Reliability in arthroscopic grading of cartilage lesions: results of a prospective blinded study for evaluation of inter-observer reliability

Arthroscopic Electromechanical Assessment of Human Articular Cartilage Injury Correlates with ICRS Scores

PURPOSE

This study aimed to conduct arthroscopic evaluation of cartilage electromechanical properties and establish their correlation with International Cartilage Repair Society (ICRS) grading scores.

METHODS

In 18 patients, quantitative parameter (QP) measurements were taken on the weight-bearing surface of the medial femoral condyle. Adjacently, the same site was graded using ICRS scores (0-4). Electromechanical QPs for ICRS grades 0 to 3 were obtained during arthroscopy, while complete grade 4 injuries were assessed using femur cartilage-bone blocks from knee arthroplasty. The QP values for ICRS grades 0 to 2 were compared with grades 3 and 4 using Welch t test. The corresponding QP values were assigned to ICRS grades 0 to 4 and compared using Welch ANOVA (analysis of variance). Pearson's coefficient evaluated QP-ICRS grade relationship.

RESULTS

Healthy grade 0 cartilage displayed a mean QP value of 10.5 (±2.8 SD, n = 4). The ICRS grade 1 and grade 2 injuries were associated with QP values of 12 (±0.7, n = 2) and 13.25 (±1.77, n = 2), respectively. The grade 3 defects had QP values of 20.43 (±4.84, n = 4), whereas complete grade 4 defects showed electromechanical values of 30.17 (±2.19, n = 6). Significant differences in QP values were observed between ICRS grades 0 to 2 (mean QP 11.56 ± 2.3, n = 8) and grades 3 and 4 (26.27 ± 6, n = 10; P < 0.0001). Pearson's correlation coefficient of 0.9 indicated a strong association between higher ICRS cartilage injury grades and elevated QP values (P < 0.0001).

CONCLUSION

Arthroscopic electromechanical QP assessment robustly correlates with ICRS scores. The QP values for ICRS grades 0 to 2 are significantly lower, compared with grades 3 and 4.

Reliability and Accuracy of the Outerbridge Classification in Staging of Cartilage Defects

OBJECTIVE

The decision on whether or not and how to treat a local cartilage defect is still made intraoperatively based on the visual presentation of the cartilage and findings from indentations with an arthroscopic probe. The treatment decision is then usually based on grading according to established classifications systems, which, therefore, need to have high reliability and accuracy. The aim of the present study was to evaluate the reliability and accuracy of the Outerbridge classification in staging cartilage defects.

METHODS

We performed an observer arthroscopic study using the Outerbridge classification on seven fresh-frozen human cadaveric knees, which collectively exhibited nine cartilage defects. To evaluate accuracy, defect severity was verified through histological examination. Interrater and intrarater reliabilites were calculated using Cohen's kappa and the intra-class correlation coefficient (ICC 3.1).

RESULTS

The interrater and intrarater reliability for the Outerbridge classification ranged from poor to substantial, with 0.24 ≤ κ ≤ 0.70 and κ = 0.55 to κ = 0.66, respectively. The accuracy evaluated by comparison with the histological examination was 63% overall. The erroneous evaluations were, however, still often at the discrimination of grade 2 and 3. We did not find any relationship between higher experience and accuracy or intraobserver reliability. Taken together, these results encourage surgeons to further use diagnostic arthroscopy for evaluating cartilage lesions. Nevertheless, especially in grade 2 and 3, deviations from the histology were observed. This is, however, the point where a decision is made on whether to surgically address the defect or not.

CONCLUSION

Diagnostic arthroscopy is the standard for cartilage lesion assessment, yet interobserver reliability is fair to substantial. Caution is warranted in interpreting varied observer results. The accuracy of the "simpler" Outerbridge classification is insufficient compared to histological examinations, highlighting the need for improved techniques in guideline-based intraoperative decision-making.

The relevance of knee arthroscopy photographs in medicolegal proceedings

PURPOSE

Whether photographs included in the operative report of knee arthroscopies can make the surgeon liable in the event of a legal investigation remains unknown. The main objective of this study was to establish inter-observer reliability in determining the presence or absence of lesions of the cartilage, meniscus and anterior cruciate ligament (ACL). Secondary objective was to assess the inter-observer reliability in classifying lesions.

METHOD

A retrospective observational study was conducted in a continuous serie of 60 patients who underwent knee arthroscopy from the same operator. The photographs of each patient's operative report were presented separately to three experts, blinded to each other. Each expert had to decide on the presence or absence of injuries to the following structures: meniscal, cartilage and ACL and then, classify it. Primary and secondary endpoints were evaluated using the Fleiss' kappa index.

RESULTS

Inter-observer reliability for lesion detection was between 0.4 and 0.61 for all structures with three exceptions: for cartilage, it was low (0.15) at the lateral tibial plateau and poor (-0.01) at the external condyle. On the contrary, the concordance was almost perfect (0.8) for the ACL. For classifying cartilaginous and meniscal lesions, inter-observer reliability was poor (from 0.03 to 0.14), except for at the lateral meniscus (0.65).

CONCLUSION

Inter-observer reliability of arthroscopic knee diagnoses is poor when photographs alone are used. In the event of a legal investigation following knee arthroscopy, the photographs included in the operative report should not be used alone to hold the surgeon liable.

Functional Assessment of Human Articular Cartilage Using Second Harmonic Generation (SHG) Imaging: A Feasibility Study

Many arthroscopic tools developed for knee joint assessment are contact-based, which is challenging for in vivo application in narrow joint spaces. Second harmonic generation (SHG) laser imaging is a non-invasive and non-contact method, thus presenting an attractive alternative. However, the association between SHG-based measures and cartilage quality has not been established systematically. Here, we investigated the feasibility of using image-based measures derived from SHG microscopy for objective evaluation of cartilage quality as assessed by mechanical testing. Human tibial plateaus harvested from nine patients were used. Cartilage mechanical properties were determined using indentation stiffness (Einst) and streaming potential-based quantitative parameters (QP). The correspondence of the cartilage electromechanical properties (Einst and QP) and the image-based measures derived from SHG imaging, tissue thickness and cell viability were evaluated using correlation and logistic regression analyses. The SHG-related parameters included the newly developed volumetric fraction of organised collagenous network (Φcol) and the coefficient of variation of the SHG intensity (CVSHG). We found that Φcol correlated strongly with Einst and QP (ρ = 0.97 and - 0.89, respectively). CVSHG also correlated, albeit weakly, with QP and Einst, (|ρ| = 0.52-0.58). Einst and Φcol were the most sensitive predictors of cartilage quality whereas CVSHG only showed moderate sensitivity. Cell viability and tissue thickness, often used as measures of cartilage health, predicted the cartilage quality poorly. We present a simple, objective, yet effective image-based approach for assessment of cartilage quality. Φcol correlated strongly with electromechanical properties of cartilage and could fuel the continuous development of SHG-based arthroscopy.

Intraoperative arthroscopic classification tool for posterolateral elbow instability

Background

Introducing and implementing an arthroscopic classification tool for posterolateral elbow instability.

Methods

Thirty arthroscopies were performed on 30 patients, and all recordings were collected, blinded, and labeled. Three orthopedic surgeons reviewed and scored all 30 recordings three times with a period of at least seven days in between to analyze the intraobserver and interobserver reliability. The classification consisted of five different grades.

Results

Indications for elbow arthroscopy included impingement (n = 7), osteochondritis dissecans (n = 5), pain (n = 7), osteoarthritis (n = 6), and other (n = 5). The kappa value for intrarater reliability was 0.71, indicating good reliability, while the kappa value for inter-rater reliability was 0.38 indicating fair reliability.

Conclusion

This new classification is a tool for an arthroscopic assessment of PLRI and can be used as a standardized grading system for further research and communication between orthopedic surgeons. We demonstrated good intrarater reliability (k = 0.71) with fair inter-rater reliability (k = 0.38). However, further research is necessary to study the clinical significance.

