Custom 3D Printed Braces

A custom 3D-printed brace is a scoliosis orthosis manufactured digitally rather than by hand. Instead of taking a plaster cast of the trunk, the orthotist captures the body shape with a 3D optical scan, designs the brace on a computer using CAD/CAM software — placing pressure zones and expansion areas to suit the individual curve — and then produces the shell by 3D printing or computer-controlled fabrication. The finished brace follows the same corrective principles as a traditional TLSO; only the way it is designed and made is different.

The corrective mechanism is unchanged: pressure over the convexities, relief on the concavities, aiming at three-dimensional control of the curve. The advantages lie in the process. Digital design is faster and more reproducible than hand-casting, and it allows precise, repeatable adjustment. 3D-printed shells can be made thinner, lighter and sometimes more ventilated than conventionally moulded braces, which can improve comfort and discretion — and comfort matters, because a brace only works if it is worn. Some systems add finite-element computer simulation to predict and refine the correction before the brace is ever made.

A 3D-printed or CAD/CAM brace is an alternative way of manufacturing a brace for the same patients who would be candidates for conventional bracing: growing children and adolescents with progressing curves in the braceable range. The decision to brace, and the design goals, are the same; the choice of manufacturing method is made with the orthotist.

The evidence to date suggests that digitally produced braces perform comparably to conventionally made ones. Studies comparing CAD/CAM and 3D-printed braces with traditional plaster-moulded braces have found broadly similar in-brace curve corrections and similar effects on postural stability, with the digital braces often being lighter and thinner, and sometimes preferred by patients. Adding finite-element simulation to CAD/CAM may improve the immediate correction and reduce brace weight further. The overall message is that digital manufacture is a valid, and in some respects more convenient, alternative to conventional fabrication, delivering equivalent correction — and, as with all bracing, the outcome still depends most on wearing the brace as prescribed. Because the technology is relatively new, long-term outcome data are still accumulating.

The brace is designed from a 3D scan and manufactured digitally, then fitted and adjusted by a specialist orthotist, with an in-brace X-ray to check the correction. It is worn, reviewed and eventually withdrawn on the same principles as any scoliosis brace, with the spine monitored throughout.

• —A comparison of the clinical effectiveness of spinal orthoses made by conventional manual versus CAD/CAM methods in AIS. (PMID 17108431)
• —Effectiveness of braces designed using CAD/CAM with finite element simulation compared to CAD/CAM only: a randomized controlled trial. (PMID 26861663)
• —Additive manufacturing of spinal braces: evaluation of production process and postural stability in scoliosis. (PMC9502321)
• —Efficacy of CAD/CAM versus CAD and finite element modelling in brace management of idiopathic scoliosis: a narrative review. (PMC8055460)
• —Scoliosis in-brace curve correction and patient preference of CAD/CAM versus plaster moulded TLSOs. (PMID 19308530)