Experimental osteoarthritis: a survey

Design and Fabrication of Micro Saw Enabling Root-Side Cutting of Bone

A novel micro saw was fabricated using a combination of photolithography and electroplating techniques, resembling a miniature timing belt with sideways blades. The rotation or oscillation direction of the micro saw is designed to be perpendicular to the cutting direction so that transverse cutting of the bone is attainable to extract a preoperatively planned bone-cartilage donor for osteochondral auto-graft transplantation. The mechanical property of the fabricated micro saw obtained using the nanoindentation test shows that the mechanical properties of the micro saw are almost an order of magnitude higher than bone, which indicates its potential bone-cutting application. To demonstrate the cutting capability of the fabricated micro saw, an in vitro animal bone cutting was performed using a custom test rig consisting of a microcontroller, 3D printer, and other readily available parts.

Recent advance in treatment of osteoarthritis by bioactive components from herbal medicine

Osteoarthritis (OA) is a common chronic articular degenerative disease, and characterized by articular cartilage degradation, synovial inflammation/immunity, and subchondral bone lesion, etc. The disease affects 2-6% of the population around the world, and its prevalence rises with age and exceeds 40% in people over 70. Recently, increasing interest has been devoted to the treatment or prevention of OA by herbal medicines. In this paper, the herbal compounds with anti-OA activities were reviewed, and the cheminformatics tools were used to predict their drug-likeness properties and pharmacokinetic parameters. A total of 43 herbal compounds were analyzed, which mainly target the damaged joints (e.g. cartilage, subchondral bone, and synovium, etc.) and circulatory system to improve the pathogenesis of OA. Through cheminformatics analysis, over half of these compounds have good drug-likeness properties, and the pharmacokinetic behavior of these components still needs to be further optimized, which is conducive to the enhancement in their drug-likeness properties. Most of the compounds can be an alternative and valuable source for anti-OA drug discovery, which may be worthy of further investigation and development.

Intra-articular hyaluronate in experimental rabbit osteoarthritis can prevent changes in cartilage proteoglycan content

OBJECTIVE

The purpose of this study was to determine the effects of intra-articular injections of high molecular weight (2000 kDa) sodium hyaluronate (HA) on the progression of articular cartilage degeneration in a rabbit partial medial meniscectomy model of osteoarthritis.

DESIGN

Six experimental groups included normal, sham operated, and operated and injected animals, the latter injected once-weekly (for two weeks or twelve weeks, beginning four weeks after surgery) with either 1% (w/v) HA or phosphate buffered saline (PBS). Following assessment of gross morphology, serial adjacent blocks of full-depth articular cartilage were prepared from the tibial condyle for analysis of total water, hydroxyproline, DNA and proteoglycan (uronic acid) content, as well as the ratio of galactosamine to glucosamine. Samples were sub-divided into inner (medial) and outer (lateral) regions.

RESULTS

No morphological differences were recognized between joints injected with PBS and those receiving HA. When analysed biochemically, there were no significant differences in hydration, hydroxyproline or DNA content between the experimental groups. In contrast, HA injection did affect changes in proteoglycan content. Expressed per tissue dry weight, uronic acid content in the operated group injected with PBS for two weeks was lower than normal (P<0.02), a result not seen in the corresponding HA injected group. After 12 weeks of PBS injections, uronic acid content (per dry weight) was higher than normal (P<0.01), an effect again not observed in the corresponding HA injected group. Results for the galactosamine: glucosamine ratio showed a reduction after 12 weeks of injections, but no differences between PBS and HA injected groups.

CONCLUSIONS

Once-weekly, intra-articular injection of high molecular weight HA can prevent changes in proteoglycan content in tibial condylar articular cartilage, compared to PBS injected controls, in the rabbit partial meniscectomy model of osteoarthritis.

Expression of interleukin-6 in osteoarthritic chondrocytes and effects of fluid-induced shear on this expression in normal human chondrocytes in vitro

This study tested the effect of fluid-induced shear on interleukin-6 expression in normal human articular chondrocytes in vitro. As determined by Northern blot analysis, interleukin-6 mRNA expression occurs in chondrocytes from osteoarthritic cartilage but not in normal chondrocytes. Applying fluid-induced shear stress to primary high density cultures of chondrocytes increased interleukin-6 mRNA signal 4-fold at 1 hour and 10 to 15-fold at 48 hours compared with unsheared control cultures. At 48 hours, fluid-induced shear stress increased interleukin-6 protein levels in the culture medium 9 to 10-fold compared with unsheared controls. mRNA signals for interleukin-1alpha, interleukin-1beta, and tumor necrosis factor-alpha in RNA from sheared or control chondrocytes were not detected by Northern blotting. Transforming growth factor-beta mRNA signal was detectable but was not affected by shear. In contrast, human lung fibroblasts (WI-38) responded to fluid-induced shear with increased signal for transforming growth factor-beta, but not interleukin-6, mRNA. Both cell types did respond to interleukin-1alpha with increased interleukin-6 mRNA signal. These data demonstrated that distortional forces, such as fluid-induced shear stress, alter interleukin-6 levels in normal chondrocytes in vitro and suggest that increased interleukin-6 expression in osteoarthritic cartilage may result, in part, from alterations in the mechanical loading of the tissue.

