Gastrocnemius Tendon Research Articles

Age and sex-related differences in elastic properties of the gastrocnemius muscle-tendon unit: an observational prospective study

IntroductionChanges in the mechanical properties of the gastrocnemius muscle-tendon unit can lead to abnormal biomechanics of lower limbs, which is a risk factor for the development of many diseases. However, fewer studies have explored physiological changes in the gastrocnemius muscle-tendon unit stiffness. This study aimed to investigate the age- and sex-related differences in the gastrocnemius muscle-tendon unit stiffness.MethodsThe study included 20 older women, 20 young women, and 20 older men. Shear wave elastography (SWE) was used to measure the stiffness of the medial gastrocnemius (MG), lateral gastrocnemius (LG), and Achilles tendon (AT) in all subjects in relaxed, neutral, and standing positions.ResultsThe results showed no significant differences in the MG, LG, and AT stiffness between the dominant and non-dominant sides (p > 0.05). The MG, LG, and AT stiffness changed with positions (p < 0.05). The LG stiffness in older women was lower than in older men and young women in any position (p < 0.05). The MG stiffness in older men was greater than that in older women in any position, and age-related changes were found only in the relaxed and standing positions (p < 0.05). The AT stiffness was higher in older men only in the relaxed position (p < 0.05). There was no significant difference in AT stiffness between older and younger women at any position (p > 0.05).DiscussionThese results suggest that the bilateral gastrocnemius muscle-tendon unit stiffnesses were similar regardless of sex, age, and position. The stiffness of the gastrocnemius in women decreased with age. However, the effect of aging on AT stiffness was slight. Men have greater gastrocnemius stiffness in older adults.

Achilles Tendon Stiffness: Influence of Measurement Methodology

ObjectiveMechanical stiffness derived from force-elongation curves is fundamentally different from shear wave (SW) elastography-based tissue properties. We compared these techniques, with a total of five methods of assessing Achilles tendon (AT) stiffness. MethodsSeventeen participants (12 male and 5 female) with unilateral AT rupture performed submaximal contractions at 30% and 10% maximal isometric contraction torque of the un-injured limb. SW velocity was acquired at rest. Force-elongation curves were assessed from the free AT and the medial gastrocnemius (MG) tendon. Mechanical stiffness was determined near the end of the linear region of the force-elongation curve and from the toe region. Bivariate correlations between mechanical stiffness and SW velocity, as well as pairwise t-tests between limbs, were computed. ResultsIn the injured limb, SW velocity correlated with MG tendon and free AT toe-region stiffness during 10% (r = 0.59, p = 0.020 and r = 0.60, p = 0.011, respectively) and 30% of submaximal contractions (r = 0.56, p = 0.018 and r = 0.67, p = 0.004, respectively). The un-injured limb showed no associations. In both limbs pooled together, SW velocity correlated with MG tendon toe-region stiffness in 30% of submaximal contractions (r = 0.43, p = 0.012). Free tendon mechanical stiffness was lower in the injured limb, with a mean difference of 148.5 Nmm⁻¹ (95% CI: 35.6–261.3, p = 0.013), while SW velocity was higher in the injured limb (1.67 m × s⁻¹, 95% CI; -2.4 to -0.9, p < 0.001). ConclusionSW elastography may reflect AT viscoelastic properties at the initial slope of the force-length curve with strains <1% but cannot offer insight into AT mechanics at higher loads. Extended toe regions in the injured limb could have caused the association between mechanical stiffness and SW-based stiffness.

The Effect of Biomechanical and Viscoelastic Properties of Gastrocnemius (Lateral-Medial) Muscle and Achilles Tendon on Jumping Performance in Professional Soccer Players

Anaerobic performance (vertical jumps) is an important indicator in determining athletic performance in soccer. The aim of this study was to investigate the effects of biomechanical and viscoelastic properties of lateral and medial gastrocnemius (LG&amp;amp;MG) muscle and achilles tendon (AT) on jumping performance of professional soccer players. A total of 21 male professional soccer players with a mean age of 18.19±0.40 years, a mean height of 180.48±6.25 cm, a mean body weight of 70.71±7.82 kg, and a mean BMI of 21.66±1.65 kg/m₂ were included in this study. LG and MG muscle, as well as AT biomechanical and viscoelastic properties were evaluated with Myoton Pro device. Measurements were performed in the prone position of the soccer players, LG and MG at 50° plantar flexion, and AT at 0° (neutral position) at an angle of 4 cm above the calcaneal tubercle. Counter movement jump (CMJ) were recorded with the high-speed camera in the validated My Jump 2 application. A significant correlation was observed between the LG (F) tension value and CMJ (P) value and between the MG (R&amp;amp;C) values and the CMJ (F&amp;amp;P) value of professional soccer players (p&amp;lt;0.05). There was no significant relationship between AT values and CMJ values (p&amp;gt;0.05). It should not be forgotten that training coaches on this subject and applying this information to soccer players by conscious coaches will bring about increases in the athletic performance of soccer players, and all these performance characteristics can be achieved with planned and programmed training.

