A new study out of Imperial College London shows that robot assisted partial knee replacement surgery is “significantly more accurate than conventional surgery.” The surgical robotic system used in the study was from the Acrobot Company Ltd, a spin-out from Imperial College London. “Acrobot” is an acronym for Active Constraint Robot. The system consists of two main components: a surgical planning software and the robotic arm, aka Acrobot® Active Constraint System. Company explains:
The device belongs to a class of products known as Surgical Navigation systems. In summary this consists of providing computer-assistance by tracking the spatial locations of tools and patient and depicting them against a pre-operative plan on a computer screen to be used by the surgeon as guidance.
The Acrobot® Navigation system improves on existing Surgical Navigation systems in that it provides tooling for soft tissue management and it enables a minimally-invasive surgical approach.
Acrobot® is an acronym for Active Constraint Robot. The first two letters also relate to the concept of accuracy. We use the expression Active Constraint to describe the materialisation of a control technology applied to a motorised programmable device. A tool mounted on the device is confined, by hardware and software, to a certain volume in space. The device does not move autonomously, although it could be programmed to do so; it reacts to the actions of the surgeon holding a handle attached to the device. It aids motion, if the surgeon is moving the tool inside an allowed spatial volume; it prevents motion outside this volume.
The technology has been successfully proven in clinic. A first series of clinical trials, involving 7 TKRs, took place in 2002. The proof of concept was fully established with an MHRA-approved prospective, randomised, double blind (patient and assessor), comparative clinical investigation which was successfully carried out during 2004. During the study, 13 unicompartmental knee replacements were carried out with the aid of the Acrobot® system, and 15 were performed conventionally. The study demonstrated that the Acrobot® system consistently and accurately enables the positioning of a prosthetic implant according to a surgical plan. 13 out of 13 Acrobot® cases were implanted within 2° of a desired orientation. Only 6 out of 15 conventional cases were implanted with this accuracy, with the worst case showing a deviation of 4.2° from the planned position.
One additional benefit derived from the study is that we have developed a methodology, based on very low dose CT scans, which enables accurate and quantitative measurement of surgical outcomes providing hard clinical data.
The prototype used in the clinical trial is Mark II of a series of devices. It consists of two main components: the Acrobot® head and a gross positioning device. The reason for the separate positioning device is that, for safety concerns, the Acrobot® head was designed to reach a reduced spatial volume and to have three degrees of freedom only.
Press release from the Imperial College London: Robot assisted surgery more accurate than conventional surgery…
The Acrobot Company homepage…