CAD software holds promise fornew 3-D modeling applications

Med-Link targets orthopedic surgery market

The power of computer-assisted design (CAD) has been a provenasset in the automotive and aerospace industries. Now, an engineeringconsulting firm from San Dimas, CA, hopes to harness the technologyfor medical imaging applications.

The company, Dynamic Computer Resources, has modified an off-the-shelfsoftware package called I-DEAS Masters Series, made by StructuralDynamics Research of Milford, OH, to work with its own softwarefor converting CT and MRI data. The resulting software, dubbedMed-Link, can produce unique 3-D solid models that differ fromthose now used in medical imaging, according to Reagan Kee, directorof sales for Dynamic Computer Resources (DCR).

"Right now physicians are looking at 3-D models by takingMRI and CT scans into 3-D volumetric software and spinning thesemodels around," Kee said. "We found in talking to lotsof doctors that what they really want to do is move (the partscontained in these models) around and reattach them, all of whichis beyond the scope of simple visualization or imaging software."

Med-Link will probably be used first by surgeons to plan operations.In the case of a severely fractured leg bone, a 3-D model madewith the software will allow a surgeon not only to study thatbone on screen but also to call up a library of plates, pins andscrews to determine what hardware is best suited to fixing it.Most impressively, Med-Link can be used to predict surgical outcomes.

For example, a custom-made 3-D model showing the lower extremitiesand pelvis of a patient can be animated to give a visual representationof pre- and postoperative gaits.

"With this, we can determine the best method of correctingthe bony deformity and be able to predict postoperative gait implications,"said Dr. Richard Reynolds, an assistant professor of orthopedicsat the University of Southern California.

Med-Link also opens the door for medical consultations overlong distances, using images transmitted by telephone or satellite.

"By viewing simultaneous 3-D images, doctors are providedthe capability of discussing suggested surgical approaches withgraphical examples," said Dr. Daniel Antonelli of the MotionLaboratory at Children's Hospital Los Angeles.

Antonelli and his colleagues at Children's Hospital were amongthe prime movers in getting Med-Link developed. The physicianswanted a system that could provide them with more preoperativeinformation. DCR, as a consulting firm and value-added dealerfor software vendor Structural Dynamics Research, accepted thechallenge.

Ease of use is critical to Med-Link's acceptance by medicalpractitioners. The recognition of that fact led DCR to modifythe I-DEAS software to be appropriate for doctors.

"You really can't throw a computer-aided engineering packageat a physician," said Kee. "The surgeon needs some ofthose tools but not all of them."

In tailoring Med-Link for surgeons, the company limited thenumber of CAD tools that are displayed as icons on the screen,although all the CAD tools are available, if needed. The interfacewas also adjusted to make surgeons more comfortable.

The cost of Med-Link, which includes a high-performance graphicsworkstation made by Silicon Graphics, is $80,000. DCR chose theSilicon Graphics platform because of its speed and ease of use.DCR sells Med-Link in a software-only configuration for $28,000.

The primary market for the integrated system is the orthopedicsurgery market. But manufacturers of implants could also use itto customize devices for individual patients. With 3-D data, hipreplacements, artificial limbs and other prostheses would fitmore exactly, optimizing rehabilitation and comfort for the patient.Another market would be cosmetic surgery.

"We can use laser scans and get them into Med-Link andcompare a laser scan and CT scan to show what implants need tobe manufactured for surgical reconstruction," Kee said.