Can combining femoral and acetabular morphology parameters improve the characterization of femoroacetabular impingement?

BACKGROUND: Femoroacetabular impingement (FAI) presupposes a dynamic interaction of the proximal femur and acetabulum producing clinical symptoms and chondrolabral damage. Currently, FAI classification is based on alpha angle and center-edge angle measurements in a single plane. However, acetabular and femoral version and neck-shaft angle also influence FAI. Furthermore, each of these parameters has a reciprocal interaction with the others; for example, a shallow acetabulum delays impingement of the femoral head with the acetabular rim. QUESTIONS/PURPOSES: We introduce the new parameter "omega zone," which combines five parameters into one: the alpha and center-edge angles, acetabular and femoral version, and neck-shaft angle. We sought to determine whether the omega zone could differentiate patients with FAI from (1) normal control subjects (alpha < 55°), but also from (2) control subjects with elevated alpha angles (≥ 55°). METHODS: We evaluated CT data of 20 hips of male patients with symptomatic cam-type FAI and of 35 male hips extracted from 110 anonymized CT scans for vascular diagnosis. We excluded hips with osteoarthritis, developmental dysplasia, or coxa profunda (center-edge angle 20°-45° on AP pelvic view or corresponding coronal CT views). With dedicated software, femoral and pelvic orientation was standardized; we tested the omega zone in four hip positions in three distinct groups: patients with cam-type FAI (alpha > 60°) and control subjects with normal (< 55°) and high alpha angles (≥ 55°). RESULTS: The omega zone was smaller in patients with cam-type FAI than normal control subjects (alpha angle < 55°) at 60° and 90° of flexion (mean, 12%; 95% confidence interval [CI], 7-17; p = 0.008; Cohen's d = 9%; 95% CI, 4-13; p = 0.003). Furthermore, the omega zone was smaller in all positions in patients with cam-type FAI than control subjects with high alpha angles (0° p = 0.017, 30° p = 0.004, 60° p = 0.004, 90° p = 0.007). In contrast, the omega zone did not differ between control subjects with normal or high alpha angles. In all hips, the omega zone decreased with flexion, corresponding to a decrease in remaining impingement-free motion with flexion. CONCLUSIONS: The omega zone visualizes and quantifies the interaction of the proximal femur and acetabulum. The omega zone differed between patients with cam-type FAI and control subjects with high alpha angles (≥ 55°), who could not be distinguished based on alpha angle alone. For hip-preserving surgery, it can help surgeons decide whether to address the femur, the acetabulum, or both.

What ape proximal femora tell us about femoroacetabular impingement: a comparison.

BACKGROUND: Human hip morphology is variable, and some variations (or hip morphotypes) such as coxa profunda and coxa recta (cam-type hip) are associated with femoroacetabular impingement and the development of osteoarthrosis. Currently, however, this variability is unexplained. A broader perspective with background information on the morphology of the proximal femur of nonhuman apes is lacking. Specifically, no studies exist of nonhuman ape femora that quantify concavity and its variability. QUESTIONS/PURPOSES: We hypothesized that, when compared with modern humans, the nonhuman apes would show (1) greater proximal femoral concavity; (2) less variability in concavity; and (3) less sexual dimorphism in proximal femoral morphology. METHODS: Using identical methods, we compared 10 morphological parameters in 375 human femora that are part of the Hamann-Todd collection at the Cleveland Museum of Natural History with 210 nonhuman ape femora that are part of the collection of the Royal Museum for Central Africa, Tervuren, Belgium, and the Muséum National d'Histoire Naturelle, Paris, France. RESULTS: The nonhuman apes have larger proximal femoral concavity than modern humans. This morphology is almost uniform without large variability or large differences neither between species nor between sexes. CONCLUSIONS: Variability is seen in human but not in nonhuman ape proximal femoral morphology. An evolutionary explanation can be that proximal femoral concavity is more important for the nonhuman apes, for example for climbing, than for modern humans, where a lack of concavity may be related to high loading of the hip, for example in running.

Evolution of the hip and pelvis.

Man's evolution features two unique developments: growing a huge brain and upright gait. Their combination makes the pelvis the most defining skeletal element to read human evolution. Recent revival in joint preserving hip surgery have brought to attention morphological variations of the human hip that appear similar to hips of extant mammals. In man, such variations can produce hip osteoarthrosis through motion. We reviewed the evolution of the hip and pelvis with special interest in morphology that can lead to motion induced osteoarthrosis in man. The combination of giving birth to big brained babies and walking upright has produced marked differences between the sexes in pelvis and hip morphology, each having their characteristic mode of hip impingement and osteoarthrosis.

Mammal hip morphology and function: coxa recta and coxa rotunda.

Using 15 parameters, we provide a systematic description of mammal proximal femoral morphology. We established two types of proximal femoral morphology, termed coxa recta and coxa rotunda, characterized by low versus high concavity of the head-neck junction. Concavity is a measure of the sphericity of the femoral head as it meets the femoral neck that can be quantified by angular measurements. We asked whether the parameter of concavity corresponds with the classification of mammal proximal femoral morphology based on coalesced versus separate ossification patterns and locomotor patterns. Statistical analysis demonstrated a distinction between coxa recta and coxa rotunda with significant differences between the two groups in all but 3 of the 15 parameters examined. We found the most discriminating measurement between mammal hips to be the concavity of the posterior head-neck junction (beta angle). Coxa recta (small concavity) and coxa rotunda (large concavity) relate to the ossification pattern seen in proximal femoral development, and species-specific patterns of locomotion. We interpret the two hip types to reflect optimization for strength (recta) versus mobility (rotunda). Conceptually, both hip types can be recognized in humans, where coxa recta can be related to the development of osteoarthritis.

Coxa recta, coxa profunda and abductor ratio: hip morphology variants compared in an arthroplasty and control population.

Morphology variants of the hip such as coxa recta (aspherical femoral head and/or reduced head-neck concavity) or coxa profunda (overcoverage, or "deep" socket) are associated with cam and pincer impingement respectively, and may ultimately lead to coxarthrosis. Several population studies have documented the prevalence of hip morphotypes, but few studies have examined this prevalence in total hip arthroplasty (THA) patients, or persons without hip symptoms or signs.
We reviewed whether coxa recta and profunda morphotypes were more prevalent in THA patients compared to normal controls. Further, we explored differences in hip abductor mechanism related to hip morphology.
We examined 113 THA patients and 83 normal controls with anteroposterior pelvic and lateral hip radiographs. Coxa recta and profunda were classified with alpha and lateral CE-angle, respectively. The abductor ratio (AR) was measured on AP pelvic radiographs.
Both coxa recta and profunda were more prevalent in THA patients than normal controls (coxa recta: male 42% vs 8%, female 15% vs 5%, respectively and coxa profunda: male 20% vs 1%, female 19% vs 6% respectively). AR was higher in females than males, both in THA patients (1.66 vs 1.47) and normal controls (1.68 vs 1.57). Coxa profunda was associated with a lower AR (1.54 vs 1.61).
The higher prevalence of coxa recta and profunda in arthroplasty patients supports the theory of a role of these morphotypes in the development of coxarthrosis. The higher AR in females signifies the need for increased abductor work. Coxa profunda may be an adaptation to lower the AR.

[A bodybuilder with an injury]. / Een bodybuilder met een blessure.

A bodybuilder presented to the emergency room with pain in his upper limb after doing some bench presses. Examination of the right arm showed a haematoma and muscle weakness. An MRI of the chest and upper limb showed a rupture of the tendon of the pectoralis major muscle.