Penetration depth method—novel real‐time strategy for evaluating femoroacetabular impingement

Abstract

We introduce a new method for computerized real-time evaluation of femoroacetabular impingement (FAI). In contrast to previously presented stress analyses, this method is based on two types of predictions of penetration depths for two rotating bodies: curvilinear and radial penetration depth. This intuitive method allows the analysis of both bony and soft tissue structures (such as cartilage and acetabular labrum) in real time. Characteristic penetration depth patterns were found for different subtypes of FAI, such as cam and pincer pathologies. In addition, correlation between the penetration depths (estimated by applying this method) and the existing contact stresses (estimated by applying the finite element method) of various hip morphologies were found. A strong correlation with predicted stress values existed, with a mean correlation coefficient of 0.91 for the curvilinear and 0.80 for the radial penetration method. The results show that the penetration depth method is a promising, fast, and accurate method for quantification and diagnosis of FAI. ß

A method for three-dimensional evaluation and computer aided treatment of femoroacetabular impingement

“…Once the morphology of the proximal femur and the size and location of a possible cam lesion were defined, the potential presence of a pincer-type lesion at the acetabular side was evaluated using an approach similar to the penetration depth method described by Arbabi et al [4].…”

“…Cam-type prominences appear to have a particularly destructive effect on acetabular cartilage as they have the potential to intrude into the hip joint and thereby increase von Mises stresses and contact pressure at the labrum-cartilage junction and at the subchondral bone of the acetabulum, with subsequent delamination and tearing of the acetabular cartilage. Finite element analysis has provided evidence that in cam-type lesions this mechanism operates even during normal everyday activities, such as sitting and standing [3,4].…”

Can Combining Femoral and Acetabular Morphology Parameters Improve the Characterization of Femoroacetabular Impingement?

“…This is analogous to the omega zone but in a single plane. Furthermore, hip motion in FAI was studied with virtual hip models by Arbabi et al [2]. In that study, all morphology parameters were kept constant; only alpha and CE angle were varied to simulate dysplasia, cam-, pincer-, and combined-type morphology.…”

“…In that study, all morphology parameters were kept constant; only alpha and CE angle were varied to simulate dysplasia, cam-, pincer-, and combined-type morphology. Collision detection algorithms demonstrated two types of penetration of the two rotating bodies (the hip components) with hip motion, named radial and curvilinear, for cam-and pincertype morphology, respectively [2]. Perhaps, for the clinician, the omega zone has the advantage of being more visual.…”

Finite Element Analysis and Validation of Hip Joints With the Main Types of Femoroacetabular Impingement

“…According to Arbabi et al, it is now recognized as the leading pathomechanism that causes "primary" osteoarthritis [13]. impingement models using existing healthy bone models, (2) develop anatomically accurate hip models using the bones experiencing femoroacetabular impingement, (3) validate the models using experimental data found in literature, and (4) compare the stresses found in the acetabula of the models.…”