Radiographic joint space narrowing and histologic changes in a rabbit meniscectomy model of early knee osteoarthrosis

Micromolding-based encapsulation of mesenchymal stromal cells in alginate for intraarticular injection in osteoarthritis

Osteoarthritis (OA) is an inflammatory joint disease that affects cartilage, subchondral bone, and joint tissues. Undifferentiated Mesenchymal Stromal Cells are a promising therapeutic option for OA due to their ability to release anti-inflammatory, immuno-modulatory, and pro-regenerative factors. They can be embedded in hydrogels to prevent their tissue engraftment and subsequent differentiation. In this study, human adipose stromal cells are successfully encapsulated in alginate microgels via a micromolding method. Microencapsulated cells retain their in vitro metabolic activity and bioactivity and can sense and respond to inflammatory stimuli, including synovial fluids from OA patients. After intra-articular injection in a rabbit model of post-traumatic OA, a single dose of microencapsulated human cells exhibit properties matching those of non-encapsulated cells. At 6 and 12 weeks post-injection, we evidenced a tendency toward a decreased OA severity, an increased expression of aggrecan, and a reduced expression of aggrecanase-generated catabolic neoepitope. Thus, these findings establish the feasibility, safety, and efficacy of injecting cells encapsulated in microgels, opening the door to a long-term follow-up in canine OA patients.

Study on feasibility of the partial meniscal allograft transplantation

Since the meniscus is an important stabilizing structure of the knee joint and has a significant role in load-bearing and shock absorption, so the complete structural and functional reconstructions of the teared menisci should be done not only after partial meniscectomy but also post total meniscectomy. So far, animal experiments and good clinical practice have showed that TMAT after total meniscectomy has partially solved the problem of structural and functional reconstructions after total meniscectomy. However, partial meniscectomy will also lead to accelerated knee degeneration, and its proportion is much higher than that of patients with total meniscectomy. Herein, the feasibility of PMAT after partial meniscectomy was investigated for the first time by using the 40% posterior horn meniscectomy model of the medial meniscus in Beagle dogs, and also for the first time, TMAT group and the total meniscectomy group were used as control groups. Compared with the TMAT, the transcriptomics evaluation, scanning electron microscope observation, histological regeneration and structure, biomechanical property, inflammation environment, and the knee function post PMAT were more similar to that of normal meniscus was first reported. This study provides a PMAT scheme with clinical translational value for the complete structural and functional reconstruction of the patients with partial meniscectomy and fills the gap in the field of teared meniscus therapy on the basis of quite well clinical applications of the meniscus repair and the TMAT.

Time to Achievement of Clinically Significant Outcomes After Isolated Arthroscopic Partial Meniscectomy: A Multivariate Analysis

Purpose

To define the time required to achieve the minimally clinically important difference (MCID), substantial clinical benefit (SCB) and patient acceptable symptomatic state (PASS) for isolated arthroscopic partial meniscectomy (APM), and define preoperative and intraoperative factors that predict both early and late achievement of the stated metrics.

Methods

Patients who underwent isolated APM between 2014 and 2017 were retrospectively included. Patients without preoperative and 6-month patient-reported outcome measure scores, revision procedures, and significant concomitant procedures were excluded. The MCID, SCB, and PASS were calculated for knee-based patient-reported outcome measure scores using receiver operating curve analysis. Kaplan-Meier survival analysis established the time required to achieve MCID, SCB and PASS. Hazard ratios from multivariate Cox regression allowed for the isolation of demographic and intraoperative factors predictive of the delayed time required to achieve MCID, SCB and PASS.

Results

A total of 126 patients (42.86% female, age: 48.9 ± 12.4 years) were included. Overall achievement rates ranged between 73.0% and 89.7% for MCID, 43.7% and 68.2% for SCB, and 50.8% and 68.3% for PASS. Median achievement time for MCID was 5.68-5.78 months, 5.73-6.05 months for SCB and 6.54-7.72 months for PASS. Multivariate Cox regression identified older age, workers' compensation status, diabetes, and various tear types (i.e., longitudinal, transverse, bucket handle, complex) as predictors of early clinically significant outcome achievement (hazard ratio: 1.02-24.72), whereas subsequent steroid injection, higher preoperative scores and root and flap tears predicted delays in clinically significant outcome achievement (hazard ratio: 0.12-0.99).

Conclusions

The majority of patients undergoing APM achieve benefit within 6 months of surgery, with diminishing proportions at later timepoints. Important factors for consideration of the the timeline of achieving clinically significant outcome include age, diabetes, workers' compensation, preoperative score, and tear type. The timeline for achieving improvement that was established by this study may aid in setting patient expectations and designing future outcome studies involving APM.

Study design

Level IV, Therapeutic Case Series.

Effects of insulin-like growth factor 1 and basic fibroblast growth factor on the morphology and proliferation of chondrocytes embedded in Matrigel in a microfluidic platform

An integrated microfluidic device was utilized in the present study to investigate the morphology and proliferation of rabbit articular chondrocytes embedded in Matrigel in the presence of insulin-like growth factor 1 (IGF-1) and/or basic fibroblast growth factor (bFGF). The microfluidic device was composed of two parallel channels and a central perfusion-based three-dimensional cell culture module. The rabbit chondrocytes were cultured for 2 weeks at series of concentration gradients of IGF-1 and/or bFGF, which were generated through a diffusion process. At the end of the experiment, the morphology and quantity of cells were measured. Since high expression of collagen II is essential to the function of hyaline cartilage, immunofluorescent images of collagen II expression prior to and after the experiments were gathered for each group. The mean fluorescence intensity ratio (MIR) of collagen II in each group was calculated. The MIRs of collagen II in chondrocytes treated with IGF-1 ranged from 0.6-0.81, those in the cells treated with bFGF ranged from 0.47-0.52, and those in cells treated with a combination of IGF-1 and bFGF ranged from 0.63-0.83. Chondrocyte aggregations were observed in the group treated with 75-100 ng/ml IGF-1 (3.46-fold proliferation ratio). Similarly, a 3.83-fold proliferation ratio was identified in chondrocytes treated with 2.5-5.0 ng/ml bFGF. The group treated with 50-75 ng/ml IGF-1 and 2.5-5.0 ng/ml bFGF exhibited the optimum increase in proliferation (4.83-fold proliferation ratio). The microfluidic device used in the present study can be easily adapted to investigate other growth factors at any concentration gradient. In addition, parallel experiments can be performed simultaneously with a small quantity of cells, making it an attractive platform for the high-throughput screening of cell culture parameters. This platform will aid in the optimization of culture conditions for the in vitro expansion of chondrocytes while maintaining their in vivo morphology, which will improve autologous chondrocyte implantation capabilities for the treatment of cartilage injury.

