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Volume 8 • Issue 2 • 1000447
J Trauma Treat, an open access journal
ISSN: 2167-1222
Research Article Open Access
Moniz et al., J Trauma Treat 2019, 8:2
Research Article Open Access
Journal of Trauma & Treatment
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ISSN: 2167-1222
Keywords: Morphology; Chi-square analysis; Cadaveric anatomy;
Magnetic resonance imaging
Introduction
Gra size is an important factor in determining a satisfactory
outcome in anterior cruciate ligament reconstruction (ACLR). Optimal
gra size is yet to be accurately dened in the literature although gras
larger than 7 mm have been found to have lower failure rates and an
inverse correlation between ACL gra size and anterior-posterior
tibio-femoral translation [1-3]. Furthermore, gras with larger cross-
sectional area have superior patient reported outcomes [4]. is body
of literature indicates the mechanical and clinical benet of increasing
gra size when performing ACLR.
Gras that are too large, however, may cause gra-notch mismatch
leading to gra impingement, loss of extension (LOE) or failure [3,4].
Literature reports mean gra diameter used of a four-strand hamstring
(HS) gra to between 7.5 ± 0.7 mm for females and 7.9 ± 0.9 mm for
males [5]. Signicant morphological variation exists between hamstring
size across the population therefore a portion of the population may
have insucient hamstring tendon to create a sucient ACL gra
[1,5,6]. Gras may be increased in size by tripling or quadrupling
under harvested hamstrings, adding or selecting large sized allogras or
augmenting the autogra with a prosthetic ligament. Oversized gras,
however, may increase the risk of gra notch mismatch, subsequent
impingement, LOE and the need for primary or delayed notch plasty.
Gra selection and conguration largely determines the
morphological and mechanical features of the reconstructed ACL gra.
Early single stranded hamstring gras have been shown to be inferior
to both the native ACL and the central one third patellar tendon
gra in terms of both maximal tensile load and cross sectional area
[7,8]. To increase hamstring gra size surgeons have doubled, tripled
or quadrupled a single or combination of hamstring tendons. is
technique has been shown to achieve gra dimensions and mechanical
properties superior to the native ACL and other commonly used ACLR
*Corresponding author: Moniz S, Fiona Stanley Hospital, 11 Robsin Warren Dr,
Murdoch 6150, Australia, Tel: + 61432828016; E-mail: monizsheldon@gmail.com
Received June 02, 2019; Accepted June 19, 2019; Published June 25, 2019
Citation: Moniz S, Levy BB, Falconer T, Hird K, Breidahl W, et al. (2019) The Effect
of ACL Graft Size on Post-operative Knee Extension. J Trauma Treat 8: 447.
Copyright: © 2019 Moniz S, et al. This is an open-access article distributed under
the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and
source are credited.
The Effect of ACL Graft Size on Post-operative Knee Extension
Benjamin Levy B (MBBS), Sheldon Moniz (MBBS), Travis Falconer (MBBS, FRACS), Kathryn Hird (PhD, B App Sc), William Breidahl
(MD, FRANZCR) and Peter Annear (M.D, FRACS)
Fiona Stanley Hospital, 11 Robin Warren Dr, Murdoch-6150, Australia
Abstract
Introduction: Understanding factors that cause loss of extension post Anterior Cruciate Ligament (ACL)
reconstruction may assist surgeons in preventing this problem. The aim of this clinical trial is to determine the effect of
reconstructed ACL graft size on postoperative range of motion in ACL reconstruction in human subjects.
Methods: This therapeutic comparative cohort study consisted of a retrospective analysis of prospectively
collected data. Participants either received an autologous double bundle ACL graft (Control) or a combined
autologous/synthetic graft (Hybrid), which increased graft cross-sectional area. Femoral notch width was measured
preoperatively by Magnetic Resonance Imaging. Range of motion was determined using goniometry at two years post
reconstruction. Stepwise logistic regression and bivariate correlation was used to analyse data.
