Anterior cervical discectomy and fusion

Original Editors - Stacy Callow

Top Contributors - Stacy Callow and Elodie Baele - Elodie Baele



Definition/Description


Anterior cervical discectomy and fusion (ACDF) is one of the most common surgical procedures performed by neurological and spinal orthopedic surgeons. Most common cause for this operation is a ruptured cervical intervertebral disk. Another reason for surgery are spurs that irritate a nerve root19. With the operation, specialists can remove these spurs. Discectomy is done to give more space for the blocked nerve (=decompression) and the fusion is necessary to stabilize the cervical segment.


Clinically Relevant Anatomy


[3] The cervical spine consists of 7 vertebrae, numbered C1-C7. The two upper vertebrae have a unique shape. The atlas (C1) supports the head and gives the possibility to move the head forward and backward (such as nod “YES”). The axis (C2) gives the head the possibility to move the head laterally (such as shake “NO”). The five remaining vertebrae have a bearing function. The main functions of the cervical spine are to support the head and allow the motility of the head and the most important muscles in this region are 1) M. Sternohyoideus 2) M. Omohyoideus 3) M. Sternothyroideus 4) M. Sternohyoideus 5) M. Sternocleidomastoideus 6) M. Stylohyoideus3 .


Indications for procedure


• Diagnostic tests (MRI, CT, myelogram) that show a herniated or degenerative disc in the cervical region • Degenerative conditions, including disc herniation’s and spinal stenosis8 • Significant weakness in your hand or arm • Arm pain worse than neck pain • If physical therapy or medications fail to relieve your neck or arm pain caused by pressure on the spinal nerves • Cervical spondylotic myelopathy13

Characteristics/Clinical Presentation



Outcome measures


Treatment effectiveness following spine surgery is usually measured with the help of patient-reported outcome (PRO) questionnaires. Better measuring instruments specific to ACDF are patient-reported outcome questionnaires (VAS-neck pain [NP], VAS-arm pain [AP], NDI, SF-12 and EQ-5D.) We can also use established calculation methods to calculate anchor-based MCID values using the North American Spine Society (NASS) patient satisfaction scale as the anchor: 1) average change, 2) minimum dectable change (MDC), 3) change difference, and 4) receiver operating characteristic (ROC) curve analysis. Here reflect minimum clinically important differences (MCID) clinically meaningful improvements to patients6. SF-36 PCS was the most representative PRO measure. MDC appears to be the most appropriate MCID method 7.

Medical management


The incision is made in the front of the spine through the throat area. After the disc is removed, a bone graft is inserted to fuse together the bones above and below the disc space. Discectomy literally means "cutting out the disc." A discectomy can be performed anywhere along the spine from the neck (cervical) to the low back (lumbar). The surgeon reaches the damaged disc from the front (anterior) of the spine through the throat area. By moving aside the neck muscles, trachea, and esophagus, the disc and bony vertebrae are exposed. Surgery from the front of the neck is more accessible than from the back (posterior) because the disc can be reached without disturbing the spinal cord, spinal nerves, and the strong neck muscles. Depending on your particular symptoms, one disc (single-level) or more (multi-level) may be removed. After the disc is removed, the space between the bony vertebrae is empty. To prevent the vertebrae from collapsing and rubbing together, a spacer bone graft is inserted to fill the open disc space. The graft serves as a bridge between the two vertebrae to create a spinal fusion. The bone graft and vertebrae are fixed in place with metal plates and screws. Following surgery the body begins its natural healing process and new bone cells grow around the graft. After 3 to 6 months, the bone graft should join the two vertebrae and form one solid piece of bone. The instrumentation and fusion work together, similar to reinforced concrete.19,10

Complications


Each surgery has risks; the possible complications of ACDF will depend on the ability of the surgeon and the patient’s personal risk factors, such as: smoking, physical condition, diabetes, condition of the affected disc, bone strength, etc… 10,4 The possible complications are: - Development of isolated postoperative dysphagia - Postoperative hematoma - Symptomatic recurrent laryngeal nerve palsy - Inadequate symptom relief after surgery - Infection - Vertebral artery injury9 during elective anterior cervical discectomy and fusion from C3 to 7 - Internal jugular venous thrombosis11 - Hoarseness

With regard to the postoperative pysphagia, a LEO approach (lateral surgical dissection to the omohyoid muscle) should be selected if the level of surgery involves C3-C4. If the vertebrae’s C6-C7 are damaged, it is probably better to use a left-sided MEO approach (medial surgical dissection to the omohyoid muscle)5.

After fusion, you may notice some range of motion loss, but this varies according to neck mobility before surgery and the number of levels fused. If only one level is fused, you may have similar or even better range of motion than before surgery. If more than two levels are fused, you may notice limits in turning your head and looking up and down20.



Physical Therapy Management


POST-OPERATIVE Each physician has his/her own specific guidelines for the rehabilitation process. Therefore protocols are used. Deviations from the protocol are dependent on prior level of function, general health of the patient, equipment available, patient goals, specific orders written on the prescription, and others. It is the treating therapist’s responsibility along with the referring physician’s guidance to determine the actual progression of the patient within the protocol guidelines. Three important components of the therapy are scapular stability, cervical stability, and functional activity. [1] [2]

It is important that the patient follow the limitations set forth from the physician during the first two weeks and then a gradual progression toward functional activities that do not place excessive stress to the cervical region.16 The therapy consists of:

• Facilitating cervical ROM within a pain free range. • Treatment of Hyperactivity of the upper traps along with an imbalance of decreased lower

          trap strength. 

