Does the femoral head/neck contour in the skeletally mature change over time?

Luca Gala,Kawan S Rakhra,Vickas Khanna,Paul E Beaulé

doi:10.1093/jhps/hnw022

Abstract

The purpose of this study was to determine whether anterior/anterolateral femoral head/neck contour of the hip is static or dynamic over time within the context of the cam deformity. From a previously published cohort of 200 asymptomatic patients who had a magnetic resonance imaging (MRI) of their hips, 23 patients were randomly selected: 10 with a cam lesion and 13 with no evidence of a cam lesion in either hip. There were 7 females and 16 males with a mean age of 37.5 years (range 30–56 years). A repeat MRI or computed tomography scan was performed. Femoral head/neck contour was assessed with alpha angle measurements at the 3 and 1:30 positions. At mean time of 5.3 years (range 2.5–7.2 years) between the two time points, the mean alpha angle for the entire cohort was not significantly different with alpha angle of 43.4°/53.7° (3:00/1:30 positions) at first visit and 46.1°/54.2° (3:00/1:30 positions) at second visit, respectively. Subdividing the cohort into cam negative and cam positive groups, there are no clinically relevant differences (i.e. <5°) between the two alpha angle measurements. Inter-observer reliability had an intra-class coefficient at 0.96 (95% CI: 0.94–0.97). Neither group of patients demonstrated clinically relevant change in the alpha angle. Consequently, screening at time of skeletal of maturity would be an efficient means of identifying individuals for a possible cam deformity.

Highlights

Ganz et al [1] described femoroacetabular impingement (FAI) of the hip where there is pathological contact between the femur and acetabulum with two basic mechanisms: cam and pincer
Femoroacetabular impingement has been proposed as the principal pathomechanism leading to degenerative arthritis of the hip where bony deformities of the proximal femur and acetabulum lead to damage to the labral–chondral junction and eventual failure of the hip joint [6, 19]
Our current understanding of who is at risk of developing arthritis with FAI is still evolving [20]

Summary

Introduction

Ganz et al [1] described femoroacetabular impingement (FAI) of the hip where there is pathological contact between the femur and acetabulum with two basic mechanisms: cam and pincer. Some authors have proposed a developmental origin of the deformity by establishing a link between high activity levels during early adolescence influencing proximal femoral physeal growth leading to a higher prevalence of cam deformities FAI [12,13,14,15,16]. Another explanation could be reactive bone formation secondary to high activity or as part of the osteoarthritic process which would mean that the cam deformity could potentially evolve and change over time after the individual has reached skeletal maturity [17]

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