Safety Studies for Use of Adipose Tissue-Derived Mesenchymal Stromal/Stem Cells in a Rabbit Model for Osteoarthritis to Support a Phase I Clinical Trial

Adipose‐derived mesenchymal stem cells (AMSCs) offer potential as a therapeutic option for clinical applications in musculoskeletal regenerative medicine because of their immunomodulatory functions and capacity for trilineage differentiation. In preparation for a phase I clinical trial using AMSCs to treat patients with osteoarthritis, we carried out preclinical studies to assess the safety of human AMSCs within the intra‐articular joint space. Culture‐expanded human AMSCs grown in human platelet‐lysate were delivered via intra‐articular injections into normal healthy rabbit knees and knees at risk for the development of osteoarthritis after bilateral medial anterior hemimeniscectomy. Treatment outcomes and safety were evaluated by assessing the general health, function, and behavior of the animals. Joint tissues were analyzed by x‐ray, magnetic resonance imaging, and histopathology. Intra‐articular AMSC therapy was well tolerated in this study. We did not observe adverse systemic reactions, nor did we find evidence of damage to intra‐articular joint tissues. Thus, the data generated in this study show a favorable safety profile for AMSCs within the joint space in support of a phase I clinical trial evaluating the clinical utility of AMSCs to treat osteoarthritis. Stem Cells Translational Medicine2017;6:910–922

Clinical joint inactivity predicts structural stability in patients with established rheumatoid arthritis

OBJECTIVES

Clinical joint activity is a strong predictor of joint damage in rheumatoid arthritis (RA), but progression of damage might increase despite clinical inactivity of the respective joint (silent progression). The aim of this study was to evaluate the prevalence of silent joint progression, but particularly on the patient level and to investigate the duration of clinical inactivity as a marker for non-progression on the joint level.

METHODS

279 patients with RA with any radiographic progression over an observational period of 3-5 years were included. We obtained radiographic and clinical data of 22 hand/finger joints over a period of at least 3 years. Prevalence of silent progression and associations of clinical joint activity and radiographic progression were evaluated.

RESULTS

120 (43.0%) of the patients showed radiographic progression in at least one of their joints without any signs of clinical activity in that respective joint. In only 7 (5.8%) patients, such silent joint progression would go undetected, as the remainder had other joints with clinical activity, either with (n=84; 70.0%) or without (n=29; 24.2%) accompanying radiographic progression. Also, the risk of silent progression decreases with duration of clinical activity.

CONCLUSIONS

Silent progression of a joint without accompanying apparent clinical activity in any other joint of a patient was very rare, and would therefore be most likely detected by the assessment of the patient. Thus, full clinical remission is an excellent marker of structural stability in patients with RA, and the maintenance of this state reduces the risk of progression even further.

Qualitative and quantitative measurement of the anterior and posterior meniscal root attachments of the New Zealand white rabbit

BACKGROUND

The purpose of this study was to quantify the meniscal root anatomy of the New Zealand white rabbit to better understand this animal model for future in vitro and in vivo joint degeneration studies.

METHODS

Ten non-paired fresh frozen New Zealand white rabbit knee stifle joints were carefully disarticulated for this study. Measurements were made for all bony landmarks and ligamentous structure attachment sites on the tibial plateau. The following soft tissue structures were consistently identified in the rabbit stifle joint: the anterior root attachment of the lateral meniscus, the anterior root attachment of the medial meniscus, the anterior cruciate ligament, the posterior root attachment of the medial meniscus, the ligament of Wrisberg, the posterior cruciate ligament, and the posterior meniscotibial ligament. The following bony landmarks were consistently identified: the extensor digitorum longus groove, the medial tibial eminence, the center of the tibial tuberosity, and the lateral tibial eminence.

RESULTS

The center of the anterior cruciate ligament and the medial tibial eminence apex were found to be 3.4 ± 0.3 mm (2.9-3.6) and 6.1 ± 0.6 mm (5.1-7.0) respectively from the center of the medical anterior root attachment. The center of the anterior cruciate ligament and the lateral tibial eminence apex were found to be 2.1 ± 0.5 mm (1.2-2.7) and 7.0 ± 0.6 mm (6.4-8.2) respectively from the center of the lateral anterior root attachment. The center of the posterior cruciate ligament and the medial tibial eminence apex were found to be 2.0 ± 0.7 mm (0.5-2.6) and 1.8 ± 0.4 mm (1.2-2.4) respectively from the center of the medial posterior root attachment.

CONCLUSIONS

This study augments our understanding of the comparative anatomy of the rabbit stifle joint. This information will be useful for future biomechanical, surgical, and in vitro studies utilizing the rabbit stifle as a model for human knee joint degenerative diseases.

