Durability of Endoscopes Used During Routine Lumbar Endoscopy: An Analysis of Use Patterns, Common Failure Modes, Impact on Patient Care, and Contingency Plans

The percentage breakdown of responses to survey questions on endoscope durability with multiple possible answers on practice, age, years of practice, and years of performing endoscopic spine surgery given by the 85 participating spine surgeons is shown. The majority of respondents were in private practice (55.3%) and aged between 35 and 54 years (76.5%). The minority (27.1%) were in practice for 5 years or less. However, most respondents (55.3%) had 5 years or less of clinical experience with the spinal endoscopy procedure.

Damage to the endoscope’s lens and working channel with mechanical burrs or drills (left top panel) resulting in blurry vision (top right panel) was a common intraoperative failure mode reported by many participating survey surgeons, who performed 89.4% of lumbar endoscopic decompression surgeries in a hospital. The surgical indication was herniated disc in 65.9% and spinal stenosis in the remaining 34.1% of operations in which respondents employed endoscopic decompression techniques. Only 23.5% of respondents worked in an organization with 10 or more spine surgeons. Most respondents (62.3%) were in smaller practice settings, with 5 or fewer peer spine surgeons. Multiple responses to these questions were allowed.

Only 25.9% of respondents were somewhat or very concerned with the possibility of the spinal endoscope breaking during surgery and considered alternate decompression procedures. Failure of spinal endoscopes was reported to be more likely during posterolateral (50.6%) as opposed to interlaminar (31.8%) or unilateral biportal endoscopic (UBE) (12.9%) surgery. The majority (76.5%) of respondents preferred transforaminal over interlaminar (51.8%), or UBE (15.3%). The vendor breakdown in decreasing order revealed respondents preferably used equipment made by Wolf/Riwo Spine™ (38.8%), Joimax™ (36.5%), Storz™ (24.7%), an unspecified Chinese brand (22.4%), Maxmore™/ InnoView GmbH (15.3%), Spinendos™ (12.9%), Elliquence™ (10.6%), an unspecified Korean brand (7.1%), asap endoscopic products GmbH (2.4%), and other unidentified vendors (2.4%). Multiple responses to these questions were allowed.

Shown are the axial (top left panel) and sagittal (top right panel) T2-weighted magnetic resonance imaging scans of a case of a 45-year-old woman who underwent transforaminal decompression for L4/5 spinal stenosis with a herniated disc. During the transforaminal decompression, the lens failed (bottom left panel), resulting in blurry vision (bottom right panel). An unidentified surgeon sent in this case example via the online survey tool exhibiting the broken endoscope (bottom left panel) and the resulting deterioration of endoscopic visualization of painful spinal pathology during a transforaminal decompression procedure.

Respondents indicated that the most commonly encountered problems with a spinal endoscope that failed during lumbar endoscopic decompression in decreasing order were blurry vision (71.8%), lack of optical focus (21.2%), and dim illumination (18.8%). Powered high-speed burrs were reported as the favorite decompression tools introduced through the endoscope’s inner working channel to accomplish decompression of the symptomatic neural elements (71.8% of respondents). Lens (67.1%) and light conductor (23.5%) failure were reported as the most commonly encountered problems. Multiple responses to these questions were allowed. More than half (52.9%) of respondents performed 100 or fewer cases per year concerning case volume. High-volume surgeons performed 150 or more endoscopic spine surgeries per year (37.6%).

To the authors' surprise, only 28.4% of respondents reported that their preferred spinal endoscope ordinarily lasts for 100 or more lumbar decompression surgeries before it has to be replaced. Typically, instructions for use provided by manufacturers suggests that their endoscope should withstand 150 to 200 operation and sterilization cycles. Actual usage numbers reported by rrespondents were operational life cycles of 21 to 36 surgeries (20%), 36 to 50 surgeries (22.4%), or less than 20 surgeries (7.1%), suggesting a significant variation in product quality and usage-related abuse by the surgeon and the staff at their respective surgical facilities. Surgeons suspected bad handling by staff was the most common reason (45.9%) why their favorite endoscope underperformed and failed earlier than its projected life cycle. Abuse by the surgeon (25.9%) or the wrong sterilization technique (21.2%) was reported as another possible explanation for early failure. Remarkably, 20% of respondents thought they had a low-quality product in their hands. Even more remarkable, 23.5% of respondents noted that the endoscope failed during their surgery, highlighting the need for backup equipment and contingency plans. The bottomright panel shows a microscopic view of a spinal endoscope whose manufacturer advertised superior quality related to the lens’s gold welding. Nevertheless, the lens detached from the endoscope had to be retrieved intraoperatively from the patient with a backup endoscope from a different manufacturer.

Illustrative examples of microscopic views provided by several vendors to responding survey surgeons who solicited estimates for repair on returns. Common usage-related problems include a scratched ocular (A), scratched working channel with tears (B), cracked lens (C), scratched and deformed outer tube (D), a cracked lens with a blurry view (E), and dented and torn inner working channel with perforations (F). In the latter example, the holes allow irrigation fluid to enter the tube housing the optical system.