The use of intravenous gadopentetate dimeglumine in magnetic resonance imaging of synovial lesions

Spin echo T1- and T2-weighted images and intravenously administered gadopentetate dimeglumine-enhanced T1-weighted images were obtained in 4 normal volunteers and 11 patients (11 joints) with painful, intermittent, or persistent joint swelling of unknown etiology. These studies were retrospectively reviewed to assess the benefits of contrast-enhanced magnetic resonance imaging (MRI) in evaluating the synovium. Normal synovium and joint fluid showed no visually apparent enhancement on images obtained immediately after intravenous injection of gadopentetate dimeglumine. Abnormal synovium enhanced significantly, allowing the precise identification of equivocal or unsuspected synovial disease processes. These results suggest that, in selected cases, enhanced MRI can be a useful adjunct in the evaluation of suspected synovial disease processes.

Full-thickness tears of the rotator cuff of the shoulder: diagnosis with MR imaging

The purpose of this study was to describe MR findings in full-thickness tears of the rotator cuff. Of 102 shoulders examined by MR imaging, 31 were found to have a full-thickness tendon tear at arthroscopy/bursoscopy (five shoulders) or open surgery (26 shoulders). All shoulders were imaged in oblique coronal and axial planes. MR images of the 102 shoulders were evaluated for (1) the presence of fluid in the subacromial and subdeltoid bursae; (2) abnormal signal of the supraspinatus, subscapularis, infraspinatus, and teres minor tendons; (3) interruption of tendon continuity and thinning of the tendon; and (4) proximal retraction of the junction of the muscle and tendon. The presence or absence of each finding was determined by consensus of two radiologists, who interpreted the images without knowledge of the surgical findings. Results in those 31 shoulders with proved full-thickness tears were: fluid in the subacromial bursae (29 shoulders), interruption of tendinous continuity (22 shoulders), focally increased signal of the tendon equivalent to that of water (27 shoulders), and musculotendinous retraction (24 shoulders). The finding of subacromial fluid was a sensitive indicator (93%) of a full-thickness tear, and interruption of tendinous continuity was a specific finding (96%) in diagnosing a full-thickness tear. Our experience shows interruption of tendon continuity is the most specific MR finding of full-thickness rotator cuff tears, while subacromial fluid is the most common finding.

MR imaging of joints: analytic optimization of GRE techniques at 1.5 T

To clarify the choice of imaging parameters for optimal gradient-recalled echo MR scanning of joints, we analyzed the behavior of contrast-to-noise and signal-to-noise ratios for spoiled (i.e., fast low-angle shot [FLASH] or spoiled GRASS) and steady-state (i.e., gradient-recalled acquisition in the steady state [GRASS] or fast imaging with steady precession) techniques at 1.5 T. The analysis is based on tissue characteristics derived from spin-echo measurements of hyaline cartilage and synovial fluid signal in the patellofemoral joints of 11 volunteers. Separate analysis of contrast-to-noise and signal-to-noise ratios for multiplanar (long TR) acquisitions shows that these parameters are each improved compared with single-slice methods. At TRs greater than 250 msec, there is no significant difference in the contrast behavior of FLASH and GRASS. For optimal contrast-to-noise ratio (synovial fluid-cartilage), the best multiplanar sequence (for TE less than 23 msec) is with a short TE and a large flip angle (e.g., 400/9/73 degrees [TR/TE/flip angle]). If a single-scan or three-dimensional technique is desired, than a GRASS sequence at minimal TR and TE and intermediate flip angle (18/9/32 degrees) is best. For optimal signal-to-noise ratio (for both synovial fluid and hyaline cartilage), the best multiplanar sequence uses a short TE and an intermediate flip angle (e.g., 400/9/30 degrees). If a short TR, high signal-to-noise technique is desired, then GRASS (18/9/13 degrees) is superior to FLASH.

