Distal Musculotendinous Junction Research Articles

Rupture of the gastrocnemius muscle at its distal musculotendinous junction: conservative treatment and outcomes in 11 dogs

ABSTRACT Case history Medical records from three veterinary referral centres and a university veterinary teaching hospital in Australia and the USA were reviewed to identify dogs with a diagnosis of distal gastrocnemius musculotendinous junction rupture (DGMJR) that were treated without surgery between 2007 and 2020. Clinical and imaging findings All dogs (n = 11) presented with unilateral, pelvic limb lameness and bruising, swelling or pain on palpation at the distal musculotendinous junction. The diagnosis was confirmed with ultrasound or MRI in six dogs; radiographs were used to excluded stifle and tarsus pathology in four dogs; and five dogs were diagnosed on physical examination findings. Treatment and outcome All dogs were managed conservatively, either with complete confinement alone (n = 10; median 9 weeks), external coaptation alone (n = 1), or a combination of both (n = 4). Sporting dogs (n = 7) were completely confined (median 22 weeks) for longer periods than companion dogs (n = 3; median 5 weeks). A good to excellent outcome was achieved for all cases in this cohort. The seven sporting dogs achieved an excellent outcome; returning to their previous level of sport, with complete resolution of lameness and recovery of a normal tibiotarsal stance. The four companion dogs achieved a good outcome; returning to their previous level of activity but with persistently increased tibiotarsal standing angle compared to the contralateral limb. Clinical relevance Conservative treatment represents a viable treatment option for dogs with a rupture of the gastrocnemius muscle at its distal musculotendinous junction.

Characterization of the Proximal Long Head of Biceps Tendon Anatomy Using Magnetic Resonance Imaging: Implications for Biceps Tenodesis

Background: Biceps tenodesis is a common treatment for proximal long head of biceps (LHB) tendon pathology. To maintain biceps strength and contour and minimize cramping, restoration of muscle-length tension and appropriate positioning of the tenodesis is key. Little is known about the biceps musculotendinous junction (MTJ) anatomy, especially in relation to the overlying pectoralis major tendon (PMT), which is a commonly used landmark for tenodesis positioning. Purpose: To characterize the in vivo topographic anatomy of the LHB tendon, in particular the MTJ relative to the PMT, using a novel axial proton-density magnetic resonance imaging (MRI) sequence. Study Design: Descriptive laboratory study. Methods: In total, 45 patients having a shoulder MRI for symptoms unrelated to their biceps tendon or rotator cuff were prospectively recruited. There were 33 men and 12 women, with a mean age of 37 ± 13 years (range, 18-59 years). All patients underwent routine shoulder MRI scans with an additional axial proton density sequence examining the LHB tendon and its MTJ. Three independent observers reviewed each MRI scan, and measurements were obtained for (1) MTJ length, (2) the distance between the proximal MTJ and the superior border of the PMT (MTJ-S), (3) the distance between the distal MTJ to the inferior border of the PMT, and (4) the width of the PMT. Results: The average position of the MTJ-S was 5.9 ± 10.8 mm distal to the superior border of the PMT. The mean MTJ length was 32.5 ± 8.3 mm and the width of the PMT was 28.0 ± 7.3 mm. We found no significant correlation between patient age, height, sex, or body mass index and any of the biceps measurements. We observed wide variability of the MTJ-S position and identified 3 distinct types of biceps MTJ: type 1, MTJ-S above the PMT; type 2, MTJ-S between 0 and 10 mm below the superior border of the PMT; and type 3, MTJ-S >10 mm distal to the superior PMT. Conclusion: In this study, the in vivo anatomy of the LHB tendon is characterized relative to the PMT using a novel MRI sequence. The results demonstrate wide variability in the position of the MTJ relative to the PMT, which can be classified into 3 distinct subtypes or zones relative to the superior border of the PMT. Understanding this potentially allows for accurate and anatomic placement of the biceps tendon for tenodesis. Clinical Relevance: To our knowledge, this is the first study to radiologically analyze the in vivo topographic anatomy of the LHB tendon and its MTJ. The results of this study provide more detailed understanding of the variability of the biceps MTJ, thus allowing for more accurate placement of the biceps tendon during tenodesis.

Noncontrast Magnetic Resonance Imaging of Perforators for Preoperative Evaluation of Anterolateral Thigh Flaps.

