Etiological considerations of the loose shoulder from a biochemical point of view--biochemical studies on collagen from deltoid and pectoral muscles and skin]

In order to elucidate the etiology of the loose shoulder, biochemical characteristics of deltoid and major pectoral muscles and skin collagen from patients with loose shoulder have been investigated. Amounts of soluble collagen, reducible cross-links of collagen and their precursors in both muscles and skin from the loose shoulder were found to be higher than those in the control. These data suggest that soft tissues, especially deltoid muscles, of patients with loose shoulder contain relatively immature collagen fibers compared with normal shoulders. In re-operation cases of the loose shoulder, the collagen fibers in skin were more immature, which may reflect the clinical features of the disease.     

An immunohistochemical study of the dorsal capsule of the lumbar and thoracic facet joints

STUDY DESIGN: The molecular composition of the extracellular matrix in the dorsal capsules of lumbar and thoracic facet joints was analyzed immunohistochemically. OBJECTIVES: To determine whether the immunohistochemical profile of the lumbar joint capsule suggests a role of the capsule in limiting axial rotation of the lumbar motion segment. SUMMARY OF BACKGROUND DATA: During axial rotation of the lumbar vertebrae, the axis of rotation shifts toward the facet joints in the direction of rotation. Thus, the capsule of the opposing joint should become tensed and wrap around the inferior articular process. Previous studies suggest that wrap-around ligaments are fibrocartilaginous. However, thoracic joint capsules are largely shielded from such loading and should be purely fibrous. METHODS: Dorsal capsules were removed from lumbar and thoracic facet joints of six adult cadavers. Specimens were immunolabeled with monoclonal antibodies for collagens, chondroitin, dermatan and keratan sulfates, versican, tenascin, aggrecan and link protein. Antibody binding was detected using the Vectastain ABC 'Elite' peroxidase kit (Vector Laboratories, Inc., Burlingame, CA). RESULTS: Both lumbar and thoracic joint capsules immunolabelled for most glycosaminoglycans and for Type I, III and VI collagens. However, labeling for Type II collagen, chondroitin-6-sulfate, aggrecan, and link protein was restricted to lumbar capsules. Such labeling was constantly seen at entheses and occasionally in the midsubstance. CONCLUSIONS: The molecular composition of the lumbar joint capsule suggests that it acts as a fibrocartilaginous, 'wrap-around' ligament that withstands compression in addition to tension during torsional movements of the lumbar spine. It wraps around the inferior articular process as rotation occurs and limits further movement.     

Scar formation and ligament healing

Ligaments are highly organized, dense, fibrous connective-tissue structures that provide stability to joints and participate in joint proprioception. Injuries to ligaments induce a healing response that is characterized by the formation of a scar. The scar tissue is weaker, larger and creeps more than normal ligament and is associated with an increased amount of minor collagens (types III, V and VI), decreased collagen cross-links and an increased amount of glycosaminoglycans. Studies have shown that certain surgical variables alter the healing of ligaments. Such factors include the size of gap between the healing ligament ends, the use of motion in a stable joint and the presence of multiple ligamentous injuries. Research on ligament healing includes studies on low-load and failure-load properties, alterations in the expression of matrix molecules, cytokine modulation of healing and gene therapy as a method to alter matrix protein and cytokine production.     

Alterations in collagen synthesis after transection of peripheral nerves

In order to elucidate the mechanisms of fibrosis during Wallerian degeneration after peripheral nerve injuries, the biochemical and immunohistochemical changes in collagen from posterior tibial nerves of albino rabbits have been analyzed after transection of the sciatic nerves. The total amount of collagens in the posterior tibial nerve was found to increase progressively after 2 weeks post-neurectomy. The amount of total soluble collagen and the reducible cross-links were also increased as time advanced after surgery. There was no significant change in the synthesis of genetically distinct types of collagens after neurectomy. The immunohistological study showed that Type I and Type III collagens were increased remarkably in epi- and endoneurium. These findings indicate that the fibrosis of peripheral nerve during Wallerian degeneration is most likely due to the progressive formation of immature collagen fibers in the tissues, rather than the decrease in the amount of nerve proteins as previously discussed.     