Animal models of osteoarthritis: classification, update, and measurement of outcomes

Osteoarthritis (OA) is one of the most commonly occurring forms of arthritis in the world today. It is a debilitating chronic illness causing pain and immense discomfort to the affected individual. Significant research is currently ongoing to understand its pathophysiology and develop successful treatment regimens based on this knowledge. Animal models have played a key role in achieving this goal. Animal models currently used to study osteoarthritis can be classified based on the etiology under investigation, primary osteoarthritis, and post-traumatic osteoarthritis, to better clarify the relationship between these models and the pathogenesis of the disease. Non-invasive animal models have shown significant promise in understanding early osteoarthritic changes. Imaging modalities play a pivotal role in understanding the pathogenesis of OA and the correlation with pain. These imaging studies would also allow in vivo surveillance of the disease as a function of time in the animal model. This review summarizes the current understanding of the disease pathogenesis, invasive and non-invasive animal models, imaging modalities, and pain assessment techniques in the animals.

The benefits and limitations of animal models for translational research in cartilage repair

Much research is currently ongoing into new therapies for cartilage defect repair with new biomaterials frequently appearing which purport to have significant regenerative capacity. These biomaterials may be classified as medical devices, and as such must undergo rigorous testing before they are implanted in humans. A large part of this testing involves in vitro trials and biomechanical testing. However, in order to bridge the gap between the lab and the clinic, in vivo preclinical trials are required, and usually demanded by regulatory approval bodies. This review examines the in vivo models in current use for cartilage defect repair testing and the relevance of each in the context of generated results and applicability to bringing the device to clinical practice. Some of the preclinical models currently used include murine, leporine, ovine, caprine, porcine, canine, and equine models. Each of these has advantages and disadvantages in terms of animal husbandry, cartilage thickness, joint biomechanics and ethical and licencing issues. This review will examine the strengths and weaknesses of the various animal models currently in use in preclinical studies of cartilage repair.

The quality of healing: articular cartilage

Articular cartilage lacks an intrinsic capacity for self-repair, and once damaged, it never heals. This creates an opportunity for surgical intervention, whether to stimulate a healing response that results in the formation of a lower-quality fibrocartilaginous scar or formal cartilage repair in the form of cartilage transplants. This article will review the nature of cartilage injury and discuss indications and techniques for repair.

Tibiofemoral loss of contact area but no changes in peak pressures after meniscectomy in a Lapine in vivo quadriceps force transfer model

PURPOSE

The menisci are thought to modulate load transfer and to absorb shocks in the knee joint. No study has experimentally measured the meniscal functions in the intact, in vivo joint loaded by physiologically relevant muscular contractions.

METHODS

Right knee joints of seven New Zealand white rabbits were loaded using isometric contractions of the quadriceps femoris muscles controlled by femoral nerve stimulation. Isometric knee extensor torques at the maximal and two submaximal force levels were performed at knee angles of 70°, 90°, 110°, and 130°. Patellofemoral and tibiofemoral contact areas and pressure distributions were measured using Fuji Presensor film inserted above and below the menisci and also with the menisci removed.

RESULTS

Meniscectomy was associated with a decrease in tibiofemoral contact area ranging from 30 to 70% and a corresponding increase in average contact pressures. Contact areas measured below the menisci were consistently larger than those measured on top of the menisci. Contact areas in the patellofemoral joint (PFJ), and peak pressures in tibiofemoral and PFJs, were not affected by meniscectomy. Contact areas and peak pressures in all joints depended crucially on knee joint angle and quadriceps force: The more flexed the knee joint was, the larger were the contact areas and the higher were the peak pressures.

CONCLUSIONS

In agreement with the literature, removal of the menisci was associated with significant decreases in tibiofemoral contact area and corresponding increases in average contact pressures, but surprisingly, peak pressures remained unaffected, indicating that the function of the menisci is to distribute loads across a greater contact area.

Evaluation of meniscal mechanics and proteoglycan content in a modified anterior cruciate ligament transection model

Post-traumatic osteoarthritis (PTOA) develops as a result of traumatic loading that causes tears of the soft tissues in the knee. A modified transection model, where the anterior cruciate ligament (ACL) and both menisci were transected, was used on skeletally mature Flemish Giant rabbits. Gross morphological assessments, elastic moduli, and glycosaminoglycan (GAG) coverage of the menisci were determined to quantify the amount of tissue damage 12 weeks post injury. This study is one of the first to monitor meniscal changes after inducing combined meniscal and ACL transections. A decrease in elastic moduli as well as a decrease in GAG coverage was seen.

Magnetic resonance imaging of osteophytic, chondral, and subchondral structures in a surgically-induced osteoarthritis rabbit model

OBJECTIVE

This study aimed to assess changes in osteophytic, chondral, and subchondral structures in a surgically-induced osteoarthritis (OA) rabbit model in order to correlate MRI findings with the macroscopic progress of OA and to define the timepoint for disease status in this OA model.

METHODS

The OA model was constructed by surgery in thirty rabbits with ten normal rabbits serving as controls (baseline). High-resolution three-dimensional MRI using a 1.5-T coil was performed at baseline, two, four, and eight weeks post-surgery. MRIs of cartilage lesions, subchondral bone lesions, and osteophyte formations were independently assessed by two blinded radiologists. Ten rabbits were sacrificed at baseline, two, four, and eight weeks post-surgery, and macroscopic evaluation was independently performed by two blinded orthopedic surgeons.

RESULTS

The signal intensities and morphologies of chondral and subchondral structures by MRI accurately reflected the degree of OA. Cartilage defects progressed from a grade of 0.05-0.15 to 1.15-1.30 to 1.90-1.97 to 3.00-3.35 at each successive time point, respectively (p<0.05). Subchondral bone lesions progressed from a grade of 0.00 to 0.78-0.90 to 1.27-1.58 to 1.95-2.23 at each successive time point, respectively (p = 0.000). Osteophytes progressed from a size (mm) of 0.00 to 0.87-1.06 to 1.24-1.87 to 2.21-3.21 at each successive time point, respectively (p = 0.000).

CONCLUSIONS

Serial observations revealed that MRI can accurately detect the progression of cartilage lesions and subchondral bone edema over an eight-week period but may not be accurate in detecting osteophyte sizes. Week four post-surgery was considered the timepoint between OA-negative and OA-positive status in this OA model. The combination of this OA model with MRI evaluation should provide a promising tool for the pre-clinical evaluation of new disease-modifying osteoarthritis drugs.

