Navigation-assisted unilateral biportal endoscopic resection of an osteophyte associated with delayed L5 radiculopathy following expandable cage shrinkage: a case report.
- 1Tokyo Spine Clinic, Tokyo, Japan.
- 2Department of Neurosurgery, The Jikei University Hospital, Tokyo, Japan.
Abstract
Expandable interbody cages are widely used in lumbar fusion because they restore disc height and segmental lordosis while facilitating indirect decompression. Mechanical complications including subsidence, pseudoarthrosis and revision surgery are recognised, and delayed postoperative loss of cage height (shrinkage) has recently been reported. An association between cage shrinkage and delayed osteophyte formation causing radiculopathy has not previously been described. We report such a case and describe the utility of navigation-assisted unilateral biportal endoscopy (UBE) in its treatment. A 74-year-old man presented with an eight-month history of persistent left L5 radicular pain and numbness following multiple lumbar fusion procedures, culminating in long-segment fixation from L3 to S2 with dual S2 alar-iliac screws and expandable cages at L4/5 and L5/S1. Osteoporosis was present (T-score -2.6). Serial computed tomography (CT) demonstrated a progressive reduction in L5/S1 cage height from 11.6 to 10.4 mm, with no comparable change at the other levels, followed by gradual formation of an osteophyte at the posterolateral aspect of the S1 vertebral body contacting the traversing left L5 nerve root. There was no screw loosening. Selective nerve root block confirmed clinical-radiological concordance. Revision surgery was performed using navigation-assisted UBE: the osteophyte was resected under navigation guidance, and a second expandable cage with iliac bone graft was added without cage exchange or screw revision. Operative time was 71 minutes. The visual analogue scale improved from 8 to 2 and the Oswestry Disability Index from 63 to 10 within one month. At six months there was no instrumentation failure, no further shrinkage and no recurrence of symptoms. Shrinkage of an expandable cage may be associated with delayed, atypically located osteophyte formation and radiculopathy even in the absence of screw loosening. Navigation-assisted UBE enabled safe and precise resection of the lesion in anatomy distorted by previous fusion. Surgeons should be aware that CT may be invaluable in identifying this treatable cause in patients who develop recurrent or unexplained radicular symptoms after expandable cage implantation.
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BibTeX
@article{kojima2026navigationassisted,
title = {{Navigation-assisted unilateral biportal endoscopic resection of an osteophyte associated with delayed L5 radiculopathy following expandable cage shrinkage: a case report.}},
author = {Alison Kenji Kojima and Daichi Kawamura and Satoshi Yamana and Hiroki Ohashi and Takeshi Umebayashi},
journal = {Journal of spine surgery (Hong Kong)},
year = {2026},
month = sep,
doi = {10.21037/jss-2026-0178},
url = {https://europepmc.org/article/MED/42996613},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Navigation-assisted unilateral biportal endoscopic resection of an osteophyte associated with delayed L5 radiculopathy following expandable cage shrinkage: a case report.
AU - Alison Kenji Kojima
AU - Daichi Kawamura
AU - Satoshi Yamana
AU - Hiroki Ohashi
AU - Takeshi Umebayashi
PY - 2026
DA - 2026/09/29
JO - Journal of spine surgery (Hong Kong)
DO - 10.21037/jss-2026-0178
UR - https://europepmc.org/article/MED/42996613
AB - Expandable interbody cages are widely used in lumbar fusion because they restore disc height and segmental lordosis while facilitating indirect decompression. Mechanical complications including subsidence, pseudoarthrosis and revision surgery are recognised, and delayed postoperative loss of cage height (shrinkage) has recently been reported. An association between cage shrinkage and delayed osteophyte formation causing radiculopathy has not previously been described. We report such a case and describe the utility of navigation-assisted unilateral biportal endoscopy (UBE) in its treatment. A 74-year-old man presented with an eight-month history of persistent left L5 radicular pain and numbness following multiple lumbar fusion procedures, culminating in long-segment fixation from L3 to S2 with dual S2 alar-iliac screws and expandable cages at L4/5 and L5/S1. Osteoporosis was present (T-score -2.6). Serial computed tomography (CT) demonstrated a progressive reduction in L5/S1 cage height from 11.6 to 10.4 mm, with no comparable change at the other levels, followed by gradual formation of an osteophyte at the posterolateral aspect of the S1 vertebral body contacting the traversing left L5 nerve root. There was no screw loosening. Selective nerve root block confirmed clinical-radiological concordance. Revision surgery was performed using navigation-assisted UBE: the osteophyte was resected under navigation guidance, and a second expandable cage with iliac bone graft was added without cage exchange or screw revision. Operative time was 71 minutes. The visual analogue scale improved from 8 to 2 and the Oswestry Disability Index from 63 to 10 within one month. At six months there was no instrumentation failure, no further shrinkage and no recurrence of symptoms. Shrinkage of an expandable cage may be associated with delayed, atypically located osteophyte formation and radiculopathy even in the absence of screw loosening. Navigation-assisted UBE enabled safe and precise resection of the lesion in anatomy distorted by previous fusion. Surgeons should be aware that CT may be invaluable in identifying this treatable cause in patients who develop recurrent or unexplained radicular symptoms after expandable cage implantation.
SN - 2414-469X
SN - 2414-4630
ER -