A biomechanical basis for tears of the human acetabular labrum.
OBJECTIVE
Acetabular labral tears predominantly affect young patients and are a source of hip pain in the athlete. Four causes of the initiation of labral tears have been proposed; trauma, hypolaxity of the anterior capsule, dysplasia and bony impingement. A further cause could be reduced biomechanical properties in the area most susceptible to tears. However, no work has defined these properties.


METHODS
32 compressive and 32 tensile test samples were harvested from fresh-frozen cadaveric acetabula. The labrum was divided into eight areas to allow comparison around its circumference. Semiconfined compressive testing and tensile testing were performed at a displacement rate of 10 mm/min in a controlled environment of 100% humidity at 37 (SD 1) degrees C.


METHODS
Cadaveric study.


RESULTS
The mean compressive stiffness was 31.75 (SD 16.7) MPa, and the mean tensile elastic modulus was 24.7 (SD 10.8) MPa. The anterosuperior region had a significantly lower compressive elastic modulus than either of the posterior quadrants (p<0.05) and a significantly lower tensile modulus to the anterioinferior area (p<0.05).


CONCLUSIONS
The biomechanical properties in the anterosuperior region may be a contributing factor to the initiation of labral tears.
Smith
C D
CD
Department of Bioengineering, Imperial College London, Royal School of Mines, South Kensington Campus, London, UK. drcs1@doctors.net.uk
Masouros
S
S
Hill
A M
AM
Amis
A A
AA
Bull
A M J
AM
D000077:Acetabulum / Q000293:injuries*; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002102:Cadaver; D002358:Cartilage, Articular / Q000293:injuries*; D055119:Elastic Modulus; D025981:Hip Injuries / Q000209:etiology*; D006801:Humans; D012421:Rupture; D013718:Tensile Strength / Q000502:physiology