More histologic and ultrastructural degenerative signs in the subscapularis tendon and the joint capsule in male patients with shoulder impingement.

PURPOSE: The purpose of the present study was to analyze biopsy samples from the subscapularis tendon and from the joint capsule from male patients with shoulder impingement syndrome (SAIS) and compare them with samples from male patients with post-traumatic recurrent shoulder instability. The hypothesis of the study was that patients with SAIS would have more histologic and ultrastructural degenerative changes in their subscapularis tendon and joint capsule than patients with post-traumatic recurrent shoulder instability. METHODS: Male patients scheduled for surgery, with either subacromial decompression or Bankart reconstruction, were included. Four biopsies from each patient were obtained from the capsule and four from the subscapularis tendon during arthroscopic surgery. The histologic characteristics and the presence of glycosaminoglycans were assessed using the light microscope, and the ultrastructure was assessed using a transmission electron microscope. RESULTS: Eight patients, median age 53 (45-74) years (p < 0.0001), were included in the impingement group, and 12 patients, median age 27 (22-48) years, were included in the instability group. The histologic assessment revealed significantly higher cellularity and total degeneration score in the capsule (p = 0.016 and p = 0.014 respectively) in patients with subacromial impingement compared with the instability patients. The corresponding finding was not made for the subscapularis tendon. The ultrastructural evaluation revealed that the instability patients had more fibrils with a large diameter (indicating less degeneration) in both the subscapularis tendon and the capsule compared with the impingement patients (p < 0.0001). CONCLUSION: Male patients with subacromial impingement have more histologic and ultrastructural degenerative changes in their shoulder compared with patients with post-traumatic recurrent shoulder instability. CLINICAL RELEVANCE: It appears that in patients with subacromial impingement, the whole shoulder joint is affected and not only the subacromial space. It is the opinion of the authors that intra-articular therapeutic injections could be tried more often in these patients. LEVEL OF EVIDENCE: III.

A method for predicting collagen fiber realignment in non-planar tissue surfaces as applied to glenohumeral capsule during clinically relevant deformation.

Previously developed experimental methods to characterize micro-structural tissue changes under planar mechanical loading may not be applicable for clinically relevant cases. Such limitation stems from the fact that soft tissues, represented by two-dimensional surfaces, generally do not undergo planar deformations in vivo. To address the problem, a method was developed to directly predict changes in the collagen fiber distribution of nonplanar tissue surfaces following 3D deformation. Assuming that the collagen fiber distribution was known in the un-deformed configuration via experimental methods, changes in the fiber distribution were predicted using 3D deformation. As this method was solely based on kinematics and did not require solving the stress balance equations, the computational efforts were much reduced. In other words, with the assumption of affine deformation, the deformed collagen fiber distribution was calculated using only the deformation gradient tensor (obtained via an in-plane convective curvilinear coordinate system) and the associated un-deformed collagen fiber distribution. The new method was then applied to the glenohumeral capsule during simulated clinical exams. To quantify deformation, positional markers were attached to the capsule and their 3D coordinates were recorded in the reference position and three clinically relevant joint positions. Our results showed that at 60deg of external rotation, the glenoid side of the posterior axillary pouch had significant changes in fiber distribution in comparison to the other sub-regions. The larger degree of collagen fiber alignment on the glenoid side suggests that this region is more prone to injury. It also compares well with previous experimental and clinical studies indicating maximum principle strains to be greater on the glenoid compared to the humeral side. An advantage of the new method is that it can also be easily applied to map experimentally measured collagen fiber distribution (obtained via methods that require flattening of tissue) to their in vivo nonplanar configuration. Thus, the new method could be applied to many other nonplanar fibrous tissues such as the ocular shell, heart valves, and blood vessels.

Characterization of wear debris in total elbow arthroplasty.

BACKGROUND: The purpose of this study was to evaluate wear debris in periprosthetic tissues at the time of revision total elbow arthroplasty. Polyethylene, metallic, and bone cement debris were characterized, and the tissue response was quantified. MATERIALS AND METHODS: Capsular and medullary tissue samples were collected during revision surgery. Polyethylene debris was characterized by scanning electron microscopy after tissue digestion. The concentrations of metal and cement debris were quantified by inductively coupled plasma mass spectrometry. Tissue response was graded with a semiquantitative histologic method. RESULTS: Polyethylene particle size varied from the submicron range to over 100 µm. The mean diameter ranged from 0.6 µm to about 1 µm. Particles in the synovial tissues were larger and less abundant than those in tissues from the medullary canal. Cement, titanium alloy, and low levels of cobalt-chrome debris were also present, with cement predominating over metal debris. Histiocyte response was associated with small polyethylene particles (0.5-2 µm), and giant cells were associated with large polyethylene particles (>2 µm). Histiocyte scores positively correlated with the polyethylene particle number and the presence of metal. DISCUSSION: We have shown that periprosthetic tissues of total elbow patients who have undergone revision for loosening and osteolysis contain polyethylene, cement, and metal debris. Although the polyethylene particles were of a size and shape that have been previously shown to result in activation of phagocytic cells, osteolysis after total elbow arthroplasty is a multimodal process. Because of the presence of multiple wear particle sources, a cause-and-effect relationship between polyethylene debris and osteolysis cannot be established with certainty.

