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Development of the FAI module

There is two different types of FAI:
the Pincer deformity (characterized by excessively overreaching acetabular edges and/or retrotorsion of the acetabular socket) and the Cam deformity (protrusion/bumps at the femoral head/proximal femur junction as well as offset disorder and asphericity of the femoral head), often to be found in combination.
Our new FAI module will assist you with precise measuring and assessment of all FAI types, using various forms of x-ray images (for our users, the correct procedure is described in our x-ray and scaling manual):

fai img1 en Pelvis overview (anterior-posterior)
After defining the hip joint center and the ischial bone tangent (as a reference line), you have two options that can be performed and combined as needed:
1) By drawing the outlines of the anterior and posterior acetabular edges (“cross-over sign“ in case those outlines intersect), you can determine and illustrate an acetabular retroversion or an overreaching acetabular edge (often anterolateral). This can indicate either dysplasia or a Pincer deformity.
2) By drawing the lateral center edge angle according to Wiberg (CE angle), you can also assess a Pincer deformity or measure dysplasia if the angle exceeds or falls short of the normal values.

fai img2 enFalse profile (“faux” profile) x-ray
A faux profile x-ray is always recommended. In case of a suspected cross-over sign on the pelvis overview, you can assess the various types of the Pincer deformity by measuring the anterior CE angle and assessing the dorsal joint cavity widths (e.g. a posterior impingement due to a prominent posterior edge).

Both the Pincer deformity as well as the anterolateral acetabular roof (for the purpose of dysplasia diagnostics) can be measured using the anterior CE angle (VCA angle).
Axial x-ray (e.g. cross-table or Rippstein)
An axial recording is recommended to assess the asphericity of the femoral head (Cam deformity). For this purpose, alpha angle and femoral head-neck offset are determined. In principle, you can conclusively measure this angle in all hip rotation positions.

The standard planes are pelvis overview (pistolgrip deformity) as well as Lauenstein and Rippstein images.
The alpha angle is measured by only 3 mouse clicks, between the femoral neck axis as well as the line between the hip joint center and the point of the head outline leaving the spericity. At the same time, the femoral head-neck offset is determined by means of two parallel lines between the latter point and the tangent of the anterior femoral head outline.
A deviation from the normal values of both the alpha angle and/or the femoral head-neck offset indicate a Cam deformity.

After performing all measurements, you can proceed to the resection, therefore documenting all necessary steps pre and post operatively for quality management purposes, as well as for visualization during surgery. mediCAD further allows you to use all functions and options you are accustomed to.
Combining the FAI module with other modules, e.g. in order to insert hip implants or perform a leg length correction, is also possible at any time.

The FAI module was developed in close cooperation with Dr. med. Wolfgang Zinser (St. Vinzenz Hospital, Dinslaken).
Please contact our This email address is being protected from spambots. You need JavaScript enabled to view it. team for further details.

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