Preoperative MRI underestimates articular cartilage defect size compared with findings at arthroscopic knee surgery

More negative sagittal tibial tuberosity-trochlear groove distances are correlated with larger patellofemoral chondral lesion size

PURPOSE

The purpose of this study is to assess the association between sagittal tibial tuberosity-trochlear groove (sTT-TG) distance and patellofemoral chondral lesion size in patients undergoing cartilage restoration procedures.

METHODS

A retrospective cohort analysis of patients who underwent an osteochondral allograft transplantation or matrix-induced autologous chondrocyte implantation in the patellofemoral compartment, from 2010 to 2020, were included if they had patellofemoral high-grade lesions, magnetic resonance imaging (MRI) and minimum 2-year follow-up. The preoperative sTT-TG distance was measured independently on axial T2-weighted MRI sequences by two authors, each at least two weeks apart. Intraoperative lesion size was reported according to operative report measurements by the attending surgeon. An interclass correlation coefficient (ICC) was calculated to assess intra- and inter-rater reliability, and categorical data analysis and linear regression models were used to assess the relationship between sTT-TG and lesion size.

RESULTS

A total of 80 patients (50 females) with a mean age of 31.5 ± 10.4 years, body mass index of 27.0 ± 5.9 kg/m2 and follow-up of 61.5 ± 21.4 months were included. A total of 107 lesions were present: 63 patients with unipolar (patella = 41, trochlea = 22) and 22 with bipolar lesions. The mean MRI defect size was 1.6 ± 1.0 cm2 and the mean intraoperative defect size was 3.8 ± 2.4cm2. Intra- (ICC: 0.99,0.98) and inter-rater reliability (ICC: 0.96) were excellent for both MRI defect size and sTT-TG measurements. The mean sTT-TG was -4.8 ± 4.9 mm and was significantly inversely related to MRI defect size (-0.45, p < 0.01), intraoperative patellar lesion size (-0.32, p = 0.01), total lesion area (-0.22, p = 0.04), but not trochlear lesion size (-0.09, p = 0.56). Multivariable regression demonstrated a more negative sTT-TG remained an independent variable correlated with larger MRI-measured patellofemoral defect sizes and intraoperative patellar lesions.

CONCLUSION

A more negative sTT-TG was an independent variable correlated with larger patellofemoral lesions in patients undergoing patellofemoral cartilage restoration.

LEVEL OF EVIDENCE

Level III, Diagnostic.

Higher Accuracy of Arthroscopy Compared to MRI in the Diagnosis of Chondral Lesions in Acute Ankle Fractures: A Prospective Study

Even after successful surgery for acute ankle fractures, many patients continue having complaints. A possible explanation is the presence of concomitant chondral lesions. The aim of this study is to investigate the accuracy of MRI compared to that of arthroscopy in the assessment of chondral lesions in acute ankle fractures. In this prospective single-center study, patients presenting with acute ankle fractures over a period of three years were identified. A preoperative MRI was performed within a maximum of 10 days after trauma. During surgery, ankle arthroscopy was also performed. The International Cartilage Repair Society (ICRS) cartilage lesion classification was used to grade the detected chondral lesions. To localize the chondral lesions, the talar dome was divided into eight zones and the tibial/fibular articular surfaces into three zones. In total, 65 patients (28 females) with a mean age of 41.1 ± 15 years were included. In the MRI scans, 70 chondral lesions were detected (69.2% of patients) affecting mostly the tibial plafond (30%) and mostly graded as ICRS 3. The mean lesion area measured was 20.8 mm2. In the arthroscopy, 85 chondral lesions were detected (70.8% of patients) affecting mostly the medial surface of the talar dome (25.9%) and mostly graded ICRS 3. The mean lesion area measured was 43.4 mm2. The highest agreement between the two methods was observed in the size estimation of the chondral lesions. The present study shows the reduced accuracy of MRI when compared to arthroscopy in the assessment of traumatic chondral lesions in the setting of acute ankle fractures especially regarding lesion size. MRI remains an essential instrument in the evaluation of such lesions; however, surgeons should take this discrepancy into consideration, particularly the underestimation of chondral lesions' size in the preoperative planning of surgical treatment and operative technique.

Development of a patient specific cartilage graft using magnetic resonance imaging and 3D printing

OBJECTIVES

The goal of this project was to develop and validate a patient-specific, anatomically correct graft for cartilage restoration using magnetic resonance imaging (MRI) data and 3-dimensional (3D) printing technology. The specific aim was to test the accuracy of a novel method for 3D printing and implanting individualized, anatomically shaped bio-scaffolds to treat cartilage defects in a human cadaveric model. We hypothesized that an individualized, anatomic 3D-printed scaffold designed from MRI data would provide a more optimal fill for a large cartilage defect compared to a generic flat scaffold.

METHODS

Four focal cartilage defects (FCDs) were created in paired human cadaver knees, age <40 years, in the weight-bearing surfaces of the medial femoral condyle (MFC), lateral femoral condyle (LFC), patella, and trochlea of each knee. MRIs were obtained, anatomic grafts were designed and 3D printed for the left knee as an experimental group, and generic flat grafts for the right knee as a control group. Grafts were implanted into corresponding defects and fixed using tissue adhesive. Repeat post-implant MRIs were obtained. Graft step-off was measured as the distance in mm between the surface of the graft and the native cartilage surface in a direction perpendicular to the subchondral bone. Graft contour was measured as the gap between the undersurface of the graft and the subchondral bone in a direction perpendicular to the joint surface.

RESULTS

Graft step-off was statistically significantly better for the anatomic grafts compared to the generic grafts in the MFC (0.0 ​± ​0.2 ​mm vs. 0.7 ​± ​0.5 ​mm, p ​< ​0.001), LFC (0.1 ​± ​0.3 ​mm vs. 1.0 ​± ​0.2 ​mm, p ​< ​0.001), patella (-0.2 ​± ​0.3 ​mm vs. -1.2 ​± ​0.4 ​mm, p ​< ​0.001), and trochlea (-0.4 ​± ​0.3 vs. 0.4 ​± ​0.7, p ​= ​0.003). Graft contour was statistically significantly better for the anatomic grafts in the LFC (0.0 ​± ​0.0 ​mm vs. 0.2 ​± ​0.4 ​mm, p ​= ​0.022) and trochlea (0.0 ​± ​0.0 ​mm vs. 1.4 ​± ​0.7 ​mm, p ​< ​0.001). The anatomic grafts had an observed maximum step-off of -0.9 ​mm and a maximum contour mismatch of 0.8 ​mm.

CONCLUSION

This study validates a process designed to fabricate anatomically accurate cartilage grafts using MRI and 3D printing technology. Anatomic grafts demonstrated superior fit compared to generic flat grafts.

LEVEL OF EVIDENCE

Level IV.

Evaluation of the consistency of the MRI- based AI segmentation cartilage model using the natural tibial plateau cartilage

OBJECTIVE

The study aims to evaluate the accuracy of an MRI-based artificial intelligence (AI) segmentation cartilage model by comparing it to the natural tibial plateau cartilage.

METHODS

This study included 33 patients (41 knees) with severe knee osteoarthritis scheduled to undergo total knee arthroplasty (TKA). All patients had a thin-section MRI before TKA. Our study is mainly divided into two parts: (i) In order to evaluate the MRI-based AI segmentation cartilage model's 2D accuracy, the natural tibial plateau was used as gold standard. The MRI-based AI segmentation cartilage model and the natural tibial plateau were represented in binary visualization (black and white) simulated photographed images by the application of Simulation Photography Technology. Both simulated photographed images were compared to evaluate the 2D Dice similarity coefficients (DSC). (ii) In order to evaluate the MRI-based AI segmentation cartilage model's 3D accuracy. Hand-crafted cartilage model based on knee CT was established. We used these hand-crafted CT-based knee cartilage model as gold standard to evaluate 2D and 3D consistency of between the MRI-based AI segmentation cartilage model and hand-crafted CT-based cartilage model. 3D registration technology was used for both models. Correlations between the MRI-based AI knee cartilage model and CT-based knee cartilage model were also assessed with the Pearson correlation coefficient.

RESULTS

The AI segmentation cartilage model produced reasonably high two-dimensional DSC. The average 2D DSC between MRI-based AI cartilage model and the tibial plateau cartilage is 0.83. The average 2D DSC between the AI segmentation cartilage model and the CT-based cartilage model is 0.82. As for 3D consistency, the average 3D DSC between MRI-based AI cartilage model and CT-based cartilage model is 0.52. However, the quantification of cartilage segmentation with the AI and CT-based models showed excellent correlation (r = 0.725; P values < 0.05).

CONCLUSION

Our study demonstrated that our MRI-based AI cartilage model can reliably extract morphologic features such as cartilage shape and defect location of the tibial plateau cartilage. This approach could potentially benefit clinical practices such as diagnosing osteoarthritis. However, in terms of cartilage thickness and three-dimensional accuracy, MRI-based AI cartilage model underestimate the actual cartilage volume. The previous AI verification methods may not be completely accurate and should be verified with natural cartilage images. Combining multiple verification methods will improve the accuracy of the AI model.