Dedicated cone-beam CT system for extremity imaging

PURPOSE

To provide initial assessment of image quality and dose for a cone-beam computed tomographic (CT) scanner dedicated to extremity imaging.

MATERIALS AND METHODS

A prototype cone-beam CT scanner has been developed for imaging the extremities, including the weight-bearing lower extremities. Initial technical assessment included evaluation of radiation dose measured as a function of kilovolt peak and tube output (in milliampere seconds), contrast resolution assessed in terms of the signal difference-to-noise ratio (SDNR), spatial resolution semiquantitatively assessed by using a line-pair module from a phantom, and qualitative evaluation of cadaver images for potential diagnostic value and image artifacts by an expert CT observer (musculoskeletal radiologist).

RESULTS

The dose for a nominal scan protocol (80 kVp, 108 mAs) was 9 mGy (absolute dose measured at the center of a CT dose index phantom). SDNR was maximized with the 80-kVp scan technique, and contrast resolution was sufficient for visualization of muscle, fat, ligaments and/or tendons, cartilage joint space, and bone. Spatial resolution in the axial plane exceeded 15 line pairs per centimeter. Streaks associated with x-ray scatter (in thicker regions of the patient--eg, the knee), beam hardening (about cortical bone--eg, the femoral shaft), and cone-beam artifacts (at joint space surfaces oriented along the scanning plane--eg, the interphalangeal joints) presented a slight impediment to visualization. Cadaver images (elbow, hand, knee, and foot) demonstrated excellent visibility of bone detail and good soft-tissue visibility suitable to a broad spectrum of musculoskeletal indications.

CONCLUSION

A dedicated extremity cone-beam CT scanner capable of imaging upper and lower extremities (including weight-bearing examinations) provides sufficient image quality and favorable dose characteristics to warrant further evaluation for clinical use.

Theoretical prediction of ultrasound elastography for detection of early osteoarthritis

Ultrasound elastography could be used as a new noninvasive technique for detecting early osteoarthritis. As the first critical step, this study theoretically predicted the excitation power and the measurement errors in detecting cartilage detect. A finite element model was used to simulate wave propagation of elastography in the cartilage. The wave was produced by a force F, and the wave speed C was calculated. The normal cartilage model was used to define the relationship between the wave speed and elastic modulus. Various stiffness values were simulated. F = 10 N with a duration of 0.5 ms was required for having measurable deformation (10 μm) at the distal site. The deformation had a significant rise when the wave crossed the defect. The relationship between the wave speed and elastic parameters was found as C = 1.57 × (E)/(2 × ρ(1+μ)))^1/2, where E was the elastic modulus, μ was Poisson's ratio, and ρ was the density. For the simulated defect with an elastic modulus of 7 MPa which was slightly stiffer than the normal cartilage, the measurement error was 0.1 MPa. The results suggested that, given the simulated conditions, this new technique could be used to detect the defect in early osteoarthritis.

Replication of chronic abnormal cartilage loading by medial meniscus destabilization for modeling osteoarthritis in the rabbit knee in vivo

Medial meniscus destabilization (MMD) is a surgical insult technique for modeling osteoarthritis (OA) by replicating chronic abnormal cartilage loading in animal joints in vivo. The present study aimed to characterize the immediate biomechanical effects (ex vivo) and short-term histological consequences (in vivo) of MMD in the rabbit knee. In a compressive loading test, contact stress distribution in the medial compartment was measured in eight cadaver rabbit knees, initially with all major joint structures uninjured (Baseline), after MMD, and finally after total medial meniscectomy (TMM). Similarly, the effects on sagittal joint stability were determined in an anterior-posterior drawer test. These biomechanical (ex vivo) data indicated that both MMD and TMM caused significant (p < 0.001), distinct (>1.5-fold) elevation of peak local contact stress in the medial compartment, while leaving whole-joint stability nearly unchanged. Histological consequences in vivo were assessed in a short-term (8-week) survival series of MMD or TMM (five animals for each group), and both caused moderate cartilage degeneration in the medial compartment. The MMD insult, which is feasible through posterior arthrotomy alone, is as effective as TMM for modeling injurious-level chronic abnormal cartilage loading in the rabbit knee medial compartment in vivo, while minimizing potential confounding effects from whole-joint instability.

Ultrasonographic evaluation of the femoral cartilage thickness after unilateral arthroscopic partial meniscectomy

PURPOSE

To assess the distal femoral cartilage after unilateral arthroscopic partial meniscectomy and to explore the relationship between cartilage thickness and various disease-/surgery-related parameters.

METHODS

Eighty-nine patients (42 M, 47 F) who had undergone arthroscopic partial meniscectomy surgery were evaluated. Ultrasonographic distal femoral cartilage thicknesses were measured with a 5-13-MHz linear probe (General Electric, Logiq P5) on mid-points of the lateral condyle, intercondylar notch and medial condyle of operated and non-operated knees by a physician blinded to patients' data. Demographic features, duration after surgery, type of meniscal tear and site of meniscectomy were recorded.

RESULTS

Mean age of the patients was 51.8 ± 12.8 years (range 18-88). Mean body mass index was 29.4 ± 4.4 kg/m2 (range 18-38). Overall, in patients with degenerative meniscal tears, femoral cartilage thicknesses pertaining to all the three measured sites (lateral, intercondylar and medial) were found to be decreased in the operated knees when compared with those of the non-operated knees (p = 0.004, p = 0.003, p = 0.041, respectively), whereas in patients with non-degenerative tears, this decrease was significant only in the intercondylar area (p = 0.038). When patients were grouped according to the duration (months) after their surgery (≤36, 37-48 and ≥49), cartilage thickness was similar between both knees in the first group, decreased at the lateral condyle (p = 0.008) and intercondylar area (p = 0.049) in the second group and decreased at all three sites (lateral, intercondylar and medial) in the third group (p = 0.015, p = 0.005 and p = 0.008, respectively).

