New study highlights outcomes of cervicothoracic junction instrumentation following separation surgery for spinal metastases

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Mark Bilsky

Instrumented fusion across the cervicothoracic junction (CTJ) demonstrated an 18.8% rate of postoperative complications and an 11% overall two-year rate of hardware failure in patients who underwent metastatic epidural tumour decompression and stabilisation, a recent study—published in the Journal of Neurosurgery: Spine by Mark Bilsky (Memorial Sloan Kettering Cancer Center, New York, USA) et al—has shown.

The CTJ “is a challenging region to stabilise after tumour resection for metastatic spine disease” state the researchers. As such, the study sought to describe the outcomes of patients who underwent posterolateral decompression and instrumented fusion.

The study authors performed a single-institution retrospective study of a prospectively collected cohort of patients who underwent single-approach posterior decompression and instrumented fusion across the CTJ for metastatic spine disease between 2011 and 2018. Adult patients (those aged 18 or over) who presented with mechanical instability, myelopathy, and radiculopathy secondary to metastatic epidural spinal cord compression (MESCC) of the CTJ (C7–T1) from 2011 to 2018 were included.

A total of 79 patients were included, with a mean age of 62.1 years. The most common primary malignancies were non–small cell lung (n= 17), renal cell (11), and prostate (8) carcinoma. The median number of levels decompressed and construct length were three and seven, respectively. The average operative time, blood loss, and length of stay were 179.2 minutes, 600.5 ml, and 7.7 days, respectively.

Overall, 58 patients received adjuvant radiation, and median dose, fractions, and time from surgery were 27 Gy, three fractions, and 20 days, respectively. All patients underwent lateral mass and pedicle screw instrumentation. Forty-nine patients had tapered rods (4/5.5 mm or 3.5/5.5 mm), 29 had fixed-diameter rods (3.5mm or 4mm), and one had both.

Ten patients required anterior reconstruction with poly-methyl-methacrylate (PMMA). The overall complication rate was 18.8% (six patients with wound-related complications, seven with hardware-related complications, one with both, and one with ‘other’). For the eight patients (10%) with hardware failure, seven had tapered rods, all eight had cervical screw pullout, and one patient also experienced rod/screw fracture.

The study also showed that the average time to hardware failure was 146.8 days and that the two-year cumulative incidence rate of hardware failure was 11.1% (95% CI 3.7%–18.5%). There were 55 deceased patients, and the median (95% CI) overall survival period was 7.97 (5.79–12.6) months. For survivors, the median (range) follow-up was 12.94 (1.94–71.80) months.

Speaking to Spinal News International, Bilsky said: “This study provides a benchmark using the screw-rod instrumentation strategies to bridge the CTJ in tumour reconstruction following separation surgery. Separation surgery followed by stereotactic radiosurgery, ie. hybrid therapy, has largely become the standard approach for metastatic spine tumours, especially at CTJ where anterior approaches have significant associated morbidity.

“Part of this increased failure rate over CTJ is explained by the anatomic stress of transitioning from the fixed, kyphotic thoracic spine to the mobile, lordotic cervical spine; however, there are additional stresses omnipresent in oncology such as difficulty achieving arthrodesis secondary to radiation and systemic therapy, multi-level lytic posterior element and vertebral body fractures, postoperative adjacent-segment tumour progression, fixed cervical and thoracic deformities, and commonly encountered  osteoporosis.

“We have largely adopted short-segment fixation with PMMA-augmented pedicle screws in the thoracic and lumbar spine resulting in a 2.3% failure rate requiring a reoperation.1 CTJ instrumentation strategies using fixed and tapered rods remains a work in evolution as our fixation failure rate is significantly higher at 11.1% with all failures being cervical-screw pullout of which 7/8 were tapered-rod constructs.

“As PMMA is not available for cervical-screw fixation, we will continue to evaluate other strategies increasing our use of fixed-rod constructs and evaluating the safe application of cervical pedicle screws. Ultimately, this failure rate may not decrease significantly for all the reasons noted, but fortunately effective salvage strategies at re-instrumentation are available for these patients.”

 

References:

1. Newman WC, Amin AG, Villavieja J, Laufer I, Bilsky MH, Barzilai O. Short-segment cement-augmented fixation in open separation surgery of metastatic epidural spinal cord compression: initial experience. Neurosurgery Focus May 2021;50(5): E11  


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