Patient-specific spinal rods

Most everything about you is unique. From the color of your eyes to your finger prints, no two humans are completely identical. Capitalizing on this in the medical industry is paramount, especially for spinal surgeons.

Historically, when a patient’s spine deteriorates, surgeons screw long metal rods along the spine. During surgery, the surgeon then uses a bending tool to curve the screws to adhere to the spine’s shape. These benders can create indentations or notches in the rod – weak points that can fail, often requiring two or more surgeons to operate, providing room for error and variability.

“In recent years, the spinal community has seen a growing body of clinical evidence demonstrating that the leading indicator of patient outcome is the postoperative alignment of the spine, and the optimal alignment is specific to each patient. Getting the patient’s unique alignment correct is critical to the success of the operation,” says Jamie Page, global brand manager for French medical device manufacturer Medicrea.

As a result, Medicrea created the the UNiD rod. Customized for each patient, each UNiD rod is pre-contoured using a controllable and reproducible industrial process, eliminating the intraoperative use of a bending device.

UNiD line

The company first introduced the UNiD thoracolumbar rod, and more recently, the technology has been extended to the cervical spine with the UNiD cervical rod. In parallel to the UNiD rod, Medicrea has initiated development of a range of UNiD intervertebral devices with the first 3D-printed, patient-specific spinal device successfully implanted in France. Ongoing development efforts have led the company to bring 3D-printing machinery and expertise in-house, to advance UNiD technology by creating patient-specific morphological implants in shapes and structures not available via traditional manufacturing methods.

“The impact of hardware on spinal alignment has always been a part of the company’s development ethos. UNiD rods are systematically used in conjunction with traditional posterior fixation,” Page says. “The rods connect the standard implants used to anchor the construct and provide stabilization while the vertebrae fuse together. PolyAxial Spine System (PASS) posterior fixation technology was developed by Medicrea to achieve this result in a new, gentle, and effective way.”

The PASS platform has extended in the same way as the UNiD rod development – PASS LP for thoracolumbar fixation and PASS OCT for cervical. Using PASS + UNiD in combination provides an effective alignment solution, minimizing forces applied on the spine when securing the rod.

Patient-specific

UNiD technology is customized to each individual’s anatomy using proprietary software. Medicrea’s UNiD lab team of biomechanical engineers take measurements from images of the patient’s spine, and surgeons use that data for operation planning, calculating the final shape of the implant using advanced spinal alignment algorithms. Surgeon expertise, clinical evidence, and proprietary software create the optimal implant for the patient.

“Following surgical intervention in the occipito-cervical spine, the shape of the rod directly impacts the fixed position of the head and neck and dramatically changes how the patient looks and feels,” Page says. “The UNiD rod must be compatible with the fixation system used in diameter and length – a challenge greatly increased for rods with two diameters, which are frequently used in this type of surgery.”

There is no manual bending tool in existence which can accommodate the transitional point between diameters. The UNiD cervical rod technology removes this existing surgical barrier by creating identical single or dual- diameter rods, manufactured specifically for the patient and delivered directly to the operating room.

“We have the option to manufacture our patient-specific implants in both titanium alloy (Ti6Al4V) and cobalt chrome. Both materials are widely used in spinal fusions with excellent results. Surgeons will choose both the material and the diameter of the implant based on their technique,” Page says.

Surgeon input

“The manufacturing process begins and ends with surgeon collaboration, fully supported by our UNiD lab. Once the design has been finalized, the patient-specific rod itself is customized using an industrial contouring process that allows us to bend the implant without creating any weak points in the material,” Page explains. “After shaping the rod to millimeter precision, an identification code is laser-etched onto the implant before the final cleaning and quality control process. Lastly, the implant is sterilized prior to delivery in the operating room.”

While the algorithms and parameters used to calculate the optimal implant shape remain the same, the outcome is different every time because the data used is specific to the individual patient. Additionally, the surgeon can apply different strategies to achieve the same end result, making collaboration a critical part of the process.

“Medicrea has always maintained a close dialogue with surgeons to bring new solutions to the table. In this case, the need was obvious. Surgeons were already customizing their rods, but it happened during the operation using very basic bending tools which resulted in approximation in shape, loss of critical operating time, and even material damage. Essentially, surgeons were left to perform the last step in the implant manufacturing process without any support from the actual device manufacturer,” Page says.

“What we have learned so far in pioneering a personalized spine has convinced us that strategic surgical planning and analysis are key elements of a successful spinal surgery. Each time we collaborate with a surgeon, which is more than 800 times now, we are also benefiting by building a larger and larger data set that can be used to define the optimum strategy for the next individual patient. We are building something that is ultimately much larger than a patient-specific implant. Our work stands to benefit the health system as a whole.”

Medicrea USA Corp.

www.medicrea.com

About the author: Arielle Campanalie, associate editor for Today’s Medical Developments, can be reached at acampanalie@gie.net or 216.393.0240.