Proof-of-concept of a robotic-driven photogrammetric scanner for intra-operative knee cartilage repair

This work presents a proof-of-concept of a robotic-driven intra-operative scanner designed for knee cartilage lesion repair, part of a system for direct in vivo bioprinting. The proposed system is based on a photogrammetric pipeline, which reconstructs the cartilage and lesion surfaces from sets of photographs acquired by a robotic-handled endoscope, and produces 3D grafts for further printing path planning. A validation on a synthetic phantom is presented, showing that, despite the cartilage smooth and featureless surface, the current prototype can accurately reconstruct osteochondral lesions and their surroundings with mean error values of 0.199 ± 0.096 mm but with noticeable concentration on areas with poor lighting or low photographic coverage. The system can also accurately generate grafts for bioprinting, although with a slight tendency to underestimate the actual lesion sizes, producing grafts with coverage errors of -12.2 ± 3.7, -7.9 ± 4.9, and -15.2 ± 3.4% for the medio-lateral, antero-posterior, and craneo-caudal directions, respectively. Improvements in lighting and acquisition for enhancing reconstruction accuracy are planned as future work, as well as integration into a complete bioprinting pipeline and validation with ex vivo phantoms.

Quantitative Magnetic Resonance Imaging Had Greater Sensitivity in Diagnosing Chondral Lesions of the Knee: A Systematic Review and Meta-Analysis

PURPOSE

To investigate the accuracy and reliability of magnetic resonance imaging (MRI) in identifying and grading chondral lesions and explore the optimal imaging technique to image cartilage.

METHOD

A comprehensive search was conducted on Medline, Embase, and Cochrane Library. Eligible cohort studies published before August 2022 were included. The study reports used MRI to diagnose and grade cartilage lesions, with intraoperative findings as the reference standard. Summary estimates of diagnostic performance were obtained. The reliability of MRI interpretation was summarized. Subgroup analyses were performed based on assessed imaging techniques, field strength, and joint surface.

RESULTS

Forty-three trials and 3,706 patients were included in the systematic review. The overall area under curve for hierarchical summarized receiver operating characteristics was 0.91 (95% confidence interval [CI] 0.88-0.93). The pooled sensitivity for quantitative MRI, 3-dimensional MRI, and 2-dimensional MRI was 0.82 (95% CI 0.64-0.92), 0.79 (95% CI 0.74-0.83), and 0.63 (95% CI 0.51-0.73), respectively. The pooled sensitivity of 3 Tesla (3T), 1.5 Tesla (1.5T), and <1.5 Tesla MRI was 0.79 (95% CI 0.72-0.85), 0.67 (95% CI 0.60-0.74), and 0.55 (95% CI 0.39-0.71), respectively. There were differences in interobserver consistency across different studies.

CONCLUSIONS

In general, MRI had high specificity in discriminating normal cartilage, but its sensitivity for identifying chondral lesions is less optimal. Further analysis showed that quantitative MRI, 3D MRI, and 3T MRI demonstrate greater sensitivity compared with 2D MRI, 1.5T MRI, and <1.5 Tesla MRI.

LEVEL OF EVIDENCE

Level III, systematic review of Level II-III studies.

Quantification of Synovial Fluid Using Magnetic Resonance Fingerprinting Multicomponent Imaging in the Articular Cartilage of the Knee

RATIONALE AND OBJECTIVES

The purpose of this study was to verify the feasibility of magnetic resonance fingerprinting (MRF)-derived synovial fluid fraction (SFF) mapping for quantifying subvoxel-sized cartilage defects.

MATERIALS AND METHODS

MRF was performed on a 3-Tesla scanner and used to derive T2 and SFF maps. An ex vivo experiment was performed using bovine bone; different numbers of holes (4, 6, 8, 10, and 12) were drilled separately on the articular surface, and SFF values were compared among the drilled areas. In a clinical study, 16 osteoarthritis patients underwent sagittal 3D fast spinecho (FSE) and MRF scanning, and knee cartilage segmentation was performed on each image. For morphologic analysis, fluid-excluded images of the SFF (FEISFF) and T2 maps (FEIT2) were generated using the cartilage segmentations, and the whole-organ magnetic resonance imaging score (WORMS) of each FEI and 3D FSE image were compared using the kappa coefficient. For quantitative analysis, intact cartilage volumes in the SFF (VSFF) and T2 maps (VT2) were calculated, and their correlations with reference to the actual cartilage volume on 3D FSE images (V3D) were evaluated.

RESULTS

In the ex vivo experiment, the SFF value increased as the number of holes increased. The kappa coefficients of the WORMS were 0.80 and 0.64 in the SFF and T2 maps, respectively, and substantial to almost perfect agreement was observed in the medial tibiofemoral joint. The V3D-VSFF and V3D-VT2 correlation coefficients differed by 0.03 or more in the medial tibiofemoral joint.

CONCLUSION

The MRF-derived SFF map can feasibly evaluate small, invisible cartilage defects and quantify cartilage volumes.

Comparison of Knee Articular Cartilage Defect Size Between Measurements Obtained on Preoperative MRI Versus During Arthrotomy

Background

Treatment decisions for cartilage defects are often based on lesion size. Magnetic resonance imaging (MRI) is widely used to diagnose cartilage defects noninvasively; however, their size estimated from MRI may differ from defect sizes measured during arthrotomy, especially after debridement to healthy cartilage if undergoing autologous chondrocyte implantation.

Purpose/Hypothesis

The purpose of this study was to evaluate the reliability of 2 methods to assess knee cartilage defect size on preoperative MRI and determine their accuracy in predicting postdebridement defect sizes recorded during arthrotomy. It was hypothesized that defect size would be predicted more accurately by the total area of abnormal articular cartilage rather than the area of full-thickness cartilage loss as identified on MRI.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Methods

This study included 64 patients (mean age, 41.8 ± 9.6 years) who underwent autologous cell therapy. Each patient received a 3-T MRI at 6.1 ± 3.0 weeks before cell implantation. Three raters, a radiologist, a surgeon, and a scientist, measured (1) the full-thickness cartilage defect area and (2) the total predicted abnormal cartilage area, identified by an abnormal signal on MRI. Interrater reliability was assessed using the intraclass correlation coefficient (ICC). Actual pre- and postdebridement defect sizes were obtained from intraoperative surgical notes. Postdebridement surgical measurements were considered the clinical reference standard and were compared with the radiologist's MRI measurements.

Results

Eighty-seven defects were assessed, located on the lateral (n = 8) and medial (n = 26) femoral condyle, trochlea (n = 17), and patella (n = 36). The interrater reliability of the cartilage defect measurements on MRI was good to excellent for the full-thickness cartilage defect area (ICC = 0.74) and the total predicted abnormal cartilage area (ICC = 0.78). The median full-thickness cartilage defect area on MRI underestimated the median postdebridement defect area by 78.3%, whereas the total predicted abnormal cartilage area measurement underestimated the postdebridement defect area by 14.3%.

Conclusion

Measuring the full-thickness cartilage defect area on MRI underestimated the area to treat, whereas measuring the total abnormal area provided a better estimate of the actual defect size for treatment.

Arthroscopic Treatment of Femoral Condyle Chondral Lesions: Microfracture Versus Liquid Bioscaffold

Purpose

This study aims to compare the microfracture (MF) technique with the bioscaffold solution application (BST-CarGel) in treating femoral chondral lesions.

Methods

Thirty-eight patients ages 18-45 with isolated single femoral condyle full-thickness (ICRS grade 3-4) chondral lesions were included in the study. Patients were divided into two groups as MF applied (Group I = 21) and bioscaffold combined with MF (Group II = 17). The visual analog scale (VAS), Western-Ontario, and McMaster Osteoarthritis Index (WOMAC) were used in clinical evaluation. The location, size, and depth of lesions were evaluated with preoperative magnetic resonance imaging (MRI). Magnetic resonance observation of cartilage repair tissue (MOCART) score was used for postoperative evaluation.

Results

The mean age was 32.5 (range 19-44) years. Mean follow-up was 14.9 months (range 12-24). Lesion size was 3 cm2 in group I and 2.9 cm2 in group II. There were no differences between groups regarding demographic characteristics but BMI (Body Mass Index) was lower in group II which was significant. The duration of surgery was longer in group II (p < 0.001). Postoperative statistical significant improvements were found in WOMAC and VAS scores in groups, but there was no statistical difference. Although there was no significant radiological difference in the group II according to the MOCART score, higher scores were obtained compared to group I.

Conclusion

No difference was found, clinical and radiological, in terms of short-term outcomes. MF is a method to be applied as a primary treatment with its cost-effective, simple and short surgery technique, and effective clinical results up to 4 cm2.

Level of Evidence

Level III: retrospective comparative study.