CONCLUSION

These findings would be considered as unfavourable with respect to weight-bearing, and thus, conservative measures to support relevant joints would strongly be kept in mind during clinical practice. Lastly, ultrasonography may be a convenient alternative imaging method for the evaluation of short- and medium-term cartilage loss in patients with arthroscopic partial meniscectomy.

LEVELS OF EVIDENCE

III.

Effect of combined traumatic impact and radial transection of medial meniscus on knee articular cartilage in a rabbit in vivo model

PURPOSE

The purpose of this study was to test the hypothesis that combined meniscectomy and traumatic impact accelerate early degeneration of articular cartilage in the knee versus meniscectomy alone.

METHODS

A previously published in vivo rabbit cartilage impact model was used combined with radial transection of the medial meniscus posterior horn versus meniscal transection alone. Rabbits were killed 3 months after surgery. Quantitative histologic analysis of the articular cartilage proteoglycan depth and glycosaminoglycan (GAG) fraction was performed at the site of impact on the posterior femoral condyle (PFC) and at the distal femoral condyle (DFC) overlying the meniscectomy in the surgical knee and the contralateral control knee.

RESULTS

The articular cartilage in the knees that underwent isolated meniscectomy did not differ significantly from the contralateral control knees for any measured value. The knees with a combined insult had a lower GAG fraction (P = .03) at the PFC and a greater depth of proteoglycan loss at both the PFC (P = .02) and the DFC (P = .04) versus contralateral controls. Compared with meniscectomy alone, the combined-insult knees had a greater depth of proteoglycan loss at the DFC (P = .005).

CONCLUSIONS

On the basis of early results using GAG fraction and proteoglycan depth, combined traumatic impact and meniscectomy are more damaging to articular cartilage than meniscectomy alone.

CLINICAL RELEVANCE

A knee with a combination of meniscal injury and articular cartilage impact may be at particularly high risk for early joint degeneration.

A proposed model of naturally occurring osteoarthritis in the domestic rabbit

Osteoarthritis affects one in eight American adults over the age of 25 y and is a leading cause of chronic disability in the US. Translational research to investigate treatments for this naturally occurring joint disease requires an appropriate animal model. The authors conducted a retrospective study to assess the potential of naturally occurring osteoarthritis in the domestic rabbit as a model of the human disease. Analysis of radiographic images showed that the presence and severity of osteoarthritis were significantly influenced by both age and body weight. The most commonly affected joints were the knee and the hip. The findings reported here suggest that the rabbit is an excellent model of spontaneously arising osteoarthritis that may be useful in translational research pertaining to the human disease.

Meniscus replacement using synthetic materials

The meniscus plays a critical role in load transmission, stability and energy dissipation in the knee joint. Loss of the meniscus leads to joint degeneration and osteoarthritis. An increased understanding of the degenerative changes that occur after meniscectomy made clear that it is beneficial to save as much meniscal tissue as possible. Meniscal repair has become a standard procedure, and partial resection of damaged menisci should be performed as sparingly as possible. However, not all damaged menisci can be treated by partial resection or by repair, making a total meniscectomy inevitable. In these cases, replacement of the resected meniscal tissue by an implant might avoid the articular cartilage degeneration. Different types of meniscal substitutes, such as allografts, collagen, permanent synthetic scaffolds, and biodegradable scaffolds, have been used in experimental and clinical studies. This review highlights the research on these meniscal substitutes and shows that current research is mainly focused on a biological tissue-engineering approach either with or without additional cell-seeding techniques.

The influence of nonanatomical insertion and incongruence of meniscal transplants on the articular cartilage in an ovine model

BACKGROUND

Adequate size matching and anatomically correct positioning must be recognized as essential factors influencing the outcome of meniscal transplantation.

HYPOTHESIS

Nonanatomical insertion and incongruence of meniscal transplants has an influence on the development of degenerative changes.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten female sheep were used for this animal study. Both knees (N = 20) were divided into 3 groups, subjected to either meniscectomy (group I; n = 10), to a medial meniscal autograft transplantation with a nonanatomical insertion of the anterior and posterior horn (group II; n = 5), or a meniscal autograft transplantation from the opposite knee as an incongruent meniscal autograft (group III; n = 5). After 6 months, radiographic (Fairbank's criteria), macroscopic (Jackson score), and histological evaluation by light microscopy (Mankin score) and scanning electron microscopy of the articular cartilage was performed.

RESULTS

All applied evaluation methods demonstrated that nonanatomical insertion of meniscal transplants resulted in the highest amount of degenerative cartilage changes. The histological assessment even revealed a significantly enlarged cartilage damage for the non-anatomic-positioned meniscal transplants in relation to the meniscectomized knees. Furthermore, the incongruent meniscal transplants demonstrated a significantly better cartilage situation than nonanatomically inserted meniscal transplants.

CONCLUSION

The histological evaluation demonstrated clearly that a nonanatomically inserted meniscal transplant leads to degenerative cartilage changes that are worse than that after meniscectomy.

CLINICAL RELEVANCE

Precise anatomic positioning is mandatory for the potential chondroprotective effect of meniscal transplants.

Relationships among measurements obtained by use of computed tomography and radiography and scores of cartilage microdamage in hip joints with moderate to severe joint laxity of adult dogs

OBJECTIVE

To evaluate correlations among measurements on radiographic and computed tomography (CT) images with articular cartilage microdamage in lax hip joints of dogs.

ANIMALS

12 adult mixed-breed hounds.

