Use Of Computer Navigation Research Articles

Computer Assisted Orthopaedic Surgery – CAOS

The use of computer navigation in orthopedic surgery allows for real time intraoperative feedback resulting in higher precision of bone cuts, better alignment of implants and extremities, easier fracture reductions, less radiation and better documentation than what is possible in classical orthopaedic procedures. There is no need for direct and repeated visualization of many anatomical landmarks (classical method) in order to have good intraoperative orientation. Navigation technology depicts anatomy and position of "smart tools" on the screen allowing for high surgical precision (smaller number of outliers from desired goal) and with less soft tissue dissection (minimally invasive surgery - MIS). As a result, there are more happy patients with less pain, faster recovery, better functional outcome and well positioned, long lasting implants. In general, navigation cases are longer on the average 10 to 20 minutes, special training is required and equipment is relatively expensive. CAOS applications in knee and hip joint replacement are discussed.

Radiostereometric Analysis: The Hip

RSA is the most accurate technique available to measure implant migration following total hip arthroplasty. Implant migration is an important predictor of long term fixation of uncemented and cemented femoral and acetabular components. Especially with a more recent interest in uncemented fixation continuous migration after 6 months intervals might be evidence of inadequate bone ingrowths. RSA has the benefit of picking up continous migration long before clinical failure will be evident and is therefore considered to be perfectly suited to evaluate new implant designs and implant coatings. It can also be used to evaluate the impact of hard surface bearings including metal-on-metal and ceramic-on-ceramic on bone in-growth and migration of uncemented components. In the future RSA might be an interesting tool to pick up decreased rates of aseptic loosening with the use of computer navigation within short term follow-ups.

Computer navigation assisted pedicle screw placement

目的 将计算机导航技术应用于临床椎弓根螺钉固定并做初步分析.方法 2004年 2～ 12月在计算机导航系统辅助下,对 30例患者 (年龄 18～ 60岁,平均 45.3岁 )共行 134枚椎弓根螺钉固定.结果手术顺利,未发生血管和神经损伤并发症,螺钉大小选择合适,固定位置 及方向准确.术中透视次数及手术室人员所受 X线辐射量明显减少.结论计算机导航辅助椎弓根螺钉固定是一项安全的手术,且手术精度高.

Computer assisted screw insertion into real 3D rapid prototyping pelvis models

Objective. Show the use of computer navigation in exact screw positioning in the different pelvic bones. Background. Computer assisted pedicle screw insertion in the spine is an established procedure. Screw fixation is also used in highly difficult pelvic and hip surgery (arthroplasty revision surgery and tumor surgery). Design. Insert as long screws as possible with computer navigation into the different bones of the pelvis and compare these results with a non-computer controlled method. Methods. The computer navigation was done with the system of Medivision (Oberdorf, Switzerland), the software was SurgiGATE 2.1. Optically controlled spine instruments and a special calibrated drill were used. The screw insertion with and without computer navigation took place in seven real rapid prototyping pelvis models matched by pairs. Three screws were inserted into the Os ileum, one into the Os pubis and one into the Os ischium. The length of the inserted screws were measured and compared using routine statistic methods. Results. The mean screw length with vs. without computer navigation was 8.9 vs. 5.7 cm in the Os ileum ( P=0.0001), 6.0 vs. 4.2 cm in the Os pubis ( P=0.01) and 4.3 vs. 3.9 cm in the Os ischium (not significant). Conclusions. The use of computer navigation allows for the insertion of longer screws into the bones of the pelvis (more exact positioning), which requires a more precise original point of entry and direction of the drill (vector). Relevance The insertion of fixation screws in highly difficult pelvic and hip surgery (revision arthroplasty, tumor surgery) are another field for the use of computer navigation.

Reduction in Variability of Acetabular Cup Abduction Using Computer Assisted Surgery: A Prospective and Randomized Study

Optimal orientation of the acetabular component of a total hip prosthesis is an important factor in determining the early and long-term result of a total hip arthroplasty (THA). Conventional positioning of the cup component is usually done using a free-hand method, or with the help of a mechanical acetabular alignment guide. However, these methods have proven to be inaccurate, and a great variation in orientation of the cup is found postoperatively. In this study, we wished to determine if the variability of the abduction angle of acetabular cups could be reduced with the use of computer navigation. The abduction angles of the acetabular components of three groups of 50 THAs were assessed. In the first group, a free-hand method was used to position the cup component. This group was operated in the period before we started using computer navigation for hip surgery. In the second group, CT-based computer navigation was used to plan and help position the cup. The third group consisted of 50 THA cases in which a free-hand method was used to position the cup, although these procedures were performed in the period after we had begun using the Computer Assisted Surgery (CAS) system. The variability in cup abduction angle was assessed in all three groups and compared. There was a significant reduction in variability in the CAS group compared to the first group. There was also a reduction in variability in the CAS group compared to the third group, although this was not statistically significant. It is concluded that the use of computer navigation helped the surgeon to place the cup component with less variability of the abduction angle, and, more importantly, we found that no cups were placed in the more extreme positions (outliers).