Preoperative diagnosis of knee cartilage, meniscal, and ligament injuries by magnetic resonance imaging

PURPOSE

The purpose of the study was to report on the current accuracy measures specific to 1.5-Tesla MRI of the knee in the patient population prone to injuries of the anterior cruciate ligament (ACL), the menisci, and the articular cartilage.

METHODS

We accrued patients between January 2018 through August 2021 who underwent a preoperative MRI and were diagnosed with an articular cartilage injury either due to unevenness of articular cartilage in T2-weighted sequences or due to the irregularity of subchondral bone in T1-weighted sequences. All patients were treated arthroscopically. Sensitivity, specificity, and accuracy were calculated for the detection of ACL, meniscus, and cartilage injuries. A P-value of < 0.05 represented statistical significance.

RESULTS

One-hundred and forty-seven cases which included 150 knee joints were enrolled in this study. The mean age at the time of surgery was 42.9 years-old. The sensitivity in the diagnosis of ACL injuries was significantly greater than that in the diagnosis of cartilage injuries (P = 0.0083). The ratios of the equality of operative indication in 6 recipient sites were found to be between 90.0% and 96.0%. The diagnostic critical point was within a 1 cm in diameter.

CONCLUSION

The diagnostic sensitivity in cartilage injuries was significantly lower than ones of ACL and meniscal injuries. The ratios of the equality of operative indication was determined to be between 90.0% and 96.0%, if we consider the unevenness of articular cartilage or the irregularity of subchondral bone.

LEVEL OF EVIDENCE

Level III, Prospective diagnostic cohort study.

Moving orthopaedic procedures out of the operating theatre:Outpatient needle arthroscopy can reduce cost & waste, and increase inpatient capacity compared to conventional knee arthroscopy

BACKGROUND

Needle arthroscopy (NA) is an emerging technique that could streamline pathways, facilitate timely care, and reduce service burden. The primary aim was to assess the practical and economic viability of an outpatient NA service. Secondary aims were to assess the relative costs and benefits compared to a conventional arthroscopy (CA) service.

METHODS

This service feasibility study was conducted between 2021-2022 in a high-volume national treatment centre. A NA pathway was established for patients with chronic soft tissue pathology or early degenerative knee disease. The pathway was evaluated in terms of: i) cost; ii) efficiency, and iii) waste production, and an assessment was conducted of the patient-related and service-related effects.

RESULTS

The cost of the NA pathway was £1555.20 per patient, compared to £2,351.53 for CA. Time to management was 45 days for NA versus 180 days for CA. The NA pathway involved two hospital attendances, whereas CA required a minimum of three. NA cases produced 1.4 kg of non-recyclable waste compared to 5.0 kg produced by CA. For every two cases managed by NA instead of CA, capacity for one additional obligate-inpatient procedure was created.

CONCLUSIONS

The NA pathway offers a technically and economically viable approach for the management of refractory knee symptoms in the context of chronic soft tissue or early degenerative disease. NA placed less demand on hospital resources, produced two-thirds less non-recyclable waste, and is amenable to a one-stop clinic approach. Clinical studies focused on objective and patient-reported outcome measures are required to assess clinical efficacy.

Application of 3D Modeling Software to Preoperative MRI for Prediction of Surface Area of Tissue Applied During Osteochondral Allograft Reconstruction of the Knee

Background

Preoperative magnetic resonance imaging (MRI) is used to estimate the quantity of tissue provided for fresh osteochondral allograft (FOCA) in the knee. Use of 3-dimensional (3D) MRI modeling software for this purpose may improve defect assessment, providing a more accurate estimate of osteochondral allograft tissue required and eliminating the possibility of acquiring an inadequate quantity of tissue for transplant surgery.

Purpose

To evaluate the capacity of damage assessment (DA) 3D MRI modeling software to preoperatively estimate the osteochondral allograft surface area used in surgery.

Study Design

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

Methods

Included were 36 patients who had undergone FOCA surgery to the distal femur. Based on the preoperative MRI scans, the DA software estimated the total surface area of the lesion as well as the surface areas of each subarea of injury: full-thickness cartilage injury (International Cartilage Repair Society [ICRS] grade 4), partial-thickness cartilage injury (ICRS grade 2-3), bone marrow edema, bone loss, and bone cyst. The probability of overestimation of graft tissue areas by the DA software was calculated using a Bayes-moderated proportion, and the relationship between the prediction discrepancy (ie, over- or underestimation) and the magnitude of the DA estimate was assessed using nonparametric local-linear regression.

Results

The DA total surface area measurement overestimated the actual area of FOCA tissue transplanted 81.6% (95% CI, 67.2%-91.4%) of the time, corresponding to a median overestimation of 3.14 cm², or 1.78 times the area of FOCA transplanted. The DA software overestimated the area of FOCA transplanted 100% of the time for defect areas measuring >4.52 cm². For defects <4.21 cm², the maximum-magnitude underestimation of tissue area was 1.45 cm² (on a fold scale, 0.63 times the transplanted area); a plausible heuristic is that multiplying small DA-measured areas of injury by a factor of ∼1.5 would yield an overestimation of the tissue area transplanted most of the time.

Conclusion

The DA 3D modeling software overestimated osteochondral defect size >80% of the time in 36 distal femoral FOCA cases. A policy of consistent but limited overestimation of osteochondral defect size may provide a more reliable basis for predicting the minimum safe amount of allograft tissue to acquire for transplantation.

Artificial-Intelligence-Aided Radiographic Diagnostic of Knee Osteoarthritis Leads to a Higher Association of Clinical Findings with Diagnostic Ratings

BACKGROUND

Radiographic knee osteoarthritis (OA) severity and clinical severity are often dissociated. Artificial intelligence (AI) aid was shown to increase inter-rater reliability in radiographic OA diagnosis. Thus, AI-aided radiographic diagnoses were compared against AI-unaided diagnoses with regard to their correlations with clinical severity.

METHODS

Seventy-one DICOMs (m/f = 27:42, mean age: 27.86 ± 6.5) (X-ray format) were used for AI analysis (KOALA software, IB Lab GmbH). Subjects were recruited from a physiotherapy trial (MLKOA). At baseline, each subject received (i) a knee X-ray and (ii) an assessment of five main scores (Tegner Scale (TAS); Knee Injury and Osteoarthritis Outcome Score (KOOS); International Physical Activity Questionnaire; Star Excursion Balance Test; Six-Minute Walk Test). Clinical assessments were repeated three times (weeks 6, 12 and 24). Three physicians analyzed the presented X-rays both with and without AI via KL grading. Analyses of the (i) inter-rater reliability (IRR) and (ii) Spearman's Correlation Test for the overall KL score for each individual rater with clinical score were performed.

RESULTS

We found that AI-aided diagnostic ratings had a higher association with the overall KL score and the KOOS. The amount of improvement due to AI depended on the individual rater.

CONCLUSION

AI-guided systems can improve the ratings of knee radiographs and show a stronger association with clinical severity. These results were shown to be influenced by individual readers. Thus, AI training amongst physicians might need to be increased. KL might be insufficient as a single tool for knee OA diagnosis.

Typical Complications After Cartilage Repair of the Ankle Using Autologous Matrix-Induced Chondrogenesis (AMIC)

Background:

Autologous matrix-induced chondrogenesis (AMIC) for the treatment of osteochondral lesions of the talus (OLT) results in favorable clinical outcomes, yet high reoperation rates. The aim of this study was to report and analyze typical complications and their risk factors after AMIC for OLT.

Methods:

A total of 127 consecutive patients with 130 AMIC procedures for OLT were retrospectively assessed. All AMIC procedures were performed in an open fashion with 106 (81.5%) cases requiring a malleolar osteotomy (OT) to access the OLT. Seventy-one patients (54.6%) underwent subsequent surgery. These cases were evaluated at a mean follow-up of 3.1 years (±2.5) for complications reviewing postoperative imaging and intraoperative findings during revision surgery. Six patients (8.5%) were lost to follow-up. Regression model analysis was conducted to identify factors that were associated with AMIC-related complications.

Results:

Among the 65 (50%) patients who required revision surgery, 18 patients (28%) demonstrated AMIC-related complications with deep fissuring (83%) and thinning (17%) of the AMIC graft. Conversely, 47 patients (72%) underwent subsequent surgery due to AMIC-unrelated reasons including isolated removal of symptomatic hardware (n = 17) and surgery addressing concomitant pathologies with (n = 25) and without hardware removal (n = 5). Previous prior cartilage repair surgery was significantly associated with AMIC graft-associated complications in patients undergoing revision surgery ( P = .0023). Among age, body mass index, defect size, smoking, and bone grafting, smoking was the only factor showing statistical significance with an odds ratio of 3.7 (95% CI 1.24, 10.9; P = .019) to undergo revision surgery due to graft-related complications, when adjusted for previous cartilage repair surgery.

Conclusion:

The majority of revision surgeries after AMIC for OLT are unrelated to the performed AMIC graft but frequently address symptomatic hardware and concomitant pathologies. Both smoking and previous cartilage repair surgery seem to significantly increase the risk of undergoing revision surgery due to AMIC-related complications.

