Desmoplastic Fibroblastoma of the Ankle: A Case Report of a Rare Localization and a Literature Review.

Introduction: Desmoplastic fibroblastoma is a rare, slow-growing benign soft tissue tumor. It has a wide anatomical distribution and mainly affects adult males. Fourteen percent of cases occur in the ankle or foot. Case Report: In this study, we report a rare location of desmoplastic fibroblastoma on the ankle of a 76-year-old female, discovered as a slowly growing mass. Discussion: Desmoplastic fibroblastoma is an anatomical and clinical entity. It appears macroscopically as a pseudocartilaginous structure and histologically as a stellate or spindle-shaped fibroblastic proliferation in a collagenous stroma. Conclusion: Desmoplastic fibroblastoma has anatomical specificities and should still be clearly distinguished from certain malignant tumors.

Increasing Collagen to Bioink Drives Mesenchymal Stromal Cells-Chondrogenesis from Hyaline to Calcified Layers.

The bioextrusion of mesenchymal stromal cells (MSCs) directly seeded in a bioink enables the production of three-dimensional (3D) constructs, promoting their chondrogenic differentiation. Our study aimed to evaluate the effect of different type I collagen concentrations in the bioink on MSCs' chondrogenic differentiation. We printed 3D constructs using an alginate, gelatin, and fibrinogen-based bioink cellularized with MSCs, with four different quantities of type I collagen addition (0.0, 0.5, 1.0, and 5.0 mg per bioink syringe). We assessed the influence of the bioprinting process, the bioink composition, and the growth factor (TGF-ꞵ1) on the MSCs' survival rate. We confirmed the biocompatibility of the process and the bioinks' cytocompatibility. We evaluated the chondrogenic effects of TGF-ꞵ1 and collagen addition on the MSCs' chondrogenic properties through macroscopic observation, shrinking ratio, reverse transcription polymerase chain reaction, glycosaminoglycan synthesis, histology, and type II collagen immunohistochemistry. The bioink containing 0.5 mg of collagen produces the richest hyaline-like extracellular matrix, presenting itself as a promising tool to recreate the superficial layer of hyaline cartilage. The bioink containing 5.0 mg of collagen enhances the synthesis of a calcified matrix, making it a good candidate for mimicking the calcified cartilaginous layer. Type I collagen thus allows the dose-dependent design of specific hyaline cartilage layers.

CORIN KneeTec DeepDishTM: Functional outcomes after a follow-up of 12 months and comparison with the STRYKER Triathlon PS.

Several competing concepts of anteroposterior stabilization have been developed for total knee arthroplasty (TKA), with an overall great success despite some differences in terms of clinical or radiological outcomes. The CORIN KneeTec DeepDish TM is a novel mobile-bearing implant, stabilized with an ultra-congruent deep-dish poly- ethylene insert. The aim of the present study was to report clinical and radiological outcomes of a series of patients who received the KneeTec DeepDish TM after a follow-up of 12 months, and to compare them to those of a comparable series of patients who received the STRYKER Triathlon ® posterior- stabilized. This was a retrospective comparative cohort study (level of evidence III). Demographic data, radiographic data and range of motion (ROM), as well the International Knee Society score and Oxford Knee Score were collected pre-operatively, and after a follow-up of 12 months. 106 KneeTec DeepDish TM and 80 Triathlon ® PS were evaluated at follow-up. Patients who received the KneeTec DeepDish TM had significant improvement in ROM, radiographic and clinical outcomes. There were no significant differences between the cohorts in terms of ROM, radiographic and clinical outcomes, as well as antero-posterior stability. This study is the first to report the 12-month outcomes of the CORIN KneeTec DeepDish TM. The novel KneeTec DeepDish TM achieved comparable ROM, radiographic and clinical outcomes to the Triathlon ® PS after 12 months. Further studies will be necessary to evaluate the mid- to long-term outcomes of the KneeTec DeepDish TM .

Open-Label Pilot Study of a Single Intra-Articular Injection of Mannitol-Modified Cross-Linked Hyaluronic Acid (HANOX-M-XL) for the Treatment of the First Metatarsophalangeal Osteoarthritis (Hallux Rigidus): The REPAR Trial.

