The effect of biceps reattachment site Schmidt, Christopher C., MD; Weir, David M., MS; Wong, Andrew S., MD ...
Journal of shoulder and elbow surgery,
12/2010, Letnik:
19, Številka:
8
Journal Article
Recenzirano
Background We hypothesize that an anatomic repair of the distal biceps tendon would recreate native tendon moment arm and forearm rotation, while a nonanatomic insertion would compromise moment arm ...and forearm rotation. Methods Isometric supination torque was measured at 60° of pronation, neutral, and 60° of supination for the native distal biceps tendon and 4 repair points in 6 cadaveric specimens using a computer controlled elbow simulator. The slope of the regression line fitted to the torque versus biceps load data was used to define the moment arm for each attachment location. Range of motion testing was performed by incrementally loading the biceps, while measuring the supination motion generated using a digital goniometer. Results Tendon location and forearm position significantly affected the moment arm of the biceps ( P < .05). Anatomic repair in all forearm positions showed no significant difference from the native insertion. Moment arm for an anterior center repair was significantly lower in supination (-97%) and neutral (-27%) and also produced significantly less supination motion. No difference was observed between all tendon locations in pronation. Conclusions Reattachment of the biceps to its anatomic location, as opposed to a more anterior central position, is critical in reestablishing native tendon biomechanics. Clinically, these findings would suggest that patients with a biceps repair might experience the most weakness in a supinated position without experiencing a deficit in the pronated forearm.
Background:
There are several anatomic variations of the peroneal muscles and lateral malleolus of the ankle that may play an important role in the onset of peroneal tendon dislocation.
Purpose:
To ...investigate the anatomic variations of the retromalleolar groove and peroneal muscles in patients with and without recurrent peroneal tendon dislocation using magnetic resonance imaging (MRI) and computed tomography (CT).
Study Design:
Cross-sectional study; Level of evidence, 3.
Methods:
A total of 30 patients (30 ankles) with recurrent peroneal tendon dislocation who underwent both MRI and CT before surgery (PD group) and 30 age- and sex-matched patients (control CN group) who underwent MRI and CT were included in this study. The imaging was reviewed at the level of the tibial plafond (TP level) and at the center slice between the TP and the fibular tip (CS level). The appearance of a malleolar groove (convex, concave, or flat) and the posterior tilting angle of the fibula were assessed on CT images. The appearance of accessory peroneal muscles, height of the peroneus brevis muscle belly, and volume of the peroneal muscle and tendons were assessed on MRI scans.
Results:
There were no differences in the appearance of the malleolar groove, posterior tilting angle of the fibula, or accessory peroneal muscles at the TP and CS levels between the PD and CN groups. The peroneal muscle ratio was significantly higher in the PD group than in the CN group at the TP and CS levels (both P < .001). The height of the peroneus brevis muscle belly was significantly lower in the PD group than in the CN group (P = .001).
Conclusion:
A low-lying muscle belly of the peroneus brevis and a larger muscle volume in the retromalleolar space were significantly associated with peroneal tendon dislocation. Retromalleolar bony morphology was not associated with peroneal tendon dislocation.
The contractile elements in skeletal muscle fibers operate in series with elastic elements, tendons and potentially aponeuroses, in muscle–tendon units (MTUs). Elastic strain energy (ESE), arising ...from either work done by muscle fibers or the energy of the body, can be stored in these series elastic elements (SEEs). MTUs vary considerably in their design in terms of the relative lengths and stiffnesses of the muscle fibers and SEEs, and the force and work generating capacities of the muscle fibers. However, within an MTU it is thought that contractile and series elastic elements can be matched or tuned to maximize ESE storage. The use of ESE is thought to improve locomotor performance by enhancing contractile element power during activities such as jumping, attenuating contractile element power during activities such as landing, and reducing the metabolic cost of movement during steady-state activities such as walking and running. The effectiveness of MTUs in these potential roles is contingent on factors such as the source of mechanical energy, the control of the flow of energy, and characteristics of SEE recoil. Hence, we suggest that MTUs specialized for ESE storage may vary considerably in the structural, mechanical, and physiological properties of their components depending on their functional role and required versatility.
