Gastrocnemius Tendon Research Articles

The Kaplan Fibers of the Iliotibial Band Can Be Identified on Routine Knee Magnetic Resonance Imaging

Background: The Kaplan fibers (KFs) of the iliotibial band have been suggested to play a role in anterolateral rotational instability of the knee, particularly in the setting of an anterior cruciate ligament (ACL) rupture. Description of the normal magnetic resonance imaging (MRI) anatomy of the KFs may facilitate subsequent investigation into the MRI signs of injury. Purpose: To assess if the KF complex can be identified on 3-T MRI using standard knee protocols. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: 3-T MRI scans of 50 ACL-intact knees were reviewed independently by a musculoskeletal radiologist and 2 orthopaedic surgeons. Identification of the KFs was based on radiological diagnostic criteria developed a priori. Identification of the KFs in the sagittal, coronal, and axial planes was recorded. Interobserver reliability was assessed using the Kappa statistic. Detailed anatomy including distance to the joint line and relationship to adjacent structures was recorded. Results: The mean patient age was 43 years (range, 15-81 years), 58% were male, and 50% were right knees. The KFs were identified by at least 2 reviewers on the sagittal images in 96% of cases, on the axial images in 76% of cases, and on the coronal images in 4% of cases. The mean distance from the KF distal femoral insertion to the lateral joint line was 50.1 mm (SD, 6.6 mm) and the mean distance to the lateral gastrocnemius tendon origin was 10.8 mm (SD, 8.6 mm). The KFs were consistently identified immediately anterior to the superior lateral geniculate artery on sagittal imaging. Interobserver reliability for identification was best in the sagittal plane (Kappa 0.5) and worst in the coronal plane (Kappa 0.1). Conclusion: The KF complex can be identified on routine MRI sequences in the ACL-intact knee; however, there is low to moderate interobserver reliability. Imaging in the sagittal plane had the highest rate of identification and the coronal plane the lowest. There is a consistent relationship between the most distal KF femoral attachment and the lateral joint line, lateral gastrocnemius tendon, and superior lateral geniculate artery.

Case of focal dystrophic calcification in the peritarsal soft tissues of a horse

A 12-year-old Irish sports horse gelding presented with a recently developed oval firm mass at the plantaromedial aspect of right tarsus, located between the gastrocnemius and deep digital flexor tendon....

Anatomy and histology of the rabbit common calcanean tendon.

Despite the great progress in the field of tendon injuries and chronic tendinopathies in recent years, treatment of these conditions is still challenging. Research utilising animal models is crucial for further advancement in tendon research, with the rabbit being a commonly used species in this field. The objective of the present study was to comprehensively describe the macro- and microanatomy of the common calcanean tendon (tendo Achillei), together with associated structures. Eight female New Zealand rabbits were subjected to anatomical dissection and histologic analysis, revealing significant species-specific features. The soleus muscle presented a thin, spindle shape with no tendon of insertion and attached directly to the lateral gastrocnemius muscle. Therefore, it does not contribute to the formation of the common calcanean tendon. The calcaneal tendon of the semitendinosus muscle was identified as a strong tendinous band at the medial side of the medial gastrocnemius muscle and the superficial digital flexor muscle and tendon distally. The saphenous artery was accompanied by the medial saphenous vein and characteristic accessory medial saphenous vein. The complex structure of the paratendinous connective tissue is described, with the paratenon being contiguous with the epitenon of the individual tendons and epimysium of associated muscles. At the level of the calcaneal tuber, the retromalleolar fat pad was identified, adhering to the cranial surface of the conjoint gastrocnemius tendon. Histologic studies confirmed the presence of the subtendinous calcaneal bursa of superficial digital flexor tendon and the bursa of calcaneal tendon.

