The Central Quadriceps Free Tendon for Anterior Cruciate Ligament Reconstruction

Abstract

The central quadriceps tendon has been used for ACL reconstruction for over 30 years and is proven to yield comparable stability results to hamstrings and BTB autograft reconstructions of the ACL. For 20 years, the quadriceps tendon has been used without bone for ACL reconstruction, with reduced pain and morbidity when compared to BTB and hamstring autograft alternatives. Patients also reach rehabilitation landmarks sooner, presumably because of the reduced post-operative pain after central quadriceps free tendon ACL reconstruction when compared to other autografts. Free tendon fixation techniques have evolved to a point that central quadriceps free tendon has become an excellent alternative for ACL reconstruction.

Keywords

ACL reconstruction, central quadriceps free tendon

Introduction

The central quadriceps tendon has been used for anterior cruciate ligament reconstruction (ACLR) for more than 30 years. However, it remains an infrequently used graft option for anterior cruciate ligament (ACL) reconstruction, despite favorable clinical results in the literature with low donor site morbidity. It is a versatile graft that can be harvested with bone, or as a soft tissue graft alone. The central quadriceps tendon can be used for anatomic, double-bundle, or transtibial reconstructions, as well as for skeletally immature patients. We feel it is an excellent, if not superior, graft option for several other reasons. Compared with the bone–patellar tendon–bone graft, it has 20% more collagen per cross-sectional area, an ultimate load that is 27% greater, and a modulus significantly closer to the native ACL. Additionally, the ultimate load of the remaining quadriceps tendon following harvest is still 21% greater than the intact preharvest patellar tendon. Its major advantages over the hamstring tendon grafts are the ability to accurately predict graft size prior to surgery, larger graft diameter, shorter rehabilitation time, and less pain, as well as no permanent postoperative weakness.

The following harvest technique is minimally invasive, allowing the surgeon to take only the amount of tendon that is needed for the reconstruction while leaving as much undisturbed normal anatomy as possible. Additionally, the fixation technique is simple and allows circumferential graft tunnel healing. This harvest and fixation technique has been used in over 300 ACL reconstructions with excellent short-term results.

Keywords

ACL reconstruction, central quadriceps free tendon

Introduction

The central quadriceps tendon has been used for anterior cruciate ligament reconstruction (ACLR) for more than 30 years. However, it remains an infrequently used graft option for anterior cruciate ligament (ACL) reconstruction, despite favorable clinical results in the literature with low donor site morbidity. It is a versatile graft that can be harvested with bone, or as a soft tissue graft alone. The central quadriceps tendon can be used for anatomic, double-bundle, or transtibial reconstructions, as well as for skeletally immature patients. We feel it is an excellent, if not superior, graft option for several other reasons. Compared with the bone–patellar tendon–bone graft, it has 20% more collagen per cross-sectional area, an ultimate load that is 27% greater, and a modulus significantly closer to the native ACL. Additionally, the ultimate load of the remaining quadriceps tendon following harvest is still 21% greater than the intact preharvest patellar tendon. Its major advantages over the hamstring tendon grafts are the ability to accurately predict graft size prior to surgery, larger graft diameter, shorter rehabilitation time, and less pain, as well as no permanent postoperative weakness.

The following harvest technique is minimally invasive, allowing the surgeon to take only the amount of tendon that is needed for the reconstruction while leaving as much undisturbed normal anatomy as possible. Additionally, the fixation technique is simple and allows circumferential graft tunnel healing. This harvest and fixation technique has been used in over 300 ACL reconstructions with excellent short-term results.

Preoperative Planning

The thickness of the quadriceps tendon can be reliably predicted using the preoperative magnetic resonance imaging (MRI). We routinely measure the thickness of the tendon at the midsagittal patella, 3 cm proximal to the proximal pole ( Fig. 22.1 ). We prefer a partial-thickness harvest when possible based on tendon thickness, although full-thickness grafts can be intentionally taken for patients with thinner tendons (<6 mm).

Surgical Technique

Graft Harvest

With the patient in the supine position, the well leg is placed in a lithotomy positioner. A tourniquet is placed on the operative thigh and then secured in a leg holder. The end of the bed is dropped so that the surgical leg hangs at 90 degrees of flexion. Graft harvest is usually performed under tourniquet at the beginning of the procedure.

