Cervical Pseudarthrosis: Diagnosis and Revision Strategies

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1 Cervical Pseudarthrosis: Diagnosis and Revision Strategies William C. Welch, M.D., F.A.C.S., F.I.C.S. Professor of Neurological Surgery Chief, Neurological Surgery, Pennsylvania Hospital University of Pennsylvania School of Medicine Philadelphia, PA

2 Bias/Conflicts Zimmer Spine: unpaid consultant, speaker Synthes consultant (per diem)

3 Introduction Treatment of cervical disorders has evolved from a purely posterior approach to a purely anterior approach to a combination of approaches. In general terms, failed fusion (pseudarthrosis) is associated with pain. Despite our best attempts, cervical pseudarthrosis does occur. Review history, indications, and current thought processes regarding treatment options.

4 History Posterior approach via wide laminectomy advocated for all disorders (akin to lumbar surgery) Cloward, Smith, Robinson all took a Bold Anterior Cervical Approach Studies showed similar results in most instances More recent studies performed to examine outcomes vs. invasiveness

5 Posterior Approach Standard bilateral laminectomy Wide access to posterior and lateral spinal canal Straightforward anatomy Excellent access to exiting nerve root Low risk of vertebral artery injury Potentially destabilizing Potentially higher rates of spinal cord injury

8 Posterior Fusion Techniques Figure of 8 wiring Lateral mass screws Pedicle screws Trans-articular screws Trans-laminar screws Luque rectangle and sublaminar wiring Hooks and rods

9 Posterior Fusion Techniques On-lay bone Local bone Autograft bone High fusion rates Low complication rates

10 Historically, these patients do well clinically and radiographically. What does the treating physician do for persistent symptoms? Is non-fusion (pseudarthrosis) present?

11 Clinical Suspicions Presistent pain New pain Radicular pain Resolution of symptoms then recurrence of symptoms

12 Clinical Suspicions (from Kaiser, CNS) It is recommended that the physician evaluate for the presence of a pseudoarthrosis if the clinical outcome is suspicious for symptomatic fusion failure However strength of association is unknown Quality of evidence: Class III Strength of recommendation: D Recommended that revision of symptomatic pseudoarthrosis be considered since arthrodesis is associated with improved outcome Quality of evidence: Class III Strength of recommendation: D

13 Radiographic diagnosis of pseudarthrosis (from Kaiser, CNS) The absence of motion between spinous processes on dynamic radiographs be used to exclude pseudoarthrosis in lieu of bridging bony trabeculae Quality of evidence: class II Strength of recommendation: B Radiographic assessment by treating surgeon is unreliable and should be performed in a blinded fashion Quality of evidence: class II Strength of recommendation: C

16 Considering Revision? Why was this surgery performed? Why did this failure occur? Does this require revision? What can I do differently? Who/what can help me with this difficult problem?

17 Why was this surgery performed? Myelopathy? Has the patient progressed, improved, plateau? Radiculopathy? Persistent pain or deficit? Neck pain? Was the diagnosis correct?

18 Why did the failure occur? Instability/Mechanical issue? Instrumentation failure (broken screws, rods, plates) Inadequate bone fixation Imperfect placement of instrumentation Host factors (CP, Parkinson s disease) Inadequate instrumentation to overcome host forces (kyphosis) New traumatic event

19 Patient Specific Fusion Risk Factors Osteoporosis Cigarette smoking Metabolic conditions (diabetes, thyroid dysfunction, etc.) Age Body weight Motor neuron dysfunction (cerebral palsy, Parkinson s syndrome, muscular dystrophy) Medications NSAID s SAID s Antimetabolic medications Other risk factors

20 Why did the failure occur? Bone healing deficiency? Mechanisms of Bone Healing Mechanical Factors Matrix factors Local environment Osteoinduction Osteoconduction Cellular factors In growth of cells Activation of growth cascade Expression of growth proteins Generation of electrical potentials

21 What can I do differently? Consider mechanism of failure Should I revise the existing construct? If I attempted an anterior fusion, should I fuse posteriorly? If I attempted a posterior fusion, should I fuse anteriorly? A/P? 540? Correct metabolic issues NSAID Thyroid r/o infection

