The histochemical structure of the deep fascia and its structural response to surgery

Scoping review and interpretation of myofascial pain/fibromyalgia syndrome: An attempt to assemble a medical puzzle

BACKGROUND

Myofascial Pain Syndrome (MPS) is a common, overlooked, and underdiagnosed condition and has significant burden. MPS is often dismissed by clinicians while patients remain in pain for years. MPS can evolve into fibromyalgia, however, effective treatments for both are lacking due to absence of a clear mechanism. Many studies focus on central sensitization. Therefore, the purpose of this scoping review is to systematically search cross-disciplinary empirical studies of MPS, focusing on mechanical aspects, and suggest an organic mechanism explaining how it might evolve into fibromyalgia. Hopefully, it will advance our understanding of this disease.

METHODS

Systematically searched multiple phrases in MEDLINE, EMBASE, COCHRANE, PEDro, and medRxiv, majority with no time limit. Inclusion/exclusion based on title and abstract, then full text inspection. Additional literature added on relevant side topics. Review follows PRISMA-ScR guidelines. PROSPERO yet to adapt registration for scoping reviews.

FINDINGS

799 records included. Fascia can adapt to various states by reversibly changing biomechanical and physical properties. Trigger points, tension, and pain are a hallmark of MPS. Myofibroblasts play a role in sustained myofascial tension. Tension can propagate in fascia, possibly supporting a tensegrity framework. Movement and mechanical interventions treat and prevent MPS, while living sedentarily predisposes to MPS and recurrence.

CONCLUSIONS

MPS can be seen as a pathological state of imbalance in a natural process; manifesting from the inherent properties of the fascia, triggered by a disrupted biomechanical interplay. MPS might evolve into fibromyalgia through deranged myofibroblasts in connective tissue ("fascial armoring"). Movement is an underemployed requisite in modern lifestyle. Lifestyle is linked to pain and suffering. The mechanism of needling is suggested to be more mechanical than currently thought. A "global percutaneous needle fasciotomy" that respects tensegrity principles may treat MPS/fibromyalgia more effectively. "Functional-somatic syndromes" can be seen as one entity (myofibroblast-generated-tensegrity-tension), sharing a common rheuma-psycho-neurological mechanism.

Anatomical basis of fascial plane blocks

Fascial plane blocks (FPBs) are regional anesthesia techniques in which the space ("plane") between two discrete fascial layers is the target of needle insertion and injection. Analgesia is primarily achieved by local anesthetic spread to nerves traveling within this plane and adjacent tissues. This narrative review discusses key fundamental anatomical concepts relevant to FPBs, with a focus on blocks of the torso. Fascia, in this context, refers to any sheet of connective tissue that encloses or separates muscles and internal organs. The basic composition of fascia is a latticework of collagen fibers filled with a hydrated glycosaminoglycan matrix and infiltrated by adipocytes and fibroblasts; fluid can cross this by diffusion but not bulk flow. The plane between fascial layers is filled with a similar fat-glycosaminoglycan matric and provides gliding and cushioning between structures, as well as a pathway for nerves and vessels. The planes between the various muscle layers of the thorax, abdomen, and paraspinal area close to the thoracic paravertebral space and vertebral canal, are popular targets for ultrasound-guided local anesthetic injection. The pertinent musculofascial anatomy of these regions, together with the nerves involved in somatic and visceral innervation, are summarized. This knowledge will aid not only sonographic identification of landmarks and block performance, but also understanding of the potential pathways and barriers for spread of local anesthetic. It is also critical as the basis for further exploration and refinement of FPBs, with an emphasis on improving their clinical utility, efficacy, and safety.

Hyaluronan and the Fascial Frontier

The buzz about hyaluronan (HA) is real. Whether found in face cream to increase water volume loss and viscoelasticity or injected into the knee to restore the properties of synovial fluid, the impact of HA can be recognized in many disciplines from dermatology to orthopedics. HA is the most abundant polysaccharide of the extracellular matrix of connective tissues. HA can impact cell behavior in specific ways by binding cellular HA receptors, which can influence signals that facilitate cell survival, proliferation, adhesion, as well as migration. Characteristics of HA, such as its abundance in a variety of tissues and its responsiveness to chemical, mechanical and hormonal modifications, has made HA an attractive molecule for a wide range of applications. Despite being discovered over 80 years ago, its properties within the world of fascia have only recently received attention. Our fascial system penetrates and envelopes all organs, muscles, bones and nerve fibers, providing the body with a functional structure and an environment that enables all bodily systems to operate in an integrated manner. Recognized interactions between cells and their HA-rich extracellular microenvironment support the importance of studying the relationship between HA and the body’s fascial system. From fasciacytes to chronic pain, this review aims to highlight the connections between HA and fascial health.