Purpose: The purpose of this study was to obtain information on safety and short-term efficiency of a single intra-articular injection of mannitol-modified cross-linked hyaluronic acid (HANOX-M-XL) in patients with painful first metatarsophalangeal joint osteoarthritis (1stMTPJ-OA). Methods: The study involved an observational, single-arm, prospective multicentre trial, with a 3-month follow-up. Inclusion criteria were patients with symptomatic 1st MTPJ-OA not relieved by analgesics and / or non-steroidal-anti-inflammatory drugs and / or foot orthotic. All patients received a single, imaging-guided intra-articular (IA) injection of 1 mL of HANOX-M-XL in the 1st MTPJ. The primary outcome was the change in pain between the date of injection and month 3. The secondary outcomes were the patient assessment of effectiveness, the decrease in painkiller use and the influence of the radiographic score on the clinical efficacy. Results: Sixty-five participants (72.3% women, mean age = 60) were included in the trial. Coughlin-Shurnas radiological grade was 1 in 28 patients, 2 in 29, and 3 in 6. At baseline and month 3, the average pain (0-10) was 6.5 ± 1.8 and 2.8 ± 2.3, respectively. The change in pain score was highly significant (-3.1 ± 2.9; P < .0001). At baseline there was no statistically difference in pain between the radiological stages (P = .69). At endpoint, the average pain score was 2.0 ± 1.9 in x-ray stage 1, 3.1 ± 2.3 in stage 2 and 3.3 ± 2.4 in stage 3 (P = .001). Mild to moderate adverse reactions were reported by 15 patients. All were a transient increase of the hallux pain that occurred immediately and up to 6 hours after injection and resolved in 1 to 7 days. Conclusion: This pilot study suggests that a single IA injection of HANOX-M-XL is safe and mainly benefits patients with mild moderate 1st MTPJ-OA. Further randomized controlled trials are necessary to confirm these preliminary encouraging results.

Brachymetatarsia: Surgical Management, Case Report, and Literature Review.

Background: Brachymetatarsia is defined by an abnormal shortening of the metatarsal bone. This rare condition is mostly primary and congenital. Consequences of this malformation are both esthetic and functional, due to pain and mechanical problems in the forefoot. Surgical management is an important part of patient care. There are two main options: gradual lengthening by progressive callotosis distraction using an external fixator and one stage lengthening using bone graft and osteotomy of the bone. This review presents two cases using the one stage lengthening surgical management method. We also discuss some reports in the literature with the aim to compare the advantages and disadvantages of the two surgical methods. Literature concerning the surgical management of brachymetatarsia was identified using the PubMed and Google Scholar databases. Patient Presentation. We describe two female patients aged 20 and 26 years who underwent one stage lengthening surgery of the fourth toe with isolated brachymetatarsia using an iliac bone graft and internal fixator plate. The two patients had a lengthening of around 10 mm after postoperative evaluation. No skin complications were noted, but one of the patients reported flexor stiffness after surgery. Concerning the functional and cosmetic aspects, the two patients are satisfied with the management. Conclusions: In the literature, one stage lengthening seems to be the most favorable option for the care of brachymetatarsia. Studies show a short healing time and fewer complications like infection, stiffness, malalignment, and malunion. Some reviews note the utility of the gradual lengthening of severe brachymetatarsia when a longer lengthening is necessary. There is no definite consensus concerning the management of brachymetatarsia.

Respective stemness and chondrogenic potential of mesenchymal stem cells isolated from human bone marrow, synovial membrane, and synovial fluid.

BACKGROUND: MSCs isolated from bone marrow (BM-MSCs) have well-established chondrogenic potential, but MSCs derived from the synovial membrane (SM-MSCs) and synovial fluid (SF-MSCs) are thought to possess superior chondrogenicity. This study aimed to compare the in vitro immunophenotype and trilineage and chondrogenic potential of BM-MSCs to SM-MSCs and SF-MSCs. METHODS: MSCs were isolated from bone marrow (BM-MSCs), synovial membrane (SM-MSCs), and synovial fluid (SF-MSCs) extracted from the hips (BM) and knees (SM and SF) of advanced OA patients undergoing arthroplasty. Flow cytometric analysis was used at P2 to evaluate cell stemness. The trilinear differentiation test was performed at P2. At P3, MSC-seeded collagen sponges were cultured in chondrogenic medium for 28 days. Chondrogenic gene expression was quantified by qRT-PCR. Finally, the implants were stained to assess the deposition of proteoglycans and type II collagen. RESULTS: Despite variability, the immunophenotyping of BM-MSCs, SM-MSCs, and SF-MSCs was quite similar. All cell types were positive for the expression of stem cell markers and negative for exclusion markers. Additionally, chondrogenic differentiation and hypertrophy were more pronounced in BM-MSCs (ACAN, SOX9, COL2B, and COL10A) than in SF-MSCs, with SM-MSCs having intermediate characteristics. Concerning matrix synthesis, the three cell types were equipotent in terms of GAG content, while BM-MSC ECM synthesis of type II collagen was superior. CONCLUSIONS: Chondrogenic MSCs are easily collected from SM and SF in advanced human OA, but in vitro chondrogenesis that is superior to age-matched BM-MSCs should not be expected. However, due to intra-articular priming, SF-MSCs did not overexpress hypertrophic gene.