Tetrandrine inhibits the occurrence and development of frozen shoulder by inhibiting inflammation, angiogenesis, and fibrosis.

BACKGROUND: Frozen shoulders (FS) is a major clinical concern, where chronic synovial inflammation, abnormal angiogenesis, and fibrosis represent the critical pathologies in the glenohumeral capsule. However, no pharmacotherapy has been introduced to treat this pathology. Tetrandrine (TET) has been proposed as a treatment for many diseases due to its strong anti-inflammatory, anti-angiogenic, and anti-fibrotic effects. PURPOSE: To study the anti-inflammatory, anti-angiogenic, and anti-fibrotic effects of TET on FS, and identify whether TET can prevent the development of FS in rats. STUDY DESIGN: A controlled laboratory study. METHODS: Forty-eight male Sprague-Dawley (SD) rats were randomly divided into control, TET, and FS groups. The TET group was intraperitoneally injected with TET every 2 days. TET and saline treatment were started on the day of FS surgery. After 8 weeks, the animals were sacrificed, and samples were collected for X-ray examination, glenohumeral range of motion (ROM) evaluation, histology and immunohistochemistry analysis, transmission electron microscopy (TEM) observation, and profibrogenic factors as well as proinflammatory cytokines measurements. RESULTS: No significant difference in shoulder ROM was observed between the TET and control groups, but a significant difference was noted between these groups and the FS group (P < 0.01). Immunohistochemical staining showed no abnormal angiogenesis or fibrosis in the TET group or the control group. However, significant angiogenesis, collagen remodeling, and fibrosis were observed in the FS group, and the expression and proportion of type I and type III collagen in the FS group were significantly higher than those in the TET group or the control group (P < 0.01). TEM observation showed that TET protected the ultrastructure of collagen fibrous reticular arrangement of the articular capsule and prevented the formation of scar-like fibrotic structures, which are unique to FS. The significantly increased expression of Smad7 and the suppressed expression of Smad 2 in the TET group compared with that of the FS group indicated that TET also significantly inhibited the TGF-ß1 intracellular signal pathway. The expression of profibrogenic factors and proinflammatory cytokines in the TET group and the control group was significantly lower than that in the TET group (P < 0.01). CONCLUSION: The results demonstrated that TET protected the normal reticular structure of the capsule during the freezing period and prevented the development of FS by inhibiting inflammation, angiogenesis, and fibrosis in a rat FS model. CLINICAL RELEVANCE: TET may be a safe and effective clinical medication for preventing and treating FS.

The anterior tibio-talar ligament: one reason for anterior ankle impingement.

The purpose of this study was the evaluation of the ankle's anterolateral ligament structures. We documented the anatomic situation of the ankle's anterolateral ligament structures in 33 Thiel-embalmed specimens. The ligaments had been isolated. We performed measurements on both length and orientation and additionally classified the ligaments. We also conducted histologic tissue staining. We were able to document a regular appearance of a so far not well-realized structure between the talus and the tibia, present in 26 (79%) specimens. Average length of this structure was 26 mm (in 20 degrees plantarflexion). The angular orientation in relation to the ant. tibio-fibular lig. was on average 43.7 degrees. This structure could be classified as being either isolated or widespread, with a further four sub-classifications for the orientation. Histologic staining showed parallel orientated dense collagen fibers as well as elastic fibers and hyaline cartilage in different stages of proliferation. In addition, there were neural fibers in the perivascular and the soft tissue. The histologic findings proved that the structure was a ligament. Since the ant. tibio-talar lig. is constantly present in most ankle joints, it could be considered as a regular finding. Its morphology and histology show that this ligament is loaded under tension as well as under compression. This could be one reason for anterior ankle impingement.

Collagenous microstructure of the glenoid labrum and biceps anchor.