Level of evidence:

Level IV, case series.

Time Matters: Knee Cartilage Defect Expansion and High-Grade Lesion Formation while Awaiting Autologous Chondrocyte Implantation

OBJECTIVE

The objective of this study was to assess potential risk factors, including time delay until implantation, for knee cartilage defect expansion or new high-grade defect formation between biopsy and Autologous Chondrocyte Implantation (ACI) or Matrix Autologous Chondrocyte Implantation (MACI).

STUDY DESIGN

Consecutive knee ACI and MACI cases by a single surgeon (n = 111) were reviewed. The relationship between time between biopsy and staged implantation and (1) progression in primary cartilage defect size and (2) development of a new high-grade (Outerbridge grade ≥3) cartilage defect were determined with adjustment for demographics, body mass index, smoking status, coronal alignment, initial cartilage status, and prior surgery.

RESULTS

Average size of the primary defect at time of biopsy was 4.50 cm². Mean time to chondrocyte implantation was 155 days. Defect expansion increased 0.11 cm² (standard error = 0.03) per month delay to implantation (P = 0.001). Independent predictors of defect expansion were male sex, smaller initial defect size, and delay to implantation (adjusted mean = 0.15 cm² expansion per month). A total of 16.2% of patients (n = 18/111) developed a new high-grade defect. Independent predictors of a new secondary defect were Outerbridge grade 2 changes (vs. 0-1) on the surface opposing the index defect and delayed implantation (per month increase, adjusted odds ratio = 1.21, 95% confidence interval: 1.01-1.44; P = 0.036).

CONCLUSIONS

Patients undergoing 2-stage cell-based cartilage restoration with either ACI or MACI demonstrated long delays between stages of surgery, placing them at risk for expanding defects and development of new high-grade cartilage defects. Patients who were male, had smaller initial defect size, and longer time between surgeries were at greater risk for defect expansion.

LEVEL OF EVIDENCE

III, retrospective comparative study.

Symptom Chronicity and Tobacco Use: Differences in Athletic and Nonathletic Candidates for Cartilage Surgery

OBJECTIVE

To determine whether there are differences in symptomatic knee cartilage defects and rates of tobacco use among age-matched athletes versus nonathletes undergoing initial arthroscopic knee surgery who meet demographic and radiographic criteria for cartilage restoration surgery.

DESIGN

Age-matched athletes (n = 186) and nonathletes (n = 159) age 40 or less with a body mass index (BMI) of 35 kg/m² or less (mean 26.8 SD 4.1) and <50% joint space narrowing on weight-bearing radiographs were included. All patients had a symptomatic Outerbridge grade 2 or higher cartilage defect visualized during knee arthroscopy. Relationship between athletic status and chronicity of knee symptoms prior to surgery and tobacco use status, cartilage defect Outerbridge grade, size, and location at time of surgery were characterized.

RESULTS

Nonathletes were more likely to smoke (P < 0.001) and had higher BMI (P = 0.005). Duration of symptoms prior to surgery was shorter among athletes (P < 0.001). Grade 4 defects were equally prevalent (P = 0.96) as were multicompartment grade 3-4 lesions (P = 0.12). Mean grade 3-4 defect size was similar in lateral (P = 0.96) and medial compartments (P = 0.82). There was a trend toward larger anterior compartment defects in nonathletes (P = 0.07).

CONCLUSIONS

Among age-matched athletes and nonathletes with symptomatic cartilage defects who meet demographic criteria for cartilage restoration, nonathletes were more likely to smoke and have a longer duration of symptoms prior to treatment. Athletes tended to present earlier but with similar size defects compared to nonathletes, supporting accelerated treatment of defects in athletes and caution toward allowing continued athletic participation in patients with known cartilage defects.

High resolution flat-panel CT arthrography vs. MR arthrography of artificially created osteochondral defects in ex vivo upper ankle joints

PURPOSE

High resolution flat-panel computed tomography arthrography (FPCT-A) and magnetic resonance arthrography (MR-A) are well suited to evaluate osteochondral lesions. The current study compares the performance of FPCT-A versus MR-A in an experimental setting.

METHODS

Fourteen cadaveric ankles were prepared with artificial osteochondral defects of various sizes in four separate talar locations. After intra-articular contrast injection, FPCT-A and 3-T MR-A were acquired. Each defect was then filled with synthetic pallets. The resulting cast was used as reference. Two independent radiologists measured the dimensions of all defects with FPCT-A and MR-A. Intra-class correlation coefficients (ICC) were calculated. Data were compared using t-tests and Bland-Altman plots.

RESULTS

The correlation for FPCT-A and cast was higher compared to MR-A and cast (ICC 0.876 vs. 0.799 for surface [length x width]; ICC 0.887 vs. 0.866 for depth, p<0.001). Mean differences between FPCT-A and cast measurements were -1.1 mm for length (p<0.001), -0.7 mm for width (p<0.001) and -0.4 mm for depth (p = 0.023). By MR-A, there were no significant differences for length and width compared to cast (p>0.05). Depth measurements were significantly smaller by MR-A (mean difference -1.1 mm, p<0.001). There was no bias between the different modalities.

CONCLUSIONS

Ex vivo FPCT-A and MR-A both deliver high diagnostic accuracy for the evaluation of osteochondral defects. FPCT-A was slightly more accurate than MR-A, which was most significant when measuring lesion depth.

Ultrasound-guided diagnostic IPACK as a valuable tool in the management of a patient with soleal sling syndrome: a doubly rare case report

This article describes the use of an infiltration between the popliteal artery and capsule of the knee joint (IPACK) to diagnose an entrapment neuropathy of the tibial nerve (TN) in a patient presenting with chronic neuropathic pain in the medial posterior compartment of the left knee, with a previous electromyography showing no evidence of tibial or common peroneal nerve neuropathy. After a positive sciatic nerve block, the patient was evaluated for a TN block, cancelled due to the presence of an abnormal leash of vessels wrapping around the nerve. For this reason, the patient was submitted to a diagnostic IPACK. A negative IPACK suggested that a compression of the TN at the popliteal fossa was the most likely source of the symptoms. After surgical decompression of the TN nerve at the popliteal fossa, the patient's symptoms decreased substantially.

Accurate Reporting of Concomitant Procedures Is Highly Variable in Studies Investigating Knee Cartilage Restoration

OBJECTIVE

Successful clinical outcomes following cartilage restoration procedures are highly dependent on addressing concomitant pathology. The purpose of this study was to document methods for evaluating concomitant procedures of the knee when performed with articular cartilage restoration techniques, and to review their reported findings in high-impact clinical orthopedic studies. We hypothesized that there are substantial inconsistencies in reporting clinical outcomes associated with concomitant procedures relative to outcomes related to isolated cartilage repair.

DESIGN

A total of 133 clinical studies on articular cartilage repair of the knee were identified from 6 high-impact orthopedic journals between 2011 and 2017. Studies were included if they were primary research articles reporting clinical outcomes data following surgical treatment of articular cartilage lesions with a minimum sample size of 5 patients. Studies were excluded if they were review articles, meta-analyses, and articles reporting only nonclinical outcomes (e.g., imaging, histology). A full-text review was then used to evaluate details regarding study methodology and reporting on the following variables: primary cartilage repair procedure, and the utilization of concomitant procedures to address additional patient comorbidities, including malalignment, meniscus pathology, and ligamentous instability. Each study was additionally reviewed to document variation in clinical outcomes reporting in patients that had these comorbidities addressed at the time of surgery.

RESULTS

All studies reported on the type of primary cartilage repair procedure, with autologous chondrocyte implantation (ACI) noted in 43% of studies, microfracture (MF) reported in 16.5%, osteochondral allograft (OCA) in 15%, and osteochondral autograft transplant (OAT) in 8.2%. Regarding concomitant pathology, anterior cruciate ligament (ACL) reconstruction (24.8%) and meniscus repair (23.3%) were the most commonly addressed patient comorbidities. A total of 56 studies (42.1%) excluded patients with malalignment, meniscus injury, and ligamentous instability. For studies that addressed concomitant pathology, 72.7% reported clinical outcomes separately from the cohort treated with only cartilage repair. A total of 16.5% of studies neither excluded nor addressed concomitant pathologies. There was a significant amount of variation in the patient reported outcome scores used among the studies, with the majority of studies reporting International Knee Documentation Committee (IKDC) and Knee Injury and Osteoarthritis Outcomes Score (KOOS) in 47.2% and 43.6% of articles, respectively.

CONCLUSIONS

In this study on knee cartilage restoration, recognition and management of concomitant pathology is inadequately reported in approximately 28% of studies. Only 30% of articles reported adequate treatment of concomitant ailments while scoring their outcomes using one of a potential 18 different scoring systems. These findings highlight the need for more standardized methods to be applied in future research with regard to inclusion, exclusion, and scoring concomitant pathologies with regard to treatment of cartilage defects in the knee.