Talocalcaneal Coalition Resection with Local Fat Grafting and Flatfoot Reconstruction.

Talocalcaneal (TC) coalitions typically present in the pediatric population with medial hindfoot and/or ankle pain and absent subtalar range of motion. Coalition resection with fat interposition is well described for isolated tarsal coalitions1,2; however, patients with concomitant rigid flatfoot may benefit from additional reconstructive procedures. To address this, we employ the surgical technique of TC resection with local fat grafting and flatfoot reconstruction. This procedure is described in 3 steps: (1) gastrocnemius recession and fat harvesting, (2) TC coalition resection with local fat interposition, and (3) peroneus brevis Z-lengthening and calcaneal lateral column lengthening osteotomy with allograft. A 3 to 4-cm posteromedial longitudinal incision is made at the distal extent of the medial head of the gastrocnemius muscle. The gastrocnemius tendon is identified, dissected free of surrounding tissue, and transected. Superficial fat is then harvested from this incision before wound closure. A 7-cm incision is made from the posterior aspect of the medial malleolus to the talonavicular joint. The neurovascular bundle and flexor tendons are dissected carefully from the surrounding tissue as a group and protected while the coalition is completely resected, and bone wax and the local fat are utilized at the resection site to prevent regrowth of the coalition. An approximately 7-cm incision is then made laterally and obliquely following the Langer lines and centered over the lateral calcaneus. The peroneal tendons are released from their sheaths, and the peroneus brevis is Z-lengthened. A calcaneal osteotomy is performed about 1.5 cm proximal to the calcaneocuboid joint and angled to avoid the anterior and middle subtalar facet joints. Two Kirschner wires are inserted retrograde across the calcaneocuboid joint, and the calcaneal osteotomy is opened. A trapezoid-shaped allograft bone wedge is impacted, and the Kirschner wires are advanced across into the calcaneus. The lengthened peroneus brevis tendon is repaired, and the wound is closed in a layered fashion. First-line treatment is nonoperative with orthotics and immobilization. Surgical options include coalition resection with or without calcaneal lengthening osteotomy, arthrodesis, or arthroereisis. Following coalition resection, various grafts can be utilized, including fat autografts, bone wax, or split flexor hallucis longus tendon3-6. This procedure addresses TC coalition with concomitant rigid flatfoot. Resection alone may increase subtalar motion but does not correct a flatfoot deformity. Historically, surgeons performed arthrodesis or arthroereisis, but these are rarely performed in young patients. In patients with coalitions involving >50% of the posterior facet or preexisting degenerative changes, arthrodesis may be indicated7. Patients can expect improvement in pain and function8-11. Previous investigators reported improved patient satisfaction, improved range of motion, clinical and radiographic hindfoot correction, and an improved American Orthopaedic Foot & Ankle Society hindfoot score at the time of final follow-up8,9. Carefully free the neurovascular bundle from the surrounding soft tissue so that it can be carefully retracted away from the area of coalition resection.Utilize the interval between the posterior tibialis and flexor digitorum longus tendons to approach the coalition.Expose the medial wall of the coalition and perform a careful resection that avoids inadvertently diverging into the body of the talus or calcaneus.Place a smooth lamina spreader into the resected area and gently open the subtalar joint to confirm complete coalition resection.Place 2 retrograde wires across the calcaneocuboid joint before performing the osteotomy. Without this step, up to 50% of cases experience calcaneocuboid subluxation and/or rotation after the lateral column lengthening12.To determine the size of the allograft, place a lamina spreader into the osteotomy site to measure the width.If present, rigid supination of the forefoot must be corrected with a medial cuneiform plantar-based closing osteotomy. AOFAS = American Orthopaedic Foot & Ankle SocietyFADI = Foot and Ankle Disability IndexMRI = magnetic resonance imagingCT = computed tomographyOR = operating roomK-wire = Kirschner wire.

Effect of 6-Week Instrument-Assisted Soft Tissue Mobilization on Joint Flexibility and Musculotendinous Properties.

