Clinical Review

Active Robotics for Total Hip Arthroplasty

Am J Orthop. 2016 May;45(4):256-259

References

1. Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am. 2007;89(4):780-785.

2. National Joint Registry. National Joint Registry for England and Wales. 7th annual report. Available at: http://www.njrcentre.org.uk/njrcentre/portals/0/njr%207th%20annual%20report%202010.pdf. Accessed April 12, 2016.

3. Paul HA, Bargar WL, Mittlestadt B, et al. Development of a surgical robot for cementless total hip arthroplasty. Clin Orthop Relat Res. 1992;285:57-66.

4. Bobyn JD, Engh CA. Human histology of bone-porous metal implant interface. Orthopedics. 1984;7(9):1410.

5. Barrack RL. Dislocation after total hip arthroplasty: Implant design and orientation. J Am Acad Orthop Surg. 2003;11(2):89-99.

6. Miki H, Sugano N, Yonenobu K, Tsuda K, Hattori M, Suzuki N. Detecting cause of dislocation after total hip arthroplasty by patient-specific four-dimensional motion analysis. Clin Biomech. 2013;28(2):182-186.

7. Sugano N. Computer-assisted orthopaedic surgery and robotic surgery in total hip arthroplasty. Clin Orthop Surg. 2013;5(1):1-9.

8. Bargar WL, Bauer A, Börner M. Primary and revision total hip replacement using the Robodoc system. Clin Orthop Rel Res. 1998;354:82-91.

9. Honl M, Dierk O, Gauck C, et al. Comparison of robotic-assisted and manual implantation of primary total hip replacement: a prospective study. J Bone Joint Surg Am. 2003;85-A(8):1470-1478.

10. Nakamura N, Sugano N, Nishii T, Kakimoto A, Miki H. A comparison between robotic-assisted and manual implantation of cementless total hip arthroplasty. Clin Orthop Relat Res. 2010;468(4):1072-1081.

11. Nishihara S, Sugano N, Nishii T, Miki H, Nakamura N, Yoshikawa H. Comparison between hand rasping and robotic milling for stem implantation in cementless total hip arthroplasty. J Arthroplasty. 2006;21(7):957-966.

12. Hananouchi T, Sugano N, Nishii T, et al. Effect of robotic milling on periprosthetic bone remodeling. J Orthop Res. 2007;25(8):1062-1069.

13. Lim SJ, Ko KR, Park CW, Moon YW, Park YS. Robot-assisted primary cementless total hip arthroplasty with a short femoral stem: a prospective randomized short-term outcome study. Comput Aided Surg. 2015;20(1):41-46.

14. Nishihara S, Sugano N, Nishii T, et al. Clinical accuracy evaluation of femoral canal preparation using the ROBODOC system. J Orthop Sci. 2004;9(5):452-461.

15. Schulz AP, Seide K, Queitsch C, et al. Results of total hip replacement using the Robodoc surgical assistant system: clinical outcome and evaluation of complications for 97 procedures. Int J Med Robot. 2007;3(4):301-306.

16. Wyatt M, Hooper G, Framptom C, Rothwell A. Survival outcomes of cemented compared to uncemented stems in primary total hip replacement. World J Orthop. 2014;5(5):591-596.

17. Howard B. Is robotic surgery right for you? AARP The Magazine. December 2013/January 2014. Available at: http://www.aarp.org/health/conditions-treatments/info-12-2013/robotic-surgery-risks-benefits.html. Accessed April 12, 2016.

Attention is then turned to the acetabular portion of the procedure. Again, the robot must be rigidly fixed to the patient’s pelvis, along with the RM. Once the surgeon has registered the acetabular position using the digitizer, the robotic arm moves into the preoperatively planned orientation. A universal quick-release allows the surgeon to attach a standard reamer to the robot arm and ream while the robot holds the reamer in place. Once the acetabular preparation is complete, the cup impactor is placed onto the robotic arm and the implant is impacted into the patient. Thereafter, the digitizer can be used to collect points on the surface of the cup and confirm the exact cup placement (Figure 3).

Outcomes

The legacy system, Robodoc, has been used in thousands of clinical cases for both THA and total knee arthroplasty. The Table represents a summary of the THA clinical studies during a time frame in which only the femoral portion of the procedure was available to surgeons.

Bargar and colleagues⁸ describe the first Robodoc clinical trial in the US, along with the first 900 THA procedures performed in Germany. In the US, researchers conducted a prospective, randomized control study with 65 robotic cases and 62 conventional control cases. In terms of functional outcomes, there were no differences between the 2 groups. The robot group had improved radiographic fit and component positioning but significantly increased surgical time and blood loss. There were no femoral fractures in the robot group but 3 cases in the control group. In Germany, they reported on 870 primary THAs and 30 revision THA cases. For the primary cases, Harris hip scores rose from 43.7 preoperatively to 91.5 postoperatively. Complication rates were similar to conventional techniques, except the robot cases had no intraoperative femoral fractures.

Several prospective randomized clinical studies compared use of the Robodoc system with a conventional technique. The group studied by Honl and colleagues⁹ included 61 robotic cases and 80 conventional cases. The robot group had significant improvements in limb-length equality and varus-valgus orientation of the stem. When the revision cases were excluded, the authors found the Harris hip scores, prosthetic alignment, and limb length differentials were better for the robotic group at both 6 and 12 months.

Nakamura and colleagues¹⁰ looked at 75 robotic cases and 71 conventional cases. The results showed that at 2 and 3 years postoperatively, the robotic group had better Japanese Orthopaedic Association (JOA) scores, but by 5 years postoperatively, the differences were no longer significant. The robotic group had a smaller range for leg length inequality (0-12 mm) compared to the conventional group (0-29 mm). The results also showed that at both 2 and 5 years postoperatively, there was more significant stress shielding of the proximal femur, suggesting greater bone loss in the conventional group.

Nishihara and colleagues¹¹ had 78 subjects in each of the robotic and conventional groups and found significantly better Merle d’Aubigné hip scores at 2 years postoperatively in the robotic group. The conventional group suffered 5 intraoperative fractures compared with none in the robotic group, along with greater estimated blood loss, an increased use of undersized stems, higher-than-expected vertical seating, and unexpected femoral anteversion. The robotic cases did, however, take 19 minutes longer than the conventional cases.

Hananouchi and colleagues¹² looked at periprosthetic bone remodeling in 31 robotic hips and 27 conventional hips to determine whether load was effectively transferred from implant to bone after using the Robodoc system to prepare the femoral canal. Using dual energy X-ray absorptiometry (DEXA) to measure bone density, they found significantly less bone loss in the proximal periprosthetic areas in the robotic group compared to the conventional group; however, there were no differences in the Merle d’Aubigné hip scores.

Lim and colleagues¹³ looked specifically at alignment accuracy and clinical outcomes specifically for short femoral stem implants. In a group of 24 robotic cases and 25 conventional cases, they found significantly improved stem alignment and leg length inequality and no differences in Harris Hip score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, or complications at 24 months.

In 2004, Nishihara and colleagues¹⁴ evaluated the accuracy of femoral canal preparation using postoperative CT images for 75 cases of THA performed with the original pin-based version of Robodoc. The results showed that the differences between the preoperative plan and the postoperative CT were <5% in terms of canal fill, <1 mm in gap, and <1° in mediolateral and anteroposterior alignment with no reported fractures or complications. They concluded that the Robodoc system resulted in a high degree of accuracy.