Abstract
Background“Killer turn” effect is a critical explanation for the recurrent posterior laxity following transtibial posterior cruciate ligament (PCL) reconstruction, which affected by the angle of the tibial tunnel. Meanwhile, excessive tunnel angle would have an adverse impact on the healing of tendon to bone. The purpose was to evaluate the theoretical optimal angle of the tibial tunnel in transtibial anatomic PCL reconstruction.MethodsThe measurements were performed on CT sagittal plane, including the thickness of cancellous bone (L1), the theoretical optimal angle of the tibial tunnel (TOA, which was measured between tibial plateau and the extension cord connecting the center of PCL insertion site with a point 5 mm superior from marrow cavity vertex), L2 - the distance from anterior tunnel aperture to anterior end of tibial plateau, L3 - the distance from anterior tunnel aperture to tibial tuberosity (lowest edge of patellar ligament attachment).ResultsThe value of TOA and L3 were 35.4 ± 7.9 ° and 26.8 ± 11.4 mm, respectively. L1 and L2 were higher in males than females (L1, P = 0.002; L2, P = 0.046). Regarding age, L1, TOA, L2 and L3 were higher in the 46–60 years group than 31–45 years group (P = 0.02, P = 0.001, P = 0.038, P = 0.032, respectively). With regard to height, L1 was lower in group I - < 1.66 m than group II - 1.66 to 1.75 m and group III - > 1.75 m (I v II, P = 0.015, I v III, P = 0.026). L2 was also lower in group I than group II and group III (I v II, P = 0.026, I v III, P = 0.006). TOA and L3 showed no significant differences among sex and height groups (P > 0.05).ConclusionsTOA (35.4 ° ± 7.9 °) and L3 (26.8 ± 11.4 mm) could be used as a reference for ideal tibial tunnel placement in transtibial anatomic PCL reconstruction, so as to prevent recurrent PCL laxity and ensure good graft healing. However, further clinical validation is needed.
Highlights
The transtibial tunnel technique has been commonly used for posterior cruciate ligament (PCL) reconstruction, in which the graft is pulled through and fixed in the tibial tunnel
We speculated that the optimal position of the graft within the tibial tunnel was the proximal vertex of the tibial marrow cavity, which improve the “killer turn” angulation and fixation strength and produce the satisfactory healing of tendon-to-bone
Previous studies have shown that clinical outcomes of PCL reconstruction were not so desirable compared with anterior cruciate ligament (ACL) reconstruction [2,3,4]
Summary
The transtibial tunnel technique has been commonly used for posterior cruciate ligament (PCL) reconstruction, in which the graft is pulled through and fixed in the tibial tunnel. Previous studies had shown that the fixation strength of interference screw was significantly related to local thickness of cortical bone [9, 10]. Several investigators had found in animal studies that the graft healing in cancellous-filled femoral tunnel was superior to that in marrow-dominated tibial tunnel [11,12,13]. Because of the tibial marrow cavity, the peripheral cancellous bone mass of PCL graft would decrease with the increases in tibial tunnel angle. We speculated that the optimal position of the graft within the tibial tunnel was the proximal vertex of the tibial marrow cavity, which improve the “killer turn” angulation and fixation strength and produce the satisfactory healing of tendon-to-bone. The theoretical optimal angle (TOA) is formed between the tibial tunnel through the proximal vertex of the tibial marrow cavity and tibial plateau
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