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Fetal cartilage fully regenerates following injury, while in adult mammals cartilage injury leads to osteoarthritis (OA). Thus, in this study, we compared the in vivo injury response of fetal and adult ovine articular cartilage histologically and proteomically to identify key factors of fetal regeneration. In addition, we compared the secretome of fetal ovine mesenchymal stem cells (MSCs) in vitro with injured fetal cartilage to identify potential MSC-derived therapeutic factors. Cartilage injury caused massive cellular changes in the synovial membrane, with macrophages dominating the fetal, and neutrophils the adult, synovial cellular infiltrate. Correspondingly, proteomics revealed differential regulation of pro- and anti-inflammatory mediators and growth-factors between adult and fetal joints. Neutrophil-related proteins and acute phase proteins were the two major upregulated protein groups in adult compared to fetal cartilage following injury. In contrast, several immunomodulating proteins and growth factors were expressed significantly higher in the fetus than the adult. Comparison of the in vitro MSCs proteome with the in vivo fetal regenerative signature revealed shared upregulation of 17 proteins, suggesting their therapeutic potential. Biomimicry of the fetal paracrine signature to reprogram macrophages and modulate inflammation could be an important future research direction for developing novel therapeutics.

Synovial joints are complex structures that enable normal locomotion. Following injury, they undergo a series of changes, including a prevalent inflammatory response. This increases the risk for development of osteoarthritis (OA), the most common joint disorder. In healthy joints, macrophages are the predominant immune cells. They regulate bone turnover, constantly scavenge debris from the joint cavity and, together with synovial fibroblasts, form a protective barrier. Macrophages thus work in concert with the non-hematopoietic stroma. In turn, the stroma provides a scaffold as well as molecular signals for macrophage survival and functional imprinting: "a macrophage niche". These intricate cellular interactions are susceptible to perturbations like those induced by joint injury. With this review, we explore how the concepts of local tissue niches apply to synovial joints. We introduce the joint micro-anatomy and cellular players, and discuss their potential interactions in healthy joints, with an emphasis on molecular cues underlying their crosstalk and relevance to joint functionality. We then consider how these interactions are perturbed by joint injury and how they may contribute to OA pathogenesis. We conclude by discussing how understanding these changes might help identify novel therapeutic avenues with the potential of restoring joint function and reducing post-traumatic OA risk., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Haubruck, Pinto, Moradi, Little and Gentek.)

Cartilage defects in temporomandibular disorders (TMD) lead to chronic pain and seldom heal. Synovium-derived mesenchymal stem cells (SMSCs) exhibit superior chondrogenesis and have become promising seed cells for cartilage tissue engineering. However, local inflammatory conditions that affect the repair of articular cartilage by SMSCs present a challenge, and the specific mechanism through which the function remains unclear. Thus, it is important to explore the chondrogenesis of SMSCs under inflammatory conditions of TMD such that they can be used more effectively in clinical treatment. In this study, we obtained SMSCs from TMD patients with severe cartilage injuries. In response to stimulation with IL-1 β , which is well known as one of the most prevalent cytokines in TMD, MMP13 expression increased, while that of SOX9, aggrecan, and collagen II decreased during chondrogenic differentiation. At the same time, IL-1 β upregulated the expression of mTOR and decreased the ratio of LC3-II/LC3-I and the formation of autophagosomes. Further study revealed that rapamycin pretreatment promoted the migration of SMSCs and the expression of chondrogenesis-related markers in the presence of IL-1 β by inducing autophagy. 3-Benzyl-5-((2-nitrophenoxy)methyl)-dihydrofuran-2(3H)-one (3BDO), a new activator of mTOR, inhibited autophagy and increased the expression of p-GSK3 β ser9 and β -catenin, simulating the effect of IL-1 β stimulation. Furthermore, rapamycin reduced the expression of mTOR, whereas the promotion of LC3-II/LC3-I was blocked by the GSK3 β inhibitor TWS119. Taken together, these results indicate that rapamycin enhances the chondrogenesis of SMSCs by inducing autophagy, and GSK3 β may be an important regulator in the process of rapamycin-induced autophagy. Thus, inducing autophagy may be a useful approach in the chondrogenic differentiation of SMSCs in the inflammatory microenvironment and may represent a novel TMD treatment., Competing Interests: The authors declare no conflicts of interest in relation to this paper., (Copyright © 2020 Wenjing Liu et al.)

Background: The diagnostic value of positive contrast radiography in the work-up of suspected synovial infection in horses with limb wounds near synovial structures has yet to be systematically evaluated., Objectives: To determine the specificity, sensitivity and positive and negative predictive values of positive contrast radiography for identification of synovial infection in a population of horses with limb wounds., Study Design: Retrospective case study comparing the performance of positive contrast radiography to the gold standard of synovial fluid cytology in horses presenting with limb wounds in the vicinity of synovial structures., Methods: Case records of horses presenting to the Royal Veterinary College Equine Hospital between 2010 and 2015 with limb wounds that may have compromised adjacent synovial structures were analysed. Synovial fluid cytology results were used to categorise synovial structures in infected and noninfected groups. Positive contrast radiography results were compared between infected and noninfected groups and sensitivity, specificity, positive and negative predictive values were calculated., Results: Fifty horses with 66 synovial structures were included in the study. Positive contrast radiography had a high specificity (86.4%), but only a moderate sensitivity (59.1%) for the identification of synovial infection. In addition, a low positive predictive value (68.4%) and high negative predictive value (80.9%) were observed in this population of horses., Main Limitations: Sensitivity, specificity and predictive values may differ between different synovial structures and cases. Different conclusions may be drawn from the results in a single population. Sensitivity and specificity of positive contrast radiography may also be influenced by different techniques used by examiners and by inherent characteristics of individual cases., Conclusions: Positive contrast radiography should be used for the investigation of potential synovial infection in horses with limb wounds, particularly if no synovial fluid sample for laboratory analysis can be obtained. However, it appears that positive contrast radiography is best used in combination with other tests to ensure that a correct and timely diagnosis is made., (© 2018 EVJ Ltd.)

