Ganz R, Leunig M, Leunig-Ganz K, et al. The etiology of osteoarthritis of the hip: an integrated mechanical concept

University of Berne, Berne, Switzerland.
Clinical Orthopaedics and Related Research (Impact Factor: 2.88). 03/2008; 466(2):264-72.
Source: PubMed

ABSTRACT The etiology of osteoarthritis of the hip has long been considered secondary (eg, to congenital or developmental deformities) or primary (presuming some underlying abnormality of articular cartilage). Recent information supports a hypothesis that so-called primary osteoarthritis is also secondary to subtle developmental abnormalities and the mechanism in these cases is femoroacetabular impingement rather than excessive contact stress. The most frequent location for femoroacetabular impingement is the anterosuperior rim area and the most critical motion is internal rotation of the hip in 90 degrees flexion. Two types of femoroacetabular impingement have been identified. Cam-type femoroacetabular impingement, more prevalent in young male patients, is caused by an offset pathomorphology between head and neck and produces an outside-in delamination of the acetabulum. Pincer-type femoroacetabular impingement, more prevalent in middle-aged women, is produced by a more linear impact between a local (retroversion of the acetabulum) or general overcoverage (coxa profunda/protrusio) of the acetabulum. The damage pattern is more restricted to the rim and the process of joint degeneration is slower. Most hips, however, show a mixed femoroacetabular impingement pattern with cam predominance. Surgical attempts to restore normal anatomy to avoid femoroacetabular impingement should be performed in the early stage before major cartilage damage is present. LEVEL OF EVIDENCE: Level V, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

