A review of the differences between normal and osteoarthritis articular cartilage in human knee and ankle joints

Osteochondral Injuries of the Talus

Osteochondral lesions of the talus are a common sequelae of trauma and are often associated with ankle sprains and ankle fractures. Because the surface of the talus is composed primarily of hyaline cartilage, the regenerative capacity of these injuries is limited. Therefore, several open and arthroscopic techniques have been described to treat osteochondral injuries of the talus and underlying bone marrow lesions. Throughout this review, these treatment options are discussed along with their indications and currently reported outcomes. A commentary on the authors' preferences among these techniques is also provided.

Change of joint line convergence angle and other coronal alignments after total hip arthroplasty

BACKGROUND

The purpose of this study was to determine the unloading effect of total hip arthroplasty (THA) on the ipsilateral knee joint through the joint line convergence angle (JLCA) change and determine the changes in other coronal radiographic parameters after THA, and evaluate the sensitivity of JLCA.

PATIENTS AND METHODS

We retrospectively assessed 70 patients who underwent unilateral THA. Hip parameters such as neck shaft angle (NSA), neck length, and femoral offset and coronal alignment parameters of the lower extremity such as hip-knee-ankle angle (HKA), femur length, mechanical lateral distal femoral angle (mLDFA), JLCA, medial proximal tibial angle (MPTA), lateral distal tibial angle (LDTA), and plafond talus angle (PTA) were measured in the operative and non-operative sides. We compared all hip and coronal alignment parameters between before and 1 year after THA, and the amount of standardized changes (Δ) between all hip and coronal alignment parameters on the operative side, respectively.

RESULTS

All mean hip and coronal alignment parameters on the operative side changed significantly 1-year after THA; however, those on the non-operative side did not. On the operative side, mean JLCA and PTA changed in the direction of closing the joint lateral space, from 1.81° and 0.47° to 1.22° and 0.11°, respectively (p<0.001 and 0.046, respectively). Mean NSA, HKA, and mLDFA changed in the valgus direction, from 129.39°, 2.62°, and 86.69° to 133.54°, 1.53°, and 85.91°, respectively (p<0.001). Mean femoral offset, neck length, and femur length increased from 36.45mm, 47.83mm, and 429.20mm to 39.85mm, 55.06mm, and 436.33mm, respectively (p<0.001). Mean MPTA and LDTA increased from 85.43° and 87.50° to 86.73° and 90.38, respectively (p<0.001). JLCA was more vulnerable to change than HKA, femur length, mLDFA, MPTA, and PTA (p<0.05).

DISCUSSION

JLCA change on the operative side was more sensitive than changes of other coronal alignments after THA. According to the cohort, THA might have an unloading effect on the medial compartment of the knee joint.

LEVEL OF EVIDENCE

IV; retrospective case-control and cohort studies.

The Ankle Joint: Non-Operative Updates in Ankle Arthritis, Are Biologics Working?

The vast majority of ankle arthritis is post-traumatic in nature, with rates of 60% to 80%. Symptoms include pain, decreased range of motion, and joint effusion. Diagnostic imaging is helpful in determining the degree of joint degeneration, with MRI and CT scan being the most sensitive. Conservative treatment modalities are targeted at reducing symptoms and improving function. Injectable therapy has gained popularity over the last few decades, with advancements in biologic treatments. Corticosteroids, hyaluronic acid, platelet-rich plasma, and amniotic tissue-derived products can be used to reduce inflammation in the joint, as well as prevent cartilage degeneration.

Arthroscopic Cartilage Transplantation

Arthroscopic cartilage repair has made several strides in recent years; however, no gold standard for cartilage restoration has been found. Simple treatment with bone marrow stimulation such as microfracture have shown good short-term results; however, concerns for long-term stability of cartilage repair as well as the subchondral bone health remain in question. Treatment of these lesions often comes down to surgeon preference, the aim of this study is to discuss some of the current options available on the market to further assist surgeons in their decision-making process.

Decrease in Glycosaminoglycan with Aging in Normal Rat Articular Cartilage Is Greater in Females than in Males

OBJECTIVE

Osteoarthritis (OA) is more prevalent in females. We hypothesized that changes in articular cartilage (AC) constituents with aging may cause differences. Herein, we aimed to compare the changes in AC constituents with aging in male and female normal rats.

