How does ballet training alter ankle tendinous morphology and hemodynamics in asymptomatic pre-professional dancers? An ultrasonographic study

Objectives

Among symptomatic dancers, sonographic abnormalities are common. Whether asymptomatic dancers have any abnormalities remains unknown. Some dancers became cyanosis over distal feet after ballet training. The hemodynamic changes at the feet in ballet are not clearly understood.

Extensor hallucis longus muscle contracture after distal tibial physeal injury: A report of two cases

Few studies have reported about isolated contracture in the extensor hallucis longus (EHL) muscle, but none of the EHL muscle contracture after distal tibial physeal injury. Two such cases in 16- and 14-year-old boys who underwent surgeries for distal physeal injury of the tibia at a previous hospital are presented. Extension contracture of the hallux appeared 1–2 months post-surgery. Physical examinations revealed that the extension contracture of the first metatarsophalangeal joint was aggravated in plantar flexion of the ankle due to a tenodesis effect, and magnetic resonance imaging showed atrophy and signal changes in the anterior compartment muscles. This was diagnosed as EHL muscle contracture due to anterior compartment syndrome (ACS) after distal tibial physeal injury. The EHL tendon transfers were performed in both cases, with favorable short-term results. Therefore, the EHL tendon transfer might be preferable in case of the EHL muscle contracture due to partial ACS.     

Intradural Disc Herniation in the Setting of Congenital Lumbar Spinal Stenosis

IntroductionAccounting for an estimated 1.10-1.76% of all lumbar herniations, lumbar intradural disc herniation (IDH) occurs primarily in males during the fourth to fifth decades of life. While not validated, congenital lumbar spinal stenosis (CLSS) is implicated as one precipitating factor for IDH.Case reportWe report 28-year-old Hispanic female with CLSS, severe obesity, and degenerative disk disease, with a history of minimally invasive surgical (MIS) decompression for a large paracentral L4-5 disc herniation at 25. After three years, the patient developed sudden burning dysesthesias in the L4-5 dermatomes bilaterally and temporary leg weakness. Lumbar magnetic resonance imaging exhibited severe L4-5 spinal stenosis, and the patient underwent repeat MIS decompression, which again provided her with adequate symptom resolution. However, 20 days postoperatively she developed cauda equina syndrome with anal dysfunction, and bilateral leg and foot weakness. Upon open surgical exploration we discovered a tense L4-5 dural protrusion. After a dorsal durotomy, a large IDH with a ventral dural tear was identified. Subsequent to adequate debulking of the IDH, the ventral tear was repaired, and an expansile duraplasty was performed. Overall, the patient's bladder and bowel function, pain, hypoesthesia, and motor strength all improved. Two weeks after surgery she presented with a lumbar pseudomeningocele that was managed conservatively.ConclusionThis report not only highlights an atypical presentation of IDH and is the first case of CLSS linked with IDH, lending support to the hypothesis that CLSS can lead to IDH, but also provides a comprehensive review of IDHs.     

Biosynthesis and degradation of acetylcholine receptors in rat skeletal muscles. Effects of electrical stimulation.

Synthesis and degradation of acetylcholine receptors in rat skeletal muscles were measured in organ culture. The rate of de novo biosynthesis and incorporation of acetylcholine receptors into extrajunctional membranes of denervated muscles was measured by determining the rate of appearance of [1] [²H, ¹³C, ¹⁵N]-acetylcholine receptors when muscles were cultured in medium containing [1] [²H, ¹³C, ¹⁵N]-amino acids. Denervated extensor digitorum longus and soleus muscles were found to synthesize new receptors for several days in organ culture at an average rate of 1.4%/h. The degradation rates for extrajunctional and junctional acetylcholine receptors were estimated by irreversibly labeling acétylcholine receptors on muscles with radioactive iodinated α-bungarotoxin and measuring the rate of release into the culture medium of mono- and di-iodotyrosine, breakdown products of the radioactive α-bungarotoxin. The rates of this proteolytic process yielded average lifetimes of 22 h and 13 days for [¹²⁵I]α-bungarotoxin bound to extrajunctional and junctional receptors, respectively, probably reflecting the average lifetimes of the acetylcholine receptors.Electrical stimulation at 100Hz for 1 s every 80s, producing visible contraction, but not maximal tetanic tension, barely altered the rate of incorporation of new acetylcholine receptors into the extrajunctional plasma membrane of extensor digitorum longus and soleus muscles, even when the stimulation continued for 5 days. Supra-maximal stimulation, resulting in maximal tetanic tension, with the same stimulation pattern produced a rapid decline of 10–20% in the rate of new receptor production and a corresponding decline in overall protein synthesis. Stimulation beyond 18–24 h (up to 68 h) resulted in a further decrease in new receptor production to about 30% of the control rate, but not more. Stimulation for longer than 16 h produced less than a 5–10% decrease in overall protein synthesis, compared with control muscles. The same pattern of electrical stimulation, producing maximal tetanic tension, had no effect on the apparent degradation rate of extrajunctional receptors in denervated muscles.Our results show that denervated adult muscle can be maintained in organ culture for at least 1 week, and that the muscles in culture will continue to degrade acetylcholine receptors and to synthesize new receptors, even when electrically stimulated for 5 days. The significance of this study is that electrical stimulation, producing frequent tetanic contractions, can affect extrajunctional acetylcholine receptor metabolism by selectively decreasing de novo synthesis, the receptor degradation remaining unchanged. The precise control point in the biosynthetic process has yet to be determined. However, our results indicate that electrically induced activity does exert a regulating influence, relatively rapidly, on extrajunctional acetylcholine receptor metabolism on muscles maintained in vitro.     

