Effect of Calcium
Phosphate-Hybridized Tendon Graft in Anterior Cruciate Ligament Reconstruction:
A Randomized Controlled Trial

H, Kanamori A, Ikeda K, Hioki S, Kinugasa T, & Sakane M. American Journal
of Sports Medicine. 2012; 40:1772-1780. doi

cruciate ligament (ACL) reconstruction is performed regularly in the orthopedic
world with relatively favorable results. 
While the selection of a hamstring autograft allows for fewer issues at
the harvest site than the patellar tendon autograft, the problem that arises is
the lack of bone block to assure graft fixation and possible widening of bone
tunnels over time.  The purpose of this
randomized controlled trial was to assess the effectiveness of calcium
phosphate (CaP) graft hybridization to improve graft fixation in comparison to
a conventional single-bundle ACL reconstruction.  Sixty-four patients randomly received hamstring
allograft ACL reconstruction with either CaP (n = 32) or a conventional graft (n
= 32). Meniscal injury was collected and treated accordingly, there were no
differences between groups.  Surgical
methods and rehabilitation were identical for the two groups.  Patients were evaluated at 3 time points
(preoperatively, 1 year and 2 years post operatively).  Evaluation included a pivot-shift test (under
anesthesia), KT-1000 test, CT for tunnel
diameter, MRI, patient outcomes (i.e., Tegner activity, Lysholm, IKDC), and arthroscopic
examination of revascularization at the 1 year follow up (n = 54).  The CaP group had significantly less anterior
translation with a KT-1000 than the convention group at the 1- and 2- year
follow-up appointments, better Lysholm scores at the 2-year follow up, and less
tunnel enlargement (indicating better fixation) at the 1-year follow-up.  Other patient outcomes (i.e., Tenger, IKDC),
revascularization, and pivot shift results were not different between the two

it appears that this novel approach may have some benefits within the
orthopedic population. The hamstring autograft often has less graft site complications
than the patellar tendon, but can result in more tunnel enlargement and a
looser graft that may be more likely to fail. CaP involves soaking the
hamstring autograft in a solution to help encourage better fixation to combat
the lack of a bony block for fixation.  While
there were some favorable outcomes, it would be very interesting to follow the
results of this study for a longer period of time.  It is still a relatively novel approach that
should be further evaluated, including looking at the incidence of
osteoarthritis development.  Once an ACL
tear occurs, the priority becomes minimizing long-term issues such as
instability and osteoarthritis development. 
It may be critical to find an intervention to help improve longer-term
ACL reconstruction outcomes during the time of surgery.  It is interesting that meniscal status did
not affect outcomes in either group, as the meniscus is often times a
contributing factor to disability and degeneration.  Once a knee injury occurs, the pathway to
osteoarthritis is accelerated.  Some
physicians are starting to realize this, and start to investigate anecdotal and
novel techniques to be utilized at the time of injury or surgery, prior to any
structural changes occurring.  Has anyone
had an athlete who may have undergone the CaP hybridization?  Has anyone heard of any physicians trying

by: Nicole Cattano 
by: Stephen Thomas


Mutsuzaki H, Kanamori A, Ikeda K, Hioki S, Kinugasa T, & Sakane M (2012). Effect of calcium phosphate-hybridized tendon graft in anterior cruciate ligament reconstruction: a randomized controlled trial. The American Journal of Sports Medicine, 40 (8), 1772-80 PMID: 22713551