DESIGN

The glycosaminoglycan (GAG) and collagen (COL) contents of the AC in knee, hip, and shoulder joints of male and female rats were quantified and compared between age groups and sexes.

RESULTS

The amount of GAG was decreased in multiple joints in both males and females with aging. In females, it had a significant decrease in all joints measured. The decrease in GAG with aging was more severe in females than in males. Even in young rats, the amount of knee joint GAG was significantly less in females than in males. The amount of COL in the AC was unchanged with aging in both sexes.

CONCLUSIONS

The drastic GAG decrease with aging in female normal rats may explain the higher prevalence and more severe OA in females.

Accelerated Discovery of the Polymer Blends for Cartilage Repair through Data-Mining Tools and Machine-Learning Algorithm

In designing successful cartilage substitutes, the selection of scaffold materials plays a central role, among several other important factors. In an empirical approach, the selection of the most appropriate polymer(s) for cartilage repair is an expensive and time-consuming affair, as traditionally it requires numerous trials. Moreover, it is humanly impossible to go through the huge library of literature available on the potential polymer(s) and to correlate the physical, mechanical, and biological properties that might be suitable for cartilage tissue engineering. Hence, the objective of this study is to implement an inverse design approach to predict the best polymer(s)/blend(s) for cartilage repair by using a machine-learning algorithm (i.e., multinomial logistic regression (MNLR)). Initially, a systematic bibliometric analysis on cartilage repair has been performed by using the bibliometrix package in the R program. Then, the database was created by extracting the mechanical properties of the most frequently used polymers/blends from the PoLyInfo library by using data-mining tools. Then, an MNLR algorithm was run by using the mechanical properties of the polymers, which are similar to the cartilages, as the input and the polymer(s)/blends as the predicted output. The MNLR algorithm used in this study predicts polyethylene/polyethylene-graftpoly(maleic anhydride) blend as the best candidate for cartilage repair.

A Novel Hybrid Approach Based on Deep CNN Features to Detect Knee Osteoarthritis

In the recent era, various diseases have severely affected the lifestyle of individuals, especially adults. Among these, bone diseases, including Knee Osteoarthritis (KOA), have a great impact on quality of life. KOA is a knee joint problem mainly produced due to decreased Articular Cartilage between femur and tibia bones, producing severe joint pain, effusion, joint movement constraints and gait anomalies. To address these issues, this study presents a novel KOA detection at early stages using deep learning-based feature extraction and classification. Firstly, the input X-ray images are preprocessed, and then the Region of Interest (ROI) is extracted through segmentation. Secondly, features are extracted from preprocessed X-ray images containing knee joint space width using hybrid feature descriptors such as Convolutional Neural Network (CNN) through Local Binary Patterns (LBP) and CNN using Histogram of oriented gradient (HOG). Low-level features are computed by HOG, while texture features are computed employing the LBP descriptor. Lastly, multi-class classifiers, that is, Support Vector Machine (SVM), Random Forest (RF), and K-Nearest Neighbour (KNN), are used for the classification of KOA according to the Kellgren-Lawrence (KL) system. The Kellgren-Lawrence system consists of Grade I, Grade II, Grade III, and Grade IV. Experimental evaluation is performed on various combinations of the proposed framework. The experimental results show that the HOG features descriptor provides approximately 97% accuracy for the early detection and classification of KOA for all four grades of KL.

Pathogenesis of Posttraumatic Osteoarthritis of the Ankle

Ankle osteoarthritis affects a significant portion of the global adult population. Unlike other joints, arthritis of the ankle often develops as a response to traumatic injury (intra-articular fracture) of the ankle joints. The full mechanism leading to posttraumatic osteoarthritis of the ankle (PTOAA) is poorly understood. These deficits in knowledge pose challenges in the management of the disease. Adequate surgical reduction of fractured ankle joints remains the gold standard in prevention. The purpose of this review is to thoroughly delineate the known pathogenesis of PTOAA, and provide critical updates on this pathology and new avenues to provide therapeutic management of the disease.

