Micromorphology and topography of tarsal joint capsule's vascular elements in cats and dogs.

Both cats and dogs belong to animals with the same type of limb support but have different nature of movement. Despite belonging to digitigrade animals, cats and dogs have a different nature of motion. While moving, the medial joint surface in cats and lateral surface in dogs carry the larger pressure. The aim of the study was to compare the similar surfaces of the cat's and dog's tarsal joint capsule and to detect differences in its histostructure and vascularisation. For the study, we used the capsule of the tarsal joint of five cats and five dogs dissected with accordance to anatomical surfaces. Sections of the capsule joint were stained with haematoxylin-eosin. The sections were examined with a microscope at magnification ×250 and ×400. The statistical analysis of the results was done using Student's t test. During the research, a difference in histostructure and vascularisation of tarsal joint capsule in cats and dogs on respective surfaces were found. The medial surface of the tarsal joint capsule was the most saturated with hemomicrocirculatory bed structures in cats, whereas this was the lateral surface in dogs. The most active metabolic processes also take place in these areas of the joint capsule, which is important to know when prescribing therapeutic procedures and determining an optimal surgical access.

Treatment for proximal pole scaphoid nonunion with capsular-based vascularized distal radius graft.

PURPOSE: We retrospectively reviewed the results of 89 patients with proximal pole scaphoid nonunion, 58 with avascular necrosis, treated with a capsular-based vascularized distal radius graft. METHODS: Seventy-one male and eighteen female patients with symptomatic nonunion at the proximal pole of the scaphoid were included in this study. No patient had a humpback deformity. In all patients, the vascularized bone graft was harvested from the dorsum of the distal radius and was attached to a capsular flap of the dorsal wrist capsule. After fixation of the scaphoid with a small cannulated screw, the graft was inserted press-fit into the scaphoid trough in the nonunion site. Supplementary fixation of the graft with a microsuture anchor into the scaphoid was used in 66 patients. RESULTS: At a mean time of 12.3 weeks (range 6-24) after surgery, solid union was achieved in 76 of 89 patients (49 of 58 with avascular necrosis). Eleven patients had persistent nonunion and two fibrous union as determined by CT scan. Sixty-six of the patients with solid bone union were completely pain free, and ten complained of slight pain with strenuous activities. No donor site morbidity was observed. CONCLUSIONS: The capsular-based vascularized bone graft from the distal radius is a reliable alternative technique for scaphoid nonunions. It is a simple and expedient harvesting technique without the need for a microsurgical anastomoses. The supplemental fixation with a microsuture anchor eliminates the risk of graft displacement.

The glenocapsular ligament and the posterosuperior part of the joint capsule of the shoulder are well vascularized.

PURPOSE: A detailed structural anatomy of the posterosuperior shoulder capsule and "glenocapsular ligament" is still rather unknown. The purpose of this study was meticulously to investigate and describe the structure and blood supply of the glenocapsular ligament on the posterosuperior shoulder joint capsule. METHOD: Sixteen fixed and twelve fresh cadaveric shoulder specimens with a mean age of 73.4 (±6.4) years were analysed. Dissection without arterial injection was performed on the 16 fixed specimens-using an alcohol-formalin-glycerol solution. Before dissection, the 12 fresh specimens received of arterial injection a 10% aqueous dispersion of latex solution. After the injection, these shoulders were also fixed in an alcohol-formalin-glycerol solution. RESULTS: The glenocapsular ligament was found in all 28 specimens. Single or double parallel-running bundles of connective tissue fibres were found to form a capsular-ligamentous structure on the posterosuperior part of the joint capsule. One part of the ligament was mediosuperior, another posterosuperior. The mediosuperior part varied in shape, and in 12 of 28 cases, it was absent. The glenocapsular ligament arose from the supraglenoid tubercle and posterior part of the collum scapulae and inserted into the semicircular humeral ligament. The posterior ascending branch of the circumflex scapular artery directly fed small branches laterally and medially to the joint capsule, supplying the glenocapsular ligament and the deep layer of the joint capsule. CONCLUSION: The glenocapsular ligament is a constant anatomical structure that consists of one or two different parts. The glenocapsular ligament and the posterosuperior part of the joint capsule appear well vascularized via the posterior ascending branch of the circumflex scapular artery. CLINICAL RELEVANCE: It is the hope of the authors that this anatomical study can help surgeons who perform open or arthroscopic surgery to the posterior part of the shoulder. Knowledge of the vascular anatomy presented in this study may be especially important when incisions are made to the posterior part of the shoulder, and should minimize the risk of complications.

