gms | German Medical Science

Objectives/Interrogation: Previous research has shown that it is possible to synthesise a multiphasic bone-ligament-bone (BLB) scaffold similar to the dorsal scapholunate interosseous ligament (SLIL). This scaffold will facilitate regeneration of composite tissue and can be implanted for clinical use. The rabbit medial collateral ligament (MCL) has similar anatomical properties as the dorsal SLIL and thus, can be used as an animal model for testing this novel scaffold in vivo.

Methods: Multiphasic bone-ligament-bone scaffolds modelled from the dorsal component of the SLIL were 3D-printed with medical grade polycaprolactone (PCL). These simulated a BLB construct with two bone compartments bridged by aligned PCL fibres mimicking the architecture of the native ligament studied from cadaveric specimens. For surgical implantation, the native MCL of the rabbit was removed with holes drilled into insertion and origin points of the ligament on the femur and tibia using a 5 mm trephine. The bone compartments of the scaffold was press-fitted into the cavities and stapled in place. The rabbit knee joint was fixed in flexion using 1.4mm K-wires for 4 weeks prior to mobilisation for an additional 4 weeks. In total, 18 samples were implanted into 18 rabbits and harvested at four and eight weeks. Mechanical tensile testing (n=5 per group) and in vivo characterisation of the constructs were conducted.

Results and Conclusions: After 4 and 8 weeks in vivo, the scaffold remained intact. Mechanical testing of the BLB scaffolds showed that they were capable of withstanding normal SLIL physiological forces. After 4 weeks of mobilisation of the knee joint, the scaffolds improved in strength. In vivo study in the rabbits demonstrated that the scaffold was biocompatible and displayed good tissue integration and vascularisation. Upon implantation for 4 and eight weeks, bone formation and ligament remodeling was observed in the corresponding compartments.

Various tenodesis procedures for reconstruction of scapholunate instability fail to restore normal carpal kinematics. This research has demonstrated that it is feasible to fabricate a multiphasic BLB scaffold using additive manufacturing for dorsal SLIL reconstruction. Bone and ligament tissues were formed in their corresponding compartments with similar structural and mechanical properties to the native ligament. The artificial scaffold may provide an alternative to current techniques for reconstruction of scapholunate instability.