Proximal Ultrasound-Guided Gastrocnemius Recession: A New Ultra-Minimally Invasive Surgical Technique

Selective proximal recession of the medial gastrocnemius head has clear advantages over other approaches and can be performed as a single or combined open procedure for many indications. The purpose of this study was to evaluate the safety and efficacy of a new technique based on ultrasound-guided ultraminimally invasive proximal gastrocnemius recession. We performed a pilot study with 16 cadavers to ensure that the technique was effective and safe; we then prospectively performed gastrocnemius recession in 12 patients (23 cases) with gastrocnemius contracture associated with other indications. We evaluated pre- and postprocedure dorsiflexion, clinical outcomes (based on the visual analog scale and American Orthopedic Foot and Ankle Society scores), and potential complications. We achieved effective release of the proximal medial gastrocnemius tendon in all cases, with no damage to other tissue. Ankle dorsiflexion increased 12° (range 6° to 18°) (p = .05) and was maintained throughout follow-up. The mean preoperative visual analog scale score was 7 (range 5 to 9), which improved to 1 (range 0 to 2) (p = .01). The American Orthopedic Foot and Ankle Society Ankle-Hindfoot Score improved from a mean of 25 (range 20 to 40) to 85 (range 80 to 100) at 6 months and 90 at 12 months (p = .01). No major complications were observed. We considered the technique to be safe and effective for ultrasound-guided ultraminimally invasive proximal-medial gastrocnemius recession using a 1-mm incision in vivo. This novel technique is an alternative to open techniques, with encouraging results and with the potential advantages of reducing pain and obviating lower limb ischemia and deep anesthesia, thus decreasing complications and contraindications and accelerating recovery, although further studies are required.

The association of passive medial gastrocnemius muscle tendon unit lengthening behaviour with ankle gait pattern in children with cerebral palsy

The association of passive medial gastrocnemius muscle tendon unit lengthening behaviour with ankle gait pattern in children with cerebral palsy

Longtime Neurologic Outcome of Extracorporeal Membrane Oxygenation and Non Extracorporeal Membrane Oxygenation Acute Respiratory Distress Syndrome Survivors.

Neurologic complications following acute respiratory distress syndrome (ARDS) are well described, however, information on the neurologic outcome regarding peripheral nervous system complications in critically ill ARDS patients, especially those who received extracorporeal membrane oxygenation (ECMO) are lacking. In this prospective observational study 28 ARDS patients who survived after ECMO or conventional nonECMO treatment were examined for neurological findings. Nine patients had findings related to cranial nerve innervation, which differed between ECMO and nonECMO patients (p = 0.031). ECMO patients had severely increased patella tendon reflex (PTR) reflex levels (p = 0.027 vs. p = 0.125) as well as gastrocnemius tendon reflex (GTR) (p = 0.041 right, p = 0.149 left) were affected on the right, but not on the left side presumably associated with ECMO cannulation. Paresis (14.3% of patients) was only found in the ECMO group (p = 0.067). Paresthesia was frequent (nonECMO 53.8%, ECMO 62.5%; p = 0.064), in nonECMO most frequently due to initial trauma and polyneuropathy, in the ECMO group mainly due to impairments of N. cutaneus femoris lateralis (4 vs. 0; p = 0.031). Besides well-known central neurologic complications, more subtle complications were detected by thorough clinical examination. These findings are sufficient to hamper activities of daily living and impair quality of life and psychological health and are presumably directly related to ECMO therapy.

Accelerated knee osteoarthritis is associated with pre-radiographic degeneration of the extensor mechanism and cruciate ligaments: data from the Osteoarthritis Initiative

