Bc. Goss et al., CONTACT PRESSURE AND TENSION IN ANTERIOR CRUCIATE LIGAMENT GRAFTS SUBJECTED TO ROOF IMPINGEMENT DURING PASSIVE EXTENSION, Journal of orthopaedic research, 15(2), 1997, pp. 263-268
Contact between an anterior cruciate ligament graft and the intercondy
lar roof has been termed roof impingement. Grafts with impingement sus
tain permanent damage, and if the injury is extensive enough, then the
graft may fail, causing recurrent instability. This study evaluated t
wo mechanical factors that could be responsible for the graft injury a
ssociated with roof impingement: an increase in graft tension or eleva
ted pressures between the graft and the roof, or both. An anterior cru
ciate ligament reconstruction was performed using an Achilles tendon g
raft in five fresh-frozen cadaveric knees. Using a six-degree-of-freed
om load application system, the anterior displacement of the knee with
the native anterior cruciate ligament was restored in the reconstruct
ed knee at a flexion angle of 30 degrees and with an anterior force of
200 N applied. Pressure between the graft and intercondylar roof, gra
ft tension, and flexion angle were measured during passive knee extens
ion for three tibial tunnel placements (anterior, center, and posterio
r). Intercondylar roof impingement increased the contact pressure betw
een the graft and the roof but had no significant effect on graft tens
ion. Therefore, during passive knee extension, the contact pressure be
tween the anterior cruciate ligament graft and the intercondylar roof
is a more likely cause of graft damage than increased graft tension.