Characterisation of Cartilage Damage via Fusing Mid-Infrared, Near-Infrared, and Raman Spectroscopic Data

Mid-infrared spectroscopy (MIR), near-infrared spectroscopy (NIR), and Raman spectroscopy are all well-established analytical techniques in biomedical applications. Since they provide complementary chemical information, we aimed to determine whether combining them amplifies their strengths and mitigates their weaknesses. This study investigates the feasibility of the fusion of MIR, NIR, and Raman spectroscopic data for characterising articular cartilage integrity. Osteochondral specimens from bovine patellae were subjected to mechanical and enzymatic damage, and then MIR, NIR, and Raman data were acquired from the damaged and control specimens. We assessed the capacity of individual spectroscopic methods to classify the samples into damage or control groups using Partial Least Squares Discriminant Analysis (PLS-DA). Multi-block PLS-DA was carried out to assess the potential of data fusion by combining the dataset by applying two-block (MIR and NIR, MIR and Raman, NIR and Raman) and three-block approaches (MIR, NIR, and Raman). The results of the one-block models show a higher classification accuracy for NIR (93%) and MIR (92%) than for Raman (76%) spectroscopy. In contrast, we observed the highest classification efficiency of 94% and 93% for the two-block (MIR and NIR) and three-block models, respectively. The detailed correlative analysis of the spectral features contributing to the discrimination in the three-block models adds considerably more insight into the molecular origin of cartilage damage.

Near-Infrared Spectroscopy Enables Arthroscopic Histologic Grading of Human Knee Articular Cartilage

Purpose

To develop the means to estimate cartilage histologic grades and proteoglycan content in ex vivo arthroscopy using near-infrared spectroscopy (NIRS).

Methods

In this experimental study, arthroscopic NIR spectral measurements were performed on both knees of 9 human cadavers, followed by osteochondral block extraction and in vitro measurements: reacquisition of spectra and reference measurements (proteoglycan content, and three histologic scores). A hybrid model, combining principal component analysis and linear mixed-effects model (PCA-LME), was trained for each reference to investigate its relationship with in vitro NIR spectra. The performance of the PCA-LME model was validated with ex vivo spectra before and after the exclusion of outlying spectra. Model performance was evaluated based on Spearman rank correlation (ρ) and root-mean-square error (RMSE).

Results

The PCA-LME models performed well (independent test: average ρ = 0.668, RMSE = 0.892, P < .001) in the prediction of the reference measurements based on in vitro data. The performance on ex vivo arthroscopic data was poorer but improved substantially after outlier exclusion (independent test: average ρ = 0.462 to 0.614, RMSE = 1.078 to 0.950, P = .019 to .008).

Conclusions

NIRS is capable of nondestructive evaluation of cartilage integrity (i.e., histologic scores and proteoglycan content) under similar conditions as in clinical arthroscopy.

Clinical Relevance

There are clear clinical benefits to the accurate assessment of cartilage lesions in arthroscopy. Visual grading is the current standard of care. However, optical techniques, such as NIRS, may provide a more objective assessment of cartilage damage.

Assessing collagen alterations in enzymatic degradation models of osteoarthritis via second harmonic generation microscopy

INTRODUCTION

Structural changes in the collagen II architecture of osteoarthritis (OA) are poorly understood, which is a large shortcoming in the early diagnosis of this disease. Though degradation can be simulated by enzymes including trypsin and bacterial collagenase, the specific structural features of each digestion and their relationship to naturally occurring OA remain unclear.

EXPERIMENTAL DESIGN

We used collagen sensitive/specific Second Harmonic Generation (SHG) microscopy in conjunction with optical scattering measurements to probe the resulting architecture changes in bovine knee cartilage upon trypsin and collagenase degradation. Image features extracted from SHG images were used to train a linear discriminant (LD) model capable of classifying enzymatic degradation, which was then applied to human cartilage with varied modified Mankin histological scores.

RESULTS

The treatment of cartilage with these enzymes resulted in more disorganized collagen structure, where this effect was greatest with collagenase treatment. Using the LD model, we classified the control and degraded tissues in the three zones with >92% accuracy, showing that these enzymes have distinct activity on the collagen assembly. Application of the LD model to human cartilage indicated that collagenase effects were more representative of in vivo degeneration and were also consistent with damage beginning at the articular surface and progressing into deeper zones.

CONCLUSIONS

SHG and optical scattering measurements successfully delineate trypsin and collagenase degradation and suggest that collagen alterations in human OA are better simulated by the latter mechanism. These results lay the groundwork for using high-resolution SHG and optical scattering as an earlier diagnostic tool than is currently available.

Comparison of properties determined using electromechanical assessment (Arthro-BST™) with macroscopic and histological properties in symptomatic human articular cartilage of the hip

BACKGROUND

Cartilage degeneration is assessed using various methods. Although macroscopic evaluation can directly measure cartilage degeneration, it cannot accurately assess cartilage properties. Histological examination is one of the most accurate methods for evaluating cartilage degeneration. However, it is invasive and requires collection of cartilage tissue. In contrast, the Arthro-BST™ probe can assess cartilage properties noninvasively. This study aimed to evaluate the effectiveness of the Arthro-BST in assessing cartilage degeneration by comparing macroscopic (International Cartilage Repair Society [ICRS] classification) and histological evaluations (modified Mankin score and Osteoarthritis Research Society International [OARSI] histological grade).

METHODS

Fourteen femoral heads were excised from 13 patients during surgery to treat hip osteoarthritis or femoral fracture. The ICRS score was used for macroscopic evaluation of cartilage degeneration. The Arthro-BST was applied at sites matching the areas of cartilage damage. The sites assessed using the ICRS classification and Arthro-BST were evaluated histologically (modified Mankin score and OARSI histological grade), and these were compared with the Arthro-BST results.

RESULTS

The ICRS classification identified significant differences between grades 1 and 3 (p < 0.01), between grades 1 and 4 (p < 0.01), between grades 2 and 3 (p < 0.01), and between grades 2 and 4 (p < 0.01). Significant correlations were observed between the Arthro-BST results and the ICRS score, modified Mankin score (structure, cellularity, matrix staining, total score), and OARSI histological grade.

CONCLUSIONS

In the assessment of hip osteoarthritis, the Arthro-BST results correlated with those of macroscopic and histological evaluations. The Arthro-BST is useful for assessing hip osteoarthritis and may be helpful for noninvasive assessment of cartilage degeneration.

Machine learning augmented near-infrared spectroscopy: In vivo follow-up of cartilage defects

OBJECTIVE

To assess the potential of near-infrared spectroscopy (NIRS) for in vivo arthroscopic monitoring of cartilage defects.

METHOD

Sharp and blunt cartilage grooves were induced in the radiocarpal and intercarpal joints of Shetland ponies and monitored at baseline (0 weeks) and at three follow-up timepoints (11, 23, and 39 weeks) by measuring near-infrared spectra in vivo at and around the grooves. The animals were sacrificed after 39 weeks and the joints were harvested. Spectra were reacquired ex vivo to ensure reliability of in vivo measurements and for reference analyses. Additionally, cartilage thickness and instantaneous modulus were determined via computed tomography and mechanical testing, respectively. The relationship between the ex vivo spectra and cartilage reference properties was determined using convolutional neural network.

RESULTS

In an independent test set, the trained networks yielded significant correlations for cartilage thickness (ρ = 0.473) and instantaneous modulus (ρ = 0.498). These networks were used to predict the reference properties at baseline and at follow-up time points. In the radiocarpal joint, cartilage thickness increased significantly with both groove types after baseline and remained swollen. Additionally, at 39 weeks, a significant difference was observed in cartilage thickness between controls and sharp grooves. For the instantaneous modulus, a significant decrease was observed with both groove types in the radiocarpal joint from baseline to 23 and 39 weeks.

CONCLUSION

NIRS combined with machine learning enabled determination of cartilage properties in vivo, thereby providing longitudinal evaluation of post-intervention injury development. Additionally, radiocarpal joints were found more vulnerable to cartilage degeneration after damage than intercarpal joints.

Impact-induced cartilage damage assessed using polarisation-sensitive optical coherence tomography

Non-invasive determination of structural changes in articular cartilage immediately after impact and rehydration provides insight into the response and recovery of the soft tissue, as well as provides a potential methodology for clinicians to quantify early degenerative changes. In this study, we use polarisation-sensitive optical coherence tomography (PS-OCT) to examine subtle alterations of the optical properties in healthy and early-stage degenerate articular cartilage immediately after impact loading to identify structurally relevant metrics required for understanding the mechanical factors of osteoarthritic initiation and progression. A custom-designed impact testing rig was used to deliver 0.9 J and 1.4 J impact energies to bovine articular cartilage. A total of 52 (n=26 healthy, n=26 mildly degenerate) cartilage-on-bone samples were imaged before, immediately after, and 3 h after impact. PS-OCT images were analyzed to assess changes relating to surface irregularity, optical attenuation, and birefringence. Mildly degenerate cartilage exhibits a significant change in birefringence following 1.4 J impact energies compared to healthy samples which is believed to be attributable to degenerate cartilage being unable to fully utilise the fluid phase to distribute and dampen the energy. After rehydration, the polarisation-sensitive images appear to 'optically-recover' reducing the reliability of birefringence as an absolute metric. Surface irregularity and optical attenuation encode diagnostically relevant information and may serve as markers to predict the mechanical response of articular cartilage. PS-OCT with its ability to non-invasively image the sub-surface microstructural abnormalities of cartilage presents as an ideal modality for cartilage degeneration assessment and identification of mechanically vulnerable tissue.