BackgroundTo determine if adults with incident accelerated knee osteoarthritis (KOA) are more likely to have degenerative knee ligaments or tendons compared to individuals with typical or no KOA.MethodsWe identified 3 sex-matched groups among Osteoarthritis Initiative participants who had a knee without radiographic KOA at baseline (Kellgren-Lawrence [KL] < 2): 1) accelerated KOA: at least 1 knee had KL grade ≥ 3 in ≤48 months, 2) typical KOA: at least 1 knee increased in radiographic scoring within 48 months, 3) no KOA: both knees had the same KL grade at baseline and 48 months. We evaluated knee magnetic resonance images up to 2 years before and after a visit when the accelerated or typical KOA criteria were met (index visit). Radiologists reported degenerative signal changes for cruciate and collateral ligaments, and extensor mechanism and proximal gastrocnemius tendons. We used generalized linear mixed models with 2 independent variables: group and time.ResultsStarting at least 2 years before onset, adults with accelerated KOA were twice as likely to have degenerative cruciate ligaments than no KOA (odds ratio = 2.10, 95% CI = 1.18, 3.74). A weaker association (not statistically significant) was detected for adults with accelerated versus typical KOA (OR = 1.72, 95%CI = 0.99, 3.02). Regardless of time, adults with accelerated (odds ratio = 2.13) or typical KOA (odds ratio = 2.16) were twice as likely to have a degenerative extensor mechanism than no KOA. No other structural features were statistically significant.ConclusionsDegenerative cruciate ligaments or extensor mechanism antedate radiographic onset of accelerated KOA. Hence, knee instability may precede accelerated KOA, which might help identify patients at high-risk for accelerated KOA and novel prevention strategies.

Atraumatic Calf Swelling In Recreational Cyclist

HISTORY: 51 year-old male presented with intermittent left calf pain and swelling for the past 2 months. The pain and swelling became constant the week preceding his presentation. He had no known injury but first noticed the pain after a spin class 2 months ago. The pain was worse with cycling, jogging, and swimming and at the end of the day. He had no knee pain, ankle pain, or hip pain. He denied lower extremity weakness or numbness. The pain did not radiate. PHYSICAL EXAMINATION: There was a soft tissue enlargement in posterior medial aspect of left calf that was mildly tender to palpation, soft, and non-mobile. Transillumination of the area was positive. No overlying erythema or skin changes were noted. Calf musculature and strength were normal. There was no tenderness along the rest of the gastrocnemius or Achilles tendon and no pretibial edema was present. Neurovascular examination was unremarkable. DIFFERENTIAL DIAGNOSIS: 1. Deep Vein Thrombosis 2. Synovial Cyst 3. Abscess 4. Morel-Lavallée lesion 5. Lipoma 6. Hematoma TESTS AND RESULTS: - Knee x-rays: Grossly normal; generally preserved joint space, with osteophyte formation and mild patellofemoral arthritis - Bedside ultrasound of calf: Large, hypoechoic, cystic appearance; connected with a small stalk to the posterior knee joint capsule (popliteal); no vascularity seen on Color Flow Doppler - Fluid analysis: Yellow, hazy; no crystals seen; minimal nucleated cells FINAL/WORKING DIAGNOSIS: Synovial cyst connected to the popliteal aspect of the knee joint TREATMENT AND OUTCOMES: 1. Bedside ultrasound evaluation 2. Aspiration of popliteal cyst, 85cc of straw-colored fluid, sent for analysis 3. ACE wrap recommended in attempt to prevent re-accumulation of fluid 4. Orthopedic evaluation due to re-accumulation of fluid, recommended continued monitoring given asymptomatic nature 5. Could consider surgical excision if becomes symptomatic

Biologically Inspired Design and Development of a Variable Stiffness Powered Ankle-Foot Prosthesis

Recent advancements in powered lower limb prostheses have appeased several difficulties faced by lower limb amputees by using a series-elastic actuator (SEA) to provide powered sagittal plane flexion. Unfortunately, these devices are currently unable to provide both powered sagittal plane flexion and two degrees of freedom (2-DOF) at the ankle, removing the ankle’s capacity to invert/evert, thus severely limiting terrain adaption capabilities and user comfort. The developed 2-DOF ankle system in this paper allows both powered flexion in the sagittal plane and passive rotation in the frontal plane; an SEA emulates the biomechanics of the gastrocnemius and Achilles tendon for flexion while a novel universal-joint system provides the 2-DOF. Several studies were undertaken to thoroughly characterize the capabilities of the device. Under both level- and sloped-ground conditions, ankle torque and kinematic data were obtained by using force-plates and a motion capture system. The device was found to be fully capable of providing powered sagittal plane motion and torque very close to that of a biological ankle while simultaneously being able to adapt to sloped terrain by undergoing frontal plane motion, thus providing 2-DOF at the ankle. These findings demonstrate that the device presented in this paper poses radical improvements to powered prosthetic ankle-foot device (PAFD) design.