Surgical options for hallux rigidus: state of the art and review of the literature.

Hallux rigidus is a painful condition of the great toe characterized by restriction of the metatarsophalangeal range of motion and progressive osteophyte formation. Many etiologies have been postulated including excessive length of the first ray, trauma, abnormally elevated first metatarsal and a positive family history. However, most cases are likely idiopathic. Plain radiographs are used to grade the severity of hallux rigidus. The more comprehensive grading is represented by Coughlin and Shurnas' system that introduced a four-grade classification. When nonoperative treatment fails to provide relief, surgery should be performed. The goal of surgery is to relieve pain, maintain stability of the first metatarsophalangeal joint and improve function and quality of life. Operative treatments can be divided into joint sparing (e.g., cheilectomy with or without associated osteotomies) versus joint sacrificing (e.g., arthroplasty or arthrodesis). There are a variety of osteotomies available for treatment of hallux rigidus (phalanx and/or metatarsal osteotomies). Newer techniques of interpositional arthroplasty as well as new hemi-arthroplasty designs, including synthetic cartilage implants, offer promising options for preservation of motion. The choice of procedure is based on the condition of the joint, patient's goals and expectations of the surgical outcome, and patient's motivation. This article discusses various procedures along with clinical outcomes and complications. The advantages and disadvantages of each procedure are discussed.

In vitro and in vivo potentialities for cartilage repair from human advanced knee osteoarthritis synovial fluid-derived mesenchymal stem cells.

BACKGROUND: Mesenchymal stem cells (MSCs) are found in synovial fluid (SF) and can easily be harvested during arthrocentesis or arthroscopy. However, SF-MSC characterization and chondrogenicity in collagen sponges have been poorly documented as well as their hypothetical in vivo chondroprotective properties with intra-articular injections during experimental osteoarthritis (OA). METHODS: SF-MSCs were isolated from human SF aspirates in patients suffering from advanced OA undergoing total knee joint replacements. SF-MSCs at passage 2 (P2) were characterized by flow cytometry for epitope profiling. SF-MSCs at P2 were subsequently cultured in vitro to assess their multilineage potentials. To assess their chondrogenicity, SF-MSCs at P4 were seeded in collagen sponges for 4 weeks under various oxygen tensions and growth factors combinations to estimate their gene profile and matrix production. Also, SF-MSCs were injected into the joints in a nude rat anterior cruciate ligament transection (ACLT) to macroscopically and histologically assess their possible chondroprotective properties,. RESULTS: We characterized the stemness (CD73+, CD90+, CD105+, CD34-, CD45-) and demonstrated the multilineage potency of SF-MSCs in vitro. Furthermore, the chondrogenic induction (TGF-ß1 ± BMP-2) of these SF-MSCs in collagen sponges demonstrated a good capacity of chondrogenic gene induction and extracellular matrix synthesis. Surprisingly, hypoxia did not enhance matrix synthesis, although it boosted chondrogenic gene expression (ACAN, SOX9, COL2A1). Besides, intra-articular injections of xenogenic SF-MSCs did exert neither chondroprotection nor inflammation in ACLT-induced OA in the rat knee. CONCLUSIONS: Advanced OA SF-MSCs seem better candidates for cell-based constructs conceived for cartilage defects rather than intra-articular injections for diffuse OA.

History of surgical treatments for hallux valgus.

