Embedded Image Clarify the concept of primary cam morphology and its natural history, using a clear definition: primary cam morphology is a cartilage or bony prominence (bump) of varying size at any location around the femoral head-neck junction of the hip, which changes the shape of the femoral head from spherical to aspherical. Development likely begins in early adolescence, occurring most often in asymptomatic male athletes in both hips.
Embedded Image Validate athletes’ and patients’ experiences through consistent, positive terminology; use ‘morphology’, ‘prominence’ or ‘bump’ when referring to the morphology; avoid ‘lesion’, ‘deformity’ and ‘abnormality’—words that could amplify the need for unnecessary interventions; consider the possible negative connotation of ‘syndrome’.
Embedded Image Apply a consistent taxonomy for cam morphology that distinguishes between primary and secondary cam morphology: primary cam morphology develops during skeletal maturation in young adolescents (with no current or previous hip disease), as a normal physiological response to high-load sporting activity, and is largely benign; secondary cam morphology develops secondary to primary (hip) disease—an important distinction that empowers athletes and patients to embrace normality and their ‘happy hips’.
Embedded Image Describe the alpha-angle on radiographs or 3D imaging, depending on the clinical and/or research context, to measure (operationalise) the morphology: the preferred outcome measure for research on primary cam morphology aetiology is a cartilage or bone alpha angle as a continuous variable on radial MRI along the axis of the femoral neck, using 30° intervals from 12 o'clock to 11 o'clock positions, reported per hip, per person or both. In addition to reporting the morphology as a continuous alpha angle (in degrees), a dichotomous alpha angle (using a threshold of ≥60°) can be useful in clinical practice or research.