Histopathological Evaluation of Mechanoreceptors in the Metatarsophalangeal Joint Capsule in Hallux Valgus

To date, we could find no study concerning the relationship between mechanoreceptors in the joint capsule of the first metatarsophalangeal joint and hallux valgus deformity. We aimed to investigate the presence of mechanoreceptors in samples obtained from the first metatarsophalangeal joint capsules of patients with hallux valgus deformity to improve our understanding of the clinical and histopathological features of the disease. Samples were taken from the first metatarsophalangeal joint capsules of 13 fresh-frozen cadavers with normal anatomy (controls) and 29 patients undergoing surgery for hallux valgus (cases). For light microscopy, excised specimens were fixed in 10% formaldehyde and processed for routine histopathological investigation. All samples were dehydrated in a series of ethanol, cleared in xylene, and embedded in paraffin. Orientation of collagen fibers was determined on Masson's trichrome–stained sections, and mechanoreceptors were evaluated on S-100-immunostained sections. In the sections stained with Masson's trichrome, the orientation of collagen fibers was regular in the control group. However, coarse and disoriented collagen bundles were observed in the hallux valgus cases (P ≤ .05). S-100 immunostaining was positive in the sections of both the cases and controls. Finally, free nerve endings were more abundant in the samples obtained from the capsules of hallux valgus cases than from the control group (P ≤ .05). An increase in the number of free nerve endings within the capsules of the first metatarsophalangeal joints in feet with hallux valgus deformity might have a role in the development of clinically relevant joint pain and instability.     

Radiographic analysis of the acromion in the loose shoulder

To investigate the contribution of bony stability to the pathogenesis of the loose shoulder, geometric parameters of the acromion by use of cineradiography were evaluated in patients with a loose shoulder and compared with those in the normal shoulder. One hundred twenty healthy individuals and eighty-two patients were enrolled. To evaluate the size of the acromion and the coverage of the humeral head by the acromion, the anterior width of the acromion and three angle parameters were measured. The findings demonstrated that the loose shoulder had a relatively smaller and more upwardly inclined acromion that was against the glenoid and provided less coverage of the humeral head. These characteristics of the acromion may contribute to the hypermobility and functional instability of the shoulder joint observed in patients with a loose shoulder. Therefore, a radiographic evaluation of the geometry of the acromion is important to determine the pathogenesis of the loose shoulder.     

Types of collagen in breast capsules

Representative sections of the capsules that envelop surgically implanted silicone were analyzed for their collagen content. The specimens were biopsied (as incidental procedures) as the opportunities arose. All four classes of capsules as codified clinically and those surrounding tissue expanders are represented. The ages of the capsules ranged from 6 weeks to 13 years. Eighteen specimens were examined by slab gel electrophoresis. Type I collagen predominated in all of the electrophoretic patterns. Type III collagen was consistently present in lesser concentrations. Type V collagen was consistently present as a small fraction. There was no evident correlation between the concentrations of the component collagens and the clinically assessed class of the capsules or of those from around tissue expanders, but there was a correlation to the age of the capsules. The electrophoretic patterns of the collagens of this study are indistinguishable from the (previously reported) analyses of (cutaneous) scar.     

Collagen morphology in human skin and scar tissue: no adaptations in response to mechanical loading at joints

Dermal collagen displays a random-like structure that has a major role in strength and function of the human integument. It is hypothesised that collagen bundles align in a parallel fashion in the direction of mechanical tension during scarring, which may explain the problematic scar formation that occurs specifically at joints. Scar tissue and normal skin were biopsied from joints and control areas and evaluated by the Fourier analysis. Collagen orientation was represented by an index ranging from 0 (perfectly random) to 1 (perfectly parallel). Collagen bundle packing signifies the average distance between the centres of collagen bundles. No differences were shown in collagen morphology of scar tissue and normal skin between joints and control areas. Normal skin had a significantly lower collagen orientation index than scar tissue (0.26 versus 0.44, P<0.001). The bundle packing of scar tissue differed significantly from normal skin (18.1 microm versus 23.7 microm, P<0.001). Collagen appeared less parallel orientated in deep dermis compared to superficial dermis especially for normal skin (0.27 versus 0.33, P=0.06). Normal skin had a less parallel organisation in sections that were cut parallel compared to those that were cut perpendicular to the epidermis (0.24 versus 0.30, P=0.02). Collagen orientation of scar tissue is more parallel compared to normal skin. Morphology differs with respect to superficial and deep dermal layers and parallel and perpendicular planes, but appears not to respond to mechanical tension.     

