CAOS aims to allow surgeon a degree of precision not possible with conventional means. Accurate positioning of implants may lead to: -
* Longer life of the implant It is likely that not positioning implants in a way that distributes the forces across the joint uniformly leads to stresses both between the implanted components and between the implant and the bone. These stresses could lead to early failure of the replacement.
* Optimal range of movements By placing the implants so that they match the normal position of the joint in relation to the supporting soft tissue as closely as possible, a better range of movements may be achievable.
* Better joint alignment As arthritic joints wear out, they may get deformed. Navigation allows the surgeon to restore the alignment precisely. Leg length differences are less with Navigated surgery.
* Better stability One reason why joints may be unstable is because the implants are placed imprecisely, in relation to what is normal, and also in relation to the soft tissue tension. It is possible to reduce this imprecision with navigated surgery.
* Decreased possibility of a revision surgery By increasing implant survival and reducing failure because of improper positioning of implants or instability, the potential for a more radical revision surgery is reduced.
* Makes Minimally Invasive Surgery (MIS) more accurate This means that the quicker recovery that MIS may offer, is available with less risk of less than optimal implant position.
* Less Blood Loss, Less Fat Embolus These are complications that are possibly linked to passing a rod in the bone marrow space of a long bone such as the tibia or the femur. Navigated surgery, because it does not entail the
use of such rods, may possibly reduce these complications.
While our conferences may be sponsored by industry, our scientific programme and our activities are geared towards being independent of industrial pressures and bias. We also recognise that Navigated surgery is not for every one, and understand that currently most surgeons do not use CAOS. Our objective is to relay the scientifically verifiable evidence for (or against) navigation. On the whole modern navigated surgery is a safe procedure. The risks some feel may be: -
* Longer operation Navigated surgery involves a long period when the joint is "regsitered" before the operation actually starts. This may be offset by speedier subsequent steps, but for most surgeons, navigated surgery takes longer and increases the period of anaesthesia for the patient. With newer techniques and experience of the surgeons this difference in operative length is less, even zero in many cases.
* Potential for Fractures Often navigated surgery uses trackers that are drilled into bone. This has on very rare occasions caused fractures. It must be noted that even non-navigated surgery carries the risk of fracture
* "Garbage in garbage out" It is entirely possible that errors in registration will make the surgeon place the bone cuts and implants incorrectly. Training is required to achieve reproducibly good results. CAOS UK provides workshops and training for surgeons to help reduce errors.
* Benefits of navigation in the long term may be difficult to prove Conventional surgery has already got a high success rate. The improvement in implant life with navigation may not be apparent for some time. The longevity can be however estimated by laboratory stress studies. Evidence to date seems to favour navigaton.
