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but often explains often wide variation between series. For example in the non-elite athlete patients treated at Fortius Clinic, London, Andy Williams re-rupture rate is approximately 3% for hamstring ACL reconstructions. This is lower than Clatworthy’s rate above as the patients from the general public in London are overall less sporty than in New Zealand. Andy Williams practice also involves an abnormally high proportion of professional athletes. 50% of his ACL reconstructions are for this group. They are a very interesting group as well as very challenging. They are hard to lose to follow up such is their profile and the data available on the internet for those who subsequently move clubs. As a result, for coarse data such as graft re-rupture a 100% follow-up is to be expected. In addition they will test their surgery and any flaw will be shown up. In less demanding patient groups the chance of an operation apparently working will be higher and so it is harder to compare operative techniques amongst many aspects of surgery as no difference is likely to be found. Of the athletes treated by Andy Williams the footballers (soccer players) have the highest re-rupture rates. In studying ACL graft re-rupture from January 2001 until June 2013 he undertook 212 isolated (ie no other ligaments requiring reconstruction) ACL reconstructions on professional footballers. 6 were excluded (2 with patellar tendon allograft – both of which re-ruptured; and 4 patellar tendon grafts which were combined with a lateral tenodesis – all of which survived with return to full play). A minimum 2 year follow-up is presented below. Obviously with time more re-ruptures will occur in those cases quoted here still with surviving grafts at the time of follow-up, but in professional football re-rupture almost exclusively occurs within 12 months of surgery. In the case series mid-third patellar tendon graft is compared to quadrupled semitendinosis / gracilis graft, and the central femoral footprint position with that in the original AM bundle position. The tibial tunnel position was constant throughout entering the joint in the centre of the tibial ACL footprint.
These results are summarised in the table below:
AMB position
These findings are stark. In professional football in the United Kingdom, the overall re-rupture rate of quadrupled hamstring graft is higher than that for patellar tendon grafts (11% versus 8.6%) regardless of femoral tunnel position choice. The difference made by the choice of femoral tunnel position is still more dramatic: patellar tendon graft re-rupture a little more than doubles from 4.5% to 10.2% in the ‘anatomic’ central footprint group; but there is a huge rise in re-rupture if the hamstring grafts are considered – with approximately 2.5 times more in the central femoral footprint position (17%) compared to 6.9% in the AM position.
Discussion
In the mid 1990’s the transtibial ACL reconstruction technique was popularized. This resulted in a more vertical graft with a femoral tunnel that was often outside the native ACL footprint. This was combined with a posteriorly placed tibial tunnel, which enabled the femoral tunnel to placed at the back of the notch and avoided graft notch impingement.
The move to a central femoral tunnel placement, followed a period of popularity of double-bundle techniques and was based on anatomical studies showing a large femoral footprint that was more forward (distal) & lower (posterior) than the transtibially-drilled femoral tunnel.
Time zero biomechanical studies of a centrally placed graft showed better control of rotation than grafts placed outside the femoral footprint. It was proposed, therefore, that the central femoral graft position with its more normal knee kinematics would reduce the incidence of meniscal re-tears and further chondral damage and thus decrease the incidence of osteoarthritis.
Two clinical studies have evaluated this by comparing ACL grafts placed outside the femoral footprint with a centrally placed ACL graft.
In the MOON group study discussed above, it was shown that the TT group had a 1.8X higher rate of subsequent meniscal surgery and a 3.4X higher rate of chondral surgery six years post procedure.
CURRENT CONCEPTS
Quadrupled Hamstrings
Mid 1/3 Patellar Tendon
Overall Re-rupture
14 of 125 = 11%
7 of 81 = 8.6%
5 of 72 = 6.9%
1 of 22 = 4.5%
Central ‘anatomic’
9 of 53 = 17%
6 of 59 = 10.2%
05 Clatworthy Survival Curve Transportal vs. Transtibial ISAKOS NEWSLETTER 2015: Volume II 29