TY  - JOUR
T1  - Early Tension Loss in an Anterior Cruciate Ligament GraftA Cadaver Study of Four Tibial Fixation Devices
AU  - Grover, Dustin M.
AU  - Howell, Stephen M.
AU  - Hull, Maury L.
Y1  - 2005/02/01
N1  - 10.2106/JBJS.C.01527
JO  - The Journal of Bone & Joint Surgery
SP  - 381
EP  - 390
VL  - 87
IS  - 2
N2  - Background: The tensile force applied to an anterior cruciate
ligament graft determines the maximal anterior translation; however, it is
unknown whether the tensile force is transferred to the intra-articular
portion of the graft and whether the intra-articular tension and maximal
anterior translation are maintained shortly after ligament reconstruction.Methods: Ten cadaveric knees were reconstructed with a double-looped
tendon graft. The graft was looped through a femoral fixation transducer that
measured the resultant force on the proximal end of the graft. A pneumatic
cylinder applied a tensile force of 110 N to the graft exiting the tibial
tunnel with the knee in full extension. The graft was fixed sequentially with
four tibial fixation devices (a spiked metal washer, double staples, a
bioabsorbable interference screw, and a WasherLoc). Three cyclic loading
treatments designed to conservatively load the graft and its fixation were
applied.Results: The combined loss in intra-articular graft tension from
friction, insertion of the tibial fixation device, and three cyclic loading
treatments was 50% for the spiked washer (p = 0.0004), 100% for the double
staples (p < 0.0001), 64% for the interference screw (p = 0.0001), and 56%
for the WasherLoc (p < 0.0001). The tension loss caused an increase in the
maximal anterior translation from that of the intact knee of 2.0 mm for the
spiked washer (p = 0.005), 7.8 mm for the double staples (p < 0.0001), 2.7
mm for the interference screw (p = 0.001), and 2.1 mm for the WasherLoc (p
< 0.0001).Conclusions: The tensile force applied to a soft-tissue anterior
cruciate ligament graft is not transferred intra-articularly and is not
maintained during graft fixation. The loss in tension is caused by friction in
the tibial tunnel and wrapping the graft around the shank of the screw of the
spiked washer, insertion of the tibial fixation device, and cyclical loading
of the knee. The amount of tension loss is sufficient to increase the maximal
anterior translation.Clinical Relevance: Surgeons should pay close attention to the
technique for inserting the tibial fixation device as this study supports the
assumption that this step induces the greatest change and variability in the
intra-articular tension and maximal anterior translation in the knee
reconstructed with a double-looped tendon graft. Cyclically loading the knee
causes a further loss in intra-articular tension and an increase in the
maximal anterior translation, which can be reduced by the use of fixation
devices that resist lengthening at the site of fixation and by limiting cyclic
loading of the knee.
SN  - 0021-9355
M3  - doi: 10.2106/JBJS.C.01527
UR  - http://dx.doi.org/10.2106/JBJS.C.01527
ER  -