Instrument-assisted soft tissue mobilization (IASTM) stimulates soft subcutaneous tissues by applying pressure to the skin with a specialized bar or spurtle-like instrument. No studies have verified whether several weeks of continuous IASTM alone can alter joint flexibility and musculotendinous properties in healthy participants. We examined the effect of a 6-week IASTM program on joint flexibility and the musculotendinous properties of the lower limbs. Fourteen healthy men (aged 19-35 years) who participated in a 6-week IASTM program (3 days weekly) for the soft tissue of the posterior aspect of one lower leg were included. The other leg served as the control. Before and after the intervention, we measured the maximal ankle joint dorsiflexion angle (dorsiflexion range of motion: DFROM) and maximal passive torque (MPT), a measure of stretch tolerance. We measured muscle and tendon stiffness using shear wave elastography on the gastrocnemius and Achilles tendon. IASTM significantly increased the DFROM and MPT (p < 0.05 for both). However, no significant changes were observed in muscle and tendon stiffness. None of the parameters changed significantly in the control group. The 6-week IASTM program increased stretch tolerance and joint flexibility but did not change muscle and tendon stiffness.

Arthroscopy-Assisted Open Fabella Excision With Medial Meniscus Revision Repair

Background: The fabella is a sesamoid bone that is a normal anatomic variant yet a rare cause of pathology in the posterolateral portion of the knee. The fabella can cause chronic knee pain in patients with knee osteoarthritis and athletes at all levels and in rare cases can cause neuropathy. Initially, treatment for a painful fabella includes conservative measures, with surgical intervention after conservative treatments have failed. This technique describes our arthroscopic-assisted fabella removal technique with a concomitant medial meniscus revision repair. Indications: The goal of treatment is to relieve pain and numbness. Conservative measures (i.e., nonsteroidal anti-inflammatory drugs [NSAIDs], range of motion exercises, heel cord stretching, etc.) are the initial step in treatment. Patients are treated surgically after conservative measures have failed. The surgical approach involves an open incision, arthroscopy, or a combination. Technique Description: With the patient in the supine position, a physical examination is performed under anesthesia to compare to validate clinical findings. An open lateral knee approach helps to locate the fabella which is grasped with an Alice clap. An arthroscopy is performed, and viewing posterolaterally will confirm that the fabella is within the grips of the Alice clamp. After repair of the meniscus, the surgical bed is repositioned to identify the fabella properly. Excision of the fabella is performed sharply from the lateral gastrocnemius tendon, and palpation is demonstrated to ensure complete removal. Caution is essential to avoid complications including damage to nearby anatomic structures, such as the lateral gastrocnemius tendon, and incomplete fabella removal. Results: A clinical study by Dekker et al reported that 80% of patients were able to return to full activities and postoperative patient-reported outcomes improved from preoperative to postoperative. Fabella excision is recommended for patients with fabella pain who do not respond to conservative treatment. Discussion: We describe a technique for removing the fabella with arthroscopic assistance. Patients who have not responded appropriately to conservative treatment for a painful fabella should consider surgical intervention. With the early initiation of rehabilitation, patients will have an increased likelihood of decreased pain, resolution of symptoms, and reduced knee stiffness. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Needle‑based gastrocnemius lengthening: a novel ultrasound‑guided noninvasive technique: part II—clinical results