There is an increasing biomechanical and anatomical understanding of the different types of meniscal lesions. Lesions of the posterior part of the medial meniscus in the meniscosynovial area have recently received increased attention. They generally occur in association with anterior cruciate ligament (ACL) injuries. They are often missed ("hidden lesions") due to the fact that they cannot be seen by routine anterior arthroscopic inspection. Furthermore, meniscosynovial lesions play a role in anteroposterior knee laxity and, as such, they may be a cause of failure of ACL reconstruction or of postoperative persistent laxity. Little information is available regarding their cause with respect to injury mechanism, natural history, biomechanical implications, healing potential and treatment options. This article presents an overview of the currently available knowledge of these ramp lesions, their possible pathomechanism, classification, biomechanical relevance as well as repair techniques.

Context: Hip arthroscopy is gaining popularity within the field of orthopaedic surgery. The development and innovation of hip-specific arthroscopic instrumentation and improved techniques has resulted in improved access to the hip joint and ability to treat various hip pathologies., Evidence Acquisition: Electronic databases, including PubMed and MEDLINE, were queried for articles relating to hip arthroscopy indications (1930-2017)., Study Design: Clinical review., Level of Evidence: Level 4., Results: Initially used as a technique for loose body removal, drainage/debridement of septic arthritis, and treatment of pediatric hip disorders, hip arthroscopy is currently used to treat various hip conditions. The recognition of femoroacetabular impingement (FAI) as a source of hip pain in young adults has rapidly expanded hip arthroscopy by applying the principles of osseous correction that were previously described and demonstrated via an open surgical dislocation approach. Hip pathologies can be divided into central compartment, peripheral compartment, peritrochanteric space, and subgluteal space disorders., Conclusion: Although hip arthroscopy is a minimally invasive procedure that may offer decreased morbidity, diminished risk of neurovascular injury, and shorter recovery periods compared with traditional open exposures to the hip, it is important to understand the appropriate patient selection and indications.

Background: Injuries penetrating synovial structures are common in equine practice and often result in septic synovitis. Significantly increased plasma levels of serum amyloid A (SAA) have been found in various infectious conditions in horses including wounds and septic arthritis. Plasma SAA levels were found to decrease rapidly once the infectious stimulus was eliminated. The purpose of the current study was to investigate the usefulness of serial measurements of plasma SAA as a monitoring tool for the response to treatment of horses presented with injuries penetrating synovial structures. In the current study plasma SAA concentrations were measured every 48 hours (h) during the course of treatment., Results: A total of 19 horses with a wound penetrating a synovial structure were included in the current study. Horses in Group 1 (n = 12) (injuries older than 24 h) only needed one surgical intervention. Patients in this group had significantly lower median plasma SAA levels (P = 0.001) between 48 h (median 776 mg/L) and 96 h (median 202 mg/L) after surgery. A significant decrease (P = 0.004) in plasma SAA levels was also observed between 96 h after surgery (median 270 mg/L) and 6 days (d) after surgery (median 3 mg/L). Four horses (Group 2) required more than one surgical intervention. In contrast to Group 1 patients in Group 2 had either very high initial plasma concentrations (3378 mg/L), an increase or persistently high concentrations of plasma SAA after the first surgery (median 2525 mg/L). A small group of patients (n = 3) (Group 3) were admitted less than 24 h after sustaining a wound. In this group low SAA values at admission (median 23 mg/L) and peak concentrations at 48 h after surgery (median 1016 mg/L) were observed followed by a decrease in plasma SAA concentration over time., Conclusions: A decrease in plasma SAA concentrations between two consecutive time points could be associated with positive response to treatment in the current study. Therefore, serial measurements of plasma SAA could potentially be used as an additional inexpensive, quick and easy tool for monitoring the treatment response in otherwise healthy horses presented with injuries penetrating synovial structures. However further studies will be necessary to ascertain its clinical utility.

The stem cells that safeguard synovial joints in adulthood are undefined. Studies on mesenchymal stromal/stem cells (MSCs) have mainly focused on bone marrow. Here we show that lineage tracing of Gdf5-expressing joint interzone cells identifies in adult mouse synovium an MSC population largely negative for the skeletal stem cell markers Nestin-GFP, Leptin receptor and Gremlin1. Following cartilage injury, Gdf5-lineage cells underpin synovial hyperplasia through proliferation, are recruited to a Nestin-GFP high perivascular population, and contribute to cartilage repair. The transcriptional co-factor Yap is upregulated after injury, and its conditional ablation in Gdf5-lineage cells prevents synovial lining hyperplasia and decreases contribution of Gdf5-lineage cells to cartilage repair. Cultured Gdf5-lineage cells exhibit progenitor activity for stable chondrocytes and are able to self-organize three-dimensionally to form a synovial lining-like layer. Finally, human synovial MSCs transduced with Bmp7 display morphogenetic properties by patterning a joint-like organ in vivo. Our findings further the understanding of the skeletal stem/progenitor cells in adult life.

