The effects of postoperative joint immobilization on articular cartilage degeneration following meniscectomy

Comparison between in vitro and in vivo cartilage overloading studies based on a systematic literature review

Methodological differences between in vitro and in vivo studies on cartilage overloading complicate the comparison of outcomes. The rationale of the current review was to (i) identify consistencies and inconsistencies between in vitro and in vivo studies on mechanically-induced structural damage in articular cartilage, such that variables worth interesting to further explore using either one of these approaches can be identified; and (ii) suggest how the methodologies of both approaches may be adjusted to facilitate easier comparison and therewith stimulate translation of results between in vivo and in vitro studies. This study is anticipated to enhance our understanding of the development of osteoarthritis, and to reduce the number of in vivo studies. Generally, results of in vitro and in vivo studies are not contradicting. Both show subchondral bone damage and intact cartilage above a threshold value of impact energy. At lower loading rates, excessive loads may cause cartilage fissuring, decreased cell viability, collagen network de-structuring, decreased GAG content, an overall damage increase over time, and low ability to recover. This encourages further improvement of in vitro systems, to replace, reduce, and/or refine in vivo studies. However, differences in experimental set up and analyses complicate comparison of results. Ways to bridge the gap include (i) bringing in vitro set-ups closer to in vivo, for example, by aligning loading protocols and overlapping experimental timeframes; (ii) synchronizing analytical methods; and (iii) using computational models to translate conclusions from in vitro results to the in vivo environment and vice versa. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-11, 2018.

The OARSI histopathology initiative - recommendations for histological assessments of osteoarthritis in sheep and goats

OBJECTIVE

Sheep and goats are commonly used large animal species for studying pathogenesis and treatment of osteoarthritis (OA). This review focuses on the macroscopic and microscopic criteria for assessing OA in sheep and goats and recommends particular assessment criteria to assist standardization in the conduct and reporting of preclinical trials of OA.

METHODS

A review was conducted of all published OA studies using sheep and goats and the most common macroscopic, microscopic, or ultrastructural scoring systems were summarised. General recommendations regarding methods of OA assessment in the sheep and goat have been made and a preliminary study of their reliability and utility was undertaken.

RESULTS

The modified Mankin scoring system is recommended for semiquantitative histological assessment of OA due to its already widespread adoption, ease of use, similarity to scoring systems used for OA in humans, and its achievable inter-rater reliability. Specific recommendations are also provided for histological scoring of synovitis and scoring of macroscopic lesions of OA.

CONCLUSIONS

The proposed system for assessment of sheep and goat articular tissues appears to provide a useful versatile method to quantify OA change. It is hoped that by adopting more standardised quantitative outcome measures, better comparison between different studies and arthritis models will be possible. The suggested scoring systems can be modified in the future as our knowledge of disease pathophysiology advances.

Etiology and pathophysiology of osteoarthritis

Acute or chronic insult, including normal wear and tear, age, obesity, and joint injury, may initiate an imbalance between matrix synthesis and matrix degradation in healthy cartilage that promotes chondral loss and prevents cartilage self-repair. The structure of healthy cartilage and the pathophysiological mechanisms of its degradation are described, followed by descriptions of endogenous and exogenous factors believed to be involved in the progressive course of osteoarthritis. Studies cited include research from the community of sports medicine.

Comparison of the effects of caudal pole hemi-meniscectomy and complete medial meniscectomy in the canine stifle joint

OBJECTIVE

To compare the effects of caudal pole hemi-meniscectomy (CPHM) and complete medial meniscectomy (MM), specifically with respect to development of secondary osteoarthritis, in the stifle joints of clinically normal dogs.

ANIMALS

14 large-breed dogs.

PROCEDURE

Unilateral CPHM (7 dogs) or MM (7) was performed, and the left stifle joints served as untreated control joints. Gait was assessed in all dogs before surgery and at 4, 8, 12, and 16 weeks postoperatively. After euthanasia, joints were evaluated grossly; Mankin cartilage scores, subchondral bone density assessment, and articular cartilage proteoglycan extraction and western blot analyses of 3B3(-) and 7D4 epitopes were performed.

