Cervical disc arthroplasty

Bioengineering Studies 12.4 Cervical Disc Arthroplasty Remain... 

Thirdly, the surgical access to the anterior cervical spine is easier, and less risky for the patient, than the access to the anterior lumbar spine. Furthermore, the ease of access for cervical disc replacements is preserved during revision, whereas in the lumbar spine, scar tissue and adherent vessels greatly complicate the anterior revision process. For these main reasons, cervical disc arthroplasty appears to be a less risky proposition than lumbar arthroplasty, both in terms of the feasibility of available technology options for the implants, as well as in terms of the risk to the patient during the procedure. 

DLAngelo DJ, Foley KT, Morrow BR, Schwab JS, Song J, German JW, et al. In vitro biomechanics of cervical disc arthroplasty with the ProDisc-C total disc implant. Neurosurg Focus 2004 September 15 17(3) E7. 

In several key aspects, total disc arthroplasty is a more attractive technology for the cervical spine than for the lumbar spine. First of all, the biomechanical demands on a cervical prosthesis, which must support the weight of the head and the neck above it, are about an order of magnitude less stringent than in the lumbar region, which instead must support the weight of the entire upper torso. The lower loads of the cervical spine also permit a much... 

Secondly, the indications for cervical disc replacement, which include myelopathy and radiculopathy, are broader and more prevalent than for lumbar disc replacement [53]. That is, more patients undergoing cervical fusions today may be candidates for disc arthroplasty, provided certain other contraindications are not met, such as nonintact posterior elements and osteoporosis. In contrast, the list of contraindications in lumbar disc replacement is currently so extensive that it effectively precludes the vast majority of lumbar fusion candidates from receiving an arthroplasty [54]. 

In vitro biomechanical testing of the ProDisc-C was performed by DiAngelo et al. [59]. Six cervical spines (C2-C7) were tested sequentially in the intact state, following disc arthroplasty, and then after a simulated single-level fusion. The testing frame was a custom-built load frame attached to a servo-motor load acmator (International Device Corp., Novato, California, USA) with a robotic controller (Adept, Inc., San Jose, CaUfomia, USA), in line with a load cell. Custom fixtures were then used to drive the cervical spine in displacement control to... 

Total disc replacement is a new, promising field of spine implant technology that has the potential to revolutionize the treatment of degenerative disc disease. Today, conventional UHMWPE is incorporated in both cervical and lumbar disc arthroplasty. It is clear from both in vitro and clinical data that disc replacements can successfully preserve the motion of treated spinal level. Aside from patient satisfaction and the speed of recovery, there are modest clinical benefits with disc replacement that manifest in the short term as compared with fusion. Furthermore, unlike fusion procedures, disc replacements may also need to be revised due to poor implantation technique or failure of the device. On the other hand, over the long term, the primary benefit of disc replacement is expected to be the reduced incidence of adjacent segment degeneration, which will hopefully offset the new, and as yet, poorly quantified risks associated with the technology. It will be many years, probably over a decade, before sufficient... 

Dmitriev AE, Cunningham BW, Hu N, Sell G, Vigna F, McAfee PC. Adjacent level intradiscal pressure and segmental kinematics following a cervical total disc arthroplasty an in vitro human cadaveric model. Spine 2005 May 15 30(10) 1165—72. 

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