Spinal Disorders D. Pelinkovic, M. D. M&M Orthopaedics 1259 Rickert Drive Naperville, IL 1900 Ogden Ave Aurora, IL Cervical Motion Preservation Neck Pain Symptoms Trapezius myalgia ( Phosphates Bengston 1986) Degenerative changes in facet joints or disc Radiculopathy Loss of disc and foraminal height => nerve compression Hypertrophic facet joints, abnormal motion Inflammatory mediators Nerve is innervated Dorsal root ganglion is sensitive to deformation Myelopathy Mechanical compression of the spinal cord > 40% (Hukuda;JBJS Br 1985;67:609-15) 15) D. Vascular Pelinkovic (Gooding.Jneurosurg;1975;43:9-17) M.D., M&M Ortho, Naperville, IL17) 1
Pathoanatomy Lateral view Sagittal alignm.(normal lordosis 21 ± 13 ) Flex/ Ext views for instability C5/6 most frequent spondylotic -apex of lordosis farthest away from IAR (Friedenberg, Edeiken 1959) C6/7 2nd most common Most common level for post VB osteophytes (Lestini, Weisel 1989) Congenital stenosis Facet arthrosis more common in upper c spine : C3/4, C4/5 Subluxation in upper levels MRI Indications Sx for >2-3 mo, neurologic findings, worsening GAD helpful for tumor, infection, syrinx, demylinating ds Abnormal in 19% 14% < 40y, 28% > 40 y < 40y : > 40y : herniated disc 10% Formaminal stenosis 4% Disc degen or narrowing 25% herniated disc 5% Formaminal stenosis 20% Disc degen or narrowing 60% (Boden 1990. JBJS am 72(8) ) 2
Treatment for Cervical Radiculopathy Surgical indications: persistent radicular pain despite conservative treatment (NSAIDs, PT, epidurals) for 2-3 months or presence of significant numbness or weakness Posterior laminoforaminotomy: - persistent arm pain without significant neck pain - No kyphosis - previous anterior anterior fusion cases, multi-level unilateral radiculopathy, and C7-T1 level in obese pt.) Anterior discectomy and fusion: persistent arm and neck pain (loss of lordosis, significant motor deficits) ACDF 3
Complications associated with ACDF Pseudarthrosis: (must heal/fuse the diskectomy gap) ~3-20% (Phillips et al., Spine 1997); range 0-50% reported Rate is decreased by anterior plating & by use of ICBG 97% fusion for 1-Level ACDF 83% fusion for 2-Level ACDF 27%+ Non-union rate for multi-level level l fusions Plate and/or screw back-out, breakage, failure Slower return to work, driving & activities (healing time) ICBG harvest morbidity (up to 25% complication rate) And, what happens in the adjacent segment? Goal Avoid fusion Preserve segmental motion Pain Function 1 Operation Rationale for Cervical Disk Arthroplasty: High incidence of adjacent-level degeneration & Increased revision i rates seen with ACDF appears to justify development of new technologies to theoretically limit the progression of cervical disk disease. 4
Hx of Artificial Discs Ball bearings in disc Fernström 1950 s Implanted rubber core between flat titanium plates Steffee 1980 s Polyethylene core in two curved plates Brittner-Janz, Marnay Hinged device Kostuik Nucleus replacement using gels with osmotic pressure Ray, Yuan Indications for Cervical Disk Arthroplasty Ideal Cervical disk arthroplasty Candidate: 1- or 2- Level disc herniation with minimal spondylosis Symptoms & signs correlate well with pre-op imaging studies Failed at least 6-12 wks nonop mgmt Spinal cord or root compression documented by MRI and/or CT myelography Mild or no facet arthrosis Pt complaints should be radicular or myelopathy & not axial neck pain Possibly NO! Contraindications for Cervical Disk Arthroplasty Maybe SpineUniverse.com NO! 5
Issues Surrounding Current Indications & Contraindications for CDA One- versus Two-level disk replacement In Europe: (Goffin et al., Spine, 2003) Slightly better outcomes doing 2-level vs 1-level disk replacement But: NO RCT vs Fusion in this setting CDA adjacent to fusion or after previous surgery. Reports of success @ 24 mo f/u (Sekhon. J Spinal Disord Tech, 2005; & Sekhon et al, J Neurosurg Spine, 2005) 24 discs (1-3 level CDAs) in 15 pts 9 prior ACDFs, 15 prior posterior foraminotomies. Significantly decreased VAS scores, no diff in ODI Hypermobility due to aggressive previous facetectomy lead to recurrent neck pain, (but no implant revision reported) Levels adjacent to prior fusion overall, good outcomes thus far Cervical Disk Prostheses currently limited by USFDA to investigational use only Medtronic Medtronic Medtronic Synthes Bryan Cervical Disc System Prestige ST Prestige LP ProDisc-C Cervitech SpinalMotion Stryker Porous Coated Motion Artificial Cervical Disc Kineflex C CerviCore Intervertebral Disc Motion Preservation: it s not just the disc 6
ALL PLL Interspinous ligaments Facet capsule/joint Muscles Clinical Outcomes of CDA Early: uniformly favorable At least as good, if not better, than ACDF (gold standard) BUT, good short & intermediate outcomes may not predict long-term results Mummaneni et al., J Neurosurg Spine 2007: SUMMARY OF DATA PRESTIGE ARTHROPLASTY GROUP was SUPERIOR in: NEUROLOGIC SUCCESS (motor/sensory function) BETTER NECK DISABILITY INDEX SCORES LOWER VAS SCORES FOR NECK PAIN LOWER RATE OF SECONDARY REVISION SURGERIES SF-36 EXCELLENT RESULTS IN BOTH GROUPS RETURN TO WORK 16 d (26.2%) SOONER THAN ACDF Gp RATE OF ADJACENT-SEGMENT REOPERATION SIGNIFICANTLY LOWER IN THE ARTHROPLASTY GP (p<0.05) PRESTIGE MAINTAINED SEGMENTAL SAGITTAL ANGULAR MOTION, AVG > 7º NO CASES OF IMPLANT FAILURE IN PRESTIGE GROUP OVERALL SUCCESS: PRESTIGE WAS SUPERIOR TO FUSION AT EACH POSTOP TIME INTERVAL Prestige ST 7
Cervical Disk Arthroplasty Complications Retropharyngeal hematoma Paravertebral (heterotopic) ossification decreased by NSAID use Bony Ankylosis Subsidence Prosthesis migration intraoperative and delayed Instability/Hypermobility Neurological deterioration, most commonly due to inadequate decompression Visceral injury Segmental kyphosis BRYAN disc-associated (?technical issues on endplt preparation) Prosthesis partial dislocation Severe muscle spasms - excessive distraction? Disphonia and dysphagia Summary High incidence of ASD with ACDF and revision rates for ACDF are higher than for arthroplasty These findings appear to justify the development of motion-sparing technologies to theoretically limit the progression of cervical disc disease Earlier return to work Seven devices are currently undergoing USFDA investigation. Differences in materials, design, and implantation techniques on device performance are unknown. Overall success of human studies are encouraging, with at least equivalent outcomes to ACDF, with advantage of retained motion and, Reported complications are relatively few and manageable and have not resulted in catastrophic neural injury. Longer follow-up is needed to determine whether these devices can function well over time and to determine long-term implant to host and host to implant reactions. 8