the natural asymmetry of the human knee. A femoral component designed with asymmetric features addresses the natural asymmetry of the human knee. Donald G. Eckhoff et al. J Bone Joint Surg Am 2001;83:S43-50 ©2001 by The Journal of Bone and Joint Surgery, Inc.