Migration of an Anterior Cervical Discectomy and Fusion Screw into the Constrictor Muscle of the Hypopharynx: A Case Report

Implant Migration After Anterior Cervical Spine Surgery: A Systematic Literature Review

STUDY DESIGN

Systematic literature review.

OBJECTIVE

To summarize the demographics, diagnosis, clinical course, management, and outcomes for implant migration after anterior cervical spine surgery.

SUMMARY OF BACKGROUND DATA

Implant migration following anterior cervical spine surgery is a rare event that may predispose patients to high morbidity due to the proximity of cervical implants to critical structures. Due to the infrequency of this complication, most of the literature on this topic is described in case reports or series.

METHODS

We screened the PubMed database for relevant publications from January 1975 to December 2023 using the terms: (screw OR hardware OR plate OR implant OR instrumentation) AND (pull-out OR migration OR displacement OR erosion OR perforation) AND (anterior cervical OR ACDF OR ACCF). The PRISMA systematic review template guided the identification and screening of full-text articles in English.

RESULTS

Fifty-five studies with 76 patients were included. The median age was 50.0 (32.0, 60.0) years, with a median time-to-diagnosis of 15 months (2.0, 60.8). Seventy-five percent were symptomatic, while 20% were asymptomatic. Common symptoms included dysphagia (54%), neck pain (22%), and fever or cervical abscess (13%). Treatments included complete implant removal (59%), partial removal (20%), spontaneous gastrointestinal elimination (11%), and retention of all instrumentation (5%). In addition, 25% underwent revision spinal fusion. Sixty-one percent experienced major complications (eg, perforation, fistula, abscess). However, 84% had resolution of symptoms without further treatment at the most recent follow-up.

CONCLUSIONS

Implant migration after anterior cervical spine surgery is rare yet may occur many years after a patient's initial surgery without heralding symptoms. For this reason, surgeons should consider extended routine follow-up with radiographic imaging in these patients, for the first 5 years postoperatively since this complication transpired most frequently within this time frame. We recommend an individualized, patient-centered approach for radiographic follow-up to balance the risk of unnecessary radiation exposure in addition to practical risks like travel-related accidents. Extended routine follow-up may be most beneficial for patients with identified risk factors for late complications or early migration, that is, complex deformity or poor bone quality.

Delayed Screw Migration Following Anterior Cervical Discectomy and Fusion

OBJECTIVE

To identify the clinical and surgical characteristics and treatment options of patients suffering delayed (>1 month) screw back-out after anterior cervical discectomy and fusion (ACDF).

METHODS

A systematic review was performed searching Embase, Medline, and Scopus for relevant case studies and case series of delayed screw back-out after ACDF.

RESULTS

A total of 25 studies encompassing 31 patients were identified and included. Average time to screw back-out was 4.6 years. Fifty-two percent of patients presented with dysphagia, and 61% had a pharyngoesophageal injury. Five patients were asymptomatic; 25 patients underwent surgery to remove hardware, 12 patients had surgical repair of the esophagus or hypopharynx, and 4 patients were managed conservatively. Antibiotic duration when given ranged from 2 weeks to 6 months. Nil per os (NPO) duration ranged from 4 days to 3 months.

CONCLUSIONS

The risk of screw back-out is low, but it can be a devastating complication. The majority of reported cases developed pharyngoesophageal injury and dysphagia. Surgery is often required to remove the hardware and repair any damage to the esophagus or hypopharynx, and may require prolonged antibiotics and NPO. Rarely, patients may be asymptomatic and treated conservatively; but in 7 patients in this series in whom back-out was initially managed conservatively there was worsening back-out or injury that occurred an average of 29 months later.