3D printed orthopaedic implants

Allegra Orthopaedics (AMT, 18.5 cents)
Market capitalisation: $19 million
Three-year total return: +7.2% a year
Analysts’ consensus target price: n/a

Since 2014, orthopaedic manufacturer Allegra Orthopaedics has held an exclusive global licence to the composite bio-compatible and bio-degradable ceramic “synthetic bone” material Sr-HT-gahnite, developed at the University of Sydney: the lead product is a 3D-printed spinal cage, which works to regenerate bone under spinal load conditions, and is completely resorbed by the body.

But in July, Allegra bought the patents to Sr-HT-gahnite for 4.8 million shares.

Sr-HT-gahnite is composed of strontium, hardystonite (a calcium-zinc- silicate) and gahnite, a zinc-aluminium-oxide. The material can simulate the performance of natural bone by balancing mechanical strength with the bioactivity for bone regeneration.

The first product Allegra plans to commercialise is an inter-body cervical spinal cage, to be used in spinal fusion surgery to treat neck or lower back pain. Inter-body cages are placed between the bodies of two adjacent vertebrae, after removing the inter-vertebral disc that typically occupies this space. Spinal cages may be made of metal, polymer, ceramic, or a fusion of different materials, but Allegra says Sr-HT-gahnite can potentially be the world’s first fully synthetic spinal cage that can regenerate bone under spinal load conditions, but be completely absorbed, leaving the body free of foreign materials. Importantly, the material can be 3D-printed.

The company also plans to use the synthetic material in bone cavity filler granules, to help resolve bone infections, and for the use in orthopaedic, trauma, and spinal surgery, and in anterior cruciate ligament (ACL) screws, but the spinal cage program is the most advanced, and is currently in a pre-clinical large animal study, in sheep (results in sheep are considered closely translatable to the human spine.)

This study, which is being done in France, has been delayed because of travel restrictions and the ongoing COVID-19 situation: the pilot study yielded positive results, but there have been fractures of the implants during the six-month study. As the design of the device was based on forces in the human spine, it is not too worrying that the main cause of the fractures is associated with the animal model – however, Allegra is using the time provided by this delay as an opportunity to use recent advancements in 3D printing technology to enhance the implant design, and improve the material, in order to progress the device approval. The revised design is expected improve the strength of the implant significantly and allow for the physiological differences in the animal mode. This has delayed the pathway of application to the FDA and the TGA.

Based on the positive early results of the Sr-HT gahnite granule project for bone cavity filler, Allegra plans to submit to the FDA in 2021. The ACL screw project is expected to have a final design by the end of 2020.

Allegra is also working on using Sr-HT-gahnite to secure tendons from kangaroos to help the orthopaedic reconstruction of human ligament injuries. In 2020, Allegra also began making face shields for frontline health workers, to help protect them from Covid-19 infection.

Allegra also has an orthopaedics division that distributes a range of orthopaedic implant products and surgical instrumentation from Australian and international suppliers, covering all specialities from foot, ankle, primary knee to complex lower limb arthroplasty and tumour solutions. Sales revenue of this division grew by 25% in FY20, to just over $5 million, helped by the introduction of personal protection equipment (PPE) to the product portfolio, while its operating profit rose more than three-fold.

James Dunn

James is an experienced senior journalist and host of The Inside Network's industry events.