Dataset on equine cartilage near infrared spectra, composition, and functional properties

Near infrared (NIR) spectroscopy is a well-established technique that is widely employed in agriculture, chemometrics, and pharmaceutical engineering. Recently, the technique has shown potential in clinical orthopaedic applications, for example, assisting in the diagnosis of various knee-related diseases (e.g., osteoarthritis) and their pathologies. NIR spectroscopy (NIRS) could be especially useful for determining the integrity and condition of articular cartilage, as the current arthroscopic diagnostics is subjective and unreliable. In this work, we present an extensive dataset of NIRS measurements for evaluating the condition, mechanical properties, structure, and composition of equine articular cartilage. The dataset contains NIRS measurements from 869 different locations across the articular surfaces of five equine fetlock joints. A comprehensive library of reference values for each measurement location is also provided, including results from a mechanical indentation testing, digital densitometry imaging, polarized light microscopy, and Fourier transform infrared spectroscopy. The published data can either be used as a model of human cartilage or to advance equine veterinary research.

Contrast-enhanced computed tomography (CECT) attenuation is associated with stiffness of intact knee cartilage

Contrast-enhanced computed tomography (CECT) using charged contrast-agents enables quantification of cartilage glycosaminoglycan content. Since glycosaminoglycan content is a key determinant of cartilage compressive stiffness, CECT measurements have the potential to non-invasively assess cartilage stiffness. The objective of this study was to determine whether CECT attenuation, using a cationic contrast-agent (CA4+), correlates with the stiffness of intact cartilage. Six fresh femoral and six fresh tibial compartments with intact cartilage were obtained from patients undergoing total knee replacement surgery. The instantaneous stiffness was determined for 25-50 points on the surface of each compartment using an established indentation technique. The samples were then immersed in CA4+ solution for 48 h, scanned in a micro-CT scanner, and the average CECT attenuation at each indentation site was found for the superficial cartilage. A significant (p < 0.01) and positive correlation was observed between stiffness and CECT attenuation for sites from each individual cartilage surface, with correlation coefficients ranging from r = 0.37-0.57 and r = 0.48-0.69 (p < 0.01) for the tibia and femur, respectively. When data for each type of cartilage surface were pooled together, the correlation coefficients were r = 0.73 for femoral condyle data points and r = 0.49 for tibial plateau data points. CECT provided a map of cartilage stiffness across each surface, which allows regions of low stiffness to be identified. These findings support continued evaluation and development of quantitative imaging techniques to assess the functional properties of cartilage. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2641-2647, 2018.

An Evaluation of the Reliability of Wrist Arthroscopy in the Assessment of Tears of the Triangular Fibrocartilage Complex

PURPOSE

Wrist arthroscopy is generally considered the reference standard in the diagnosis of triangular fibrocartilage complex (TFCC) injuries. There is a paucity of data examining the reliability of wrist arthroscopy as a diagnostic modality for TFCC injuries. The goal of this study was to evaluate the interobserver and intraobserver reliability of the diagnosis of TFCC pathology during wrist arthroscopy.

METHODS

Twenty-five intraoperative digital videos were captured by the senior author during diagnostic and surgical arthroscopy of the wrist joint for known or suspected articular pathology. The senior author (P.K.B.) confirmed TFCC resilience on visual inspection and ballottement (trampoline effect) to make the diagnosis. Two videos were excluded for poor quality and inadequate visualization. Three hand surgeons subsequently reviewed the remaining 23 videos in a blinded fashion at 2 time points separated by 4 weeks. The reviewers determined if the trampoline test was positive and if a TFCC tear was present. Tears were classified using a morphologic classification. Statistical measures of reliability including percentage agreement and κ coefficients were calculated.

RESULTS

Agreement between observers for the presence or absence of a tear was 66.7%. The average intraobserver agreement regarding the presence or absence of a tear was 67.4% The kappa value for interobserver agreement was 0.33, whereas the intrarater agreement was 0.88. The 3 reviewers identified an average of 11.3 positive trampoline tests. Agreement between observers for a positive trampoline test was 65.2%. The average percentage of intraobserver agreement regarding a positive trampoline test was 49.3%. In cases where all 3 reviewers agreed on the presence of a TFCC tear, the agreement regarding tear location was 76.6%.

CONCLUSIONS

Wrist arthroscopy remains instrumental in the treatment of TFCC tears. However, given that inter-rater reliability in the assessment of these tears is probably too low, reconsideration should be given to arthroscopy as the reference standard in the diagnosis of these tears.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic III.

Electromechanical properties of human osteoarthritic and asymptomatic articular cartilage are sensitive and early detectors of degeneration

OBJECTIVE

To evaluate cross-correlations of ex vivo electromechanical properties with cartilage and subchondral bone plate thickness, as well as their sensitivity and specificity regarding early cartilage degeneration in human tibial plateau.

METHOD

Six pairs of tibial plateaus were assessed ex vivo using an electromechanical probe (Arthro-BST) which measures a quantitative parameter (QP) reflecting articular cartilage compression-induced streaming potentials. Cartilage thickness was then measured with an automated thickness mapping technique using Mach-1 multiaxial mechanical tester. Subsequently, a visual assessment was performed by an experienced orthopedic surgeon using the International Cartilage Repair Society (ICRS) grading system. Each tibial plateau was finally evaluated with μCT scanner to determine the subchondral-bone plate thickness over the entire surface.

RESULTS

Cross-correlations between assessments decreased with increasing degeneration level. Moreover, electromechanical QP and subchondral-bone plate thickness increased strongly with ICRS grade (ρ = 0.86 and ρ = 0.54 respectively), while cartilage thickness slightly increased (ρ = 0.27). Sensitivity and specificity analysis revealed that the electromechanical QP is the most performant to distinguish between different early degeneration stages, followed by subchondral-bone plate thickness and then cartilage thickness. Lastly, effect sizes of cartilage and subchondral-bone properties were established to evaluate whether cartilage or bone showed the most noticeable changes between normal (ICRS 0) and each early degenerative stage. Thus, the effect sizes of cartilage electromechanical QP were almost twice those of the subchondral-bone plate thickness, indicating greater sensitivity of electromechanical measurements to detect early osteoarthritis.

CONCLUSION

The potential of electromechanical properties for the diagnosis of early human cartilage degeneration was highlighted and supported by cartilage thickness and μCT assessments.

Qualitative and quantitative assessment of cartilage degeneration using full-field optical coherence tomography ex vivo

OBJECTIVE

The purpose of this study was to investigate the ability of full-field optical coherence tomography (FFOCT) to qualitatively and quantitatively evaluate cartilage degeneration using the qualitative evaluation of histology sections as the reference.

DESIGN

Thirty-three human knee cartilage samples of variable degeneration were included in the study. A closely matching histology and FFOCT image was acquired for each sample. The cartilage degeneration was qualitatively evaluated by assigning a grade to each histology and FFOCT image. The relevance of the performed grading was assessed by calculating the intra- and inter-observer reproducibility and calculating the concordance between the histology and FFOCT grades. A near-automatic algorithm was developed to quantitatively characterize the cartilage surface in each image. The correlation between the quantitative results and the reference qualitative histology was calculated.

RESULTS

An almost perfect agreement was achieved for both the intra- and inter-reproducibility of the histology and FFOCT qualitative grading (κ ≥ 0.91). A high and statistically significant level of agreement was measured between the histology and FFOCT grades (W = 0.95, P < 0.05). Strong and statistically significant correlations were measured between the quantitative results and the reference qualitative histology grades (ρ ≥ 0.75, P < 0.05).

CONCLUSIONS

We have demonstrated that FFOCT is an alternative approach to conventional optical coherence tomography (OCT) that is as well adapted for the qualitative and quantitative assessment of human cartilage as the reference gold standard - histology. This study constitutes the first promising results towards developing a new diagnostic tool in the field of osteoarthritis.

