Thick Graft Versus Double-Bundle Technique on Posterior Cruciate Ligament Reconstruction: Experimental Biomechanical Study with Cadavers

Abstract

Objective To evaluate the biomechanical effect of graft thickness compared with the double-bundle technique on posterior cruciate ligament (PCL) reconstruction in human cadaveric knees. Methods A total of 9 human cadaveric knees were tested in 5 conditions: intact knee (INT); single-bundle reconstruction with a 10-mm quadriceps tendon (SB); double-bundle reconstruction with a 10 mm-quadriceps tendon for the anterolateral bundle and a 7-mm doubled semitendinosus tendon for the posteromedial bundle (DB); single-bundle reconstruction with a 10-mm quadriceps tendon plus a 7-mm doubled semitendinosus tendon (SBT); and PCL-deficient (NoPCL). The posterior tibial translation (PTT) was measured in response to a 134-N posterior tibial load at 0 ^∘ , 30 ^∘ , 60 ^∘ e 90 ^∘ of knee flexion. Results The PTT values of the DB and SBT techniques were always significantly lower (better stability) than those of the SB technique. The PTT values of the SBT technique were significantly lower than those of the DB technique at 60 ^∘ ( p = 0.005) and 90 ^∘ ( p = 0.001). Conclusions Graft enlargement improves knee stability in isolated PCL reconstructions, whereas the graft division in the two-bundle technique worsens this stability at 60 ^∘ and 90 ^∘ of knee flexion. The findings of the present study suggest that knee stability in PCL reconstructions may be improved with the use of thicker grafts in the SB technique rather than performing the DB technique.

Keywords: biomechanical phenomena; cadaver; knee injuries; posterior cruciate ligament; posterior cruciate ligament reconstruction.

Fig. 1

Knee positioned at 90° of flexion, fixated to the testing machine. The tibia remained horizontal, with the anterior margin facing the ground. The machine performed the elevation or descent of the femur in relation to the tibia, which corresponded, respectively, to the movement of the anterior and posterior drawers.

Fig. 2

Sequence of testing conditions.

Fig. 3

Graft tensioning monitored by the dynamometer.

Fig. 4

Tibial fixation device. The polyester threads from the graft were locked between two platelets.

Fig. 5

Posterior tibial translation (PTT) of all testing conditions at each flexion angle: intact posterior cruciate ligament (PCL) (blue line); injured PCL (red line); single-bundle reconstruction with a 10-mm quadriceps tendon (green line); double-bundle reconstruction with a 10-mm quadriceps tendon for the anterolateral bundle and a 7-mm doubled semitendinosus tendon for the posteromedial bundle (brown line); single-bundle reconstruction with a 10-mm quadriceps tendon plus a 7-mm doubled semitendinosus tendon (black line).

Fig. 1

Joelho posicionado a 90° de flexão, fixado à máquina de teste. A tíbia permaneceu horizontalmente com a margem anterior voltada para o solo. A máquina realizava a elevação ou descida do fêmur em relação à tíbia, correspondendo, respectivamente, ao movimento de gaveta anterior e posterior.

Fig. 2

Sequência das condições de teste.

Fig. 3

Tensionamento do enxerto monitorado pelo dinamômetro.

Fig. 4

O dispositivo de fixação tibial. Os fios de poliéster do enxerto foram bloqueados entre duas plaquetas.

Fig. 5

O limite de deslocamento posterior da tíbia (LDPT) de todas as condições de teste a cada ângulo de flexão: ligamento cruzado posterior (LCP) intacto (linha azul); LCP lesionado (linha vermelha); reconstrução de feixe único com tendão do quadríceps de 10 mm (linha verde); reconstrução de duplo feixe com um tendão do quadríceps de 10 mm para o feixe anterolateral e um feixe de 7mm do semitendíneo duplo para o feixe póstero-medial (linha marrom); reconstrução de feixe único com um tendão do quadríceps de 10 mm mais um feixe de 7mm do semitendíneo duplo (linha preta).