Dl. Johnson et al., ARTICULAR-CARTILAGE CHANGES SEEN WITH MAGNETIC-RESONANCE IMAGING-DETECTED BONE BRUISES ASSOCIATED WITH ACUTE ANTERIOR CRUCIATE LIGAMENT RUPTURE, American journal of sports medicine, 26(3), 1998, pp. 409-414
Occult osteochondral lesions (bone bruises) have been documented on ma
gnetic resonance images in more than 80% of patients sustaining acute
anterior cruciate ligament ruptures. Despite the high prevalence of th
ese lesions, little is known about the histologic changes in the adjac
ent articular cartilage. Ten patients with acute anterior cruciate lig
ament ruptures who had a preoperatively documented (by magnetic resona
nce imaging) geographic bone bruise at the sulcus terminalis on the la
teral femoral condyle underwent a 3-mm diameter trephine biopsy of the
articular cartilage and subchondral bone overlying the bone bruise at
the time of anterior cruciate ligament reconstruction. Biopsy samples
of the articular cartilage and subchondral bone were stained with hem
atoxylin and eosin and toluidine blue. All patients had significant ar
throscopic and histologic articular cartilage irregularity in the area
overlying the bone bruise. Arthroscopic findings of the articular car
tilage included softening (dimpling), fissuring, or overt chondral fra
cture. Histologic examination revealed degeneration of the chondrocyte
s and loss of toluidine blue staining in the articular cartilage (loss
of proteoglycan). There was necrosis of osteocytes in the subchondral
bone, and empty lacuna were visible. This study defines the exact his
tologic changes of the articular cartilage overlying a geographic bone
bruise secondary to an acute anterior cruciate ligament tear. Our fin
dings suggest that a geographic bone bruise found on magnetic resonanc
e imaging indicates substantial damage to normal articular cartilage h
omeostasis.