Increased blood flow in the anterior humeral circumflex artery correlates with night pain in patients with rotator cuff tear.

BACKGROUND: Night pain is a particularly vexing symptom in patients with rotator cuff tear. It disturbs sleep and decreases quality of life, and there is no consensus regarding its etiology. Based on arthroscopic surgical observations of synovitis around the rotator interval or capsule surface in rotator cuff tear, we hypothesized that blood flow from the artery feeding the capsule increases blood supply to the synovium. This study aimed to investigate the relationship between blood flow and night pain using pulse Doppler ultrasonography. METHODS: A series of 47 consecutive patients with rotator cuff tear was evaluated. The peak systolic velocity and resistance index of blood flow in the ascending branch of the anterior humeral circumflex artery were evaluated using pulse Doppler ultrasonography. We also investigated 20 normal shoulders in healthy volunteers. The peak systolic velocity and resistance index were compared between affected and unaffected sides in patients and between dominant and nondominant sides in controls. RESULTS: Anterior humeral circumflex artery peak systolic velocity and resistance index did not differ between sides in control subjects or in patients with rotator cuff tear without night pain. However, anterior humeral circumflex artery peak systolic velocity and resistance index did differ significantly between sides in patients with rotator cuff tear with night pain. CONCLUSIONS: This study revealed anterior humeral circumflex artery hemodynamics in patients with rotator cuff tear and normal subjects using Doppler ultrasonography. Night pain, particularly involving aching, appears to be related to the hemodynamics. These findings suggest that investigating the hemodynamics of patients with rotator cuff tear with night pain may lead to greater understanding of the etiology of this symptom.

Distribution of sensory nerve endings around the human sinus tarsi: a cadaver study.

The aim of this study was to analyse the pattern of sensory nerve endings and blood vessels around the sinus tarsi. The superficial and deep parts of the fat pads at the inferior extensor retinaculum (IER) as well as the subtalar joint capsule inside the sinus tarsi from 13 cadaver feet were dissected. The distribution of the sensory nerve endings and blood vessels were analysed in the resected specimens as the number per cm(2) after staining with haematoxylin-eosin, S100 protein, low-affinity neurotrophin receptor p75, and protein gene product 9.5 using the classification of Freeman and Wyke. Free nerve endings were the predominant sensory ending (P < 0.001). Ruffini and Golgi-like endings were rarely found and no Pacini corpuscles were seen. Significantly more free nerve endings (P < 0.001) and blood vessels (P = 0.01) were observed in the subtalar joint capsule than in the superficial part of the fat pad at the IER. The deep part of the fat pad at the IER had significantly more blood vessels than the superficial part of the fat pad at the IER (P = 0.012). Significantly more blood vessels than free nerve endings were seen in all three groups (P < 0.001). No significant differences in distribution were seen in terms of right or left side, except for free nerve endings in the superficial part of the fat pad at the IER (P = 0.003). A greater number of free nerve endings correlated with a greater number of blood vessels. The presence of sensory nerve endings between individual fat cells supports the hypothesis that the fat pad has a proprioceptive role monitoring changes and that it is a source of pain in sinus tarsi syndrome due to the abundance of free nerve endings.

[Structural reorganization of the main joint components during the experimental modeling of osteoarthrosis with reduced blood supply].

The reactive changes in the knee synovium, articular cartilage, and subchondral bone during osteoarthrosis modeling were studied in dogs (n = 5). The results of histomorphometry, scanning electron microscopy, and electron probe microanalysis have demonstrated that the osteoarthrosis model used (femoral artery ligation and the knee immobilization) lead to marked synovitis, axonal atrophy and nerve fiber degeneration in subsynovial nerves, as well as synovial membrane hypovascularization. Subchondral bone vascularization was shown to deteriorate, while calcium content was reduced. Destructive changes were detected in the articular cartilage. Chondrocytes of the intermediate zone which were equidistant from vascular and synovial sources of supply appeared to be the most vulnerable. The changes described are the consequences of the disturbed interactions of the main joint components indicating the reduction of synthesis with a predominance of catabolic processes.

The effect of neonatal gene therapy on skeletal manifestations in mucopolysaccharidosis VII dogs after a decade.