The glenoid labrum is a significant passive stabilizer of the shoulder joint. However, its microstructural form remains largely unappreciated, particularly in the context of its variety of functions. The focus of labral microscopy has often been histology and, as such, there is very little appreciation of collagen composition and arrangement of the labrum, and hence the micromechanics of the structure. On transmission electron microscopy, significant differences in diameter, area and perimeter were noted in the two gross histological groups of collagen fibril visualized; this suggests a heterogeneous collagenous composition with potentially distinct mechanical function. Scanning electron microscopy demonstrated three distinct zones of interest: a superficial mesh, a dense circumferential braided core potentially able to accommodate hoop stresses, and a loosely packed peri-core zone. Confocal microscopy revealed an articular surface fine fibrillar mesh potentially able to reduce surface friction, bundles of circumferential encapsulated fibres in the bulk of the tissue, and bone anchoring fibres at the osseous interface. Varying microstructure throughout the depth of the labrum suggests a role in accommodating different types of loading. An understanding of the labral microstructure can lead to development of hypotheses based upon an appreciation of this component of material property. This may aid an educated approach to surgical timing and repair.

The thermal properties of bovine joint capsule. The basic science of laser- and radiofrequency-induced capsular shrinkage.

Orthopaedic surgeons have recently adapted the holmium: yttrium-aluminum-garnet (YAG) laser for the shrinkage of capsular tissues for treatment of glenohumeral instability. The molecular mechanism of capsular shrinkage has not been documented to date. This study examined the effects of heating on bovine calf knee capsule and subsequent shrinkage of the capsule. Capsule specimens were placed in a saline bath at temperatures ranging from 55 degrees to 75 degrees C for 1, 3, 5, and 10 minutes. Shrinkage was quantified by digital imaging, and the tissue was examined by light and polarized light microscopy. Tissue contraction was not measurable at or below 57.5 degrees C. At 60 degrees C, tissue shrinkage occurred with corresponding basophilic staining and loss of birefringence in collagen fibers. For specimens heated at 60 degrees C and 62 degrees C, shrinkage directly correlated with duration of thermal exposure. Maximal shrinkage of approximately 50% in length occurred at and above 65 degrees C with thermal exposures of 1 minute or greater. This study demonstrates that thermal shrinkage of bovine knee capsule correlates with denaturation of collagen fibers and depends on both time and temperature. Capsular shrinkage treatments may be performed with any energy source that is capable of well-controlled heating of capsular tissue and does not depend on the special properties of laser light.

Synovial tissue and synovial fluid.

Synovial tissue is a highly specialized tissue that keeps the articular joint well lubricated, and at the same time provides nutrients to the articular surface. A joint needs a small amount of synovial fluid to work. Although the tissue structure is simple, its function is highly sophisticated. Because synovial tissue is the target of most autoimmune diseases, joints need to be understood in their entirety to create new treatments for such immunological disorders.

The effect of nonablative laser energy on the ultrastructure of joint capsular collagen.

This study was designed to evaluate the effect of laser energy at nonablative levels on the ultrastructure of joint capsular collagen. The femoropatellar joint capsules of six mature New Zealand white rabbits were harvested immediately after death. Specimens were divided into three treatment groups (5, 10, and 15 watts) and one control group. Laser energy was applied using a holmium: YAG laser. Transmission electron microscopy showed significant ultrastructural alterations in collagenous architecture for all laser treatment groups, with increased fibril cross-sectional diameter for each of the treated groups. The fibrils began to lose their distinct edges and their periodical cross-striations at subsequently higher energy densities. A morphometric analysis showed that each subsequently higher laser energy caused a significant increase in collagen fibril diameter. Ultrastructural alteration of collagen fibril architecture caused by the thermal effect of laser energy is probably the dominant mechanism of laser-induced tissue shrinkage.

Effect of nonablative laser energy on the joint capsule: an in vivo rabbit study using a holmium:YAG laser.

BACKGROUND AND OBJECTIVE: The nonablative application of holmium:yttrium-aluminum-garnet (Ho:YAG) laser energy to the joint capsule of patients with glenohumeral instability has been found to shrink capsular tissue and to help stabilize the joint. The purpose of this study was to evaluate the effect of nonablative laser energy on the short-term histological properties of joint capsular tissue in an in vivo rabbit model. STUDY DESIGN/MATERIALS AND METHODS: Eighteen mature New Zealand white rabbits were used in this study. One randomly selected stifle was treated with laser energy, and the contralateral stifle was sham-operated. Animals were euthanized immediately after surgery (day 0), at 7 days postsurgery and 30 days postsurgery. Specimens were processed for histology and transmission electron microscopy. RESULTS: Laser-treated samples at day 0 showed diffuse hyalinization of collagen with nuclear karyorrhexis of fibroblasts. Laser-treated tissue at 7 days postsurgery revealed fibroblast proliferation around and into acellular hyalinized regions of collagen. At 30 days postlaser treatment, areas of fused collagen were greatly reduced as large reactive fibroblasts migrated and secreted matrix. CONCLUSION: This study illustrates the short-term in vivo tissue response to nonablative laser treatment, where acellular hyalinized regions of collagen are infiltrated by fibroblasts that have used the treated collagen as the framework for migration and secretion of new collagen matrix in order for tissue repair to proceed.

