Effective and selective stretching of the medial head of the gastrocnemius

Muscle injury frequently occurs in the medial head of the gastrocnemius (MG), and stretching is used for treatment. However, there are no studies based on anatomical considerations and biomechanics. This study therefore examined the macroscopic anatomical structure of the triceps surae muscle to design an effective and selective MG stretching method, before quantitatively verifying that method by ultrasonography. The macroscopic anatomy was analyzed in 16 Japanese cadavers (25 legs). Based on the anatomical findings and the arrangement of fascicles in the MG, we concluded that ankle inversion might be advantageous for selective stretching of the tendon fiber bundles into which the MG inserts. We devised a method in which the limb was initially positioned with the knee joint in extension and the ankle joint in plantar flexion. Then, the ankle was dorsiflexed and inverted. The proposed method was compared with standard stretching and verified by ultrasonography in eight healthy adult males. This method effectively and selectively stretched the MG, producing a significantly decreased pennation angle and increased muscle fiber length. This method may be beneficial for preventing future injuries and may enhance the effect of therapy on the MG.     

Nerve dysfunction leads to muscle morphological abnormalities in chronic inflammatory demyelinating polyneuropathy assessed by MRI

Neuropathic features of chronic inflammatory demyelinating polyneuropathy (CIDP) have been well documented, however very little is known about the implication of this neuropathy on skeletal muscle, and whether nerve lesions in CIDP lead to uniform disruptions in skeletal muscles. In this study, we assessed the triceps surae complex, using magnetic resonance imaging (MRI) in a group (n = 10) of CIDP patients compared with a healthy age-matched control group (n = 9). MRI (T1 and T2) of the leg musculature as well as plantar flexion strength measurements were obtained from both groups. CIDP patients compared with controls had ∼28% lower plantar flexion strength and ∼19% less total muscle volume (T1) of the triceps surae. When strength was normalized to fat corrected triceps surae volume CIDP patients were ∼30% weaker than controls. Relaxation times from the T2 scans were significantly longer in CIDP with the soleus, medial head of gastrocnemius and lateral head of gastrocnemius showing ∼37%, ∼38% and ∼26% longer relaxation times, respectively. CIDP patients were significantly weaker compared to controls and despite normalizing strength to total triceps surae contractile tissue volume this difference remained. CIDP patients had significantly longer T2 times, reflecting increased noncontractile tissue infiltration. These results indicate reduced muscle quantity and quality as a result of alterations in axonal function. Furthermore, when present study results are considered together with a prior report on the anterior compartment (Gilmore et al. 2016, Muscle Nerve 3:413–420), it is clear that both anterior and posterior leg compartments are affected similarly in CIDP despite different terminal nerve innervation and functional properties. Clin. Anat. 32:77–84, 2019. © 2019 Wiley Periodicals, Inc.     

Achilles Tendon Lengthening for Equinus Foot with Miyoshi Myopathy: A Case Report

A 17-year-old male presented with reduced muscle strength in both lower limbs and demonstrated equinus foot (ankle equinus) in the right lower limb. Using dysferlin immunostaining, the patient was diagnosed with Miyoshi myopathy by the neurologist. Achilles tendon lengthening was performed, and a plantigrade foot without ankle equinus was achieved.     

Assessment of plantar flexors activation capacity: nerve versus muscle stimulation by single versus double pulse