Mucopolysaccharidosis (MPS) VII is a lysosomal storage disease due to deficient activity of ß-glucuronidase (GUSB), and results in glycosaminoglycan accumulation. Skeletal manifestations include bone dysplasia, degenerative joint disease, and growth retardation. One gene therapy approach for MPS VII involves neonatal intravenous injection of a gamma retroviral vector expressing GUSB, which results in stable expression in liver and secretion of enzyme into blood at levels predicted to be similar or higher to enzyme replacement therapy. The goal of this study was to evaluate the long-term effect of neonatal gene therapy on skeletal manifestations in MPS VII dogs. Treated MPS VII dogs could walk throughout their lives, while untreated MPS VII dogs could not stand beyond 6 months and were dead by 2 years. Luxation of the coxofemoral joint and the patella, dysplasia of the acetabulum and supracondylar ridge, deep erosions of the distal femur, and synovial hyperplasia were reduced, and the quality of articular bone was improved in treated dogs at 6 to 11 years of age compared with untreated MPS VII dogs at 2 years or less. However, treated dogs continued to have osteophyte formation, cartilage abnormalities, and an abnormal gait. Enzyme activity was found near synovial blood vessels, and there was 2% as much GUSB activity in synovial fluid as in serum. We conclude that neonatal gene therapy reduces skeletal abnormalities in MPS VII dogs, but clinically-relevant abnormalities remain. Enzyme replacement therapy will probably have similar limitations long-term.

[Anatomic features of posterior septum of knee joint and its application in posterior trans-septal portal for arthroscopic surgery].

OBJECTIVE: To summarize the anatomic features of the posterior septum of the knee joint and its application in posterior trans-septal portal for arthroscopic surgery. METHODS: The literature related to posterior septum of the knee joint and arthroscopic surgery was extensively reviewed and analyzed. RESULTS: The posterior septum of the knee joint has more mechanoreceptors and blood vessels in the upper part, which are close to arteria popliteal at the tibial plateau level; the posterior compartment is divided into wider posteromedial and narrower posterolateral compartments. A safe arthroscopic trans-septal portal is established, in the knee flexion of 90 degrees, in a lateral-to-medial direction, and with an inserting location below the middle of posterior septum. CONCLUSION: The establishment method of posterior trans-septal portal is not uniform and all the features of posterior septum should be considered to decrease the complications.

Joint immobilization induced hypoxic and inflammatory conditions in rat knee joints.

The purpose of this study was to examine the hypoxic and inflammatory conditions after immobilization in the joint capsule of rat knees. The unilateral knee joints of adult male rats were immobilized with an internal fixator (Im group) for 1 day, 3 days, and 1, 2, 4, 8, and 16 weeks. Sham-operated animals had holes drilled in the femur and tibia and screws inserted without a plate (control group). The number of cells and blood vessels in the capsule were histologically examined. The hypoxic condition in the capsule was histologically examined with a Hypoxyprobe™-1. The gene expressions related to the hypoxic (hypoxia inducible factor-1α, vascular endothelial growth factor, and fibroblast growth factor 2) and inflammatory conditions [interleukin-6 (IL-6), IL-1α, IL-1ß, tumor necrosis factor-α, and tumor necrosis factor-ß] were evaluated by quantitative reverse transcription polymerase chain reaction. The number of cells was unchanged at 1 day in the two groups; however, the number significantly increased at 3 days in the Im group. The number of blood vessels in the Im group gradually decreased. Strong immunostaining of Hypoxyprobe™-1 around the blood vessels was observed in the Im group. The gene expressions of hypoxia inducible factor-1α and fibroblast growth factor 2 were significantly higher in the Im group compared with those in the control group. The gene expressions of IL-6, IL-1α, IL-1ß, and tumor necrosis factor-ß were significantly higher in the Im group compared with those in the control group. These data indicated that joint immobilization induced hypoxic and inflammatory conditions in the joint capsule, which might be an initiating factor for joint contracture.

Does hypoxia-reperfusion injury occur in osteoarthritis of the temporomandibular joint?