1991 Volvo Award in basic sciences. Collagen types around the cells of the intervertebral disc and cartilage end plate: an immunolocalization study

Several types of collagen are known to exist in the intervertebral disc in addition to the fibrillar collagens, Types I and II. Although they constitute only a small percentage of the total collagen content, these minor collagens may have important functions. This study was designed to investigate the presence of Types I, II, III, IV, VI, and IX collagens in the intervertebral disc and cartilage end plate by immunohistochemistry, thereby establishing their location within the tissues. Types III and VI collagen have a pericellular distribution in animal and human tissue. No staining for Type IX collagen was present in normal human disc, but in rat and bovine intervertebral disc, it was also located pericellularly. These results show that cells of the intervertebral disc and cartilage end plate sit in fibrous capsules, forming chondrons similar to those described in articular cartilage. In pathologic tissue the amount and distribution of the collagen types, and the organization of the pericellular capsule, differ from that seen in control material.     

Arthroscopic Retrieval of over 100 Loose Bodies in Shoulder Synovial Chondromatosis: A Case Report and Review of Literature

Synovial chondromatosis is a rare and benign condition of unknown cause. It is also known as synovial osteochondromatosis. It is characterized by involvement of the synovial tissue, which lines various joints of our body. Initial symptoms range from pain in the joint, locking of the joint at times, especially the knee, to arthritis of the joint that is a late feature of this condition. Although large joints such as the knee are commonly affected, involvement of the shoulder joint is a rare occurrence. Historically an open arthrotomy was preferred for removal of loose bodies coupled with a thorough synovectomy. However, arthroscopy for loose body retrieval has gained popularity over the past two decades. Arthroscopic surgery is an extremely skilled procedure and there is a learning curve for operating in certain anatomical areas such as the shoulder. However, not only does an arthroscopy provide the surgeon with an excellent view of the shoulder but the patient also has a faster recovery. We report a rare case of shoulder synovial chondromatosis in which more than 100 loose bodies were successfully retrieved by an arthroscopy in an individual who had an excellent outcome post‐surgery, reaffirming our faith in the procedure. A detailed literature review of arthroscopic procedures is also presented.     

Knee and ankle: human joints with different susceptibility to osteoarthritis reveal different cartilage cellularity and matrix synthesis in vitro

Clinical experience shows that symptoms and pathological changes of primary osteoarthritis (OA) are more frequent and severer in the knee than in the ankle joint. The different anatomy of both weight-bearing joints implies that biomechanical differences may contribute to their varying susceptibility to OA. This study aims at elucidating other non-biomechanical factors to explain these fundamental differences in secondary OA prevalence. Human cartilage of matched ankle and knee joints from organ donors was dissected in full-thickness slices or in layers. The DNA content for estimation of cell number was analyzed fluorometrically. Chondrocytes were cultured in organ culture or after isolation in alginate. Proteoglycan synthesis was determined by ³⁵S incorporation, and collagen synthesis by ³H-proline incorporation. This study demonstrates that in both joints, the cell density sharply declines between newborn and young infant ages. In addition, cartilage from the ankle joint is significantly more cellular than cartilage from the knee joint. In general, ankle chondrocytes synthesize more proteoglycans (PGs) and collagens than knee chondrocytes, and deep zone chondrocytes more than superficial zone chondrocytes. The biochemical properties of chondrocytes of the ankle and knee joints differ significantly and might play an important role in the pathogenesis of OA. Received: 24 June 2000     

Fine powdering exposes the mineral-protected collagen of bone to protease digestion

Summary The method of heat-denaturation and trypsin digestion was used to dissect bone biochemically into mineral-protected and mineral-unprotected pools of collagenous matrix. It was found that varying the particle size of the bone powder had a profound effect on the results. Using mature bovine cortical bone, the observed pool of “unmineralized” (mineral-unprotected) collagen could be varied from 2% to more than 60% of the total bone collagen simply by decreasing the particle size of the bone sample from greater than 1 mm to less than 38 μm. No major differences were seen in the contents of hydroxypyridinium cross-links between the collagens of the trypsin-soluble and trypsin-insoluble pools from the fine powders, contrary to earlier reports. A trend to a higher content of these cross-links was evident, however, in the very small collagen pool extracted from the coarsest bone particles. Similar extraction differences were noted using bacterial collagenase to probe for mineral-protected vs. mineral-unprotected domains of bone collagen. In summary, the biochemical dissection results appear largely to be an artifact of the powdering technique, the shear energies of which presumably destroy the intimate physical relationship between the mineral crystallites and the collagen fibrils at the fractured surfaces of the bone particles. As the fractured surface area increases with decreasing particle size so the fraction of protease degradable collagen increases. Since powdering is routinely adopted for many structural studies on both the mineral and organic phases of bone, the findings on finely powdered bone should be interpreted cautiously.     