BackgroundIsolated gastrocnemius contracture has been associated with more than 30 lower limb disorders, including plantar heel pain/plantar fasciitis, Achilles tendinosis, equinus foot, adult flatfoot, and metatarsalgia. Although many techniques are available for gastrocnemius recession, potential anesthetic, cosmetic, and wound-related complications can lead to patient dissatisfaction. Open and endoscopic recession techniques usually require epidural or general anesthesia, exsanguination of the lower extremities and stitches and can damage the sural nerve, which is not under the complete control of the surgeon at all stages of the procedure. The purpose of this study is to evaluate the clinical results of a surgical technique for gastrocnemius lengthening with a needle, as previously described in cadaver specimens.Methods and resultsWe performed a prospective study of ultrasound-guided gastrocnemius tendon lengthening in level II using a needle in 24 cases (19 patients) of gastrocnemius contracture. The study population comprised 12 males and 7 females. Mean age was 41 years (18–64). All but 5 recessions were bilateral and occurred simultaneously. The indication for the procedure was gastrocnemius contracture; although the patients also presented other conditions such as non-insertional Achilles tendinopathy in 6 patients (2 were bilateral), insertional Achilles calcifying enthesitis in 4 (1 was bilateral), metatarsalgia in 4, flexible flat foot in 1 and plantar fasciitis in 5 (2 were bilateral). The inclusion criteria were the failure of a previous conservative protocol, that the Silfverskiöld test was positive, and that the pathology suffered by the patient was within the indications for surgical lengthening of the patients and were described in the scientific literature. The exclusion criteria were that the inclusion criteria were not met, and patients with surgical risk ASA 3 or more and children. In these patients, although possible, it is preferable to perform the procedure in the operating room with monitoring, as well as in children since they could be agitated during the procedure at the office. We used the beveled tip of an Abbocath needle as a surgical scalpel. All patients underwent recession of the gastrocnemius tendon, as in an incomplete Strayer release. We evaluated pre- and postoperative dorsiflexion, outcomes, and procedural pain (based on a visual analog scale and the American Orthopedic Foot and Ankle Society scores), as well as potential complications. No damage was done to the sural bundle.ResultsAnkle dorsiflexion increased on average by 17.89°. The average postoperative visual analog score for pain before surgery was 5.78, 5.53 in the first week, 1.89 at 1 month, and 0.26 at 3 months, decreasing to 0.11 at 9 months. The mean postoperative American Orthopedic Foot and Ankle Society Ankle-Hindfoot score the average was 50.52 before surgery, 43.42 at 1 week, 72.37 at 1 month, 87.37 at 3 months, and 90.79 at 9 months.ConclusionUltrasound-guided needle lengthening of the gastrocnemius tendon is a novel, safe, and effective technique that enables the surgeon to check all the structures clearly, thus minimizing the risk of neurovascular damage. The results are encouraging, and the advantages of this approach include absence of a wound and no need for stitches. Recovery is fast and relatively painless. A specific advantage of ultrasound-guided needle lengthening of the gastrocnemius tendon is the fact that it can be performed in a specialist's office, with a very basic instrument set and local anesthesia, thus reducing expenses.

Changes in the mechanical properties of the thigh and lower leg muscle-tendon units during the early follicular and early luteal phases.

This study aimed to determine changes in the muscle and tendon stiffness of the thigh and lower leg muscle-tendon units during the early follicular and early luteal phases, and check for possible relations between muscle and tendon stiffness in each phase. The sample consisted of 15 female university students with regular menstrual cycles. The basal body temperature method, ovulation kit, and salivary estradiol concentration measurement were used to estimate the early follicular and early luteal phases. A portable digital palpation device measured muscle-tendon stiffness in the early follicular and early luteal phases. The measurement sites were the rectus femoris (RF), vastus medialis (VM), patellar tendon (PT), medial head of gastrocnemius muscle, soleus muscle, and Achilles tendon. No statistically significant differences in the thigh and lower leg muscle-tendon unit stiffness were seen between the early follicular and early luteal phases. Significant positive correlations were found between the stiffness of the RF and PT (r = 0.608, p = 0.016) and between the VM and PT (r = 0.737, p = 0.002) during the early luteal phase. The present results suggest that the stiffness of leg muscle-tendon units of the anterior thigh and posterior lower leg do not change between the early follicular and early luteal phases and that tendons may be stiffer in those women who have stiffer anterior thigh muscles during the early luteal phase.

Exposure of Hoffa Fractures Is Improved by Posterolateral and Posteromedial Extensile Approaches: A Qualitative and Quantitative Anatomical Study.

The current literature lacks recommendations regarding surgical approaches to best visualize and reduce Hoffa fractures. The aims of this study were to (1) define surgical corridors to the posterior portions of the lateral and medial femoral condyles and (2) compare the articular surface areas visible with different approaches. Eight fresh-frozen human cadaveric knees (6 male and 2 female donors; mean age, 68.2 ± 10.2 years) underwent dissection simulating 6 surgical approaches to the distal femur. The visible articular surface areas for each approach were marked using an electrocautery device and subsequently analyzed using image-processing software. The labeled areas of each femoral condyle were statistically compared. At 30° of flexion, visualization of the posterior portions of the lateral and medial femoral condyles was not possible by lateral and medial parapatellar approaches, as only the anterior 29.4% ± 2.1% of the lateral femoral condyle and 25.6% ± 2.8% of the medial condyle were exposed. Visualization of the lateral femoral condyle was limited by the posterolateral ligamentous structures, hence a posterolateral approach only exposed its central (13.1% ± 1.3%) and posterior (12.4% ± 1.1%) portions. Posterolateral extension by an osteotomy of the lateral femoral epicondyle significantly improved the exposure to 53.4% ± 2.7% and, when combined with a Gerdy's tubercle osteotomy, to 70.9% ± 4.1% (p < 0.001). For the posteromedial approach, an arthrotomy between the anteromedial retinaculum and the superficial medial collateral ligament, and one between the posterior oblique ligament and the medial gastrocnemius tendon, allowed visualization of the central (13.5% ± 2.2%) and the posterior (14.6% ± 2.3%) portions of the medial femoral condyle, while a medial femoral epicondyle osteotomy significantly improved visualization to 66.1% ± 5.5% (p < 0.001). Visualization of the posterior portions of the femoral condyles is limited by the specific anatomy of each surgical corridor. Extension by osteotomy of the femoral epicondyles and Gerdy's tubercle significantly improved articular surface exposure of the femoral condyles. Knowledge of the surgical approach-specific visualization of the articular surface of the femoral condyles might be helpful to properly reduce small Hoffa fragments.

