Outcomes of occipitocervical fixation using a spinous process screw in C2 as a third anchor point for occipitocervical fixation: a case presentation

Unexpected Neurological Deterioration Following Occipitocervical Fusion Surgery: A Case Report

Occipitocervical posterior decompression and fusion (O-C fusion) surgery is occasionally required for treating high cervical myelopathy due to atlantoaxial subluxation. The advance of the instrumentation systems has led to favorable clinical outcomes following O-C fusion surgery. However, the rate of perioperative complications in O-C fusion surgery is relatively high, including instrumentation failure, respiratory complications, and dysphagia. Here we report a rare case involving an unexpected deterioration of myelopathy following O-C fusion surgery. A 49-year-old male was transported to our hospital by ambulance with left-sided upper and lower limb paralysis. At the initial visit, a neurological examination revealed left upper limb weakness (manual muscle testing (MMT) grade 2). X-ray and CT revealed severe atlantoaxial subluxation due to os odontoideum, while MRI revealed significant spinal cord compression at the C2 level. On the diagnosis of acute exacerbation of high cervical myelopathy, an O-C2 posterior decompression and fusion surgery, including C1 laminectomy, was performed. Postoperatively, the patient exhibited a deterioration in right-sided upper limb paralysis (MMT grade 2), despite proper implant placement confirmed by CT. During two weeks postoperatively, there was no improvement in the right-sided upper limb paralysis, and bilateral deep sensory impairment worsened. Follow-up X-rays revealed a progressive decrease in the O-C2 angle, and dynamic X-ray imaging demonstrated a recurrence of instability at the O-C2 level. On the diagnosis of the instrumentation failure, a revision surgery was performed three weeks after the primary surgery. Intraoperative findings revealed instability at the C2 screw head and loosening of the set screw on the C2 screw head. To achieve a more secure fixation, we extended the fusion to C4 with a triple rod connection. Following the revision surgery, his myelopathy and paralysis gradually improved. At the final follow-up, six months after surgery, X-rays showed that O-C2 was firmly stabilized. In conclusion, screw head fixation close to the O-C rod bending site may result in unexpected instrumentation failure in O-C fusion surgery.

A Review of Strategies to Improve Biomechanical Fixation in the Cervical Spine

STUDY DESIGN

Systematic review.

OBJECTIVES

Review the surgical techniques and construct options aimed at improving the biomechanical strength of cervical constructs.

METHODS

A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A search of the MEDLINE, Embase, and Cochrane Library databases was performed to identify all studies examining biomechanical strategies utilized in the osteoporotic cervical spine. Screening was performed in duplicate for all stages of the review process.

RESULTS

An initial search returned 3887 articles. After deletion of duplications and review of abstracts and full text, 39 articles met inclusion criteria. Overall, the surgical techniques reviewed aimed at obtaining rigid fixation in the setting of poor bone quality, or dispersing the forces at the bone-implant interface. We identified 6 key techniques to improve biomechanical fixation. These include bicortical fixation, appropriate screw selection (size and trajectory), PMMA augmentation, load sharing techniques, consideration of ancillary fixation around the occipitocervical junction, and supplementing the construct with post-operative collar or halo.

CONCLUSION

The summation of the literature highlights a framework of modalities available to surgeons to improve biomechanical fixation in the cervical spine. While these may improve construct strength in the setting of osteoporosis, there is a paucity of evidence available to make recommendations in this patient population.

A Novel Technique for Occipitocervical Fusion With Triple Rod Connection to Prevent Implant Failure

Occipitocervical fusion is an effective surgical method for treating various upper cervical disorders. However, complications such as implant failure due to rod breakage have been reported. Therefore, we devised a surgical technique for occipitocervical fusion with a triple rod connection to prevent implant failure. Occipitocervical fusion with triple rod connection was performed in two cases with a high risk of instability such as athetoid cerebral palsy and rheumatoid arthritis. A multiaxial screw (diameter: 4.5 mm) was inserted into the screw hole in the middle of the occipital plate, and subsequently, an additional rod was attached. It was connected to the main rod using an offset connector at the caudal side. The connection of the additional rod was simple and did not interfere with the fusion bed for bone graft between the occipital bone and axis. The head of the screw was crimped to the occipital plate, and the plate was firmly fixed. Moreover, since the head of the screw did not protrude to the dorsal side, the tension of the soft tissue and skin did not increase. No complications occurred after surgery in both cases. In addition, no special instruments were required to connect the additional rod to the main rod in this procedure. Therefore, our technique may be useful as an option to prevent implant failure due to rod breakage at the craniocervical junction.

4-Point C2 Fixation for Occipitocervical Fusion: Technical Case Report

BACKGROUND

Occipitocervical fusion is an important surgical procedure to treat instability of the upper cervical and craniocervical junction. Fixation to the dense cortical bone of the occiput, contemporaneously typically accomplished with a plate and screws, is known to be strong and durable, but there are many competing methods used to secure an adequate number of fixation points of sufficient strength at the cervical end. Extension of hardware to the midcervical region to acquire additional fixation points, however, results in loss of subaxial motion segments and additional potential morbidity. The C2 vertebra is unique in that its morphology and dimensions permit fixation with longer screws than are typically possible to place in the midcervical lateral masses. Translaminar and pars screw techniques, both commonly used to achieve C2 fixation, are not mutually exclusive, as their respective trajectories are considerably different and engage different portions of the bony anatomy.

METHODS

We describe a novel, 4-point C2 fixation technique for OC fusion that may avoid the need to extend fusion to the subaxial spine.

RESULTS

This technical note illustrates how 4-point C2 fixation can be employed in occiptocervical fusion.

CONCLUSIONS

4-point fixation of C2 combining translaminar and pars screw placement is technically feasible and may be a suitable strategy to spare subaxial motion segments in OC fusion procedures. Futher investigation may establish its applicability to additional surgical procedures.