Anterior Cervical Instrumentation

Youmans chapter 297U. Kumar KakarlaCurtis A. Dickman

Volker K.H. Sonntag

Indication• Absolute indication for cervical plate instrumentaion• Procedures that involve any extent of formal corpectomy• Patients with posttraumatic spinal instability

• Internal fixation and fusion• Restore stability to the structurally compromised spine• Maintain alignment after correction of a deformity• Prevent progression of a deformity• Alleviate pain

Indication• Relative indication for incorporating internal fixation• Malnutrition• Active use of tobacco• Presence of significant osteoporosis or other disorders that result

in poor bone quality• Need for exogenous steroids• History of previously unsuccessful fusion efforts (at the same or

different vertebral levels)

Operative technique• Preoperative Preparation and Positioning• Skin incision• Soft tissue dissection and exposure of the vertebral column• Disectomy with or without corpectomy• Bone graft and plate fixation• Enhancing the natural capacity of bone healing• Iatrogenic impediments to fusion biology• Optimizing the fusion and hardware construct• Closure

Advantage and disadvantage• Advantage• Safe removal of anterior osteophytes• Fusion of disc space affords immobility• Only viable means of directly dealing with centrally herniated disc

• Disadvantage• Immobility at fused level may increase stress on adjacent disc space

Preoperative Preparation and Positioning

• Antiembolic stocking• IV, a-line• Phophylactic ATB• SSEP, MEP• Fiberoptic or awake intubation : traumatic• Methylprednisolone : myelopathy• Graft : allograft, autograft• Fluoroscopy

• confirming the operative level• selecting an appropriately sized cervical plate• directing screw trajectories• assessing final screw positions• evaluating plate alignment

Skin incision

• Right or Left side• Patient’s right hand• Recurrent laryngeal nerve injury , Rt > Lt• Redo operation

• Transverse or longitudinal• Fail to provide sufficient access and visualization• Difficult anatomy, multiple level

Soft tissue dissection and exposure of the vertebral column

• Platysma : split transverse or longitudinal, broad undermining• Sternocleidomastoid m.,tracheoesophageal bundle : avascular plane

and blunt dissect• Trajectory medial to carotid sheath• Palpated vertebral column,osteophyte• Fluoroscopy• ALL, medial insertion of Longus colli m.• Self-retaining : blade under longus colli• Deflate cuffe before insert blade

Soft tissue dissection and exposure of the vertebral column• Injury to the vagal innervation of the larynx• silent aspiration (superior laryngeal branch)• hoarseness (recurrent laryngeal nerve)

• Second retractor to improve Rostral-caudal exposure• High-speed drill to remove obstructing osteophytes• Distraction posts

Disectomy with or without corpectomy

• Superficial diskectomies : straight and angle curets• Corpectomy• Anterior half : bone rongeur• Posterior half : Midas rex drilled

• Microscopy• Epidural space inspect, posterior base of osteophyte• Typical lateral extent of tissue removed for diskectomies or corpectomies spans up to 18 to 20 mm

Disectomy with or without corpectomy

Bone graft and plate fixation

Enhancing the natural capacity of bone healing

• Compressive load(Wolff’s law)• Vertical dimension of the graft material being used is typically sized a few

millimeters longer than the measured diskectomy or corpectomy defect• Adjacent vertebral bodies can be distracted• All soft tissues are removed from the graft material and fusion interfaces• After the posterior half of the graft has been tamped into place, the

vertebral body distraction is released and the remainder of the graft advanced• Palpating posterior to the graft with a nerve hook and visualizing the

posterior border of the graft with fluoroscopy

Iatrogenic impediments to fusion biology

• High-speed drills• Monopolar cauterization• Gelfoam sponge (Upjohn, Kalamazoo, MI.), Avitene powder

(MecChem, Woburn, MA.), Floseal (Baxter, Deerfield, IL.) or bone wax

Optimizing the fusion and hardware construct

• Remove ventral osteophytes : Flush application and midline• Retain cortical bone layer : resist screw to pull out• Graft material is not countersunk away from the ventral margin of the

disk space• Cortical end plates are thinned sufficiently to expose bleeding• Loss of graft height : optimze load-bearing capabilities of these

materials by oscillating saw

Optimizing the fusion and hardware construct

Optimizing the fusion and hardware construct• Selection of screw type and screw length• Variable angle screws

• allows some movement at the screw-plate interface• allows settling of the vertebral body end plate on the interbody graft• load-sharing or dynamic fixation

• Fixed angle screws • do not allow movement at the screw-plate interface• act against settling of the vertebral body end plate on the graft• load-bearing or constrained or static fixation

• combination of fixed and variable angle screws is considered semiconstrained or a hybrid construct

Optimizing the fusion and hardware construct• Degenerative pathology

• hybrid construct using fixed angle screws at the most caudal vertebral level and variable angle screws at the remaining levels

• Traumatic pathology• constrained system and thus use fixed angle screws at all levels and aim for bicortical purchase

• Two-finger tightness• Screw trajectory : capture the denser bone tissue in the subchondral region of the

vertebral body• Don’t crossing distal vertebral endplate• When fixation involves multiple segments, the plate should be secured at as many

points as possible

Closure

• Assessing the alignment of the vertebral column after fixation, the position of the graft with respect to the epidural space, and the length of the plate and position of the screws with respect to the rostral and caudal disk spaces• Fluoroscopy• Bacitracin-containing saline is used to irrigate the wound• Hemostasis• Remova retractor and confirm carotid pulse• Surgical drain• Close platysma m. and dermis• Skin : running subcuticular suture and Steri-Strips

Orthoses

• Three-column traumatic disruption of their spinal column or who suffer from an underlying metabolic impediment to healing (i.e., rheumatoid arthritis) : a halo brace, or a posterior fusion • Procedure involves three or more corpectomies : halo brace or

augmented with a posterior fusion• When screw purchase is good in patients undergoing a single-level,

two-level, or three-level fusion and plating procedure for spondylotic disease : maintained without a collar after surgery

Post operative follow-up• Baseline radiographic (fluoroscopic or plain film) documentation of

the fusion and instrumentation construct is obtained at the completion of the surgical procedure• Repeat plain film at 4-6 wks• Include dynamic view if there is evidence of graft incorporation and

stable hardware position• When evidence of a fusion response (bridging trabeculated bone

across the graft-vertebral interface) is obtained, patients are instructed in neck-strengthening exercises

Post operative follow-up• Dynamic views are obtained 6 to 8 weeks after surgery in patients

managed in a halo brace with the halo ring disconnected from the vest but still attached to their skull• The halo ring is removed only after stability is demonstrated

Post-op checks• Airway obstruction : post-op wound hematoma• Weakness of nerve root at level operated• Long tract sign : cord compression• Hoarseness : vocal cord paralysis

Complication• Exposure injury• Perforate of viscus : pharynx, esophagus• Vocal cord paresis : injury recurrent laryngeal nerve• Vertebral a injury : thrombosis or laceration• Carotid injury : thrombosis, occlusion, laceration• CSF fistula• Horner’s syndrome : sympathetic plexus lie within longus colli m.• Thoracic duct injury• Thrombosis of IJV

Complication• Spinal cord or nerve root injury

• Spinal cord injury• Avoid hyperextension during intubation• Bone graft must be shorter than interspace depth• Sleep induced apnea

• Bone fusion problem• Failure of fusion• Anterior angulation deformity• Graft extrusion• Donor site complication

Casper plate Synthes plate Orion plate

Codman plateAtlantis plate

Atlantis vision system

ABC system

Atlantis Translational system

UNIPLATE System