Detection of proteoglycan loss from articular cartilage using Brillouin microscopy, with applications to osteoarthritis

The degeneration of articular cartilage (AC) occurs in osteoarthritis (OA), which is a leading cause of pain and disability in middle-aged and older people. The early disease-related changes in cartilage extra-cellular matrix (ECM) start with depletion of proteoglycan (PG), leading to an increase in tissue hydration and permeability. These early compositional changes are small (<10%) and hence difficult to register with conventional non-invasive imaging technologies (magnetic resonance and ultrasound imaging). Here we apply Brillouin microscopy for detecting changes in the mechanical properties and composition of porcine AC. OA-like degradation is mimicked by enzymatic tissue digestion, and we compare Brillouin microscopy measurements against histological staining of PG depletion over varying digestion times and enzyme concentrations. The non-destructive nature of Brillouin imaging technology opens new avenues for creating minimally invasive arthroscopic devices for OA diagnostics and therapeutic monitoring.

Antinociceptive effects of hyaluronic acid on monoiodoacetate-induced ankle osteoarthritis in rats

Purpose

Ankle osteoarthritis (OA) causes significant pain and debilitation; yet, its underlying mechanisms remain unclear. Clinically, hyaluronic acid (HA) is widely used to treat OA. The present study aimed to investigate the roles of HA in pain-related behavior, joint function, swelling, and pathological changes in cartilage in a rat model of monoiodoacetate (MIA)-induced ankle OA.

Materials and methods

Male Sprague Dawley rats were assigned to three experimental groups as follows: 1) MIA rats injected with 1 mg MIA in the right tibiotarsal joint for two consecutive days; 2) sham rats injected with saline instead of MIA; and 3) MIA-HA rats injected with HA in the tibiotarsal joint at 7, 14, and 21 days after MIA injection. Joint swelling, range of motion (ROM), and pain-related behavior were evaluated 1 day before and on the 7th, 14th, 21st, and 28th day after MIA or saline injection. Pathological changes in the ankle joint were assessed 28 days after MIA or saline injection.

Results

No significant difference in the degree of ankle swelling or ROM reduction was observed between MIA rats and MIA-HA rats. However, compared with those in MIA rats, mechanical and thermal hypersensitivity was significantly reduced and stride length significantly improved in MIA-HA rats. Histologic analysis revealed that cartilage degeneration was significantly suppressed in MIA-HA rats compared with that in MIA rats, reflecting the chondroprotective effects of HA.

Conclusion

HA improved pain-related behavior and stride length and suppressed MIA-induced cartilage degeneration. HA may thus inhibit OA progression and suppress peripheral and/or central sensitization.

Establishment of rat ankle post-traumatic osteoarthritis model induced by malleolus fracture

BACKGROUND

Malleolar fracture, which is present in 37-53% of human ankle osteoarthritis (OA), is the most common type of fracture in the ankle joint. In spite of this, no rat animal model has been developed for this type of injury to date. Here, we established a rat ankle post-traumatic OA (PTOA) model induced by malleolar fracture; this model will be useful in ankle OA research.

METHODS

Two-month-old male Sprague Dawley (SD) rats were randomized into 2 groups (n = 19 per group): 1) malleolus articular fracture, dislocation, and immediate reduction on the right joints and 2) malleolus articular fracture on the right ankle. The contralateral ankle joints were used as controls. The fracture and healing processes were confirmed and monitored by radiography. Changes in inflammation were monitored in vivo by fluorescence molecular tomography (FMT). Cartilage damage and changes in expression of OA-related genes were analyzed by histology, immunohistochemistry, Real-time quantitative PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA) at 8 weeks post-surgery.

RESULTS

X-rays showed that all fractures were healed at 8 weeks post-surgery. A reproducible, mild to moderate degree of OA cartilage damage with reduced aggrecan was detected by histology in all animals in both groups but there was no significant difference between the two groups. Decreased Col-II and increased Col-X and MMP-13 levels were detected by qPCR, immunohistochemistry, ELISA and FMT from both groups cartilage.

CONCLUSIONS

Malleolus articular fracture alone induces ankle OA with lesions on the central weight bearing area of the tibiotalar joint in rats. This model will provide a reproducible and useful tool for researchers to study ankle OA.

Advances in Ankle Cartilage Repair

Repair of osteochondral lesions of the talus can be difficult. Smaller lesions respond well to simple arthroscopy and microfracture, whereas larger cystic lesions may require allograft talus replacement or ankle fusions. The lesions in between are more difficult to treat. Autologous chondrocyte implantation and matrix-associated autologous chondrocyte implantation have shown promising results. Future research may include new techniques, pharmacologic intervention, and cell-based therapies, and may be better served with prospective observational studies instead of costly randomized controlled studies. A representative example of arthroscopic implantation is given.