When considering knee pain in runners, clinicians differentiate sources of symptoms and determine their cause. Knee problems arise when a runner increases the amount/frequency of the loading through the lower limb. The way the loading is distributed through the knee determines which tissues are abnormally loaded. Knee problems cannot be considered in isolation, requiring a thorough investigation of static and dynamic lower limb mechanics, and footwear and surfaces. This article examines potential sources of knee pain and explores the role of the infrapatellar fat pad and synovial plica in the mechanics of the knee and its involvement in knee symptoms., (Copyright © 2016 Elsevier Inc. All rights reserved.)

This review article discusses the magnetic resonance imaging (MRI) features and pathological changes of muscles, nerves and the synovial lining of the elbow joint. Typical imaging findings are illustrated and discussed. In addition, the cross-sectional anatomy and anatomical variants, such as accessory muscles and plicae are discussed. Injuries of the muscles surrounding the elbow joint, as well as chronic irritation are particularly common in athletes. Morphological changes in MRI, for example tennis or golfer's elbow are typical and often groundbreaking. By adapting the examination sequences, imaging planes and slices, complete and incomplete tendon ruptures can be reliably diagnosed. Although the clinical and electrophysiological examinations form the basis for the diagnosis of peripheral neuropathies, MRI provides useful additional information about the precise localization due to its high resolution and good soft tissue contrast and helps to rule out differential diagnoses. Synovial diseases, such as inflammatory arthritis, proliferative diseases and also impinging plicae must be considered in the MRI diagnostics of the elbow joint.

The study described here tested the hypothesis that early intra-articular inflammation is associated with the development of post-traumatic osteoarthritis (PTOA) in a sheep model. We extended previously published work in which we investigated joint gross morphology and synovial mRNA expression of inflammatory and catabolic molecules 2 weeks after anatomic Anterior cruciate ligament (ACL) autograft reconstructive surgery (ACL-R). The same variables have been analyzed at 20 weeks post surgery together with new experimental variables at both time points. Animals were sacrificed at 20 weeks post ACL-R surgery and their joints graded for signs of PTOA. Synovial samples were harvested for histological grading plus mRNA and protein analysis for a panel of inflammatory and catabolic molecules. The mRNA expression levels for this panel plus connective tissue matrix turnover molecules were also investigated in cartilage samples. Results of gross morphological assessments at 20 weeks post surgery showed some changes consistent with early OA, but indicated little progression of damage from the 2 week time point. While significant alterations in mRNA levels for synovial inflammatory and catabolic molecules were detected at 2 weeks, values had normalized by 20 weeks. Similarly, all mRNA expression levels for inflammatory and catabolic molecules in articular cartilage had returned to normal levels by 20 weeks post ACL-R surgery. We conclude that synovial inflammatory processes are initiated very early after ACL-R surgery and may instigate events that lead to the gross cartilage and joint abnormalities observed as early as 2 weeks. However, the absence of sustained inflammation and joint instability may prevent OA progression., (Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Purpose: Cellular apoptosis might be an important molecular event in the middle or late healing periods of intrasynovial tendons, but this has not been studied. We aimed to investigate cellular apoptosis and corresponding cellular proliferation in the middle and late healing stages of intrasynovial tendons., Methods: The flexor digitorum profundus tendons of 48 long toes (24 chickens) were completely transected within the sheath region and were repaired surgically. At days 28, 42, 56, and 84 after surgery, tendons were harvested and sectioned. In situ terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was performed to detect apoptotic cells. The sections were stained immunofluorescently with antibodies to proliferating cell nuclear antigen to assess proliferation and to Bcl-2 (an anti-apoptotic protein). Positively stained tenocytes were counted, and their distributional differences were verified in 3-dimensional images., Results: The repaired intrasynovial tendons exhibited generally greater apoptosis in the surface region than in the core. The differences were more remarkable in the extended region than in the junction region of the cut tendon. At the core of the junction site, apoptosis of tenocytes was pronounced at all time points, but it was less severe at the core of the extended region. The proliferating cell nuclear antigen-positive and Bcl-2-positive tenocytes decreased significantly and continually at days 28, 42, and 56, respectively; these tenocytes were at a minimum at days 56 and 84., Conclusions: Apoptotic changes of tenocytes are most marked in the surface region and in the junction region of the healing tendon in the middle and late healing stages. Apoptosis in the core is less dramatic compared to that in the surface in the extended tendon regions. Cellular proliferation declines drastically and is minimal at days 56 and 84., Clinical Relevance: Tenocyte apoptosis in the middle and late stages might be an important event contributing to intrasynovial tendon remodeling, which affects the healing strength and formation of adhesions., (Copyright © 2012 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.)

The synovial folds of the cervical spine are regarded as a potential source of neck pain and headache, especially following whiplash injury. Damage to the synovial folds following motor vehicle trauma has been well documented in post-mortem studies. However, methods of identifying injury to the synovial folds in the survivors of motor vehicle trauma have proven elusive to date. Recently, it has been made possible to image the synovial folds in vivo using magnetic resonance imaging. This now makes it feasible to investigate the potential involvement of synovial folds in the generation of neck pain and headache and its relief using spinal manipulation. This paper reviews critically the morphology of the synovial folds of the cervical spine that underpins the hypotheses proposed to explain their functional and clinical significance and a new system of naming and classifying the synovial folds is presented. Although there is some evidence to support the contribution of the synovial folds to neck pain, several theories have little or no support and require investigation and further evaluation. These findings have implications for understanding the anatomical basis of neck pain and headache and the rationale for the use of spinal manipulation in their management., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The underlying etiology of anterior knee pain has been extensively studied. Despite many possible causes, often times the diagnosis is elusive. The most common causes in the young athlete are osteosynchondroses, patellar peritendinitis and tendinosis, synovial impingement, malalignment, and patellar instability. Less common causes are osteochondritis dissecans and tumors. It is always important to rule out underlying hip pathology and infections. When a diagnosis cannot be established, the patient is usually labeled as having idiopathic anterior knee pain. A careful history and physical examination can point to the correct diagnosis in the majority of cases. For most of these conditions, treatment is typically nonoperative with surgery reserved for refractory pain for an established diagnosis.