Results: 54 participants were included in analysis, 22 Control and 32 Hybrid. Hybrid group had a signicantly
larger reconstructed graft cross-sectional area (× (Hybrid)=71 ± 9.30 mm2; × (Control)=59 ± 12.26 mm2, t=4.76,
p<0.05). Mean notch size was smaller in Control group (1.83 ± 0.18 cm) compared to Hybrid group (1.91 ± 0.27 cm).
Hybrid group had signicantly fewer cases of postoperative knee extension loss (χ2=3.90, p<0.05), dened as loss
of passive range ≥ 3° at 2 years post-surgery. Increased graft cross-sectional area was not a signicant predictor of
loss of extension. There was also no relationship between notch width and extension range of movement. (r=0.01,
p=0.80).
Conclusion: A 20% increase in ACL graft cross-sectional area was not a signicant predictor of postoperative
extension loss.
gra options [9]. Upsizing the gra may also compensate for the
proposed increase in failure of the implanted gra during early gra
maturation [10].
e use of allogra in ACLR has also been studied. It is shown,
in a caprine study, that allogra in ACLR signicantly reduced cross-
sectional area when compared to patellar tendon autogra at 6 months
post reconstruction [11]. It could be hypothesised that this reduction in
size may confer a commensurate reduction in gra strength also found
those receiving autogra ACLR were twice as likely to suer from LOE
when compared to those receiving allogra [12].
Presently, the extent to which an ACL gra can be upsized before
causing LOE problems is unknown. While the eects of varying gra
sizes are reported in the literature there is a paucity of prospective
clinical studies that assess the eect of gra size on LOE. To our
knowledge no comparative study between two dened gra sizes in
human ACLR has been published previously.
Between August 2008 to October 2010 the senior surgeon conducting
this study changed his practice from oering patients a standard four-
strand hamstring double bundle autogra to oering the same gra
with a prosthetic LARS gra augment (Ligament Augmentation &
Reconstruction System 133 L0130605, Arc Sur Tille, France). is
added approximately 9 mm² cross-sectional area to the total gra
bundle. is represented an average increase of approximately 20% to
the cross-sectional area of the gra. e objective of this gra construct
Page 2 of 7
Volume 8 • Issue 2 • 1000447
J Trauma Treat, an open access journal
ISSN: 2167-1222
Citation: Levy BB, Moniz S, Falconer T, Hird K, Breidahl W, et al. (2019) The Effect of ACL Graft Size on Post-operative Knee Extension. J Trauma Treat
8: 447.
• AMB-doubled semitendinosis and a synthetic LARS Ligament
Reinforcer 133 (L0130605, LARS®, Ligament Augmentation &
Reconstruction System, Arc Sur Tille, France).
• PLB-doubled gracilis
• e inclusion of a LARS augment added between 8.4 mm2 –
12 mm2 to the cross-sectional area (LARS was doubled in all
patients). is represented an average increase of 20% to the
total gra area
Surgical technique
All patients underwent primary double bundle hamstring ACL
reconstruction by the senior surgeon. Examination under anaesthesia
was performed to conrm the clinical diagnosis and MRI ndings.
Physical examination included Lachmann, anterior drawer and pivot
shi tests. Under high tourniquet the limb was positioned at 90 degrees
with thigh side-post and foot roll bar. All meniscal and chondral
surgical intervention was performed during the same operation, prior
to ACLR.
The tendons were harvested through a 3 cm transverse incision
centred 1 cm proximal to the maximal bulge of the pes anserinus.
The individual tendons were slung through a 20 closed loop
endobutton with the tails whip-stitched to themselves using 1 vicryl
suture over the distal 3 cm. The diameters were measured in 1 mm
increments with tubular sizers and then were pre-tensioned using
the Acufex Graftmaster™ (Smith & Nephew, Inc., Andover, MA,
USA) at 20 Ib.