A comparative multi-site and whole-body assessment of fascia in the horse and dog: a detailed histological investigation

Fascia in the veterinary sciences is drawing attention, such that physiotherapists and animal practitioners are now applying techniques based on the concept of fascia studies in humans. A comprehensive study of fascia is therefore needed in animals to understand the arrangement of the fascial layers in an unguligrade horse and a digitigrade dog. This study has examined the difference between the horse and the dog fascia at specific regions, in terms of histology, and has compared it with the human model. Histological examinations show that in general the fascia tissue of the horse exhibits a tight and dense composition, while in the dog it is looser and has non-dense structure. Indeed, equine fascia appears to be different from both canine fascia and the human fascia model, whilst canine fascia is very comparable to the human model. Although regional variations were observed, the superficial fascia (fascia superficialis) in the horse was found to be trilaminar in the trunk, yet multilayered in the dog. Moreover, crimping of collagen fibers was more visible in the horse than the dog. Blood vessels and nerves were present in the loose areolar tissue of the superficial and the profound compartment of hypodermis. The deep fascia (fascia profunda) in the horse was thick and tightly attached to the underlying muscle, while in the dog the deep fascia was thin and loosely attached to underlying structures. Superficial and deep fascia fused in the extremities. In conclusion, gross dissection and histology have revealed species variations that are related to the absence or presence of the superficial adipose tissue, the retinacula cutis superficialis, the localization and amount of elastic fibers, as well as the ability to slide and glide between the different layers. Further research is now needed to understand in more detail whether these differences have an influence on the biomechanics, movements and proprioception of these animals.

Educational avenues for promoting dialog on fascia

If your healthcare professional students have not heard about the importance of fascia they definitely should, and if your residents have not heard about the manifestations of fascia health they definitely will from their patients. While fascia may not be the sexiest of organ systems, it is one of the most influential. Fascia is gaining interest from researchers, physicians, and many subdivisions of manual medicine including massage therapists. The fascial system is now being recognized with roles in pathology, fluid movement, and proprioception. It is also important in skeletal muscle movement, perception of pain, protein regulation and expression, cell signaling, neoplastic growth, and hormone distribution in our body. It can be the reason why we feel chronic pain or why we feel tightness after physical activity. The primary responsibility of fascia is to connect systems so that the body works as a whole, which is what permits this topic to be easily embedded anywhere in our health curricula. Whether you teach students in schools of medical, veterinary, dental, physical therapy, physician assistant studies, or occupational therapy, fascia matters. Whether you teach in an integrated curriculum or a curriculum that is designed for problem-based learning or a classical discipline-based curriculum, connective tissue has a place in academia. So, in our cramped curriculum how do we make sure that our current undergraduate and graduate students understand the complexity of fascia without adding additional time to coursework? To answer this question, this article demonstrates how fascia can fit anywhere in the curriculum because it is found everywhere. Clin. Anat. 32:871-876, 2019. © 2019 Wiley Periodicals, Inc.

Quantification of hyaluronan in human fasciae: variations with function and anatomical site

Recently, alterations in fascial gliding-like movement have been invoked as critical in the etiology of myofascial pain. Various methods have been attempted for the relief of this major and debilitating clinical problem. Paramount have been attempts to restore correct gliding between fascial layers and the movement over bone, joint, and muscular structures. One of the key elements that underlies such fascial movement is hyaluronan. However, until now, the precise content of hyaluronan within fasciae has been unknown. This study quantifies for the first time the hyaluronan content of human fascial samples obtained from a variety of anatomic sites. Here, we demonstrate that the average amount varies according to anatomic site, and according to the different kinds of sliding properties of the particular fascia. For example, the fascia lata has 35 μg of hyaluronan per gram of tissue, similar to that of the rectus sheath (29 μg g^-1 ). However, the types of fascia adherent to muscle contain far less hyaluronan: 6 μg g^-1 in the fascia overlying the trapezius and deltoid muscles. In the fascia that surrounds joints, the hyaluronan increases to 90 μg g^-1 , such as in the retinacula of the ankle, where greater degrees of movement occur. Surprisingly, no significant differences were detected at any site as a function of age or sex (P-value > 0.05, t-test) with the sole exception of the plantar fascia. This work can provide a better understanding of the role of hyaluronan in fascia. It will facilitate a better comprehension of the modulation of the hyaluronan-rich layer that occurs in relation to the various conditions that affect fascia, and the diverse factors that underlie the attendant pathologies.