• Exercises to increase scapular and cervical stability within a safe limit. • Pain relief • Patient education (pacing, healing time, ergonomic advice)17 Once proper stabilization can be demonstrated by the patient without cueing, a progression of exercises to further develop and improve stabilization (coordination) should be considered.16


Prognosis


Most studies conclude an improvement in neck pain, arm pain and range of motion. If we compare to other treatments such as cervical arthroplasty, we can say that patients who received Mobi-C TDR device for treatment of 2-level symptomatic degenerative disc disease experienced significantly greater improvement than ACDF patients in NDI score at every time point and significantly greater improvement in VAS neck pain score at 6 weeks, and at 3,6n and 12 months postoperatively. The reoperation rate was significantly higher in the ACDF group at 11.4% compared with 3.1% for the TDR group12. When we look to a surgical treatment for single-level cervical symptomatic degenerative disc disease, we can conclude that after 5 years, ProDisc-C patients had statistically significantly less neck pain intensity and frequency14. A comparison between a cervical disc arthroplasty with anterior cervical discectomy and fusion for the treatment of cervical spondylotic myelopathy works to the advantage the arthroplasty where there was a lower incidence of complications13. It is better to choose a Zero-Profile implant in an anterior cervical discectomy and fusion. In the early follow-up the incidence of dysphagia was lower compared with that in the cage with plate and the symptom duration was much shorter15.

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[1] Arts M.P. et al., ‘The Netherlands Cervical Kinematics (NECK) Trial. Cost-effectiveness of anterior cervical discectomy with or without interbody fusion and arthroplasty in the treatment of cervical disc herniation; a double-blind randomized multicenter study.’ BMC Musculoskeletal Disorders. 2010, 11:122. (level of evidence: 1B) [2] Peter F., ‘ACDF: Anterior Cervical Discectomy and Fusion.’ 2011 (level of evidence: 5) [3] Michael Schunke, Erik Schulte, Udo Schumacher, Markus Voll, Karl Wesker, Prometheus, Atlas of Anatomy [4] Fountas, K.N. et al. Anterior cervical discectomy and fusion associated complications. Spine. 2007: 32(31): 2310-7. (level of evidence: 2A) [5] Fengbin Y et al., ‘Dysphagia after anterior cervical discectomy and fusion: a prospective study comparing two anterior surgical approaches.’ Eur Spine J. 2013 May;22(5):1147-51. (level of evidence: 1B) [6] Parker SL et al., ‘Assessment of the minimum clinically important difference in pain, disability, and quality of life after anterior cervical discectomy and fusion: clinical article.’ J Neurosurg Spine 2013 Feb;18(2):154-60. (level of evidence: 2B ) [7] Auffinger BM et al., ‘Measuring surgical outcomes in cervical spondylotic myelopathy patients undergoing anterior cervical discectomy and fusion: assessment of minimum clinically important difference.’ PLoS One. 2013 Jun 24;8(6):e67408 (level of evidence: 3B) [8] Goldberg EJ et al., ‘Comparing outcomes of anterior cervical discectomy and fusion in workman’s versus non-workman’s compensation population.’ Spine J. 2002 Nov-Dec;2(6):408-14. (level of evidence: 2B) [9] Gantwerker BR et al., ‘Vertebral artery injury during cervical discectomy and fusion in a patient with bilateral anomalous arteries in the disc space: case report.’ Neurosurgery. 2010 Sep;67(3):E874-5. (level of evidence: 3B) [10] Grigory Goldberg et al. ‘Anterior Cervical discectomy and fusion.’ Operative techniques in Orthopaedics, Volume 13, Issue 3, 2003 July, pages 188-194. (level of evidence: 3A) [11] Karim A et al., ‘Internal jugular venous thrombosis as a complication after an elective anterior cervical discectomy: case report.’ Neurochirurgy 2006 Sep;59(3):E705. (level of evidence: 3B) [12] Davis RJ et al., ‘Cervical total disc replacement with the Mobi-C cervical artificial disc compared with anterior discectomy and fusion for treatment of 2-level symptomatic degenerative disc disease: a prospective, randomized, controlled multicenter clinical trial: clinical article.’ J Neurosurg Spine. 2013 Nov;19(5):532-45. (level of evidence: 1B) [13] Ding C et al., ‘Comparison of cervical disc arthroplasty with anterior cervical discectomy and fusion for the treatment of cervical spondylotic myelopathy.’ Acta Orthop Belg. 2013 Jun;79(3):338-46. (level of evidence: 2B) [14] Zigler JE et al., ‘ProDisc-C and anterior cervical discectomy and fusion as surgical treatment for single-level cervical symptomatic degenerative disc disease: five-year results of a Food and Drug Administration study.’ Spine (Phila Pa 1976) 2013 Feb 1;38(3):203-9. (level of evidence: 1B) [15] Miao J et al., ‘Early follow-up outcomes of a new zero-profile implant used in anterior cervical discectomy and fusion.’ J Spinal Disord Tech. 2013 Jul;26(5):E193-7. (level of evidence: 1B) [16] Issada Thongtrangan, MD, rehabilitation department, Cervical Fusion Protocol (level of evidence: 5) [17] RNOH; physiotherapy April 2012. Review date 2014, In association with the UCL Institute of Orthopaedics and Musculoskeletal Science, Rehabilitation guidelines for patients undergoing spinal surgery. (Level of evidence: 5) [18] Kamiah A. Walker; Reviewed by Jason M. Highsmith, MD, Physical Therapy to Relieve Neck Pain (level of evidence: 5) [19] Portnoy HD. Anterior cervical discectomy and fusion. Surg neurol 2001; 56: 178-80 (level of evidence: 3A) [20] Watters et al. Anterior Cervical Discectomy With and Without Fusions Results, Complications, and long-term follow-up, Spine, 1994 (level of evidence: 2B)