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ligament substitute used was the LARS (Ligament Advanced Reinforcement System).
Made of polyethylene terephthalate, this
material also promotes biologic tissue ingrowth in the intra-articular part. Early results have been comparable to or
better than patellar tendon grafts54, but long term studies are awaited.

Although
debate persists over the optimal graft choice for ACL reconstruction, the use
of hamstring autograft has seen an increase in popularity over recent years. Historically,
central-third BPTB autograft was favoured.with its proven track record and bone
to bone tunnel healing. However, BPTB harvest is known to be associated with
significant morbidities, including chronic anterior knee pain, quadriceps
weakness, patellar fracture, and patellar ligament disruption. Advocates of
hamstring autograft believe it provides a less invasive approach without
disturbance of the extensor mechanism, limiting the potential for catastrophic complications.
In addition, Hamner et al.1 showed that combined 4-strand hamstring grafts were stronger and
stiffer with greater load to failure than historical results with BPTB
autograft. In a similar study by Wilson et al.,2 superior load-to-failure results were confirmed with 4-strand
hamstring autograft (2,422 N) compared with matched BPTB autograft (1,784 N).(main)
Cadaveric analysis has shown a linear correlation between maximum load to
failure and graft crosssectional area.1 These laboratory data have been confirmed clinically, with
Magnussen et al.6 reporting increased revision rates for smaller-diameter grafts. By
use of simple anthropomorphic measurements and standard imaging, efforts have
been made to predict  semitendinosus and
gracilis graft diameter to identify patients at risk of undersized
grafts.(main)

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Recent
literature in anterior cruciate ligament reconstruction (ACLR) using hamstring
autograft suggests that smaller graft sizes may be correlated with an increased
rate of graft failure 8, 10.

 

Leiter et al.21  found
rerupture rates of reconstructed ligament was 9% with hamstring graft. A study
by Leys et al. in 51 patient of hamstring graft with 15 years of follow up,
resurgery rate was 17%. A study by Streichet al.6 on 40 patients
with four strand hamstring graft with 10 year follow up showed rates of
resurgery was 8%.

Some
studies demonstrated that the strength of a graft tendon was related to size 15 and that the smaller the size of the
tendon, the greater the likelihood of a weaker and more unstable graft tendon 21park

A study was done by Patel et
al.7  on twenty-five patients
who underwent arthroscopic anterior cruciate ligament reconstructions using
autogenous quadrupled hamstring graft (semitendinosus (ST) and gracilis). All
patients underwent standard surgical procedure and rehabilitation protocol.
These Patients were assessed using IKDC and Lysholm knee scoring scale after
six-month: In all patients at 6
months post-surgery the mean Lysholm knee score was 91.2 (range, 63 to 99)and
the mean IKDC score was 90.7 (range, 60 to 98). They found that all patients
were able to perform single leg hop test and had full range of motion at 6
month follow up.

Williams
et al.8 done a study on one hundred and twenty-two consecutive
patients who had an isolated, symptomatic anterior tibial subluxation
associated with rupture of the anterior cruciate ligament and  treated with reconstruction of the anterior
cruciate ligament with a four-strand autologous semitendinosus-gracilis (STG)
tendon graft.
Reconstruction of the anterior cruciate ligament with use of a
four-strand hamstring tendon auto graft eliminated anterior tibial
subluxation in 89% of patients who were examined at a minimum of two years
postoperatively. The overall rate of failure was 11%.

A
study done by Witvrouwet al.9 on 17 patients with central third bone
patella tendon bone auto graft reconstruction and compared with 32 patients of
double semitendinosus or double gracilis auto graft reconstruction. In this
study, they found the laxity of the hamstring tendon graft was inferior to the
patellar tendon graft.

A
potential disadvantage of hamstring autograft for ACL reconstruction is the
inherent variability in graft diameter. Biomechanical testing has shown a
correlation between graft cross-sectional area and maximum load to failure.
Historically, authors have recommended the use of grafts at least 7 mm in
diameter, although limited evidence supports this recommendation. 10,11

Magnussen
et al.6 recently
evaluated hamstring autograft diameter as a predictor for graft failure and the
need for revision. In a study of 256 patients with hamstring autograft ACL
reconstruction, 7.0% required revision at a mean of 14 months follow-up.
Decreased graft diameter and age were shown to be associated with increased
revision rates. Grafts greater than 8 mm in diameter had a revision rate of
1.7%, 7.5- to 8-mm grafts had a revision rate of 6.5%, and grafts of 7 mm or less
had a revision rate of 13.6%. When grafts of 8 mm or less were used in patients
aged younger than 20 years, the revision rate rose to 16.5%. Because of concern
for a potentially undersized hamstring autograft, numerous studies have sought methods
to predict graft dimensions preoperatively. In a prospective evaluation, Treme
et al.7 indicated that patients with
a weight less than 50 kg, height less than 140 cm, body mass index less than
18, and leg circumference less than 37 cm are at highest risk of a hamstring autograft
diameter of less than 7 mm. In addition to anthropomorphic data, preoperative
imaging has been used to estimate tendon size. Bickel et al.5 used axial magnetic
resonance images to determine the probability of obtaining a graft considered
to be of sufficient size in an adolescent population.(main)

 

A
study by Lavery et al.13 showed that Hamstring autografts for ACL reconstruction
have an inherent variability in graft diameter. By use of an EndoButton for
femoral tunnel fixation, a quadrupled hamstring graft may be
converted into a 5-strand graft by creating 3 equal strands of the larger
semitendinosus combined with a double strand gracilis.