All patients received an ACL stump remnant retention technique
preserving all stable tibial ACL remnant tissue. e AMB position was
marked and drilled at the 10:30 clock position (le knee) 5 mm o
the back wall of the notch at 90° exion. e postero-lateral bundle
(PLB) position was marked and drilled 8 mm distal and posterior to the
AMB position approximately 5 mm o the articular cartilage. Existing
bundle footprints were used to conrm tunnel position. e femoral
tunnels were prepared for endobutton xation drilling through an
accessory inferior-central medial portal with the knee in hyper exion.
e viewing portal was routinely the lateral portal throughout the
procedure unless vision was dicult in which case accessory medial
portal was used. e tibial tunnel positions were placed within the
tibial footprint using the preserved remnant envelope as a guide. e
AMB position was identied drilling to an elbow target jig set at 60°,
positioned in the centre of the stump 8 mm from the anterior margin
of the remnant, drilling start point 1 cm medial to the tibial tubercle.
e PLB was drilled to the jig placed at the postero-lateral margin of the
tibial footprint drilling start point on the tibia at the anterior margin
of the medial collateral ligament. e PLB gra was placed before the
AMB. Both gras were tensioned manually through 15 knee cycles.
Gra was tensioned in exion (AMB 45°, PLB 20°).
ACL gra type and size was determined by referring to the
patients’ intra-operative records. e diameters were measured in
1 mm increments with tubular sizers using the Acufex Gramaster™
(Smith & Nephew, Inc., Andover, MA, USA). Standard geometric
calculation was used to convert this measurement to a cross sectional
area calculation in millimetres square. e total area of the Control
and Hybrid gras was calculated by the addition of the AMB and PLB.
Patient data included gender, age at the time of surgery, side of injury
and post-operative ROM (both exion and extension).
was to take advantage of the initial stiness and strength of the LARS
gra whilst the native autogra was undergoing early revascularisation
and ligamentisation in order to facilitate safe accelerated rehabilitation
(running in two months, Return To Sport (RTS) in 4-6 months) whilst
minimising the risk of gra stretch and early failure.
e aim of this observational prospective cohort study was to
compare knee LOE at two years post ACLR in a Control group of
patients who received a four-strand HS ACLR against a treatment
group (HYRBRID) who received a combined HS/LARS gra. e
relationship between patient age and MRI measured intercondylar
notch size on LOE was also assessed. It was hypothesised that the
Hybrid group would have higher rates of LOE due to increased gra size.
Methods
Study participants
Between August 2008 and October 2010, 147 patients prospectively
identied as eligible for enrolment. 88 of the 147 participants identied
as eligible met exclusion criteria or did not consent for participation. 59
participants were included in the study and underwent primary ACLR.
Exclusion criteria included patients with open growth plates, previous
surgery including ACLR to either knee, varus thrust gait, requiring of
a concomitant ligament surgery or having a compensable injury. One
participant was excluded from analysis as no data was available for the
area of their replacement gra. An additional four participants were
excluded from analysis as they were lost to follow up and as a result no
LOE records were available. is resulted in a total of 54 participants
analysed within the study (Figure 1).
Informed consent was obtained from all individual participants
included in the study. All procedures performed in studies involving
human participants were in accordance with the ethical standards of
the institutional and/or national research committee and with the 1964
Helsinki declaration and its later amendments or comparable ethical
standards.
Study parameters
is observational study was designed to investigate patients
returning for testing as part of a larger cohort study to evaluate the
clinical outcomes of the Hybrid gra conguration [13]. It was a
retrospective analysis of prospectively collected data. Data collected
included gender, age at the time of surgery, side of injury, size of
intercondylar notch and post-operative ROM (both exion and
extension). Primary outcome was LOE at 2 years.
Gra types
Patients were oered two ACL gra congurations: four-strand
hamstring (4SHS) (Control) or 4SHS with an added prosthetic ligament
(Hybrid). Patients were invited to choose their preferred gra based
on a standard pre-operative consultation and information. Of the 59
consented participants, 34 chose Hybrid and 25 chose Control gras.