RESULTS

Weight distribution on control limbs exceeded that of treated limbs at 4 and 16 weeks after surgery in the CPHM group and at 4 and 8 weeks after surgery in the MM group; weight distribution was not significantly different between the 2 groups. After 16 weeks, incomplete meniscal regeneration and cartilage fibrillation on the medial aspect of the tibial plateau and medial femoral condyle were detected in treated joints in both groups. Mankin cartilage scores, subchondral bone density, and immunoexpression of 3B3(-) or 7D4 in articular cartilage in CPHM- or MM-treated joints were similar; 7D4 epitope concentration in synovial fluid was significantly greater in the MM-treated joints than in CPHM-treated joints.

CONCLUSIONS AND CLINICAL RELEVANCE

Overall severity of secondary osteoarthritis induced by CPHM and MM was similar. Investigation of 7D4 epitope concentration in synovial fluid suggested that CPHM was associated with less disruption of chondrocyte metabolism.

Simultaneous changes in the mechanical properties, quantitative collagen organization, and proteoglycan concentration of articular cartilage following canine meniscectomy

The mechanical properties and microstructure of articular cartilage from the canine tibial plateau were studied 12 weeks after total medial meniscectomy. The organization of the birefringent collagen network was measured with quantitative polarized light microscopy to determine the thickness and the degree of organization of the superficial and deep zones. The zonal concentration of sulfated glycosaminoglycan was quantified with digital densitometry of safranin-O staining. Equilibrium compressive and shear properties, as well as dynamic shear properties, were measured at sites adjacent to those of microstructural analysis. The results evinced significant loss of cartilage function following meniscectomy, with decreases of 20-50% in the compressive and shear moduli. There was no evidence of alterations in the degree of collagen fibrillar organization, although a complete loss of the surface zone was seen in 60% of the samples that underwent meniscectomy. Meniscectomy resulted in a decreased concentration of sulfated glycosaminoglycan, and significant positive correlations were found between the equilibrium compressive modulus and the glycosaminoglycan content. Furthermore, the shear properties of cartilage correlated directly with collagen fibrillar organization measured at the superficial zone of corresponding sites. These findings demonstrate that meniscectomy leads to impaired mechanical function of articular cartilage, with significant evidence of quantitative correlations between cartilage microstructure and mechanics.

Tensile properties of articular cartilage are altered by meniscectomy in a canine model of osteoarthritis

Loss of or damage to the meniscus alters the pattern of loading in the knee joint and frequently leads to cartilage degeneration and osteoarthritis. The mechanical properties of articular cartilage have been shown to reflect the extent of cartilage degeneration in human osteoarthritis and in experimental models of joint disease, but there is little experimental data documenting changes in cartilage mechanics following meniscectomy. We hypothesized that the tensile properties of the surface zone of articular cartilage are altered following total medial meniscectomy. Twelve mongrel dogs underwent complete resection of the medial meniscus in the right knee, and the femoral cartilage was studied 12 weeks after the operation. We performed uniaxial, tensile stress-relaxation tests to determine the equilibrium tensile modulus of surface-zone cartilage. Water and glycosaminoglycan content were also measured at site-matched locations. The tensile moduli of the cartilage decreased significantly following meniscectomy. The linear region modulus decreased by 40%, from 25.5 +/- 7.7 to 15.3 +/- 7.2 MPa. There was a weak (r = -0.45), but significant, correlation between the linear region modulus and the gross morphological grade for cartilage damage. Water and glycosaminoglycan content did not change following meniscectomy. Composition was not correlated with mechanical properties or morphological grade, suggesting that cartilage structure may play a more important role than composition in determining the mechanical properties. The observed decrease in cartilage material properties provides a quantitative measure of the loss of cartilage function following meniscectomy and reflects a pattern of change that is consistent with damage to the collagen-proteoglycan solid network.