In the nineteenth century, the prevalent understanding of the hallux valgus was that it was purely an enlargement of the soft tissue, first metatarsal head, or both, most commonly caused by ill-fitting footwear. Thus, treatment had varying results, with controversy over whether to remove the overlying bursa alone or in combination with an exostectomy of the medial head. Since 1871, when the surgical technique was first described, many surgical treatments for the correction of hallux valgus have been proposed. A number of these techniques have come into fashion, and others have fallen into oblivion. Progress in biomechanical knowledge, and improvements in materials and supports have allowed new techniques to be developed over the years. We have developed techniques that sacrifice the metatarsophalangeal joint (arthrodesis, arthroplasties), as well as conservative procedures, and one can distinguish those which only involve the soft tissues from those that are linked with a first ray osteotomy.

Nacre, a natural, multi-use, and timely biomaterial for bone graft substitution.

During the past two decades, with a huge and rapidly increasing clinical need for bone regeneration and repair, bone substitutes are more and more seen as a potential solution. Major innovation efforts are being made to develop such substitutes, some having advanced even to clinical practice. It is now time to turn to natural biomaterials. Nacre, or mother-of-pearl, is an organic matrix-calcium carbonate coupled shell structure produced by molluscs. In vivo and in vitro studies have revealed that nacre is osteoinductive, osteoconductive, biocompatible, and biodegradable. With many other outstanding qualities, nacre represents a natural and multi-use biomaterial as a bone graft substitute. This review aims at summarising the current needs in orthopaedic clinics and the challenges for the development of bone substitutes; most of all, we systematically review the physiological characteristics and biological evidence of nacre's effects centred on osteogenesis, and finally we put forward the potential use of nacre as a bone graft substitute. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 662-671, 2017.

Percutaneous autologous bone marrow injection for treatment of delayed and non-union of long bone: a retrospective study of 45 cases.

BACKGROUND: Non-union of long bones is still a current problem in traumatology. Although corticocancellous bone autograft remains the usual procedure for the treatment of non-union, innovative therapies such as, percutaneous autologous concentrated bone marrow grafting (PABMG), are now appearing. MATERIAL AND METHODS: Over a period of 8 years, 45 non-union of long bones were treated by PABMG in the Department of Orthopaedic and Traumatologic Surgery (University Hospital of Nancy, France): 26 tibiae, 16 femurs, 3 humeri. Efficiency was evaluated by clinical criteria: full weight-bearing without pain, absence of motion at non-union site, and radiological criteria: healing of 3 corticales out of 4. RESULTS: Eighteen out of 28 non-unions at the tibia were healed (69%), 10 at the femur (63%), but none was noticed at the humerus. Some pejorative prognosis factors were noted such as: tobacco, alcohol abuse, diabetes and history of infection at the fracture site. An earlier grafting improved the success rate. The number of CFU-F (Colony Forming Unit Fibroblastic) affected the healing time more than the healing rate. CONCLUSION: The procedure, even though a little invasive, enables the healing of non-union in two out of three cases with less morbidity than conventional procedures. This procedure fits perfectly into the therapeutic arsenal of non-union.

Antegrade nailing evolution for proximal humeral fractures, the Telegraph IV(®): a study of 67 patients.

INTRODUCTION: There are multiple surgical treatment methods for proximal humerus fractures (PHF), but rarely do they provide satisfactory results. The objective of this study was to assess radioclinical outcomes and complications in patients treated using a modern intramedullary nailing system the Telegraph I(®). MATERIALS AND METHODS: This is an observational multicenter study cohort conducted between March 2008 and December 2009 on 105 patients admitted with a diagnosis of PHF and operated on two trauma I centers. The Neer and Articular Surgical neck Tuberosities classifications were used for the study. The primary outcome measure was the clinical Constant score. Follow-up of the patients was done at 6 weeks, 3 months, 6 months, 1 year, and 3 years after the procedure. RESULTS: A total of 67 patients (51 women and 16 men) were assessed at a mean of 38 months. The weighted Constant score was 88%. The mean rate of complications was 16%. The weighted Constant scores were 84 and 95% for the 2- and 3-part groups, respectively. Articular 4-part fractures had an average score of 86% when they were valgus impacted and 67% for complex disengaged fractures. Notably, the complication rate was 67% for this latter group. CONCLUSIONS: Our clinical results support the use of this antegrade nailing for extra-articular and valgus-impacted articular fractures. This procedure does not appear suitable for displaced articular fracture for which arthroplasty may be indicated by elderly.

Influencing factors of functional result and bone union in tibiotalocalcaneal arthrodesis with intramedullary locking nail: a retrospective series of 30 cases.

