Philippe Calas, M.D., Nicolas Dorval, M.D., Anthony Bloch, M.D., Jean-Noël Argenson, M.D., Ph.D., and Sébastien Parratte, M.D., Ph.D.

Transcription

1 A New Anterior Cruciate Ligament Reconstruction Fixation Technique (Quadrupled Semitendinosus Anterior Cruciate Ligament Reconstruction With Polyetheretherketone Cage Fixation) Philippe Calas, M.D., Nicolas Dorval, M.D., Anthony Bloch, M.D., Jean-Noël Argenson, M.D., Ph.D., and Sébastien Parratte, M.D., Ph.D. 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. Anterior cruciate ligament (ACL) reconstruction surgery has proven its efficacy in restoring nearnormal knee stability. Hamstring autografts are commonly used and seem to reduce knee pain when compared with bone-to-bone patellar autograft. 1,2 Most From Clinique Axium (P.C., A.B.), Aix-en-Provence, France; Centre de Santé et de Services Sociaux de la Région de Thetford (N.D.), Thetford Mines, Quebec, Canada; and Assistance Publique des Hôpitaux de Marseille (APHM), Center for Arthritis Surgery, Hopital Sainte-Marguerite, Aix-Marseille University (J-N.A., S.P.), Marseille, France. The authors report that they have no conflicts of interest in the authorship and publication of this article. Received November 2, 2011; accepted January 5, Address correspondence to Sébastien Parratte, M.D., Ph.D., Institute of Movement Sciences, GIBOC Team, ISM-UMR 6233 CNRS, APHM, Center for Arthritis Surgery, Hôpital Sainte-Marguerite, 13009, Marseille, France. sebastien@parratte.fr 2012 by the Arthroscopy Association of North America. Open access under CC BY-NC-ND license /11723 doi: /j.eats hamstring ACL reconstructions use the semitendinosus and gracilis tendons. Harvesting these 2 tendons results in a force deficit in the knee flexors; this deficit can be reduced by harvesting only the semitendinosus tendon. 3 This might also have an advantage in terms of rotatory stability of the knee. ACL reconstruction with quadrupled semitendinosus has shown excellent results. 3 Different technologies have been developed in recent years to obtain a solid and reproducible anchoring of the graft, but this remains a challenge. 4-9 This study describes the Cage For One (CFO) system (Sacimex, Aix-en-Provence, France), which is a 4-strand semitendinosus graft fixed indirectly in screwed polyetheretherketone (PEEK) cages by polyethylene terephthalate tape strips at the femoral and tibial levels. Both tunnels are drilled by an outside-in method with minimal incisions. The name Cage For One summarizes the key points of the technique: Cage for the use of an original system using a cage as a fixation device and For One because only the semitendinosus is Arthroscopy Techniques, Vol 1, No 1 (September), 2012: pp e47-e52 e47

2 e48 P. CALAS ET AL. harvested; moreover, For can also be understood as Four in relation to the 4-strand graft created with the semitendinosus. SURGICAL TECHNIQUE FIGURE 1. Semitendinosus graft preparation. To create a closedloop 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. Under general or regional anesthesia, the patient is placed in the supine position with the knee flexed at 90 or, alternatively, the leg is placed in a leg holder and flexed freely at the extremity of the table. The incision is centered 7 or 8 cm distal to the inferior pole of the patella depending on the patient s height and 5 cm medial to the tibial crest. A 3-cm oblique incision is used to lessen the risk of injury to the infrapatellar branch of the saphenous nerve. The semitendinosus tendon is then harvested in a standard fashion, with care taken to obtain the longest graft possible. The tendon is freed from the muscle remnants left by the tendon stripper while still attached to the tibia. The tibial insertion is cut to maximize tendon length. The fascia overlying the pes anserinus is then closed with absorbable sutures. Once harvested, the semitendinosus tendon is wrapped around 2 poles that are distanced apart by 5 cm in female patients and 5.5 cm in male patients. With a No. 11 blade, a buttonhole is created in the largest extremity of the graft, and the finest extremity is passed through the hole in a weaved (Pulvertaft) fashion. The length of the graft should be long enough to allow the tendon to be wrapped 2 times around the poles, thus creating a 4-strand graft (Fig 1). Two polyethylene terephthalate strips are passed in the tendon loop at each extremity. They are 6.5 mm wide and can resist a mean traction force of 650 N. 5 The tendon is fixed to itself with No. 2 absorbable sutures. The tendon is then manipulated by use of the 2 strips. It is mounted and fixed on the CFO traction device with clamps (Fig 2). Tensioning is performed manually with a screw tensioner and should approximate 500 N. The graft usually increases its length by 5 mm at the beginning of the tensioning procedure and by 7 or 8 mm after 10 to 15 minutes on the traction table. During the arthroscopic portion of the procedure, all compartments are inspected and ACL rupture is confirmed. Meniscus surgery is performed whenever needed. The femoral origin of the ACL is debrided with a shaver, but we do not systematically perform notchplasty. The femoral tunnel is prepared first. A dedicated drill guide is positioned in the superolateral 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.

