History

The concept of using the quadriceps tendon as a graft in anterior cruciate ligament (ACL) reconstruction was first introduced by Marshall in the 1970s. His concept was much different from today’s full quadriceps graft and involved using the quadriceps tendon (QT) combined with the fascia over the patella coupled with a strip of patellar tendon (PT). His technique was abandoned after biomechanical testing showed it to be much weaker than the native ACL and other studies showed poor clinical results.

In the mid-1980s, Blauth and Yasuda et al. reported results using a central QT graft with a bone plug. Their results were inferior compared with the use of bone-patellar tendon-bone (BTB), and the QT was largely ignored as a graft source for ACL reconstruction.

Interest began to be revived in the late 1990s and early 2000s after reports of results comparable to BTB and hamstrings by Staubli and Fulkuson, and later by Shelton and Holt, Kim et al., and Han et al. using a bone/QT graft. Theut et al. first described harvesting the quadriceps graft without a bone plug in 2003, eliminating the potential completion of patella fracture.

Clinical results from these authors demonstrated stability, range of motion, and functional outcomes to be equal to BTB grafts. The biggest advantage was less surgical morbidity with QT compared with BTB, especially in eliminating anterior kneeling pain and numbness.

Over the past 10 years the QT graft has slowly increased in popularity. In 2010 a review of graft choices found about 2.5% of ACL reconstruction utilized a QT autograft. In 2014 Middleton collected data at an international symposium on ACL surgery and found 11% of the ACL surgeries done by the 35 ACL surgeons in attendance used QT. The fact that stability, motion, and functional results compare favorably with BTB and hamstrings, and that surgical morbidity is decreased, has positioned the QT as a third autograft option in ACL reconstruction.

Anatomy

The QT is formed at the confluence of the four parts of the quadriceps muscle: the rectus femoris, vastus intermedius, vastus medialis, and vastus lateralis. The larger rectus femoris and smaller vastus intermedius give origin to the part of the tendon from where the QT graft is harvested. They are separated by a small layer of fat to within 6 cm of the patella, after which the tendon is solid. The average width of the QT is 27 mm with an average thickness of 8 mm. The average length of the QT measured from the superior patella is 74 mm in females and 81 mm in males. The proximal pole of the patella slopes down at about a 45-degree angle from distal to proximal, and careful dissection of the tendon from the bone can add approximately 10 mm to the length of the graft. If a bone plug is used, another 20–30 mm of length can be added to the graft.

In our experience, the thickest part of the QT is medial, and the graft harvest should cheat toward the medial side of the tendon next to the vastus medialis obliquus. In average-size adults, a 7–8 mm thick, 10 mm wide, and 85–95 mm long graft can be harvested without violating the suprapatellar pouch. If the knee joint is inadvertently entered, then meticulous closure of the defect should be done after the graft is harvested.

Once the graft is obtained, the defect in the tendon is closed and the graft prepared. The proximal end is split between the layer of fat and a whipstitch placed in each limb. If suspensory fixation is used, the graft split is continued toward the patella end of the graft to within 10 mm of the end so the suspensory fixation device can be attached. The graft orientation will be the distal patella end for the femoral side and the proximal split end for the tibial side. The proximal pole of the patella slopes downward from distal to proximal, in this manner, a 10 mm wide by 7–8 mm thick by 85–95 mm long graft can routinely be obtained.

Histology

Hadjicostas et al. compared QT with PT by light and electron microscopy. He found 20% more collagen per volume in the QT compared with the PT. The QT also had a higher fibroblast density than the PT.

Lee et al. demonstrated a bimodal pattern of large and small diameter fibrils in mature QT grafts at biopsy. This is similar to the native ACL. Large fibrils are necessary for strength, and similar biopsies of mature PT grafts have shown a loss of the large fibrils and a unimodal pattern of mainly small diameter fibrils.

Biomechanics

The QT graft is approximately 1.8 times as thick as the PT graft, which allows more collagen and thus more strength. Harris et al., Staubli et al., and Slone et al. all found the QT graft to be significantly stronger than a similar width PT. Both the QT and the PT grafts were stronger and stiffer than the native ACL.

Results

Recent evidence has shown that ACL reconstruction using QT autograft compares favorably with both BTB and hamstring grafts. Multiple studies show no statistical difference in arthrometer, Lachman, or pivot shift testing.

Likewise, function testing with Lysholm and Tegner scores has found no differences among the three autografts. International Knee Documentation Committee scores also show no statistical difference.

Recovery of quadriceps strength is similar to BTB. Cybex testing at 1–2 years postoperatively shows recovery of the quadriceps muscle of 85%–90% of the normal side.

QT grafts show an advantage over BTB grafts in reducing surgical morbidity. Anterior kneeling knee pain is reduced to 4%, compared with over 27% with BTB. Likewise anterior knee numbness is reduced from 53% with BTB to 1% with QT. Better extension and flexion are seen compared with BTB.

Higher failure rates seen in young females with hamstring grafts have not been seen with QT. Since the hamstrings are not violated with QT, recovery of its strength is not an issue.