Muscle force production occurs within an environment of tissues that exhibit spring-like behavior, and this elasticity is a critical determinant of muscle performance during locomotion. Muscle force ...and power output both depend on the speed of contraction, as described by the isotonic force-velocity curve. By influencing the speed of contractile elements, elastic structures can have a profound effect on muscle force, power and work. In very rapid movements, elastic mechanisms can amplify muscle power by storing the work of muscle contraction slowly and releasing it rapidly. When energy must be dissipated rapidly, such as in landing from a jump, energy stored rapidly in elastic elements can be released more slowly to stretch muscle contractile elements, reducing the power input to muscle and possibly protecting it from damage. Elastic mechanisms identified so far rely primarily on in-series tendons, but many structures within muscles exhibit spring-like properties. Actomyosin cross-bridges, actin and myosin filaments, titin, and the connective tissue scaffolding of the extracellular matrix all have the potential to store and recover elastic energy during muscle contraction. The potential contribution of these elements can be assessed from their stiffness and estimates of the strain they undergo during muscle function. Such calculations provide boundaries for the possible roles these springs might play in locomotion, and may help to direct future studies of the uses of elastic elements in muscle.
We generated a novel tetracycline-inducible transgenic mouse line with the tendon-specific expression of a series of tendon-critical transcription factors. Primary tenocytes derived from this mouse ...line consistently expressed green fluorescent protein reporter transcription factors in response to doxycycline. The tenocytes maintained their tendon cell properties for a longer time after the transient induction in the absence of growth factors and mechanical stress. Four key transcription factors for tendon development and the green fluorescent protein reporter were linked with different viral 2A self-cleaving peptides. They were expressed under the control of the tet-responsive element. In combination with the expression of BFP, which reports on the tendon-specific collagen I, and mScarlet, which reports on the tendon-specific transcription factor Scleraxis (Scx), we observed the more extended maintenance of the tendon cell identity of in vitro cultured tendon cells and Achilles tendon explants. This means that the Scleraxis bHLH transcription factor (Scx), mohawk homeobox (Mkx), early growth response 1 (Egr1) and early growth response 2 (Egr2) contributed to the maintenance of tenocytes' identity in vitro, providing a new model for studying extracellular matrix alterations and identifying alternative biomaterials in vitro.
Introduction
Hip abductor tendinopathies are becoming increasingly recognized as clinically relevant disorders. However, knowledge about prevalence of abductor tendinopathies and associated disorders ...of adjacent hip articular and periarticular structures is limited. In this context, the relative diagnostic value of 1.5-T vs. 3.0-T MRI magnets has not been studied yet.
Materials and methods
Pelvic MRI scans of 1000 hips from 500 consecutive unselected patients (341 in 3.0-T/159 in 1.5-T magnets, with standardized scanning protocols over the entire study period) were analysed for the detection of abductor tendinosis, calcifying tendinitis, partial or full-thickness tears of the M. gluteus medius (GMed) and/or -minimus (GMin) and trochanteric bursitis (TB). The occurrence of these lesions was correlated to the presence of muscle atrophy (MA) of GMed/GMin, hip joint effusion (JE) and osteoarthritis (OA).
Results
Peritrochanteric lesions were observed with a prevalence of 31.4% of all patients (22.3% of all hips). TB occurred almost exclusively in the presence of GMed/GMin tendinopathies. Compared to overall prevalence, patients with MA displayed lesions of GMed/GMin or TB in 70%, patients, with OA in 30% and with JE in 23%. These lesions occurred significantly more often ipsilateral to MA and OA than contralateral (MA: 76.8% vs. 23.2%,
p
< 0.001; OA: 64.4% vs. 35.6%,
p
= 0.03; JE: 62.7% vs. 37.3%,
p
= 0.08). Significantly more tendon lesions, in particular specific radiological diagnoses like partial/full-thickness tears, were detected by 3.0-T MRI than by 1.5 T (
p
= 0.019).
Conclusions
Peritrochanteric lesions are a prevalent pathology that should specifically be looked for, preferably by 3.0-T MRI, independent of concomitant hip joint pathology.
Management of Anterior Tibialis Tendon Ruptures Chen, Jie; Kadakia, Rishin; Akoh, Craig Chike ...