Carpal tunnel syndrome (CTS) is a nerve entrapment disease, which has been extensively studied by the engineering and medical community. Although the direct cause is unknown, in vivo and in vitro medical research has shown that tendon excursion creates microtears in the subsynovial connective tissue (SSCT) surrounding the tendon in the carpal tunnel. One proposed mechanism for the SSCT injury is shearing, which is believed to cause fibrosis of the SSCT. Few studies have reported quantitative observations of SSCT response to mechanical loading. Our proposed model is a 2-D section that consists of an FDS tendon, interstitial SSCT and adjacent stationary tendons. We believe that developing this model will allow the most complete quantitative observations of SSCT response to mechanical loading reported thus far. Boundary conditions were applied to the FEA model to simulate single finger flexion. A velocity was applied to the FDS tendon in the model to match loading conditions of the documented cadaver wrist kinematics studies. The cadaveric and FEA displacement results were compared to investigate the magnitude of stiffness required for the SSCT section of the model. The relative motions between the model and cadavers matched more closely than the absolute displacements. Since cadaveric models do not allow identification of the SSCT layers, an FEA model will help determine the displacement and stress experienced by each SSCT layer. Thus, we believe this conceptual model is a first step in understanding how the SSCT layers are recruited during tendon excursion., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Objective: The aim of our study was to examine the effect of suction drains on knee after arthroscopic partial meniscectomy with partial fat pad removal or synovectomy., Methods: We performed arthroscopic partial meniscectomy for posterior tears of the medial meniscus and partial fat pad or synovium shaving in 72 patients. Following surgery, a suction drain was not used in 40 patients (Group A) and used in 32 (Group B). Both groups were similar in terms of age, gender, and total operation time. The patients were evaluated at 1, 2, and 4 weeks postoperatively for the presence of a knee effusion., Results: No significant difference was observed in the grade of effusion and the average percent change in the effusion grade between Groups A and B at 1, 2, and 4 weeks postoperatively., Conclusion: Use of a suction drain did not influence the postoperative effusion or the clinical course of the effusion after arthroscopic partial meniscectomy with partial fat pad removal or synovectomy.

Tendon injury frequently results in the formation of adhesions that reduce joint range of motion. To study the cellular, molecular, and biomechanical events involved in intrasynovial tendon healing and adhesion formation, we developed a murine flexor tendon healing model in which the flexor digitorum longus (FDL) tendon of C57BL/6 mice was transected and repaired using suture. This model was used to test the hypothesis that murine flexor tendons heal with differential expression of matrix metalloproteases (MMPs), resulting in the formation of scar tissue as well as the subsequent remodeling of scar and adhesions. Healing tendons were evaluated by histology, gene expression via real-time RT-PCR, and in situ hybridization, as well as biomechanical testing to assess the metatarsophalangeal (MTP) joint flexion range of motion (ROM) and the tensile failure properties. Tendons healed with a highly disorganized fibroblastic tissue response that was progressively remodeled through day 35 resulting in a more organized pattern of collagen fibers. Initial repair involved elevated levels of Mmp-9 at day 7, which is associated with catabolism of damaged collagen fibers. High levels of Col3 are consistent with scar tissue, and gradually transition to the expression of Col1. Scleraxis expression peaked at day 7, but the expression was limited to the original tendon adjacent to the injury site, and no expression was present in granulation tissue involved in the repair response. The MTP joint ROM with standardized force on the tendon was decreased on days 14 and 21 compared to day 0, indicating the presence of adhesions. Peak expressions of Mmp-2 and Mmp-14 were observed at day 21, associated with tendon remodeling. At day 28, two genes associated with neotendon formation, Smad8 and Gdf-5, were elevated and an improvement in MTP ROM occurred. Tensile strength of the tendon progressively increased, but by 63 days the repaired tendons had not reached the tensile strength of normal tendon. The murine model of primary tendon repair, described here, provides a novel mechanism to study the tendon healing process, and further enhances the understanding of this process at the molecular, cellular, and biomechanical level., (Copyright 2008 Orthopaedic Research Society)

Unicondylar knee arthroplasty (UKA) is a well-established treatment option for unicompartmental knee arthrosis. Although UKA achieves high success rates, surgeons should be aware of many potential sources of persistent postoperative pain. Common causes include septic or aseptic loosening, a loose body, implant failure, and chronic regional pain syndrome. Tibial plateau stress fracture, meniscus rupture, and cement extrusion have also been reported as infrequent causes of persistent pain. We encountered 2 patients in whom persistent pain after UKA was attributed to synovial impingement mimicking a meniscus tear, and we refer to this as pseudomeniscal synovial impingement. This article presents the clinical histories and histologic findings of 2 patients fitted with a mobile-bearing UKA system and a fixed-bearing UKA system, respectively. These patients were successfully treated by arthroscopic excision.

Post-steroid septic arthritis can be treated with irrigation pump assisted arthroscopic synovectomy. The high-intra-articular fluid pressures can force the pyogenic fluid into a pre-existing Baker's cyst. The cyst can rupture and with the pre-existing steroid induced immune-suppression, the calf abscess will be hard to control. Therefore, thorough investigation with an ultrasound-guided aspiration followed by an early drainage of the collection is warranted and mandatory. Close monitoring for the development of a deep thrombosis of the popliteal vein is required.