Gra Type 1 (Control):
• Double bundle hamstring autogra gra
• Anteromedial Bundle (AMB)-doubled semitendinosis
• Posterolateral Bundle (PLB)-doubled gracilis
Gra Type 2 (Hybrid):
• Double Bundle hamstring autogra gra with LARS augment
Page 3 of 7
Volume 8 • Issue 2 • 1000447
J Trauma Treat, an open access journal
ISSN: 2167-1222
Citation: Levy BB, Moniz S, Falconer T, Hird K, Breidahl W, et al. (2019) The Effect of ACL Graft Size on Post-operative Knee Extension. J Trauma Treat
8: 447.
Range of motion
LOE was dened as loss of passive range ≥ 3° at a minimum of 2
years post-surgery. is measurement was compared to an anatomical
0°. Failure to achieve full range was inferred if manipulation under
anaesthetic or arthroscopic notchplasty was performed prior to two
years post-surgery. A single, blinded experienced physiotherapist took
ROM measurements with the patient in supine position with heel
support using goniometry. e anatomical landmarks used were the
prominence of the external surface of the greater trochanter, the lateral
epicondyle of the femur and the distal apex of the lateral malleolus [14].
Rehabilitation and follow up
e Control and Hybrid groups underwent dierent rehabilitation
regimes. Details of rehabilitation regimes can be found. Follow up
consisted of clinical consultation at 2 years at which point LOE
measurements were taken (Figure 2).
MRI measures
Magnetic resonance imaging (MRI) was used to determine the
width of the intercondylar notch. e images were obtained prior to
surgery on a 1.5T MRI (GE medical systems LX platform, Milwaukee,
Wis) utilising a dedicated 8 channel knee coil. e image used for the
measurements was from a coronal T2 fat suppressed sequence (TR
4000 ms, TE 85 ms) with a FOV of 14 cm, slice thickness of 3 mm with
a slice gap of 1 mm and a 256 × 192 matrix. Notch width was measured
at the point where the ACL and PCL intersect which approximately
represents the mid-point of the tibial spine. Establishing a common
point of reference allowed for the standardisation of measurement
between patients. Linear measurements were calculated by generating
a line from the apex of the lateral meniscus to the apex of the medial
meniscus (Figure 3). Line B was then drawn from the highest point
in the roof of the intercondylar notch to line A. Line C represents
the width of the notch and was obtained by measuring the distance
between the two femoral condyles at the point which bisects line B
and runs parallel to line A. Notch width was measured from the inner
surface of the identied cortical bone; a method of measurement that
is accurate when compared to corresponding cadaveric anatomy [15].
Notch width was not objectively measured intra-operatively.
Data management and analysis
Data were gathered and statistically analysed using Statistical
Package for the Social Sciences 21.0 for Windows (SPSS, Chicago, IL).
LOE is a dichotomous variable and therefore logistic regression was
used to compare groups. e level of signicance was set at p<0.05.
e statistician for the University of Notre Dame assisted in all areas of
statistical analysis on behalf of the study group.
Results
Descriptive and comparative statistics
Demographic data on the 54 patients included in the analysis
can be found in Table 1. Participants were aged 15-57 at the time of
ACLR. Mean age was 26 in the Control group and 31 in the Hybrid
group. e Control group was 50% male and the Hybrid group 62%
male. Chi-Square analysis indicates that there were no signicant
dierences between the Control and Hybrid groups with regards to the
side of operation (le/right; χ²(1)=0.11, p=0.74) or gender (χ²(1)=0.83,
p=0.36). Similarly, there was no dierence between the two groups
with regards to age (t (52)=-1.41, p=0.17).
ere was no dierence between the two groups with regards to
Notch Size (t (45)=-0.81, p=0.42). However, the Hybrid group did
receive a signicantly larger area of reconstructed gra (t (52)=-4.41,
p<0.001) consistent with the surgical technique received. Eleven of
the 54 participants (20.4%) were found to have study dened LOE, 7
(31.0%) in the Control group and 4 (12.5%) in the Hybrid group. ese
results are displayed in Table 2.
