A 3D Printed Anatomically Pre-Contoured Plate for the Treatment of Y-T Humeral Condylar Fractures: A Feline Cadaveric Study

Simple Summary Y-T condylar fractures are intra-articular fractures of the distal humerus characterised by a central intercondylar split and proximal extension of the fracture line through both the medial and lateral epicondyles. Such fractures are rare in the feline elbow and are perhaps the most difficult to treat. Because of the non-perforated supratrochlear foramen, feline bicondylar fractures are often associated with high-energy trauma and usually involve comminution of the epicondylar region. The humeral condyle needs to be anatomically reduced and stabilised with a screw. Plates are then most commonly added to address the supracondylar portion of the fracture. Locking internal fixation, which eliminates friction between plate and bone, may offer advantages in the repair of humeral condylar fractures. Human anatomically pre-contoured locking compression plate systems have been used to repair distal humeral fractures in humans with good to excellent clinical results. The aim of this study was to describe the development of a 3D printed anatomically pre-contoured locking plate and the use of such a plate for the reduction and stabilisation of bicondylar humeral fractures in isolated feline forelimbs. The results obtained suggest that such a plate may have application in the stabilisation of complex Y-T humeral fractures in cats. Abstract (1) Background: Anatomically pre-contoured plates usually require only minimal or even no intraoperative contouring. For complex cases, such plates also assist the surgeon as an anatomical template during fracture reduction. In this study, we present our experience of using a 3D printing technology for the treatment of bicondylar humeral fractures in feline cadavers. (2) Methods: Surgeries were performed on 15 pairs of front limbs amputated at the scapula. The limbs were obtained from 15 adult cats without obvious pathology of the skeleton. After flexion of the elbow and subperiosteal elevation of the anconeus muscle, the humeral Y-T fractures were created using a bone chisel and mallet. A custom-made anatomically pre-contoured interlocking plate was used to reduce and stabilise the medial aspect of the humeral condyle to the humeral diaphysis. After reduction of the humeral condyle, a positional locking screw was then inserted from the medial to the lateral side and a straight 2.4/2.7 interlocking bone plate was used to stabilise the lateral part of the condyle to the humeral diaphysis. (3) Results: The length of the humerus ranged from 98.2 to 107.0 mm and did not differ significantly between the left and right bone. The diameter of the isthmus of the humeral condyle ranged from 5.2 to 5.5 mm and did not differ significantly between the left and right bone. In all 30 limbs, bicondylar fracture was accompanied by epicondylar comminution. In 7/30 limbs (4 left, 3 right) the fracture of the humeral shaft was also present. In the left limbs, the postoperative articular surface defect of the humeral condyle was small (<1 mm) in 11/15 cases, moderate (1–2 mm) in 2/15 cases and large (>2 mm) in 2/15 cases in which the condylar screw was incorrectly inserted. In the right limbs, the postoperative articular surface defect of the humeral condyle was small (<1 mm) in 14/15 cases and moderate (1–2 mm) in 1 case. (4) Conclusions: 3D printing and the technology of metal powder sintering offers a wide range of possibilities for the development of new surgical implants. The anatomically pre-contoured bone plate appears to be a valuable tool in the reduction and stabilisation of Y-T humeral fractures in adult domestic cats weighing 3.0 to 4.5 kg.