AIMS: To determine the available evidence in the literature for whether hypoxia-reperfusion injury plays a role in the pathogenesis of joint diseases in general and of osteoarthritis (OA) of the temporomandibular joint (TMJ) in particular. METHODS: The electronic databases CENTRAL, PubMed, and EMBASE were systematically searched. The search strategy combined thesaurus terms "reperfusion injury" and "joints" and excluded "tourniquet," which possibly induces iatrogenic reperfusion injury. Inclusion and exclusion criteria were applied, data were extracted, and quality was assessed. RESULTS: Four studies could be included, investigating four different aspects of the hypoxia-reperfusion mechanism in joints. All studies investigated several arthritides in the knee or shoulder joint and were observational studies, except for one section of one of the studies, which was a randomized controlled trial. These studies do not provide any evidence to support or reject the hypothesis that hypoxia reperfusion occurs in TMJ OA. Positive but weak evidence is provided to support the hypothesis that hypoxia-reperfusion injury occurs in OA of the knee joint. Furthermore, some results of the included studies suggest differences between OA and other types of arthritis in relation to the hypoxia-reperfusion mechanism. CONCLUSION: There is no evidence to support or reject the hypothesis that hypoxia reperfusion occurs in TMJ OA, and limited evidence is provided to support that hypoxia-reperfusion injury occurs in OA of the knee joint. Since the studies suggest differences between OA and other types of arthritis in relation to hypoxia-reperfusion mechanisms, further research in this field needs to distinguish OA from other types of arthritis.

The retinacula of Weitbrecht in the adult hip.

PURPOSE: The aim of the study was to describe the retinacula of Weitbrecht in the adult hip. MATERIALS AND METHODS: Specimens were obtained from 30 adult hips, average age was 77 years (age range 43-91 years), 8 specimens were fixed by formalin solution and 22 were not fixed. RESULTS: Anterior retinaculum was found in 40% of examined specimens. The anterior retinaculum was in 83% of cases formed by a flat plate and in 17% by two to three parallel bands. Medial retinaculum was present constantly, extending from the attachment of the articular capsule at the base of the lesser trochanter towards the fovea capitis femoris as far as the edge of the articular cartilage. Typically, the retinaculum had the form of an inverted "T". Of the three retinacula, the medial one was the strongest. Lateral retinaculum was also present constantly. In 89% of cases, it had the form of a quadrilateral plate adjacent to the upper surface of the femoral neck. This plate arises from the insertion of the articular capsule on the upper part of the femoral neck at the base of the greater trochanter close to the trochanteric fossa. The plate extended along the upper edge of the femoral neck as far as the edge of the articular cartilage. Microscopic examination revealed fine blood vessels running through the retinacula. CONCLUSION: Lateral retinaculum and medial retinaculum are constant synovial plicae in terms of both occurrence and localization. Nutritive arteries run through both the plicae to supply the femoral head.

Vascularization of the mandibular condylar head with respect to intracapsular fractures of mandible.

BACKGROUND: Causes of mandibular condylar (condylar) head necrosis as a consequence of intracapsular mandibular fractures are still a subject of controversy. OBJECTIVES: To investigate why in some cases of intracapsular fractures condylar head necrosis occurs. MATERIAL: 58 human heads from the collection of Head and Neck Clinical Anatomy Laboratory, from the Institute of Physiology and Pathology of Hearing, Warsaw, Poland, constituted the material. STUDY: Head arterial tree injections, anatomical preparation with the use of standard set of microsurgical equipment and an operating microscope. RESULTS: The main source of condylar head vascularization is the inferior alveolar artery, supplying bone marrow of the whole mandible as well as its cortical layer. Additional arterial blood supplying comes from a various number (2-7) of branches supplying the temporomandibular joint capsule. They originate directly from the maxillary artery or from its primary branches: masseteric artery, external pterygoid artery or superficial temporal artery. Two rare variants of accessory mandibular head vascularization were encountered. The first (2 cases) was an arterial branch from the maxillary artery and the second (1 case) was a branch from the external pterygoid artery. In these cases the arterial supply of lateral part of temporomandibular joint capsule from other sources was reduced. CONCLUSION: Fractures resulting in the lateral part of the condylar head in isolation could be potentially threatened by necrosis because of poor vascularization.

An anatomic study of the posterior septum of the knee.

PURPOSE: To evaluate the posterior septum of the knee and determine the presence of a safe zone that could be removed, without significant damage to blood vessels and nerves. METHODS: Nineteen fresh unpaired adult human cadaveric knees, with no macroscopic degenerative or traumatic changes, were used in this study. Microscopic evaluation was performed by analysis of H&E, CD-34, and S-100 staining. RESULTS: The posterior septum of the knee is rich in type II and type IV mechanoreceptors and blood vessels. The superior half has a greater number of blood vessels (21.52 ± 6.36 v 12.05 ± 4.1, P < .001), higher-caliber vessels (2.2 ± 0.89 µm v 1.41 ± 0.45 µm, P < .006), and a greater number of mechanoreceptors per field (type II, 1.8 ± 1.8 v 0.42 ± 1, P = .04; type IV, 22.6 ± 14 v 14.5 ± 9.4, P = .04) than the inferior half of the septum. CONCLUSIONS: This study has shown that the posterior septum of the knee is highly vascularized and has a great number of type II and IV mechanoreceptors. The presence of these structures is significantly higher in the superior half of the septum. CLINICAL RELEVANCE: If debridement of the posterior septum is necessary, it should be done at the inferior aspect so that a greater number of blood vessels and mechanoreceptors can be preserved.

