Successful treatment of knee problems is helped by collecting as much information as possible about the diseased joint prior to forming a plan of treatment. The longevity of total knee prostheses is determined by typically on the right alignment (frontal, sagittal and axial) of the prosthetic components, soft tissue restoring and balancing the mechanical axis of the lower limb. Does computer-assisted total knee replacement make a difference? Let us find here.

Diagnosis of Knee Problems

Use of x-rays, a CT (computed tomography) scan, or an MRI (magnetic resonance imaging) will aid your doctor to identify the severity of the problem with your knee, and guide with planning a course of treatment and if a total knee replacement (TKR) is necessary, help with defining the specific type of replacement that will be used.

The early visit to your surgeon will possibly comprise routine knee x-rays. For a few of them, it will be done while you are lying on a table and others while you are standing if you are capable to do so. Conventional x-rays are most frequently used to clarify problems within your knee however do not essentially show the degree of damage to cartilage, soft tissue, and ligaments. For that reason, computer imaging may be demanded by your doctor for a more thorough and accurate look into your knee. For evaluation of the collateral and cruciate ligaments, the menisci, and the articular cartilage of the knee, MRI is ideal.

Arthritis and Computer Imaging

When a patient has osteoarthritis, a sequence of x-rays will record damage to bones within the joint and will show cartilage loss areas. For several patients, this is satisfactory information for the surgeon to continue with the knee replacement surgery. In other cases, the surgeon may choose to use additional imaging to recognize anatomic changes because of osteoarthritis. Both MRI and CT scans are useful in assessing the extent of changes in detail. These imaging tools display your anatomy in cross-sections, like slices of bread. Other irregularities that may be shown in an MRI comprise some forms of soft tissue damage. The MRI exam typically takes about 30 minutes.

In addition to damaging cartilage, osteoarthritis often leads to damage to bone structures. This destruction may comprise the growth of bone spurs or osteophytes which can break off and move easily in the knee joint causing pain and the incapability to move. Other bone changes that may happen include cyst formations and sclerosis. To best see bone structures in detail, your surgeon may order a CT scan. Sometimes in order to evaluate the meniscus, ligaments and cartilage of the knee, this exam is requested in conjunction with an injection of contrast media into the joint space before acquiring the scan. If so, you will most likely be asked to get up and walk around or otherwise exercise your knee after the injection to issue the liquid in your knee joint. A CT scan is also often requested for patients who are not able to undergo MRI studies.

Patient-Specific Implants and Instruments

In current years, computer imaging has been used in the expansion of customized patient instrumentation (CPI) and customized total knee replacement implants in an effort to further enhance implant placement and alignment and the precision of surgical technique. This idea may draw upon pre-op imaging studies like MRI, x-rays, or CT scans that are operated in software programs to generate virtual 3D models of your knee joint and leg alignment. The digital recreation of your knee is then used to make customized cutting jigs that exclusively fit your anatomy. In a few cases, the information will be used to create a custom-fitted implant that will substitute your natural knee.

As far as exactness of implant alignment and positioning are concerned, studies show that the use of preoperative computer imaging and the development of customized patient instrumentation results in a greater incidence of exact implant alignment than that of traditional TKR alignment approaches.

As with any new medical technology, the use of computer imaging and the expansion of customized patient instruments and implants are more costly than traditional approaches and implants. If future studies show computer imaging and CPI adds considerably to increased patient satisfaction and implant longevity, the cost-benefit difference may cease to be a consideration.

Does it make a Difference at all?

It is normally believed that the use of computer-assisted navigation lets more accurate and reproducible restoration of component positioning and mechanical axis when compared with the conventional method.

Other benefits of navigation in TKR comprise enhanced restoration of the joint line, a decrease in perioperative blood loss, improved results in patients with extra-articular deformities and it has a significant role in surgical training. Disadvantages comprise an increased cost and longer operative time. Complications linked with navigation technique are rare and mostly associated with pin tracks.

Improved alignment should lead to an improved functional outcome and increased the long-term survival of the prosthesis. As noted before, several studies have shown a better function in the short and mid-term, while others found no major differences.

Conclusion

Many studies have demonstrated that there are no significant differences between the navigated and conventional TKR. Still, there is a lack of long-term data with regards to functional outcome and longevity of the prostheses. In the future, longer-term follow-up studies, improved imaging for assessing alignment and improved functional outcome evaluation scales should allow us to obviously outline the role of navigation in TKR.