Holmium-laser synovectomy of immune synovitis in rabbits

Holmium-laser synovectomy was carried out to remove allergically inflamed synovial membranes in rabbit knee joints. The healing process was then investigated at different periods. Left knee joints of 12 rabbits were exposed to Ho:YAG-laser radiation at a wavelength of 2.1 microns, pulse energy of 600 mJ, pulse length of 1 ms, and repetition rate of 3 Hz. Twelve others were treated conventionally and 12 served as controls. After 1 day, 1 week, and 1 and 3 months, respectively, 3 animals from each group were sacrificed and the synovialis grossly and microscopically examined. Coagulation necrosis, inflammation, and edema resulted following laser therapy. After 1 week, the synovial layer consisted of a scarlike formation of fibers and within 1 month, its surface appeared smooth. The mechanical abrasion caused hemorrhage and necrosis. Fibrosis developed in the capsular layers, and after 3 months, the surface appeared coarse and villous. Based on these preliminary findings, holmium-laser synovectomy may offer an alternative method to existing therapeutic techniques.

MR imaging in hemophilic arthropathy

20 children with hemophilia were examined with Magnetic Resonance Imaging (MRI) to determine if MRI could be used to assess hemophilic arthropathy, especially in the early stages. 28 joints of the appendicular skeleton were imaged, including 17 knees, 10 ankles and 1 elbow. The results were compared to clinical and plain radiographic assessments and to the surgical findings when synovectomy was performed. MRI is able to evaluate the components of hemophilic arthropathy such as fluid effussion, synovial hypertrophy, the status of the articular cartilage, and bony lesions. These lesions can be discovered at an early stage when plain radiographs are still normal. MRI seems to be useful for the selection of patients needing early treatment of hemophilic arthropathy and in monitoring response to therapy.

Synovial fistula of the knee: a complication of arthroscopy

The occurrence of a synovial fistula after knee arthroscopy is uncommon. In a retrospective review of 976 arthroscopies of the knee over 3 years, six patients developed synovial fistulae (incidence 6.1/1,000). All patients were treated with short-term immobilization and oral prophylactic antibiotics. All fistulae closed after an average of 9 days of immobilization, and none required further treatment. Risk factors that may predispose a patient to fistula formation are posterior compartment portals and the presence of significant degenerative joint disease. A treatment protocol is presented.

Matrix engineering

Matrix engineering is a technology that utilizes hyaluronan (HA, hyaluronic acid) based matrices to control, direct or augment tissue regenerative processes. Hyaluronan and the concept of matrix engineering have become established tools in ophthalmic and orthopaedic medicine. The clinical indications for HA are limited by the physical properties and short residence time of the natural HA molecule. To expand and improve upon its current medical applications, a family of HA derivatives was prepared by chemical modification and cross-linking. Relative to the non-modified HA molecule, the hylan family of polymers provides more versatile physical forms, improved mechanical properties and an extended residence time. Hylan can also be used as a surface coating to improve blood compatibility. The chemical, physical and biological properties of hylans will be reviewed, focusing on the specific therapeutic indications they enable.

Synovial fluid does not inhibit collagen synthesis. Bovine cruciate ligament studied in vitro

An organ culture model of four bovine anterior cruciate ligaments was used to compare synovial fluid with bovine serum, lactated Ringer's solution, and Basal Medium Eagle's (BME) to determine their relative abilities to support in vitro conversion of proline into hydroxyproline. There was no difference between serum and synovial fluid in their ability to support collagen synthesis. These results suggest that bovine synovial fluid is not inhibitory in that it is similar to bovine serum in supporting ligament collagen synthesis under the conditions described.

Development and evaluation of a method for preservation of synovial fluid wet preparations for quality control testing of crystal identification

We describe a technique for embedding drops of fresh synovial fluid in mounting resin to prepare test slides that retain crystal morphology for at least 2 weeks. Hospital and private rheumatologists were solicited nationwide to test themselves and their staff with 5 unknown specimens. Eighty-nine percent identified monosodium urate (MSU) crystals from a tophus but only 71% identified smaller and less frequent MSU. Seventy-five percent correctly identified calcium pyrophosphate dehydrate and 42% detected steroid crystals. Apatite crystal clumps included as control slides with no birefringent material were suspected by only 7%. This or another method which simulates actual practice by also testing the equipment and handling of the microscope is proposed as an important component of quality control testing programs for synovianalysis.

