Development of Novel Plasma Modified Metallic Materials for Anterior Cruciate Ligament Reconstruction

Anterior Cruciate Ligament (ACL) Rupture is one of the commonest injuries in Sports Medicine. The mainstay of treatment is Arthroscopic assisted intra-articular ACL Reconstruction, which is estimated to be done more than 100,000 procedures in US each year. Autograft reconstruction with bone-patellar tendon-bone autograft and hamstrings autograft are the two most popular and successful techniques at present. The graft is fixed to the bone tunnel by either suspensory device (e..g Endobutton) or anatomical device (e.g. interference screws). The initial mechanical strength provided by these implants is satisfactory. However, patients are still required to abstain from pivoting sports activity for six to nine months. Otherwise, instability may recur. Many surgeons believe that the problem of incorporation of the graft in the bone tunnel is one of the significant issues in leading to this prolonged time-out. It is therefore attractive to supplement an additional mechanical fixation to the implants by enhancing and accelerating biological fixation of the implanted interference screws to both the host bone (screw-host interface) and to the graft (screw-graft interface), while awaiting definite graft incorporation in the host bone tunnel. The researchers suggest a way in promoting biological fixation by modification of the surface characteristics of the currently used metallic interference screws using plasma immersion ion implantation technique.The researchers' previous work has demonstrated that the plasma immersion ion implantation (PIII) surface treatment is a feasible way to enhance and accelerate the osteoconductivity and bioactivity of implantable metallic materials. To address the problems associated with biological fixation in the bone tunnel, applying plasma immersion ion implantation (PIII) surface technology to modify the existing metallic interference screw surface is a potential way out. The present project aims to enhance and accelerate biological integration on metallic interference screws modified by plasma immersion ion implantation technique for Anterior Cruciate Ligament Reconstruction. The researchers shall conduct mechanical, biomechanical, short term and long term in-vitro and in-vivo biological studies on currently used metallic interference screws with plasma surface enhancement. If the outcome is favourable, it may enhance the future surgery of ACL reconstruction, benefiting patients worldwide, in particular to those professional sportsmen with ligament rupture, so that they can resume their training as early as possible.