Is arthroscopic videotape a reliable tool for describing early joint tissue pathology of the knee?

BACKGROUND

The aim of this study was to assess the reliability of the videotape scoring system collected during knee arthroscopy for meniscal tears, and to test the consistency with intra-operative findings.

METHODS

Fifty-seven patients undergoing arthroscopic treatment of meniscal tears were included in the analysis. The cartilage damage was assessed intra-operatively, at six sites, using the Outerbridge scoring system. The meniscal tears were graded according to the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) classification. The presence of synovial inflammation was scored, at four different sites, according to the macro-score method. The total cartilage, meniscal and synovial scores were calculated for each knee by the sum of the maximum grade of the lesions at each anatomic site. In order to assess the reliability of the arthroscopic scoring system, the videotapes recorded during the arthroscopy were reviewed by two independent observers one year after the surgery and compared with the scores completed by the surgeon during the operation.

RESULTS

The total cartilage score showed substantial inter-rater and intra-rater reliability, and moderate consistency with the intra-operative score provided by the surgeon. The total meniscal score showed substantial inter-rater and intra-rater reliability, and good consistency with the intra-operative findings. The total synovial score showed substantial inter-rater agreement, substantial intra-rater reliability, and moderate consistency with intra-operative findings.

CONCLUSIONS

The videotape scoring system provided a reliable and reproducible system for recording the intra-operative state of the whole joint pathology in patients undergoing arthroscopic treatment of meniscal tears.

[Chondral and osteochondral defects : Representation by imaging methods]

Morphological imaging of cartilage at high resolution allows the differentiation of chondral and osteochondral lesions. Nowadays, magnetic resonance imaging is the principal diagnostic tool in the assessment of cartilage structure and composition. Conventional radiography, computed tomography, ultrasound or optical coherence tomography are adjunct diagnostic modalities in the assessment of cartilage pathologies. The present article discusses the up-to-date diagnostic practice of cartilage imaging in terms of its scientific basis and current clinical status, requirements, techniques and image interpretation. Innovations in the field such as functional MRI are discussed as well due to their mid- to long-term clinical perspective.

Monitoring osteoarthritis progression using near infrared (NIR) spectroscopy

We demonstrate in this study the potential of near infrared (NIR) spectroscopy as a tool for monitoring progression of cartilage degeneration in an animal model. Osteoarthritic degeneration was artificially induced in one joint in laboratory rats, and the animals were sacrificed at four time points: 1, 2, 4, and 6 weeks (3 animals/week). NIR spectra were acquired from both (injured and intact) knees. Subsequently, the joint samples were subjected to histological evaluation and glycosaminoglycan (GAG) content analysis, to assess disease severity based on the Mankin scoring system and to determine proteoglycan loss, respectively. Multivariate spectral techniques were then employed for classification (principal component analysis and support vector machines) and prediction (partial least squares regression) of the samples’ Mankin scores and GAG content from their NIR spectra. Our results demonstrate that NIR spectroscopy is sensitive to degenerative changes in articular cartilage, and is capable of distinguishing between mild (weeks 1&2; Mankin <=2) and advanced (weeks 4&6; Mankin =>3) cartilage degeneration. In addition, the spectral data contains information that enables estimation of the tissue’s Mankin score (error = 12.6%, R² = 86.2%) and GAG content (error = 7.6%, R² = 95%). We conclude that NIR spectroscopy is a viable tool for assessing cartilage degeneration post-injury, such as, post-traumatic osteoarthritis.

Combination of optical coherence tomography and near infrared spectroscopy enhances determination of articular cartilage composition and structure

Conventional arthroscopic evaluation of articular cartilage is subjective and poorly reproducible. Therefore, implementation of quantitative diagnostic techniques, such as near infrared spectroscopy (NIRS) and optical coherence tomography (OCT), is essential. Locations (n = 44) with various cartilage conditions were selected from mature equine fetlock joints (n = 5). These locations and their surroundings were measured with NIRS and OCT (n = 530). As a reference, cartilage proteoglycan (PG) and collagen contents, and collagen network organization were determined using quantitative microscopy. Additionally, lesion severity visualized in OCT images was graded with an automatic algorithm according to International Cartilage Research Society (ICRS) scoring system. Artificial neural network with variable selection was then employed to predict cartilage composition in the superficial and deep zones from NIRS data, and the performance of two models, generalized (including all samples) and condition-specific models (based on ICRS-grades), was compared. Spectral data correlated significantly (p < 0.002) with PG and collagen contents, and collagen orientation in the superficial and deep zones. The combination of NIRS and OCT provided the most reliable outcome, with condition-specific models having lower prediction errors (9.2%) compared to generalized models (10.4%). Therefore, the results highlight the potential of combining both modalities for comprehensive evaluation of cartilage during arthroscopy.

Development of an Electromechanical Grade to Assess Human Knee Articular Cartilage Quality

Quantitative assessments of articular cartilage function are needed to aid clinical decision making. Our objectives were to develop a new electromechanical grade to assess quantitatively cartilage quality and test its reliability. Electromechanical properties were measured using a hand-held electromechanical probe on 200 human articular surfaces from cadaveric donors and osteoarthritic patients. These data were used to create a reference electromechanical property database and to compare with visual arthroscopic International Cartilage Repair Society (ICRS) grading of cartilage degradation. The effect of patient-specific and location-specific characteristics on electromechanical properties was investigated to construct a continuous and quantitative electromechanical grade analogous to ICRS grade. The reliability of this novel grade was assessed by comparing it with ICRS grades on 37 human articular surfaces. Electromechanical properties were not affected by patient-specific characteristics for each ICRS grade, but were significantly different across the articular surface. Electromechanical properties varied linearly with ICRS grade, leading to a simple linear transformation from one scale to the other. The electromechanical grade correlated strongly with ICRS grade (r = 0.92, p < 0.0001). Additionally, the electromechanical grade detected lesions that were not found visually. This novel grade can assist the surgeon in assessing human knee cartilage by providing a quantitative and reliable grading system.

Interrater and Intrarater Reliability of Arthroscopic Measurements of Articular Cartilage Defects in the Knee

BACKGROUND

Cartilage lesions of the knee are difficult to treat. Lesion size is a critical factor in treatment algorithms, and the accurate, reproducible sizing of lesions is important. In this study, we evaluated the interrater and intrarater reliability of, and correlations in relation to, various arthroscopic sizing techniques.

METHODS

Five lesions were created in each of 10 cadaveric knees (International Cartilage Repair Society grade 3C). Three orthopaedic surgeons used 4 techniques (visualization and use of a 3-mm probe, a simple metal ruler, and a sliding metallic ruler tool) to estimate lesion size. Repeated-measures data were analyzed using a mixed-effect linear model. The differences between observed and gold-standard (plastic mold) values were used as the response. Intraclass and interclass correlation coefficient (ICC) values for intrarater and interrater reliability were computed, as were overall correlation coefficients between measurements and gold standards.

RESULTS

The mean lesion size was 2.37 cm (range, 0.36 to 6.02 cm). Rater, lesion location and size, and measurement method all affected the cartilage defect measurements. Surgeons underestimated lesion size, and measurements of larger lesions had a higher percentage of error compared with those of smaller lesions. When compared with plastic molds of lesions, 60.5% of surgeon measurements underestimated lesion size. Overall, the correlation between measurements and gold standards was strongest for the simple metal ruler method and weakest for the visualization method.

CONCLUSIONS

Several factors may influence arthroscopic estimation of cartilage lesion size: the lesion location, measurement tool, surgeon, and defect size itself. The intrarater and interrater reliability was moderate to good using a 3-mm probe, sliding metallic ruler tool, or simple metal ruler and was fair to moderate using visualization only.

CLINICAL RELEVANCE

There is a need for more accurate methods of determining the size of articular cartilage lesions.

Regular chondrocyte spacing is a potential cause for coherent ultrasound backscatter in human articular cartilage

The potential of quantitative ultrasound (QUS) to assess the regular cellular spacing in the superficial cartilage zones was investigated experimentally and numerically. Nine osteochondral samples, extracted from two human cadaver knee joints, were measured using a 50-MHz ultrasound scanning device and evaluated using Mankin score. Simulated backscattered power spectra from models with an idealized cell alignment exhibited a pronounced frequency peak. From the peak, cell spacing in the range between 15 and 40 μm between cell layers was detected with an average error of 0.2 μm. The mean QUS-based cell spacing was 28.3 ± 5.3 μm. Strong correlation (R²= 0.59, p ≤ 0.001) between spacing estimates from light microscopy (LM) and QUS was found for samples with Mankin score ≤3. For higher scores, QUS-based spacing was significantly higher (p ≤ 0.05) compared to LM-based spacing. QUS-based spacing estimates together with other QUS parameters may serve as future biomarkers for detecting early signs of osteoarthrosis.