Fascial hierarchies and the relevance of crossed-helical arrangements of collagen to changes in shape; part II: The proposed effect of blood pressure (Traube-Hering-Mayer) waves on the fascia

Periodic changes in arterial pressure and volume have long been related to respiratory and sympathetic nerve activity (Traube-Hering-Mayer waves) but their origins and nomenclature have caused considerable confusion since they were first discovered in the eighteenth century. However, although they remain poorly understood and the underlying details of their control are complicated, these waves do provide valuable clinical information on the state of blood pressure regulation in both normal and pathological conditions; and a correlation with oscillatory motions observed by certain practitioners suggests that they may also have some physiological value that relates to changes in the volume of fascial 'tubes'. Part I of this paper (Scarr, 2016) described a complex fascial network of collagen-reinforced tubular sheaths that are an integral part of muscle structure and function, and continuous with 'higher-level' fascial tubes surrounding groups of muscles, the limbs and entire body. The anisotropic arrangements of collagen fibres within the walls of these tubes reflect the most efficient distribution of mechanical stresses and have been considered to coordinate changes in shape, and a proposed link between cyclic variations in arterial pressure and volume, and the behaviour of these fascial compartments is now described.

A Proximally Based Sural Fasciocutaneous Flap for the Treatment of Recurrent Peroneal Neuropathy: A Case Report

Surgical treatment for recurrent, common peroneal neuropathy has not been reported. Herein, we describe a successfully treated case using the proximally based sural fasciocutaneous flap after reneurolysis of the adhesive common peroneal nerve. A 33-year-old man received a neurolysis operation for entrapment neuropathy of the common peroneal nerve 2 years before first admission in our clinic. Although motor nerve conduction studies showed a marked improvement after the primary operation, the patient always required the use of a crutch because of severe pain radiating to the lower leg during standing or walking. We diagnosed adhesive neuropathy of the common peroneal nerve, and performed reneurolysis by wrapping of the released nerve with a proximally based sural fasciocutaneous flap to prevent readhesion. The radiating pain was significantly reduced at 1-month postoperation. At 1-year postoperation, the patient could walk a long distance without a crutch. Wrapping the released common peroneal nerve with a proximally based sural fasciocutaneous flap is a useful option for the treatment of recurrent, common peroneal neuropathy.

Fascial hierarchies and the relevance of crossed-helical arrangements of collagen to changes in the shape of muscles

Muscles are composite structures consisting of contractile myofibres surrounded by complex hierarchies of collagen-reinforced fascial sheaths. They are essentially flexible cylinders that change in shape, with the particular alignment of collagen fibres within their myofascial walls reflecting the most efficient distribution of mechanical stresses and coordinating these changes. However, while the functional significance of this crossed-helical fibre arrangement is well established in other species and in different parts of the body, relatively little attention has been given to this within the fascia of humans; and the relevance of this geometric configuration to muscles and surrounding fascial tissues is described.

Electron microscopy of human fascia lata: focus on telocytes

From the histological point of view, fascia lata is a dense connective tissue. Although extracellular matrix is certainly the most predominant fascia's feature, there are also several cell populations encountered within this structure. The aim of this study was to describe the existence and characteristics of fascia lata cell populations viewed through a transmission electron microscope. Special emphasis was placed on telocytes as a particular interstitial cell type, recently discovered in a wide variety of tissues and organs such as the heart, skeletal muscles, skin, gastrointestinal tract, uterus and urinary system. The conducted study confirmed the existence of a telocyte population in fascia lata samples. Those cells fulfil main morphological criteria of telocytes, namely, the presence of very long, thin cell processes (telopodes) extending from a relatively small cell body. Aside from telocytes, we have found fibroblasts, mast cells and cells with features of myofibroblastic differentiation. This is the first time it has been shown that telocytes exist in human fascia. Currently, the exact role of those cells within the fascia is unknown and definitely deserves further attention. One can speculate that fascia lata telocytes likewise telocytes in other organs may be involved in regeneration, homeostasis and intracellular signalling.

