الفهرس 
Biology of hamstring graft integration and regenerationOnly 14 pages are availabe for public view
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Abstract
The anterior cruciate ligament (ACL) injury is the most common
ligament injury in the knee. Greater participation in sporting activities by
the general population continues to expose more individuals to the risk
of an ACL tear. (1) ACL is a complex structure whose orientation, construct,
and biology are directly related to its function. It has also an important
function in carrying loads throughout the entire knee motion and so it
plays an important role in knee stability and proprioception. (2)
Injuries to this vital ligament are reported to represent about 1/3 of
sports injuries to the knee joint, although injuries can also occur in non-
sportive individuals. Many authors have found football, basketball, and
skiing to be the most common activities during which a rupture of the
ACL has occurred in young patients. (3) Reconstruction of the torn ACL is a
common surgical procedure for orthopedic surgeons, especially those
who are interested in sports medicine. Although some patients who are
not involved in sports can function without complaint with an ACL-
deficient knee, most patients experience pain and recurrent episodes of
instability. (4)
Operative treatment is usually recommended for younger patients
who wish to return to competitive activities. The goal of any ACL
reconstruction is to restore normal knee stability to approximate normal
knee kinematics. The fact that so many different methods have been
described for the reconstruction of ACL in patients with chronic
functional instability indicates that the ideal solution to this problem has
not yet been found. (5)
Introduction
11
ACL reconstruction with autogenous Gracilis and Semitendinosus
(G/ST) tendons has become a common surgical procedure. The
advantages of using them are well known, the most important is their
relatively low donor site morbidity. (6) The tendons can be harvested
through a smaller incision than that used for harvesting bone-patellar
tendon-bone (B-PT-B), which may help to minimize postoperative pain.
In patients with extensor mechanism problems or those who engage in
sports with a high incidence of patellar tendonitis, the hamstrings graft
should be considered. (7) This latter graft has an ultimate tensile load
reported to be as high as 4108 N, which is considered twice the strength
of the native ACL. (8)
The autograft arthroscopic single-bundle (SB) is the “gold standard”
technique for ACL reconstruction. (9) The femoral tunnel placement can be
created through either anteromedial (AM) or transtibial (TT) techniques.
It has been postulated that the single-bundle transtibial ACL
reconstruction places the graft in a non-anatomical femoral insertion site.
Given that the most common cause of ACL reconstruction failure has
been the non-anatomical femoral tunnel placement, the use of the
anteromedial portal (AMP) for drilling the femoral tunnel in the (SB)
technique was suggested as a method to place the graft in an anatomical
position and improve rotational stability without increased complexity.
(10)
Graft fixation is an important factor in ACL reconstruction,
especially in the first two months of healing. Therefore, the fixation must
be strong enough to resist in vivo forces during this period. There are
different methods of graft fixation on the femoral side. They can be
Introduction
12
classified into Cortical suspensory fixation (e.g. Endobutton – Tightrope)
or Cross pins fixation (e.g. Rigidfix – Transfix) or Aperture fixation (e.g.
Interference screw). (11)
Cortical suspensory devices have been widely used in ACL
reconstruction for femoral side graft fixation. Various studies have shown
that cortical suspensory devices have the necessary biomechanical
properties concerning ultimate failure strength, displacement, and
stiffness for the initial fixation of soft tissue in the femoral tunnel for ACL
reconstruction. (12)
Cortical suspensory devices are available in two varieties, Fixed
Loop device FLD (Endobutton) and Adjustable Loop device ALD
(Tightrope). Endobutton is the first-generation suspensory fixation with
a fixed-length loop. The length of the loop is fixed but it is stiffer and
slippage-free which seems to have created a more favorable
biomechanical environment. (13)
Tightrope is the second-generation suspensory fixation device with
an adjustable-length loop which is reduced after flipping by tightening
the rope. It allows full-length filling of the graft part of the femoral tunnel
and some degree of final tightening to tension the graft even after
placement of the graft. This seems to be the theoretical advantage of
Tightrope over Endobutton which removes the final slack off the knee
after the placement of the graft and prevents long-term laxity of the
reconstructed ACL. (13)