Degenerative disc disease
Degeneration of one or several lumbar disc leads to the failure of the intervertebral disc to achieve its main functions: shock absorption and stability.
This can be responsible for low back pain.
Several grades of degeneration are described. The Pfirmann classification is most commonly used.
Sometimes, inflammation may also be present around the degenerative disc. It is referred to as a Modic I sign.
When the medical treatment with painkillers, rehabilitation, and infiltrations fails to provide effective pain control, the surgical treatment can be discussed.
The surgical treatment consist of performing a spinal fusion at the index level or performing an arthroplasty (motion preservation device).
Lumbar disc replacement
The lumbar artificial disc replacement, aka disc arthroplasty, preserves the mobility between two vertebra, unlike a fusion.
The prosthesis is an implant that is inserted in between two vertebra, filling in for the degenerative disc that is removed. Lumbar disc replacement are done through an anterior lumbar approach.
Careful preparation of the vertebral endplates, and posterior release of the longitudinal ligaments are done before the implant is inserted.
Several types of prosthesis are available and used:
- Mechanical disc prosthesis (Mobidisc, Prodisc): two metallic endplates with a polyethylene space in between.
- Viscoelastic disc prosthesis (ESP): two metallic endplates bound together by a viso elastic structure, offering a vertical load absorption capacity, like a cushion.
Preserving motion at the operated level, reduces stress on adjacent discs, thus reducing the risk of adjacent disc degeneration.
Total disc replacement must not be performed when the facet joints are degenerative. Mobility on arthritic joints would lead to pain.
Fusion through anterior approach (ALIF: Anterior lumbar interbody fusion)
Arthrodesis is the fusion between two or more vertebra.
When performed through an anterior approach, the intervertebral disc is removed from the front.
Careful preparation of the vertebral endplates, and posterior release of the longitudinal ligaments are done before the implant is inserted.
An intervertebral device called a “cage” is placed between the two vertebra along with a bone graft.
The anterior approach spares the posterior spinal muscles, allows for a greater bone graft, and a better height and lordosis restauration.
Preoperative
Postoperative
Hybrid surgery
Hybrid surgery is the combination of a spinal fusion and an artificial disc replacement.
When facet joints are too arthritics, arthroplasty cannot be performed, and a spinal fusion is rather done.
However, when several degenerative disc are treated, some levels may benefit from an artificial disc replacement, while some require a fusion.
The procedure is usually done through an anterior retroperitoneal approach.
Degenerative discs are carefuly removed and replaced by either a disc prothesis or by an ALIF (Anterior Lumbar Interbody Fusion) cage.
Fusion through posterior approach (TLIF: Transforaminal Lumbar Interbody Fusion)
Arthrodesis is the fusion between two or more vertebra.
Through a posterior approach:
- Instrumentation is performed with pedicular screws, linked by a rod.
- Nerve roots and dural sac are released accordingly.
- An intervertebral cage, and bone graft may be inserted through the posterior part of the disc.
- Posterior elements are prepared with chisels, and bone graft is applied.
Fusion through lateral approach (OLIF: Oblique Lumbar Interbody Fusion)
Arthrodesis is the fusion between two or more vertebra.
When performed through a lateral approach, the intervertebral disc is removed from the side.
An intervertebral body device called a “cage” is placed between the two vertebra along with a bone graft.
The lateral allows for a greater bone graft, and spares the posterior spinal muscles.