A total of ve participants required notchplasty to correct their
extension decit and two patients experienced frank gra rupture.
Contrary to initial predictions, Chi-square analysis demonstrated that
the Hybrid group had signicantly fewer cases of post-operative knee
extension loss (χ2(1)=3.90, p<0.05, N=55).
Logistic regression analysis
Logistic regression was used to establish the predictive power of
treatment group, age and total area (entered simultaneously as a single
level model) (Table 3). Nine of the 25 participants in the Control group
failed to have sagittal MRI views. As a result this variable could not be
included in regression analyses without substantial loss of validity. We
instead used bivariate correlation to determine notch width eect on LOE.
Analysis revealed that surgical group (Wald=3.88, p=0.049) was
a signicant predictor of LOE with the variable’s Beta weight (β=-
1.86) indicating that those in the Control group were 6.45 times more
likely (odds ratio) to experience extension loss than those receiving
the Hybrid gra. Age of the patient at the time of surgery was also
found to be predictive of LOE (Wald=4.04, p=0.04) with the odds of
experiencing extension loss being 1.07 for every year of age (β=0.07).
e mean age of those with LOE was 34 years compared to the mean
age of those with full available range of 25 years, supporting the above
nding that older age was associated with a greater incidence of
LOE. Notably, total gra area was not found to be predictive of LOE
Group Age Gender Side
Mean St. Dev % Male Left Right
Control (N=22) 26.9 11.3 50.0 12 10
Hybrid (N=32) 31.3 11.3 62.5 16 16
Table 1: Age, gender and side of operation (left/right) separated by group type
(Control/Hybrid) for all. 54 patients included in the nal analysis.
Group No. LOE LOE (%) Notch Size Graft Area
Mean St. Dev Mean St. Dev
Control (N=22) 7 31.0% 1.8 0.2 58.6 11.3
Hybrid (N=32) 4 12.5% 1.9 0.3 71.1 9.4
Table 2: Extension loss, notch size and graft area (mm2) statistics separated by
group type (Control/Hybrid) for all 54 patients included in the nal analysis.
Variable βS.E. Wald df Signicance Exp (B)
Group 1.86 0.95 3.88 1 p=0.05 6.45
Age 0.07 0.03 4.04 1 p=0.04 1.07
Graft Size 0.02 0.04 0.22 1 p=0.64 1.02
Constant -1.82 2.11 0.74 1 p=0.39 0.16
Table 3: Logistic regression output including Beta weights, standard error, Wald
statistics, signicance and odds ratios, for three predictors of extension loss
following ACL reconstruction.
Group Original n Missing Data n Final n
Graft Area Notch Width Extension Loss
Control 25 1 7 2 22
Hybrid 34 0 2 2 32
Total 59 1 9 4 54
Table 4: Number of patients with missing data across a range of variables relevant
for logistic regression.
Page 4 of 7
Volume 8 • Issue 2 • 1000447
J Trauma Treat, an open access journal
ISSN: 2167-1222
Citation: Levy BB, Moniz S, Falconer T, Hird K, Breidahl W, et al. (2019) The Effect of ACL Graft Size on Post-operative Knee Extension. J Trauma Treat
8: 447.
(Wald=0.22, p=0.64). While individual variables reached signicance,
the overall model only approached signicance according to the block
chi-square statistic (χ²(3)=7.74, p=0.05); demonstrating a Cox & Snell
pseudo R2 of 0.13 and a Negelkerke pseudo R2 of 0.21 (suggesting the
complete model accounts for about 21% of the total variance of factors
leading to extension loss). e model tested here, including three
predictors (age, gra size and group) correctly predicts the existence
(or non-existence) of extension loss in 83.3% of the patients in the
present study (an increase of 3.7% predictive accuracy over a null
model with no predictors).
Figure 1: Flow chart of patient inclusions and exclusions resulting in 54 patients undergoing nal analysis.
Figure 2: Comparison of rehabilitation protocol comparison.