Knee Cartilage Defect Characteristics Vary among Symptomatic Recreational and Competitive Scholastic Athletes Eligible for Cartilage Restoration Surgery

OBJECTIVE

To determine whether there are differences by sport or competitive level in symptomatic knee cartilage defects among recreational, high school, or collegiate competitive athletes undergoing initial arthroscopic knee surgery who meet criteria for cartilage restoration surgery.

DESIGN

Three hundred recreational (n = 172) and high school or collegiate competitive athletes (n = 128) younger than 40 years and body mass index (BMI) <35 kg/m² (63% male, mean age 24.3 years, SD 7.1; mean BMI 25.7 kg/m², SD 3.7) with Outerbridge grade 2 or higher symptomatic cartilage defects who underwent arthroscopic knee surgery were identified. The independent relationship between sporting activity or competitive level and cartilage defect location, size, severity, and symptom chronicity were assessed by multivariate regression analysis.

RESULTS

Full-thickness defects were present in 24% of competitive athletes and 31% of recreational athletes (P = 0.21). There was a trend toward an independent association with competitive level and high-grade (3 or 4) multicompartment disease (adjusted odds ratio [aOR] 3.99, 95% confidence interval 0.84-18.8; P = 0.08) or isolated anterior compartment defects (aOR 2.00, 95% CI 0.86-4.62, P = 0.10) but not isolated medial or lateral defects. High-grade defect size was similar among recreational and competitive athletes (P = 0.71). High-grade lateral defect prevalence differed by sport (running 24%, basketball 23%, soccer 18%, football 5%; P = 0.02) but not medial or anterior defect prevalence.

CONCLUSIONS

Among recreational and high school or collegiate competitive athletes with symptomatic cartilage defects who meet criteria for cartilage restoration, competitive athletes may have higher risk of high-grade anterior and multicompartment defects but no difference in defect size.

Cartiform Implantation for focal cartilage defects in the knee: A 2-year clinical and magnetic resonance imaging follow-up study

The purpose of this study was to evaluate clinical and magnetic resonance imaging (MRI) outcomes in patients who underwent cryopreserved viable osteochondral allograft (CVOCA) implantation for focal cartilage defects in the knee at a minimum of 2-years postoperatively. This is a retrospective follow-up study of twelve patients who underwent CVOCA implantation from 2013 to 2015 by a single surgeon for a International Cartilage Repair Society (ICRS) grade 3 or 4 chondral defect. Patient-reported outcome (PRO) measurements and MRI were obtained 2-years postoperatively. Collected PRO measures included: International Knee Documentation Committee (IKDC) form; Visual Analog Scale (VAS) pain score; Veterans RAND 12-Item Health Survey (VR-12); Knee Injury and Osteoarthritis Outcome Score (KOOS); and Western Ontario McMaster Universities Osteoarthritis Index (WOMAC). Patients completed a standard return to work and sports/recreation survey. A blinded, fellowship-trained musculoskeletal radiologist independently evaluated each MRI to determine the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score. Mean follow-up was 2.1 years (2.0-2.3). There were 6 women and 6 men with a mean age of 46.2 ± 11.9 years. Mean PRO scores were: IKDC 72.6 ± 17.4; VAS 2.9 ± 2.8; WOMAC 84.2 ± 15.1; KOOS- Pain 83.8 ± 18.5, Symptoms 77.6 ± 16.0, ADL 88.0 ± 16.9, Sports/Rec 67.7 ± 33.3, QOL 54.8 ± 24.2; and VR-12 PCS 45.0 ± 8.5 and MCS 51.1 ± 9.5. The mean MOCART score was 59.5 ± 12.9. To our knowledge, this is the largest study to report clinical and MRI outcomes of CVOCA implantation in the knee. With positive functional outcomes and lack of failures at 2-year follow-up, CVOCA is a promising treatment option for focal chondral defects in the knee.

STUDY DESIGN

Retrospective case series, Level of evidence 4.

Large chondral defect not covered by meniscal allograft is associated with inferior graft survivorship after lateral meniscal allograft transplantation

PURPOSE

This study aimed to evaluate graft survivorship according to the size and location of chondral defects and its effect on clinical outcomes after meniscal allograft transplantation (MAT). It was hypothesized that large chondral defects would be associated with inferior outcomes.

METHODS

Patients who underwent lateral MAT with fresh-frozen allografts between 2007 and 2016 were retrospectively reviewed. The inclusion criteria were patients with femoral or tibial chondral defects (International Cartilage Repair Society grade 4) who were followed up more than 2 years with 3.0-T magnetic resonance imaging (MRI) scans. Maximal lesion diameter and location were assessed on MRI. The patients were divided into two groups, with chondral defects of < 3 and ≥ 3 cm² on the tibial side. Graft survivorship was compared between the two groups. Graft failure was defined as revisional MAT, meniscal tear or meniscectomy greater than one-third of the allograft on MRI. Clinical outcomes were evaluated using the modified Lysholm score.

RESULTS

Twenty-eight knees in 26 patients (mean age 37.4 ± 10.3 years) with a mean follow-up of 3.6 ± 1.0 (range 2.0-5.4) years were identified. Nineteen knees in 17 patients had both femoral and tibial chondral defects, 7 knees in 7 patients had only femoral chondral defects, and 2 knees in 2 patients had only tibial chondral defects. The mean preoperative femoral and tibial chondral defect sizes were 1.7 ± 1.2 and 3.0 ± 1.4 cm², respectively. Among the seven graft failures, no graft failure occurred in the cases with tibial chondral defects of < 3 cm². Tibial chondral defects of ≥ 3 cm² were significantly associated with graft failure (P = 0.004; odds ratio 28.3; 95% confidence interval 2.5-4006.7). Defects of < 3 cm² were located primarily in the posterior aspect of the lateral tibial plateau, and most lesions were covered by allograft (7/9, 77.8%). The modified Lysholm scores significantly improved irrespective of chondral defects size (P < 0.001).

CONCLUSIONS

Larger chondral defects, more than 3 cm² on the tibial side, were associated with inferior graft survivorship but did not influence the clinical outcomes after MAT at the 3.6-year follow-up. Chondral defect location was associated with defect size.

LEVEL OF EVIDENCE

IV.

Management of Large Focal Chondral and Osteochondral Defects in the Knee

Large, focal articular cartilage defects of the knee (> 4 cm²) can be a source of significant morbidity and often require surgical intervention. Patient- and lesion-specific factors must be identified when evaluating a patient with an articular cartilage defect. In the management of large cartilage defects, the two classically utilized cartilage restoration procedures are osteochondral allograft (OCA) transplantation and cell therapy, or autologous chondrocyte implantation (ACI). Alternative techniques that are available or currently in clinical trials include a hyaluronan-based scaffold plus bone marrow aspirate concentrate, a third-generation autologous chondrocyte implant, and an aragonite-based scaffold. In this review, we will focus on OCA and ACI as the mainstay in management of large chondral and osteochondral defects of the knee. We will discuss the techniques and associated clinical outcomes for each, while including a brief mention of alternative treatments. Overall, cartilage restoration techniques have yielded favorable clinical outcomes and can be successfully employed to treat these challenging large focal lesions.

Uncompromised MRI of knee cartilage while incorporating sensitive sodium MRI

Sodium imaging is able to assess changes in ion content, linked to glycosaminoglycan content, which is important to guide orthopeadic procedures such as articular cartilage repair. Sodium imaging is ideally performed using double tuned RF coils, to combine high resolution morphological imaging with biochemical information from sodium imaging to assess ion content. The proton image quality of such coils is often harshly degraded, with up to 50% of SNR or severe acceleration loss as compared to single tuned coils. Reasons are that the number of proton receive channels often severely reduced and double tuning will degrade the intrinsic sensitivity of the RF coil on at least one of the nuclei. However, the aim of this work was to implement a double-tuned sodium/proton knee coil setup without deterioration of the proton signal whilst being able to achieve acquisition of high SNR sodium images. A double-tuned knee coil was constructed as a shielded birdcage optimized for sodium and compromised for proton. To exclude any compromise, the proton part of the birdcage is used for transmit only and interfaced to RF amplifiers that can fully mitigate the reduced efficiency. In addition, a 15 channel single tuned proton receiver coil was embedded within the double-resonant birdcage to maintain optimal SNR and acceleration for proton imaging. To validate the efficiency of our coil, the designed coil was compared with the state-of-the-art single-tuned alternative at 7 T. B1+ corrected SNR maps were used to compare both coils on proton performance and g-factor maps were used to compare both coils on acceleration possibilities. The newly constructed double-tuned coil was shown to have comparable proton quality and acceleration possibilities to the single-tuned alternative while also being able to acquire high SNR sodium images.

Effect of Delayed Primary Anterior Cruciate Ligament Reconstruction on Medial Compartment Cartilage and Meniscal Health

BACKGROUND

The time required to develop a secondary cartilage or meniscal injury in the medial compartment after anterior cruciate ligament (ACL) injury is not well understood.