With the leg flexed to 90 degrees, the proximal pole, medial, and lateral borders of the patella are marked. It is very important to distinguish the lateral border of the patella from the lateral trochlear ridge and is often helpful to extend and flex the knee to confirm these landmarks. A 1.5–2 cm vertical mark is made extending proximally from the proximal pole of the patella, just lateral to the midpoint ( Fig. 22.2 ). The tissue beneath the incision is injected with 6 cc of local anesthetic to separate the subcutaneous fat from the quadriceps retinaculum. A longitudinal incision is made with a 15-blade, and the subcutaneous fat is excised. It is very important to widely remove this underlying subcutaneous tissue in order to adequately visualize the quadriceps tendon. This is especially important when using a 1–2 cm incision. A Ray-Tec sponge is then introduced into the wound and pushed in proximally to bluntly dissect the tissue off the anterior quadriceps tendon and anterior patella ( Fig. 22.3 ). A large key elevator is then used to scrape the remaining tissue off the proximal 7-cm quadriceps tendon. An Army-Navy retractor is placed into the proximal apex of the incision, and the arthroscope is inserted with the fluid turned off. With the camera looking down (posterior) at the tendon, the border of the vastus medialis, distal apex of rectus femoris tendon, and the border of the vastus lateralis are identified. Care is also taken to identify and coagulate any vascular branches that may be damaged during graft harvest. The arthroscope is then moved proximally until the distal end of the rectus femoris muscle is seen ( Fig. 22.4 ). The camera is turned to face upward (anteriorly), and a mark is placed on the anterior thigh at the point of maximum transillumination ( Fig. 22.5 ). This point identifies both the direction of graft harvest and the most proximal point of tendon harvest to avoid damage to the rectus femoris muscle.

The Quadriceps Harvest Knife (Athrex, Naples, Florida) is used for graft harvest. It is a double-bladed scalpel that controls for both width and depth of the cut. It has a standard depth stop at 7 mm, which is less than the thickness of most quadriceps tendons and thus prevents incising the joint capsule. It comes in 9-, 10-, and, 11-mm widths, so the desired size of graft can be taken. After selection of the correct size blade, the Harvest Knife is introduced into the wound. It is often helpful to use a retractor to elevate both the skin and subcutaneous fat layer so the knife can be moved proximally. The Harvest Knife is introduced to the previously marked point, and its length is measured via markings on the handle and the proximal tip of the patella ( Fig. 22.6 ). We identify the 7-cm length and push the Harvest Knife into the tendon; then we pull back until the blades hit the proximal pole of the patella. A 15-blade knife is then used to connect the two limbs of the incision while removing the tendon from the superior pole of the patella ( Fig. 22.7 ). Pick-ups are used to lift the distal limb of the graft, and the 15-blade scalpel is used to sharply dissect the distal portion of the graft. This is the part of the harvest that will determine the graft thickness. The depth of the vertical limbs can be used as a reference for graft thickness when harvesting the partial-thickness graft. A thin fat layer exists deep to the tendon and superficial to capsule, which should, if encountered, alert the surgeon to avoid deeper dissection or risk capsular violation ( Fig. 22.8 ). Once the distal 2 cm of graft is released from the tendon, an Allys clamp is applied to the end of the graft. With longitudinal tension applied to the end of the graft, Metzenbaum scissors are used to release the graft proximally. Once 3–4 cm of graft has been elevated, a FiberLoop suture is used to whipstitch the tendon (four throws), starting 1.5–2 cm proximal to the tendon end ( Fig. 22.9 ). It is important to lock the last throw, allowing the needle to exit the central aspect of the graft ( Fig. 22.10 ). The needle on the end of the fiber loop is not removed. With traction on the sutures, Metzenbaum scissors can be used to dissect the graft proximally. We like to release the graft 5–6 cm proximal. With firm tension on the sutures, the Quadriceps Tendon Stripper/Cutter (Arthrex, Naples, Florida) is used to strip and then cut the graft proximally once the desired graft length is achieved. It is important to hold the Stripper/Cutter sideways to allow visualization of the measurement markings and prevent the device handle from contacting the patient’s thigh ( Fig. 22.11 ). We prefer graft lengths of 7 cm. This will usually avoid damaging the rectus femoris muscle and allow 3 cm of graft intra-articularly as well as 2 cm of tendon in each bone tunnel.