knee

Zimmer Computer Assisted Surgery techniques combine advanced computer technology with a surgeon's skills to help improve the outcomes of knee and hip replacement surgery.

CAS, also known as Surgical Navigation, is defined as a surgery that is performed using a computer as a guiding and validation tool. The same way a car navigation system guides a driver from point A to point B, Zimmer's surgical navigation system provides the surgeon with important information during a surgery.

The system provides precise positional guidance when removing damaged surfaces of bones, based on a patient's anatomy, and suggests the appropriate implant size to be used and helps to determine its correct positioning.

Benefits of Surgical Navigation for Knee and Hip Replacements
In addition to assisting the surgeon's intra-operative decisions during a hip or a knee replacement procedure, Zimmer CAS system can offer a number of additional benefits, including:

• Smaller incisions and increased visibility during the procedure to help achieve:
  • Less pain and a shorter recovery time for the patient¹
  • Shorter hospital stay^1,2
  • Less scarring^1,3 (5.1 inches to 3.5 inches)
• Less invasive techniques which are associated with:
  • Reduced bleeding and transfusion rates^3,13
  • Reduced risk of emboli during a knee replacement⁵
  • Less disruption of tissue⁶

It has been shown that surgical navigation can help to provide a more accurate alignment^7,8,9, of the implanted joint that can enhance its overall function^8,10. This, in turn, should provide the patient with:

• A longer lasting implant^8,10
• A reduced risk of dislocation after hip replacement⁸

The accuracy of implant positioning through the Zimmer CAS System should also help reduce the risk of leg length discrepancy^11,12 that can cause limping after a hip replacement.

If you and your surgeon have explored all non-surgical treatments for your joint problems, a partial or a total knee or hip replacement can help you relieve your pain and get you back to living an active life.

In addition to assisting the surgeon's intra-operative decisions during a hip or a knee replacement procedure, Zimmer CAS system can offer a number of additional benefits, including:

• Smaller incisions and increased visibility during the procedure to help achieve:
  • Less pain and a shorter recovery time for the patient¹
  • Shorter hospital stay^1,2
  • Less scarring^1,3 (5.1 inches to 3.5 inches)
• Less invasive techniques which are associated with:
  • Reduced bleeding and transfusion rates^3,13
  • Reduced risk of emboli during a knee replacement⁵
  • Less disruption of tissue⁶

It has been shown that surgical navigation can help to provide a more accurate alignment^7,8,9, of the implanted joint that can enhance its overall function^8,10. This, in turn, should provide the patient with:

• A longer lasting implant^8,10
• A reduced risk of dislocation after hip replacement⁸

The accuracy of implant positioning through the Zimmer CAS System should also help reduce the risk of leg length discrepancy^11,12 that can cause limping after a hip replacement.

If you and your surgeon have explored all non-surgical treatments for your joint problems, a partial or a total knee or hip replacement can help you relieve your pain and get you back to living an active life.

ZIMMER CAS Total Knee Replacement: Precise Intra-Operative Feedback for Uncompromised Results.

The innovative design of the ORTHOsoft^® TKR helps you achieve uncompromised surgical performances. ORTHOsoft's^® fast, single-point anatomy digitization and its customized workflow helps to incorporate the navigation in your everyday OR routine.

Intra-operative feedback on implant alignment and range of motion is integrated into your personalized profile and enables accurate intra-operative decisions. The software's navigation workflows are time-saving and include advanced soft-tissue balancing options.

It is broadly recognized that long-term outcomes of TKR depend mainly on the accuracy of implant positioning and restoration of the mechanical axis.⁹ The assistance of computer navigation has been conclusively proven to provide consistent and superior alignment of prostheses in TKR (Kamat et al. 2008).

Surgical navigation can also be beneficial to overcome reduced visibility of the operated area when performing MIS techniques. Together, those surgical technologies can greatly benefit patients and help them return to their normal activities after a TKR. Below are benefits of CAS that have been referenced in clinical literature: 

• Smaller incision and improved surgical confidence through image guidance during the procedure should help achieve:
  • Reduced pain and a faster recovery time for the patient¹ 
  • Shorter hospital stay^1,2
  • Reduced scarring^1,3  (5.1 inches to 3.5 inches)
• Less invasive techniques which are associated with:
  • Reduced bleeding and transfusion rates^3,13
  • Reduced risk of emboli during a knee replacement⁵ 
  • Less disruption of tissue⁶

More active patients are often concerned about going back to work or taking care of their loved ones after a knee or hip replacement.

Unicompartmental Knee Replacement is an alternative to total knee replacement. This procedure is indicated for individuals whose arthritis affects only one side of the knee (diagnosis of unicompartmental osteoarthritis); therefore, the surgery is usually performed on patients under 60.¹⁴

Studies on clinical outcomes and kinematics of a successful UKR indicated functions closer to a normal knee, information important to patients with a more active lifestyle.¹⁴

Reduced inpatient stays and an improved range of motion can be expected,¹⁵ which helps to achieve;

• Faster recovery^14,15
• Greater possibilities of practicing sports, enjoying hobbies or simply enjoying a social life without pain^14,15

What is a successful UKR and how can the ORTHOsoft Uni Knee Navigation assist?
Again, the literature highlights the accuracy of the implant positioning and that an optimal alignment is an important predictor of the surgical outcome and survivorship.¹⁵

The Zimmer CAS ORTHOsoft UKR navigation can help in guiding the surgeon and in overcoming reduced visibility in a small incision. Consequently, the patients can benefit from the advantages of MIS surgery and the surgeon can rely on the technology to help achieve a good positioning of the implant.