Background:The anterolateral thigh (ALT) flap is a commonly utilized perforator-based flap in reconstructive surgery. Although previous studies have used various angiographic techniques to preoperatively image ALT perforators, none have investigated the efficacy of noncontrast magnetic resonance imaging (MRI). Our study investigates the efficacy of our institutional fat suppression noncontrast MRI sequence to characterize the number, location, and course of dominant skin perforators in the ALT for preoperative planning.Methods:We queried our institutional database for 100 noncontrast thigh MRIs from July 2013 to July 2018 that included an axial fat suppression sequence with visualization from the lesser trochanter to the distal musculotendinous junction of the rectus femoris. Perforator course, size, and location relative to bony landmarks were determined.Results:Of the 100 examinations, 70 included bilateral thighs for a total of 170 thighs for perforator analysis. An estimated 277 perforators were identified, of which 101 were septocutaneous (36.5%) and 176 were musculocutaneous (63.5%). An average of 1.63 perforators were visualized in each thigh (min, 1; max, 4). The average perforator diameter at exit from the anterior thigh compartment fascia was 2.5 mm (SD, 0.5). Perforator exit location along the anterior superior iliac spine- or lesser trochanter-patella line could be determined for n = 57 perforators and mapped into 3 predictable clusters.Conclusions:At least 1 perforator was found in each of 170 thighs imaged. Perforator course, size, and location measured with noncontrast MRI are consistent with prior literature. Noncontrast MRI is a low-morbidity imaging modality that may serve as an effective tool in preoperative planning of the ALT flap.

Open Repair of Acute Proximal Adductor Magnus Avulsion

Hip adduction is accomplished through coordinated effort of the adductor magnus, brevis, and longus and the obturator externus and pectineus muscles. Each of these muscles may be injured at its proximal or distal insertion or in its midsubstance. The incidence of injuries to the adductor complex is difficult to determine in sport because of players' underreporting and playing through minor strains. The most commonly injured adductor muscle is the adductor longus muscle. The injury most frequently occurs at the proximal or distal musculotendinous junction, but several case reports of origin and insertional ruptures of the adductor longus exist in the literature. Successful outcomes have been obtained with both operative and nonoperative approaches in these cases. Reports of isolated proximal avulsion of the adductor magnus are less common. This article describes our surgical technique for management of a rare acute proximal adductor magnus avulsion.

The use of platelet-rich plasma (PRP) in the treatment of gastrocnemius strains: a retrospective observational study

The aim of the present retrospective observational study was to evaluate the time of functional recovery following a specific combined therapeutic approach characterized by an active exercise therapy carried out immediately after Platelet-rich plasma (PRP) injections for the treatment of the muscular lesion of the distal musculotendinous junction of the gastrocnemius medial head.Medical records of 31 subjects treated with three PRP intra-lesional ultrasound guided injections and 30 patients treated with the standard therapeutic approach (control group) were analyzed. Both groups followed the same rehabilitation therapy. Patients in the control group were able to start active exercise with a significant delay when compared to the PRP treated subjects: 17 ± 7.2 days and 9 ± 3.8 days (p = 0.0001), respectively. This delay was mainly due to the persistence of pain in the subjects in the control group. The time necessary to return to walk without pain was significantly shorter in the PRP treated group: 24.27 ± 12.36 days versus 52.4 ± 20.03 days in the control group (p < 0.001) as well as the time needed to fully return to practice the previous sport activity: 53.33 ± 27.74 days versus 119.3 ± 43.87 days in the control group (p < 0.001).The present study showed that ultrasound guided delivery of PRP into the site of muscle injury has to be considered a valid therapeutic approach with the potentiality of significantly reduce time and costs for reaching a complete functional recovery.

Continuous Ultrasound Decreases Pain Perception and Increases Pain Threshold in Damaged Skeletal Muscle.

Determine whether therapeutic ultrasound (TUS) delivered in a continuous mode reduces pain perception after muscle injury. Randomized, double-blind trial. Institutional laboratory. Twenty young healthy participants (11 females; 9 males; mean age ± SD, 24.1 ± 3.7 years). All subjects performed 50 maximal eccentric contractions of the biceps brachii on a Biodex dynamometer. Criterion measures of isometric force production and serum creatine kinase (CK) activity confirmed tissue damage. Both groups received either TUS or sham treatment everyday starting 24 hours after muscle damage. Muscle soreness and pain were assessed at baseline, 48 hours postdamage, and every other day for 8 days. Muscle pain was assessed with a battery of tests: visual analog scale (VAS), Short-form McGill Pain Questionnaire-2, joint angle changes, and mechanical pressure threshold. Confirmation of damage occurred with baseline compared to 48 hours after damage of isometric peak torque (N·m; P < 0.01) and CK activity (IU/I; P = 0.03). Our results showed significant treatment group differences in VAS (P = 0.01) and mechanical pressure threshold (P = 0.02) after the third TUS treatment in the distal bicep brachii region. Continuous TUS reduced pain perception and increased mechanical pressure threshold in the biceps brachii after muscle damage, specifically near the distal musculotendinous junction.

