Category:
Ankle, tendon imaging
Introduction/Purpose:
Posterior tibialis tendon is of clinical importance in the development and progression of acquired flatfoot and other midfoot deformity. The ...ability to quantitatively evaluate tendon tissue non-invasively would enable assessment of tendon health status and tracking of recovery from injury. Magnetic resonance diffusion tensor imaging (DTI) has been used to examine tendon tissue organization in healing tendon tissue. However, the relationship of DTI-based measures to tendon mechanical function has not been established. The purpose of this pilot study was to quantitatively evaluate posterior tibialis tendon using DTI and determine the relationship of these parameters to tendon function assessed via ex vivo mechanical testing.
Methods:
Posterior tibialis tendons from individuals undergoing amputation were positioned vertically in an agarose mold filled with saline for imaging. High resolution diffusion imaging parameters were optimized for tendon on a 3 T MRI to acquire 13 6-mm transverse slices covering the length: 1mm2 isotropic resolution, 2 signal averaging, repetition/echo times of 5000/58 ms, diffusion strength of 500s/mm2 with 30 gradient directions, scan time 5 min. Diffusion images had sufficient quality and were corrected for motion and image distortion. DTI parametric maps including fractional anisotropy (FA), mean, axial, and radial diffusivities (MD, AD, and RD; mm2/s) were calculated along with fiber tracking indexes of fiber length (mm) and density. After imaging, specimens were preloaded to 10 Newtons, preconditioned 10 cycles at 6% strain, subjected to stress-relaxation at 6% strain (10 minutes), then loaded to a maximum of 10% strain. Relationships between DTI indexes and mechanical properties (stiffness and hysteresis) were evaluated using Spearman correlation.
Results:
Six individuals (4 male, mean(SD) age: 56(5)years, body mass index: 30(6) kg/m2) were included. Reason for amputation was diabetes-related complications in 5 participants and failed orthopaedic surgery in 1 participant. In DTI (Figure 1A), tendons had a tract length of 11.5(11.3)mm and tract density of 23.9(2.4) per ROI. FA, MD, AD, and RD quantify how freely a water molecule is able to move within the tissue, and the directionality of that movement. Tendons had an FA of 0.26(0.25), MD of 1.25(1.28), AD of 1.54(1.57), and RD of 1.11(1.14). Tract length was positively related to linear stiffness (rho=0.829, p=0.04) and hysteresis at 10% strain (rho=0.886, p=0.019) (Figure 1B-D). AD was positively related to hysteresis at 10% strain (rho=0.812, p=0.05).
Conclusion:
This is the first study to describe posterior tibialis tendon appearance on DTI. Tract length and AD are both related to tendon mechanics. Tract length is based on quantity and directionality of water displacement and may indicate degree of collagen organization given its relationship to stiffness. Tract length and AD related positively to hysteresis, which will require additional research to identify the mechanisms behind this relationship. This study is limited by sample size and specimens that likely do not represent healthy tissue. Regardless, these findings support continued investigation into in vivo imaging of tendon with DTI for quantitative tendon assessment.
Category:
Sports
Introduction/Purpose:
The Achilles tendon is one of the most commonly ruptured tendons in the adult population, and there is still no consensus on optimal treatment. While surgical ...repair may result in a lower re-rupture rate and quicker functional return, it also comes with risk of wound complications and sural nerve injury. If surgical repair is chosen, the surgeon may choose a traditional open procedure, a mini-open technique, or a percutaneous approach. The main advantage of the mini open repair method is the reduced wound complications that comes with a much smaller incision, while still maintaining similar re-rupture rates. The purpose of this study was to determine the relationship of the sural nerve to the Arthrex PARS jig and repair sutures.
Methods:
Cadaveric dissection was performed on 10 unpaired above knee amputation specimens. After severing the Achilles tendon and inserting the jig for a mini open repair, the sural nerve was dissected out to determine the rate of nerve puncture by the passed sutures. The jig was then removed to determine if the nerve was bound by the passing sutures or wrapped during suture locking.
Results:
The sural nerve was punctured 9 times out of the total of 50 sutures passed for an 18% puncture rate. All 9 punctures occurred in 4 specimens (Image 1), with the remaining 6 cadavers sustaining no punctures. Of the 6 unpunctured cadavers, 5 had all sutures passing anterior to the sural nerve, but in close proximity. One cadaver had all sutures passing posterior to the sural nerve. In all cadavers, removal of the jig and locking of the sutures left the sural nerve free with the sutures well fixed within the Achilles tendon. The sural nerve was also found to be within 1 cm of the lateral edge of the mini-open transverse incision in all cadavers.
Conclusion:
The Arthrex PARS jig was successful in preventing binding of the sural nerve during mini-open Achilles repair, but the sutures are often passed directly through the nerve during the procedure. The sural nerve is also at risk at the lateral edge of the mini-open incision used to insert the jig, and must be carefully protected during dissection down to the tendon.
Biologics for tendon repair Docheva, Denitsa; Müller, Sebastian A.; Majewski, Martin ...
Advanced drug delivery reviews,
04/2015, Letnik:
84
Journal Article
Recenzirano
Odprti dostop
Tendon injuries are common and present a clinical challenge to orthopedic surgery mainly because these injuries often respond poorly to treatment and require prolonged rehabilitation. Therapeutic ...options used to repair ruptured tendons have consisted of suture, autografts, allografts, and synthetic prostheses. To date, none of these alternatives has provided a successful long-term solution, and often the restored tendons do not recover their complete strength and functionality. Unfortunately, our understanding of tendon biology lags far behind that of other musculoskeletal tissues, thus impeding the development of new treatment options for tendon conditions. Hence, in this review, after introducing the clinical significance of tendon diseases and the present understanding of tendon biology, we describe and critically assess the current strategies for enhancing tendon repair by biological means. These consist mainly of applying growth factors, stem cells, natural biomaterials and genes, alone or in combination, to the site of tendon damage. A deeper understanding of how tendon tissue and cells operate, combined with practical applications of modern molecular and cellular tools could provide the long awaited breakthrough in designing effective tendon-specific therapeutics and overall improvement of tendon disease management.