PROCEDURES

Pelvic CT and radiography were performed. Hip joints were harvested following euthanasia. Orthopedic Foundation for Animals (OFA) and PennHIP radiograph reports were obtained. Norberg angle (NA) and radiographic percentage femoral head coverage (RPC) were determined. Center-edge angle (CEA), horizontal toit externe angle (HTEA), ventral acetabular sector angle (VASA), dorsal acetabular sector angle (DASA), horizontal acetabular sector angle (HASA), acetabular index (AI), and CT percentage femoral head coverage (CPC) were measured on 2-dimensional CT images. Femoral head-acetabular shelf percentage was measured on sagittal 3-dimensional CT (SCT) and transverse 3-dimensional CT (TCT) images. Light microscopy was used to score joint cartilage. Relationships of OFA confirmation and PennHIP osteoarthritis scores with radiography, CT, and cartilage variables and relationships of cartilage scores with radiography and CT measurements were evaluated with Spearman rank correlations. Pearson correlation was used for relationships of distraction index (DI) with radiography, CT, and cartilage variables.

RESULTS

Significant relationships included PennHIP osteoarthritis score with cartilage score, CEA, HTEA, DASA, AI, CPC, and TCT; OFA confirmation score with cartilage score, NA, RPC, CEA, HTEA, DASA, AI, CPC, and TCT; cartilage score with NA, RPC, CEA, HTEA, DASA, HASA, AI, and TCT; and DI with cartilage score, CEA, HTEA, DASA, HASA, AI, and CPC.

CONCLUSIONS AND CLINICAL RELEVANCE

CT appeared to be a valuable imaging modality for predicting cartilage microdamage in canine hip joints.

Joint space narrowing after partial medial meniscectomy in the anterior cruciate ligament-intact knee

Osteoarthritis of the knee is common after total medial meniscectomy. In anterior cruciate ligament-intact knees, the reported outcomes of partial medial meniscectomy are variable. Radiographic assessment using a posteroanterior weight-bearing view is a reliable tool for detecting minor medial joint space narrowing, which may be an early sign of osteoarthritis. Studies that assessed the effect of partial medial meniscectomy found a low percentage of patients with >50% joint narrowing at 10 to 15 years after surgery. Digital radiography, using a posteroanterior weight-bearing view, is a highly sensitive method for observing minor joint space narrowing in the involved knee. A recent study showed that 88% of patients who underwent partial medial meniscectomy had joint space narrowing of <2 mm, and none had narrowing >or=2 mm, at a mean follow-up of 12 years. Subjective results after partial medial meniscectomy are favorable, with 88% to 95% of patients reporting good to excellent results.

Meniscus allograft transplantation: a current concepts review

Meniscus allotransplantation represents the biological solution for the symptomatic, meniscus-deficient patient who has not developed advanced osteoarthritis. A growing body of evidence suggests that pain relief and functional improvement may reliably be achieved at short- and medium-term follow-up, and even, in some cases, at long-term (>10 years) follow-up. Future research must address the issue of optimal timing of the procedure and whether meniscal transplantation results in demonstrable long-term benefits, especially with regard to protection of articular cartilage.

Meniscal allograft transplantation: a systematic review

Meniscal transplantation has become an accepted treatment option for selected symptomatic patients who have undergone a complete or near-complete meniscectomy. Basic and preliminary clinical studies suggest a meniscal allograft may replicate (though not completely) the shock-absorbing function of the normal meniscus to alleviate pain and provide measurable improvement in knee function. However, there is limited information on which to base crucial clinical decisions in treating the meniscectomized patient. I systematically explored available literature to address four general questions: Who is the ideal patient for a meniscal transplantation? What is the ideal method of graft sizing, preservation, and implantation? What is the accepted means of postoperative rehabilitation and timing of a return to athletic activities? And finally, what is the overall success rate of this procedure? This review of existing clinical trials revealed several crucial treatment principles for surgeons performing this procedure: (1) achieving or reestablishing normal knee alignment and stability; (2) implanting a size-matched, non-irradiated graft with secure fixation of the meniscal horns; and (3) ensuring patients return only to light sports activities to maximize the chances for graft survival. By following these principles, symptomatic improvement can be achieved in the majority of patients.

The influence of intraoperative pretensioning on the chondroprotective effect of meniscal transplants

BACKGROUND

Meniscal replacement has become more common in recent years. The meniscal transplant's ability to transfer load effectively depends on its ability to bear circumferential loading.

HYPOTHESIS

Intraoperative pretensioning on the meniscal transplant sutures has a positive influence on meniscal transplants' chondroprotective effect.

STUDY DESIGN

Controlled laboratory study.

METHODS

Thirty-six sheep were divided into 6 groups (n = 6), subjected to a sham operation (group A), a meniscectomy (group B), or a meniscal autograft using tag sutures with different levels of pretensioning (group C, 0 N; group D, 20 N; group E, 40 N; group F, 60 N). Macroscopic (International Cartilage Repair Society score) and histologic evaluations (Mankin score) of the articular cartilage were performed after 6 months.

RESULTS

Higher suture pretension (40 N, 60 N) resulted in less cartilage degeneration than in meniscectomized (P =.047; P =.036) and nonpretensioned (P =.028; P =.015) knees, with International Cartilage Repair Society scores of 1.63 +/- 0.57 and 1.66 +/- 0.51 in groups E and F, respectively, and scores of 2.40 +/- 0.27 and 2.68 +/- 0.46 observed after meniscectomy and meniscal transplantation with no pretensioning, respectively. Group F had a significantly better Mankin score of 6.66 +/- 2.15 (P =.05) compared with group D. Regarding criterion cells, trends toward less degeneration compared with meniscectomized and nonpretensioned knees (P = .054 and P =.055) were found. The coefficient of variation of the Mankin scores was greater than that of the International Cartilage Repair Society score. Group A had significantly better cartilage than all other groups.

CONCLUSION

Adequate intraoperative pretensioning has a significant influence on the chondroprotective effect of meniscal transplants but did not prevent the development of articular cartilage degeneration.

CLINICAL RELEVANCE

The results suggest that intraoperative pretensioning could improve the chondroprotective effect of meniscal transplantation.

