Computer-assisted knee replacement aims for better angle.
Tiny infrared reflectors bristle at the tips of three pronged units that sprout like flowers from the trackers and other tools.

The curious baby blue devices are the key to a kind of surgical positioning system used to help surgeons align the leg bones in the course of implanting artificial knee and hip joints.

Redondo Beach orthopedic surgeon Albert Reff, for about a year, has been using the computer assisted Orthosoft system in most of the total knee replacements and some of the hip replacements he performed at Little Co. of Mary Hospital in Torrance.

Dr. Reff said that for him, the computer assisted system has largely replaced the traditional “mechanical jig” method that aligns the patient’s legs at the proper angle so that the new joint parts can be fitted to the bone ends.

The reflectors, grouped in threes on those prongs, bounce back the unseen light to the Orthosoft computer. By triangulating on the reflectors, the computer uses a special algorithm to calculate the relative position of the leg bones.

In a knee replacement, for example, it requires that one tracker be temporarily affixed to the shin bone and one to the thigh bone. Other tools are used by the surgeon to allow the computer to determine which part of the bones need to be shaved off to allow for the artificial joint implant to be attached.

In joint replacement, it’s all about alignment. Misaligned knee replacements are likely to cause more pain and wear out faster. Misaligned artificial hip joints are in jeopardy of dislocation, Dr. Reff said.

Dr. Reff said what the computer assisted system provides is a highly accurate alignment, better than can be achieved with the jigs and the human eye. “You have to have confidence in this tool and be able to trust what it’s telling you: Reff said.

So far he’s pleased with the computer assisted system’s performance. Patients seem to do better and get a good range of motion more quickly, he said.

Because the system visualizes the bones, even as they are still covered in tissue, it’s ideal for the trend toward minimally invasive surgery, Reff said.

Torrance resident Margaret Golakoff had her right knee replaced by Dr. Reff , using the Orthosoft system, about two months ago. She was under anesthesia, so she didn’t see the system in action, but she likes the results.

She was expecting a long and painful recovery. But before long, she was up and walking. “I can walk. I thought I would be in bed. I thought I would be housebound,” Mrs. Golakoff said.