Size and shape of the lunate surface in different types of pincer impingement: theoretical implications for surgical therapy.

Steppacher, Simon Damian; Lerch, T D; Gharanizadeh, K; Liechti, E F; Werlen, S F; Puls, M; Tannast, Moritz; Siebenrock, Klaus-Arno (2014). Size and shape of the lunate surface in different types of pincer impingement: theoretical implications for surgical therapy. Osteoarthritis and cartilage, 22(7), pp. 951-958. Elsevier 10.1016/j.joca.2014.05.010

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Acetabular rim trimming is indicated in pincer hips with an oversized lunate surface but could result in a critically decreased size of the lunate surface in pincer hips with acetabular malorientation. There is a lack of detailed three-dimensional anatomy of lunate surface in pincer hips. Therefore, we questioned how does (1) size and (2) shape of the lunate surface differ among hips with different types of pincer impingement?


We retrospectively compared size and shape of the lunate surface between acetabular retroversion (48 hips), deep acetabulum (34 hips), protrusio acetabuli (seven hips), normal acetabuli (30 hips), and hip dysplasia (45 hips). Using magnetic resonance imaging (MRI) arthrography with radial slices we measured size in percentage of the femoral head coverage and shape using the outer (inner) center-edge angles and width of lunate surface.


Hips with retroversion had a decreased size and deep hips had normal size of the lunate surface. Both had a normal shape of the outer acetabular rim. Protrusio hips had an increased size and a prominent outer acetabular rim. In all three types of pincer hips the acetabular fossa was increased.


Size and shape of the lunate surface differs substantially among different types of pincer impingement. In contrast to hips with protrusio acetabuli, retroverted and deep hips do not have an increased size of the lunate surface. Acetabular rim trimming in retroverted and deep hips should be performed with caution. Based on our results, acetabular reorientation would theoretically be the treatment of choice in retroverted hips.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > Department of Orthopaedic, Plastic and Hand Surgery (DOPH) > Clinic of Orthopaedic Surgery

UniBE Contributor:

Steppacher, Simon Damian; Tannast, Moritz and Siebenrock, Klaus-Arno


600 Technology > 610 Medicine & health








Stefanie Zurbuchen

Date Deposited:

11 Feb 2015 10:59

Last Modified:

09 Nov 2015 11:27

Publisher DOI:


PubMed ID:


Uncontrolled Keywords:

Coxa profunda, Hip, Joint preserving surgery, Lunate surface, Pincer impingement, Protrusio, Retroversion




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