The most important finding of the present study was that, patients in whom ACL reconstruction was done using hamstring graft with preserved insertion, had significant number of players returning to same level of sports postoperatively. Also, there was a statistical significant correlation of hamstring free graft with graft rupture. However, the two groups were comparable in terms of mean follow up, arthrometricKT-1000 difference, Lysholm score, WOMAC score, limb symmetry index and return to sports.
Neuromuscular control is understood to play an imperative role in injury risk and has been recognised as the most amendable risk factor[31]. Neuromuscular training expedites alterations which improve pre and mid stance neuromuscular activation configurations, which decrease joint motion and prevents ACL injury from high pivoting loads sustained during sports[32]. A study by Hewitt et al states that even after ACL reconstruction the proprioception remains poor and is a major risk factor for re-injury of ACL[2]. Better proprioception leads to better neuromuscular control and thus helps in regaining pre-injury Tegner activity level post ACL reconstruction[33]. A prospective study by Gupta et al found better proprioception and hence neuromuscular control in patients treated with hamstring graft with preserved insertion than free hamstring grafts[16].
Lack of vascularity associated with free hamstring graft prone for graft failure during the initial phase of revascularisation which is absent in case of hamstring grafts with preserved insertion, as they remain vascular due to an uninterrupted supply from the tibial side with the help of inferior genicular artery[34, 35]. A randomised controlled study by Ruffilli et al observed that preservation of blood supply at tibial end restores the blood supply of graft post ACL reconstruction and helps in early ligamentisation of graft within the tunnel[36]. Further, they reported improved morphology of the graft within the tunnel compared to hamstring free graft, which confirms our finding of decreased graft failure in cases of hamstring graft with preserved insertion[36].
Tibial side fixation has been observed to be a weak link post ACL reconstruction as the vector of forces acts in the line of tibial tunnel[37, 38]. Further, tendon to bone healing at insertion site is superior to tendon fixation inside tunnel with screw as observed by various studies inpast[15, 16, 18–20]. As, the biological insertion at tibial side maintains the inherent strength, that is resistant to cyclical forces[15], we propose, hamstring graft with preserved insertion provides less chances of graft pull-out from tunnel. There was no graft pull-out from the tunnel in this study, adding to the debate of secureness of graft on the tibial side with preserved insertion grafts.
Though there has been tremendous improvement in understanding of techniques of graft harvest, fixation devices and biology of graft incorporation, there is very little literature mentioning the superiority within the hamstring graft types[34, 39, 40]. This study adds to the discussion on graft healing, maturation, the necessity for surgeons to objectively assess healing after ACL reconstruction and the benefits of an individualized surgery, including graft choice.
In the present study, both the groups were matched in terms of age, gender distribution, anatomical factors, intraoperative factors including femoral tunnel length, meniscal tear and chondral damage, side involved, hormonal factors, level of sports and mode of injury. Further, this study compared both the grafts in terms of graft failure, functional outcome, objective mechanical stability, and return to sports. To our knowledge, this is the first study of its kind, with such a long follow-up and optimum sample size, reducing the confounding bias to minimum, hence, reducing the dilemma existing with graft type to be used for ACL reconstruction.
There exists concerns of windshield wiper effect and Bungee-cord effect of graft with preserved insertion as fixation on the tibia side is away from aperture, though we didn’t observed this till the final follow-up of 5 years. Further, we have not calculated tunnel widening difference between 2 techniques which could have shed more light on graft incorporation within the tunnel.