Objective: The pectinofoveal fold is an intraarticular structure of the hip that has had only limited study in the clinical and anatomic literature. This fold may resemble a hip plica; however, symptomatic hip plicae are now being recognized and treated at hip arthroscopy. We wished to determine the frequency and appearance of the pectinofoveal fold on hip MR arthrography. By defining the variations in its appearance, the normal pectinofoveal fold can be distinguished from pathologic hip plicae., Materials and Methods: One hundred fifty-two hip MR arthrography examinations of patients who subsequently underwent hip arthroscopy were retrospectively reviewed. Each MR examination was reviewed for the presence of a pectinofoveal fold. If present, the fold was measured in the anteroposterior, mediolateral, and superior-inferior dimensions; evaluated for smooth or irregular contour; and evaluated for a femoral or capsular site of insertion., Results: The pectinofoveal fold was visualized on hip MR arthrograms in 144 of the 152 (95%) patients and visualized at hip arthroscopy in 150 of the 152 (99%) patients. The average thickness of the fold was 2.6 mm (range, 1-13 mm) in the mediolateral dimension and 17 mm (range, 1-32 mm) in the anteroposterior dimension. The average length of the fold in the superior-inferior dimension was 23.3 mm (range, 7-44 mm). The pectinofoveal fold had a smooth contour in 75 of the 144 (52%) patients with examinations that showed the fold and an irregular contour in 69 of 144 (48%) patients. The fold was found to insert onto the capsule in 108 of 144 (75%) patients and onto the femur in the remaining 36., Conclusion: The pectinofoveal fold should almost always be visualized at MR arthrography. The fold can have various appearances and attachment sites, and these normal variations should not be mistaken for fold abnormalities. These findings should be useful in distinguishing this normal structure from normal and pathologic plicae.

We aimed to review the results of subtotal arthroscopic resection of symptomatic type D medial plica. We retrospectively evaluated 23 knees with symptomatic type D medial plica in 22 patients without other intra-articular pathology. All patients complained of chronic knee pain that had not been alleviated by medical treatment or physical therapy. In only three (13%) of the patients studied was the plica diagnosed pre-operatively with magnetic resonance imaging. The type D medial plicae in our series were classified as fenestrated (14 knees), torn (5 knees), or reduplicated (4 knees). Fibrotic changes in the plicae and degenerative changes on the medial femoral condyle were found in 16 knees Patellofemoral chondromalacia was present in three knees Arthroscopic partial resection was performed in all patients. Comparative Lysholm Knee Scale scores before and after surgery revealed a significant clinical improvement (pre-operative status, 67.19 +/- 8.05 vs. post-operative status, 90.57 +/- 9.80; P < 0.001). Type D medial plica should be considered as a possible cause of chronic knee pain. Arthroscopic partial resection of the plicae in symptomatic patients gives satisfactory results.

We report a case of plant thorn injury-induced tenosynovitis of the index finger of the left hand that was cured after surgical removal of the foreign body and partial synovectomy. We review current literature on this infrequently reported topic. Pathologically, thorn synovitis represents a foreign body reaction to retained plant material and is mostly aseptic. The presentation is delayed with the history of preceding injury often forgotten, and the diagnosis thus relies on careful elicitation of history. Imaging may be helpful to localize the plant material when the history is not clear. When possible, removal of the foreign material leads to complete remission, although some patients need partial or total synovectomy.

Plicae are synovial folds, classified according to their anatomical relationship to the patella. The medial patellar plica is normally asymptomatic, but it may cause symptoms when it becomes thickened and fibrotic. We describe three cases of bucket-handle tear of the medial patellar plica. They all suffered from anterior knee pain and clicking. Our cases' symptoms began when they incurred twisting injuries to the knee; therefore, we think that they had an asymptomatic plica first. Pain and clicking began because of the bucket-handle portion rubbed over the medial femoral condyle with knee flexion, and they improved after resection of the bucket-handle portion. Consequently, we think that medial patellar plica can be symptomatic not only when it becomes thickened or fibrotic but also when a bucket handle tear occurs.

This study examined the expression of inducible nitric oxide synthase (iNOS) and transforming growth factor-beta (TGF-beta) in macrophage infiltrates within crush-injured digital flexor tendon and synovium of control rats and rats treated with N(G)-nitro-1-arginine methyl ester (L-NAME) (5 mg/kg). Release of TGF-beta from organ cultures of tendon, muscle, and synovium, and the effects of L-NAME treatment (in vitro and in vivo), on adhesion of peritoneal macrophages to epitenon monolayers were also investigated. The results showed that during normal tendon healing the levels of TGF-beta are high at first and gradually decrease after 3 weeks of injury to slightly above control uninjured levels. However, when L-NAME was administered at the time of injury, the macrophage infiltrates were expressing high levels of TGF-beta even at 5 weeks after the injury, with no evidence of reduction. In the standard injury, iNOS activity was greatest at the acute phase of the inflammatory response and then gradually returned to normal. Treatment with L-NAME, however, resulted in inhibition of iNOS activity at 3 days and a reduction in the activity at the later time points examined after injury. We also found greatly increased levels of adhesion of peritoneal macrophages from L-NAME-treated rats to epitenon monolayers in vitro, which reflect a chronic imbalance in expression of TGF-beta, which is overexpressed, and nitric oxide, which is underexpressed. The results of the current study show that formation of nitric oxide is an important event in the course of tendon healing since its inhibition results in chronic inflammation and fibrosis due to an imbalance in TGF-beta expression in vivo.