This study was designed to investigate if the relationship between the interpolated twitch-torque (IT) and voluntary torque (VT) is affected by the number of electrical stimuli (single vs. double) and the stimulation site (nerve trunk vs. muscle). The results showed that the IT–VT relationship of the plantar flexors is appropriately described by a composite (linear + curvilinear) model. Indeed, whatever the stimulation method, the IT–VT relationship was linear between approximately 25 and 75% of the maximal voluntary torque (MVT) and curvilinear for higher contraction intensities. The four stimulation conditions are equivalent in assessing the maximal voluntary activation (VA% range 96.2 ± 5.0 to 98.5 ± 3.1%) as well as in determining the true maximal torque expected for total twitch occlusion (MT_exp range 171.4 ± 21.2 to 179.0 ± 26.8 Nm). The gap between the MVT and MT_exp should be viewed as an index of muscle inactivation. This gap was comparable for the four stimulation methods (2–6%) and close to the deficit in VA% (2–4%). No pulse-number effect was found on the IT–VT relationship when the nerve was stimulated but an effect on the concavity of the composite relationship was observed when the stimulation was applied over the muscle. Even though the four stimulation techniques are equivalent in assessing the maximal activation capacity our results demonstrate that the neural stimulation method is the most consistent as it guarantees the same motor pool recruitment independently from the number of pulses.     

Outcomes and complications of triceps tendon repair following acute rupture in American military personnel

IntroductionTriceps tendon ruptures are uncommon injuries primarily occurring in young, active males or elderly individuals with various systemic diseases. Relatively little is known about the epidemiology of this injury, or the results of surgical management in high-demand populations. The purpose of this study was to define the incidence and outcomes of surgical treatment in active duty American military personnel.Patients and methodsThe Military Data Repository (MDR) was queried for all active duty military personnel undergoing surgical repair or reconstruction of a triceps tendon rupture between January 2012 and December 2014. The electronic health records of all patients with at least 12 months clinical follow-up were searched for demographic information, injury details, preoperative imaging findings, post-operative complications, and ability to return to duty following surgical repair. Incidence was calculated based on total active duty population in the MDR over the study period. Risk factors for postoperative complication and inability to return to duty following surgical repair were assessed using univariate analyses.ResultsA total of 54 acute triceps tendon ruptures were identified in the search, of which 48 had at least 12 months follow-up and complete post-operative records. The incidence of acute triceps tendon rupture was 1.1 per 100,000 person-years. Twelve patients experienced post-operative complications, six of which were traumatic re-ruptures within four months of the index surgery. No patient had a post-operative infection or atraumatic repair failure. 94% of patients were able to return to active military service following surgical repair. Enlisted rank was a significant risk factor for a post-operative complication, but no factor predicted inability to return to active duty service.ConclusionsSurgical repair of acute triceps tendon ruptures reliably restores strength and function even in high-demand individuals. In our population, traumatic rerupture was the most common complication.     

Muscle weakness following sustained and rhythmic isometric contractions in man

Summary The effects of sustained and rhythmically performed isometric contractions on electrically evoked twitch and tetanic force generation of the triceps surae have been investigated in 4 healthy male subjects. The isometric contractions were performed separately and on different occasions at 30%, 60% and 100% of the force of maximal voluntary contraction (MVC). The area under the maximal voluntary contraction (MVC) force/ time curve during the rhythmic and sustained contractions was the same for each experiment. The results showed that following rhythmic isometric exercise there was a small decrease in low (10 and 20 Hz) and high (40 Hz) frequency tetanic tension which was associated with % MVC. However, there was no change in the 20/40 ratio of tetanic forces, MVC or the contraction times and force of the maximal twitch. In contrast, following sustained isometric exercise tetanic forces were markedly reduced, particularly at low frequencies of stimulation. The 20/40 ratio decreased and the induced muscle weakness was greater at 30% than 60% or 100% MVC. The performance of sustained isometric contractions also effected a decrease in contraction time of the twitch and MVC. The results are in accord with previous findings for dynamic work (Davies and White 1982), and show that if isometric exercise is performed rhythmically the effect on tetanic tensions is small and there is no evidence of a preferential loss of electrically evoked force at either high or low frequencies of stimulation following the contractions. For sustained contractions, however, the opposite is true, the ratio of 20/40 Hz forces is markedly reduced and following 30% sustained MVC there is a significant (p<0.05) change in the time to peak tension (TPT) of the maximal twitch.