We have to brace ourselves to face the aftermath of a rapidly aging population: with an exponential increase in patients suffering from osteoarthritis, of which the knee joint is the most commonly affected joint.
While early osteoarthritis can be managed with medication, physiotherapy and lifestyle modifications, knee replacements remain the only option for patients suffering severe osteoarthritis. A primary goal for knee replacement is the restoration of the normal alignment of the lower limbs.
Traditional techniques require a lot of visual judgement from surgeons, this is prone to error and significant malalignment was found in up to 30% of the knee replacements – this will significantly accelerate the wear and tear, eventually leading to premature implant failure.
With the aid of computer navigation, the anatomical landmarks of operated limbs are captured, and the alignment of the cutting instruments can be reflected in real time. Ligamentous balancing can be fine-tuned as well, by studying the kinematics of the replaced knee joint.
3D printing technology can also be used in knee replacement surgeries. Patients will undergo a pre-op MRI scan of the lower limb, allowing the sizing, positioning and alignment of the implants to be pre-determined. These 3D printed patient specific instruments (PSI) will fit onto the patients’ knee joint perfectly, and allow the surgeons to perform the knee replacements quickly and accurately.
There are other benefits to these techniques as well: reduced blood loss and reduced risk of embolic events, because the medullary cavity of the bone will no longer be violated (a requirement in traditional techniques).
Overall, “SMART” knee replacements are well established in many centres worldwide and have shown to improve their accuracy and results.
By Dr Henry Chan Ying Ho
Consultant, Department of Orthopaedic Surgery, Tan Tock Seng Hospital