Lee et al.14 described
a technique for obtaining a large diameter ACL graft construct from autologous
hamstring graft without allograft supplementation. They made five strand by
folding of three layers of semitendinosus and two strands of gracilis and they
noted that graft diameter increase by 1 to 1.5 mm.

A study by Prodromos et al.15  showed that five strand hamstring graft
has higher stability than 4 strand hamstring graft. They believed that 5 strand
hamstring graft is preferable over 4 strand hamstring for ACL reconstruction. They operated 
20 patient by using five strand hamstring graft(using three strand
semitendinosus and two strand gracilis). Results were compared with a
previously reported cohort of 133 knee reconstructed by the same surgeon using
four strand hamstring graft (two strand semitendinosus and two strand
gracilis). They evaluated them at 24-104 months postoperatively and  found  that
5 strand hamstring graft is more stable than four  strand hamstring graft.

A study by Tashiro et al.16
shows significant decrease in isometric and isokinetic hamstring strength in ST
and STG groups which was studied at 70 degrees or more flexion.
hamstring tendon graft is multistranded and has a larger surface area, it could
be advantageous in promoting revascularization. In fact, recent clinical
studies have proved the superiority of the hamstring tendon method over the
patellar tendon procedure. Patients treated with hamstring tendon grafts are
less likely to have patellofemoral pain26 and extension loss6,26 and more
likely to have better recovery of quadriceps muscle strength.3 Another advantage
of the hamstring tendon graft technique is preservation of hamstring muscle
strength. In spite of tendon harvest, most of the reported series have shown almost
full recovery of knee flexor strength after surgery.1, 2, 9, 10, 12, 15, 25,
27,29

A study by Nakamura et al.17 shows
that removing semitendinosus and gracillis tendon result in a significantly
lower mean maximum standing knee flexion angle compared with harvesting
semitendinosus alone in post ACL reconstruction patients.
Seventy four consecutive patients who had undergone ST (n:49) or STG (n:25) ACL
reconstruction underwent is kinetic muscle strength testing at 2 years
post-surgery. Measurements of the maximum standing active knee flexion angle
with the hip extended were also taken. Each patient stood on the uninvolved
leg, with the ipsilateral hip joint extended against the wall. The ankle joint
of the involved side was kept in full plantar flexion to exclude additional
knee flexion by the contraction of the iliopsoas and the gastronemius muscles.
Isokinetic testing showed that, in both the ST and STG groups, the knee flexor
strength of the involved leg was less effectively restored at 90 degrees of
knee flexion than at the angle at which the peak torque was
generated.Conversely, no significant difference was seen in the side-to-side
ratio in either the peak flexion torque or the 90 degrees flexion torque
between the groups. The side-to-side ratio in mean maximum standing knee flexion angle was significantly lower in the
STG group than in the ST group. This study suggested that the loss of knee
flexor strength following the harvest of the hamstring tendons may be more
significant than had been estimated earlier.

Lipscomb et al.18  after a retrospective analysis of 482
cases, found no significant loss of knee flexion strength at an average of 26
months after ST or STG harvest. In
the reconstructed knee in which both semitendinosus and gracilis were used,
hamstring strength was found to average 99% compared to the normal knee. When
the semitendinosus alone was used there was no difference (102%) from the
normal knee.

A study by Soon et al.19 for
early prospective changes on seventy six patients who was assessed
preoperatively, at 3 and 6 months post operatively the hamstring and quadriceps
strength was assessed by using biodex machine, KT 1000 and IKDC score. They
found that strength of hamstring and quadriceps improved by 6 month
post-operative period. The recovery by quadriceps is more marked and for laxity
the side to side difference at 30 pounds was 2.75 mm after 6 months. Overall
side to side difference was less than 5 in 66 patient (acceptable level is less
than 5 for graft success), in IKDC scoring 71 patients have normal or near
normal knee at 6  month post-operative by
subjective assessment. Not a single patient had knee pain at rest. Sensory
deficit was present in 3 patients.

A study by Spicer et al.20
shows that in 50% patients area of sensory changes present in front of the knee
and of these 86% patients shows sensory changes in distribution of infra
genicular branch of saphenous nerve.