*Red numbers
indicate references

INTRODUCTION
Significant advances in surgical reconstruction of the anterior
cruciate ligament (ACL) have been made since Jones’ described
open reconstruction with the central one-third patellar tendon
in 1963.29 Advancements in technology, arthroscopic instrumentation,
and surgical skills have decreased surgical morbidity while improving
functional outcome.5,
23
Continued technological
and surgical improvements in the 1990’s eventually enabled surgeons
to perform ACL reconstructions endoscopically. SIZE=”-2″>3, 4, 19, 23, 24, 37

During the evolution of ACL reconstruction surgery, numerous
graft sources have been described. Currently, the most commonly
utilized tissues for ACL reconstruction are autologous semitendinous/gracilis
tendons (ST-G), central one-third patellar tendon (B-PT-B), and
allograft patellar tendon. >13, 14, 21, 22, 31, 32, 46, 49, 50
Each of these grafts has been touted
to reliably restore knee stability, thereby enabling many patients
to return to pre-injury activity levels. Despite these reports,
complications have been noted with all three types of tendons,
the most frequent being anterior knee pain. SIZE=”-2″>1, 6, 7, 9, 10, 12, 17, 18

Based upon its proven efficacy,
the central 1/3 autologous patellar tendon is considered by a
large number of orthopaedic surgeons to be the graft of choice
in the symptomatic ACL-deficient patient. However, the incidence
of anterior knee pain with the use of this graft has been reported
from 13% to 47%, which diminishes the functional outcome in a
large percentage of individuals. SIZE=”-2″>1, 35, 43-45, 51 Moreover, due to technical factors such as tunnel
angle and graft length, many B-PT-B grafts cannot be secured
at the joint level, resulting in non-anatomic graft fixation.
In an effort to eliminate these problems, other graft sources
have been explored. The ideal ACL graft should result in minimal
or no damage to the patient’s tissues after harvest. It should
enable immediate rigid fixation and reproduce the normal anatomy
of the native ACL. It should also restore normal proprioception
and kinematics to the knee. Although numerous graft sources have
been reported, currently, no graft material, autograft or allograft,
can meet all these requirements.

In an effort to minimize post-surgical
anterior knee pain after ACL reconstruction, the use of semitendinosus/gracilis
tendons has been reported. Advocates of ST-G (hamstrings) point
out that post-operative patellar pain is diminished by virtue
of the patellar mechanism not being violated during graft harvest.
Various authors have reported the incidence of anterior pain
to vary from 3% to 21% following hamstrings ACL reconstruction.<FONT
COLOR=”#ff0000″ SIZE=”-2″>2, 11, 15, 26, 30,
33, 42 However, in the
author’s experience, the use of hamstrings for ACL reconstruction
does not eliminate anterior knee pain in many patients. In addition,
some authors have reported increased tibial translation in females
after ST-G ACL reconstruction. >16

Allograft B-PT-B has been advocated
as an alternative graft source due to the lack of harvest morbidity
and decreased operative time required. SIZE=”-2″>25, 32, 36, 41, 46 However, despite the diminished risk of disease
transmission, opponents of allografts cite reports of prolonged
graft-tunnel healing and intraarticular reactions to some allografts.<FONT
COLOR=”#ff0000″ SIZE=”-2″>28, 40

As a result of the continued
controversy regarding the correct ACL graft source, an alternative
graft has emerged, the central quadriceps tendon (CQT). The central
quadriceps tendon was reported as a graft source as early as
1979 by Marshall et al, however, it did not gain popularity among
surgeons until the 1980’s and 1990’s. SIZE=”-2″> 8, 21, 34, 47 Proponents of the CQT cite it’s greater cross-sectional
area, lower strain at failure, and lower modulus of elasticity
when compared to patellar tendon. SIZE=”-2″>48
Advocates have also cited the lower incidence of patellofemoral
symptoms after CQT graft usage. >20, 31
Our experience at the University of South Alabama Medical Center
is similar, with less then 5% of patients demonstrating postoperative
anterior knee pain symptoms after CQT ACL reconstruction.

The CQT consists of a central
portion of the quadriceps tendon approximately 10-11mm wide.
The graft depth extends 7mm with an average length of approximately
80-90mm. When the graft is harvested as the initial portion of
the surgical procedure, the central portion is obtained without
violation of the suprapatellar pouch or transection of the quadriceps
tendon. This eliminates the need to repair the pouch or tendon
before proceeding with the arthroscopic portion of the procedure.

Initial descriptions of the use of the CQT described harvest
of the tendon without a bone block from the patella.31 Prior
to the development of bioabsorable screws for soft tissue fixation,
such a graft would have required the tendon ends had to be secured
by sutures tied over a post, such a staple, button, or screw.
Several biomechanical studies have demonstrated that such fixation
does not reconstitute the normal isometricity of the ACL, with
increased instability noted as the tibial side is fixed further
away from the articular surface. SIZE=”-2″>27, 38
Consequently, many authors now advocate graft fixation near the
articular surface insertions of the native ACL. SIZE=”-2″>39
When the CQT is being contemplated as a graft source, articular
fixation can be accomplished by harvesting a patellar bone block
and fixing both ends of the graft with bioabsorbable screws near
the surface of the tibia and femur.