Multimodality scoring of chondral injuries in the equine fetlock joint ex vivo

OBJECTIVE

We investigate the potential of a prototype multimodality arthroscope, combining ultrasound, optical coherence tomography (OCT) and arthroscopic indentation device, for assessing cartilage lesions, and compare the reliability of this approach with conventional arthroscopic scoring ex vivo.

DESIGN

Areas of interest (AIs, N = 43) were selected from equine fetlock joints (N = 5). Blind-coded AIs were independently scored by two equine surgeons employing International Cartilage Repair Society (ICRS) scoring system via conventional arthroscope and multimodality arthroscope, in which high-frequency ultrasound and OCT catheters were attached to an arthroscopic indentation device. In addition, cartilage stiffness was measured with the indentation device, and lesions in OCT images scored using custom-made automated software. Measurements and scorings were performed twice in two separate rounds. Finally, the scores were compared to histological ICRS scores.

RESULTS

OCT and arthroscopic examinations showed the highest average agreements (55.2%) between the scoring by surgeons and histology scores, whereas ultrasound had the lowest (50.6%). Average intraobserver agreements of surgeons and interobserver agreements between rounds were, respectively, for conventional arthroscope (68.6%, 69.8%), ultrasound (68.6%, 68.6%), OCT (65.1%, 61.7%) and automated software (65.1%, 59.3%).

CONCLUSIONS

OCT imaging supplemented with the automated software provided the most reliable lesion scoring. However, limited penetration depth of light limits the clinical potential of OCT in assessing human cartilage thickness; thus, the combination of OCT and ultrasound could be optimal for reliable diagnostics. Present findings suggest imaging and quantitatively analyzing the entire articular surface to eliminate surgeon-related variation in the selection of the most severe lesion to be scored.

Risk factors for cartilage damage and osteoarthritis of the elbow joint: case-control study and systematic literature review

INTRODUCTION

This case-control study compares patients with healthy elbows to a group of symptomatic patients with cartilage damage/osteoarthritis.

MATERIALS AND METHODS

The control group (n = 126) was recruited during routine medical examinations of patients (general medical offices). Included in the case group were a total of 92 patients who were undergoing arthroscopy as a result of chronic elbow discomfort. All patients were questioned with regard to occupational stress and athletic stress.

RESULTS

A significantly increased risk of cartilage damage/osteoarthritis was found with subjectively perceived increased stress in occupational settings: OR = 3.8 (95% CI 2.1-6.7); p < 0.001; for the individual stresses of the elbow joint in occupational settings, the following severities in effects were found: Exposure to heavy work OR = 3.9 (95% CI 2.2-6.8); Force OR = 3.7 (95% CI 2.1-6.5); Vibration OR = 4.6 (95% CI 2.5-8.5); Repetition OR = 9.2 (95% CI 3.6-23.3); p < 0.001. Elbow-stressing sport types represent a potential risk factor for the development of cartilage damage/osteoarthritis of the elbow joint: OR = 2.5 (95% CI 1.3-4.7); p = 0.003.

CONCLUSIONS

Cartilage damage/radiographic osteoarthritis of the elbow joint are rare with respect to the overall prevalence of osteoarthritis. In the large number of patients with cartilage damage/radiographic osteoarthritis of the elbow joint, occupational or athletic stress factors and injuries sustained, in addition to other causes (rheumatism, gout), can prove as possible causes of these as secondary to symptomatic forms of osteoarthritis.

Ultrasound palpation for fast in-situ quantification of articular cartilage stiffness, thickness and relaxation capacity

Most current cartilage testing devices require the preparation of excised samples and therefore do not allow intra-operative application for diagnostic purposes. The gold standard during open or arthroscopic surgery is still the subjective perception of manual palpation. This work presents a new diagnostic method of ultrasound palpation (USP) to acquire applied stress and strain data during manual palpation of articular cartilage. With the proposed method, we obtain cartilage thickness and stiffness. Moreover, repeated palpations allow the quantification of relaxation effects. USP measurements on elastomer phantoms demonstrated very good repeatability for both, stage-guided (97.2%) and handheld (96.0%) applications. The USP measurements were compared with conventional indentation experiments and revealed very good agreement on elastomer phantoms ([Formula: see text]) and good agreement on porcine cartilage samples ([Formula: see text]). Artificially degenerated cartilage samples showed reduced stiffness, weak capacity to relax after palpation and an increase of stiffness of approximately 50% with each single palpation. Intact cartilage was measured by USP directly at the patella (in situ) and after excision and removal of the subchondral bone (ex situ), leading to stiffness values of [Formula: see text] and [Formula: see text] ([Formula: see text]), respectively. The results demonstrate the potential of the USP system for cartilage testing, its sensitivity to degenerative changes and as a method for quantifying relaxation processes by means of repeated palpations. Furthermore, the differences in the results of in-situ and ex-situ measurements are of general interest, since such comparison has not been reported previously. We point out the limited comparability of ex-situ cartilage with its in-situ biomechanical behavior.

Preventable Repeat Wrist Arthroscopies: Analysis of the Indications for 133 Cases

Background Frequently, patients undergo repeated wrist arthroscopies for single wrist problems. Purpose The purposes of this study were to assess the indications for repeat wrist arthroscopies and to identify potentially preventable procedures. Methods For this retrospective, two-center study, the electronic patient records were examined for patients, who underwent repeat wrist arthroscopy in a 5-year period. The cases were sorted by the underlying pathologies and the causes that necessitated repeat arthroscopies. Results Ulnar-sided wrist pain accounted for 100 (77%) of all 133 revision arthroscopies: 67 of which due to suspected ulnar triangular fibrocartilage complex (TFCC) avulsions, 33 due to ulnar impaction syndromes. Cartilage was reassessed in 22 (17%) wrists. Thereby, insufficient preoperative diagnostics necessitated pure diagnostic before therapeutic arthroscopy in 49 (37%) wrists: 48 of which for TFCC pathologies, one for a scapholunate (SL) ligament lesion. The uncertainty of diagnosis despite previous arthroscopy necessitated 18 (14%) revision arthroscopies: 15 for ulnar TFCC avulsions, 1 for a central TFCC lesion, 2 to reevaluate the SL ligament. Inadequate photo or video documentation of the cartilage necessitated arthroscopic reassessment in 16 (12%) wrists. Conclusion In this series, two out of three revision arthroscopies could potentially have been prevented. Inadequate preoperative diagnostics with the lack of reliable preoperative diagnoses necessitated pure diagnostic arthroscopies for ulnar-sided wrist pain. However, even arthroscopically, the diagnosis of ulnar TFCC avulsions or SL ligament lesions is not trivial. Surgical skills and experience are necessary to detect such lesions. Finally, adequate photo or video documentation may prevent repeated arthroscopic diagnostic procedures. Level of Evidence Level IV.

In Vivo Evaluation of the Potential of High-Frequency Ultrasound for Arthroscopic Examination of the Shoulder Joint

OBJECTIVE

Accurate arthroscopic evaluation of cartilage lesions could significantly improve the outcome of repair surgery. In this study, we investigated for the first time the potential of intra-articular ultrasound as an arthroscopic tool for grading cartilage defects in the human shoulder joint in vivo and compared the outcome to results from arthroscopic evaluation and magnetic resonance imaging findings.

DESIGN

A total of 26 sites from 9 patients undergoing routine shoulder arthroscopy were quantitatively evaluated with a clinical intravascular (40MHz) ultrasound imaging system, using the regular arthroscopy portals. Reflection coefficient (R), integrated reflection coefficient (IRC), apparent integrated backscattering (AIB), and ultrasound roughness index (URI) were calculated, and high-resolution ultrasound images were obtained per site. Each site was visually graded according to the International Cartilage Repair Society (ICRS) system. "Ultrasound scores" corresponding to the ICRS system were determined from the ultrasound images. Magnetic resonance imaging was conducted and cartilage integrity at each site was classified into 5 grades (0 = normal, 4 = severely abnormal) by a radiologist.