Effects of intraarticular hyaluronan on matrix changes induced in the lateral meniscus by total medial meniscectomy and exercise

Total medial meniscectomy was performed in 12 adult merino sheep. Immediately after surgery, 8 animals received high-molecular-weight hyaluronan (HA) (1 mL, 10 mg/mL) and 4 were given sterile saline (1 mL) intraarticularly. Injections were given for 5 more weeks. In week 3 an exercise program, consisting of walking 24 km/wk, was initiated. This program was continued until the animals were killed at week 26 postmeniscectomy. At necropsy the lateral menisci were removed and divided into three concentric zones--inner, middle, and outer. Powdered aliquots of tissues from each zone were analyzed for collagen and hexuronate contents using colormetric methods. The glycosaminoglycans (GAGs)--chondroitin-O-sulfate (C-O-S), chondroitin-4-sulfate (C-4-S), chondroitin-6-sulfate (C-6-S), and dermatan sulfate (DS)--were determined using a high-performance liquid chromatography method. The lateral menisci from the joints of animals injected with HA showed higher hexuronate and GAG levels than those of controls. This increase was mainly due to C-6-S, which had highest levels in the inner and middle meniscal zones. In addition, dermatan sulfate levels increased significantly in the middle and outer zones of the lateral menisci compared with the same zones of the meniscus from the saline-treated group. Collagen and C-O-S levels were not statistically different from those of controls. These data suggest that intraarticular administration of high-molecular-weight HA immediately after open total medial meniscectomy may help preserve the proteoglycans in the lateral meniscus remaining in the joint.

The effects of intraarticular administration of hyaluronan in a model of early osteoarthritis in sheep. II. Cartilage composition and proteoglycan metabolism

A model of early osteoarthritis (OA) induced in ovine joints by medial meniscectomy was used to study the effects of two hyaluronan (HA) preparations (AHA and DHA) on cartilage composition and proteoglycan (PG) metabolism. DHA was an HA preparation with an average molecular weight (MW) of approximately 2.0 x 10(6) d, and AHA had an MW of approximately 8.0 x 10(5) d. Both preparations were administered intraarticularly once a week for 5 weeks starting 16 weeks after meniscectomy, and animals (n = 5) were killed 5 weeks after the last injection. Meniscectomized, saline-injected (n = 5) and nonoperated (n = 5) animals were used for controls. At necropsy, 3-mm-diameter full-depth cartilage plugs were sampled under sterile conditions from specific locations on the medial and lateral femoral condyles, tibial plateaus, patella, and trochlear groove. The cartilage plugs were cultured in Hams-F12 medium supplemented with 10% fetal calf serum for 24 hours, then for a further 48 hours in the presence of H2(35)SO4 to determine the biosynthesis of PGs. The percentage of 35S-PGs and sulfated glycosaminoglycans released into the media was also ascertained. The cartilage adjacent to the plugs was analyzed for collagen and proteoglycan content and differential extractability with guanidine hydrochloride (GuHCl) solutions. The extractability of PGs with 0.4 mol/L GuHCl (nondissociative conditions) was lower from the medial femoral cartilages of the DHA-treated group than from the corresponding saline-treated group. In contrast, the release of 35S-PGs from the tibial cartilages of the DHA-treated animals was higher than in the saline-treated group. The biosynthesis of 35S-PGs, determined in vitro, for cartilage derived from the medial compartment was generally lower than for the lateral regions of the meniscectomized joints. The biosynthetic activity was further reduced in joints injected with the two HA preparations, but DHA reduced 35SO4 incorporation into PGs more than AHA. It was concluded that reduced biosynthesis of 35S-PGs and secretion into media was a consequence of increased loading of joints in the HA-treated animals rather than a direct effect of these preparations on chondrocyte metabolism.

Animal models of early osteoarthritis: their use for the evaluation of potential chondroprotective agents

Medial meniscectomy was undertaken in adult merino sheep and after 16 weeks exercise each group was administered five weekly intra-articular injections of saline, pentosan polysulphate (PPS), hyaluronic acid (HA) or a combination of PPS + HA. Gait analysis and x-rays were undertaken before and after drug treatment. At sacrifice (26 weeks), joints were examined for gross pathological and histochemical changes. Only the PPS-treated group showed an improvement in gait, with low radiological and histology scores. The HA-treated group showed similar but less significant changes to these parameters.