Viscoelastic Properties of Hyaluronan in Physiological Conditions

Hyaluronan (HA) is a high molecular weight glycosaminoglycan of the extracellular matrix (ECM), which is particularly abundant in soft connective tissues. Solutions of HA can be highly viscous with non-Newtonian flow properties. These properties affect the movement of HA-containing fluid layers within and underlying the deep fascia. Changes in the concentration, molecular weight, or even covalent modification of HA in inflammatory conditions, as well as changes in binding interactions with other macromolecules, can have dramatic effects on the sliding movement of fascia. The high molecular weight and the semi-flexible chain of HA are key factors leading to the high viscosity of dilute solutions, and real HA solutions show additional nonideality and greatly increased viscosity due to mutual macromolecular crowding. The shear rate dependence of the viscosity, and the viscoelasticity of HA solutions, depend on the relaxation time of the molecule, which in turn depends on the HA concentration and molecular weight. Temperature can also have an effect on these properties. High viscosity can additionally affect the lubricating function of HA solutions. Immobility can increase the concentration of HA, increase the viscosity, and reduce lubrication and gliding of the layers of connective tissue and muscle. Over time, these changes can alter both muscle structure and function. Inflammation can further increase the viscosity of HA-containing fluids if the HA is modified via covalent attachment of heavy chains derived from Inter-α-Inhibitor. Hyaluronidase hydrolyzes HA, thus reducing its molecular weight, lowering the viscosity of the extracellular matrix fluid and making outflow easier. It can also disrupt any aggregates or gel-like structures that result from HA being modified. Hyaluronidase is used medically primarily as a dispersion agent, but may also be useful in conditions where altered viscosity of the fascia is desired, such as in the treatment of muscle stiffness.

Mathematical analysis of the flow of hyaluronic acid around fascia during manual therapy motions

CONTEXT

More research is needed to understand the flow characteristics of hyaluronic acid (HA) during motions used in osteopathic manipulative treatment and other manual therapies.

OBJECTIVE

To apply a 3-dimensional mathematical model to explore the relationship between the 3 manual therapy motions (constant sliding, perpendicular vibration, and tangential oscillation) and the flow characteristics of HA below the fascial layer.

METHODS

The Squeeze Film Lubrication theory of fluid mechanics for flow between 2 plates was used, as well as the Navier-Stokes equations.

RESULTS

The fluid pressure of HA increased substantially as fascia was deformed during manual therapies. There was a higher rate of pressure during tangential oscillation and perpendicular vibration than during constant sliding. This variation of pressure caused HA to flow near the edges of the fascial area under manipulation, and this flow resulted in greater lubrication. The pressure generated in the fluid between the muscle and the fascia during osteopathic manipulative treatment causes the fluid gap to increase. Consequently, the thickness between 2 fascial layers increases as well. Thus, the presence of a thicker fluid gap can improve the sliding system and permit the muscles to work more efficiently.

CONCLUSION

The mathematical model employed by the authors suggests that inclusion of perpendicular vibration and tangential oscillation may increase the action of the treatment in the extracellular matrix, providing additional benefits in manual therapies that currently use only constant sliding motions.

Fascial components of the myofascial pain syndrome. Curr Pain Headache Rep. 2013;17:352. [PMID: 23801005 DOI: 10.1007/s11916-013-0352-9]

Myofascial pain syndrome (MPS) is described as the muscle, sensory, motor, and autonomic nervous system symptoms caused by stimulation of myofascial trigger points (MTP). The participation of fascia in this syndrome has often been neglected. Several manual and physical approaches have been proposed to improve myofascial function after traumatic injuries, but the processes that induce pathological modifications of myofascial tissue after trauma remain unclear. Alterations in collagen fiber composition, in fibroblasts or in extracellular matrix composition have been postulated. We summarize here recent developments in the biology of fascia, and in particular, its associated hyaluronan (HA)-rich matrix that address the issue of MPS.

Fascia Research Congress evidence from the 100 year perspective of Andrew Taylor Still

More than 100 years ago A.T. Still MD founded osteopathic medicine, and specifically described fascia as a covering, with common origins of layers of the fascial system despite diverse names for individual parts. Fascia assists gliding and fluid flow and is highly innervated. Fascia is intimately involved with respiration and with nourishment of all cells of the body, including those of disease and cancer. This paper reviews information presented at the first three International Fascia Research Congresses in 2007, 2009 and 2012 from the perspective of Dr Still, that fascia is vital for organism's growth and support, and it is where disease is sown.