This article reviews some of the conditions about the elbow in athletes or active individuals. The conditions discussed are synovial plica of elbow, radiocapitellar arthritis, congenital dislocation of the radial head, radio-ulnar synostosis, hemophilia and rheumatoid arthritis. In the past, people who had these conditions were instructed to avoid athletic activities; however, they are now being counseled to remain active and to try to exercise on a regular basis.

Objective: Injury to the infrapatellar plica (ligamentum mucosum) has not been previously described in the radiology literature to our knowledge. This article shows the MR imaging appearance of injury to the infrapatellar plica., Conclusion: Injury to the infrapatellar plica is uncommon but should be considered as a potential source of knee pain, especially if no other evidence indicates internal derangement. MR imaging can reveal a typical appearance for infrapatellar plica injury.

Background: Electron microscopy was used to examine the histologic effect of trauma on the rat temporomandibular joint synovial membrane., Methods: Trauma to the TMJ in male Wister rats (100-200 g) was introduced through repeated forced condylar hypermobility. Ultrastructural observations were made 5 days and 6 weeks after the trauma., Results: The early response of the synovial membrane was synovial hyperplasia, type A synovial cell loss, dilation of the r-ER in the type B synovial cells and fibrin deposition on the synovial surfaces. The late response included degeneration of synovial cells with swollen mitochondria and cell projections, and cell fragmentation. Large amount of fibrin deposition on opposing surface layers was also noticed., Conclusion: The type A cell loss and fibrin deposition followed by the occurrence of fibrinous materials at opposing surface layers of the synovial membrane suggest that traumatic synovitis causes synovial adhesions.

Medial plica syndrome is usually a rare cause of anterior knee pain, but in adolescent athletes it is more common. A prospective investigation of clinical criteria for the diagnosis of medial plica syndrome was carried out. Investigating the stress test for the diagnosis of medial plica syndrome, we used active extension as a kick test and flexion to test blocking of swinging of the shank. The aim of this investigation was to examine these two new tests. The tests we used improved the accuracy of the clinical examination and allowed diagnosis of the symptomatic medial plica.

The fenestra type of infrapatellar plica was noted arthroscopically in a 57-year-old patient with flexion contracture of the knee. It was found to be thickened and fibrotic and to have lost its normal elasticity. The pathologic plica was impinged at the intercondylar notch and trochlea, blocking further extension beyond 25 degrees of knee flexion. After excising the plica, the knee gained a further extension of 17 degrees; however, full extension could not be obtained. The knee gained full extension after notchplasty on the roof at 2 months postoperatively. This is the first report of a pathological infrapatellar plica in an older patient.

Purpose: We report a new method of describing and recording chondral lesions of the knee at arthroscopy in order to permit a more accurate and meaningful analysis of patterns of articular cartilage damage., Type of Study: Case series study., Methods: Data were collected prospectively at 1,000 consecutive arthroscopies by the senior author and chondral lesions were recorded on anatomic articular maps divided into different functional zones. Ten zones on the femur were determined by tibiofemoral weight-bearing and flexion horizons (namely the 0 degrees, 45 degrees, 90 degrees, and 120 degrees horizons as they pass the anterior meniscosynovial junction). Ten zones were determined on the tibia, principally by meniscal relations, and 6 zones on the patella. This allowed the size, Outerbridge grade, and location to be analyzed in relation to mechanism, chronicity, and associated intra-articular pathologies. The recording methods were tested for interobserver reproducibility in 50 subsequent cases at the same arthroscopy by 2 independent observers. The results were analyzed by a third person, and showed a relatively small interobserver error of 7.2% for size for a set of grade 3 and 4 lesions and only a 3% error for site. The Fisher exact test was used. The data sheets were entered onto a computer spreadsheet database using standard software (Excel; Microsoft, Redmond, WA) to permit analysis of the data., Results: There were 1,553 chondral lesions in 853 patients correlated with associated lesions, including 356 meniscal lesions, 230 ligamentous injuries, 440 synovial lesions, and other pathologies. High degrees of correlation have been found between specific lesions and their opposing surfaces and the progression of these with time., Conclusions: The problem of precision of localization of articular lesions in the knee has been recently acknowledged by the International Cartilage Research Society (ICRS). However, such recording ought to take into account both function and contact with other structures. This would appear essential in the assessment of prognosis and comparisons between different treatment regimes.

Summary: This is a retrospective review of the results of 40 patients with 44 partial stable meniscal tears who were treated with parameniscal synovial abrasion at the time of anterior cruciate ligament reconstruction. There were 19 medial meniscal (MM) tears and 25 lateral meniscal (LM) tears. Meniscal tear morphology included 33 single longitudinal tears (18 MM, 15 LM), 10 double longitudinal tears (1 MM, 9 LM), and 1 radial tear (LM). All 44 tears were located in the posterior horn or posterior junction of the meniscus. Rim width was 3 mm in 15 tears. In this study, failure was defined as a symptomatic meniscal tear requiring subsequent surgery. The overall failure rate at an average follow-up of 3.3 years was 11% (5 of 44). Four failures occurred in the MM (21% of total MM tears) and 1 failure occurred in the LM (4% of total LM tears). The median time to failure was 12 months with 3 of 5 failures occurring secondary to a significant reinjury. We looked at the effect of 8 factors on overall failure rate. Although statistical validity was not established in this small patient population, we did observe a higher failure rate for stable MM tears. Our study supports the small amount of literature that shows a high clinical success rate with observation of stable LM tears identified at the time of anterior cruciate ligament reconstruction. However, the much higher failure rate of stable MM tears raises concern. This difference is explained by biomechanical and clinical studies showing that the MM develops higher stresses than the LM with loading. Based on this work, we believe that stable longitudinal MM tears have a higher propensity to fail over time by propagation of the tear and are better managed with meniscal repair.