SURGICAL TECHNIQUE
After previous studies (radiographs, MRI) and clinical examination
confirm that the ACL is disrupted and causing symptomatic instability,
the patient is brought to the operating room for reconstruction.
The CQT is harvested through a short 2-3 inch incision obliquely
along the lines of the quadriceps mechanism. After delineation
of the quadriceps tendon, a 10mm x 7mm x 85mm graft is harvested,
being careful to not violate the suprapatellar pouch. At the
distal end of the quadriceps tendon a 10mm x 25mm x 8mm bone
plug is harvested from the proximal end of the patella. The patellar
defect can be later filled with cancelleous bone from the tibial
reamings or with allograft chips. The CQT is sized on a back
table to fit through the smallest tunnel that the tendon (not
the bone) will glide through easily; the bone plug is trimmed
to fit accordingly. This usually represents 9-10mm. Two #2 Ethibond
sutures are placed in the patellar bone plug, while two #1 Ethibond
sutures are whipped stitched in the tendon end.

After the stitches are in place
and CQT has been sized, appropriate markings are made to aid
the surgeon during arthroscopic reconstruction. In our use of
the CQT, we place the tendon side in the femoral tunnel, with
the patellar bone block in the tibia. First, a pen mark is made
at the bone-tendon junction. Next, a distance of 35mm is measured
from the CQT-bone junction. This marked area represents the approximate
intraarticular distance of the native ACL. This distance is approximately
30mm in most individuals, however, we allocate an additional
5mm in case the graft slides more proximally in the femoral tunnel.
The distance of the remaining tendon represents the portion of
the tendon that will be pulled into the femoral tunnel (~25mm).
The following calculation is what we use in preparing the CQT
graft for implantation:
85mm {total graft} – 60mm {bone plug + intraarticular
tendon} = 25mm {femoral tunnel}
The graft is set in a moist sponge until later implantation.

After harvest of the CQT, a
routine knee arthroscopy is performed. We routinely perform a
5-7mm lateral notchplasty, along with debridement or repair of
any meniscal lesions. Using a standard tibial guide set at an
angle of 55o, we drill a 9mm tibial tunnel centered 5mm anterior
to the PCL within the footprint of the native ACL. After the
posterior portion of the tibial tunnel has been debrided of all
soft tissue and rasped posteriorly, a 7mm offset endoscopic guide
is placed through the tibial tunnel at the “10:30”
or “1:30” positions on the posterior femoral notch.
A 9-10mm femoral tunnel is reamed to the depth of the previous
calculations (~ 25mm).

After reaming, an eyed Beath
pin (Arthrex, Naples, FL) is placed in the femoral tunnel. Sequential
impaction dilatation of the tibial and femoral bone tunnels is
performed to increase the bone density of the tunnels for bioabsorable
screw placement. After the tunnels are dilated to the size of
the graft (9-10mm), the tendon side of the CQT is brought into
the femoral tunnel. Through the anteromedial or an accessory
anterior portal, a bioabsorable screw of the same diameter as
the femoral tunnel is placed anterior to the graft. Fixation
of the graft is assessed by pulling upon the tibial sutures,while
the knee is put through a range of motion. Tensioning the graft
through several motion cycles diminishes creep within the graft
prior to tibial fixation. After the graft is assessed in extension
for signs of impingement, the knee is placed in 10o-20o of flexion
with 5kg of tension place upon the tibial sutures. The graft
is fixed adjacent to the tibial articular surface with a 10mm
bioabsorable interference screw. The knee is assessed for anterior
tibial translation and the wounds closed with absorbable sutures.
Prior to waking the patient, an intraarticular pain pump is placed
within the knee.

CLINICAL EXPERIENCE
At the University of South Alabama Medical Center, our experience
with CQT spans over 2 years, with nearly 20 cases. To date we
are gathering 2 year follow-up data. 1 patient ruptured his graft
during athletics (collegiate athlete) at 9 months postoperatively.
No patient has reported significant patellofemoral pain and there
have been no ruptures of the quadriceps tendon. All patients
have been happy with their results, indicating that they believe
the procedure improved their quality of life.

Other authors have reported
good results with the CQT. Fulkerson reported excellent results
with the use of the CQT with either endobutton or bioabsorbable
screw fixation.20,
31
Leitman et al reported
on 65 CQT graft cases with a KT-1000 side to side differences
of 2.1mm at 1-2 year follow-up. The authors noted that no patient
had patellofemoral pain and all subjects had returned to their
previous level of activity with no instances of quadriceps tendon
rupture.31

CONCLUSIONS
Individuals with a disrupted anterior cruciate ligament and symptomatic
knee instability often require surgical reconstruction of the
ACL. Over the last several decades, tremendous technological
advances have enabled surgeons to reconstruct the ACL with a
more anatomic and durable graft, while minimizing postoperative
morbidity. As the evolution of ACL graft material continues,
numerous graft choices are available. The central quadriceps
tendon (CQT) is an alternative graft source with biomechanical
properties comparable to or better than a bone-patellar tendon-bone
or double-looped hamstrings graft. In early follow-up studies,
patients undergoing CQT ACL reconstruction have demonstrated
minimal patellofemoral symptoms and excellent clinical function.
The CQT provides another weapon in the orthopaedic surgeon’s
repertoire of surgical graft alternatives to reconstruct the
symptomatic ACL-deficient knee.

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Address correspondence to:
Albert W. Pearsall, IV, MD
Department of Orthopaedic Surgery
University of South Alabama Medical Center
2451 Fillingim Street
Mobile, Alabama 36617
Email: apearsal@usamail.usouthal.edu