Ultrastructural study on adhesions in internal derangement of the temporomandibular joint.

PURPOSE: This study examined the ultrastructural characteristics of adhesions in the upper joint compartment of temporomandibular joint (TMJ). MATERIALS AND METHODS: Tissue biopsy specimens of adhesions were obtained during arthroscopic operation on 36 joints in 22 patients with internal derangement (ID). The biopsy specimens were examined by light and transmission electron microscopy. RESULTS: Adhesions were grossly divided into two types based on arthroscopic observation: 1) a band-like type, which connected the articular fossa and TMJ disc, and 2) a pseudowall-like type, which faced the synovial fluid and was lined by articular tissue. Two types of collagen arrangement were observed at the electron microscopic level: orderly arranged collagen bundles and randomly arranged collagen bundles. Orderly arranged collagen bundles were prominent in the band-like adhesions. In pseudowall-like adhesions, mainly the randomly arranged collagen bundles were seen. However, in some dense fiber parts, orderly arranged collagen bundles also were observed. In other pseudowall-like adhesions, only orderly arranged collagen bundles were seen. Elastic fibers were abundant in some pseudowall-like adhesions with randomly arranged collagen bundles. There were no elastic fibers in the band-like adhesions, some dense fiber parts of the pseudowall-like adhesion, pseudowall-like adhesions consisting of only orderly arranged collagen bundles, and in the synovial membrane. CONCLUSION: The different arrangement of collagen fibers and presence or absence of elastic fibers were observed in the two types of adhesions. These findings served to show that extracellular components correspond to a dysfunction involving an ID of TMJ.

The effect of radiofrequency energy on the ultrastructure of joint capsular collagen.

This study evaluated the effect of radiofrequency energy on the histological and ultrastructural appearance of joint capsular collagen. Femoropatellar joint capsular specimens from adult sheep were treated with one of three treatment temperatures (45 degrees C, 65 degrees C, and 85 degrees C) with a radiofrequency generator or served as control in a randomized block design. Twenty-four specimens (n = 6) were processed for histological examination as well as ultrastructural analysis using transmission electron microscopy. A computer-based area determination program was used to calculate the area affected in histological samples. Histological changes consisted of thermal tissue damage characterized by collagen fiber fusion and fibroblastic nuclear pyknosis at all application temperatures with clear demarcations between treated and untreated tissue. Mean tissue affected ranged from 50.4% for 85 degrees C to 22.5% for 45 degrees C. There was a strong correlation between treatment temperature and percent area affected (P < .001, R2 = .65). Ultrastructural alterations included a general increase in cross-sectional fibril diameter and loss of fibril size variation with increasing treatment temperature. Longitudinal sections of collagen fibrils showed increased fibril diameter and the loss of cross-striations in the treated groups. Thermally induced ultrastructural collagen fibril alteration is likely the predominant mechanism of tissue shrinkage caused by application of radiofrequency energy.

alpha-smooth muscle actin and contractile behavior of bovine meniscus cells seeded in type I and type II collagen-GAG matrices.