Tendon Elongation and Function After Delayed or Standard Loading of Surgically Repaired Achilles Tendon Ruptures: A Randomized Controlled Trial

Background: Achilles tendon ruptures often result in long-term functional deficits despite accelerated (standard) rehabilitation. Purpose/Hypothesis: The purpose of this study was to investigate if delayed loading would influence functional, clinical, and structural outcomes of the muscles and tendon 1 year after a surgical repair. It was hypothesized that delaying the loading would reduce the heel-rise height deficit 1 year after Achilles tendon rupture. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: In total, 48 patients with a surgically repaired Achilles tendon rupture were randomized to 2 groups: the standard group received the currently accepted rehabilitation, and the delayed group received the same rehabilitation except that initial loading was delayed by 6 weeks. The primary outcome was the heel-rise height difference between the injured and uninjured sides at 1 year. The secondary outcomes were (1) tendon length measured with magnetic resonance imaging, (2) muscle fascicle length and pennation angle of the gastrocnemius medialis muscle, (3) Doppler activity measured with ultrasonography, (4) Achilles tendon Total Rupture Score (ATRS), and (5) isometric muscle strength. Results: The mean heel-rise height deficits for the standard and delayed groups were −2.2 cm and −2.1 cm, respectively (P = .719). The soleus part of the tendon was already elongated 1 week after surgery in both groups without a between-group difference (side-to-side difference: standard, 16.3 mm; delayed, 17.5 mm; P = .997) and did not change over 52 weeks. The gastrocnemius tendon length was unchanged at 1 week but elongated over time without a between-group difference (side-to-side difference at 52 weeks: standard, 10.5 mm; delayed, 13.0 mm; P = .899). The delayed group had less Doppler activity at 12 weeks (P = .006) and a better ATRS (standard, 60 points; delayed, 72 points; P = .032) at 52 weeks. Conclusion: Delayed loading was not superior to standard loading in reducing the heel-rise height difference at 1 year. The data indirectly suggested reduced inflammation in the initial months and a better patient-reported outcome at 1 year in the delayed group. The soleus part of the tendon was already markedly elongated (35%) 1 week after surgery, while the length of the gastrocnemius tendon was unchanged at 1 week but was 6% elongated at 1 year. Together, these data indirectly suggest that the delayed group fared better, although this finding needs to be confirmed in future investigations. Registration: NCT04263493 (ClinicalTrials.gov identifier).

Effect of platelet-rich plasma in Achilles tendon allograft in rabbits.

Achilles tendon is composed of dense connective tissue and is one of the largest tendons in the body. In veterinary medicine, acute ruptures are associated with impact injury or sharp trauma. Healing of the ruptured tendon is challenging because of poor blood and nerve supply as well as the residual cell population. Platelet-rich plasma (PRP) contains numerous bioactive agents and growth factors and has been utilized to promote healing in bone, soft tissue, and tendons. The purpose of this study was to evaluate the healing effect of PRP injected into the surrounding fascia of the Achilles tendon after allograft in rabbits. Donor rabbits (n = 8) were anesthetized and 16 lateral gastrocnemius tendons were fully transected bilaterally. Transected tendons were decellularized and stored at -80°C prior to allograft. The allograft was placed on the partially transected medial gastrocnemius tendon in the left hindlimb of 16 rabbits. The allograft PRP group (n = 8) had 0.3 mL of PRP administered in the tendon and the allograft control group (n = 8) did not receive any treatment. After 8 weeks, rabbits were euthanatized and allograft tendons were transected for macroscopic, biomechanical, and histological assessment. The allograft PRP group exhibited superior macroscopic assessment scores, greater tensile strength, and a histologically enhanced healing process compared to those in the allograft control group. Our results suggest administration of PRP on an allograft tendon has a positive effect on the healing process in a ruptured Achilles tendon.