PURPOSE

To determine the association between time delay until ACL reconstruction and the presence of medial compartment Outerbridge grade 3 or 4 chondral injury or medial meniscal tear requiring treatment.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 609 patients underwent primary ACL reconstruction at a single institution at a median 46 days between injury and surgery (61.4% male; mean age, 26.5 years [SD, 11.1]). Chondral status was graded according to Outerbridge criteria at the time of surgery. Multivariate regression analysis was used to assess the relationship between time delay until surgery and medial compartment chondral injury or meniscal injury requiring treatment. Adjustment was performed as needed for patient demographics, sporting activity, and prior knee injuries. Time until surgery had a nonlinear association with medial compartment health and was more effectively described in discrete intervals rather than as a continuous variable. The optimal time intervals to predict medial compartment health were determined by comparison of Bayes information criterion values between fully adjusted regression models.

RESULTS

After controlling for relevant confounders, delay of surgery >8 weeks had an increased likelihood of a medial meniscal tear requiring partial meniscectomy (adjusted odds ratio [aOR], 2.30; 95% CI, 1.04-5.12; P = .04) and a decreased likelihood of a meniscal tear requiring repair (aOR, 0.50; 95% CI, 0.32-0.76; P = .001). Delay of surgery >5 months had an increased likelihood of a medial Outerbridge grade ≥3 chondral defect (aOR, 3.11; 95% CI, 1.64-5.87; P = .001) or a grade 4 defect (aOR, 3.84; 95% CI, 1.75-8.45; P = .001).

CONCLUSION

From the time of ACL injury, risk of an irreparable medial meniscal tear found at the time of ACL reconstruction is significantly increased by 8 weeks, and risk of high-grade medial chondral damage is increased by 5 months.

OSTEOCHONDRAL ALLOGRAFT TRANSPLANTATION for the KNEE: POST-OPERATIVE REHABILITATION

Articular cartilage injuries of the knee are common among young, active patients presenting with knee pain, swelling, and/or mechanical symptoms. These injuries have limited healing potential due to the avascular nature of hyaline cartilage. While several treatment options exist, osteochondral allograft (OCA) transplantation for the knee has been used successfully in primary management of large chondral or osteochondral defects and salvage of previously failed cartilage repair. OCA transplantation potentially yields a natural, matching contour of the native recipient surface anatomy and transplants mature, viable hyaline cartilage to the affected defect. Following OCA transplantation, strict compliance with a rehabilitation protocol is essential to enable optimal recovery. The outlined rehabilitation protocol is informed by the existing literature and incorporates current rehabilitation principles, the science of osteochondral incorporation, and adaptations based on an individual's readiness to progress through subsequent phases. The purpose of this clinical commentary is to discuss the diagnosis, surgical management, and post-operative rehabilitation following OCA transplantation and to assist the physical therapist in returning athletes to full sports participation.

Lesion Size Measured on MRI Does Not Accurately Reflect Arthroscopic Measurement in Talar Osteochondral Lesions

Background:

Lesion size is a major determinant of treatment strategy for osteochondral lesions of the talus (OLTs). Although magnetic resonance imaging (MRI) is commonly used in the preoperative evaluation of OLTs, the reliability of the MRI measurement compared with the arthroscopic measurement is unknown.

Purpose:

To compare preoperative lesion size measured on MRI versus intraoperative lesion size measured during arthroscopy.

Study Design:

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

Methods:

We retrospectively reviewed a consecutive series of patients treated with bone marrow stimulation for OLTs. The diameter of the lesion was measured at its widest point in 2 planes, and MRI measurements were compared with those made during arthroscopy using a custom-made graduated probe.

Results:

A total of 39 patients with 45 OLTs were analyzed. Mean ± SD area measurements on MRI were significantly greater than the equivalent arthroscopic measurements (42.2 ± 30.5 vs 28.6 ± 23.1 mm², respectively; P = .03). Compared with the arthroscopic measurement, MRI overestimated OLT size in 53.3% (24/45) of ankles and underestimated OLT size in 24.4% (11/45). The mean MRI diameter measurement was significantly greater than the arthroscopic measurement in the coronal plane (MRI diameter vs arthroscopic measurement coronal plane, 6.1 ± 2.6 vs 4.9 ± 2.3 mm, P = .03; sagittal plane, 8.0 ± 3.6 vs 6.3 ± 3.6 mm, P = .05). Further, MRI overestimated coronal diameter in 48.9% (22/45) of ankles and underestimated in 26.7% (12/45) compared with the arthroscopic measurement. Similarly, sagittal plane MRI diameter measurements overestimated lesion size in 46.7% (21/45) of ankles and underestimated lesion size in 28.9% (13/45) compared with the arthroscopic findings.

Conclusion:

In a majority of lesions, MRI overestimated OLT area and diameter compared with arthroscopy. Surgeons should be aware of the discrepancies that can exist between MRI and arthroscopic measurements, as these data are important in making treatment decisions and educating patients.

Cartilage defect location and stiffness predispose the tibiofemoral joint to aberrant loading conditions during stance phase of gait

OBJECTIVES

The current study quantified the influence of cartilage defect location on the tibiofemoral load distribution during gait. Furthermore, changes in local mechanical stiffness representative for matrix damage or bone ingrowth were investigated. This may provide insights in the mechanical factors contributing to cartilage degeneration in the presence of an articular cartilage defect.

METHODS

The load distribution following cartilage defects was calculated using a musculoskeletal model that included tibiofemoral and patellofemoral joints with 6 degrees-of-freedom. Circular cartilage defects of 100 mm2 were created at different locations in the tibiofemoral contact geometry. By assigning different mechanical properties to these defect locations, softening and hardening of the tissue were evaluated.

RESULTS

Results indicate that cartilage defects located at the load-bearing area only affect the load distribution of the involved compartment. Cartilage defects in the central part of the tibia plateau and anterior-central part of the medial femoral condyle present the largest influence on load distribution. Softening at the defect location results in overloading, i.e., increased contact pressure and compressive strains, of the surrounding tissue. In contrast, inside the defect, the contact pressure decreases and the compressive strain increases. Hardening at the defect location presents the opposite results in load distribution compared to softening. Sensitivity analysis reveals that the surrounding contact pressure, contact force and compressive strain alter significantly when the elastic modulus is below 7 MPa or above 18 MPa.

CONCLUSION

Alterations in local mechanical behavior within the high load bearing area resulted in aberrant loading conditions, thereby potentially affecting the homeostatic balance not only at the defect but also at the tissue surrounding and opposing the defect. Especially, cartilage softening predisposes the tissue to loads that may contribute to accelerated risk of cartilage degeneration and the initiation or progression towards osteoarthritis of the whole compartment.

A Prospective, Blinded, Multicenter Clinical Trial to Compare the Efficacy, Accuracy, and Safety of In-Office Diagnostic Arthroscopy With Magnetic Resonance Imaging and Surgical Diagnostic Arthroscopy

PURPOSE

The purpose of this study was to compare the efficacy, accuracy, and safety of in-office diagnostic arthroscopy with magnetic resonance imaging (MRI) and surgical diagnostic arthroscopy.

METHODS

A prospective, blinded, multicenter, clinical trial was performed on 110 patients, ages 18 to 75 years, who presented with knee pain. The study period was April 2012 to April 2013. Each patient underwent a physical examination, an MRI, in-office diagnostic imaging, and a diagnostic arthroscopic examination in the operating room. The attending physician completed clinical report forms comparing the in-office arthroscopic examination and surgical diagnostic arthroscopy findings on each patient. Two blinded experts, unaffiliated with the clinical care of the study's subjects, reviewed the in-office arthroscopic images and MRI images using the surgical diagnostic arthroscopy images as the "control" group comparison. Patients were consecutive, and no patients were excluded from the study.

RESULTS

In this study, the accuracy, sensitivity, and specificity of in-office arthroscopy was equivalent to surgical diagnostic arthroscopy and more accurate than MRI. When comparing in-office arthroscopy with surgical diagnostic arthroscopy, all kappa statistics were between 0.766 and 0.902. For MRI compared with surgical diagnostic arthroscopy, kappa values ranged from a low of 0.130 (considered "slight" agreement) to a high of 0.535 (considered "moderate" agreement). The comparison of MRI to in-office arthroscopy showed very similar results as the comparison of MRI with surgical diagnostic arthroscopy, ranging from a low kappa of 0.112 (slight agreement) to a high of 0.546 (moderate agreement). There were no patient-related or device-related complications related to the use of in-office arthroscopy.

CONCLUSIONS

Needle-based diagnostic imaging that can be used in the office setting is statistically equivalent to surgical diagnostic arthroscopy with regard to the diagnosis of intra-articular, nonligamentous knee joint pathology. In-office diagnostic imaging can provide a more detailed and accurate diagnostic assessment of intra-articular knee pathology than MRI. Based on the study results, in-office diagnostic imaging provides a safe, accurate, real-time, minimally invasive diagnostic modality to evaluate intra-articular pathology without the need for surgical diagnostic arthroscopy or high-cost imaging.