3 GRAFT FIXATION IN ACL RECONSTRUCTION e49 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. aspect of the femoral notch, at the 10:30 clock position for right knees or 1:30 for left knees. The skin is incised longitudinally over the lateral aspect of the distal femur, and the incision is deepened directly to the bone. It measures around 1 cm. A guide pin is inserted along the 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. We start with a 7-mm bit to drill the whole length of the tunnel. A dilatator sized according to the graft diameter is then used to compress the trabecular bone around the tunnel. The wire is taken out, and the articular extremity of the tunnel is cleaned with the shaver. The final length of the tunnel is measured. The length usually approximates between 40 and 50 mm. A 10-mm tap is passed along the outer portion of the tunnel to prepare the femur for cage insertion. The inner 1.5 cm of the tunnel is not tapped because it will become the area of integration for the graft. This is a crucial step because the tapping will determine the cage position. The PEEK cage is screwed in, and because it is not self-tapping, it will stop automatically where the tapping was ended previously. All cages are 15 mm long and have a diameter of 10 mm (Figs 3 and 4). This procedure is repeated at the tibial level. The incision used to harvest the semitendinosus is also used to prepare the tibial tunnel. The tibial insertion of the ACL is cleaned with the shaver. The drill guide is placed so that the guide pin reaches the articulation close to the extremity of the lateral meniscus anterior horn. The pin is inserted until it is fixed in the femur so that it does not come out during drilling. The tibia is then drilled and tapped by the same technique used during femoral tunnel preparation. We do not insert the tibial cage at this stage because we used the tibial tunnel to insert the 4-strand graft. Alternatively, the graft can be inserted through the anteromedial portal. 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.

4 e50 P. CALAS ET AL. 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. The graft is taken off the traction table and measured. We mark a point at 1.5 cm of each graft extremity with a sterile marker to obtain a visible arthroscopic reference of the graft insertion in both tunnels. A shuttle relay is used to carefully pass the strips into both tunnels in a retrograde manner. The strips are pulled through the femoral incision until the graft blocks against the cage. The strips are locked in the femoral cage by a PEEK screw placed between the strips so that each of them is squeezed against the cage (Figs 5 and 6). The tibial cage is inserted with a cannulated screwdriver. Then, we tension the graft using a strong clamp in a rotating manner. We take the knee through its full range of motion, making sure there is no restriction to terminal extension and flexion. Finally, we lock the tibial side with the PEEK screw in 30 of flexion and maximal external rotation. The strips are cut against the cortex. We inspect the graft with the arthroscope, making sure there is no impingement in extension. Bone debris is aspirated with the shaver. The incisions are closed with absorbable sutures on the fascia and the subcutaneous planes. The skin is closed with nonabsorbable sutures. No braces are used in the postoperative period. Table 1 describes TABLE 1. Key Points to Remember During ACL Reconstruction With CFO System 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. Remember that the semitendinosus is distal to the gracilis. Note that 2 loops (4 strands) should be placed around the strips. Be aware that the minimal graft diameter is 8 mm. Mark the graft at 1.5 cm of each extremity with a sterile pen. Keep in mind that the largest part of the graft should be the tibial part. Remember that adequate tapping of the tunnels is crucial. Control graft position with the pen landmarks before locking femoral fixation. Cycle the graft 20 times. Make sure to have complete extension before tibial fixation.

5 GRAFT FIXATION IN ACL RECONSTRUCTION e51 TABLE 2. Main Advantages of Technique Only 1 tendon is harvested. The strength of fixation allows immediate rehabilitation. The tunnel depth available for the graft is 1.5 cm. 360 Bone contact is obtained around the graft. No brace is required. Both cages and strips are magnetic resonance imaging compatible. PEEK is not absorbable (inert). The technique is compatible with double-bundle reconstruction. TABLE 3. Main Limitations and Drawbacks of Technique The size of the graft in small female patients may be insufficient. Instrumentation is not adapted if the graft diameter is less than 8 mm. More bone loss occurs on the femoral side. PEEK is not absorbable (which may complicate revision surgery). A small femoral incision is needed. key points to remember during the use of the CFO system, and Video 1 provides additional details. DISCUSSION The CFO system for ACL 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. The CFO system includes all the instrumentation necessary to perform this technique. Using only 1 hamstring tendon certainly is appealing 3 ; however, the size of the graft may be insufficient in small female patients. A graft with a diameter of less than 8 mm is not compatible with the CFO system. For certain patients, it might also be necessary to harvest the gracilis tendon to obtain a graft of sufficient size. 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. Another downside of this technique is the increased femoral bone loss when compared with an EndoButton technique (Smith & Nephew Endoscopy, Andover, MA). It also requires an additional incision on the superolateral aspect of the knee. This is mandatory for proper cage insertion. The main advantage of the technique is the reliability of its fixation (Table 2). The dilatator compacts the trabecular bone on each side of the tunnel, creating a solid anchor for the cages. 10 The length of the tunnels is maximized by use of an outside-in technique. 11 Furthermore, the absence of interference screws next to the graft creates a 360 bone contact at 1.5 cm in both tunnels, which should allow better graft integration. This fixation technique reduces bungee and windshield-wiper effects of the graft because the point of fixation is located at 1.5 cm of the articulation inside the tunnels instead of being close to the external cortex, as in the EndoButton technique. This might reduce widening of the tunnels in the first postoperative months. 12 No synthetic material is in contact with the articulation because the sutures used to tie the graft are absorbable. This fixation method is also suitable for double-bundle reconstruction. The cages are magnetic resonance imaging compatible and do not produce any artifact (Fig 7). The nonabsorbable PEEK cages are inert and do not create an inflammatory response. However, if revision surgery becomes necessary, they might interfere with tunnel positioning (Table 3). In such cases the cages can be drilled or cut to allow reorientation of the tunnels. The CFO system is a novel technique of fixation for ACL reconstruction that provides a solid anchoring of the graft in the early postoperative period by use of a single hamstring tendon. REFERENCES 1. Pinczewski LA, Lyman J, Salmon LJ, Russell VJ, Roe J, Linklater J. A 10-year comparison of anterior cruciate ligament reconstructions with hamstring tendon and patellar ten-

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