Computer-assisted navigation offers better visualization when calibrating the axis and can help to avoid overcorrection. Therefore, computer navigation seems to be useful feature in improving implantation techniques, long-term results, and patient outcomes.¹⁷

In fact, Keene et al. (2006)¹⁶ show that a surgeon achieved his planned alignment of a UKR implant on 87% of the cases with CAS, compared to 60% without it. Similar data on the increased precision of component positioning with computer assisted surgery system such as the Zimmer CAS ORTHOsoft UKR are discussed in the clinical literature.¹⁷

The ORTHOsoft Unicompartmental Knee Software is an innovative and reliable tool for helping the surgeon in accurately positioning the implant.

1. Dutton A.Q., YEO S.J., Yang K.Y., Lo N.N., & Chong H.C. (2008), Computer-Assisted Minimally Invasive Total Knee Arthroplasty Compared with Standard Total Knee Arthroplasty. A Prospective Randomized Study. J Bone Join Surg, 90-A:2-9.
2. Zanasi S., Minimally Invasive Computer-Assisted Total Knee Arthroplasty through a Subvastus Approach, (2006), Orthosupersite.com.
3. Coon T.M., Tria A.J., and Lavernia C., & Randall L (2005) The Economics of Minimally Invasive Total Knee Surgery, Semin Arthro, 16 :235-238.
4. Kalairajah Y., Simpson D., Cossey A.J., Verrall G.M., & Spriggins A.J. (2005) Blood loss after total knee replacement. Effects of computer assisted surgery. J Bone Join Surg Br, 87-B(11):1480-1482.
5. Kalairajah Y., Cossey A.J., Verrall G.M., Ludbrook G., & Spriggins A.J. (2006) Are systemic emboli reduced in computer-assisted knee surgery? A prospective randomized, clinical trial. J Bone Join Surg, 88-B(2):198-202.
6. Kennon R.E., Keggi J.M., Wetmore R.S., Zatorski L.E., Huo M.H., & Keggi K.J (2003), Total Hip Arthroplasty Through a Minimally Invasive Anterior Surgical Approach, J Bone Join Surg. Am., 85:39-48.
7. Kalteis T., Handel M., Bathis H., Perlick L., Tingart M., & Griftka J. (2006) Imageless navigation for insertion of the acetabular component in total hip arthroplasty. Is it as accurate as CT-Based navigation? J Bone Join Surg BR, 88B(2):163-167.8).
8. Skiorski J.M., & Chauhan S. (2003) Computer-Assisted Orthopaedic Surgery: Do we need CAOS? J Bone Join Surg,85-B:319-23.
9. Haaker R.G., Stockheim M., Kamp M, Proff G., Breitenfelder J, & Ottersbach A. (2005) Computer-assisted navigation increases precision of component placement in total knee arthroplasty, Clin Orthop. 433:152-9.
10. Noble P.C., Sugano N., Johnston J.D., Thompson M.T., Conditt M.A., Engh C.A. Sr, & Mathis K.B. Computer Simulation: How can it help the surgeon optimize implant position? CORR. 2003 Dec; (417):242-52.
11. Ganapathi M., Vendittoli P.A., & Lavigne M. (2008), Limb length and femoral offset reconstruction during THA using CT-Free computer navigation, CAOS Congress, February 7-9, Glasgow, UK.
12. Konyves A., & Bannister G.C. (2005), The importance of leg length discrepancy after total hip arthroplasty, J Bone Join Surg. 87-B(2):155-157.
13. Schnurr et al. (2010), The Effect of Computer Navigation on Blood Loss and Transfusion Rate in TKA, Orthosupersite.com.
14. Borus et al. (2008) Unicompartmental knee Arthroplasty,  J Am Acad Orthop Surg. 2007;15:9-18, Volume 16, Number 1, January 2008).
15. Cossey et al. (2005), The use of computer-assisted surgical navigation to prevent malalignment in unicompartmental knee arthroplasty,  The Journal of Arthroplasty Vol 20 No.1,p.21-34).
16. Keene G. et al. (2006), Limb alignment in computer-assisted minimally-invasive unicompartmental knee replacement, J Bone Joint Surg Br. 2006 Jan; 88 (1):44-8.
17. Buckup et al. (2007), Implantation and Navigation for a unicondylar knee system, Orthopedics vol. 30 Number 8, 66-69.
18. Ganapathi et al. (2007), Femoral Component Positioning in Hip Resurfacing With and Without Navigation, Clin Orthop Relat Res.
19. Olsen et al. (2010), A comparison of conventional guidewire alignment jigs with imageless computer navigation in hip resurfacing arthroplasty, J Bone Joint Surg. Am 2010 Aug 4;92(9):1834-41.
20. Cobb J.P. et al. (2007) Navigation reduces the learning curve in resurfacing total hip arthroplasty. Clinical Orthopedics related Res.
21. Confalonieri et al. (2008) Leg length discrepancy, dislocation rate, and offset in total hip replacement using a short modular stem: navigation vs conventional freehand, Oct;31(10 Suppl 1). pii: orthosupersite.com/view.asp?rID=35541.
22. Vogt P. Navigation beim Durom Cup: Ein erster Erfhrungsbericht.