Measuring clinically relevant endpoints in a serum-free, three-dimensional, primary cell culture system of human osteoarthritic articular chondrocytes

Osteoarthritis (OA) is characterized by degeneration of articular cartilage within the joint, inflammation and pain. The purpose of this study was to develop a primary, serum free cell culture system of human osteoarthritic articular chondrocytes (HOACs) with which to study manifestations of the disease process. Joint tissues were obtained from OA patients undergoing total knee arthroplasty (TKA). HOACs isolated from the femoral condyles and tibial plateau of the same side were combined, plated in three-dimensional, alginate beads and cultured for five days in serum, hormone and protein free medium. More living cells were obtained from the femoral condyles than the tibial plateau. The optimal plating density was 2.5 × 10⁶ cells/ml of alginate. The amounts of DNA, RNA, proteoglycans and total collagen were similar in cultures prepared from the sides of least and greatest pathology. More type 1 than type 2 collagen was detected in the medium on days 2 and 5. A greater percentage of type 1 than type 2 collagen was degraded. The inflammatory cytokine interleukin-1 beta was present in the medium and alginate associated matrix. Although variation in the metabolic profiles between subjects was observed, HOACs from all patients continued to reflect the OA phenotype for five days in culture. This serum free, three-dimensional primary culture system of HOACs provides a platform with which to measure clinically relevant endpoints of OA and screen potential disease modifying OA therapeutics.

Post-traumatic osteoarthritis of the ankle: A distinct clinical entity requiring new research approaches

The diagnosis of ankle osteoarthritis (OA) is increasing as a result of advancements in non-invasive imaging modalities such as magnetic resonance imaging, improved arthroscopic surgical technology and heightened awareness among clinicians. Unlike OA of the knee, primary or age-related ankle OA is rare, with the majority of ankle OA classified as post-traumatic (PTOA). Ankle trauma, more specifically ankle sprain, is the single most common athletic injury, and no effective therapies are available to prevent or slow progression of PTOA. Despite the high incidence of ankle trauma and OA, ankle-related OA research is sparse, with the majority of clinical and basic studies pertaining to the knee joint. Fundamental differences exist between joints including their structure and molecular composition, response to trauma, susceptibility to OA, clinical manifestations of disease, and response to treatment. Considerable evidence suggests that research findings from knee should not be extrapolated to the ankle, however few ankle-specific preclinical models of PTOA are currently available. The objective of this article is to review the current state of ankle OA investigation, highlighting important differences between the ankle and knee that may limit the extent to which research findings from knee models are applicable to the ankle joint. Considerations for the development of new ankle-specific, clinically relevant animal models are discussed. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:440-453, 2017.

Adipose, Bone Marrow and Synovial Joint-Derived Mesenchymal Stem Cells for Cartilage Repair

Current cell-based repair strategies have proven unsuccessful for treating cartilage defects and osteoarthritic lesions, consequently advances in innovative therapeutics are required and mesenchymal stem cell-based (MSC) therapies are an expanding area of investigation. MSCs are capable of differentiating into multiple cell lineages and exerting paracrine effects. Due to their easy isolation, expansion, and low immunogenicity, MSCs are an attractive option for regenerative medicine for joint repair. Recent studies have identified several MSC tissue reservoirs including in adipose tissue, bone marrow, cartilage, periosteum, and muscle. MSCs isolated from these discrete tissue niches exhibit distinct biological activities, and have enhanced regenerative potentials for different tissue types. Each MSC type has advantages and disadvantages for cartilage repair and their use in a clinical setting is a balance between expediency and effectiveness. In this review we explore the challenges associated with cartilage repair and regeneration using MSC-based cell therapies and provide an overview of phenotype, biological activities, and functional properties for each MSC population. This paper also specifically explores the therapeutic potential of each type of MSC, particularly focusing on which cells are capable of producing stratified hyaline-like articular cartilage regeneration. Finally we highlight areas for future investigation. Given that patients present with a variety of problems it is unlikely that cartilage regeneration will be a simple "one size fits all," but more likely an array of solutions that need to be applied systematically to achieve regeneration of a biomechanically competent repair tissue.

Comparison of mouse and human ankles and establishment of mouse ankle osteoarthritis models by surgically-induced instability

OBJECTIVE

Prevalence of ankle osteoarthritis (OA) is lower than that of knee OA, however, the molecular mechanisms underlying the difference remain unrevealed. In the present study, we developed mouse ankle OA models for use as tools to investigate pathophysiology of ankle OA and molecular characteristics of ankle cartilage.