RESULTS

R and IRC were lower at sites with damaged cartilage surface (P = 0.033 and P = 0.043, respectively) and correlated with arthroscopic ICRS grades (r s = -0.444, P = 0.023 and r s = -0.426, P = 0.03, respectively). Arthroscopic ICRS grades and ultrasound scores were significantly correlated (rs = 0.472, P = 0.015), but no significant correlation was found between magnetic resonance imaging data and other parameters.

CONCLUSION

The results suggest that ultrasound arthroscopy could facilitate quantitative clinical appraisal of articular cartilage integrity in the shoulder joint and provide information on cartilage lesion depth and severity for quantitative diagnostics in surgery.

Association between quantitative MRI and ICRS arthroscopic grading of articular cartilage

PURPOSE

To investigate the association of quantitative magnetic resonance imaging (qMRI) parameters with arthroscopic grading of cartilage degeneration. Arthroscopy of the knee is considered to be the gold standard of osteoarthritis diagnostics; however, it is operator-dependent and limited to the evaluation of the articular surface. qMRI provides information on the quality of articular cartilage and its changes even at early stages of a disease.

METHODS

qMRI techniques included T 1 relaxation time, T 2 relaxation time, and delayed gadolinium-enhanced MRI of cartilage mapping at 3 T in ten patients. Due to a lack of generally accepted semiquantitative scoring systems for evaluating severity of cartilage degeneration during arthroscopy, the International Cartilage Repair Society (ICRS) classification system was used to grade the severity of cartilage lesions. qMRI parameters were statistically compared to arthroscopic grading conducted with the ICRS classification system.

RESULTS

qMRI parameters were not linearly related to arthroscopic grading. Spearman's correlation coefficients between qMRI and arthroscopic grading were not significant. The relative differences in qMRI parameters of superficial and deep cartilage varied with degeneration, suggesting different macromolecular alterations in different cartilage zones.

CONCLUSIONS

Results suggest that loss of cartilage and the quality of remaining tissue in the lesion site may not be directly associated with each other. The severity of cartilage degeneration may not be revealed solely by diagnostic arthroscopy, and thus, qMRI can have a role in the investigation of cartilage degeneration.

Near Infrared Spectroscopic Mapping of Functional Properties of Equine Articular Cartilage

Mechanical properties of articular cartilage are vital for normal joint function, which can be severely compromised by injuries. Quantitative characterization of cartilage injuries, and evaluation of cartilage stiffness and thickness by means of conventional arthroscopy is poorly reproducible or impossible. In this study, we demonstrate the potential of near infrared (NIR) spectroscopy for predicting and mapping the functional properties of equine articular cartilage at and around lesion sites. Lesion and non-lesion areas of interests (AI, N = 44) of equine joints (N = 5) were divided into grids and NIR spectra were acquired from all grid points (N = 869). Partial least squares (PLS) regression was used to investigate the correlation between the absorbance spectra and thickness, equilibrium modulus, dynamic modulus, and instantaneous modulus at the grid points of 41 AIs. Subsequently, the developed PLS models were validated with spectral data from the grid points of 3 independent AIs. Significant correlations were obtained between spectral data and cartilage thickness (R ² = 70.3%, p < 0.0001), equilibrium modulus (R ² = 67.8%, p < 0.0001), dynamic modulus (R ² = 68.9%, p < 0.0001) and instantaneous modulus (R ² = 41.8%, p < 0.0001). Relatively low errors were observed in the predicted thickness (5.9%) and instantaneous modulus (9.0%) maps. Thus, if well implemented, NIR spectroscopy could enable arthroscopic evaluation and mapping of cartilage functional properties at and around lesion sites.

The required minimum length of video sequences for obtaining a reliable interobserver diagnosis in wrist arthroscopies

PURPOSE

To examine the relationship between video length for wrist arthroscopy and interobserver reliability.

MATERIALS AND METHODS

100 consecutive wrist arthroscopies were documented by long and short videos of the radiocarpal and the midcarpal joints. The long videos were about twice as long as the short videos. They were presented randomly to two independent and blinded examiners. Their diagnoses were compared to the diagnoses made by the surgeon who performed the arthroscopies. Kappa coefficients were calculated.

RESULTS

Kappa statistics were inconsistent and did not show that the long video provided an obvious advantage over the short video. The Kappa coefficients of the two examiners for the assessment of the cartilage status were 0.524 and 0.700 for the long videos and 0.465 and 0.639 for the short videos, respectively. The examiners diagnosed twice as many false-positive cartilage lesions on short videos than on long videos. The assessment of ligament lesions was more accurate on long than on short videos.

CONCLUSIONS

The results confirmed the hypothesis that the reproducibility of diagnoses based on video documents was influenced by the length of the video sequences. Therefore, it may be advisable for video documentation to be done diligently. The video sequence of the radiocarpal joint should last about 60 s, and that of a midcarpal joint should last about 45 s. Videos of difficult joints should last appropriately longer.

LEVEL OF EVIDENCE

Diagnostic II.

Wavelength-dependent penetration depth of near infrared radiation into cartilage

Articular cartilage is a hyaline cartilage that lines the subchondral bone in the diarthrodial joints. Near infrared (NIR) spectroscopy is emerging as a nondestructive modality for the evaluation of cartilage pathology; however, studies regarding the depth of penetration of NIR radiation into cartilage are lacking. The average thickness of human cartilage is about 1-3 mm, and it becomes even thinner as OA progresses. To ensure that spectral data collected is restricted to the tissue of interest, i.e. cartilage in this case, and not from the underlying subchondral bone, it is necessary to determine the depth of penetration of NIR radiation in different wavelength (frequency) regions. In the current study, we establish how the depth of penetration varies throughout the NIR frequency range (4000-10 000 cm(-1)). NIR spectra were collected from cartilage samples of different thicknesses (0.5 mm to 5 mm) with and without polystyrene placed underneath. A separate NIR spectrum of polystyrene was collected as a reference. It was found that the depth of penetration varied from ∼1 mm to 2 mm in the 4000-5100 cm(-1) range, ∼3 mm in the 5100-7000 cm(-1) range, and ∼5 mm in the 7000-9000 cm(-1) frequency range. These findings suggest that the best NIR region to evaluate cartilage with no subchondral bone contribution is in the range of 4000-7000 cm(-1).

Diagnosis of Knee Osteochondral Lesions With Ultrasound Imaging

Evaluation of articular cartilage and subchondral bone is essential in the diagnosis of joint diseases and injuries. Interobserver and intraobserver reproducibilities of arthroscopic grading are only poor to moderate. Thus, for quantitative and objective evaluation of cartilage and subchondral bone, ultrasound arthroscopy (UA) has been introduced to clarify this dilemma. Assessment of the clinical feasibility of high-frequency ultrasonography (US) during 6 knee arthroscopies was conducted, and the surgical technique is presented. US imaging was conducted with a flexible 9-MHz US catheter inserted into the joint through conventional portals. US and arthroscopy videos were synchronously recorded, and US parameters for cartilage and subchondral bone characteristics were measured. Arthroscopy and US imaging were combined to perform cartilage grading. UA produced quantitative data on lesion size, as well as cartilage quality, and showed subchondral bone changes. Visualization of an osteochondritis dissecans lesion not detected by conventional arthroscopy and US-guided retrograde drilling were possible with UA. To conclude, UA proved to be clinically feasible and aided in the diagnosis when assessing knee osteochondral lesions.

Optical absorption spectra of human articular cartilage correlate with biomechanical properties, histological score and biochemical composition

This study investigates the relationship between the optical response of human articular cartilage in the visible (VIS) and near infrared (NIR) spectral range and its matrix properties.Full-thickness osteochondral cores (dia. = 16 mm, n = 50) were extracted from human cadaver knees (N = 13) at four anatomical locations and divided into quadrants. Absorption spectra were acquired in the spectral range 400-1100 nm from one quadrant. Reference biomechanical, biochemical composition, histological, and cartilage thickness measurements were obtained from two other quadrants. A multivariate statistical technique based on partial least squares (PLS) regression was then employed to investigate the correlation between the absorption spectra and tissue properties.Our results demonstrate that cartilage optical response correlates with its function, composition and morphology, as indicated by the significant relationship between spectral predicted and measured biomechanical (79.0%  ⩽  R(2)  ⩽  80.3%, p  <  0.0001), biochemical (65.1%  ⩽  R(2)  ⩽  81.0%, p  < 0.0001), and histological scores ([Formula: see text] = 83.3%, p  < 0.0001) properties. Significant correlation was also obtained with the non-calcified cartilage thickness ([Formula: see text] = 83.2%, p  <  0.0001).We conclude that optical absorption of human cartilage in the VIS and NIR spectral range correlates with the overall tissue properties, thus providing knowledge that could facilitate development of systems for rapid assessment of tissue integrity.

