Background:
The purpose of computer assistance in a total knee replacement is to achieve optimal alignment, size, and positioning of the implant. The method is safe and accurate and may be particularly useful in cases with abnormal anatomy.
Description:
The classical computer-assisted system for total knee replacement was developed with real-time surgical navigation using infrared optical tracking arrays. The tracking arrays are attached to the tibial and femoral shafts, as well as to surgical tools, allowing the surgeon to move the tools relative to the knee. The computer-assisted systems allow the surgeon to combine the “measured resection” and “gap balancing” techniques.
Step 1: Preoperative planning. Set up the computer and software with the manufacturer implant features and personal preferences.
Step 2: Positioning and surgical exposure. Position the patient in order to optimize the camera view.
Step 3: Fixation of marker pins. Fix the marker pins to the tibial and femoral shafts.
Step 4: Registration of anatomical landmarks and mechanical axes. Move the limb and mark out the anatomical landmarks according to the instructions given by the computer.
Step 5: Adaption to the best model. Continue to register the joint surface and anatomy to adapt the fittest pre-registered model to the knee.
Step 6: Fine-tuning. The femoral and tibial components are adjusted in size, flexion, extension, rotation, slope, and positioning along the anterior-posterior axis.
Step 7: Navigation of cutting blocks and ligament balancing. The cutting blocks are positioned with the assistance of computerized navigation, adjusting for the mechanical axis and ligament tension. The cuts are then performed. Implant trials are inserted, and remaining soft-tissue releases may be performed assisted by the computer. Final implantation is performed.
Alternatives:
Conventional knee replacement using intramedullary rods as guidance.
Rationale:
The alignment and positioning of the implant are improved with the use of computer navigation1-5. Abnormal anatomy, anatomical variants and deformities, and presence of previous fractures are easy to manage with the precise assistance from the computer. Thus, in many cases, computer assistance may be a useful tool.
Expected Outcomes:
Computer-assisted navigation may optimize the precision and accuracy of the surgical procedure. Given the correct target, the outcome of total knee replacement may be more predictable with use of this tool; however, the impact on functional outcomes has not yet been proven to be clinically relevant in clinical trials, and the implant longevity has not been improved6-11.
Important Tips:
Use two 3-mm drill pins for fixation of the optical array to the tibia and femur.
If pins are placed within the wound (not through separate stab incisions), plan the positioning relative to the implant to avoid obstruction of the trials.
In severely osteoporotic patients, use bicortical fixation and handle the tissues and limb gently to avoid bumping or displacing the optical array as this will negatively alter the registration and reduce navigational accuracy.
Make sure the reflective beads on the optical array are clean at all times and remove them (if using clip-on beads) when using the saw to avoid blood splatter.
Train an assistant to press the screen buttons in the correct order and in accordance with the surgical progress.
Published outcomes of this procedure can be found at: J Bone Joint Surg Am. 2018 Aug 1;100(15):1265-74, and Acta Orthop. 2017 Apr;88(2):166-72.
Investigation performed at Haugesund Hospital, Haugesund; Hospital for Rheumatic Diseases, Haugesund; Lovisenberg Diaconal Hospital, Oslo; and Haukeland University Hospital, Bergen, in collaboration with Lærdal Hospital, Lærdal, Norway
Disclosure: The authors indicated that no external funding was received for any aspect of this work. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSEST/A295).
References
- 1.Petursson G, Fenstad AM, Gøthesen Ø, Dyrhovden GS, Hallan G, Röhrl SM, Aamodt A, Furnes O. Computer-assisted compared with conventional total knee replacement: a multicenter parallel-group randomized controlled trial. J Bone Joint Surg Am. 2018. August 1;100(15):1265-74. [DOI] [PubMed] [Google Scholar]
- 2.Petursson G, Fenstad AM, Gøthesen Ø, Haugan K, Dyrhovden GS, Hallan G, Röhrl SM, Aamodt A, Nilsson KG, Furnes O. Similar migration in computer-assisted and conventional total knee arthroplasty. Acta Orthop. 2017. April;88(2):166-72. Epub 2016 Dec 20. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Bäthis H, Perlick L, Tingart M, Lüring C, Zurakowski D, Grifka J. Alignment in total knee arthroplasty. A comparison of computer-assisted surgery with the conventional technique. J Bone Joint Surg Br. 2004. July;86(5):682-7. [DOI] [PubMed] [Google Scholar]
- 4.Chauhan SK, Scott RG, Breidahl W, Beaver RJ. Computer-assisted knee arthroplasty versus a conventional jig-based technique. A randomised, prospective trial. J Bone Joint Surg Br. 2004. April;86(3):372-7. [DOI] [PubMed] [Google Scholar]
- 5.Lüring C, Bäthis H, Tingart M, Perlick L, Grifka J. Computer assistance in total knee replacement - a critical assessment of current health care technology. Comput Aided Surg. 2006. March;11(2):77-80. [DOI] [PubMed] [Google Scholar]
- 6.Cheng T, Zhao S, Peng X, Zhang X. Does computer-assisted surgery improve postoperative leg alignment and implant positioning following total knee arthroplasty? A meta-analysis of randomized controlled trials. Knee Surg Sports Traumatol Arthrosc. 2012. July;20(7):1307-22. Epub 2011 Jul 6. [DOI] [PubMed] [Google Scholar]
- 7.Bauwens K, Matthes G, Wich M, Gebhard F, Hanson B, Ekkernkamp A, Stengel D. Navigated total knee replacement. A meta-analysis. J Bone Joint Surg Am. 2007. February;89(2):261-9. [DOI] [PubMed] [Google Scholar]
- 8.Longstaff LM, Sloan K, Stamp N, Scaddan M, Beaver R. Good alignment after total knee arthroplasty leads to faster rehabilitation and better function. J Arthroplasty. 2009. June;24(4):570-8. Epub 2008 May 19. [DOI] [PubMed] [Google Scholar]
- 9.Parratte S, Pagnano MW, Trousdale RT, Berry DJ. Effect of postoperative mechanical axis alignment on the fifteen-year survival of modern, cemented total knee replacements. J Bone Joint Surg Am. 2010. September 15;92(12):2143-9. [DOI] [PubMed] [Google Scholar]
- 10.Bellemans J. Neutral mechanical alignment: a requirement for successful TKA: opposes. Orthopedics. 2011. September 9;34(9):e507-9. [DOI] [PubMed] [Google Scholar]
- 11.Choong PF, Dowsey MM, Stoney JD. Does accurate anatomical alignment result in better function and quality of life? Comparing conventional and computer-assisted total knee arthroplasty. J Arthroplasty. 2009. June;24(4):560-9. Epub 2008 May 19. [DOI] [PubMed] [Google Scholar]