DESIGN

We anatomically and histologically examined ankle and knee joints of C57BL/6 mice, and compared them with human samples. We examined joints of 8-week-old and 25-month-old mice. For experimental models, we developed three different ankle OA models: a medial model, a lateral model, and a bilateral model, by resection of respective structures. OA severity was evaluated 8 weeks after the surgery by safranin O staining, and cartilage degradation in the medial model was sequentially examined.

RESULTS

Anatomical and histological features of human and mouse ankle joints were comparable. Additionally, the mouse ankle joint was more resistant to cartilage degeneration with aging than the mouse knee joint. In the medial model, the tibiotalar joint was markedly affected while the subtalar joint was less degenerated. In the lateral model, the subtalar joint was mainly affected while the tibiotalar joint was less altered. In the bilateral model, both joints were markedly degenerated. In the time course of the medial model, TdT-mediated dUTP nick end labeling (TUNEL) staining and Adamts5 expression were enhanced at early and middle stages, while Mmp13 expression was gradually increased during the OA development.

CONCLUSION

Since human and mouse ankles are comparable, the present models will contribute to ankle OA pathophysiology and general cartilage research in future.

Obesity is associated with higher absolute tibiofemoral contact and muscle forces during gait with and without knee osteoarthritis

BACKGROUND

Obesity is an important risk factor for knee osteoarthritis initiation and progression. However, it is unclear how obesity may directly affect the mechanical loading environment of the knee joint, initiating or progressing joint degeneration. The objective of this study was to investigate the interacting role of obesity and moderate knee osteoarthritis presence on tibiofemoral contact forces and muscle forces within the knee joint during walking gait.

METHODS

Three-dimensional gait analysis was performed on 80 asymptomatic participants and 115 individuals diagnosed with moderate knee osteoarthritis. Each group was divided into three body mass index categories: healthy weight (body mass index<25), overweight (25≤body mass index≤30), and obese (body mass index>30). Tibiofemoral anterior-posterior shear and compressive forces, as well as quadriceps, hamstrings and gastrocnemius muscle forces, were estimated based on a sagittal plane contact force model. Peak contact and muscle forces during gait were compared between groups, as well as the interaction between disease presence and body mass index category, using a two-factor analysis of variance.

FINDINGS

There were significant osteoarthritis effects in peak shear, gastrocnemius and quadriceps forces only when they were normalized to body mass, and there were significant BMI effects in peak shear, compression, gastrocnemius and hamstrings forces only in absolute, non-normalized forces. There was a significant interaction effect in peak quadriceps muscle forces, with higher forces in overweight and obese groups compared to asymptomatic healthy weight participants.

INTERPRETATION

Body mass index was associated with higher absolute tibiofemoral compression and shear forces as well as posterior muscle forces during gait, regardless of moderate osteoarthritis presence or absence. The differences found may contribute to accelerated joint damage with obesity, but with the osteoarthritic knees less able to accommodate the high loads.

The Effect of Risk Factors on the Levels of Chemical Elements in the Tibial Plateau of Patients with Osteoarthritis following Knee Surgery

The aim of this study was to evaluate the aforementioned chemical elements in tibial plateau samples obtained during knee arthroplasty. The gender-specific analysis of chemical element levels in the bone samples revealed that there were statistically significant differences in the concentration of Pb and Se/Pb ratio. The contents of elements in the tibial plateau in the patients with osteoarthritis (OA) can be arranged in the following descending order: F(-) > K > Zn > Fe > Sr > Pb > Mn > Se > Cd > THg. We observed statistical significant effects of environmental factors including smoking, seafood diet, and geographical distribution on the levels of the elements in tibial bone. Significant positive correlation coefficients were found for the relationships K-Cd, Zn-Sr, Zn-F(-), THg-Pb, Pb-Cd, Se-Se/Pb, Se-Se/Cd, Se/Pb-Se/Cd, Pb-Cd/Ca, Cd-Cd/Ca, and F(-)-F(-)/Ca·1000. Significant negative correlations were found for the relationships THg-Se/Pb, Pb-Se/Pb, Cd-Se/Pb, K-Se/Cd, Pb-Se/Cd, Cd-Se/Cd, THg-Se/THg, Pb-Se/THg, Se-Pb/Cd, Zn-Cd/Ca, and Se/Cd-Cd/Ca. The results reported here may provide a basis for establishing reference values for the tibial plateau in patients with OA who had undergone knee replacement surgery. The concentrations of elements in the bone with OA were determined by age, presence of implants, smoking, fish and seafood diet, and sport activity.