Expression of Collagen Types I, II, IX, and X in the Mineralizing Turkey Gastrocnemius Tendon.

The turkey gastrocnemius tendon mineralizes by intramembranous ossification with a transient chondrogenic phase. The mineralizing zone has hypertrophic chondrocytes similar to endochondral bone formation. These similarities prompted the evaluation of this tendon for the presence of type X collagen in the mineralizing zone. Tendons were removed, radiographed, decalcified, and embedded for frozen sections. Seral sections were H&E stained and immunostained individually with antibodies specific collagens (types I, II, IX, and X). Type I collagen was distributed widely throughout the mineralized tendon extracellular matrix. Types II and IX collagen were at the mineralized/non-mineralized junction. Type X collagen was in the pericellular matrix of hypertrophic chondrocytes and in some calcified matrix. These data support the theory that the gastrocnemius tendon has fibrocartilage characteristics and that type X collagen has a role in the tissue's mineralization. Anat Rec, 2019. © 2019 Wiley Periodicals, Inc.

Correlations between gene expression and mineralization in the avian leg tendon.

Certain avian tendons have been studied previously as a model system for normal mineralization of vertebrates in general. In this regard, the gastrocnemius tendon in the legs of turkeys mineralizes in a well defined temporal and spatial manner such that changes in the initial and subsequent events of mineral formation can be associated with time and specific locations in the tissue. In the present investigation, these parameters and mineral deposition have been correlated with the expression of several genes and the synthesis and secretion of their related extracellular matrix proteins by the composite tenocytes of the tendon. Quantitative polymerase chain reaction analysis demonstrates that mRNA expression of the non-collagenous genes of bone sialoprotein, osteopontin, and osteocalcin corresponds well with the temporal and spatial onset and progression of mineralization. Immunolocalization separately confirms the synthesis and secretion of these matrix molecules. The expression of other non-collagenous genes such as decorin does not show strong correlation with turkey leg tendon mineralization, and expression of vimentin, a cytoskeletal component which may be regulated by biomechanical factors in the tendon, may lead to inhibition of osteocalcin expression during the development and mineralization of the tissue. The overall results of this work provide insight into direct temporal and spatial relations between the genes and proteins of interest as well as the formation and deposition of mineral in the avian tendon model.

Dynamic stretching is not detrimental to neuromechanical and sensorimotor performance of ankle plantarflexors.

The acute effects of two dynamic stretching (DS) protocols on changes in the ankle range of motion (RoM), neuromechanical, and sensorimotor properties of the plantarflexor muscle group were examined. Eighteen participants received slow (SDS) or fast dynamic stretching (FDS) on two separate days. Outcome measures were assessed pre‐ and 2 minutes post‐interventions, and included maximum dorsiflexion angle, maximum isometric torque at neutral ankle position, maximum concentric and eccentric torques, force matching capacity, joint position sense and medial gastrocnemius muscle and tendon strain. Possibly and likely small increases in dorsiflexion RoM were observed after SDS (mean ± 90% confidence intervals; 1.8 ± 1.2°) and FDS (2.1 ± 1.2°), respectively. Very likely moderate decreases in muscle strain after SDS (−38.0 ± 20.6%) and possibly small decrease after FDS (−13.6 ± 21.2%) were observed. SDS resulted in a likely beneficial small increase in tendon strain (25.3 ± 29.7%) and a likely beneficial moderate increase after FDS (41.4 ± 44.9%). Effects on strength were inconsistent. Possibly small effect on positional error after SDS (−27.1 ± 37.5%), but no clear effect after FDS was observed. Both DS protocols increased RoM, and this was more due to an increase in tendon elongation rather than the muscle. However, SDS showed greater improvement than FDS in both neuromechanical and sensorimotor performance, and hence, SDS can be recommended as part of warm‐up in sporting contexts.