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The aim of this study was to provide a comprehensive overview of the anatomical, histological, and biomechanical aspects of the Achilles tendon.
A comprehensive search on the relevant aspects of the ...Achilles tendon was performed through the main electronic databases up to October 2019. Data from relevant articles was gathered, analyzed, and included in this review.
This review outlines crucial topics on the anatomy, histology, and biomechanics of the Achilles tendon. The first part, focusing on clinically relevant anatomy, describes the tendon as well as its surrounding structures. Particular focus is made on anatomical divisions. The second part discusses histologic features, contrasting normal morphology with pathologic changes. The third part summarizes various biomechanical aspects of the Achilles tendon, especially those crucial to understanding the key functionality of the tendon. These components make up this review aimed to aggregate relevant information regarding the Achilles tendon to provide an up to date assessment of current knowledge, as well as visions for future directions of Achilles tendon research.
Comprehensive knowledge regarding the Achilles tendon is crucial whilst rates of injury continue to be relevant. A proper understanding of the anatomy, histology, and biomechanics is vital for clinical perception as well as establishing the direction of further research in new therapies.
Tendons that connect muscles to bone are often the targets of sports injuries. The currently unsatisfactory state of tendon repair is largely attributable to the limited understanding of basic tendon ...biology. A number of tendon lineage-related transcription factors have recently been uncovered and provide clues for the better understanding of tendon development. Scleraxis and Mohawk have been identified as critical transcription factors in tendon development and differentiation. Other transcription factors, such as Sox9 and Egr1/2, have also been recently reported to be involved in tendon development. However, the molecular mechanisms and application of these transcription factors remain largely unclear and this prohibits their use in tendon therapy. Here, we systematically review and analyze recent findings and our own data concerning tendon transcription factors and tendon regeneration. Based on these findings, we provide interaction and temporal programming maps of transcription factors, as a basis for future tendon therapy. Finally, we discuss future directions for tendon regeneration with differentiation and trans-differentiation approaches based on transcription factors.
Recent investigation of human tissue and cells from positional tendons such as the rotator cuff has clarified the importance of inflammation in the development and progression of tendon disease. ...These mechanisms remain poorly understood in disease of energy-storing tendons such as the Achilles. Using tissue biopsies from patients, we investigated if inflammation is a feature of Achilles tendinopathy and rupture.
We studied Achilles tendon biopsies from symptomatic patients with either mid-portion tendinopathy or rupture for evidence of abnormal inflammatory signatures. Tendon-derived stromal cells from healthy hamstring and diseased Achilles were cultured to determine the effects of cytokine treatment on expression of inflammatory markers.
Tendinopathic and ruptured Achilles highly expressed CD14+ and CD68+ cells and showed a complex inflammation signature, involving NF-κB, interferon and STAT-6 activation pathways. Interferon markers IRF1 and IRF5 were highly expressed in tendinopathic samples. Achilles ruptures showed increased
and
expression. Tendinopathic and ruptured Achilles tissues expressed stromal fibroblast activation markers podoplanin and CD106. Tendon cells isolated from diseased Achilles showed increased expression of pro-inflammatory and stromal fibroblast activation markers after cytokine stimulation compared with healthy hamstring tendon cells.
Tissue and cells derived from tendinopathic and ruptured Achilles tendons show evidence of chronic (non-resolving) inflammation. The energy-storing Achilles shares common cellular and molecular inflammatory mechanisms with functionally distinct rotator cuff positional tendons. Differences seen in the profile of ruptured Achilles are likely to be attributable to a superimposed phase of acute inflammation and neo-vascularisation. Strategies that target chronic inflammation are of potential therapeutic benefit for patients with Achilles tendon disease.
Mohawk (Mkx) is a member of the Three Amino acid Loop Extension superclass of atypical homeobox genes that is expressed in developing tendons. To investigate the in vivo functions of Mkx, we ...generated Mkx⁻/⁻ mice. These mice had hypoplastic tendons throughout the body. Despite the reduction in tendon mass, the cell number in tail tendon fiber bundles was similar between wild-type and Mkx⁻/⁻ mice. We also observed small collagen fibril diameters and a down-regulation of type I collagen in Mkx⁻/⁻ tendons. These data indicate that Mkx plays a critical role in tendon differentiation by regulating type I collagen production in tendon cells.
Tendon is a crucial component of the musculoskeletal system. Tendons connect muscle to bone and transmit forces to produce motion. Chronic and acute tendon injuries are very common and result in ...considerable pain and disability. The management of tendon injuries remains a challenge for clinicians. Effective treatments for tendon injuries are lacking because the understanding of tendon biology lags behind that of the other components of the musculoskeletal system. Animal and cellular models have been developed to study tendon-cell differentiation and tendon repair following injury. These studies have highlighted specific growth factors and transcription factors involved in tenogenesis during developmental and repair processes. Mechanical factors also seem to be essential for tendon development, homeostasis and repair. Mechanical signals are transduced via molecular signalling pathways that trigger adaptive responses in the tendon. Understanding the links between the mechanical and biological parameters involved in tendon development, homeostasis and repair is prerequisite for the identification of effective treatments for chronic and acute tendon injuries.
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