Startup Invents Ratchet to Correct Adolescent Scoliosis

Rather than high-risk 6-hour operation leaving rigid spine, Apifix says its minimally invasive device leaves the backbone flexible.

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The ApiFix ratchet: Before and after.
The ApiFix ratchet: Before and after.Credit: ApiFix
Ruth Schuster
Ruth Schuster

Moderate adolescent scoliosis can be corrected through a long, high-risk operation that leaves up to 24 bolts in one's spine. Or it could be improved using a ratcheting device implanted through minimally invasive surgery invented by an Israeli startup.

Moreover, unlike the conventional surgical solution, the ApiFix device retains the spine's flexibility, says company co-founder and CEO Uri Arnin.

Treatments for curvature of the spine involve either a brace, for mild conditions – which doesn't cure the condition, but can stop it from worsening - or surgery. The standard operation implants up to two dozen bolts, which attach rods to the vertebrae to line them up.

The ApiFix device involves implanting two pedicle screws connected to a ratchet mechanism, that is activated by specific spinal exercises.

The more one monkeys with the spine – the more bolts one implants, the greater the potential for complications, not to mention infection. "Each bolt involves risk because each has to be implanted exactly right," says Arnin.

Scoliotic teens may appear to stand straight, but that's because they're compensating, unthinkingly creating a secondary bend to keep their head roughly in line with the pelvis. But x-rays show the S-shape of the spine, which just gets worse over time. (If the main scoliosis is treated, that secondary bend disappears, Arnin says.)

The ApiFix ratchet is suitable for non-severe scoliosis, of 40 to 60 degrees, which is the point at which braces just don't help. "Our device is essentially an evolution of the external brace," Arnin explains. "It's more efficient because unlike the external brace, it works 24/7."

Teenagers usually only wear the brace for some years but can, over time, stop using it. Potentially, the ApiFix internal brace could also be removed once the problem has been cured – but the company, founded four years ago, hasn't been around long enough for anybody to demonstrate the results of prolonged use. Meanwhile, most of the surgeries done so far have been successful, Arnin says.

So how does it work?

The concept is based on ratcheting – gradually, gently, coaxing the spine to reduce the magnitude of the curve and maintain the improvement.

The ratchet is screwed into the spine above and below the apex of the major curve, on the concave side of the deformity. The screw-implant connection is done using an eye joint, to enable angular adjustment. Thus, though the implant is rigidly attached to the bolts, polyaxial freedom can be maintained.

After two to three weeks' rest from the operation, the patient begins physiotherapy: simply bending sideways in the corrective direction – causing the ratchet to correct, each time clicking a step. This is repeated over weeks until the correction to the spine is satisfactory.

Theoretically, the ratcheting mechanism could be locked to make the spine rigid, if there were reason to do so, Arnin says. He hasn't encountered a reason yet. Nor has he encounter over-correction, but if that should happen, and the world is a place of infinite possibilities, it could be amended by shortening the device's rod using the control shaft. 

Several years after receiving European CE mark 2.5 years ago for use, ApiFix's technique to treat adolescent idiopathic scoliosis is used in several European countries, including Germany and France, and has now received the Israeli Health Ministry's imprimatur as well. ApiFix is in a process of obtaining FDA approval in the United States, and is working with the agency on defining the exact terms, Arnin says.

Theoretically, the ApiFix ratchet was designed to help young adolescents: It's usually between the ages of 11 and 18 that treatment decisions are made for them. The ratchet could be used to help adults in their 20s or 30s who shied from surgery in their teens - if their backs haven't become too rigid, says Arnin, a design engineer by profession. "That can easily be checked in x-ray. But it can't be administered to scoliotic patients with osteopenia" – reduced bone mass, he qualifies.

Apifix's other co-founder is Dr. Yizhar Floman, a spinal surgeon, who described the device in the professional literature: "Surgical management of moderate adolescent idiopathic scoliosis with ApiFix: a short periapical fixation followed by post-operative curve reduction with exercises."

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