Intraarticular abnormalities in association with posterior cruciate ligament injuries

The effect of an isolated injury of the posterior cruciate ligament on the articular cartilage and menisci has not been extensively studied. Intraarticular abnormalities in 88 arthroscopically proven posterior cruciate ligament tears in symptomatic patients with straight unidirectional posterior instability were reviewed. There were 33 patients with acute injuries (range, 3 to 21 days; mean, 14) and 55 patients with chronic tears (range, 28 to 3650 days; mean, 786). Of the acute injuries, chondral defects occurred in 4 patients (12%) and meniscal tears in 9 patients (27%; 6 lateral and 3 medial). Chondral defects of both the lateral femoral condyles and patella were present in all 4 patients. Of the chronic injuries, chondral defects occurred in 27 (49%) and meniscal tears in 20 patients (36%) (7 lateral and 17 medial). Chondral defects of the medial femoral condyle were most common. The mechanism of injury resulting in an isolated injury of the posterior cruciate ligament is most likely to affect the lateral compartment or the articular cartilage of the patella. The incidence of articular defects and the incidence of meniscal tears increased in patients with chronic posterior cruciate ligament injuries; both lesions increased most in the medial compartment.

Diagnosis of an ACL disruption with KT-1000 arthrometer measurements

The KT-1000 was used to measure anterior tibial displacement in three populations: normal subjects (n = 120), patients with unilateral acute anterior cruciate ligament (ACL) disruptions (n = 105), and patients with chronic unilateral ACL disruptions who were scheduled for ACL reconstructions (n = 159). All patients with ACL disruptions were measured with and without anesthesia. Tibial displacement under three loading conditions was measured: 89-N anterior displacement force, manual maximum displacement force, and quadriceps contraction to lift the leg. The measurements of the normal knee in the injured populations were not significantly different from those of the knees in the normal population on any test. The injured knee tested with and without anesthesia was significantly different from the normal knee on all tests. The right-left difference in the normal population as less than 3 mm in 98% of patients in the 89-N test, 97% in the manual maximum test, and 99% in the quadriceps active test. The largest amount of displacement and the greatest difference in displacement between the injured and the normal knee was produced by the manual maximum test. The manual maximum injured-minus-normal knee displacement was 3 mm or more in 99% of patients with chronic ACL disruptions and in 95% of patients with acute ACL disruptions.

Rabbit knee immobilization: bone remodeling precedes cartilage degradation

This study analyzed processes underlying osteoporosis and osteoarthrosis after short-term immobilization of the right hind limb of postadolescent (2.8 kg) and mature (4.0 kg) rabbits. After 3 weeks, the lateral posterior aspect of the lateral tibial plateau and the lateral femoral condyle of the immobilized limb exhibited prominent subchondral vascular eruptions. Femoral metaphyseal bone density decreased 27 and 18% in the immobilized limbs of postadolescent and mature rabbits, respectively. Calcein green fluorescence increased 1.9-fold (p less than 0.001) in the metaphyseal trabeculae of immobilized femurs. With immobilization, sulfate incorporation into femoral cartilage glycosaminoglycan increased, although total cartilage glycosaminoglycan and hydroxyproline levels were unchanged. Thymidine incorporation into DNA increased four- to fivefold in tibial and femoral cartilage of the immobilized limb. In this study, bone loss and remodeling preceded erosive cartilage degradation.

Posttraumatic anterior cruciate ligament insufficiency as a cause of osteoarthritis in a knee joint

The purpose of the present investigation was to examine and describe the osteoarthritic changes that chronic, partial or complete anterior cruciate ligament (ACL) insufficiency causes to the knee joint. The most characteristic findings in 77 patients with average follow-up of eight years were osteophytes and subchondral sclerosis of femoral and tibial medial condyles, tibial eminence and patella, as well as narrowing of medial or lateral joint space. Only five patients (14%) in the group with partial, but 28 (70%) of those with complete insufficiency of the ACL suffered from a clear posttraumatic osteoarthritis of the injured knee. In complete tears, the total extent of these pathological changes per patient was fourfold compared to the patients with partial tear. It was concluded that chronic, posttraumatic insufficiency of the ACL causes characteristic osteoarthritic changes to the injured knee and that the amount of these changes seems to depend on the amount of the insufficiency. Therefore, a quick restoration of the static and dynamic stability of the injured knee must be the privilege of every knee injury patient in order to prevent the development of premature osteoarthritis.