Evaluation of Single-Impact-Induced Cartilage Degeneration by Optical Coherence Tomography

Posttraumatic osteoarthritis constitutes a major cause of disability in our increasingly elderly population. Unfortunately, current imaging modalities are too insensitive to detect early degenerative changes of this disease. Optical coherence tomography (OCT) is a promising nondestructive imaging technique that allows surface and subsurface imaging of cartilage, at near-histological resolution, and is principally applicable in vivo during arthroscopy. Thirty-four macroscopically normal human cartilage-bone samples obtained from total joint replacements were subjected to standardized single impacts in vitro (range: 0.25 J to 0.98 J). 3D OCT measurements of impact area and adjacent tissue were performed prior to impaction, directly after impaction, and 1, 4, and 8 days later. OCT images were assessed qualitatively (DJD classification) and quantitatively using established parameters (OII, Optical Irregularity Index; OHI, Optical Homogeneity Index; OAI, Optical Attenuation Index) and compared to corresponding histological sections. While OAI and OHI scores were not significantly changed in response to low- or moderate-impact energies, high-impact energies significantly increased mean DJD grades (histology and OCT) and OII scores. In conclusion, OCT-based parameterization and quantification are able to reliably detect loss of cartilage surface integrity after high-energy traumatic insults and hold potential to be used for clinical screening of early osteoarthritis.

Three-dimensional imaging and analysis of human cartilage degeneration using Optical Coherence Tomography

Optical Coherence Tomography (OCT) is an evolving imaging technology allowing non-destructive imaging of cartilage tissue at near-histological resolution. This study investigated the diagnostic value of real time 3-D OCT in comparison to conventional 2-D OCT in the comprehensive grading of human cartilage degeneration. Fifty-three human osteochondral samples were obtained from eight total knee arthroplasties. OCT imaging was performed by either obtaining a single two-dimensional cross-sectional image (2-D OCT) or by collecting 100 consecutive parallel 2-D OCT images to generate a volumetric data set of 8 × 8 mm (3-D OCT). OCT images were assessed qualitatively according to a modified version of the DJD classification and quantitatively by algorithm-based evaluation of surface irregularity, tissue homogeneity, and signal attenuation. Samples were graded according to the Outerbridge classification and statistically analyzed by one-way ANOVA, Kruskal Wallis and Tukey's or Dunn's post-hoc tests. Overall, the generation of 3-D volumetric datasets and their multiple reconstructions such as rendering, surface topography, parametric, and cross-sectional views proved to be of potential diagnostic value. With increasing distance to the mid-sagittal plane and increasing degeneration, score deviations increased, too. In conclusion, 3-D imaging of cartilage with image analysis algorithms adds considerable potential diagnostic value to conventional OCT diagnostics.

Spatial mapping of proteoglycan content in articular cartilage using near-infrared (NIR) spectroscopy

Diagnosis of articular cartilage pathology in the early disease stages using current clinical diagnostic imaging modalities is challenging, particularly because there is often no visible change in the tissue surface and matrix content, such as proteoglycans (PG). In this study, we propose the use of near infrared (NIR) spectroscopy to spatially map PG content in articular cartilage. The relationship between NIR spectra and reference data (PG content) obtained from histology of normal and artificially induced PG-depleted cartilage samples was investigated using principal component (PC) and partial least squares (PLS) regression analyses. Significant correlation was obtained between both data (R(2) = 91.40%, p<0.0001). The resulting correlation was used to predict PG content from spectra acquired from whole joint sample, this was then employed to spatially map this component of cartilage across the intact sample. We conclude that NIR spectroscopy is a feasible tool for evaluating cartilage contents and mapping their distribution across mammalian joint.

Non-destructive electromechanical assessment (Arthro-BST) of human articular cartilage correlates with histological scores and biomechanical properties

OBJECTIVE

The hand-held Arthro-BST™ device is used to map electromechanical properties of articular cartilage. The purpose of the study was to evaluate correlation of electromechanical properties with histological, biochemical and biomechanical properties of cartilage.

METHOD

Electromechanical properties (quantitative parameter (QP)) of eight human distal femurs were mapped manually ex vivo using the Arthro-BST (1 measure/site, 5 s/measure, 3209 sites). Osteochondral cores were then harvested from different areas on the femurs and assessed with the Mankin histological score. Prior to histoprocessing, cores were tested in unconfined compression. A subset of the cores was analyzed with polarized light microscopy (PLM) to assess collagen structure. Biochemical assays were done on additional cores to obtain water content and glycosaminoglycan (GAG) content. The QP corresponding to each core was calculated by averaging all QPs collected within 6 mm of the core center.

RESULTS

The electromechanical QP correlated strongly with both the Mankin score and the PLM score (r = 0.73, P < 0.0001 and r = -0.70, P < 0.0001 respectively) thus accurately reflecting tissue quality and collagen architecture. Electromechanical QP also correlated strongly with biomechanical properties including fibril modulus (r = -0.76, P < 0.0001), matrix modulus (r = -0.69, P < 0.0001), and log of permeability (r = 0.72, P < 0.0001). The QP correlated weakly with GAG per wet weight and with water content (r = -0.50, P < 0.0003 and r = 0.39, P < 0.006 respectively).

CONCLUSION

Non-destructive electromechanical QP measurements correlate strongly with histological scores and biomechanical parameters providing a rapid and reliable assessment of articular cartilage quality.

Differences in injury pattern and prevalence of cartilage lesions in knee and ankle joints: a retrospective cohort study

Osteoarthritis (OA) is more common in the knee compared to the ankle joint. This can not be explained exclusively by anatomical and biomechanical differences. The aim of this study is to analyze and compare the injury pattern (clinically) and the cartilage lesions (arthroscopically) of knee and ankle joints in a cohort of patients from the same catchment area. A retrospective study of the clinical data of 3122 patients (2139 outpatients and 983 inpatients) was performed, who were treated due to an injury of the knee and ankle joint. Statistical analysis was performed using SigmaStat 3.0 (SPSS Inc, Chicago, USA). There is a higher prevalence of injuries in the ankle as compared to the knee joint in this population from the same catchment area. In contrast, high-grade cartilage lesions are more prevalent in the knee, whereas low grade cartilage lesions are equally distributed between knee and ankle. From this data it can be concluded that the frequency of injuries and the injury pattern of knee versus ankle joints do not correlate with the severity of cartilage lesions and may therefore have no direct influence on the differential incidence of OA in those two joints.

Ultrasound arthroscopy of human knee cartilage and subchondral bone in vivo

Arthroscopic ultrasound imaging enables quantitative evaluation of articular cartilage. However, the potential of this technique for evaluation of subchondral bone has not been investigated in vivo. In this study, we address this issue in clinical arthroscopy of the human knee (n = 11) by determining quantitative ultrasound (9 MHz) reflection and backscattering parameters for cartilage and subchondral bone. Furthermore, in each knee, seven anatomical sites were graded using the International Cartilage Repair Society (ICRS) system based on (i) conventional arthroscopy and (ii) ultrasound images acquired in arthroscopy with a miniature transducer. Ultrasound enabled visualization of articular cartilage and subchondral bone. ICRS grades based on ultrasound images were higher (p < 0.05) than those based on conventional arthroscopy. The higher ultrasound-based ICRS grades were expected as ultrasound reveals additional information on, for example, the relative depth of the lesion. In line with previous literature, ultrasound reflection and scattering in cartilage varied significantly (p < 0.05) along the ICRS scale. However, no significant correlation between ultrasound parameters and structure or density of subchondral bone could be demonstrated. To conclude, arthroscopic ultrasound imaging had a significant effect on clinical grading of cartilage, and it was found to provide quantitative information on cartilage. The lack of correlation between the ultrasound parameters and bone properties may be related to lesser bone change or excessive attenuation in overlying cartilage and insufficient power of the applied miniature transducer.

