We presented a simple technique to avoid graft tunnel mismatch. The rotation of graft inside the tibial tunnel is an effective way to deal with graft tunnel mismatch without having any negative effect on functional outcomes and graft rupture rate.
Graft tunnel mismatch is a common problem, in the present study, 32% of patients had longer graft. The reason for graft tunnel mismatch is the longer length of patellar tendon as compared to ACL[12, 13]. Another possible cause of graft tunnel mismatch is a creation of femoral tunnel using a far medial portal, which produces smaller femoral tunnel.
Graft healing inside the bone tunnel is a very important process as it can affect functional outcomes. BPTB graft heals early than soft tissue graft inside the bone tunnel as bone-to-bone union occurs early as compared to bone-to soft tissue union. Bone patellar tendon graft heals by primary bone healing, therefore, it is important to have sufficient bone-to-bone contact inside the tunnels. This technique is useful in increasing bone-to-bone contact inside the tibial tunnels without compromising graft tension. Another advantage of the present study was turning straight intra-articular graft into breaded structure. Breaded structure has more strength than non-breaded structures. Use of small length bone block or cutting the excessive bone or compromising on the tensioning of graft are some methods to counter the graft tunnel mismatch. However, with this technique, larger bone blocks can be used and graft can be tension adequately. Larger bone block will allow early and strong healing of graft inside the tibial tunnel. In the present study, functional outcomes, knee laxity, and graft rupture rate were comparable among two groups. Although these results reject the author's hypothesis, there is still scope for biomechanical study or cadaveric study to see the effect of braiding on knee stability.
Most of the previous studies about the minimum graft length inside the tibial tunnel were done using a soft tissue graft. Li Q et al. in their animal study reported that there is a delay in histological maturity and biomechanical strength if the graft inside the tibial tunnel is less than 15 mm. Currently, there is no literature available about the minimum required bone plug length inside the tibial tunnel. Therefore, there is no consensus regarding the minimum bone plug length inside the tibial tunnel. The present technique can help in achieving maximum bone-to-bone contact inside the tibial tunnel without compromising graft tensioning.
This study had some limitations: - Firstly, the number of patients in graft tunnel mismatch cohort was small. Secondly, a comparative study is needed that compared the patients with graft tunnel mismatch who underwent ACL reconstruction with smaller length bone plug and patients who underwent rotation of graft to maintain large bone plug.