[Microstructure of tendon and its clinical significance]

Superficial and internal-structure of human and rat tendons were investigated under scanning electronic microscopy. Histologically, there are many pores on the synovium, under which a layer of network of fiber bands wraps the tendon. The synovial fluid propulsion system includes: Synovium----pores----network of fiber bands----space of tendon bands----space of tendon fibers. The synovial fluid is propelled through the above structure. The function of the network structure is like a sponge, it has the function of nutrition, absorption of heat, and lubrication.

Case report 630: Reactive bursa formation surrounding an osteochondroma

In summary, chondrosarcoma arising in an osteochondroma is a difficult diagnosis to establish on radiological-morphological grounds, especially in low grade lesions. A patient with a painful, enlarging exostosis usually comes to require resection even in the absence of radiographic hallmarks of malignancy. Although many osteochondromas complicated by bursal formation will be resected for relief of symptoms, the identification of a reactive bursa surrounding an exostosis without grossly malignant features presages a benign course and will dramatically effect established preoperative plans.

Two lymphoscintigraphic agents compared in vitro and in vivo in rabbit knees

Two 99mTc-labelled colloidal radiopharmaceuticals [99mTc-albumin colloid (A) and 99mTc-rhenium sulfide colloid (B)] were compared in vitro in saline, plasma, and synovial fluid with regard to particle size, radiochemical purity, protein binding level, and stability at varying acidity. The purpose was to compare the two compounds in studies of lymphatic drainage from the knee joint of rabbits. Particle size for A was uniform at about 10 nm, but for B it varied between 40 and 80 nm. The radiochemical purity was lowest for B (90%-95%), with a small fraction of minor particles. B was protein bound, which was only the case for A in joint fluid from synovitic knees. A faster disappearance of A than B was observed from the knee joint, with lesser retention in the regional lymph nodes. A negligible uptake of colloid was seen in the liver. The major fraction of radioactivity absorbed from the knee was excreted in the urine. The differences between in vitro and in vivo stability are probably due to phagocytosis in the synovial membrane.

Gadolinium-DTPA in rheumatoid arthritis and related diseases: first results with dynamic magnetic resonance imaging

Thirty-four joints (19 knees, 15 wrists) of 31 patients suffering from rheumatoid arthritis and related disorders were examined prior to and following intravenous administration of Gadolinium-DTPA (0.1 mmol/kg body weight). T1-weighted spin-echo sequences and the gradient-echo technique FLASH were applied. FLASH scanning was used for the registration of the time-dependent changes of signal intensity following Gd-DTPA. Synovial proliferations exhibited a rapid and marked increase of signal intensity whereas fatty tissue, bone marrow, muscle and synovial effusion demonstrated only minor changes, causing enhanced contrast between synovial pannus and joint effusion or other neighbouring structures. Within the synovial pannus, ratios (absolute signal increase) of 131.3 +/- 53.4% and 122.9 +/- 51.1% were found in T1-weighted spin-echo and in FLASH sequences respectively. The average signal increase gradient of pannus (108.2 +/- 70.6%/min) was significantly (p less than 0.001) different from muscle (13.4 +/- 7.8%/min), fatty tissue (10.2 +/- 8.4%/min), bone marrow (5.5 +/- 7.1%/min), and joint effusion (14.7 +/- 7.8%/min).

Localisation of lysozyme mRNA in rheumatoid synovial membrane by in situ hybridisation

Type A synovial lining cells have been shown to contain lysozyme in their lysosomes. This might be phagocytosed because synovial fluid contains lysozyme originating from tissue macrophages and articular cartilage but in arthritides, in particular, from neutrophils. In situ hybridisation with 35S labelled cDNA was used to detect mRNA for lysozyme over synovial lining in patients with rheumatoid arthritis. No hybridisation was found with lactoferrin cDNA, which was used as a negative control. Computer search against the EMBL gene bank (release 14) did not show any significant cross hybridisation to a known sequence. In cytological specimens 35S-cDNA:mRNA hybrids were observed in positive but not in negative control cells. The presence of lysozyme and its mRNA suggests that type A synovial lining cells are of mononuclear phagocyte lineage.