Observation of the Achilles Tendon and Gastrocnemius Muscle's Passive Stiffness During an Incremental Running Protocol.

Passive stiffness, a biomechanical parameter, has a potential influence on running economy, thus playing a pivotal role in performance. This study aimed to quantify passive stiffness of the Achilles tendon and gastrocnemius muscle using myotonometry throughout an incremental running protocol. Twenty-one male participants underwent a multistage incremental test (Bordeaux test) on a treadmill until exhaustion. Passive stiffness of the gastrocnemius muscle and Achilles tendon was measured using aMyotonPRO device. Measurements were taken before, during, and after the incremental test. Our findings indicated that passive stiffness of the medial gastrocnemius decreased at rest between prerun and postrun assessments (-20.12N·m-1, P = .012). Furthermore, during the test, stiffness increased at low intensity (at 50% of maximal aerobic speed: +104.8N·m-1, P = .042), returning to baseline values as intensity increased. Throughout an incremental running protocol, both Achilles tendon and gastrocnemius muscle stiffness initially increased and then decreased with escalating percentages of maximal aerobic speed. A deeper understanding of stiffness in running can inform more effective recommendations for runners' strengthening and training.

Viscoelastic materials are most energy efficient when loaded and unloaded at equal rates.

Biological springs can be used in nature for energy conservation and ultra-fast motion. The loading and unloading rates of elastic materials can play an important role in determining how the properties of these springs affect movements. We investigate the mechanical energy efficiency of biological springs (American bullfrog plantaris tendons and guinea fowl lateral gastrocnemius tendons) and synthetic elastomers. We measure these materials under symmetric rates (equal loading and unloading durations) and asymmetric rates (unequal loading and unloading durations) using novel dynamic mechanical analysis measurements. We find that mechanical efficiency is highest at symmetric rates and significantly decreases with a larger degree of asymmetry. A generalized one-dimensional Maxwell model with no fitting parameters captures the experimental results based on the independently characterized linear viscoelastic properties of the materials. The model further shows that a broader viscoelastic relaxation spectrum enhances the effect of rate-asymmetry on efficiency. Overall, our study provides valuable insights into the interplay between material properties and unloading dynamics in both biological and synthetic elastic systems.

Superficial Digital Flexor Tendon Contracture in a Dog with Gastrocnemius Tendon Avulsion

AbstractAvulsion of the gastrocnemius component of the Achilles tendon is a well-documented condition in dogs. The most common treatment is to restore tendon function with surgical reattachment to the tuber calcanei. However, repair can fail. Pantarsal arthrodesis cannot only salvage a failed repair but is also a first-line treatment that may have a more predictable outcome. We describe a case of contracture of the superficial digital flexor tendon (SDFT) in the hindlimb of a dog with avulsion of the gastrocnemius component of the Achilles tendon, treated previously by pantarsal arthrodesis. Digital flexion and lameness persisted despite non-surgical treatment, and tenotomy of the SDFT was performed at the level of distal calcaneus to allow digit extension. The dog was re-examined 2 weeks and more than 2 years after surgery. No complications occurred, and the dog maintained an excellent long-term improvement in limb function.

ISB clinical biomechanics award winner 2023: Medial gastrocnemius muscle and Achilles tendon interplay during gait in cerebral palsy

BackgroundThe interplay between the medial gastrocnemius muscle and the Achilles tendon is crucial for efficient walking. In cerebral palsy, muscle and tendon remodelling alters the role of contractile and elastic components. The aim was to investigate the length changes of medial gastrocnemius belly and fascicles, and Achilles tendon to understand their interplay to gait propulsion in individuals with cerebral palsy. MethodsTwelve young individuals with cerebral palsy and 12 typically developed peers were assessed during multiple gait cycles using 3D gait analysis combined with a portable ultrasound device. By mapping ultrasound image locations into the shank reference frame, the medial gastrocnemius belly, fascicle, and Achilles tendon lengths were estimated throughout the gait cycle. Participants with cerebral palsy were classified into equinus and non-equinus groups based on their sagittal ankle kinematics. FindingsIn typically developed participants, the Achilles tendon undertook most of the muscle-tendon unit lengthening during stance, whereas in individuals with cerebral palsy, this lengthening was shared between the medial gastrocnemius belly and Achilles tendon, which was more evident in the equinus group. The lengthening behaviour of the medial gastrocnemius fascicles resembled that of the Achilles tendon in cerebral palsy. InterpretationThe findings revealed similar length changes of the medial gastrocnemius fascicles and Achilles tendon, highlighting the enhanced role of the muscle in absorbing energy during stance in cerebral palsy. These results, together with the current knowledge of increased intramuscular stiffness, suggest the exploitation of intramuscular passive forces for such energy absorption.