Imaging osteoarthritis: Magnetic resonance imaging versus x-ray

Until recently, imaging evaluation of osteoarthritis has relied primarily on conventional radiography. Using radiography in clinical practice or clinical research, however, has been fraught with difficulty. Techniques for reproducibly acquiring serial radiographs of joints have improved considerably over the past several years. However, the greatest promise for advancing knowledge about osteoarthritis and its treatment lies in MRI and its unique ability to examine the joint as a whole organ. In contrast to conventional radiography, MRI can directly visualize the articular cartilage, synovium, menisci, and other intra-articular structures important to the functional integrity of joints. There have been considerable advances in MRI of articular cartilage in particular over the past several years. However, much of this has come from small cross-sectional studies. Larger, longitudinal studies are ongoing, and publications are just emerging. This paper reviews the current status of x-ray and MRI in osteoarthritis and points to where changes might be anticipated in the future.

Footwear alterations and bracing as treatments for knee osteoarthritis

PURPOSE OF REVIEW

The biomechanical aspects of gait and the impact of alignment have been recognized as important in the development and progression of knee osteoarthritis. Improving malalignment and altering the dynamic forces on the involved compartment of the knee during gait have the potential to improve the symptoms of knee osteoarthritis. This review examines the use of foot orthoses and knee braces to change the biomechanical forces on the knee joint and to reduce pain and improve function in patients with existing symptomatic knee osteoarthritis.

RECENT FINDINGS

Malalignment has been shown to have an impact on the development and progression of knee osteoarthritis. Patients with medial compartment knee osteoarthritis who have a visible varus thrust will also progress at a more rapid rate than patients without a varus thrust. Lateral wedge foot orthoses have been shown in biomechanical studies and clinical studies to reduce the load on the medial compartment and improve the symptoms of medial compartment knee osteoarthritis. Knee braces that stabilize the knee joint and provide a valgus stress have been shown to improve pain and function in patients with medial compartment knee osteoarthritis.

SUMMARY

The development of symptomatic knee osteoarthritis and the progression of joint space loss is in part a biomechanical process. To improve patients' function and possibly reduce disease progression, a biomechanical approach should be included in the treatment plan for patients with knee osteoarthritis. Foot orthoses and knee braces have been shown in selected patients to have a role in the management of unicompartmental knee osteoarthritis.

Rabbit knee joint biomechanics: motion analysis and modeling of forces during hopping

Although the rabbit hindlimb has been commonly used as an experimental animal model for studies of osteoarthritis, bone growth and fracture healing, the in vivo biomechanics of the rabbit knee joint have not been quantified. The purpose of this study was to investigate the kinematic and kinetic patterns during hopping of the adult rabbit, and to develop a model to estimate the joint contact force distribution between the tibial plateaus. Force platform data and three-dimensional motion analysis using infrared markers mounted on intracortical bone pins were combined to calculate the knee and ankle joint intersegmental forces and moments. A statically determinate model was developed to predict muscle, ligament and tibiofemoral joint contact forces during the stance phase of hopping. Variations in hindlimb kinematics permitted the identification of two landing patterns, that could be distinguished by variations in the magnitude of the external knee abduction moment. During hopping, the prevalence of an external abduction moment led to the prediction of higher joint contact forces passing through the lateral compartment as compared to the medial compartment of the knee joint. These results represent critical data on the in vivo biomechanics of the rabbit knee joint, which allow for comparisons to both other experimental animal models and the human knee, and may provide further insight into the relationships between mechanical loading, osteoarthritis, bone growth, and fracture healing.

Hauteur radiologique de l’interligne fémoro-tibial médial avant et immédiatement après méniscectomie

PURPOSE OF THE STUDY

The purpose of this prospective study was to develop and evaluate a method for measuring the femorotibial joint space and to assess the effect of meniscectomy.

MATERIAL AND METHODS

This study was conducted in a consecutive series of 36 patients undergoing arthroscopic meniscectomy for lesions of the medial meniscus on a stable knee. The height of the joint space was measured on x-rays taken in the morning before the operation then ten days later. X-rays were obtained for both knees in complete extension and in the 30 degrees flexion position. The height of the joint space was measured on the digital version of the x-rays midway between the vertical tangents of the posterior limits of the medial condyle.

RESULTS

Readings were not reader dependent and demonstrated no significant difference between the pre and postmeniscectomy height of the medial femorotibial space (30 degrees flexion view, 5.2 +/- 1 and 5.2 +/- 1 before meniscectomy for reader 1 and 5.2 +/- 1 and 5.2 +/- 1 for reader 2 (p=0.05 for Student-Fisher test for paired values). The heights measured by the two readers were correlated (correlation coefficient test).

DISCUSSION

The height of the medial femorotibial joint space can be measured reproductibly on plain x-rays of the knee in the standard flexion position. We were unable to demonstrate any significant difference in joint space between measures taken before and after meniscectomy.

Expression of the CD44 variant isoform 5 in the human osteoarthritic knee joint: correlation with radiological, histomorphological, and biochemical parameters

PURPOSE

The purpose of this study was to correlate expression of CD44v5 in osteoarthritic synovium, cartilage, and synovial fluid with radiographical, histomorphological, and biochemical data.

METHODS

Cartilage and synovia specimens of 27 patients with osteoarthritis were histomorphologically assessed according to Mankin and Pelletier, respectively. Extended weight-bearing antero-posterior radiographs were evaluated according to Kellgren and Ahlback. Expression of membrane-bound CD44v5 was analyzed by immunohistochemistry and levels of soluble CD44v5 were determined by ELISA.

RESULTS

Expression of CD44v5 in cartilage and synovia was detected in 67% and 59% of the patients, respectively. Immunohistochemical findings in cartilage correlated significantly with structural cartilage changes (p < 0.001), whereas no correlation was found between expression in synovia and inflammatory synovial changes. Additionally, no relationship was evident between CD44v5 expression and radiographical data, but expression in cartilage and synovium was significantly correlated with each other (p < 0.04). Surprisingly, expression of CD44v5 in both cartilage and synovia was negatively correlated with synovial fluid levels of TNFalpha (p < 0.03 and p < 0.02, respectively), and no association was evident with levels of IL-1beta.

