What is the neck shaft angle range for Univers II and Apex Cups?

• A. 120-140
• B. 135-155
• C. 140-170
• D. 125-145

Answer: (B)

The neck-shaft angle is the angle between the axis of the femoral neck and the axis of the femoral shaft, and it influences how the prosthetic neck sits relative to the thigh bone, affecting the hip’s center of rotation, leg length, and soft-tissue tension. For the Univers II and Apex Cups, the components are designed to work with a neck angle range of 135 to 155 degrees. This span provides enough variability to match typical patient anatomy while preserving appropriate biomechanics, helping to maintain a good abductor lever arm, stable joint position, and smooth range of motion without undue impingement against the cup rim. The other ranges either constrain or exceed what these designs are intended to accommodate, which could compromise alignment, stability, or impingement risk.