Cartilage lesions and ankle osteoarthrosis: review of the literature and treatment algorithm

The main etiology of ankle osteoarthrosis is post-traumatic and its prevalence is highest among young individuals. Thus, this disease has a great socioeconomic impact and gives rise to significant losses of patients' quality of life. The objective of its treatment is to eliminate pain and keep patients active. Therefore, the treatment should be staged according to the degree of degenerative evolution, etiology, joint location, systemic condition, bone quality, lower-limb alignment, ligament stability and age. The treatment algorithm is divided into non-surgical therapeutic methods and options for surgical treatment. Joint preservation, joint replacement and arthrodesis surgical procedures have precise indications. This article presents a review on this topic and a proposal for a treatment algorithm for this disease.

Osteochondral defects of the talus: a novel animal model in the goat

Osteochondral defects of the talus pose a difficult therapeutic challenge. An experimental animal model of the ankle joint is not available. The aim of this study was to test a newly developed animal model for osteochondral defects of the ankle in vivo. Osteochondral defects were created in the talus of goat hind legs using a posterolateral surgical approach. The defects were filled with either autologous cancellous bone or donor demineralized bone matrix or left empty as control. After 12 weeks of healing, the specimens were analyzed with radiography, macroscopy, microcomputed tomography, histology, histomorphometry, and fluorescence microscopy. It was possible to create a standardized defect in each talus. The implanted material remained in place. The analyses showed that most bony tissue was generated in the defects filled with autologous bone and least in the control defects. Our findings show that a standard osteochondral defect can be created in the talus by a relatively simple procedure in a large animal that allows qualitative and quantitative evaluation. The model can be used in future experiments to investigate alternative treatment methods before they are introduced into clinical practice.

Correlation of intra-articular ankle pathology with cytokine biomarkers and matrix degradation products

BACKGROUND

Articular cartilage degeneration is mediated by inflammatory cytokines and fragments of structural matrix proteins. Few studies have examined the role of these biomarkers in intra-articular pathology of the ankle.

METHODS

Four groups of patients with increasing ankle pathology were enrolled. Group 1 included controls with no pain who underwent unrelated forefoot surgery. Group 2 included patients undergoing arthroscopy with intraoperative mild chondrosis. Group 3 included patients undergoing arthroscopy with moderate/severe chondrosis, osteochondral lesions, impingement, or loose bodies. Group 4 included positive controls with severe arthrosis undergoing ankle arthrodesis/arthroplasty. Ankle fluid was obtained by intra-articular aspiration and was assayed for IL-6, IFN-γ, MCP, MIP-1β, and fibronectin-aggrecan complex (FAC), a matrix-degradation marker. There were 36 patients total, 21 males and 15 females with a mean age 45 (±16; range 18 to 76) years and a mean VAS for pain of 4.7 (±3.5; range 0 to 9). In groups 1 through 4, there were 11, 6, 15 and 4 patients respectively.

RESULTS

The mean values of MCP-1 were 49.8 (±8.0) for minimal pathology and 133.9 (±33.0) for substantial pathology (pg/ml). The mean values of the FAC were 2.83 (±1.16) for minimal pathology and 9.62 (±2.23) for substantial pathology (optical density at 450 nm). The groups differed significantly in age, preoperative VAS, FAC, IL-6, and MCP-1 (p<0.05).

CONCLUSION

There are differences in FAC and MCP-1 with increasing grades of severity of intra-articular pathology.

CLINICAL RELEVANCE

These tests may play a role in determining the necessity for arthroscopy or intra-articular procedures in equivocal candidates.

MR imaging of the articular cartilage of the knee and ankle

Cartilage abnormalities in the knee and ankle are a common source of pain and are often difficult to diagnose clinically or radiographically. MR imaging is a valuable tool for diagnosing and characterizing cartilage lesions of both the knee and ankle. An understanding of the appearance of cartilage, and an understanding of how and when to report cartilage injury in the knee and ankle based on current grading systems allows the radiologist to provide the most helpful reports to referring clinicians. This article presents the range of cartilage pathologies in the knee and ankle and provides clinically relevant guidelines.