Development of a multivalent adjuvanted inactivated vaccine against variant arthrotropic avian reoviruses.

Variant avian reoviruses (ARVs) are economically important emerging pathogens of poultry, which mainly affect young broiler chickens and cause significant production losses. Currently, there are no effective commercial vaccines available for control and prevention of emerging variant ARVs. In this study, monovalent inactivated adjuvated (20% Emulsigen D) broiler breeder vaccines containing antigens from ARV genotype cluster (C) group -2, -4, -5, or -6, and a multivalent vaccine containing antigens from all the four indicated genotypic cluster groups were developed and evaluated for their efficacy in protecting broiler progenies against homologous or heterologous ARV challenge. The use of monovalent or multivalent inactivated vaccines in a prime-boost immunization strategy induced the production of ARV specific antibodies in broiler breeders. The maternal antibodies were effectively transferred to broiler progenies. Broiler progenies obtained from immunized breeders demonstrated milder clinical symptoms and reduced gross and histopathological lesions after homologous ARV challenge. More severe gross and histological lesions were observed in challenged progenies from unvaccinated broiler breeders. However, cross protection was not observed when either of the monovalent-vaccine groups were challenged with a heterologous virus. In addition, the progenies from the unvaccinated ARV challenged control or heterologous ARV challenged vaccinated groups had significantly reduced body weight gain (p < 0.01) than the unchallenged-control, challenged-multivalent, or homologous ARV-challenged monovalent vaccine groups. However, homologous ARV challenged progenies in the multivalent or monovalent vaccine groups had similar body weight gain as the control unchallenged group with significantly reduced viral load (p < 0.01) in the gastrocnemius tendon tissue. This study indicates that broad-spectrum protection of broiler progenies from variant ARV infections is feasible through the development of multivalent vaccines after proper characterization, selection and incorporation of multiple antigens based on circulating ARV genotypes in targeted regions.

Differential elongation of the gastrocnemius after Achilles tendon rupture: a novel technique of selective shortening to treat push-off weakness with case series and literature review.

Differential elongation of the gastrocnemius after Achilles tendon rupture (ATR) may compromise the ability of athletes to return to competition. Recognition of this differential elongation of the gastrocnemius relative to the soleus is vital to treat patients with weakness in push-off. This paper describes a novel technique performed for selective shortening of the gastrocnemius to treat push-off weakness. Three patients with differential proximal retraction of the gastrocnemius greater than 20mm after treatment for ATR with inability to run and jump underwent surgical correction with this novel technique and were followed-up for 2years. A novel selective shortening of the gastrocnemius with autologous hamstring graft was performed in these patients. The Achilles Tendon Total Rupture Score (ATRS) and American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score were recorded preoperatively and at the final follow-up. All three patients were able to return to running and jumping at final follow-up. The ATRS improved significantly in the strength, fatigue, running and jumping domains but there appeared to be a less notable improvement in activities of daily living domain. The AOFAS score showed improvement with the greatest margin in the domain of activity limitation. This procedure is the first described selective shortening method of the gastrocnemius tendons after differential elongation following ATR. It is a safe and reliable technique providing improved ATRS and AOFAS scores in three patients who were all able to return to running and jumping sports at 2-year follow-up. IV.

Assessment of Imaging Factors Associated with Baker's Cyst Rupture on Knee MRI.

To identify the factors associated with Baker's cyst rupture on MRI. From January 2021 to December 2022, a total of 441 knee MRI examinations in 441 patients (mean age: 47.7 ± 13.8 years) with Baker's cyst were included in this study. Patients were classified into two groups: those with ruptured vs. unruptured Baker's cysts. On knee radiograph, osteoarthritis grade was assessed based on Kellgren-Lawrence grade. On MRI, combined structure injuries, alignment type between semimembranosus tendon and medial head of gastrocnemius tendon, amount of joint effusion, presence of septation, maximal diameters of cyst, and cyst volume were evaluated. Receiver operating characteristic (ROC) analysis was performed to assess the predictive performances of imaging factors for cyst rupture. There were 146 patients with Baker's cyst rupture and 295 patients without rupture. Patients with cyst rupture showed significantly longer maximal transverse diameter (25.8 ± 6.8 mm vs. 21.6 ± 5.8 mm, p = 0.035) and larger volume (13.3 ± 6.2 cm3 vs. 9.9 ± 5.1 cm3, p = 0.012) than those without rupture. On ROC analysis, maximal transverse diameter of cyst ≥ 22.2 mm (sensitivity = 64.4%, specificity = 54.9%) and cyst volume ≥ 10.9 cm3 (sensitivity = 71.2%, specificity = 58.3%) were the cutoff values for predicting rupture of cyst, respectively. The cyst volume showed significantly higher area under the curve (AUC) than maximal transverse diameter (0.726 vs. 0.642, p = 0.002). Longer transverse diameter and larger volume of Baker's cyst could be predictive imaging parameters for cyst rupture.