LEVEL OF EVIDENCE

Level II, comparative prospective trial.

Diagnosis: History, Physical Examination, Imaging, and Arthroscopy: Proceedings of the International Consensus Meeting on Cartilage Repair of the Ankle

BACKGROUND

The evidence supporting best practice guidelines in the field of cartilage repair of the ankle are based on both low quality and low levels of evidence. Therefore, an international consensus group of experts was convened to collaboratively advance toward consensus opinions based on the best available evidence on key topics within cartilage repair of the ankle. The purpose of this article is to report the consensus statements on "Diagnosis: History, Physical Examination, Imaging, and Arthroscopy" developed at the 2017 International Consensus Meeting on Cartilage Repair of the Ankle.

METHODS

Seventy-five international experts in cartilage repair of the ankle representing 25 countries and 1 territory were convened and participated in a process based on the Delphi method of achieving consensus. Questions and statements were drafted within 11 working groups focusing on specific topics within cartilage repair of the ankle, after which a comprehensive literature review was performed and the available evidence for each statement was graded. Discussion and debate occurred in cases where statements were not agreed upon in unanimous fashion within the working groups. A final vote was then held, and the strength of consensus was characterized as follows: consensus: 51 - 74%; strong consensus: 75 - 99%; unanimous: 100%.

RESULTS

A total of 12 statements on the diagnosis of cartilage injuries of the ankle reached consensus during the 2017 International Consensus Meeting on Cartilage Repair of the Ankle. Two achieved unanimous support and 10 reached strong consensus (greater than 75% agreement). All statements reached at least 86% agreement.

CONCLUSIONS

This international consensus derived from leaders in the field will assist clinicians in the diagnosis of cartilage injuries of the ankle.

Large Osteochondral Allografts of the Knee: Surgical Technique and Indications

Large osteochondral allograft (OCA) transplant has become a valid alternative to restore articular surface in challenging articular lesions in young and active patients, either in primary or in revision procedures. Several studies support the effectiveness and safety of OCA, but costs and graft availability limit their use. The indications are the treatment of symptomatic full-thickness cartilage lesions greater than 3 cm ² , deep lesions with subchondral damage, or revision procedures when a previous treatment has failed. The goal of the transplant is to restore the articular surface with a biological implant, allow return to daily/sports activities, relieve symptoms, and delay knee arthroplasty. Grafts can be fresh, fresh-frozen, or cryopreserved; these different storage procedures significantly affect cell viability, immunogenicity, and duration of the storage. Dowel and shell technique are the two most commonly used procedures for OCA transplantation. While most cartilage lesions can be treated with the dowel technique, large and/or geometrically irregular lesions should be treated with the shell technique. OCA transplantation for the knee has demonstrated reliable mid- to long-term results in terms of graft survival and patient satisfaction. Best results are reported: in unipolar lesions, in patients younger than 30 years, in traumatic lesions and when the treatment is performed within 12 months from the onset of symptoms.

Degenerative changes after posterior cruciate ligament reconstruction are irrespective of posterior knee stability: MRI-based long-term results

INTRODUCTION

Posterior cruciate ligament reconstruction (PCLR) is advocated to prevent an early onset of osteoarthritis. We hypothesized that posterior instability after PCLR correlates with degenerative changes.

MATERIALS AND METHODS

MRIs of 42 (12 female/30 male; 39 ± 9 years) patients were enrolled with a minimum 5-year follow-up (FFU) after PCLR. In addition, 25 contralateral and 15 follow-up MRIs (12 months after baseline) were performed. Degenerative changes were graded using WORMS. Posterior tibial translation (PTT) was measured using posterior stress radiographs. Outcome parameters included WORMS/cartilage subscore for the whole joint, patellofemoral (PFJ), medial (MFTJ), and lateral femorotibial joint (LFTJ).

RESULTS

Final follow-up was 101 (range 68-168) months. WORMS reached 41.5 [18.5-56.8]. Regional WORMS for PFJ was significantly higher than MFTJ and LFTJ. Cartilage subscore yielded 7 [2.8-15]. MFTJ and PFJ were significantly higher than LFTJ. Primary outcome parameters were significantly higher than the contralateral knee (P < 0.0001) and significantly increased within 12 months (P = 0.0002). There was a significant correlation between the intraoperative degree of cartilage injury and WORMS (P < 0.0001 with r = 0.64) and between the number of previous surgery and the cartilage subscore (P = 0.03 with r = 0.32). Meniscal surgery led to a significantly higher WORMS (P = 0.035). Combined risk models revealed that women below the mean age had significantly lower WORMS (P = 0.001) and cartilage subscores (P = 0.003).

CONCLUSIONS

Patients undergo degenerative changes after PCLR, which are significantly higher compared to the contralateral knee. These occur predominantly at PFJ/MFTJ and are irrespective of posterior stability. Concomitant meniscus/cartilage injuries and a high number of previous surgeries are further risk factors.

The Benefits of an In-Office Arthroscopy in the Diagnosis of Unresolved Knee Pain

We report a patient who developed persistent knee pain with mechanical symptoms after an uncomplicated patellofemoral arthroplasty. The etiology of his knee pain remained inconclusive following magnetic resonance imaging due to metallic artifact image distortion. With the use of an in-office needle arthroscopy, an immediate and definitive diagnosis was obtained, preventing an unnecessary surgery for a diagnostic arthroscopy. We discovered a lateral meniscus tear, an anterior cruciate ligament tear, and a medial femoral condyle chondral defect for which the patient underwent arthroscopic partial meniscectomy, ligament reconstruction, and osteochondral allograft transplantation, with resolution of his knee pain.

Use of MRI by radiologists and orthopaedic surgeons to detect intra-articular injuries of the knee

OBJECTIVE

Magnetic resonance imaging (MRI) is paramount in the assessment of knee pathology, particularly when planning for a surgical procedure. This study compared the diagnostic accuracy in MRI reading of pathological knees by radiologists and orthopaedic surgeons.

MATERIALS AND METHODS

Cross-sectional study comprising 80 randomly selected patients previously submitted to arthroscopic surgery after clinical examination and MRI. A diagnosis by MRI interpretation was requested from the two teams, one of radiologists and another of orthopaedic surgeons. The conclusions of each team were later compared. Statistical significance was considered for p < 0.05.

RESULTS

The radiologists' findings achieved statistical significance regarding osteochondral injuries, ACL, and medial meniscus (p < 0.05), and orthopaedic surgeons regarding ACL injuries and menisci (p < 0.05). ACL injuries demonstrated a statistically significant association between teams (p < 0.001).

CONCLUSIONS

MRI appears to offer reliable readings of ACL injuries, regardless the specialty of the observer. The lateral compartment is scarcely well read.

In-office arthroscopy for the evaluation of chronic knee pain: A case report

This is a case report detailing the use of in-office needle arthroscopy (mi-eye 2™) in a patient with chronic knee pain and inconclusive magnetic resonance imaging findings. The patient is a 40-year-old male who presented to our clinic after an extended history of right knee pain along the medial aspect with previous failed treatments. Magnetic resonance imaging without contrast had demonstrated full-thickness chondral fissuring of the lateral patellar facet, mild abnormal signals of the proximal patellar tendon and Hoffa’s fat pad, and intact anterior cruciate ligament and posterior cruciate ligament. The patient was previously treated with an ultrasound-guided injection of 2 cm³ of 1% lidocaine without epinephrine and 1 cm³ of Kenalog-40 and scheduled for follow-up. At follow-up, clinical examination showed antalgic gait, minimal tenderness along medial joint line, medial pain in deep flexion, and no pain when in varus or valgus. Due to continued discomfort with a negative magnetic resonance imaging, in-office diagnostic arthroscopy was performed using mi-eye 2 revealing a tear of the mid-body of the medial meniscus. The patient subsequently underwent arthroscopic repair and is recovering well with complete resolution of medial joint pain. This report highlights the clinical utility of in-office diagnostic arthroscopy in the management of patients with persistent knee pain and negative or equivocal findings on magnetic resonance imaging.

Magnetic Resonance Imaging for Patellofemoral Chondromalacia: Is There a Role for T2 Mapping?

Background:

Patellofemoral pain is common, and treatment is guided by the presence and grade of chondromalacia.

Purpose:

To evaluate and compare the sensitivity and specificity in detecting and grading chondral abnormalities of the patella between proton density fat suppression (PDFS) and T2 mapping magnetic resonance imaging (MRI).

Study Design:

Cohort study; Level of evidence, 2.

Methods:

A total of 25 patients who underwent MRI of the knee with both a PDFS sequence and T2 mapping and subsequently underwent arthroscopic knee surgery were included. The cartilage surface of the patella was graded on both MRI sequences by 2 independent, blinded radiologists. Cartilage was then graded during arthroscopic surgery by a sports medicine fellowship–trained orthopaedic surgeon. Reliability, sensitivity, specificity, and accuracy were determined for both MRI methods. The findings during arthroscopic surgery were considered the gold standard.

