Arthroscopic Evaluation of Knee Cartilage Using Optical Reflection Spectroscopy

Spectroscopic Quantitative Measurement of the Cartilage Surface using Arthroscopy Correlates with a Conventional Macroscopic Grading System

Purpose

To quantify the cartilage surface profile visualized during arthroscopic surgery and examine its clinical utility by comparing the results of quantitative measurements with a conventional grading system.

Methods

Fifty consecutive patients diagnosed with knee osteoarthritis and who underwent arthroscopic surgery were included in this study. A 4 K camera system was used, and the cartilage surface profile was visualized using the augmented reality imaging program. The highlighted image was displayed in 2 colors: black (the worn cartilage area) and green (the part where the cartilage thickness was maintained). The percentage of the green area was calculated using ImageJ and used as an index of cartilage degeneration. The quantitative value was statistically compared with the International Cartilage Repair Society (ICRS) grade as a conventional macroscopic evaluation.

Results

In the quantitative measurement, the median percentage of the green area was 60.7 at ICRS grades 0 and 1 (interquartile range [IQR], 67.3-51.0), 47.2 at grade 2 (IQR, 54.1-39.2), 36.5 at grade 3 (IQR, 43.2-30.4), and 34.0 at grade 4 (IQR, 38.5-29.3). There was a significant difference between the macroscopic grades, except for Grades 3 and 4. There was a significant negative correlation between macroscopic evaluation and quantitative measurement (r = -0.672, P < .001).

Conclusions

The quantitative measurement of the cartilage surface profile using the spectroscopic absorption technique was significantly correlated with the conventional macroscopic grading system and demonstrated fair to good inter-rater and intra-rater reliabilities.

Level of Evidence

Level II, diagnostic (prospective cohort study).

A digital method of measuring cartilage defects under an arthroscope

Measurements of cartilage defect size under an arthroscope are essential for prognosis and treatment decisions. A new method called arthroscopic measurement by computer graphics (ACG) was developed to accurately calculate the size of the cartilage under an arthroscope. This study aimed to validate the accuracy and utility of this method. In this controlled laboratory study, the ACG method was validated by measuring the sizes of three cartilage defects in a knee joint of a pig, using the following techniques: traditional arthroscopic measurement by ruler (TAR), ACG, incised measurement by computer graphics (ICG), and incised measurement by ruler (IR, control, gold standard). Measurements were conducted by two blinded trained observers. Intra- and inter-observer variabilities were determined by calculating the intra-class correlation coefficient (ICC). Consistency among TAR, ACG, ICG and IR was analyzed using the command "Concord" in Stata. For arthroscopic measurements using ACG and ICG, the overall ICC intra- and inter-observer values were 0.99 and 0.98, respectively, which showed excellent reproductivity. The concord value showed consistency of various approaches relative to the gold standard method. The average concord value for TAR was 0.813, and the average concord value for ACG and ICG was 0.886 and 0.917, respectively. ACG utilizes computer graphics for measuring the size of cartilage defects of any size under an arthroscope, without reconditioning the injured cartilage. ACG showed excellent intra- and inter-observer reproducibility and satisfactory accuracy. This method would make it possible to more accurately match the graft with the defect, thereby facilitating cartilage repair.

Infrared attenuated total reflection spectroscopic surface analysis of bovine-tail intervertebral discs after UV-light-activated riboflavin-induced collagen cross-linking

The tensile strength of the intervertebral disc (IVD) is mainly maintained by collagen cross-links. Loss of collagen cross-linking combined with other age-related degenerative processes contributes to tissue weakening, biomechanical failure, disc herniation and pain. Exogenous collagen cross-linking has been identified as an effective therapeutic approach for restoring IVD tensile strength. The current state-of-the-art method to assess the extent of collagen cross-linking in tissues requires destructive procedures and high-performance liquid chromatography. In this study, we investigated the utility of infrared attenuated total reflection (IR-ATR) spectroscopy as a nondestructive analytical strategy to rapidly evaluate the extent of UV-light-activated riboflavin (B2)-induced collagen cross-linking in bovine IVD samples. Thirty-five fresh bovine-tail IVD samples were equally divided into five treatment groups: (a) untreated, (b) cell culture medium Dulbecco's Modified Eagle's Medium only, (c) B2 only, (d) UV-light only and (e) UV-light-B2. A total of 674 measurements have been acquired, and were analyzed via partial least squares discriminant analysis. This classification scheme unambiguously identified individual classes with a sensitivity >91% and specificity >92%. The obtained results demonstrate that IR-ATR spectroscopy reliably differentiates between different treatment categories, and promises an excellent tool for potential in vivo, nondestructive and real-time assessment of exogenous IVD cross-linking.

Articular cartilage repair using autologous collagen-induced chondrogenesis (ACIC): a pragmatic and cost-effective enhancement of a traditional technique

PURPOSE

The autologous collagen-induced chondrogenesis technique is described, and the results of a 6-year follow-up clinical study using this technique are presented.

METHODS

30 patients with International Cartilage Repair Society (ICRS) Grade III/IVa symptomatic chondral defects of the knee treated with enhanced microdrilling using atelocollagen were prospectively examined in this clinical series. The median age of the patients was 39.0 years (range 19-61 years). Patients were followed up to 72 months. Clinical evaluation was performed using functional knee scores and radiologically. Both quantitative and qualitative assessments were performed.

RESULTS

Statistically significant and clinically relevant improvement was observed in 2 years and was sustained for the 6 years of the study observation. At 6 years, the mean Lysholm score was 79.7 (SD 6.8) compared to 52.6 (SD 10.7) pre-operatively (p < 0.05). The symptomatic Knee Injury and Osteoarthritis Outcome Score (KOOS) improved from 68.3 (SD 11.4) to 90.2 (SD 4.3) (p < 0.05). The subjective International Knee Documentation Committee (IKDC) also showed improvement from 39.1 (SD 4.1) to 81.6 (SD 7.8) (p  < 0.05). The calculated T2* relaxation times were 26.0 (SD 4.2) seconds and 30.3 (SD 6.2) seconds for the repair tissue and native cartilage, respectively. The average magnetic resonance observation of cartilage repair tissue (MOCART) score was 78.5 (SD 9.6) for all lesions.

CONCLUSION

The enhanced microdrilling using atelocollagen is an enhancement of the traditional microfracture method using an off-the-shelf product. When used to treat moderate to severe chondral lesions, this enhancement produces hyaline-like cartilage with a corresponding improvement in symptoms.

LEVEL OF EVIDENCE

IV.