Objective: To define the pattern of mRNA expression of all human matrix metalloproteinases (MMPs) described to date in rheumatoid arthritis (RA) and traumatic synovial membrane, in order to differentiate between a physiological tissue remodelling pattern and that associated with inflammatory tissue destruction., Methods: Analysis of SwissProt protein and EMBL/GenBank nucleotide sequence banks, protein sequence alignment, reverse transcriptase-polymerase chain reaction and nucleotide sequencing were used., Results: MMP-2 (gelatinase A), MMP-3 (stromelysin-1), MMP-11 (stromelysin-3) and MMP-19 were constitutively expressed. MMP-1 (fibroblast type collagenase), MMP-9 (gelatinase B) and MMP-14 (MT1-MMP) were expressed in all RA, but only in 55-80% of trauma samples. MMP-13 (collagenase-3) and MMP-15 (MT2-MMP) were expressed exclusively in RA (80-90% of the samples). MMP-20 (enamelysin) was absent and MMP-8 (collagenase-2) was rarely found in RA or trauma. All other MMPs (-7, -10, -12, -16, -17) had an intermediate pattern of expression., Conclusions: Some MMPs without interstitial collagenase activity seem to have a constitutive pattern of expression and probably participate in physiological synovial tissue remodelling. Some MMPs are exclusively associated to RA synovitis, for example, MMP-13, which preferentially degrades type II collagen and aggrecan, and MMP-15, which activates proMMP-2 and proMMP-13 and is involved in tumour necrosis factor alpha processing. This clear cut rheumatoid/inflammatory MMP profile, more complex than has been previously appreciated, may facilitate inflammatory tissue destruction in RA.

Synovial membrane biopsies were collected from 32 dogs with spontaneous cranial cruciate ligament rupture and seven control dogs. The subclasses of immunoglobulins in the synovial membrane of both the diseased and control dogs were examined with immunohistochemistry in combination with image analysis. IgG deposition was four-fold higher and IgM was eight-fold higher in dogs with spontaneous cranial crucial ligament (CrCL) rupture. These findings support the theory that there is an immune component to the inflammation associated with canine CrCL rupture. Further investigation is required to determine if these immune or inflammatory responses in CrCL rupture joints are the primary factor in ligament rupture or if they develop secondary to ligament rupture and instability.

This article explores arthrography of the knee beginning with a brief historical perspective of conventional knee arthrography and culminating in direct and indirect MR arthrography of the knee. This article discusses the advantages of MR arthrography in the radiologic assessment of the postoperative meniscus, abnormalities of articular cartilage, and synovial-based processes.

Ankle tenography is an easily learned technique for the treatment of tenosynovitis. This article describes the procedure in detail and discusses the indications and contraindications for tenography. The anatomy of the ankle tendons is briefly reviewed. This article familiarizes radiologists with this minimally-invasive therapeutic modality so that they can offer it as an option for their referring physicians, who often have few other choices when it comes to managing patients with chronic ankle pain.

A series of 18 patients aged 21-45 years treated due to nerve injuries within popliteal space in Traumatology and Orthopaedics Department of MSWIA Hospital in Bydgoszcz between 1992 and 1994 has been studied. In 16 patients (88.8%) common peroneal nerve was involved, in one patient (5.6%) tibial nerve and both nerves were injured in 1 patient also (5.6%). In 14 cases (77.8%) neuropraxis was diagnosed, in 2 cases (11.1%) axonotmesis and neurotmesis in remaining 2 cases. Patients with neuropraxis and axonotmesis type of injury regained complete function after conservative treatment of 4 weeks to 3 months duration. Those with neurotmesis have been operated on. The patient with injury to both nerves regained tibial nerve function. No return of function has been achieved in the patient with peroneal nerve neurotmesis.

A 6-year-old Quarter Horse gelding with acute onset of a grade-4/5 lameness of the left forelimb 21 days after an encounter with a porcupine was examined. Quills had been removed by the referring veterinarian, and the horse had been treated with antibiotics and hydrotherapy for 14 days. The horse was pyretic and had effusion in the digital synovial sheath. Signs of pain were elicited on palpation of the area. A tentative diagnosis of septic tenosynovitis caused by a porcupine quill was made. Exploratory tenoscopy revealed large amounts of fibrin in the sheath and a 1.2-cm quill. Bacteriologic culture of synovial fluid yielded a pure growth of Staphylococcus aureus. The horse improved dramatically after tenoscopic removal of the quill, debridement of fibrin, and lavage to dilute inflammatory mediators and bacteria, debridement of fibrin, discovery and removal of a quill, and complete evaluation of the sheath for prognostic purposes. Tenoscopy can provide a means for direct observation and enhance the ability of clinicians to debride a septic synovial sheath in a minimally invasive manner.

Ruptures of the cruciate ligaments continue to pose both diagnostic and therapeutic problems. On the basis of structural analysis of MR images obtained after the accident and the results of conservative treatment, it can be shown that function healing of the rupture can result, when, for example, the synovial membrane (capsule) is preserved (70%). It proved possible to show and objectify this using MRI and measurements.

