A new anterior cruciate ligament reconstruction fixation technique (quadrupled semitendinosus anterior cruciate ligament reconstruction with polyetheretherketone cage fixation)

Abstract

Fixation of the graft during anterior cruciate ligament reconstruction surgery has been the subject of numerous technical innovations but still remains a challenge. This article describes a novel technique of graft fixation for hamstring tendon reconstruction: the Cage For One system (Sacimex, Aix-en-Provence, France). The technique uses only the semitendinosus tendon, which is looped to create a 4-strand graft. Leaving the gracilis tendon intact probably reduces the loss of knee flexion strength. The graft is indirectly anchored into both tunnels with polyetheretherketone cages by use of polyethylene terephthalate tape strips. Both cages and strips are magnetic resonance imaging compatible and do not create artifacts. The tunnels are drilled by an outside-in method with minimal incisions. This type of fixation creates a 360° bone contact at 1.5 cm in each tunnel and is compatible with double-bundle reconstruction. This easy-to-use novel technique of fixation for anterior cruciate ligament reconstruction produces a strong 4-strand graft while harvesting only the semitendinosus tendon and leaving the gracilis tendon intact to reduce flexion strength loss and preserve rotatory stability of the knee. It creates an immediate solid fixation that is independent of graft integration in the early postoperative period, allowing the patient to start immediate rehabilitation without the use of a brace.

Figure 1

Semitendinosus graft preparation. To create a closed-loop 4-strand graft, the harvested semitendinosus tendon is wrapped around 2 poles that are part of the CFO traction device. These poles can slide on the traction device and are fixed at the desired graft length, which is 5.5 cm in male patients and 5 cm in female patients. Both extremities of the graft are tied together in a weaved (Pulvertaft) fashion and supplemented with sutures. Polyethylene terephthalate tape strips (arrows) are passed through each extremity of the looped tendon.

Figure 2

Tensioning of graft. Once tied, the graft is mounted on the CFO traction device. Pre-tensioning of the graft is performed with a screw tensioner and approximates 500 N. At this stage, the diameter and length of the graft are measured. A line is drawn at 1.5 cm of each extremity of the graft with a sterile marker. The lines will serve as references during arthroscopy to mark the articular exits of both tunnels.

Figure 3

Right distal femur during femoral tunnel preparation. A guide pin is inserted along the femoral guide from the superolateral aspect of the distal femur into the notch and deepened across the notch, behind the posterior cruciate ligament, until it is fixed in the medial condyle to prevent its displacement during drilling. (A) After drilling of the tunnel, a specific cannulated tap (red arrow) is used to prepare the bone for cage insertion. It should be noted that the articular extremity of the tunnel is not tapped to allow locking of the cage into the bone (blue arrow). (B) The cage is inserted into the femur until it stops against the untapped portion of the tunnel. (C) The graft is inserted into the tunnel in a retrograde fashion (black arrow) by pulling on the polyethylene terephthalate tape strips. (D) A PEEK locking screw (arrow) is inserted between the 2 polyethylene terephthalate tape strips to lock the strips against the cage.

Figure 4

Intraoperative view of right knee during tibial tunnel tapping. The patient is in the supine position with the knee flexed at 90°. The dedicated cannulated tap is slid along the fixed guide pin. The threaded part has a diameter of 10 mm, whereas the smooth part has a diameter that matches the graft. It should be noted that the smooth part has a length of 1.5 cm, corresponding to the amount of graft penetration into the bone. The tap is inserted into the tunnel until its tip can be visualized arthroscopically at the articular extremity of the tunnel, leaving 1.5 cm of untapped bone for graft integration.

Figure 5

Experimental demonstration of cage fixation into cadaveric femoral head. (A) The cage is fixed into the tunnel. It should be noted that only the outer portion of the tunnel was tapped. The articular extremity of the tunnel has a smaller diameter, matching the diameter of the graft. (B) The polyethylene terephthalate tape strips are passed into the cage, and a PEEK locking screw is screwed into the cage. It is important to place the locking screw between the 2 strips so that each strip is locked between the screw and the cage.

Figure 6

Endoscopic view of outer portion of femoral tunnel showing cage, locking screw, and polyethylene terephthalate (PET) tape strips. Each step of the cage fixation can be evaluated by direct visualization with the arthroscope. Adequate locking screw positioning can be verified to ensure complete locking of the polyethylene terephthalate tape strips into the cage.

Figure 7

Postoperative T1 sagittal magnetic resonance imaging view of right knee showing tibial tunnel and PEEK cage with its locking screw. The absence of artifact around the tibial cage and the locking screw should be noted. Semitendinosus graft shows a satisfactory diameter and sufficient tunnel penetration to allow integration.