Stephanie Benoit June 12, 2016

Dr. Matthew Allen, Professor of Small Animal Surgery at the University of Cambridge, was faced with a challenging case when he encountered Bella, a Romanian Bucovina shepherd dog. Bella was plagued by severe mobility problems, and her owner was initially referred to Dr. Allen to assess the feasibility of a knee replacement. However, due to the aggressive nature of a total knee replacement and the fact that the bone of Bella’s knee joint was only partly damaged, Dr. Allen tried to come up with a different approach.


Using Materialise Mimics, he segmented the CT scans of Bella’s knee to create a virtual 3D model of the bone. This model was then 3D printed at the University of Cambridge, so that Dr. Allen could plan the surgery. He used the solid models to decide which parts of the bone needed to be removed, and where the implant (that would replace the diseased bone) would fit. The models were also extensively used to explain the surgery to the owner of the dog, who, being a vet herself, was fascinated by the use of 3D technology in the procedure. The design of the implant was then send to BioMedtrix, a veterinary implant manufacturer in the United States, where the design was optimized and the definitive implant manufactured. Custom surgical guides were also designed and these were fabricated in Dr. Allen’s laboratory so that he had patient-specific 3D-printed guides to take with him into the operating theatre. These guides were used to ensure the accuracy of the bone cuts needed to remove the diseased bone and cartilage from Bella’s knee. The implant was secured to the bone with acrylic bone cement to provide for immediate stable fixation and early weight-bearing on the operated leg.

virtual knee model: partial knee replacement dog Mimics
The CT images of Bella’s knee were converted into a virtual 3D model using Mimics. The crater in the bone on the right side of the image represents the damage to Bella’s bone and overlying cartilage.

Although Dr. Allen has been familiar with Materialise Mimics for around ten years now, he has only recently begun using its 3D model generating capabilities to design surgical guides. In fact, Bella’s surgery has taken on a special significance, as this is the first time a 3D-printed guide has been used in a partial knee replacement of this type. In the future, he plans to use this combination of Mimics and 3D Printing technology to fabricate surgical implants as well as instrumentation.

3D-printed bone model: partial knee replacement dog
Image credit: itv NEWS

Bella has made an excellent recovery from surgery and is now almost six months past the operation. We hope that Bella continues to enjoy life with her new implant, and that Dr. Allen will continue leading the way for implementing Medical 3D Printing in animal surgery!

About Professor Matthew Allen

Prof. Matthew Allen - University of Cambridge

After graduating from the University of Cambridge with a veterinary degree and a PhD in orthopaedics, Prof. Allen pursued his research in animal orthopaedic surgery at Upstate Medical University in Syracuse and at the Ohio State University in Columbus, before accepting his current position as Professor of Small Animal Surgery at his alma mater, the University of Cambridge. His laboratory, the Surgical Discovery Centre, undertakes fundamental and applied research in bone cancer, total joint replacement, orthopaedic infection, surgical navigation and robotics.

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