The first anterior cervical fusion surgeries were performed in the early 1950s by Bailey and Badgley. At that time, many others such as Cloward, Smith, and Robinson contributed greatly to the refinement of cervical fusion techniques. The high rates of nonunion and kyphosis rates in multi-level cases led to the design and development of another type of anterior internal cervical fixation device.
The first plate was developed by Bohler in 1964, which was the basis for the many plates available today. Since then, the Anterior Cervical plates have evolved and improved fusion rates. Fusion has been shown to contribute to the earlier mobilization of the patient, less need for cervical collars postoperatively, greater loading force applied to the graft, lower incidence of graft detachment, and better ability to repair deformities. of the spine.
In 1970 Orozco and Llovet were the first to report their use of a plate produced by the ASIF. These authors used H-shaped ASIF plates, which were the predecessors of the current plate made by Synthes Spine. In the early 1980s, Caspar popularized anterior cervical plating in collaboration with Aesculap. Orozco and Caspar`s plates were both unrestricted backout plates. In this construct, the screw angulation was determined by the patients’ needs and the surgeon’s preference. These constructs did not have a fixed-moment arm and had limited fixation at the screw–plate interface. This led to greater exposure of the graft to compressive forces, allowing for a higher chance of fusion. The unrestricted backout plates had several disadvantages such as the demand for a bicortical screw purchase, which was technically demanding. Overpenetration could result in spinal cord injury, and under-penetration could result in construct failure and screw pullout. Furthermore, the cumbersome and difficult task of fluoroscopy was necessary to visualize the lower cervical regions. The Orozco and Caspar plates were nonrigid meaning that the motion was allowed at the plate–screw interface.
At the same time the Caspar plate was being developed, Raveh produced a titanium-coated hollow-screw reconstruction plate at the University of Berne. By inserting an expansion bolt into the lath, the screw was rigidly affixed to the plate, avoiding the need for a bicortical purchase.
How and when was the CSLP born?
In Switzerland, Morscher modified the Orozco plate for use with monocortical, locking screws; this was reported in 1986. The system was introduced in the US in 1991 by Synthes.
What were its advantages?
- The Synthes CSLP did not require a bicortical purchase because a titanium expansion screw was used to affix the screw rigidly to the plate. The advantage of the monocortical screw purchase was that intraoperative fluoroscopy was not necessary and, thus, operative time was reduced. In addition, the locking screw helped prevent screw backout.
- Another difference between the Caspar plate and the Synthes plate was that there was a fixed angle of entry for the screw and plate in the latter. The Synthes screw lengths were available in a limited range.
- Load Sharing: Carefully designed
- Follows ‘Wolff’s Law’ to allow plate stiffness (load transmission through graft).
- Stable Fixation: Screws lock to the plate
- Stabilizes the motion segment:
- Stabilizes the motion segment the plate and minimizes motion between graft and vertebrae.
- Buttresses the graft against excessive compressive loads thereby minimizing subsidence, maintaining lordosis, disc height, and nerve root decompression.
How did this system evolve?
During its lifetime, several new generations of CSLP were developed:
• Adjusting the hole pattern to multilevel discectomies;
• Decreasing the plate size to conform to small-statured spines;
• And now–offering variable angle and self-drilling screws to ease the technique.
Documentation:
- CSLP-SGT.Depuy-Synthes.pdf
- CSLP-Brochure.(Synthes version).Depuy-Synthes.pdf
- CSLP-VA-SGT.(Synthes version).Depuy-Synthes.pdf
- CSLP-SGT.(Synthes version).Depuy-Synthes.pdf
What do you think about this system? Your comments are welcome!
References: Anterior cervical plates: a historical perspective.ROHAM MOFTAKHAR, M.D., AND GREGORY R. TROST, M.D. Department of Neurosurgery, University of Wisconsin School of Medicine, Madison, Wisconsin