Minimally Invasive Computer Navigation Assisted Knee Replacement

Total Knee Replacement (TKR) surgery has today become a commonly performed and highly successful surgical procedure. Recent innovations have resulted in further improvement in early and long-term surgical outcomes. New implant designs provide greater and more normal range of motions. Better understanding of the role of the ligaments in the knee has resulted in improved joint stability.

The good news for patients is that; minimally invasive surgical techniques are constantly evolving and speeding up the rehabilitation process. All these developments have meant shorter hospital stays, less time on a walker and a quicker return to normal ways of life. Lesser post-operative pain and minimal scar (improved cosmesis) are the direct benefits of minimally invasive surgery

The latest and perhaps, the most exciting innovation with Computer navigation is that, it guides the surgeon through the entire process of implantation of a total knee replacement. Through infrared sensing of patient’s anatomy, the computerised system precisely shows the surgeon the exact location where the new knee implants should be positioned. The technology promises to improve the short and long-term performance of the knee replacement.

Advantages of Computer Navigation Guidance in Knee Replacement Surgery

1. Incisions can be made smaller and the soft tissue dissection can be kept at a minimal level. The use of computer navigation, augments other minimally invasive surgical techniques resulting in greater protection of the quadriceps muscle and tendon during surgery. It is the protection of the quadriceps muscle mechanism that is the key component of minimally invasive surgery.
2. Studies show that bone cuts can be made more accurately and reproducibly when guided by computer navigation as opposed to other systems.
3. Computer navigation guidance eliminates the need for a rod to be placed inside the Intramedullary (IM) canal of the bone. Over the last two decades use of an IM rod has been a standard method for aligning cuts and was proved quite effective, but always had the chances of emboli from bone marrow cavity. In case of computer assisted knee replacement surgery this risk is eliminated and it is safer also for patients with cardiac ailments, high obesity, diabetes and hypertension.
4. Balancing the ligaments surrounding the knee has always been the most difficult and subjective part while completing of total knee replacement surgery. In a conventional surgery, the knee ligaments are balanced chiefly by the surgeons ‘sense and feel’ to determine, if the ligaments are appropriately taut. With computer navigation, ligament balancing can potentially be quantified to the nearest millimetre of ligament laxity or tautness.
5. In TKR surgery if there is significant deformity in the femur above the knee or in the tibia below the knee, then conventional alignment systems can prove to be difficult or impossible to use. This is because intramedullary systems requires an unobstructed bone canal. Similarly, if as a result of previous surgery any hardware such as plates, screws or rods are present in the bone blocking the bone canal, conventional alignment systems often do not work. With computer navigation systems, deformity and/or the presence of hardware poses no obstacle since access to the intramedullary canal is not a requirement. Thus, patients with bony deformity or hardware above or below the knee are ideal candidates for utilizing computer navigation guidance systems.
6. Studies have shown that computer navigation eliminates alignment “outliers”. Even Experienced surgeons using conventional alignment systems can accurately align the knee replacement in over 70- 75% of cases. However, studies show that in as much as 15–20% of surgeries, post-operative knee alignment will be less than ideal. These patients in this 15–20% group are considered “outliers”. It is felt that computer navigation’s accuracy can help the surgeon shrink this percentage of post-operative alignment “outliers”

Blog By

Dr. Chandrashekar P. 
MS (Orthopaedics), FIJS (Germany,
USA and Belgium), FISS (S. Korea)
Orthopaedics