Synovial osteochondromatosis in the subacromial bursa

Synovial osteochondromatosis may occur within an otherwise normal synovial joint (primary disease), within a diseased joint (secondary disease), within tendon sheaths, and within extraarticular bursal cavities. Each of these four types of disease can present in one of three progressive morphologic stages in which the intrasynovial proliferations of cartilage and bone break free to form loose bodies. A 61-year-old man presented with loose bodies about his right shoulder. This case report demonstrates that the disease was a true example of bursal osteochondromatosis of the subacromial bursa, Stage III, rather than synovial osteochondromatosis of the shoulder joint. Well-documented cases of bursal osteochondromatosis are rare.     

Innervation of cervical ventral facet joint capsule: Histological evidence

AIM: To assess the presence of nerves in ventral facet joint capsules as facet capsules are generally implicated in neck pain.METHODS: Twenty-four ventral cervical facet joint capsules were harvested from 3 unembalmed cadavers. Paraffin sections from these capsules were processed to identify neurofilament and substance P immunoreactive fibers. Nerve fiber presence was also verified by a silver impregnation method.RESULTS: Neurofilament reactive fibers were observed in sections from 9 capsules. They were observed in areas with collagen fibers and areas with irregular connective tissue. Substance P reactive nerve fibers were found in sections from 7 capsules in similar areas. Silver impregnation also revealed the presence of nerve fibers. The nerve fibers were also found as bundles in the lateral margins of the capsule. A Pacinian corpuscle-like ending was also observed in one specimen.CONCLUSION: Nerve fibers revealed by neurofilament immunoreactivity and silver staining support innervation of the ventral aspect of the facet joint capsule. The presence of substance P reactive fibers supports the potential role of these elements in mediating pain. The presence of a Pacinian-like ending implicates a potential role in joint movement.     

Collagen cross-links as a determinant of bone quality: a possible explanation for bone fragility in aging, osteoporosis, and diabetes mellitus

Collagen cross-linking, a major post-translational modification of collagen, plays important roles in the biological and biomechanical features of bone. Collagen cross-links can be divided into lysyl hydroxylase and lysyl oxidase-mediated enzymatic immature divalent cross-links, mature trivalent pyridinoline and pyrrole cross-links, and glycation- or oxidation-induced non-enzymatic cross-links (advanced glycation end products) such as glucosepane and pentosidine. These types of cross-links differ in the mechanism of formation and in function. Material properties of newly synthesized collagen matrix may differ in tissue maturity and senescence from older matrix in terms of cross-link formation. Additionally, newly synthesized matrix in osteoporotic patients or diabetic patients may not necessarily be as well-made as age-matched healthy subjects. Data have accumulated that collagen cross-link formation affects not only the mineralization process but also microdamage formation. Consequently, collagen cross-linking is thought to affect the mechanical properties of bone. Furthermore, recent basic and clinical investigations of collagen cross-links seem to face a new era. For instance, serum or urine pentosidine levels are now being used to estimate future fracture risk in osteoporosis and diabetes. In this review, we describe age-related changes in collagen cross-links in bone and abnormalities of cross-links in osteoporosis and diabetes that have been reported in the literature.     

Effect of postoperative immobilisation on the regrowth of the knee joint semilunar cartilage: an experimental study

Bilateral total medial meniscectomy was undertaken in the knee joints of 12 adult greyhounds. One-half of the animals had one meniscectomised joint immobilised by an external fixation system for 5 weeks following meniscectomy. All animals were sacrificed 6 months after surgery. The menisci (regrown and normal) were examined for collagen content and analysed histochemically to assess collagen assembly and glycosaminoglycan (GAG) distribution. Although the collagen content of regrown tissues were not statistically different from normal medial or lateral menisci, the fibre development and GAGs were abnormal. It is concluded that movement following meniscectomy is likely beneficial to the matrix formation in the regenerating tissue, but this together with weight bearing may have a detrimental effect on articular cartilage of the medial joint compartment.     

Spatial organization of types I and II collagen in the canine meniscus.