Four to ten year followup of unreconstructed anterior cruciate ligament tears

Both operative and nonoperative methods have been advocated for the treatment of ACL tears. However, the optimum management of this injury remains controversial. In the present study, patients treated nonoperatively were evaluated retrospectively 4 to 10 years after ACL tears were documented by arthroscopy and by mild to moderate pivot shifts under anesthesia. Forty-nine patients who underwent arthroscopic evaluation of the knee between 1976 and 1982 were found to have complete tears of the ACL. A mild to moderate pivot shift was present under anesthesia. One or both menisci were torn in two-thirds of the knees, requiring partial meniscectomies. The average age of the patients was 27 years (range, 16 to 46 years). Because of persistent disabling instability, 9 patients (18%) underwent late ACL reconstruction. The remaining 40 patients were evaluated at an average of 5.6 years after documentation of the tear (range, 4 to 10 years). At followup, 25 (62%) of the 40 patients had satisfactory subjective results. Eight of the patients (20%) had returned to their preinjury level of athletic activities without restrictions, and 10 (25%) functioned at the same level but with symptoms, some patients requiring bracing. Seventeen patients (43%) had diminished their level of sports activities, while 5 patients (12%) had given up all sports. Only 2 patients required late meniscectomies. On physical examination, 27 patients (87%) had pivot shifts. Instrumented laxity testing revealed an injured to normal difference of 3.1 mm with a 20 pound force. Radiographic studies were interpreted as normal in 35% of the knees, whereas 65% demonstrated mild degenerative changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Synovitis causes hypoxia and acidity in synovial fluid and subchondral bone

The purpose of the present study was to evaluate the environmental changes in synovial fluid and subchondral bone during synovitis in rabbits in which the knee joint on one side was subjected to a procedure causing instability; a traumatic synovitis rapidly developed. Three weeks following the procedure, partial pressure of oxygen (PO2), partial pressure of carbon dioxide (PCO2) and hydrogen ion concentration (pH) were measured in vivo in the juxta-articular bone and in the synovial fluid of both the normal and the affected sides. Mass spectrometry was used for simultaneous registration of PO2 and PCO2, while a monocrystalline antimony pH electrode was used for simultaneous measurement of pH in vivo. Hypoxia, hypercapnia and relative acidity were found in synovial fluid and subchondral bone of knees with synovitis. The metabolic environment of synovial fluid and subchondral bone was considerably changed at the 3-week stage of experimental osteoarthritis and this was probably secondary to regional venous congestion.

Comparison of joint degeneration models. Surgical instability and repetitive impulsive loading

We used surgical instability and repetitive impulsive loading in rabbits to initiate degenerative changes in knee joints. Synovial membrane and cartilage samples were examined by light and electron microscopy. Early synovial inflammation at three days postoperatively preceded cartilage destruction in the instability model. Synovial inflammation was only apparent after eight weeks in the loading model and increased subsequently to cartilage destruction. Cartilage breakdown was focal and limited to the weight-bearing area. Comparison of the histological data of the two arthrosis models suggests that different inductive mechanisms may be involved in cartilage degeneration, but in both models the inflammatory changes appeared to be secondary to mechanical factors.

Joint reaction to polyethylene implantation: a method for inducing osteoarthritic change and osteophyte formation in the rabbit knee joint

Joint lesions were induced by implantation of a rigid piece of polyethylene sutured under the patella and quadriceps tendon of the rabbit's right knee. Compared to the left sham-operated knee, follow-up studies revealed progressive changes that consisted of early and transient synovial hyperemia and proliferation and late osteoarthritis. By day 7 after surgery, soft synovial-like tissue proliferated around the implant and the articular margins of the femoral trochlea indicating primitive "osteophytic" protuberances (synoviophytes). By day 15 after surgery, the synoviophytes had acquired a more solid consistency and were composed mostly of fibrocartilage covered by a fibro-cellular synovial lining (chondrophytes). By that time, this tissue was invaded with vascular channels; signs of ossification were already present in the deepest layer adjacent to bone. Between the 2nd and 12th weeks, this fibro-cartilaginous tissue, except for the surface fibrous or fibrocartilaginous layer, was progressively replaced by immature bone (osteophyte). Secondary bone remodeling started soon after the first lamellae of immature bone were deposited. Complete integration of the osteophyte into the distal femur occurred during the 2nd and 3rd month.