The natural history of alpha angle in the last seventeen centuries

The Alpha Angle

➢ The alpha angle was originally defined on magnetic resonance imaging (MRI) scans, using a plane, parallel to the axis of the femoral neck. However, much of the literature on the alpha angle has used radiographs or other imaging modalities to quantify the alpha angle.➢ The measurement of the alpha angle can be unreliable, particularly on radiographs and ultrasound.➢ If radiographs are used to measure the alpha angle, the circle of best-fit method should be used on multiple different views to capture various locations of the cam lesion, and "eyeballing" or estimating the alpha angle should be avoided.➢ The cam lesion is a dynamic and 3-dimensional (3D) problem and is unlikely to be adequately defined or captured by a single angle.➢ Modern technology, including readily available 3D imaging modalities, as well as intraoperative and dynamic imaging options, provides novel, and potentially more clinically relevant, ways to quantify the alpha angle.

Femoroacetabular impingement in ancient Nubia 1400-656 BC

INTRODUCTION

There is significant recent interest in femoroacetabular impingement (FAI) in orthopaedics. The etiology of the cam deformity is unknown but has been hypothesized to be due to stresses from sporting activities in our modern society. Few archeological studies exist of femora and FAI. This study reviewed proximal femoral anatomy in a skeletal collection from the ancient Nile valley archeological site at Tombos 1400-656 BC.

METHODS

Digital photographs of the femora were used to obtain angular measurements of the apparent neck shaft, true neck shaft, version, inclination, and α and β angles of Nötzli. All photographs were reviewed by two orthopaedic surgeons for cam and pincer lesions. Sex and age of the specimens was determined when possible. A cam lesion was defined as any femur demonstrating an α angle > 50° or when a cam deformity was seen on visual inspection by both orthopaedic surgeons. Pincer lesions were identified upon visual inspection by both orthopaedic surgeons, when the femoral neck demonstrated impaction lesions, as pelvis radiographs could not be obtained.

RESULTS

There were 126 unique femora; 69 female and 57 male. Age estimates were possible in 100 and was 15-24 years in 14, 25-34 years in 33, 35-49 years in 28, 50-69 years in 17, and ≥ 70 years in 8. There were nine femora (seven individuals) with cam lesions (7%) and five femora (four individuals) with pincer lesions (4%). One demonstrated a combined lesion.

CONCLUSION

FAI existed in ancient Nile valley inhabitants and is thus not only a product of modern day life style athletics. This contrasts with Native Americans living in Ohio 700-1000 AD where no FAI was identified. This difference is likely due to combinations of different types of activity, diet, and genetics. Further research of ancient populations is needed to further answer this question.

LEVEL OF EVIDENCE

IV-cohort study.