Intraoperative Use of Ultrasound for Assessing Cam Deformity and Cam Resection

Figures

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  Fig 1. Left hip of operative patient with cam deformity on traction table in supine position with hip extended. With the hip in neutral rotation (A) and the hip in 30° of internal rotation (B), measurements are made with a goniometer. The ultrasound probe is placed in the transverse oblique plane, parallel to the axis of the femoral neck and perpendicular to the skin. With the hip in extension, 3 views are measured (neutral, 30° of internal rotation, and 30° of external rotation).

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  Fig 2. Left hip of operative patient with cam deformity on traction table in supine position with hip extended. With the hip in 30° of external rotation (A) and the hip flexed to 50° (B), measurements are made with a goniometer. The ultrasound probe is placed in the transverse oblique plane, parallel to the axis of the femoral neck and perpendicular to the skin. With the hip in flexion, 3 views are assessed (neutral, 40° of external rotation, and 60° of external rotation).

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  Fig 3. Ultrasound of a right hip in 50° flexion and 40° external rotation while in the supine position on the traction table. The first step to measuring the alpha angle using the ultrasound is to draw a tangential line (aqua line) next to the spherical head, identifying the distal most point of the joint capsule insertion, approximating the central axis of the femoral neck. This technique is repeated in all 6 dynamic positions of the hip. Green dot denotes the superior and superficial anatomy when utilizing the ultrasound.

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  Fig 4. Ultrasound of a right hip in 50° flexion and 40° external rotation while in the supine position on the traction table. After the tangential line (aqua line) is drawn, to approximate a perfect circle around the femoral head, three points (red X's) are marked along the visible, concentric portion of the head. This technique is repeated in all 6 dynamic positions of the hip. Green dot denotes the superior and superficial anatomy when utilizing the ultrasound.

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  Fig 5. Ultrasound of a right hip in 50° flexion and 40° external rotation while in the supine position on the traction table. After the tangential line (aqua line) is drawn and three points (red X's) are marked along the femoral head, a perfect circle (orange circle) is then created around the femoral head. This technique is repeated in all 6 dynamic positions of the hip. Green dot denotes the superior and superficial anatomy when utilizing the ultrasound.

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  Fig 6. Ultrasound of a right hip in 50° flexion and 40° external rotation while in the supine position on the traction table. Using the center of the perfect circle (orange circle) as a hinge point, a line (aqua line) parallel to the tangential line is drawn down the axis of the femur. Another line (red line) is then drawn from the central portion of the circle to the location where the femoral head loses sphericity, and the alpha angle is calculated, which in this case was 80 degrees. This technique is repeated in all 6 dynamic positions of the hip. Green dot denotes the superior and superficial anatomy when utilizing the ultrasound.

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  Fig 7. Ultrasound (left) and fluoroscopic (right) images of left hip of operative patient on traction table in supine position prior to femoroplasty. The different views of the femoral neck pathology with different rotations (flexion-neutral and flexion–external rotation) can be appreciated, as can the similarity between ultrasound and fluoroscopy. Blue dot denotes superior anatomic position.

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  Fig 8. Ultrasound (left) and fluoroscopic (right) images of left hip of operative patient on traction table in supine position prior to femoroplasty. Different views of the femoral neck pathology with different rotations (flexion-neutral and flexion–external rotation) on both ultrasound and fluoroscopy are shown with alpha angles (blue circles and angle lines) drawn, demonstrating the technique and showing the similarity in measurements. Blue dot denotes superior anatomic position.

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  Fig 9. Ultrasound (left) and fluoroscopic (right) images of left hip of operative patient on traction table in supine position after femoroplasty. The different views of resolution of the femoral neck pathology with different rotations (flexion-neutral and flexion–external rotation) can be appreciated, as can the similarity between ultrasound and fluoroscopy. Blue dot denotes superior anatomic position.

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  Fig 10. Ultrasound (left) and fluoroscopic (right) images of left hip of operative patient on traction table in supine position after femoroplasty with alpha angles (blue circles and angle lines) drawn using described technique. Similarities between ultrasound and fluoroscopy can be noted in the different rotations (flexion-neutral and flexion–external rotation). Blue dot denotes superior anatomic position.