Results:

Intraobserver and interobserver agreement for both PDFS (98.5% and 89.4%, respectively) and T2 mapping (99.4% and 91.3%, respectively) MRI were excellent. For T2 mapping, the sensitivity (61%) and specificity (64%) were comparable, whereas for PDFS there was a lower sensitivity (37%) but higher specificity (81%) in identifying cartilage abnormalities. This resulted in a similar accuracy for PDFS (59%) and T2 mapping (62%).

Conclusion:

Both PDFS and T2 mapping MRI were reliable but only moderately accurate in predicting patellar chondromalacia found during knee arthroscopic surgery.

Magnetic Resonance Imaging Score and Classification System (AMADEUS) for Assessment of Preoperative Cartilage Defect Severity

Objective To design a simple magnetic resonance (MR)-based assessment system for quantification of osteochondral defect severity prior to cartilage repair surgery at the knee. Design The new scoring tool was supposed to include 3 different parameters: (1) cartilage defect size, (2) depth/morphology of the cartilage defect, and (3) subchondral bone quality, resulting in a specific 3-digit code. A clearly defined numeric score was developed, resulting in a final score of 0 to 100. Defect severity grades I through IV were defined. For intra- and interobserver agreement, defects were assessed by 2 independent readers on preoperative knee MR images of n = 44 subjects who subsequently received cartilage repair surgery. For statistical analyses, mean values ± standard deviation (SD), interclass correlation coefficients (ICC), and linear weighted kappa values were calculated. Results The mean total Area Measurement And DEpth & Underlying Structures (AMADEUS) score was 48 ± 24, (range, 0-85). The mean defect size was 2.8 ± 2.6 cm². There were 36 of 44 full-thickness defects. The subchondral bone showed defects in 21 of 44 cases. Kappa values for intraobserver reliability ranged between 0.82 and 0.94. Kappa values for interobserver reliability ranged between 0.38 and 0.85. Kappa values for AMADEUS grade were 0.75 and 0.67 for intra- and interobserver agreement, respectively. ICC scores for the AMADEUS total score were 0.97 and 0.96 for intra- and interobserver agreement, respectively. Conclusions The AMADEUS score and classification system allows reliable severity encoding, scoring and grading of osteochondral defects on knee MR images, which is easily clinically applicable in daily practice.

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.

Osteochondral lesion depth on MRI can help predict the need for a sandwich procedure

PURPOSE

Autologous subchondral bone grafting in combination with autologous chondrocyte implantation (ACI) (sandwich procedure) is a well-accepted procedure for the treatment of osteochondral lesions of the knee. This requires a different surgical technique and preoperative planning compared to ACI alone. In addition, pain from bone marrow donor site locations can be expected and should be part of patient consent and expectations. This study evaluates whether the MRI made as part of the standard preoperative cartilage patient work up has the diagnostic accuracy to predict the need for a sandwich procedure.

METHODS AND MATERIALS

Retrospectively, 185 preoperative MRI scans (PD and T2 sequences) of patients planned for ACI were included. The integrity of the subchondral bone and lamina was scored by four different observers (3 radiologists, and 1 orthopaedic resident). The depth of the defect was measured perpendicular from articulating surface to the bottom of the bony lesion. The area under the curve (AUC) for subchondral defect on MRI (i.e. lamina or bone defect or expert impression), depth measurements and eventual sandwich procedure were calculated. Also inter-observer Kappa values were determined.

RESULTS

The AUCs for lamina (0.74-0.80) and bone defect (0.73-0.79) were fair and inter-observer Kappas ranged from 0.49 to 0.76, indicating a moderate-good inter-observer agreement and moderate prediction of the need for a sandwich procedure based on the presence of lamina and or subchondral bone defect on MRI. However, depth measurements resulted in an AUC of 0.90 (95% CI: 0.84-0.95,) with an optimal cut-off point at 6.5mm depth of the lesion (90% sensitivity, 80% specificity) to predict the need for a sandwich procedure.

CONCLUSION

Ours is the first study examining MRI as a diagnostic tool in predicting the need for a sandwich procedure. Our results show that the integrity of the subchondral layer on MRI has a moderate role in predicting the need for an eventual autologous bone graft to augment ACI whereas in our cohort a depth of the lesion above 6.5mm accurately predicts the need for a sandwich procedure. This can aid in optimising the preoperative planning and patient consent.

Lesion Size Is a Predictor of Clinical Outcomes After Bone Marrow Stimulation for Osteochondral Lesions of the Talus: A Systematic Review

BACKGROUND

The critical lesion size treated with bone marrow stimulation (BMS) for osteochondral lesions of the talus (OLTs) has been 150 mm² in area or 15 mm in diameter. However, recent investigations have failed to detect a significant correlation between the lesion size and clinical outcomes after BMS for OLTs.

PURPOSE

To systematically review clinical studies reporting both the lesion size and clinical outcomes after BMS for OLTs.

STUDY DESIGN

Systematic review.

METHODS

A systematic search of the MEDLINE and EMBASE databases was performed in March 2015 based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Included studies were evaluated with regard to the level of evidence (LOE), quality of evidence (QOE), lesion size, and clinical outcomes.

RESULTS

Twenty-five studies with 1868 ankles were included; 88% were either LOE 3 or 4, and 96% did not have good QOE. The mean area was 103.8 ± 10.2 mm² in 20 studies, and the mean diameter was 10.0 ± 3.2 mm in 5 studies. The mean American Orthopaedic Foot and Ankle Society score improved from 62.4 ± 7.9 preoperatively to 83.9 ± 9.2 at a mean 54.1-month follow-up in 14 studies reporting both preoperative and postoperative scores with a mean follow-up of more than 2 years. A significant correlation was found in 3 studies, with a mean lesion area of 107.4 ± 10.4 mm², while none was reported in 8 studies, with a mean lesion area of 85.3 ± 9.2 mm². The lesion diameter significantly correlated with clinical outcomes in 2 studies (mean diameter, 10.2 ± 3.2 mm), whereas none was found in 2 studies (mean diameter, 8.8 ± 0.0 mm). However, the reported lesion size measurement method and evaluation method of clinical outcomes widely varied among the studies.

CONCLUSION

An assessment of the currently available data does suggest that BMS may best be reserved for OLT sizes less than 107.4 mm² in area and/or 10.2 mm in diameter. Future development in legitimate prognostic size guidelines based on high-quality evidence that correlate with outcomes will surely provide patients with the best potential for successful long-term outcomes.

Macroscopic cartilage repair scoring of defect fill, integration and total points correlate with corresponding items in histological scoring systems - a study in adult sheep

OBJECTIVE

To correlate osteochondral repair assessed by validated macroscopic scoring systems with established semiquantitative histological analyses in an ovine model and to test the hypothesis that important macroscopic individual categories correlate with their corresponding histological counterparts.

METHODS

In the weight-bearing portion of medial femoral condyles (n = 38) of 19 female adult Merino sheep (age 2-4 years; weight 70 ± 20 kg) full-thickness chondral defects were created (size 4 × 8 mm; International Cartilage Repair Society (ICRS) grade 3C) and treated with Pridie drilling. After sacrifice, 1520 blinded macroscopic observations from three observers at 2-3 time points including five different macroscopic scoring systems demonstrating all grades of cartilage repair where correlated with corresponding categories from 418 blinded histological sections.

RESULTS

Categories "defect fill" and "total points" of different macroscopic scoring systems correlated well with their histological counterparts from the Wakitani and Sellers scores (all P ≤ 0.001). "Integration" was assessed in both histological scoring systems and in the macroscopic ICRS, Oswestry and Jung scores. Here, a significant relationship always existed (0.020 ≤ P ≤ 0.049), except for Wakitani and Oswestry (P = 0.054). No relationship was observed for the "surface" between histology and macroscopy (all P > 0.05).

CONCLUSIONS

Major individual morphological categories "defect fill" and "integration", and "total points" of macroscopic scoring systems correlate with their corresponding categories in elementary and complex histological scoring systems. Thus, macroscopy allows to precisely predict key histological aspects of articular cartilage repair, underlining the specific value of macroscopic scoring for examining cartilage repair.

New approach for predictive measurement of knee cartilage defects with three-dimensional printing based on CT-arthrography: A feasibility study

PURPOSE

The aim was to prove the possibility of creating an exact module of knee cartilage defects using 3D printing.

METHODS

Defects were created in cadaver knees. CT-arthrography and 3-Tesla MRI were performed. Based on CTA images a model of the cartilage was created using 3D printing. Defect-sizes in the imaging modalities were compared.

RESULTS

Estimated lesion area in 3D model differed approximately 5% comparing to the defect sizes in knees. MRI underestimated the defect on average of 12%, whereas the CTA overestimated the defect about 3%.

CONCLUSIONS

We proved the feasibility of creating an accurate module of knee cartilage.