BACKGROUND: Initially considered as an established salvage procedure for tibiotalocalcaneal arthrodesis (TTCA), intramedullary nailing indications have expanded as evidenced in recent literature. We have tried to identify factors influencing functional result and bone union. METHODS: In a retrospective study, 30 patients were treated by a TTCA between January 2006 and November 2011. Indications, operative technique, bone fusion, X-rays and functional result [American Foot and Ankle Society (AOFAS) and short-form health survey (SF-36) scores] before and after surgery were registered and analyzed. RESULTS: Thirty cases of TTCA were included. The patient's average age was 52 (range 24-90). Union rate was 86% for the tibiotalar joint and 74% for the subtalar joint with an average follow-up of 25.4 months (8-67). The mean AOFAS' score significantly improved (from 37 to 59) as the SF-36' score. Global complication rate was about 56%. It has not been possible to identify factors significantly influencing bone fusion or functional results. All septic cases achieved fusion without any septic resurgence. CONCLUSION: Retrograde intramedullary nailing in TTCA is an effective technique, which allows good clinical results even in case of septic history of the patient. Fusion rate and functional results were not significantly influenced by any of the factors examined in this study.

Osteogenic differentiation of human bone marrow mesenchymal stem cells in hydrogel containing nacre powder.

Nacre (or mother of pearl) can facilitate bone cell differentiation and can speed up their mineralization. Here we report on the capability of nacre to induce differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs) and the production of extracellular matrix. hBM-MSCs were encapsulated in an alginate hydrogel containing different concentrations of powdered nacre and cultured in the same environment until Day 28. Analysis of osteogenic gene expression, histochemistry, second harmonic generation (SHG) microscopy, and Raman scattering spectroscopy were used to characterize the synthesis of the extracellular matrix. In the presence of nacre powder, a significant increase in matrix synthesis from D21 in comparison with pure alginate was observed. Histochemistry revealed the formation of a new tissue composed of collagen fibers in the presence of nacre (immunostaining and SHG), and hydroxyapatite crystals (Raman) in the alginate beads. These results suggest that nacre is efficient in hBM-MSCs differentiation, extracellular matrix production and mineralization in alginate 3D biomaterials.

Effect of dynamic loading on MSCs chondrogenic differentiation in 3-D alginate culture.

Mesenchymal stem cells (MSCs) are regarded as a potential autologous source for cartilage repair, because they can differentiate into chondrocytes by transforming growth factor-beta (TGF-ß) treatment under the 3-dimensional (3-D) culture condition. In addition to these molecular and biochemical methods, the mechanical regulation of differentiation and matrix formation by MSCs is only starting to be considered. Recently, mechanical loading has been shown to induce chondrogenesis of MSCs in vitro. In this study, we investigated the effects of a calibrated agitation on the chondrogenesis of human bone MSCs (MSCs) in a 3-D alginate culture (day 28) and on the maintenance of chondrogenic phenotypes. Biomechanical stimulation of MSCs increased: (i) types 1 and 2 collagen formation; (ii) the expression of chondrogenic markers such as COMP and SOX9; and (iii) the capacity to maintain the chondrogenic phenotypes. Notably, these effects were shown without TGF-ß treatment. These results suggest that a mechanical stimulation could be an efficient method to induce chondrogenic differentiation of MSCs in vitro for cartilage tissue engineering in a 3-D environment. Additionally, it appears that MSCs and chondrocyte responses to mechanical stimulation are not identical.

Ambivalent properties of hyaluronate and hylan during post-traumatic OA in the rat knee.

AIM: To determine whether viscosupplementation with intra-articular (i.a.) low- or high-molecular-weight hyaluronate (HA) injections influenced both chondral and synovial lesions in rats with surgically-induced OA knee. METHODS: On D0, rats underwent anterior cruciate ligament transection (ACLX) and were divided in 4 groups: sham group, ACLX-saline control group, ACLX-hyaluronate group, ACLX-hylan group. IA injections were performed on D7, D14 and D21. Histological grading of chondral and synovial lesions were performed on D28. Concomitant immunostainings of Caspase3a and Hsp70 were also performed. RESULTS: Articular damages were significantly reduced in both HAs-treated knee joints. In contrast, a significant increase of histological score of synovial inflammation was noted in both ACLX + HAs groups. Apoptotic events significantly decreased as anti-apoptotic Hsp70 expression increased significantly in both HAs groups. CONCLUSION: HAs may exert, independently of its molecular weight, ambivalent properties on articular structures, simultaneously exerting chondroprotective properties and promoting long-term subacute synovitis.