Medial Gastrocnemius Muscle–Tendon Junction and Fascicle Lengthening across the Range of Motion Analyzed in 2-D and 3-D Ultrasound Images

Ultrasound imaging modalities offer a clinically viable method to visualize musculoskeletal structures. However, proper data comparison between investigations is compromised because of a lack of measurement error documentation and method standardization. This investigation analyzes the reliability and validity of extracting medial gastrocnemius belly and fascicle lengths and pennation angles in different ankle joint positions, across the full range of motion, in a cohort of 11 children with spastic cerebral palsy and 11 typically developed children. Each of these parameters was extracted from two consecutive acquisitions, using both 2-D and 3-D ultrasound images. The findings suggest that the muscle tendon junction extraction in 2-D images can be a suitable parameter for analyzing medial gastrocnemius muscle length in typically developed children and children with spastic cerebral palsy, although averaging over multiple measurements is recommended to reduce variability. More caution should be taken when performing analyses based on fascicle length.

Off the Courts: Occupational “Tennis Leg”

Injury to the gastrocnemius muscle (tennis leg) is a presenting complaint often associated with athletic pursuits. Despite that label, this form of injury is likely to be common to a variety of salaried and nonsalaried pursuits beyond sports. We describe the presentation and management of two cases of "tennis leg" injury occurring in an occupational rather than athletic setting and review the relevant medical literature. Partial tears of the medial insertion of the gastrocnemius tendon were documented in both cases, in the first through magnetic resonance imaging and in the second by ultrasound. Rupture of the tendon to the medial head of the gastrocnemius, the so-called "tennis leg" injury, should be considered as potentially work-related trauma, rather than taken to be solely a sports injury.

Fabella Syndrome Following De-Rotation Surgery to Correct a Femoral Malunion

Background:The fabella is a sesamoid bone situated within the lateral head of the gastrocnemius tendon, close to the lateral femoral condyle, and adjoined to the fabellofibular ligament. It is a normal variant, found in up to 87% of patients. Fabella Syndrome describes traditionally posterolateral knee pain, occurring due to biomechanical pressure of the fabella against the lateral femoral condyle. Given its rarity, its diagnosis is often overlooked. We present a case of Fabella Syndrome with a modified surgical excision technique and review of the literature.Methods and Results:A thirty-four-year-old man presented with posterolateral knee pain following de-rotation surgery to correct a femoral malunion, from a previous femoral shaft fracture. Due to the patient’s complex orthopaedic history, Fabella Syndrome was not initially diagnosed. Fabellectomy eliminated all symptoms of knee pain, with no limitations in knee function.Conclusion:Review of the literature identified ten publications (evidence level IV) describing Fabella Syndrome. This is the first reported case of Fabella Syndrome secondary to femoral de-rotation surgery. The authors recommend fabellectomy as a definitive treatment for Fabella Syndrome, in keeping with published literature.

Musculotendon excursion potential, tendon slack and muscle fibre length: the interaction of the canine gastrocnemius muscle and tendon.

Although the form-function relation of muscles and tendons has been studied extensively, little invivo data exist on the musculotendon properties of the gastrocnemius complex in dogs. Using a combination of ultrasound and 3D motion tracking, musculotendon parameters were obtained invivo from the lateral gastrocnemius muscle and the gastrocnemius tendon in nine healthy Labrador Retrievers. These parameters include musculotendon length and excursion potential, tendon slack length, muscle belly length, muscle fibre length, pennation angle and architectural index. This study also examined the variation of muscle and tendon length contributions to musculotendon length, as well as the relation between musculotendon excursion potential and muscle fibre length or tendon length. To facilitate comparison between dog breeds, the femur length as a potential scaling parameter was examined. In the Labrador gastrocnemius musculotendon complex, the tendon contributes 41% (±9%) of musculotendon length. In longer musculotendon complexes, the contribution of the muscle belly increases while the tendon contribution decreases. Longer muscle belly and musculotendon complexes were, however, associated with shorter muscle fibres. No significant relations were found between musculotendon excursion potential and muscle fibre length or tendon slack length, and femur length did not prove to be a reliable scale factor for the length-related musculotendon parameters examined in this study. Longer musculotendon complexes exhibit relatively longer muscle bellies, which are in turn associated with shorter muscle fibre lengths. This trade-off between gastrocnemius muscle belly length and muscle fibre length might have the advantage that muscle volume stays constant regardless of the length of the limbs.