Articular cartilage changes following meniscal lesions. Repair and meniscectomy studied in the rabbit knee

A well-defined, longitudinal lesion in the avascular part of the medial meniscus of the right knee was made in 30 rabbits. After 3 months, the lesion was repaired surgically in 12 rabbits, was untreated in 12 rabbits, and a meniscectomy was performed in 6 rabbits. The articular cartilage was studied macroscopically and microscopically at 3-month intervals. Cartilage changes 3 months after meniscectomy were more pronounced than after meniscal repair or than in untreated lesions. However, meniscal repair did not reverse the cartilage changes.

Chondroprotective action of salmon calcitonin in experimental arthropathies

To assess whether calcitonin exerts an influence on cartilage, three models of arthropathies in rabbits--representing three different modes of cartilage destruction--were used: (1) corticosteroid administration (endocrinological disturbances model); (2) meniscectomy (mechanical stress model); and (3) immobilization of the hind leg (nutritional disorder model). After 12 weeks of methylprednisolone (MP) administration, the rabbit femur heads displayed cartilage erosions, marked decrease of glycosaminoglycans (GAG) content, and narrowing of joint spaces. Elevation of serum uronic acid, activity of alkaline phosphatase, and calmodulin content was evident. All these changes were minimal--close to normal--in the group treated for 12 weeks with MP + salmon calcitonin (sCT). Partial meniscectomy and hind leg immobilization caused statistically significant loss of GAG from the cartilage and narrowing of the knee joint space during the same experimental period, 12 weeks. In both these models the groups of rabbits treated simultaneously with sCT showed only insignificantly smaller joint spaces and GAG content. These results support our hypothesis of a chondroprotective property of calcitonin. However, the mechanism through which calcitonin influences joint cartilage remains unknown. A direct effect of calcitonin on cultivated chondrocytes, as well as the role of calmodulin, beta-endorphins, calcium, and interleukin-1 in the process are discussed.

Systemic administration of glycosaminoglycan polysulphate (arteparon) provides partial protection of articular cartilage from damage produced by meniscectomy in the canine

Bilateral medial meniscectomy was undertaken in 14 mature beagles. Another two underwent arthrotomy (sham-operated controls). One week after surgery, six of the meniscectomised animals were administered glycosaminoglycan polysulphate (Arteparon) (2 mg/kg) subcutaneously three times a week for 3 weeks, then twice weekly until killed 23 weeks later. Two months before death all animals were given Na2(35)SO4 (1.0 mCi/kg) intravenously. At autopsy, articular cartilage (AC) from the medial and lateral compartments, as well as from the femoral trochlear groove and femoral head, was sampled. Proteoglycans (PGs) were isolated by 4.0 M Guanidine hydrochloride (GuHCl) extraction of AC and purified by ultracentrifugation. The PG monomers were assayed for hexuronic acid, protein, and hexosamines (galactosamine/glucosamine), and their ability to aggregate. The results indicated that Arteparon provided some protective effect to AC in the meniscectomised compartment as demonstrated histologically by reduced surface fibrillation, diminished chondrocyte cloning, and maintenance of alcianophilia. The levels of PGs and hexuronate-protein ratios in medial AC of drug-treated meniscectomised animals were found to be comparable to sham controls, whereas these parameters in the nondrug-treated meniscectomized group were depressed.

Microinjury to the synovial membrane may cause disaggregation of proteoglycans in rabbit knee joint articular cartilage

Proteoglycans (PGs) isolated from articular cartilage (AC) of mature rabbits subjected to two or more consecutive intraarticular (IA) injections of sterile saline 24 h apart showed an aggregation defect in the presence of excess hyaluronic acid (HA). Although the PG contents of experimental and control cartilages were indistinguishable, a higher proportion of PGs were extractable from the 3 X IA tissues, as assessed by uronic acid analysis. Proteoglycans from experimental and control cartilages when examined by Sepharose CL-2B chromatography showed two subunit populations, the smaller (KAV = 0.70) containing more ketatan sulphate than the larger (KAV = 0.31). Cultures of AC from IA joints released more 35SO4-labelled PGs into the media over 72 h than control tissues and consisted mainly of PG degradation products although 20% could aggregate in the presence of HA. Examination of PG aggregation 2 weeks after 2 X IA or 3 X IA injections showed that the defect initiated was still present; however, cartilage of immature rabbits was not affected by the 2 X IA procedure.