Metastatic renal cell carcinoma presenting as foot metastasis: case report and review of the literature.

Malignant tumors frequently metastasize to bone centrally in the skeleton. Metastatic disease distal to the knee is unusual. Metastasis to the foot (acrometastasis) is rare (0.01%) and is usually a late manifestation of disseminated disease. The purpose of this article is to present a rare case of metastatic renal cell carcinoma with foot metastasis as the primary manifestation along with another rare localization of metastatic disease distal to the knee, in the contralateral tibial diaphysis. To highlight the delay in diagnosis of such a rare condition to consider it in the diagnosis of a painful foot, we also present a review of the literature.

Expression of chondrogenic genes by undifferentiated vs. differentiated human mesenchymal stem cells using array technology.

This study investigated the gene expression profile of human mesenchymal stem cells seeded in collagen sponge for 28 days in three different mediums: (1) basal medium as control containing ITS alone, (2) ITS+TGF-ß1 alone or (3) ITS 1% supplemented sequentially by TGF-ß1 (D3-D14) followed by BMP-2 (D15-D28). Differential expression of 84 genes implicated in chondrogenic and osteogenic differentiation of MSCs was analyzed at D28 by real-time RT-PCR array technology. TGF-ß1 alone down-regulated two genes, CD36 and cathepsin K. Sixteen genes were significantly up-regulated, notably type 2 and type 10 collagens, COMP and Sox9. The sequential combination of TGF-ß1 and BMP-2 produced a similar profile with prominent expression of type 2 collagen and the alkaline phosphatase gene. Interestingly, in this in vitro condition, RUNX2 was not up-regulated, suggesting that the sequential combination of TGF-ß1/BMP2 enhances the hypertrophic chondrogenic profile without turning towards the osteoblastic pathway.

New trends in MRI of cartilage: Advances and limitations in small animal studies.

Due to the actual interest for bioengineering in the osteoarthritis (OA) healing context, researchers need accurate qualitative and quantitative methodologies to evaluate in vivo the integration and functionality of their cartilage-like biomaterials. As in clinical diagnostic strategies, advances in Magnetic Resonance Imaging (MRI) seem promising for non-vulnerant assessments of articular cartilage bio-architecture and morphology in small animal models. These experimental models are commonly used to monitor the physiopathology of OA and to evaluate therapeutic responses mediated by chondroprotective drugs or tissue engineering. Nowadays, the application of MR protocols to in vivo small animal cartilage imaging is achievable with the development of high magnetic fields and the adaptation of methodologies to reach the required spatial resolution and contrast. The purpose of this article is to summarize these current MRI strategies used for in vivo small animal articular cartilage assessments.

In vivo high-resolution MRI (7T) of femoro-tibial cartilage changes in the rat anterior cruciate ligament transection model of osteoarthritis: a cross-sectional study.

OBJECTIVE: To assess OA-related changes in mean compartmental femorotibial cartilage thickness in rat knees by three-dimensional (3D) MRI (7T). METHODS: MRI was performed in vivo at 7T on OA and untouched contralateral knee joints. Gradient Echo Fast Imaging 3D MR images were acquired sequentially in surgically induced OA (D0) in 40 Wistar rats (anterior cruciate ligament transection). Mean femoral (trochlear, lateral and medial) and tibial (lateral and medial) cartilage thicknesses were quantified from a 2D MRI slide in weight-bearing areas and from a 3D MRI data set. At each time-point [Day (D)8, D14, D21, D40 and D60], eight animals (16 knees) were sacrificed for concomitant histomorphometry. RESULTS: As body weight dramatically increased throughout the experiment (+150%, baseline vs endpoint), all compartmental mean cartilage thicknesses noticeably decreased (D8, D14) and then remained relatively stable. Femoral compartments in OA knees were thinner at the end of the experiment than in contralateral age-matched knees. Conversely, lateral and medial tibial cartilages were thicker than controls. Histological correlation was significant only in untouched healthy cartilages (3D better than 2D). CONCLUSIONS: 3D MRI (7T) enables in vivo monitoring of compartmental changes in OA-related femorotibial rat cartilage thickness vs contralateral age-matched knees.