Dietary phytase effects on copper requirements of broilers.

Information on the availability of Cu from plant feedstuffs for broilers in the presence of phytase is scarce. The present research has been conducted with the objective of evaluating the Cu requirements of broilers when fed corn-soy diets with or without phytase. A total of 640 one-day-old male Cobb x Cobb 500, allocated into 80 battery cages with 8 chicks in each, were fed a low Cu content diet (formulated with 8.58 ± 0.21 mg/kg Cu) without phytase from placement to day 7. Starting on day 8, battery cages were distributed into a 2 × 5 factorial arrangement (phytase-added diets X 5 with graded increases of supplemental Cu) until day 28. Feeding treatments (feeds added or not with phytase and 5 graded increases of Cu) were randomly distributed with 8 cages of 8 chicks. The basal non-supplemented feeds were formulated with corn and soybean meal (SBM) without any other significant Cu contributors. Supplemental Cu was from laboratory-grade Cu sulfate pentahydrate (CuSO5H20) which was increasingly added to the feeds. Phytase was added in excess to the producer recommendation (2,500 FYT) and had average analyzed values of 2,768 ± 135.2 FYT/kg whereas analyzed Cu values were: 8.05 ± 0.25, 11.25 ± 0.15, 14.20 ± 0.40, 16.55 ± 0.05, and 19.45 ± 0.45 mg/kg. Statistics were conducted using linear and quadratic polynomial regression models. No interactions occurred between dietary Cu and phytase (p > 0.05) for any response and no effects were found for the individual factors (phytase or dietary Cu) for Ht, Hb, varus, valgus, rotated tibia, and tibia breaking strength, as well as for Cu contents in breast, gastrocnemius tendon, and kidney (p > 0.05). However, the phytase-added diets led to higher BWG, lower FCR, and increased ileal digestible Cu (p < 0.05). The gradual increase in dietary Cu produced linear increases in Cu content in livers, as well as in excreta and retention (p < 0.05). Supplementing phytase at levels expected to maximize phytate degradation was demonstrated to improve BWG and FCR; however, no effects were observed when dietary Cu was increased to a maximum of 19.45 mg/kg. An increase of 8.8% in ileal digestible Cu was observed when birds were fed phytase.

Mechanics of The Medial Gastrocnemius–Tendon Unit in Behaving more Efficiently in Habitual Non-Rearfoot Strikers than in Rearfoot Strikers during Running

This study aims to quantify how habitual foot strike patterns would affect ankle kinetics and the behavior and mechanics of the medial gastrocnemius–tendon unit (MTU) during running. A total of 14 runners with non-rearfoot strike patterns (NRFS) and 15 runners with rearfoot strike patterns (RFS) ran on an instrumented treadmill at a speed of 9 km/h. An ultrasound system and a motion capture system were synchronously triggered to collect the ultrasound images of the medial gastrocnemius (MG) and marker positions along with ground reaction forces (GRF) during running. Ankle kinetics (moment and power) and MG/MTU behavior and mechanical properties (MG shortening length, velocity, force, power, MTU shortening/lengthening length, velocity, and power) were calculated. Independent t-tests were performed to compare the two groups of runners. Pearson correlation was conducted to detect the relationship between foot strike angle and the MTU behavior and mechanics. Compared with RFS runners, NRFS runners had 1) lower foot strike angles and greater peak ankle moments; 2) lower shortening/change length and contraction velocity and greater MG peak force; 3) greater MTU lengthening, MTU shortening length and MTU lengthening velocity and power; 4) the foot strike angle was positively related to the change of fascicle length, fascicle contraction length, and MTU shortening length during the stance phase. The foot strike angle was negatively related to the MG force and MTU lengthening power. The MG in NRFS runners appears to contract with greater force in relatively isometric behavior and at a slower shortening velocity. Moreover, the lengthening length, the lengthening velocity of MTU, and the MG force were greater in habitual NRFS runners, leading to a stronger stretch reflex response potentially.