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Available from: Michael Leunig, Dec 25, 2014
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    • "d for medical purposes ( Bullough et al . , 1973 ; Müller - Gerbl et al . , 1993 ; Feugier et al . , 1997 ; Witte et al . , 1997 ; Thompson et al . , 2000 ; Gupta et al . , 2001 ; Varodompun et al . , 2002 ; Lavy et al . , 2003 ; Leunig et al . , 2003 ; Zilber et al . , 2004 ; Govsa et al . , 2005 ; Sampson , 2005 ; Tallroth and Lepist€ o , 2006 ; Ganz et al . , 2008 ; Vandenbussche et al . , 2008 ; K€ ohnlein et al . , 2009 ; Krebs et al . , 2009 ; Pollard et al . , 2010 ; Nakahara et al . , 2011 ; Zeng et al . , 2012 ) . Other studies have examined load trans - fer across the hip bone and the hip joint ( Eckstein et al . , 1994 ; Dalstra and Huiskes , 1995 ; Lazennec et al . , 1997 ; Witte et al ."
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    ABSTRACT: The description of acetabular shape variation among primates is essential for our understanding of the locomotor behaviour and ecology of both extant and fossil species. In this study, we use two-dimensional geometric morphometrics to examine variation in acetabular shape in human and non-human primates and to determine the degree to which it co-varies with locomotor behaviour, while taking both intra and inter-specific variation into account. To these ends, we examined the acetabulum of 303 left hip bones of 27 extant genera of primates (including humans) with different locomotor behaviours. After accounting for shape variation due to sex, size, and phylogeny, the results confirm that acetabular shape varies significantly across locomotor groups. The two most differentiated locomotor groups are leapers and slow-climbing quadrupeds, which exhibit a unique acetabular shape. Furthermore, the acetabulum of humans differed significantly from all other groups, while no significant differences existed between chimpanzees and gorillas. The most noticeable differences are detected in both cranial and dorsal areas and around the acetabular horns. This variation in acetabular morphology may have biomechanical implications at the level of the hip joint, potentially determining joint range motion and load distribution during locomotion. Given the increasing number of published studies on fossil pelves, our results are widely applicable to fossil analyses, with critical implications for paleoanthropological analyses about the complex locomotor behaviour of fossil specimens and their classification into locomotor groups, which may enhance our understanding of their ecological habits. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Journal of Human Evolution 04/2015; 83. DOI:10.1016/j.jhevol.2015.03.007 · 3.87 Impact Factor
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    • "In this study , we have evaluated the FeMorph software ' s ability to plan cam corrective surgery and estimate the likely improvement in RoM . In the CT data sample , both alpha angle and HNRs indicated that an abnormally large proportion of cam - type femurs were present , when compared to the proposed overall prevalence of FAI of 15% ( Ganz et al . 2008 ) . In addition , when comparing the diagnostic ability of the two measures , a disparity with regard to the detection of cam - type femurs was seen . This is illustrated by the high proportion ( 48% ) of femurs categorised as cam - type by the maximum alpha angle , but normal with regard to HNRs . This may , in part , be due to the nat"
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    ABSTRACT: Impingement resulting from a cam deformity may cause pain, limit the hip joint range of motion (RoM) and lead to osteoarthritis. We have previously developed FeMorph software to quantify and plan corrective surgery and predict hip RoM post surgery. This study aimed to validate the software and evaluate the influence of the acetabular labrum on hip RoM. Computed tomography data from 92 femur-pelvis pairs were analysed in conjunction with the inter/intra-observer reliability. Four cadaveric hips were dissected, and the three-dimensional (3D) shape and size of the acetabular labrum for these hips was obtained using laser scan. The influence of the acetabular labrum in the RoM and subsequent planning for corrective surgery were then evaluated in cadavers for models with and without a labrum, and used as a first step towards validation of FeMorph RoM prediction. FeMorph was successfully used to model cam deformities and plan corrective surgery. Three-dimensional alpha angles were reduced to below 50° after virtual surgery without an excessive reduction in femoral neck cross-sectional area, which could increase fracture risk. A mean increase of 8° ± 2° in permitted internal rotation was observed during impingement testing following removal of the labrum. FeMorph provides a reliable and useful method to model and plan cam deformity correction. This study indicates that the presence of the labrum is responsible for a substantial decrease in permitted internal rotation at the hip joint. This has implications for surgical planning models which often only account for bony impingement.
    Computer Methods in Biomechanics and Biomedical Engineering 12/2014; DOI:10.1080/10255842.2014.986654 · 1.79 Impact Factor
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    • "Hip morphology variants may influence the development of osteoarthritis (OA) (Ganz et al. 2008). Femoral morphology variants may be best characterized by concavity, a compound measure determined by the sphericity and offset of the femoral head (determined from relative neck width and femoral head position on the neck). "
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    ABSTRACT: Background and purpose The alpha angle is the most used measurement to classify concavity of the femoral head-neck junction. It is not only used for treatment decisions for hip impingement, but also in cohort studies relating hip morphology and osteoarthritis. Alpha angle measurement requires identification of the femoral neck axis, the definition of which may vary between studies. The original “3-point method” uses 1 single point to construct the femoral neck axis, whereas the “anatomic method” uses multiple points and attempts to define the true anatomic neck axis. Depending on the method used, the alpha angle may or may not account for other morphological characteristics such as head-neck offset. Methods We compared 2 methods of alpha angle measurement (termed “anatomic” and “3-point”) in 59 cadaver femora and 83 cross-table lateral radiographs of asymptomatic subjects. Results were compared using Bland-Altman plots. Results Discrepancies of up to 13 degrees were seen between the methods. The 3-point method had an “equalizing effect” by disregarding femoral head position relative to the neck: in femora with high alpha angle, it resulted in lower values than anatomic measurement, and vice versa in femora with low alpha angles. Using the anatomic method, we derived a reference interval for the alpha angle in normal hips in the general population of 30–66 degrees. Interpretation We recommend the anatomic method because it also reflects the position of the femoral head on the neck. Consensus and standardization of technique of alpha angle measurement is warranted, not only for planar measurements but also for CT or MRI-based measurements.
    Acta Orthopaedica 04/2014; 85(2):147-51. DOI:10.3109/17453674.2014.899841 · 2.45 Impact Factor
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