Journal of the American Academy of Orthopaedic Surgeons,
2021-Aug-15, Letnik:
29, Številka:
16
Journal Article
Recenzirano
Anterior tibialis tendon ruptures, while relatively infrequent ruptures, are commonly identified in delayed fashion, which can lead to significant impairments in patient gait and function. Surgical ...treatment is typically required to restore ankle dorsiflexion function and proper gait. Depending on various patient-specific factors, tendon quality and excursion, and chronicity, a range of treatment options are available to manage these patients, from nonsurgical care to surgical treatment. Surgical options include direct repair, local tendon transfer, autograft tendon reconstruction, and allograft tendon reconstruction. Additional procedures may need to be considered. Despite the variety of described surgical procedures, limited evidence-based guidelines are available to direct surgeons in the most optimal treatment for their patients. In addition to the relevant anatomy, biomechanics, and pathoanatomy, the reconstructive armamentarium is detailed and reviewed here, along with outcomes and potential complications, to guide surgeons in the most appropriate treatment for their patients.
Tendon lesions are common sporting injuries in humans and horses alike. The healing process of acute tendon lesions frequently results in fibrosis and chronic disease. In horses, local mesenchymal ...stromal cell (MSC) injection is an accepted therapeutic strategy with positive influence on acute lesions. Concerning the use of MSCs in chronic tendon disease, data are scarce but suggest less therapeutic benefit. However, it has been shown that MSCs can have a positive effect on fibrotic tissue. Therefore, we aimed to elucidate the interplay of MSCs and healthy or chronically diseased tendon matrix. Equine MSCs were cultured either as cell aggregates or on scaffolds from healthy or diseased equine tendons. Higher expression of tendon-related matrix genes and tissue inhibitors of metalloproteinases (TIMPs) was found in aggregate cultures. However, the tenogenic transcription factor scleraxis was upregulated on healthy and diseased tendon scaffolds. Matrix metalloproteinase (MMPs) expression and activity were highest in healthy scaffold cultures but showed a strong transient decrease in diseased scaffold cultures. The release of glycosaminoglycan and collagen was also higher in scaffold cultures, even more so in those with tendon disease. This study points to an early suppression of MSC matrix remodeling activity by diseased tendon matrix, while tenogenic differentiation remained unaffected.
Mechanical forces between cells and extracellular matrix (ECM) influence cell shape and function. Tendons are ECM-rich tissues connecting muscles with bones that bear extreme tensional force. ...Analysis of transgenic zebrafish expressing mCherry driven by the tendon determinant
reveals that tendon fibroblasts (tenocytes) extend arrays of microtubule-rich projections at the onset of muscle contraction. In the trunk, these form a dense curtain along the myotendinous junctions at somite boundaries, perpendicular to myofibers, suggesting a role as force sensors to control ECM production and tendon strength. Paralysis or destabilization of microtubules reduces projection length and surrounding ECM, both of which are rescued by muscle stimulation. Paralysis also reduces SMAD3 phosphorylation in tenocytes and chemical inhibition of TGFβ signaling shortens tenocyte projections. These results suggest that TGFβ, released in response to force, acts on tenocytes to alter their morphology and ECM production, revealing a feedback mechanism by which tendons adapt to tension.
Advancing age is a well‐known risk factor for tendon disease. Energy‐storing tendons e.g., human Achilles, equine superficial digital flexor tendon (SDFT) are particularly vulnerable and it is ...thought that injury occurs following an accumulation of micro‐damage in the extracellular matrix (ECM). Several authors suggest that age‐related micro‐damage accumulates due to a failure of the aging cell population to maintain the ECM or an imbalance between anabolic and catabolic pathways. We hypothesized that ageing results in a decreased ability of tendon cells to synthesize matrix components and matrix‐degrading enzymes, resulting in a reduced turnover of the ECM and a decreased ability to repair micro‐damage. The SDFT was collected from horses aged 3–30 years with no signs of tendon injury. Cell synthetic and degradative ability was assessed at the mRNA and protein levels. Telomere length was measured as an additional marker of cell ageing. There was no decrease in cellularity or relative telomere length with increasing age, and no decline in mRNA or protein levels for matrix proteins or degradative enzymes. The results suggest that the mechanism for age‐related tendon deterioration is not due to reduced cellularity or a loss of synthetic functionality and that alternative mechanisms should be considered.
PDF