Use of Autogenous Fascia Lata Graft in the Treatment of Chronic Segmental Defect of the Common Calcaneus Tendon in Domestic Feline

Background: The common calcaneus tendon is formed by the common tendon of the femoral biceps muscle, tendon of the superficial digital flexor muscle and gastrocnemius muscle tendon, and its rupture is related to acute traumas in small animals. Among some applications described, surgical repair can be adopted in the correction of tendon ruptures and theuse of grafts may be indicated in some severe lesions, where it is not possible to perform tenorrhaphy. This study aims to report the case of a feline with rupture of the common calcaneus tendon in which the tenorrafia associated with the autogenous fascia lata graft was performed as adjuvant to the cicatrization of the same.Case: A 24-month-old, undefined male feline with approximately 3 kg was treated at the FCAV Veterinary Hospital, UNESP Jaboticabal, State of São Paulo, Brazil, with a history of falling, for approximately two weeks, and has since plantigrade posture. Upon physical examination, it was possible to identify a discontinuity of the common calcaneus tendon. The radiographs were performed, which did not show any bone changes. A hemogram and biochemical profile were performed, which were within normal limits. The patient underwent surgery, and a complete lesion of the common calcaneus tendon was identified, with a chronic aspect. Approximation of the stumps was impossible, so a flap of fascia lata, about two centimeters long and one centimeter wide, was removed, which was used as a bed and tendon support for tendon growth. After removal all of the present fibrosis, the tendon stumps were approximated by means of modified Kessler suture with mononylon thread, and fascia lata flap of the ipsilateral limb was sutured with separate single points in both tendon endsand in their lateral and medial portion. In the tibiotarsic joint, the external skeletal fixator type II was used for immobilization, during a period of 30 days. In the immediate postoperative period the patient was already able to support the member on the floor, with progressive improvement, and after 60 days of surgery the animal presented complete support of thelimb, without pain or any other alteration coming from the surgery. The animal presented a rapid recovery after surgical treatment with the autogenous fascia lata flap.Discussion: The rupture of the common calcaneus tendon is not commonly reported in felines and its occurrence is related to acute trauma, where the animals will present lameness and plantigrade posture. Depending on the degree of tendon involvement, there are different procedures that may be indicated, such as tenorrhaphy, reimplantation for avulsion cases, and transplantation with grafts when there is segment loss. In the present study, the use of tenorrhaphy associated with the implantation of autogenous lata-fascia graft was chosen, since the grafts generally provide the framework for healing due to its replacement by collagen tissue in the recipient, in addition to providing mechanical protection initially. Fascia lata, due to its antigenic character as being autogenous, has been shown to be a viable and easily obtained surgical option. The use of the fascia lata graft associated with external immobilization with external fixator type II in the tibiotarsal joint allowed an excellent result and is therefore a recommended treatment for cases of rupture of the common calcaneus tendon in felines.Keywords: cats, lameness, plantigrade stance.

A polygon-shaped complex appearance of medial patellofemoral ligament with dynamic functional insertion based on an outside-in and inside-out dissection technique.

To describe the unclarified characteristics of medial patellofemoral ligament and its relation to neighboring structures. Sixteen fresh-frozen human knees were dissected in using outside-in and inside-out combined technique. The patellar side attachment was observed from the inside view and femoral side from outside view. The medial patellofemoral ligament was described a complex and multiconnected structure. The femoral side included the upper and lower portion, of which the upper portion attached on the femur with mean width 7.5±1.1 mm and its superficial fibers extended to the adductor magnus tendon and the medial gastrocnemius tendon, and of which the lower portion appeared a right-triangle connected to the MCL without bony attachment. From inside view, the patellar attachment consisted of the bony and non-bony parts. The width of bony attachment was measured mean 16.3±3.8mm, and the non-bony attachment was found attached on the vastus intermedius tendon with mean width 21.7±4.8mm. The average thickness was 0.4±0.1mm and the length were inside assessed mean 67.9±6.1mm. The medial patellofemoral ligament which dissected a complicated structure with bony and non-bony attachment and multi-connected to neighboring structures on both patella and femur side appears as a polygon-shaped complex structure.