Purpose: The etiology of pathological media plica of the knee is unknown. We describe two cases of large, torn medial plicae. The cases help understand the etiology and avoid diagnostic pitfalls., Case Summary: Two patients with medial knee pain and pseudolocking were found to have "bucket-handle" tears of the large medial plicae. The pseudolocking phenomenon was observed arthroscopically in an effort to understand causation., Discussion: Direct trauma and lateral traction are hypothesized to lead to thickened, pathologic medial plicae. A history of locking usually leads the examiner to look for torn menisci or loose bodies. These cases show that a medial plica with a longitudinal split can behave in a manner that can be mistaken for locking. The mechanism by which this occurs gives insight about the condition's etiology., Relevance: Present treatment for painful medial plica is physical therapy, occasional corticosteroid injection, and arthroscopic excision when these efforts fail. Based on the evidence from these cases, a reasonable first step after diagnosing a traumatic, painful medial plica might be to selectively strengthen the vastus medialis obliquus.

Recurrent haemarthros is described as consequence of cruciate ligament repair. The main cause of haemarthros is described after unisometric fixation of the ligaments which leads to the rupture of the synovia membrane. This is a case report of a young man, who suffered from recurrent haemarthros for several years although he has intensively examined by radiological and arthroscopical means. It was falsely presumed to be a muscular arthrophy. The cause, however, was found in a wire suture, which was used to fix the anterior cruciate ligament in the femoral bone. This suture was laying under the synovia within the ligament and there fore could be seen and taken away arthroscopically only after total synovialectomy.

Objective: As a model system to understand the efficacy of patients with glucocorticoid (GC) treatment of joint inflammation of rheumatoid arthritis, we stimulated confluent rabbit synovial fibroblasts in culture with interleukin 1 beta (IL-1 beta) and studied the effects of dexamethasone (Dex)., Methods: Twenty-four h after IL stimulation Dex was added and the response of cells to Dex was estimated by [3H]thymidine uptake, cell count and lactate dehydrogenase release. Cellular and nuclear binding of [3H] Dex as well as the DNase sensitivity of isolated nuclei were estimated., Results: Dex strongly inhibited the [3H]thymidine uptake by the stimulated cells in a dose dependent manner with Ki of lower than 10(-12) M, whereas it only slightly inhibited the unstimulated cells. With stimulation the sensitivity of cells increased 10-fold as estimated by lactate dehydrogenase release and 85-fold by counting the final cell density. We found also a 5-fold increase in the DNase I hypersensitive sites in the nuclei and a 2 to 3-fold increase in the cellular as well as the nuclear Dex binding sites following stimulation., Conclusion: In addition to the well documented inhibition of degradative enzyme production by the stimulated synovium, the efficacy of GC treatment of patients could be explained also on the basis of the sensitization of stimulated synovium to the GC mediated injury.

Plant thorn synovitis is an overlooked cause of monoarthritis, with difficulties in diagnosis and treatment (1). We report on a case of thorn induced synovitis, not confirmed by histopathology, but strongly suspected by magnetic resonance imaging (MRI), that visualizes the foreign body (first case reported).

Thirty victims of blunt cervical trauma, who did not survive (acute death group), were studied at autopsy as were 11 patients who survived trauma for more than 1 month and ten controls without any known cervical trauma. All specimens were sagitally sectioned in 2-mm slices and carefully examined for injuries to the lateral parts of the atlanto-axial joints. In the acute death group, five cases showed a rupture of the joint capsule, three of these with a massive hemarthrosis. In 17 cases there was bruising around the second cervical spinal nerve. Bruising of the intra-articular synovial fold was present in 15 cases, the posterior synovial fold being most commonly affected. There were five intra-articular fractures of the lateral masses, in three cases combined with a dens fracture. In two cases a bone fragment from the fracture compressed and obliterated the lumen of the vertebral artery. The findings are discussed in relation to pain after cervical trauma.

We demonstrated that vascular endothelial cells mechanically wounded by scraping from the substratum were able to release growth promoting factors for synovial cells as well as for endothelial cells. The wounded endothelial cell conditioned medium stimulated the proliferation of synovial cells derived from different human donors dose dependently and induced transit of growth arrested synovial cells (predominant in the G0 and G1 phases), through the S phase and into the G2 and M phases. When the wounded endothelial cell conditioned medium was applied to heparin-sepharose columns, mitogenic activity was eluted with 2.0 M NaCl. The mitogenic activity in wounded endothelial cell conditioned medium, which was heat sensitive, was inhibited by protamine sulfate and a specific mouse monoclonal antibody against basic fibroblast growth factor (bFGF). Our results are evidence that the wounded endothelial cell conditioned medium contained growth promoting factors for synovial cells, including bFGF. We also showed the presence of bFGF in the endothelial cells of the small blood vessels and stromal synovial fibroblast-like cells in patients with rheumatoid arthritis (RA). Our results suggest that the endothelial cells in the luxuriant capillaries in the synovial tissues from patients with RA may have a critical role in the stimulation of neighboring synovial cell proliferation, resulting in pronounced synovial hyperplasia.

A neodymium yttrium aluminum garnet (Nd:YAG) laser inserted through an operating arthroscope was used to introduce applied energy to synovial tissues, articular discs, and bone in the temporomandibular joint of mongrel dogs. Arthroscopic inspection of the wounds was performed at 1 and 2 weeks postoperatively. The animals were killed and the temporomandibular joints were examined grossly and histologically to determine the extent of injury and healing. The results show that laser wounds of bone and articular disc undergo no repair, whereas laser wounds of synovium show rapid repair. Laser damage to condylar marrow under an articular disc wound was unexpectedly found.