Effects of in vivo exercise on ankle cartilage deformation and recovery in healthy volunteers: an experimental study

OBJECTIVE

To monitor ankle cartilage 3D volume changes after in vivo exercise and during recovery.

METHOD

Based on 3D MRI, 3D volumes of talar and tibial cartilage were calculated before and after 30 bilateral knee bends in 12 healthy volunteers. 3D volumes were calculated at five time points (one pre- and four post-scans) determining deformation and recovery for both cartilage plates of interest. Post-scans ran immediately after the exercise and were repeated according to a 15 min interval. 3D volumes were subjected to repeated measures GLM. Additionally, relative surface area use during deformation was compared between plates using a Wilcoxon Signed Ranks test and its correlation with deformation was investigated using Spearman's rho.

RESULTS

Mean 3D volume change percentages for talar cartilage after the exercise were: -10.41%, -8.18%, -5.61% and -3.90%. For tibial cartilage mean changes were: -5.97%, -5.75%, +0.89% and +1.51%. For talar cartilage changes were significant, except following 30 min post-exercise. For tibial cartilage no changes were significant. At all time points, no significant differences in relative volume changes between both cartilage plates existed. Although no significant differences in relative surface area use between plates were revealed, a moderate to strong correlation with deformation existed.

CONCLUSION

Ankle cartilage endures substantial deformation after in vivo loading that was restored within 30 min for the talus. Overall cartilage contact area involvement might be associated with cartilage quality maintenance in the upper ankle. Talar cartilage is suggested to play a critical role in intra-articular shock attenuation when compared to tibial cartilage.

Human ankle cartilage deformation after different in vivo impact conditions

Recently, the general finding of increased ankle cartilage stiffness to loading has been challenged, suggesting the need for the investigation of different in vivo loading conditions. Therefore, the objectives of the present study were to determine ankle (talar) cartilage deformation after in vivo loading using 3D volume change calculation and to establish any difference in volume change between four weight-bearing exercises. The four exercises represented increasing impact (bilateral knee bends <unilateral knee bends <drop jumps) as well as two types of loading: dynamic and static loading (i.e. unilateral knee bends and unilateral static stance). Based on MRI, 3D reconstructions of talar cartilage were generated to determine 3D volumes before and after four exercises in 13 healthy subjects (bilateral and unilateral knee bends, static unilateral stance, drop jumps). Mean talar deformation (volume decrease) was 8.3% after bilateral knee bends (P = 0.001), 7.7% after unilateral knee bends (P = 0.020), 14.6% after unilateral static stance (P < 0.001), 12.5% after drop jumps (P = 0.001). Statistical analysis also revealed deformation to be significantly higher after unilateral static stance than after unilateral knee bends (P = 0.017). These results suggest that talar cartilage endures substantial deformation during in vivo loading characterized by more deformation (i.e. higher volume change) after static than after dynamic loading.

Treatment of ankle osteoarthritis: arthrodesis versus total ankle replacement

While ankle arthrodesis has remained the gold standard treatment for symptomatic primary, secondary, and posttraumatic ankle arthritis, more recently, total ankle replacement (TAR) has seen considerable improvement in terms of biomechanics, function, and complication rates. However, while in the long-term degeneration of the adjacent joints is almost always found on radiographs after ankle arthrodesis, the longevity of TAR is still insufficient and does not match that of total knee and hip joints. The current review article focuses on the treatment of ankle arthritis by means of arthrodesis and TAR.

Use of stem cells in the biological repair of articular cartilage

IMPORTANCE OF THE FIELD

Articular cartilage is avascular, aneural, and renowned for its poor capacity to repair after damage. For decades scientists and clinicians have deliberated over the potential to repair or regenerate articular cartilage and to date many techniques have been used in an attempt to create the best possible repair tissue.

AREAS COVERED IN THIS REVIEW

This review article summarises surgical interventions that have been developed since the late 1940's; covering conservative strategies, invasive techniques and touching upon latest advancements involving stem cells and tissue engineering.

WHAT WILL THE READER GAIN

The reader will gain a sound understanding into the history and background of strategies that have developed in attempts to reverse clinical symptoms of damaged or diseased articular cartilage. The article provides an insight into the plethora of potential repair mechanisms, and reviews future developments involving stem cells and biomaterials.

TAKE HOME MESSAGE

Although work is still in its infancy, the use of stem cells in the biological repair of articular cartilage provides a promising outlook onto future developments; advancing from strategies and techniques that are already in use.