Between-day reliability of MyotonPRO for the non-invasive measurement of muscle material properties in the lower extremities of patients with a chronic spinal cord injury

Measuring the muscle properties of patients with spinal cord injuries (SCIs) is important to better understand their biomechanical features. In this study, we sought to evaluate the between-day reliability of MyotonPRO, a handheld device that can measure muscle mechanical properties, and assess whether it is reliable to measure muscle properties over time in patients with SCI. Thirteen men with complete SCIs (age 53.9 ± 6.3 years, height 171.0 ± 5.2 cm, weight 66.1 ± 5.8 kg), and injury levels ranging from L1 to T12, were enrolled. Oscillation frequency; logarithmic decrement; dynamic stiffness; mechanical stress relaxation time; and creep of the biceps femoris, medial and lateral gastrocnemius, rectus femoris, tibialis anterior, and Achilles tendon were measured on consecutive days using MyotonPRO. The intraclass coefficient for most muscles and the Achilles tendon ranged from 0.53 to 0.99 for all parameters. The percentage standard error of the measurement for many parameters in most muscles and the Achilles tendon was less than 10%. Bland-Altman analysis showed a high agreement for all mechanical properties. No significant differences were observed in any muscle or Achilles tendon properties between days (all p > 0.05). These results indicate that the MyotonPRO is reliable for between-day measurements of the mechanical properties of lower limb muscles and Achilles tendon in patients with SCI.

Elevated whole muscle phosphatidylcholine: phosphatidylethanolamine ratio coincides with reduced SERCA activity in murine overloaded plantaris muscles

BackgroundAn increase in phosphatidylcholine:phosphatidylethanolamine (PC:PE) and a decrease in fatty acyl chain length, monounsaturated:polyunsaturated (MUFA:PUFA) fatty acyl ratio reduces SERCA activity in liposomes and in mouse models of obesity and muscular dystrophy. We have previously shown that maximal SERCA activity is significantly reduced in mechanically overloaded (OVL) plantaris, however, whether changes in PC:PE ratio or fatty acyl composition may contribute to the alterations in maximal SERCA activity remain unknown. Here, we tested the hypotheses that in OVL plantaris 1) PC:PE ratio would negatively correlate with maximal SERCA activity and 2) PC fatty acyl chain length (ACL) and/or MUFA:PUFA ratio would positively correlate with maximal SERCA activity.MethodsTo overload plantaris in mice, we transected the soleus and gastrocnemius tendons from one leg, while the contralateral leg underwent a sham surgery. After two weeks, plantaris muscles were extracted, homogenized and processed for SERCA activity and lipid analyses. Specifically, we performed HPTLC densitometry to examine changes in PC, PE, and the ratio of PC:PE. We also performed gas chromatography to assess any potential changes to fatty acyl composition.ResultsSERCA activity was significantly reduced in OVL plantaris compared with sham. Coinciding with this, we found a significant increase in PC but not PE in OVL plantaris. In turn, there was an increase in PC:PE but did not reach significance (p = 0.09). However, we found a significant negative correlation between PC:PE and maximal SERCA activity. Fatty acyl composition of PE remained similar between OLV and sham and PC demonstrated higher percent mole fraction of 17:1, 18:1, and ACL compared to sham. In addition, PC ACL, % MUFA, % PUFA, or MUFA:PUFA did not significantly correlate with maximal SERCA activity.ConclusionsOur results indicate that the phospholipid headgroup PC:PE negatively correlated and could potentially contribute to reductions in SERCA activity seen in functionally overloaded plantaris. In contrast, fatty acyl chain (ACL, % MUFA, % PUFA, MUFA:PUFA) did not correlate with maximal SERCA activity. Future studies will determine whether altering PC:PE with genetic and dietary interventions can influence SERCA activity and ultimately change the physiological outcome in response to muscle overloading.