The meniscus of the knee joint is a fibrocartilage mainly composed of type I collagen and smaller amounts of type II collagen. The distribution of type II collagen in the canine meniscus and its spatial relationship to type I collagen was examined by immunohistochemistry and confocal microscopy. Dorsal and coronal slices of the mid-section of medial and lateral menisci from the knee joints of skeletally mature dogs were predigested with Streptomyces hyaluronate lyase and bacterial Protease enzyme XXIV. Monoclonal antibodies against type I collagen (CP17L) and type II collagen (II-II6B3) and an anti-type II collagen polyclonal antibody (AB759) were employed. The staining for type II collagen in the extracellular matrix of hyaline articular cartilage was diffuse without any identifiable spatial organization. In striking contrast, type II collagen in the fibrocartilage of the meniscus stained as an organized network. Type II collagen was distributed throughout the meniscus with the exception of the outer zone containing the blood vessels. Coronal and dorsal staining of the meniscus showed bundles of circumferential fibrils of type I that colocalized with type II collagen in specific sites. These bundles were enwrapped in a second organizational fibrillar system of types I and II collagen that also colocalized. Bundles of circumferential fibrils appeared in cross-section in coronal sections as dots within the interstitial spaces framed by the network of types I and II collagen of the second system. Confocal overlays showed that types I and II collagens were superimposed, suggesting a close spatial proximity between the two collagens. The cells were confined to the types I and II collagen fibrils that enwrapped the bundles. A striking feature of the radial tie fibers was patches of type II collagen without colocalized type I collagen. Our study reveals a unique network of type II collagen in fibrocartilage of the meniscus that serves as a morphological distinction between fibro- and hyaline cartilage.     

Blocking collagen fibril formation in injured knees reduces flexion contracture in a rabbit model

Post‐traumatic joint contracture is a frequent orthopaedic complication that limits the movement of injured joints, thereby severely impairing affected patients. Non‐surgical and surgical treatments for joint contracture often fail to improve the range of motion. In this study, we tested a hypothesis that limiting the formation of collagen‐rich tissue in the capsules of injured joints would reduce the consequences of the fibrotic response and improve joint mobility. We targeted the formation of collagen fibrils, the main component of fibrotic deposits formed within the tissues of injured joints, by employing a relevant rabbit model to test the utility of a custom‐engineered antibody. The antibody was delivered directly to the cavities of injured knees in order to block the formation of collagen fibrils produced in response to injury. In comparison to the non‐treated control, mechanical tests of the antibody‐treated knees demonstrated a significant reduction of flexion contracture. Detailed microscopic and biochemical studies verified that this reduction resulted from the antibody‐mediated blocking of the assembly of collagen fibrils. These findings indicate that extracellular processes associated with excessive formation of fibrotic tissue represent a valid target for limiting post‐traumatic joint stiffness. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1038–1046, 2017.

     

Joint capsule matrix turnover in a rabbit model of chronic joint contractures: Correlation with human contractures.

To evaluate changes in matrix molecules of the joint capsule, the right knees of 24 skeletally mature female NZW rabbits were immobilized while the contralateral limb served as an unoperated control. The immobilization was discontinued at 8 weeks and the rabbits were divided among four groups (n = 6) based on the number of weeks the right knees were remobilized: 0, 8, 16, or 32. Three rabbits (six knees) that did not have operations provided normal control joint capsules. The mRNA levels for collagen types I, II, and III, and MMP-1 and -13 were significantly increased in the joint capsules of the contracture knees in all groups when compared to normal and contralateral limb joint capsules. In contrast, the mRNA levels for TIMP-1, -2, and -3 were decreased in the joint capsules of the contracture knees in all groups when compared to normal and contralateral limb joint capsules. The mRNA levels for lumican and decorin were increased in the joint capsules of the contracture knees in all groups when compared to normal capsules. Many of the changes observed in this animal model are similar to those observed in human joint capsules from posttraumatic elbow contractures, supporting the value of this rabbit model.     

Auxiliary proteins that facilitate formation of collagen‐rich deposits in the posterior knee capsule in a rabbit‐based joint contracture model

Post‐traumatic joint contracture is a debilitating consequence of trauma or surgical procedures. It is associated with fibrosis that develops regardless of the nature of initial trauma and results from complex biological processes associated with inflammation and cell activation. These processes accelerate production of structural elements of the extracellular matrix, particularly collagen fibrils. Although the increased production of collagenous proteins has been demonstrated in tissues of contracted joints, researchers have not yet determined the complex protein machinery needed for the biosynthesis of collagen molecules and for their assembly into fibrils. Consequently, the purpose of our study was to investigate key enzymes and protein chaperones needed to produce collagen‐rich deposits. Using a rabbit model of joint contracture, our biochemical and histological assays indicated changes in the expression patterns of heat shock protein 47 and the α‐subunit of prolyl 4‐hydroxylase, key proteins in processing nascent collagen chains. Moreover, our study shows that the abnormal organization of collagen fibrils in the posterior capsules of injured knees, rather than excessive formation of fibril‐stabilizing cross‐links, may be a key reason for observed changes in the mechanical characteristics of injured joints. This result sheds new light on pathomechanisms of joint contraction, and identifies potentially attractive anti‐fibrotic targets. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:489–501, 2016.