Two‐Tiered Resection of Cam Lesions in Hip Femoroacetabular Impingement: Optimizing Femoral Head Sphericity

Fig 1. Artistic rendering of the 2-tiered resection of a right hip as seen from the Dunn lateral view. (A) Pre-resection view of the cam lesion. (B) Creation of the tier 1 resection, in which the depth of resection is set to re-create the appropriate head-neck offset. This is performed 1.5 burr lengths distal to the articular cartilage margin. (C) Completion of the tier 2 resection, which resects the cam lesion distal to tier 1 to the same depth and re-creates the sphericity of the femoral head.

Fig 2. Radiographic imaging of the preoperative template drawn from the Dunn lateral view of a right hip, which is used in the surgical suite to guide resection. The outline shows the plan for resection to begin at the physeal scar, proximally countering to re-create the sphericity of the femoral head as well as to match the alpha angle to the beta angle, which is analogous to the alpha angle performed on the posterior aspect.

Fig 3. Clinical photograph of the surface landmarks and preoperative markings of the portals to be used during cam resection. This photograph is taken laterally of the left hip with the patient supine on a post-free hip distraction table. The bony landmarks of the anterior superior iliac spine (ASIS) and the greater trochanter (GT) are used as references to create the anterolateral portal (AL), distal anterolateral portal (DALA), and midanterior portal (MAP).

Fig 4. (A) Arthroscopic view of the articular cartilage margin as seen from the distal anterolateral portal with the left hip in 30° of flexion and neutral rotation. The identification of the articular cartilage margin is used as a reference for the tier 1 resection. The tier 1 resection is begun roughly 1.5 burr lengths distal to this margin. (B) Fluoroscopic imaging taken with a 45° Dunn lateral view. This image is used prior to beginning cam resection to confirm the location of the proximal femoral physeal scar. This will be used as the proximal extent of the osteoplasty. In this image, the arthroscopic burr is positioned on the physeal scar.

Fig 5. (A) Arthroscopic view after the completion of the tier 1 resection as seen through the distal anterolateral portal with the left hip in 30° of flexion and neutral rotation. This tier creates the depth of resection required to achieve the native head-neck offset. The resection is begun 1.5 burr lengths distal to the articular cartilage margin. (B) Fluoroscopic imaging obtained via a 45° Dunn lateral view after completion of the tier 1 resection to ensure the appropriate depth has been set. The tier 1 resection can be deepened based on imaging to re-create the native offset at the head-neck junction.

Fig 6. (A) Direct visualization of the completed osteoplasty through the distal anterolateral portal with the left hip in 30° of flexion and neutral rotation. Fluoroscopic imaging, along with evaluation of dynamic hip range of motion under direct visualization, is also used to confirm adequate resection of the cam lesion. (B) Fluoroscopic imaging obtained from a 45° Dunn lateral view of the completed osteoplasty. Direct visualization of the cam during dynamic hip range of motion is used to ensure adequate cam resection.