Mechanisms of disc displacement in the temporomandibular joint

The sign of 'clicking' in the temporomandibular joint is not a normal phenomenon. It is, in fact, often the first indication of potential myofascial pain or temporomandibular joint pain dysfunction syndrome and as such should be detected early and diagnosed correctly. Clicking is a cardinal sign of altered function within the joint, the aetiology for which can only be diagnosed from a sound knowledge of anatomy and physiology. With this background it is possible to ascertain whether the cause is essentially biochemical, neuromuscular, or occlusal in nature or multifactorial components of all three categories. An attempt has been made to provide background knowledge in order that a correct diagnosis can be made.

Quantification of knee joint fluid volume by MR imaging and CT using three-dimensional data processing

A noninvasive, quantitative technique to estimate joint fluid volume using three-dimensional (3D) processing of magnetic resonance (MR) imaging and CT data was evaluated. The mean accuracy error of this 3D approach with MR imaging, performed on five fresh cadaver knees, was -2.4 +/- 5.1% SD when volume estimates were based on heavily T2-weighted transverse images. A considerably higher mean accuracy error of -12.5 +/- 16.9% SD was found when the 3D approach with CT was used (four fresh cadaver knees), probably because of the small attenuation differences between articular soft-tissue structures and joint fluid. A mean precision error of 4.9 +/- 2.3% SD was found when two radiologists independently evaluated in vivo MR imaging studies of 12 knees with joint effusion. Because of the low CT accuracy, no in vivo studies were performed using CT. Thus, this preliminary study shows that quantification of joint fluid volume with 3D data processing offers more accuracy with MR imaging than with CT. The 3D approach with MR imaging provides a potential tool for clinical studies.

Synovial fluid osmolality in osteoarthritis and rheumatoid arthritis

The osmolality of synovial fluid aspirated from the knees of 15 rheumatoid and 15 osteoarthritic patients was observed concurrently with the same measurement on blood serum. The group averages were compared to a group of 13 with identical apparati. Synovial fluid osmolality in rheumatoid arthritics (280 +/- 7.7 mmol/kg) was significantly different from that in osteoarthritics (297 +/- 16.9 mmol/kg), and both group averages were significantly different from normal (404 +/- 57 mmol/kg). Blood serum osmolality also differed between the normal and the two arthritic groups. The potential application of vapor pressure osmometry techniques in the diagnosis and management of joint disease is discussed.

Inflammatory synovial fluid and absorbable suture strength

The effect of inflammatory synovial fluid upon several absorbable sutures commonly used for meniscus repair was studied by implanting lengths of these sutures into unstable, arthritic rabbit knees and, after varying lengths of time (1-6 weeks), testing their breaking strength. Both polyglactin-910 (Vicryl) and polyglycolic-acid (Dexon) sutures retained only minimal breaking strength 3 weeks after implantation. Chromic gut sutures demonstrated a steady reduction in breaking strength until they retained only 6% of their original strength at 5 weeks and none at 6 weeks. Polydioxanone (PDS) sutures began to lose breaking strength at 2 weeks and retained only 40% of their original strength 5 weeks after implantation. The rate of loss in polydioxanone breaking strength was faster in inflammatory synovial fluid than previously reported in the normal synovial joint. Braided polyester sutures (Mersiline) showed no loss of breaking strength over the duration of this test. While the choice of suture is only one variable influencing the outcome of a meniscus repair, this study demonstrates that only polydioxanone and green braided polyester sutures retain any strength 6 weeks after implantation (the time of immobilization commonly recommended for meniscal repairs). Complete meniscal healing can require several months. In the absence of compelling evidence to the contrary, the use of nonabsorbable suture materials for meniscal repair seems the most appropriate choice.

The effect of grinding conditions on the toxicity of cobalt-chrome-molybdenum particles in vitro

Powders of cobalt-chrome-molybdenum alloy were produced by grinding larger particles for 8 h in water, serum or joint fluid. They were administered, in low doses (0.05-0.5 mg/ml) for 1-6 d, to human dermal fibroblasts in vitro. Particles were ground in a biological fluid in order to simulate conditions in an artificial hip joint. Such particles adhered to, or were phagocytosed by, the cells far less than those ground in water. The toxicity of the alloy was linked with a failure of test cells to grow as quickly as the controls - particles ground in water were the most toxic.