Near-infrared spectroscopy for arthroscopic evaluation of cartilage lesions: results of a blinded, prospective, interobserver study.
BACKGROUND
Mechanical tests to grade cartilage damage are limited by the instruments used and by the ability to access all areas of cartilage within a joint. Better methods to diagnose cartilage injury or degeneration are needed. Purpose/


OBJECTIVE
To detect the interobserver variance of arthroscopic cartilage grading by subjective judgment using the International Cartilage Repair Society (ICRS) score and by objective measurement using near-infrared (NIR) spectroscopy. We hypothesized that objective measurement of cartilage lesions by NIR spectroscopy will yield more valid results than routine grading using the ICRS score.


METHODS
Cohort study (diagnosis); Level of evidence, 2.


METHODS
Fifteen patients undergoing arthroscopic knee operations were evaluated by 4 experienced arthroscopists independently. The cartilage lesions within the medial knee compartment were estimated by each observer using the ICRS grade and by measurements with a special arthroscopic NIR spectroscopy probe.


RESULTS
The ICRS grading had a poor interobserver agreement, with a mean Fleiss kappa index of κ = 0.173. Only in 10% (6 of 60) of judged cartilage areas did all 4 surgeons grade the cartilage areas with the same result. In 17 areas (28.3%), the surgeons had a variance of 2 or more grades. In the remaining cases, the surgeons varied within 1 grade. The objective NIR spectroscopy-obtained measurements of cartilage resulted in a significant correlation within the observers of R = 0.885 ± 0.036 (P < .001).


CONCLUSIONS
Our results of interobserver evaluation in real-time arthroscopic cartilage grading suggest that this subjective grading is not satisfactory. This study emphasizes the need for objective measurement techniques for arthroscopic cartilage grading. Near-infrared spectroscopy has a good interobserver correlation. Thus, this method could be developed in the future as a precise method of measuring cartilage lesions.
Spahn
Gunter
G
Center of Trauma and Orthopaedic Surgery Eisenach, Germany. spahn@pk-eisenach.de
Klinger
Hans Michael
HM
Baums
Mike
M
Hoffmann
Martin
M
Plettenberg
Holger
H
Kroker
Anne
A
Hofmann
Gunther O
GO
D000328:Adult; D001182:Arthroscopy / Q000295:instrumentation* / Q000379:methods; D002357:Cartilage Diseases / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D002358:Cartilage, Articular / Q000293:injuries* / Q000473:pathology / Q000601:surgery; D016001:Confidence Intervals; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results; D016037:Single-Blind Method; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation / Q000379:methods; D013314:Stress, Mechanical; D055815:Young Adult