Stress and matrix-responsive cytoskeletal remodeling in fibroblasts

In areolar "loose" connective tissue, fibroblasts remodel their cytoskeleton within minutes in response to static stretch resulting in increased cell body cross-sectional area that relaxes the tissue to a lower state of resting tension. It remains unknown whether the loosely arranged collagen matrix, characteristic of areolar connective tissue, is required for this cytoskeletal response to occur. The purpose of this study was to evaluate cytoskeletal remodeling of fibroblasts in, and dissociated from, areolar and dense connective tissue in response to 2 h of static stretch in both native tissue and collagen gels of varying crosslinking. Rheometric testing indicated that the areolar connective tissue had a lower dynamic modulus and was more viscous than the dense connective tissue. In response to stretch, cells within the more compliant areolar connective tissue adopted a large "sheet-like" morphology that was in contrast to the smaller dendritic morphology in the dense connective tissue. By adjusting the in vitro collagen crosslinking, and the resulting dynamic modulus, it was demonstrated that cells dissociated from dense connective tissue are capable of responding when seeded into a compliant matrix, while cells dissociated from areolar connective tissue can lose their ability to respond when their matrix becomes stiffer. This set of experiments indicated stretch-induced fibroblast expansion was dependent on the distinct matrix material properties of areolar connective tissues as opposed to the cells' tissue of origin. These results also suggest that disease and pathological processes with increased crosslinks, such as diabetes and fibrosis, could impair fibroblast responsiveness in connective tissues.

NGF-evoked sensitization of muscle fascia nociceptors in humans

Nerve growth factor (NGF) induces local hyperalgesia for a few days after intramuscular injection, but longer-lasting muscle pain upon systemic administration. As the muscle fascia is densely innervated by free nerve endings, we hypothesized a lasting sensitization of fascia nociceptors by NGF. We administered 1 μg NGF (dissolved in 100 μL saline) ultrasound-guided to the fascia of the Musculus erector spinae muscle at the lumbar level of 14 male volunteers and assessed hypersensitivity after 6 hours, and 1, 3, 7, 14, and 21 days. Pain upon mechanical stimuli (constant pressure and dynamic impact), upon exercise and electrically induced M. erector spinae contraction, and upon injection of 100 μL phosphate buffer pH4 (at day 7 and 14 only) to the fascia of both NGF- and saline-treated muscles, was investigated. Injections into the muscle fascia did not cause acute pain. Local heat pain thresholds were unchanged following NGF and saline (control) administration. NGF evoked a lasting (days 1-7) and significant reduction of pressure pain, pressure thresholds, exercise-evoked muscle pain, and hyperalgesia to impact stimuli (12 m/s). Pain upon injected protons was significantly elevated (P<0.04) for 2 weeks. NGF induced a sensitization of the muscle fascia to mechanical and chemical stimuli lasting for up to 2 weeks. As nociceptors in the fascia appear to be particularly prone to sensitization, they may contribute to acute or chronic muscle pain.

Fascia Research from a Clinician/Scientist's Perspective

The upcoming Third International Fascia Research Congress will have much exciting information for the clinician, as well as for the clinical and basic science researcher. This paper provides a perspective from a clinician/scientist, including the fascial network of body-wide connections between and within individual cells, and sharing of loads between muscle and fascia. Basic studies of fibroblast cell shape show the impact of manual therapy, acupuncture, and yoga-like stretching at the cellular level. Advances in scientific equipment have made it possible to study a layer of hyaluronan fluid, which allows sliding between deep fascia and muscle. Collagen fibers within fascia affect both blood flow to muscles and lymphatic fluid flow.

Hyaluronan within fascia in the etiology of myofascial pain

The layers of loose connective tissue within deep fasciae were studied with particular emphasis on the histochemical distribution of hyaluronan (HA). Samples of deep fascia together with the underlying muscles were taken from neck, abdomen and thigh from three fresh non-embalmed cadavers. Samples were stained with hematoxylin-eosin, Azan-Mallory, Alcian blue and a biotinylated HA-binding protein specific for HA. An ultrasound study was also performed on 22 voluntary subjects to analyze the thickness of these deep fasciae and their sublayers. The deep fascia presented a layer of HA between fascia and the muscle and within the loose connective tissue that divided different fibrous sublayers of the deep fascia. A layer of fibroblast-like cells that stained prominently with Alcian blue stain was observed. It was postulated that these are cells specialized for the biosynthesis of the HA-rich matrix. These cells we have termed "fasciacytes", and may represent a new class of cells not previously recognized. The ultrasound study highlighted a mean thickness of 1.88 mm of the fascia lata, 1.68 mm of the rectus sheath, and 1.73 mm of the sternocleidomastoid fascia. The HA within the deep fascia facilitates the free sliding of two adjacent fibrous fascial layers, thus promoting the normal function associated with the deep fascia. If the HA assumes a more packed conformation, or more generally, if the loose connective tissue inside the fascia alters its density, the behavior of the entire deep fascia and the underlying muscle would be compromised. This, we predict, may be the basis of the common phenomenon known as "myofascial pain."