CONCLUSIONS

The data demonstrate expression of CD44v5 in osteoarthritic cartilage and synovia, probably independent of joint inflammation. But more importantly, expression of this receptor variant in cartilage seems to be strongly related to the degree of cartilage destruction.

Effects of removal of the acetabular labrum in a sheep hip model

OBJECTIVE

The aim of this study was to learn whether partial resection of the acetabular labrum would lead to degenerative arthritis in an ovine model.

METHODS

A 2 cm segment of labrum was removed from one hip in 18 mature Swiss Alpine sheep and a sham procedure was performed on the opposite side. Animals were permitted ad lib activity until sacrifice at 6, 12 or 24 weeks. The hip joint was removed en bloc, and loaded with a force of one body weight, using a custom device designed to recreate a physiologic joint reaction force. While under load, the joint was plunge frozen, and then fixed by freeze substitution using aldehydes in methanol/acetone solvents. The entire joint was embedded in methacrylate and sectioned in a standardized frontal plane following the reaction force and including the femoral neck and the acetabular fossa. The sections were evaluated for concentricity and evidence of arthrosis. Six hip joints of three sheep with no surgical procedure were loaded with high or low loads and served as non-surgical controls.

RESULTS

Degenerative changes were present in all surgical hips, but the changes were symmetrical and mild. In 16 of 18 hips, the labrum regenerated to the extent that dense fibrous scar extending from the surgically denuded origin filled the defect.

CONCLUSION

Resection of the labrum does not cause rapid degeneration or altered stability of the sheep hip.

Whole-Organ Magnetic Resonance Imaging Score (WORMS) of the knee in osteoarthritis

OBJECTIVES

To describe a semi-quantitative scoring method for multi-feature, whole-organ evaluation of the knee in osteoarthritis (OA) based on magnetic resonance imaging (MRI) findings. To determine the inter-observer agreement of this scoring method. To examine associations among the features included in the scoring method.

METHODS

Nineteen knees of 19 patients with knee OA were imaged with MRI using conventional pulse sequences and a clinical 1.5 T MRI system. Images were independently analyzed by two musculoskeletal radiologists using a whole-organ MRI scoring method (WORMS) that incorporated 14 features: articular cartilage integrity, subarticular bone marrow abnormality, subarticular cysts, subarticular bone attrition, marginal osteophytes, medial and lateral meniscal integrity, anterior and posterior cruciate ligament integrity, medial and lateral collateral ligament integrity, synovitis/effusion, intraarticular loose bodies, and periarticular cysts/bursitis. Intraclass correlation coefficients (ICC) were determined for each feature as a measure of inter-observer agreement. Associations among the scores for different features were expressed as Spearman Rho.

RESULTS

All knees showed structural abnormalities with MRI. Cartilage loss and osteophytes were the most prevalent features (98% and 92%, respectively). One of the least common features was ligament abnormality (8%). Inter-observer agreement for WORMS scores was high (most ICC values were >0.80). The individual features showed strong inter-associations.

CONCLUSION

The WORMS method described in this report provides multi-feature, whole-organ assessment of the knee in OA using conventional MR images, and shows high inter-observer agreement among trained readers. This method may be useful in epidemiological studies and clinical trials of OA.

Imaging of the disease process

Until recently, imaging evaluation of osteoarthritis (OA) has relied primarily on conventional radiography. Using radiography in clinical practice or clinical research, however, has been fraught with difficulty. Techniques for reproducibly acquiring serial radiographs of joints have improved considerably over the past several years. However, the greatest promise for advancing knowledge about OA and its treatment lies in magnetic resonance imaging (MRI) and its unique ability to examine the joint as a whole organ. In contrast to conventional radiography, MRI can directly visualize the articular cartilage, synovium, menisci, and other intra-articular structures important to the functional integrity of joints. There have been considerable advances in MRI of articular cartilage in particular over the past several years. However, much of this has come from small cross-sectional studies, and published longitudinal studies remain quite scant. The following discussion reviews the current status of imaging in OA and points to where changes might be anticipated in the future.

Articular cartilage repair: basic science and clinical progress. A review of the current status and prospects

OBJECTIVE

To review the basic scientific status of repair in articular cartilage tissue and to assess the efficiency of current clinical therapies instigated for the treatment of structural lesions generated therein as a result of trauma or during the course of various diseases, notably osteoarthritis (OA). Current scientific trends and possible directions for the future will also be discussed.

DESIGN

A systematic and critical analysis is undertaken, beginning with a description of the spontaneous repair responses in different types of lesion. Surgical interventions aimed at inducing repair without the use of active biologics will then be considered, followed by those involving active biologics and those drawing on autogenic and allogeneic tissue transplantation principles. Cell transplantation approaches, in particular novel tissue engineering concepts, will be critically presented. These will include growth-factor-based biological treatments and gene transfection protocols. A number of technical problems associated with repair interventions, such as tissue integration, tissue retention and the role of mechanical factors, will also be analysed.

RESULTS

A critical analysis of the literature reveals the existence of many novel and very promising biologically-based approaches for the induction of articular cartilage repair, the vast majority of which are still at an experimental phase of development. But prospective, double-blinded clinical trials comparing currently practiced surgical treatments have, unfortunately, not been undertaken.

CONCLUSION

The existence of many new and encouraging biological approaches to cartilage repair justifies the future investment of time and money in this research area, particularly given the extremely high socio-economic importance of such therapeutic strategies in the prevention and treatment of these common joint diseases and traumas. Clinical epidemiological and prospective trials are, moreover, urgently needed for an objective, scientific appraisal of current therapies and future novel approaches.