Capsular and pericapsular contributions to acetabular and femoral head perfusion.

BACKGROUND: Capsular and pericapsular vessels are believed to contribute to acetabular and femoral head perfusion, but, to our knowledge, there is no anatomic study to support this theory. The purpose of this study was to describe the vascular anatomy of the hip with particular reference to the contributions of the capsular and pericapsular vessels. METHODS: Twenty fresh cadavers were dissected twenty-four hours after intra-arterial injection of colored silicone. The arteries supplying the hip were followed by careful dissection from their origins outside the pelvis to their terminal branches. Particular attention was paid to the vessels traveling between the acetabulum and the capsule and the femoral head. RESULTS: In all twenty specimens, the hip capsule received blood supply from the superior and inferior gluteal arteries proximally and from the medial and lateral femoral circumflex arteries distally. The contributory vessels entered the capsule peripherally and superficially. The circumflex arteries supplied the anterior capsule. The gluteal arteries supplied the posterior and posterosuperior aspect of the hip capsule, augmented by contributions from the circumflex arteries. Variable anastomoses were found between the gluteal and femoral systems on the capsular surface beneath the gluteus minimus and short hip external rotators. The medial femoral circumflex artery provided the dominant blood supply to the femoral head in eighteen specimens, and the inferior gluteal artery provided the dominant supply in two specimens. CONCLUSIONS: Capsular and pericapsular vessels that contribute to the blood supply of the acetabulum run on the posterior and posterolateral surface of the capsule. The dominant blood supply to the femoral head comes from vessels that approach the joint posteriorly and penetrate the joint near the femoral attachment of the capsule.

Integrity of posterior retinaculum after displaced femoral neck fractures.

INTRODUCTION: It is widely thought that the posterior retinaculum is intact only in relatively undisplaced intracapsular fractures, and interruption of the arterial flow through the retinacular arteries to the femoral head is the main cause of avascular necrosis after fracture of the neck. PATIENTS: In order to test the hypothesis that the posterior retinaculum is torn after a displaced femoral neck fracture, 112 patients (45 males and 67 females), 75 years old on average, underwent a hemiarthroplasty for a displaced femoral neck fracture. There were 71 Garden type III and 41 Garden type IV fractures. The integrity of the posterior retinaculum was examined intraoperatively in every patient during the procedure. RESULTS: The posterior retinaculum was found intact in all of the Garden type III fractures and in 39 Garden type IV fractures. The posterior retinaculum was found torn in two Garden type IV fractures. There was no tearing in any other part of the capsule of the hip joint in any patient. CONCLUSIONS: The posterior retinaculum of the hip joint remains intact after a displaced femoral neck fracture in all of Garden type III fractures and in the great majority of Garden type IV fractures.

The posterior segment of the temporomandibular joint capsule and its anatomic relationship.

PURPOSE: The aim of this work was to clarify the arrangement of the posterior segment of the temporomandibular joint capsule and its pertinent relationships. MATERIALS AND METHODS: The temporomandibular region was dissected bilaterally in 20 adult cadavers. Natural stained latex was injected into 16 cadavers through the external carotid artery to facilitate the dissection of the arterial vessels. RESULTS: The posterior segment of the joint capsule is made up of the so-called "bilaminar zone" of the articular disc. The upper internal portion of the posterior segment of the capsule was reinforced by the discomalleolar ligament. The retroarticular space was filled with loose connective tissue and the anterior branches of the anterior tympanic artery were distributed throughout the posterior segment of the joint capsule. CONCLUSION: The posterior segment of the temporomandibular joint capsule corresponds to the bilaminar zone of the articular disc. The structures of the retroarticular space are extracapsular.

Endoscopic laser imaging of tissue perfusion: new instrumentation and technique.