Page 5 of 7
Volume 8 • Issue 2 • 1000447
J Trauma Treat, an open access journal
ISSN: 2167-1222
Citation: Levy BB, Moniz S, Falconer T, Hird K, Breidahl W, et al. (2019) The Effect of ACL Graft Size on Post-operative Knee Extension. J Trauma Treat
8: 447.
While Notch Width was not able to be included in the present
analysis as a result of missing data, nonparametric Spearman’s
correlation indicates that Notch Size was not signicantly related to
extension loss (r (50)=-0.16, p=0.29). e number of patients with
missing data is found in Table 4.
Discussion
e results in this study indicate no apparent relationship between
a 20% increase in the reconstructed ACL gra cross-sectional area and
the incidence of postoperative extension loss. Despite Hybrid group
having a larger reconstructed gra, logistic regression analysis revealed
the Hybrid group had signicantly fewer cases of post-operative knee
extension loss. is nding does not provide support for our initial
hypothesis that the Hybrid group would be more likely to experience
LOE and is contrary to the widely accepted paradigm. Regression
analysis also indicated older age was associated with a greater incidence
of LOE, in the sampled population. Bivariate correlation analysis
revealed no relationship between notch width and LOE. e results of
the current study suggest increasing four strand hamstring gras by
20% may be safely performed to create larger, stronger gras, which
may decrease the rate of gra failure.
A number of studies have investigated the clinical eect of
increasing gra size during ACLR. Biomechanical studies have found a
direct correlation between gra size and both resistance to stretch and
ultimate load to failure [9,16,17]. e use of larger sized gras has been
advocated to reduce the risk of gra rupture [16-18]. Additionally, a
signicant correlation between larger gra size and superior patient
reported outcomes [18,19]. Which employed a similar Hybrid
conguration to the current study using LARS gra to augment short
(<15 cm length) or undersized (3-4 mm diameter) semitendinosis gras.
Improved knee function scores were demonstrated with no increase
in risk of ligament rupture. Joint kinematics of ACL reconstructed
knees with gra sizes between 5-9 mm. Here, increased ACL gra size
was associated with substantially greater joint stability and decreased
articular cartilage contact pressures [20]. A similar inverse correlation
between ACL gra size and anterior-posterior tibio-femoral translation
was found [2,3]. is body of literature is compelling for the use of
increased gra size for improved stability and decreased gra failure.
To our knowledge previous studies evaluating gra size eect on LOE
have consisted of case series only, and therefore this study represents
the rst comparative cohort study that investigates eect of gra size
on LOE.
ere is evidence published to suggest gras can be excessively
large. According to a caprine study, larger gras were found to be
associated with a greater incidence of LOE [3]. is indicates a need for
balance between utilizing a gra with sucient cross-sectional area to
withstand the forces subjected on the ACL while concurrently ensuring
the gra is thin enough to allow unhindered ROM. e current study
suggests that it may be possible to increase the size of the ACL gra
safely without exposing patients to a greater risk of LOE. As described
in results, augmenting the autologous gra with LARS eectively
increased the total gra area between 8.4 mm²-12 mm² (approximately
20% increase in cross-sectional area for a gra 7 mm diameter). is
increase may fall below a critical threshold where gra-notch mismatch
does not occur. In the current study the gra size was increased by
adding a 9 mm2 LARS ligament, however upsizing could alternatively
be performed by tripling/quadrupling hamstrings, by adding allogra
or synthetic ligament. e results of this study suggest this can be
achieved without precipitating LOE. is is particularly relevant to
women, adolescents and shorter statured patients who are more likely
to have undersized harvest tendons [1,5,21].
