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LEAD SUPERVISOR: Dr. Stephen Mellon, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences

Co-supervisor: Prof. David Murray, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences


Commercial partner: Stryker, Cork, Ireland

Bones are complex organs and their ability to withstand mechanical forces depends on a complex interplay of structural, architectural, and material properties. Complications in orthopaedic surgery are often related to the failure of a bone to withstand a mechanical force, e.g. a screw may pull out after transpedicular fixation, or a hammering action might cause peri-prosthetic femoral fracture during hip replacement surgery. Information about a bone’s structure, trabecular architecture and density can be readily gleaned from radiographic imaging but mechanical information about bone material is not normally available to clinicians.

We propose adding sensors to surgical instruments to collect measures such as torque on a drill, power-drawn by a saw and/or displacement/velocity as measured with surgical navigation. When this has been achieved, our primary hypothesis is that the sensor data has an association with bone mechanical properties such as strength, toughness, hardness and stiffness.

We will build a model that takes data from the instrumented tools and predicts the mechanical properties of bone. We will experimentally validate the model’s predictions in tests on cadaveric bone. We will also investigate the ways in which information about bone mechanical properties can be used to tailor surgery to an individual’s needs to avoid complications like fracture and loosening and to improve outcome.

It is envisaged that this patient-specific bone-property information could, in the future, become an important part of the clinical decision-making process, for example, “is the knee bone in this patient strong enough to do cementless surgery?” or “will this fracture fixation plate stay in place long enough for the fracture to heal?”.

This project will be conducted as a collaboration between the Oxford Orthopaedic Engineering Centre (OOEC, NDORMS, University of Oxford) and Stryker Instruments Division at their Innovation Centre in Cork, Ireland. The supervision team comprises an engineer (SM) and an orthopaedic surgeon (DM) on the academic side plus an engineer from the industrial partner (KB). The academic side (OOEC) will benefit from access to Stryker’s expertise around orthopaedic instrument design and manufacture. Stryker will benefit from OOEC’s expertise of improving outcome for orthopaedic patients, particularly patients who have joint replacement.


Apply using course: DPhil in Musculoskeletal Sciences

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