ACL surgeons may obtain better arthroscopic results with navigation

Computer navigation could reduce the 10% to 20% ACL revision rates now seen, a surgeon said.

Some surgeons are seeing much better outcomes with computer navigation of ACL reconstructions without changing the type of grafts or fixation they use.

According to Michael J. Fracchia, MD, who has used the technology for more than 2 years, the benefits include more accurate placement of tibial and femoral tunnels, better isometry and increased stability.

“The navigation adds only about 5 minutes and has a very fast learning curve,” he said. “It is very user friendly.”

Computer navigation can yield useful information about the diagnosis, rotational stability, anteroposterior (AP) instability and whether a notchplasty is needed to avoid graft impingement for all kinds of arthroscopic ACL surgeries, including revisions.

“One of the driving reasons to do navigation: You get a nice warm fuzzy feeling when, at the start of a case you start the case, you have 12 mm of anterior drawer and when finished you have less than 4 mm. It really makes you feel good that you obtained your goals and did something beneficial for your patient.” Fracchia said.

Finding landmarks

Fracchia, who uses Orthopilot ACL 2.1 navigation system (Aesculap), presented his navigation-assisted arthroscopic ACL repair technique at the 8th Annual Advances in Arthritis, Arthroplasty and Trauma. He begins by arthroscopically confirming the diagnosis, debriding the ACL, performing a notchplasty and harvesting the graft.

The next step is mounting two navigation arrays and fixing each of them with two pins placed percutaneously on the medial femoral condyle and upper half of the tibial shaft, respectively.

Using a navigated pointer, the surgeon palpates such extra-articular landmarks as the tibial tubercle, anterior tibial crest and medial and lateral tibial plateau.

Data acquisition

The computer then gathers knee kinematic data in flexion, extension and the full range of motion and tracks pre-reconstruction AP instability and rotational instability during a Lachman test.

Fracchia then obtains intra-articular landmarks such as the anterior fibers of the posterior cruciate ligament, the anterior horn of the lateral meniscus and medial tibial spine. He also acquires points of notch data used for real-time calculations of impingement risk.

“Arthroscopically, we also get the footprint of where we expect the ACL will live,” he said.

Tunnel locations

Before drilling the tibial tunnel, datas displayed on the computer screen turn green when the proper location is found. Surgeons can get more-specific on-screen tunnel views by entering radiographic data beforehand.

The femoral tunnel is drilled in the same manner and the navigation system supplies similar data about its location and distance from the back wall, as well as isometry and impingement risk.

Fracchia said he sees knee laxity (anterior drawer) drop from 15 mm to 5 mm intraoperatively and rotational stability drop by 35%.

With these high-tech features, navigation can improve results after a short training period. “At first you are not going to trust it, but after four or five cases you’re going to realize that this information is really worth something,” Fracchia said.

For more information:
Michael J. Fracchia, MD, can be reached at Long Island Bone & Joint LLP, 635 Belle Terre Road, Suite 204, Port Jefferson, NY 11777; 631-474-0008; e-mail: mfracchia@libones.com. He has indicated he is a paid consultant to Aesculap.
Reference:
Fracchia MJ. The ACL meets computer navigation. Presented at the 8th Annual Advances in Arthritis, Arthroplasty and Trauma. Sept. 27-30, 2007. Arlington, Va.