Novel approach to meniscal vascularity evaluation using indocyanine green fluorescence-guided knee arthroscopy

Abstract

Objectives: This study aimed to use indocyanine green (ICG) fluorescence-guided knee arthroscopy to observe the meniscus and surrounding tissue vascularity and determine correlation with the patients' backgrounds. Currently, no data are available on the clinical application of ICG fluorescence-guided knee arthroscopy in assessing meniscal vascularity.

Design: Prospective, case series.

Setting: In-hospital settings.

Participants: 41 knees of 34 patients were examined. 4 knees of 4 patients were included in a pilot study for technique refinement only, while the remaining 37 knees of 30 patients were included in the study.

Main outcome measures: The times from ICG administration to fluorescence onset and fluorescence duration from onset to complete attenuation were recorded. The fluorescence intensity at the anterior, middle, and posterior segments of the meniscus was evaluated on a 4-point scale. The younger and older and smoker and non-smoker groups were compared.

Results: The average fluorescence onset time was 32.05 s, whereas the average fluorescence duration was 11 min 14 s. The age groups aged≤45 and ≥46 years showed an onset of 30±24.9 and 33.17±16.2 s and a duration of 12 min 54 s and 10 min 20 s, respectively. The smoking and non-smoking groups exhibited an onset of 28.33±14.4 and 33.84±21.5 s and a duration of 10 min 37 s and 11 min 32 s, respectively. All segments of the lateral meniscus showed higher fluorescence intensities than the medial. The posterior segment of the lateral meniscus at ≤45 was markedly more fluorescent and significantly different from ≥46.

Conclusions: Fluorescence was observed for approximately 30 s after intravenous ICG injection and lasted approximately 10 min. Fluorescence intensity was brighter in the posterior segment of the lateral meniscus, particularly at ≤45. ICG fluorescence-guided knee arthroscopy may assist in case-specific hemodynamics and real-time surgical evaluation of the meniscus in living humans.

Keywords: Arthroscopy; Development Study; Health Technology; Technology Assessment, Biomedical.

Figure 1. Schematic diagram showing vascularity in the meniscus. (A) Red–red zone: transition area of the meniscus and synovial capsule. (B) Red–white zone: the area between the red-red zone and the avascular zone. (C) White–white zone: avascular zone, considered extremely poor in vascularity.

Figure 2. Comparison between laparoscope and arthroscope. (A) Side-by-side length comparison between the arthroscope (140 mm length, 4.0 mm in diameter, upper row) and laparoscope (300 mm length, 5.4 mm in diameter, lower row), clearly demonstrating the greater length of the laparoscope. Intraoperative photographs: (B) using a laparoscope and (C) using an arthroscope. Differences in the field of view: the posterior horn of the lateral meniscus is visualized with the laparoscope (D) and the anterior horn of the lateral meniscus is observed with the arthroscope (E). Note: For panels (B) and (C), the endoscope was inserted through the medial portal, rather than the lateral portal used in the standard protocol, to provide a clearer visual comparison of the scopes.

Figure 3. Sequence of protocols for detection of fluorescence under arthroscopy. (A) The arthroscope is positioned from the point of view of the popliteal tendon using the lateral infrapatellar approach in ‘Figure-4’ position. (B) To ensure this condition, the camera system is switched to the ICG (ENV) mode while maintaining the state in (A). (C) After waiting for about 30 s, fluorescence appears in this area after 2.0 mL of ICG solution (2.5 mg/mL) has been administered intravenously. ENV, endoscopic near-infrared visualization; ICG, indocyanine green.

Figure 4. Observation of fluorescence brightness distribution: intensity evaluation levels. Level 0: no fluorescent. Level 1: no glowing green. Level 2: light fluorescent green. Level 3: bright fluorescence.

Figure 5. Fluorescence onset and duration in each group. (A) The fluorescence onset time results in all cases; the average onset time is 32.05 s. (B) Comparison of onset in ≤45 and ≥46 years. (C) Comparison of onset in smokers and non-smokers. (D) The fluorescence duration time results in all cases; the average duration is 11 min and 14 s. (E) Comparison of duration in ≤45 and ≥46 years. (F) Comparison of duration in smokers and non-smokers.

Figure 6. Fluorescence location and intensity levels in each group. (A) Fluorescence intensity levels in all cases. All segments of the lateral meniscus show higher fluorescence intensities than do those of the medial meniscus. (B,C) In the two groups divided by mean age, all sites show higher fluorescence at age≤45 years and lower fluorescence at age≥46 years in the lateral meniscus. (D,E) Among smokers and non-smokers, smokers exhibit lower intensity levels, particularly in the lateral meniscus. LM, lateral meniscus; MM, medial meniscus.