An Arthroscopic 3D Bioprinter for Minimally Invasive Rotator Cuff Tear Repair

PROJECT SUMMARY/ABSTRACT
Rotator cuff (RC) tears are common, affecting over 20% of the general population with prevalence increasing
with age. A common treatment method is arthroscopic RC repair surgery, where one of many different fixation
techniques are utilized to mechanically attach the torn rotator cuff tendon to the bone. However, there is still a
high incidence of retear – ranging between 30% to 94% - leading to instability of the joint, pain, potential repeat
repair surgery, and depending on severity of the tear, highly invasive total shoulder arthroplasty. Several causes
of RC tear repair failure exist including stress risers in the tendon due to sutures, insufficient reattachment of and
healing between the tendon and bone, mechanical instability, and poor quality of tissue. There is a need to
innovate in this field in order to develop new ways to mitigate the risk of tendon tear after arthroscopic RC repair
surgery. One potential solution is to design a system that targets improving upon the most common identified
failure modes. 3D bioprinting has emerged as a novel technique for fabricating structures with precise geometry
and user defined mechanical and biochemical properties. One limitation to the current class of handheld 3D
bioprinters being used for biomedical applications is that in their current form, they require direct access to the
tissue that is being treated, which necessitates a highly invasive, open procedure. Arthroscopic 3D bioprinting is
a potential high impact medical treatment, where structures with user defined geometry, mechanical properties,
and biologic components can be precisely applied to a damaged tissue in a minimally invasive manner. Using
an arthroscopic 3D printing system, a tendon can be “spot-welded” back down to the bone to provide a
continuous mechanical interface between the tendon and bone using a previously described Janus Tough
Adhesive (JTA) biomaterial. The objective of this proposal is to develop an arthroscopic 3D bioprinter to precisely
deposit bioinks to enhance the attachment of torn RC tendons to the bone. In Aim #1 we will construct an
arthroscopic 3D bioprinter with the following key design features: 1) JTAs will be deposited via extrusion, 2) light
will be focused at the tip of the nozzle to facilitate photopolymerization, 3) control of extrusion and polymerization
on the device handle, 4) replaceable cartridges, 5) sterilizable, and 6) no more than 7mm in diameter (standard
arthroscope geometry). We will evaluate the effect of printing parameters and JTA concentrations on 3D printed
structures. We will also perform a proof of principle demonstration in a cadaver. In Aim #2 we will evaluate how
and arthroscopic 3D bioprinted RC tear repair can enhance mechanical properties of the tendon-bone interface
in a rabbit model. An arthroscopic 3D printer will be used to “spot weld” the tendon back to the bone after a
traditional RC repair in a rabbit model to reduce the point loading of the tendon where the sutures are placed.
Load to failure of the repaired RC will be evaluated and compared to the gold standard (suture repair). These
are the foundational studies necessary to develop a new surgical tool to allow surgeons to incorporate minimally
invasive 3D printing strategies for augmenting mechanical and biologic properties in RC tear repair.

Grant Number: 5R21AR083046-02
NIH Institute/Center: NIH
Principal Investigator: David Berry