BACKGROUND AND OBJECTIVES: New instrumentation, based on a previously established laser speckle perfusion imaging (LSI) technique is evaluated for its ability to capture and generate blood flow images during endoscopic surgery. STUDY DESIGN/MATERIALS AND METHODS: Investigations are detailed in an in-vitro blood flow model simulating physiological properties of vascularized tissue, and in-vivo in rabbit joint capsule tissue. RESULTS: In-vitro measurements showed a linear response of the instrument to blood flow in the range of 0-800 microl/minute, where data points were significantly correlated with an r(2) value of 0.96. In-vivo measurements showed a 58.7% decrease to the medial collateral ligament during occlusion of the femoral artery. CONCLUSIONS: Blood flow images demonstrate that the endoscopic LSI technique is capable of measuring relative tissue blood flow changes at high resolutions and rapid response times and incorporates well with endoscopic surgeries.

The vascular anatomy of the glenohumeral capsule and ligaments: an anatomic study.

BACKGROUND: A detailed description of the vascular anatomy of the shoulder capsule is lacking, yet surgical procedures may put this capsular blood supply at risk. We hypothesized that a hypovascular area is present in the capsule. The purpose of the present study was to describe the vascular anatomy of the human glenohumeral capsule and ligaments and its relevance to surgical treatment of the shoulder. METHODS: In twenty-four fresh adult cadaveric shoulders, the axillary artery proximal to the thoracoacromial branch and the suprascapular artery were injected with India ink. The specimens were sectioned and then cleared with a modified Spalteholz technique. RESULTS: The glenohumeral capsule demonstrates consistent arterial contributions from the anterior circumflex, posterior circumflex, circumflex scapular, and suprascapular arteries. The arterial supply is centripetal in nature. The contributing vessels enter the capsule both laterally and medially and arborize toward the middle of the capsule. The rotator cuff provides additional blood supply to the capsule through perforating vessels. The dominant capsular vessels run horizontally and form intracapsular anastomoses via vertical branches. The anterior and posterior bands of the inferior glenohumeral ligament complex are vascularized by adjacent parallel vessels. In five of twelve specimens, a hypovascular zone was located near the humeral insertion of the anterior aspect of the capsule. In these five specimens, there was an associated hypovascular zone in the underlying capsule. CONCLUSION: The glenohumeral capsule is a well-vascularized structure with direct predictable contributions from four named arteries. These arteries send branches that enter the capsule superficially and from the periphery. These dominant vessels run horizontally toward the midcapsule and to deeper layers of the capsule. Vessels originating from the rotator cuff provide additional blood supply to the capsule.

Abrogation of alpha-adrenergic vasoactivity in chronically inflamed rat knee joints.

It has previously been shown that chronic inflammation causes a reduction in sympathetic nerve-mediated vasoconstriction in rat knees. To determine whether this phenomenon is due to an alteration in smooth muscle adrenoceptor function, the present study compared the alpha-adrenoceptor profile of blood vessels supplying the anteromedial capsule of normal and chronically inflamed rat knee joints. While the rats were under urethan anesthesia, the alpha(1)-adrenoceptor agonists methoxamine and phenylephrine and the alpha(2)-adrenoceptor agonist clonidine (0.1-ml bolus; dose range 10(-12)-10(-7) mol) were applied to exposed normal rat knees, resulting in a dose-dependent fall in capsular perfusion. Comparison of drug potencies indicated that alpha(2)-adrenergic effects > alpha(1)-vasoactivity. One week after intra-articular injection of Freund's complete adjuvant to induce chronic joint inflammation, the vasoconstrictor effects of methoxamine, phenylephrine, and clonidine were all significantly attenuated compared with normal controls. These findings show that the preponderance of sympathetic adrenergic vasoconstriction in the anteromedial capsule of the rat is carried out by postjunctional alpha(2)-adrenoceptors. Chronic joint inflammation compromises alpha(1)- and alpha(2)-adrenoceptor function, and this change in alpha-adrenergic responsiveness may help explain the perfusion changes commonly associated with inflammatory arthritis.

The course of blood vessels in the hip joint capsule of the dog.

The course and the arrangement of capsular blood vessels in the joint capsule's wall, together with their extracapsular origins, were investigated using cleared specimens that had been injected with Latex, or Technovit, or India-ink in serum. Arteries enter areas of the joint capsule's wall near its femoral as well as coxal attachment. The intramural vascular network is arranged in layers which are assigned to the stratum fibrosum and stratum synoviale, with one or two intermediate, less distinct layers in between. The ramification in the network of the stratum fibrosum is mainly stellate. Circular anastomoses connecting the supplied areas are located in the capsule's periphery. In the stratum synoviale, the vascular network is made of close, elongated meshes in a circular extension.