Many types of injuries to the meniscus of the knee joint result in defects that do not heal, leading to pain and dysfunction. Several ongoing investigations are developing porous absorbable matrices to be used alone or seeded with cultured cells to facilitate regeneration of this tissue. The objective of this study was to evaluate in vitro the contractile behavior of meniscal cells seeded in type I and type II collagen matrices. In many connective tissues, fibroblasts that have assumed a contractile phenotype (myofibroblasts) have been found to play an important role in healing and in pathological conditions. This phenotype, if expressed by meniscal cells, could affect their behavior in cell-seeded matrices developed for tissue engineering. In this study, the presence of a contractile actin isoform, alpha-smooth muscle (alpha-SM) actin, was assessed by immunohistochemistry in normal calf meniscal tissue and in meniscal cells in 2- and 3-dimensional culture. Calf meniscus cells were seeded in type I and type II collagen-glycosaminoglycan (GAG) matrices. The diameter of the matrices was measured every 2-3 days. Immunohistochemical staining of the 2-dimensional cultures for alpha-SM actin was performed after 1, 3, and 7 days and the staining of the seeded matrices was at 1, 7, 14, and 21 days. Transmission electron microscopy (TEM) was performed on selected samples. After 3 weeks the seeded type I matrices displayed a significant shrinkage of almost 50% whereas the type II matrix and both types of unseeded controls showed almost no contraction over the same time period. Positive staining for the alpha-SM actin phenotype was seen in 10% of the cells of the normal tissue but was present in all cells seeded in monolayer and in both types of matrices. TEM of representative cell-seeded matrices showed microfilaments approximately 7 nm thick, consistent with the myofibroblast phenotype. This is the first report of alpha-SM actin containing cells in the knee meniscus. The finding that, under certain conditions, meniscal cells can express the myofibroblast phenotype warrants study of their role in meniscal healing and the tissue response to implants to facilitate tissue regeneration.

The mechanism of joint capsule thermal modification in an in-vitro sheep model.

The purpose of this study was to understand the mechanism responsible for joint capsule shrinkage after nonablative laser application in an in-vitro sheep model. Femoropatellar joint capsular tissue specimens harvested from 20 adult sheep were treated with one of three power settings of a holmium:yttrium-aluminum-garnet laser or served as a control. Laser treatment significantly shortened the tissue and decreased tissue stiffness in all three laser groups, whereas failure strength was not altered significantly by laser treatment. Transmission electron microscopic examination showed swollen collagen fibrils and loss of membrane integrity of fibroblasts. A thermometric study revealed nonablative laser energy caused tissue temperature to rise in the range of 64 degrees C to 100 degrees C. Electrophoresis after trypsin digestion of the tissue revealed significant loss of distinct alpha bands of Type I collagen in laser treated samples, whereas alpha bands were present in laser treated tissue without trypsin digestion. The results of this study support the concept that the primary mechanism responsible for the effect of nonablative laser energy is thermal denaturation of collagen in joint capsular tissue associated with unwinding of the triple helical structure of the collagen molecule.

The microanatomy of the rhesus monkey temporomandibular joint.

PURPOSE: The objective of this study was to describe and compare the histology of the rhesus monkey temporomandibular joint (TMJ) with that of the human joint. MATERIALS AND METHODS: Seventeen rhesus monkeys (Macaca mulatta) with an age range from 4 to 11 years were used. Both TMJs of the first animal and the left TMJs of the remaining 16 animals were used for this study. The joint specimens were sectioned sagittally and processed for light and electron microscopic studies. RESULTS: The rhesus monkey TMJ consists of the condylar, glenoid fossa, and articular disc components. The histology of these components is described at the light and electron microscopic level. CONCLUSIONS: The monkey TMJ was found to be anatomically similar to the human joint. It was concluded that the rhesus monkey is one of the most suitable animal models for studies involving the TMJ.

Ablation of bone, cartilage, and facet joint capsule using Ho:YAG laser.

OBJECTIVE: The objective of this study was to determine of the efficiency of holmium:YAG laser for bone ablation, compared to cartilage and soft tissue of the intervertebral foramen of the lumbosacral spine. BACKGROUND DATA: The holmium:YAG (Ho:YAG) laser has been used for ablation of bulging or prolapsed discs and also has the potential for decompression of the nerve root when there is narrowing of the foraminae (foraminoplasty). It is proposed that laser ablation of bone and ligament of the intervertebral foramen for nerve root decompression using the Ho:YAG laser is able to produce sufficient bone ablation without inducing significant thermal necrosis in surrounding tissues due to its short absorption length, which could result in significant clinical advantages. MATERIALS AND METHODS: Experiments were performed on samples of laminar bone, facet joint capsule, and cartilage for quantitative and qualitative determination of the effect of Ho:YAG ablation on tissue mass loss using a range of pulse energies from 0.5 to 1.5 J/P at 15 pulses/sec. RESULTS: The results showed a significant linear correlation between the mass loss and pulse energy, and between the mass loss and radiant exposure. Electron microscopy and histology showed that the Ho:YAG ablation resulted in a very sharp and clear border with little charring. Applying 0.01 k.J of total energy at two different settings (1.5 J/p, high power, and 0.5 J/p, low power) at 15 pulses/sec, the cross-sectional area/mm(2) of the ablated bone was measured, using light microscopy and the Scion Image analysis program. The ablated areas were 2.28 +/- 0.87 and 1.16 +/- 0.43 mm(2) at high and low power, respectively (p = 0.008).