22 Adjuncts? Instrumentation Generally speaking, stronger is better Generally speaking, more is stronger Anatomic limitations may be present Limitations in surgical experience/comfort levels may be present Bracing More is better Patient limitations Image guidance

24 Adjuncts: Electrical Stimulation Electrical stimulation to promote bone growth has been used for many years in the appendicular skeleton for fracture repair, delayed union, and pseudarthrosis. Electrical bone growth stimulation techniques have demonstrated efficacy in the lumbar spine.. Implanted direct current stimulators Pulsing electromagnetic fields (PEMF) Capacitive coupling

25 Cervical Spine Applications Implanted direct current stimulators generator (anode) preformed wires (cathode) wires placed on bone to be fused size (current density) matters generated current differential for about 6 months no compliance issues stimulator may be removed function can be assessed

26 Occipit-Subaxial Spine

27 Cervical Spinal Applications PEMF stimulators Shen et al (poster, AANS, 2001) 43 patients, multilevel cervical fusions 24 anterior, 9 posterior, 12 combined instrumented fusions, mean follow-up 19 months. PEMF 4 hours/day, 3 months. Radiographic evidence of fusion was demonstrated in 43 of 45 patients (95.6%). 67% (2/3 patients) for occipital-cervical fusion. Now FDA-approved

28 Cervical Spinal Applications Capacitive coupling Induced current through time-varying electrical field specifically configured electrical field small computer-controlled stimulator delivers sinusoidal waveform current through hydrogel surface electrodes wear device 24 hours/day until healing occurs compliance may be less of an issue than PEMF

29 Bone Morphogenetic Proteins Limited publication record for posterior use Published concerns regarding anterior cervical spine use (pre-vertebral swelling)

30 General Recommendations for Posterior Construct/Fusion Failure If failure occurred due to kyphosis, add either/or more posterior instrumentation or anterior support Brace for as long as possible Use electrical stimulation Use iliac crest autograft bone or BMP

37 And Yes, Here it Comes, Wait for it

39 Stabilization/Wolff s Law Astley Coopers Treatise on Dislocations and Fractures of the Joints reported, in 1842, observations which are fully valid even today. On the development of a non-union and of false joints he wrote the following: There is no difficulty, for example, in understanding that the materials effused for the consolidation of a fracture can never be converted into a bony callus, if subjected to frequent motion and disturbance. He recommends the following to the doctor engaged in healing a non-union: to ensure all the mechanical conditions which are essential for the consolidation of callus, comprising perfect rest and immobility, and contact and pressure of the broken surfaces against each other.

40 Anterior Fusion Techniques Cloward, Smith-Robinson, BAK-C cage: 95% fusion rates Addition of instrumentation not proven to increase fusion for single level, does yield benefit in multilevel constructs Autograft bone Allograft bone High fusion rates Low complication rates

46 Why did the failure occur? Poor bone healing? Trauma? Instability/Mechanical issue? Does this require revision? Who can I get to help? ENT Colleague

47 Surgeon Specific Risk Factors Unfamiliarity with procedure Poor establishment of graft-host interface Intraoperative complications Inadequate consideration of biomechanics

48 Must Address Symptoms Addressing neuroforaminal stenosis in the face of radiculopathy while attempting to achieve arthrodesis in revision surgery Maintaining spinal cord/canal integrity Attempting to improve patient s clinical picture, meeting patient expectation, while striving for fusion and maintaining spinal stability and alignment

50 Anterior Revision of Failed ACDF Zdeblick, et al.: 35 patients treated for failed anterior cervical discectomy and arthrodesis. Operative treatment involved repeated anterior Robinson arthrodesis. Their results were reported as excellent for 29 patients, good for one, fair for four, and poor for one. They concluded that, in patients who have persistent symptoms after an anterior cervical arthrodesis, an excellent result can be achieved with repeat anterior decompression and autogenous bone-grafting. Zdeblick TA, Hughes SS, Riew DK, et al. Failed anterior cervical discectomy and arthrodesis. J Bone Joint Surg. 1997; 79-A: Coric et al. utilized anterior revision using allograft interbody fusion material and anterior plating. They reported successful fusion in each of the 19 patients they treated. Based on their findings, they believe anterior revision to be a safe and efficacious procedure. Coric D, Branch CL, Jenkin JD. Revision of anterior cervical pseudarthrosis with anterior allograft fusion and plating. J Neurosurg. 1997; 86:

51 Anterior Revision of Failed ACDF Tribus et al. reported on 16 patients with symptomatic pseudarthrosis treated with revision anterior resection of the pseudarthrosis, decompression, autogenous iliac crest bone grafting, and anterior cervical plating with the titanium locking screw-plate system. They reported that stability was obtained as demonstrated on flexion-extension views in all 16 patients, and 11 patients (75%) rated their pain as improved from prerevision status. They also imparted that they felt anterior revision surgery has several advantages to offer. These include that direct visualization and removal of the pseudarthrosis are both possible, direct decompression of the neural elements is also facilitated. Tribus CB, Corteen DP, Zdeblick TA. The efficacy of anterior cervical plating in the management of symptomatic pseudarthrosis of the cervical spine. Spine. 1999; 24:

52 Posterior Supplementation Brodsky et al: randomized study comparing posterior repair with anterior repair for symptomatic pseudarthrosis. Seventeen patients received anterior repair. 13 (76%) achieved successful fusion and 4 (24%) had persistent pseudarthrosis. Sixteen of 17 patients (94%) that received posterior repair showed radiographic fusion and one patient (6%) continued to have pseudarthrosis. They concluded that posterior cervical fusion proved to be more effective than anterior cervical fusion for repair of symptomatic pseudarthrosis of anterior cervical fusion. Brodsky AE, Khalil MA, Sassard WR, et al. Repair of symptomatic pseudarthrosis of anterior cervical fusion : Posterior versus anterior repair. Spine. 1992; 17: Lowery et al. concluded that the high probability of fusion coupled with good clinical results and few complications support the use of posterior cervical fusion and articular pillar plating for failed anterior cervical fusion Lowery GL, Swank ML, McDonough RF. Surgical revision for failed anterior cervical fusions: Articular pillar plating or anterior revision? Spine. 1995; 20:

53 Posterior Supplementation Phillips et al: Patients that underwent repair for pseudarthrosis. Sixteen patients had a repeat anterior procedure and fusion was successfully achieved in 14 of the patients. Six patients underwent primary posterior repair and successful fusion was judged to have occurred in all patients. Phillips FM, Carlson G, Emery SE, et al. Anterior cervical pseudarthrosis; Natural history and treatment. Spine. 1997; 22: Siambanes et al: 14 patients with pseudarthrosis after anterior cervical discectomy. Posterior stabilization by means of the Roger s wiring technique and radiographic union was achieved in all patients. From their results they support the use of posterior stabilization but advocate an anterior procedure in the face of continued or residual neural compression that is not amenable to a posterior lateral foraminotomy, graft, graft dislodgement, or cervical kyphosis coexisting with nonunion. Siambanes D, Miz GS. Treatment of symptomatic anterior cervical nonunion using the Rogers interspinous wiring technique. J Ortho Am. 1998; 12:

54 Case Study 54 year old woman Good health ACDF (allograft) for radiculopathy Improved then deteriorated Now recurrent arm pain and new neck pain

57 Treatment Myelogram EMG Posterior decompression, extensive foraminotomy, preservation of posterior spinous processes for cable fixation, lateral mass instrumentation, ICAG, EBGS Improvement of arm pain and neck pain Fruitcake at Christmas

59 Conclusions No Best Approach Posterior approach seems reasonable for failed ACDF Well selected and applied instrumentation techniques appear to benefit fusion rates Autograft and BMP seem to provide best radiographic fusion results Adjuncts appropriate in selected cases Best chance of fusion is with initial surgery

61 Go Flyers!

Increased Fusion Rates With Cervical Plating for Two- Level Anterior Cervical Discectomy and Fusion

Increased Fusion Rates With Cervical Plating for Two- Level Anterior Cervical Discectomy and Fusion SPINE Volume 25, Number 1, pp 41 45 2000, Lippincott Williams & Wilkins, Inc. Jeffrey C. Wang, MD, Paul