Intracellular uptake and degradation of extracellular tracers in mouse skeletal muscle in vitro: The effect of denervation

Innervated and chronically denervated mouse skeletal muscles have been incubated under various conditions in a Ringer solution containing one of the three macromolecules: [³H]α-neurotoxin, [³H]inulin and horseradish peroxidase. Following extensive wash-out for 4 h of the extracellular compartment, the amount of each macromolecule retained intracellularly was obtained.Intracellular uptake of a [³H]monoacetylated α-neurotoxin in vitro at 37°C was found to be increased in denervated mouse extensor digitorum longus muscles compared to innervated control muscles. Similarly, the uptake in vitro at 37°C of [³H]inulin and horseradish peroxidase was also increased in denervated muscles. At 4°C the uptake of [³H]inulin and horseradish peroxidase was markedly reduced. Protamine was found to stimulate the uptake of [³H]inulin at 37°C but not at 4°C. Reduction in specific activity by addition of 50-fold excess of unlabelled inulin failed to affect the uptake of [³H]inulin suggesting that this uptake process obeyed bulk kinetics. Furthermore, the endocytized [³H]inulin was found to be strongly retained in the muscles since prolonged washing or addition of unlabelled inulin to the washing solution did not reduce the uptake.Characterization of [³H]inulin taken up by the muscles was performed by gel chromatography on Sephadex G-25. Using a purified [³H]inulin solution it was observed that about 45% of the total radioactivity remaining in the muscles was eluted as [³H]inulin. Additional radioactivity consisted of lower molecular weight compounds. These degradation products of [³H]inulin were only present in the muscle homogenate and were not detected in the incubation solution.The results suggest that intracellular uptake of different macromolecules by endocytosis in skeletal muscles increases following denervation, and that following uptake, degradation of the endocytized material may occur.     

椎动脉、颈交感干和颈长肌的解剖关系及其在颈椎手术中的意义

目的研究椎动脉、颈交感干和颈长肌的相互关系,为颈椎前入路手术提供参考资料。方法采用12具正常尸体标本,测量椎动脉起始部至第6颈椎(C6)横突孔间距及其与前斜角肌内侧缘的夹角,并测量C6水平椎动脉至颈长肌内侧缘的距离、两颈长肌内侧缘的距离、颈交感干至颈长肌内侧缘的距离、颈交感干至颈正中线的距离。结果椎动脉起始部至第6颈椎横突孔的间距为(47.76±17.28)mm。在C6水平椎动脉至颈长肌内侧缘的距离为(8.25±2.03)mm,与前斜角肌内侧缘的夹角为24.28°±2.13,°两颈长肌内侧缘的距离为(13.78±1.49)mm,颈交感干至颈长肌内侧缘的距离为(14.57±1.62)mm,至颈正中线的距离为(20.64±2.42)mm。结论颈椎前入路手术中对椎动脉及颈交感干的定位应参照颈长肌、前斜角肌等重要标志,并应注意椎动脉可能的变异。在C6水平,颈交感干与颈长肌的距离最近,为手术中容易误伤的结构。     

Complex Anatomic Abnormalities of the Lower Leg Muscles and Tendons Associated With Phocomelia: A Case Report

Musculoskeletal anatomy is widely known to have components that stray from the norm in the form of variant muscle and tendon presence, absence, origin, insertion, and bifurcation. Although these variant muscles and tendons might be deemed incidental and insignificant findings by most, they can be important contributors to pathologic physiology or, more importantly, an option for effective treatment. In the present case report, we describe a patient with phocomelia and Müllerian abnormalities secondary to in utero thalidomide exposure. The patient had experienced recurrent bilateral foot pain accompanied by numbness, stiffness, swelling, and longstanding pes planus. These symptoms persisted despite conservative treatment with orthotics, steroids, and nonsteroidal anti-inflammatory drugs. Radiographic imaging showed dysmorphic and degenerative changes of the ankle and foot joints. Further investigation with magnetic resonance imaging revealed complex anatomic abnormalities, including the absence of the posterior tibialis and peroneus brevis, lateralization of the peroneus longus, and the presence of a variant anterior compartment muscle. The variant structure was likely a previously described anterior compartment variant, anterior fibulocalcaneus, and might have been a source of the recurrent pain. Also, the absence of the posterior tibialis might have caused the pes planus in the present patient, considering that posterior tibialis tendon dysfunction is the most common cause of acquired pes planus. Although thalidomide infrequently affects the lower extremities, its effects on growth and development were likely the cause of this rare array of anatomic abnormalities and resulting ankle and foot pathologic features.     

自体同侧腓骨长肌腱在青年前交叉韧带重建中的应用与疗效

目的 探讨自体同侧腓骨长肌腱在青年前交叉韧带重建的可行性及其早期疗效。方法 收集我科自2013年 5月至 2018年5月采用关节镜下自体腓骨长肌腱重建膝关节前交叉韧带40例,男35例,女5例,年龄18～35岁,平均年龄24.8岁,手术取自体同侧腓骨长肌重建前交叉,股骨端用可调节带袢锁扣钛板固定,胫骨端以界面螺钉固定,术后评估包括临床检查, Lysholm膝关节功能评分,AOFAS踝关节功能评分。结果 40例患者均获随访,随访时间12～36月,平均随访时间25月, Lysholm膝关节功能术后末次随访的评分为(92.65±0.44),高于术前的(50.65±0.68),P＜0.01。结论 自体同侧腓骨长肌腱在青年前交叉韧带重建的应用疗效早期令人满意,取腓骨长肌腱后对踝关节功能无明显影响。