In vivo diagnostics of human knee cartilage lesions using delayed CBCT arthrography

The aim of this study was to investigate the feasibility of delayed cone beam (CBCT) arthrography for clinical diagnostics of knee cartilage lesions. Knee joints with cartilage lesions were imaged using native radiography, MRI, and delayed CBCT arthrography techniques in vivo. The joints were imaged three times with CBCT, just before, immediately after (arthrography) and 45 min after the intra-articular injection of contrast agent. The arthrographic images enabled sensitive detection of the cartilage lesions. Use of arthrographic and delayed images together with their subtraction image enabled also detection of cartilage with inferior integrity. The contrast agent partition in intact cartilage (ICRS grade 0) was lower (p < 0.05) than that of cartilage surrounding the ICRS grade I-IV lesions. Delayed CBCT arthrography provides a novel method for diagnostics of cartilage lesions. Potentially, it can also be used in diagnostics of cartilage degeneration. Due to shorter imaging times, higher resolution, and lower costs of CT over MRI, this technique could provide an alternative for diagnostics of knee pathologies. However, for comprehensive evaluation of the clinical potential of the technique a further clinical study with a large pool of patients having a wide range of cartilage pathologies needs to be conducted.

Application of optical coherence tomography enhances reproducibility of arthroscopic evaluation of equine joints

BACKGROUND

Arthroscopy is widely used in various equine joints for diagnostic and surgical purposes. However, accuracy of defining the extent of cartilage lesions and reproducibility in grading of lesions are not optimal. Therefore, there is a need for new, more quantitative arthroscopic methods. Arthroscopic optical coherence tomography (OCT) imaging is a promising tool introduced for quantitative detection of cartilage degeneration and scoring of the severity of chondral lesions. The aim of this study was to evaluate the inter-investigator agreement and inter-method agreement in grading cartilage lesions by means of conventional arthroscopy and with OCT technique. For this aim, 41 cartilage lesions based on findings in conventional and OCT arthroscopy in 14 equine joints were imaged, blind coded and independently ICRS (International Cartilage Repair Society) scored by three surgeons and one PhD-student.

RESULTS

The intra- and inter-investigator percentages of agreement by means of OCT (68.9% and 43.9%, respectively) were higher than those based on conventional arthroscopic imaging (56.7% and 31.7%, respectively). The intra-investigator Kappa coefficients were 0.709 and 0.565 for OCT and arthroscopy, respectively. Inter-investigator Kappa coefficients were 0.538 and 0.408 for OCT and arthroscopy, respectively.

CONCLUSIONS

OCT can enhance reproducibility of arthroscopic evaluation of equine joints.

Arthroscopic ultrasound technique for simultaneous quantitative assessment of articular cartilage and subchondral bone: an in vitro and in vivo feasibility study

Traditional arthroscopic examination is subjective and poorly reproducible. Recently, we introduced an arthroscopic ultrasound method for quantitative diagnostics of cartilage lesions. Here we describe our investigation of the feasibility of ultrasound arthroscopy for simultaneous measurements of articular cartilage and subchondral bone. Human osteochondral samples (n = 13) were imaged using a clinical 9-MHz ultrasound system. Ultrasound reflection coefficients (R, IRC), the ultrasound roughness index (URI) and the apparent integrated backscattering coefficient (AIB) were determined for both tissues. Mechanical testing, histologic analyses and micro-scale computed tomography imaging were the reference methods. Ultrasound arthroscopies were conducted on two patients. The ultrasound reflection coefficient correlated with the Mankin score and Young's modulus of cartilage (|r| > 0.56, p < 0.05). Ultrasound parameters (R, IRC, AIB) for subchondral bone correlated with the bone surface/volume ratio (|r| > 0.70, p < 0.05) and trabecular thickness (|r| > 0.59, p < 0.05). Furthermore, R and subchondral bone mineral density were significantly correlated (|r| > 0.65, p < 0.05). Arthroscopic ultrasound examination provided diagnostically valuable information on cartilage and subchondral bone in vivo.

Arthroscopic optical coherence tomography provides detailed information on articular cartilage lesions in horses

Arthroscopy enables direct inspection of the articular surface, but provides no information on deeper cartilage layers. Optical coherence tomography (OCT), based on measurement of reflection and backscattering of light, is a diagnostic technique used in cardiovascular surgery and ophthalmology. It provides cross-sectional images at resolutions comparable to that of low-power microscopy. The aim of this study was to determine if OCT is feasible for advanced clinical assessment of lesions in equine articular cartilage during diagnostic arthroscopy. Diagnostic arthroscopy of 36 metacarpophalangeal joints was carried out ex vivo. Of these, 18 joints with varying degrees of cartilage damage were selected, wherein OCT arthroscopy was conducted using an OCT catheter (diameter 0.9 mm) inserted through standard instrument portals. Five sites of interest, occasionally supplemented with other locations where defects were encountered, were arthroscopically graded according to the International Cartilage Repair Society (ICRS) classification system. The same sites were evaluated qualitatively (ICRS classification and morphological description of the lesions) and quantitatively (measurement of cartilage thickness) on OCT images. OCT provided high resolution images of cartilage enabling determination of cartilage thickness. Comparing ICRS grades determined by both arthroscopy and OCT revealed poor agreement. Furthermore, OCT visualised a spectrum of lesions, including cavitation, fibrillation, superficial and deep clefts, erosion, ulceration and fragmentation. In addition, with OCT the arthroscopically inaccessible area between the dorsal MC3 and P1 was reachable in some cases. Arthroscopically-guided OCT provided more detailed and quantitative information on the morphology of articular cartilage lesions than conventional arthroscopy. OCT could therefore improve the diagnostic value of arthroscopy in equine orthopaedic surgery.

The effect of additional video documentation to photo documentation in wrist arthroscopies on intra- and interobserver reliability

INTRODUCTION

The reproducibility of diagnoses based on photo documents in wrist arthroscopies is limited and is expected to improve through the addition of video documents.

AIM

The purpose of this study was to determine the effect of additional video documentation to photo documentation on intra- and interobserver reliability in wrist arthroscopies.

MATERIALS AND METHODS

Sixty consecutive arthroscopies were documented by photographs of at least eight standard views and videos of the radiocarpal and midcarpal joints. After 3 months, the photographs and then the photographs together with the videos were reevaluated by the surgeon and by two hand surgeons to determine intra- and interobserver reliability. Percentage agreement and kappa coefficients were calculated.

RESULTS

Using videos along with the photographs did not improve reproducibility in general. The assessments of the cartilage status were even worse. Some of the videos were criticized as being too short to allow adequate assessment of the cartilage. Lesions of the TFCC as well as its tension were assessed notably better by the videos, whereas assessment of SL and LT ligaments was not improved by the videos. Intraobserver reliability was better than interobserver reliability.

CONCLUSION

As long as videos do not meet further quality criteria, they are not able to improve reliability in general. Nevertheless, videos should be used for documentation of the TFCC.

The effect of labeling photo documents in wrist arthroscopies on intra- and interobserver reliability

INTRODUCTION

The reproducibility of diagnoses based on photo documents in wrist arthroscopies is limited and is expected to improve if the photos are labeled with illustrated structures.

AIM

The purpose of this study was to determine the effect of labeling photo documents on intra- and interobserver agreement and reliability of standard photo documentation in wrist arthroscopies.

MATERIALS AND METHODS

Digital photographs of 50 arthroscopies were re-evaluated by the surgeon as well as by two independent hand surgeons. First the photos were presented unlabeled in a random order, then the labeled photos in a uniform order. Intra- and interobserver reliability was assessed, and expressed by kappa coefficients.

RESULTS

Overall, labeling the photos resulted in a slight improvement in intra- and interobserver reliability (0.573/0.444/0.420 vs. 0.518/0.412/0.212). The time needed to conceive the photo documents, however, was shortened when the photos were labeled. The cartilage status was assessed considerably more accurately if the photos were labeled (0.556/0.560/0.422 vs. 0.459/0.326/0.240; t test: P = 0.094). Whereas the SL ligament was assessed more accurately according to labeled photos (P = 0.100), the agreement rates for the assessment of other ligament structures (TFCC, LT and radiopalmar ligaments) were not substantially affected by labeling the photos. On re-evaluation of the unlabeled as well as the labeled photos, intraobserver reliability was better than interobserver reliability (0.518 vs. 0.412/0.212 and 0.573 vs. 0.444/0.420).

CONCLUSION

Labeling simplifies but does not necessarily improve the reproducibility of photo documents in wrist arthroscopies. To display the cartilage status and the integrity of the SL ligament, digital photo documents should be labeled with the illustrated structure or joint surface.