Alecta Cervical Disc Prosthesis

Cervical Disc Prosthesis

Alecta Cervical Disc Prosthesis is used for preserving the mobility after a discectomy and it allows for any type of movement in the range of motion including flexion, extension, and rotation. Disc Prosthesis is manufactured from titanium material which is compatible with MRI and CT to be suitable for the use during an anterior Smith – Robinson approach. It has a serrated structure, which allows for gripping to superior and inferior surfaces. Thus; the prosthesis, made only of titanium alloy, can be placed tightly to the superior and inferior parts.

Internal surfaces of the prosthesis are coated with a special alloy to reduce corrosion and fracture coefficient of the prosthesis. Thus, the sustainable motion of the implant is maintained. Placing and fixing procedures can be performed by using the “Alecta Prosthesis Holder” as the only hand-held tool. The prosthesis design allows for ±8° flexion / extension, a ±8° lateral curve, and ±5° rotation. Various lengths are available allowing for the application to a variety of different anatomical structures.

The physical construct of the product comprises an upper and lower segments made of “Titanium Ti6Al4V-ELI Grade 5” material. The part in the lower segment coated by Titanium Nitride alloy is the main part responsible for the maintenance of motion.

A single implant holder (Alecta Prosthesis Holder) is compatible with all implant sizes. To obtain an optimal and controlled positioning of the prosthesis, the implant should have been attached to the hand-held tool correctly.

Surgical Technique

1- Discectomy

• Start releasing from the anterior part of the disc as far as the uncus allows.
• Exercise care to remove osteophytes.
• Perform discectomy on the disc surface by watching connective tissue behind.
• It is important to place the osteophytes onto the superior and inferior endplates.

2-Placing the Caspar Distractor

• The second Caspar probe is directed from the superior endplate to inside of the inferior vertebra.
• To achieve a parallel distraction, probes should be aligned parallel to one another and to the endplates.

Note: When it is a two-step procedure, the Caspar pin can be placed at the half of the height of the vertebral body.

3-Distraction

• A distraction clamp is inserted into the disc space and advanced further with the first distraction.
• The Caspar distractor is placed and tightened until the aimed distraction is achieved.
• Place the distraction clamp from the posterior to inside as much as it is possible. Aim an advanced and parallel distraction. It is recommended that distraction clamps should be lateralized consecutively one after the other in order to optimize distraction.
• Firstly, the desired level of distraction is achieved. The Caspar distractor is locked to maintain the distraction.
• After the procedure, the distraction clamp is removed.

4-Trial Implants

• Measurements of the depth and width are beneficial to determine the trial size. Trials will allow for determining the height of the last implant, too. Each size was colour-coded.
• The available sizes are as follows: 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, and 9.5 mm. The trial should be performed by trying a height not higher than the height of healthy adjacent discs.
• The trial implant is screwed on the conveyor and placed in the discal space under fluoroscopy guidance.
• The Caspar distractor is placed and, when it is tightened, the trial implant is placed to confirm the correct selection of the height and width.
• The correctness of the height is determined as follows: The inserted prosthesis should not exceed the height of healthy adjacent discs and should remain stable in the intervertebral space without causing an excessive distance between the respective vertebrae.
• Foramina in the trial implant allow for controlling the anterior-posterior position.
• Release the Caspar distractor to remove the trial implant.

5-Attaching the Prosthesis to the Hand-Held Tool

The prosthesis is placed by means of an implant holder.

• The implant conveyor should be on the same axis with the disc. The Caspar distractor should maintain the intervertebral distraction.
• Positioning can be confirmed by visual inspection.
• During the rotation, the correctness of the position of the implant conveyor is checked.
• The placement of the prosthesis in the disc space under fluoroscopy guidance is performed by advancing the implant holder while tapping its clamping knob with a hammer slightly.

Note: Exercise care to keep the prosthesis central to the vertebral endplates.

• The fluoroscopic guidance allows for confirming the correct positioning of the prosthesis.
• The Caspar conveyor is advanced in parallel to be attached to the vertebral endplate.
• After confirming the correct positioning of the prosthesis and concluding the tightening of the implant conveyor, the implant is inserted and the hand-held tool is withdrawn carefully.
• On the vertebral endplate, the implant is under compression by the Caspar distractor.
• Firstly, the compression is released and the Caspar distractor is disassembled.