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techniques, particularly high-dose gamma
irradiation have been shown to decrease graft
strength [13].
AUTOGRAFT CHOICE
The question of whether hamstring or patellar
tendon autograft yields better outcomes
following ACL reconstruction is one of the
most researched and contested questions in
orthopaedic sports medicine. Numerous
systematic review articles have yielded
conflicting findings over the years regarding
which graft is best, but most demonstrate no
clear difference in outcomes [6]. A detailed
review at the data reveals several differences
between the grafts, some of which has been
further confirmed by large cohorts and
registries.
The most common question is whether a
difference in failure risk exists between these
grafts. A systematic review of eight prospective
studies with minimum 5-year follow-up from
2011 demonstrated a trend toward increased
failure risk with hamstring grafts (odds ratio
1.59, 95% confidence interval: 0.79 - 3.22) that
did not reach statistical significance [6]. A
recent systematic review limited to only high
quality randomized controlled trials (6 studies)
demonstrated an increased failure risk in the
hamstring group (15.8%) relative to the
patellar tendon group (7.2%) (
p
=0.02) [15].
Several large registries have recently published
data regarding differences in failure risk
between hamstring and patellar tendon
autografts. The Scandinavian ACL registries,
together reporting on 45,998 primary ACL
reconstructions, noted the risk of revision
surgery in the hamstring autograft group was
1.59 (95% CI, 1.35-1.89) times that of the
patellar tendon group [3]. They noted elevated
risk with hamstring graft across all age groups,
but noted the effect to be greater in patients
participating in cutting and pivoting sports.
The MOON group in the US noted a similar
odds ratio for graft failure with a hamstring
autograft versus patellar tendon autograft
(1.60; 95% CI, 0.89-2.90) in 2683 knees, but
the finding did not reach statistical significance
(
p
=0.12) [5]. The Kaiser database in California
noted that patients under age 21 had a 1.61
times (95% CI, 1.20-2.17) higher risk of graft
failure when treated with a hamstring autograft
compared to the patellar tendon autograft [9].
Interestingly, they noted no such difference in
older patients.
Numerous factors do and should play a role in
graft selection beyond absolute failure risk.
Knee laxity as measured with the Lachman and
especially pivot-shift may be less in patients
reconstructed with patellar tendon grafts [6,
17]. The clinical relevance of these findings is
not completely clear as these data have not
been demonstrated to translate into improved
patient-reported outcome score. Systematic
review data are clear that patients who undergo
reconstruction with patellar tendon grafts are at
increased risk of anterior knee pain and
kneeling pain a 5-year minimum follow-up
compared to those treated with hamstring
autograft [6, 17]. While data are less consistent,
patients reconstructed with patellar tendon
autograft may also have increased risk of
development of osteoarthritis than those treated
with hamstring grafts [6, 18].
Quadriceps tendon grafts have been gaining in
popularity in recent years as many feel they
are able to provide results similar to those
obtained with patellar tendon autografts
without the associated morbidity of a patellar
tendon graft harvest. A recent review by Stone
et al.
that included 1154 quadriceps autograft
ACL reconstructions demonstrated the safety
of the graft and preliminarily confirmed the
comparable results and decreased morbidity of
this graft choice relative to patellar tendon
grafts [16]. Larger studies and more experience
with this graft are needed for a definitive
assessment of failure risk and potential
morbidity of this graft choice.