Posterior Cruciate Ligament: Tibial Tunnel   


- Tibial Tunnel:
    - saftey measures:
          - surgeons who do not perform this operation frequently should use flouroscopy for this tunnel;
          - apply Jacobs chuck for a preset distance on the guidewire to make it less likely for the wire to pass beyond posterior cortex (and injury NV structures);
          - consider making an extracapsular posterior medial incision which will allow surgeon's finger to be positioned between posterior capsule and N/V structures;
    - usually, the tibial tunnel will be anchored first, the graft pretensioned, and then the femoral tunnel will be achored;
    - cortical entry site:
          - incision: 5 cm longitudinal incision made below and medial to tibial tubercle;
          - some authors make this tunnel distal and medial to the ACL tibial tunnel site (approx 2 cm distal) when ACL reconstruction is required;
                  - other surgeons, will place the tunnel lateral to the tibial tubercle when ACL  reconstruction is required;
          - tunnel should begin well below tibial tubercle and is directed posteriorly so that it penetrates the posterior cortical surface 5-10 mm below joint line;
          - a steep incline may risk blowing out the posterior tibial wall;
    - articular entry site:
          - prior to drilling the tibial tunnel, the tibial insertion of the posterior capsule should be freed with a curette (use
                  postero-medial portal or the central portal);
          - tunnel should lie in center of PCL insertion, just lateral to midline in a depression between two tibial plateau surfaces (distal to level
                  of the articular surface at the distal portion of the posterior tibial edge);
          - note that the posterior cruciate ligament attaches 1-2 cm below the joint line;
                  - hence avoid the tendency to place the tunnel too close to the surface of the tibial plateau;
                  - for the ligament to function properly the tunnel must not exit too anteriorly;
          - hazards: popliteal artery injury:
                  - increasing knee flexion reduces, but does not completely eliminate, the risk of arterial injury during arthroscopic PCL reconstruction;
                          - maximum mean distances were noted at 100° of flexion in both the axial (9.9 mm) and sagittal (9.3 mm) planes;
                  - Proximity of the posterior cruciate ligament insertion to the popliteal artery as a function of the knee flexion angle.  Implications for posterior cruciate ligament reconstruction.  
    - it is important to smooth out the sharp edges of the tibial tunnel to facilitate graft passage and to prevent fraying of the graft fibers;
    - cautions:
          - if a concomitant ACL reconstruction is required
    - reference:
          A simplified approach to the tibial attachment of the posterior cruciate ligament.


Reducing the "killer turn" in posterior cruciate ligament reconstruction by fixation level and smoothing the tibial aperture.

 



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Wednesday, May 9, 2012 12:20 pm