In this study, a narrow notch size was not found to be a predictor
of LOE. Previous studies indicate a narrow notch size may be
associated with gra impingement and consequent LOE [22-24]. On
intra-operative identication of unfavourable notch morphology,
notch plasty can be performed to prevent impingement [25,26]. is
procedure however can lead to gra failure, abnormal gra forces,
increased anterior knee laxity and adversely aect articular cartilage
consistent with early degenerative disease [25-27]. Notch plasty also
removes osseous landmarks required for accurate tunnel positioning
and can cause possible regrowth/overgrowth of the notch in the
long term [28]. is literature reects the importance of choosing
appropriate gra size to avoid notch impingement and therefore may
alleviate the need for notch plasty.
e current study suggests older patients are at signicantly greater
risk of LOE. is nding was supported but refuted by the several other
studies in the literature reviewed [12,29-31]. It is hypothesised that
older patients may be less motivated to return to high-level sport and
therefore less likely to participate in rehabilitation programs aimed at
regaining ROM. Alternatively, age-related connective tissue changes
including decreased elastic properties of ligaments may account for the
results seen in the current study [32].
Overall extension loss in the current study was 21.8% at two years.
e literature shows signicant variation in the reported incidence of
LOE, ranging between 2-25% [12,31,33]. e discrepancy in reported
results may be attributed to inconsistencies in denition of LOE
between trials and thus is not consistently reported. e current study
denes LOE as a restriction in range of ≥ 3° which is more stringent
than previous studies [12,31]. is may account for the relatively
high incidence of LOE in the observed population. An additional
point of discrepancy between studies is the variability of follow up,
ranging between four weeks and one year [12,31,33]. A nal source
of inconsistency is whether previous studies chose to measure LOE
Figure 3: Coronal MRI showing the method of measuring intercondylar
width. Line A is drawn from the lateral meniscus to the apex of the medial
meniscus. Line B was drawn from the highest point in the roof of the
intercondylar notch to line A. Line (notch width) drawn at the point which
bisects line B and runs parallel to line A.
Page 6 of 7
Volume 8 • Issue 2 • 1000447
J Trauma Treat, an open access journal
ISSN: 2167-1222
Citation: Levy BB, Moniz S, Falconer T, Hird K, Breidahl W, et al. (2019) The Effect of ACL Graft Size on Post-operative Knee Extension. J Trauma Treat
8: 447.
against an anatomical 0° or the ROM in the contralateral knee. e
anatomical 0° method adopted by the current study fails to account
for patients who have up to 6° of physiological hyperextension [34].
However, anatomical 0° was chosen in this study as it more accurately
reects a decit that is likely to confer function loss.
Limitations
A notable limitation of the study was the heterogeneity in
management between the two treatment groups with regard to the
dierence in tensioning technique and the dierence in rehabilitation
protocols. Hybrid gras were tensioned in full extension whilst the
Control gras were tensioned at 45° (AMB) and 20° (PLB) of exion.
e impact of altering tensioning patterns has been shown to aect
post-operative knee kinematics and may have contributed to the
observed dierences in extension decits between groups [35]. e
rehabilitation protocols applied to the Hybrid and Control groups
were set as part of a larger cohort study designed to evaluate the clinical
outcomes of the Hybrid gra conguration (Figure 2). Superior initial
strength of the synthetic bundles of the Hybrid gras allowed for
aggressive early rehabilitation. e diering rehabilitation protocols
may have had an eect on the incidence of LOE. Intrinsic selection
bias may have been introduced due to patient selection of gra type. As
an observational study randomisation of gra type was not within the
scope of the study. Generalizability and reliability of results is limited
by the small sample size, from a single institution.
Conclusion
In the studied population there was no evidence to suggest a 20%
increase in the size of the reconstructed ACL gra or the size of the
intercondylar notch inuenced postoperative extension loss. Younger
patients and patients who chose and received a Hybrid gra were less
likely to suer postoperative LOE.
Competing Interests
e authors declare that they have no competing interests.
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Volume 8 • Issue 2 • 1000447
J Trauma Treat, an open access journal
ISSN: 2167-1222
Citation: Levy BB, Moniz S, Falconer T, Hird K, Breidahl W, et al. (2019) The Effect of ACL Graft Size on Post-operative Knee Extension. J Trauma Treat
8: 447.
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