Detail microscopic analysis of deep fascia of lower limb and its surgical implication

BACKGROUND

The knowledge regarding the structural details of deep fascia remains inadequate. It was described to be relatively avascular having predominantly protective function. Anatomical and surgical studies revealed that it had associated vascular arcade and hence incorporated it to ascertain additional vascularity to the flaps. However, not much importance has been directed towards the detailed study of the various constituents of deep fascia in order to explain its physiological and clinical implications. Therefore, this study was undertaken to unveil these details.

MATERIALS AND METHODS

Fifty fresh specimens of human deep fascia overlying the gastrocnemius muscle were analyzed regarding the (i) vasculature, (ii) matrix, and (iii) other structural elements. The deep fascia was procured in three forms; (a) both the layers, (b) superficial layer, and (c) deep layer. Detail study was conducted by light, confocal, and electron microscopy.

RESULTS

Under light microscopy, blood vessels including capillaries were seen associated with both the layers. Perforators traversing the intra-fascial plane could be visualized. Confocal microscope optical sections showed well-organized bright fluorescent collagen fibers and nuclei of various cells. Electron microscopic evaluation revealed many interesting constituents which are relatively unknown to the anatomist and clinicians. There were arterioles, capillaries, venules, lymphatics, nerves, mast cells, and myofibroblasts apart from collagen and elastic fibers.

CONCLUSION

The detail structural analysis of deep fascia provided the clue to its rich vascularity and other structural constituents. They all contribute to enhance the vascularity and maintenance of the physiological functions of fasciocutaneous, adipofascial, and fascial flaps, frequently used for reconstructions. Thus, incorporation of deep fascia in the flaps during reconstruction is highly beneficial for ensuring optimal vascularity.

Epimysium and perimysium in suturing in skeletal muscle lacerations

BACKGROUND

Direct muscle belly trauma is common. Selecting optimal methods for surgical repair of muscle disruption is difficult because reliable methods have not been established. Suturing tendon offers strong repairs, but epimysium and perimysium, the connective tissues that coalesce to form tendons, offer unknown repair strength. The purpose of this study was to compare biomechanical properties of repaired muscle in transected muscle bellies with epimysium and perimysium.

METHODS

The authors surgically repaired with figure-eight stitches in both epimysium and perimysium groups. Individual stitches were placed in lacerated quadriceps bellies from a euthanized pig and were tensioned on a biomechanical machine. Maximum loads and strains were measured, and failure mechanisms were recorded.

RESULTS

Loads and strains for repairs with epimysium were higher than those for repairs with perimysium. Failure mechanisms were significantly different between groups.

CONCLUSION

These data showed that epimysium incorporation into suturing improves capacity to bear forces compared with perimysium incorporation.

The role of epimysium in suturing skeletal muscle lacerations

BACKGROUND

Direct muscle trauma is a common and disabling clinical problem. Surgical muscle repair is difficult to evaluate because reliable repair techniques have not been established scientifically. The purpose of this study was to assess the biomechanical properties of epimysium, the collagenous tissue sheath that surrounds muscles in the body.

STUDY DESIGN

We surgically repaired transected porcine muscle bellies with and without epimysium. For both groups, 25 figure-eight stitches in lacerated quadriceps bellies from a euthanatized pig were loaded under tension on a biomechanical machine (model 8521S, Instron Company). Maximum loads and strains were measured and mechanisms of failure recorded.

RESULTS

The mean load for repairs with epimysium (25.1 N) was significantly higher (p = 0.034) than that for repairs without epimysium (21.2 N). The mean strain for repairs with epimysium (10.4%) was significantly higher (p < 0.001) than that for repairs without epimysium (7.3%). The mechanisms of failure were also different. Among epimysium repairs, 15 stitches avulsed muscle transversely, and 10 stitches tore out longitudinally from the muscle. In the nonepimysium group, 1 suture avulsed muscle and 24 sutures tore out. Muscle was the weakest element in each test.

CONCLUSIONS

These data showed that epimysium incorporation into suturing improves the capacity of repairs to bear force. These findings fill a knowledge gap and may improve outcomes of muscle suturing. By focusing the experiment on biomechanical properties of muscle stitching, this study showed the key role epimysium plays in muscle suturing.