Acetabular Labral Tear Type In Relation To Mechanism Of Hip Impingement

TitleAcetabular Labral Tear Type In Relation To Mechanism Of Hip Impingement
Publication TypeConference Paper
Year of Publication2011
AuthorsBotser I B, Martin DE, Domb BG
Conference NameInternational Society of Hip Arthroscopy (ISHA)
Date Published10/2011
Conference LocationParis, France

Summary: In 444 hips with hip impingement no correlation was found between labral tear type and bony morphology. Other findings suggest that labral tear pattern may be reflective of the degenerative process.

Background -
It has been postulated that bony morphology of femoral acetabular impingement may cause labral tears. Furthermore, it has been suggested that labral tear patterns may reflect the mechanism of impingement: cam-type impingement may preferentially damage the chondro-labral junction, while pincer-type impingement may cause intrasubstance tearing.

Purpose/hypothesis –
The hypothesis of the current study was that a relationship exists between bony morphology of cam and pincer femoroacetabular impingement (FAI) and acetabular labral pathology (chondro-labral detachment, intrasubstance damage or both). The purpose of the study was to examine this relationship.

Methods -
In the period between the years 2008 to 2011, 444 cases (421 patients) met our inclusion/exclusion criteria for the study. All patients had bony morphology of FAI - measured alpha angle >50° on Dunn view, positive crossover sign on AP-pelvic XR or both. Revision surgeries, history of fracture, previous hip disease or Tonnis arthritic grade >2 were the exclusion criteria of the study. Acetabular labral tear type was determined arthroscopically at the time of the surgical treatment for the FAI.
The cohort was divided into three groups: Group 1 – tears at the base of the labrum which created a chondro-labral detachment; Group 2 – intrasubstance damage, labral fraying, labral cysts or labral ossification; and Group 3 – combination of both.

Results -
A total of 206 cases (46.4%) fitted Group 1, 110 cases (24.7%) fitted group 2 and 128 cases (28.8%) fitted Group 3. There was an insignificant difference in the distribution of the three FAI types between the groups (p=0.21). Insignificant differences were found also for the crossover sign, the size of the ischial prominence, the head-neck offset and the alpha angle (MRI and Dunn view).
Significant differences between the groups were found regarding age (p=0.001), with group 1 the youngest and group 3 the oldest; acute onset of pain (p<0.01), lowest in group 1 and highest in group 3; and Tonnis arthritic grade (p=0.03), highest rate of Tonnis 0 in group 1 and lowest in group 3. Moreover, labral tear size was the only operative finding significantly different between the groups, with the smallest in group 1 and the highest in group 3 (p<0.0001).

Conclusions -
Correlation between labral pathology type and FAI type and morphology was not found. However, association to age, arthritic changes and labral tear size was found. Consequently, this association and its pattern may indicate a degeneration process rather than a morphological relationship.