A Proximal Fibularis Brevis Muscle Is Associated with Longitudinal Split Tendons: A Cadaveric Study

The anomalous distal musculotendinous junction of the fibularis brevis muscle has been hypothesized to contribute to the development of longitudinal fibularis brevis tendon tears. Specifically, the mass effect of the low-lying fibularis brevis muscle belly was thought to increase the pressure on the superior peroneal retinaculum and increase the probability of fibularis brevis tendon subluxation. A more recent examination of the fibularis brevis tendon junction found, contrary to this hypothesis, a statistically significant association between an anomalous proximal musculotendinous junction and the prevalence of longitudinal split tears. However, no rationale was offered. The present study examined the relationship between the musculotendinous junction and the prevalence of longitudinal fibularis brevis tendon tears. A total of 24 fibularis brevis tendon lengths were measured bilaterally in 12 human cadaveric specimens. The tendon lengths were assessed as the vertical distance from the most inferior aspect of the lateral malleolus to the most distal fibularis brevis musculotendinous extension. Only full-thickness tears were identified and included. The lengths of tendons with and without longitudinal tears were compared. Of the 24 tendons examined, 7 (29%) presented with full-thickness longitudinal tears from 4 cadavers (33%). The mean length for the tendons with tears was significantly longer (p < .001) than the mean length of those without tears (28.86 ± 3.02 mm versus 16.29 ± 7.30 mm). Our research concurs with the most recent findings, identifying a statistically significant association between an anomalous proximal muscle belly extension and longitudinal fibularis brevis tendon tears. Furthermore, we propose the hypothesis that a more proximal musculotendinous junction might predispose individuals to a lesser stabilizing effect of the muscle against the posterior lateral surface of the fibula, increasing the probability of anterolateral subluxation, attrition, and longitudinal tear development.

Hamstring injuries in elite Gaelic football: an 8-year investigation to identify injury rates, time-loss patterns and players at increased risk

BackgroundHamstring injuries occur frequently in field sports, yet longitudinal information to guide prevention programmes is missing.AimInvestigate longitudinal hamstring injury rates and associated time loss in elite Gaelic football, while identifying...

Regional Difference In Gastrocnemius Tension During Passive Stretching As Assessed With Shear Wave Elastography

Muscle strain injuries occur when the muscle is either stretched passively or activated during stretch. Calf strain injuries are most commonly found in the medial gastrocnemius (MG), especially at the distal musculotendinous junction. One of the reasons for the susceptibility of musculotendinous junction for strain injuries may be that the distal region of MG is stretched more than the medial belly region. Muscle tension during passive stretching can be estimated from shear elastic modulus measured by shear wave elastography. PURPOSE: To investigate the regional difference in MG tension during passive stretching, shear elastic modulus at the distal and medial belly regions of the MG was assessed by shear-wave elastography. METHODS: Twenty-two healthy men and 25 healthy women participated in this study. Shear elastic moduli at the distal and medial belly regions of the MG were measured with the ankle joint positions at 30° plantarflexion (PF), a neutral anatomical position (NE), and 20° dorsiflexion (DF). The regional differences in the shear elastic modulus were tested with a two-way analysis of variance (region of the MG × ankle joint position), followed by t-tests with Bonferroni correction, with the significance set at P < 0.05. RESULTS: Shear elastic modulus was not significantly different between the distal and medial belly regions at PF (distal region: 5.7 ± 2.0 kPa; medial belly region: 5.0 ± 1.4 kPa) and NE (distal region: 9.8 ± 1.6 kPa; medial belly region: 9.9 ± 1.8 kPa), but it was significantly higher at the distal region (40.7 ± 10.1 kPa) compared with the medial belly region (35.9 ± 9.1 kPa) at DF. CONCLUSIONS: Regional difference in MG tension during passive stretching was observed in the ankle joint position where the MG is sufficiently lengthened, which could lead to muscle strain injuries at the distal musculotendinous junction of the MG. The study was supported by JSPS KAKENHI (Grant Number 15K16500).

Ultrasound Imaging of Torn Soleus Muscle

Figure 1. In comparison with the normal side, the left calf appeared markedly swollen, without noticeable ecchymosis. A 51-year-old man was referred for ultrasound (US) examination because of persistent left calf swelling for 3 months. The swelling developed abruptly after he had stumbled against a stone, sustaining an inversion injury to his ankle. He described calf pain and swelling but no ecchymosis. Three months after injury, active and passive range of motion of the ankle and toes were not limited, including ankle plantar flexion and toe flexion. Skin color and sensation also appeared normal over the swollen area (Figure 1). US imaging revealed a hyperechoic, homogeneous mass originating beneath the mid-portion of the Achilles tendon and ending at the posterior proximal tibia, with an intact distal musculotendinous junction of the medial gastrocnemius muscle (Supplemental Video and Figure 2A). The mass was observed to occupy the space between both heads of the gastrocnemius and deep plantar flexors (tibialis posterior, flexor digitorum profoundus and flexor hallucis longus), with overlying anechoic fluid (Supplemental Video and Figure 2B). The patient was eventually diagnosed with tear of the soleus muscle and an organized hematoma. The soleus muscle, originating from the fibula and medial border of the tibia, merges with the gastrocnemius muscle, forming the Achilles tendon and attaching on the calcaneus. Tear of the medial head of the gastrocnemius muscle at the musculotendinous junction (ie, “tennis leg”) is the more common calf muscle tear, and is typically caused by abrupt extension of the knee and simultaneous forced dorsiflexion of the ankle [1,2]. In this patient, there had been a severe ankle sprain with simultaneous knee buckling. As such, although his gastrocnemius muscle had been protected from overload, the soleus muscle had become vulnerable to the twisting force. In addition, we conclude that the lack of ecchymosis could be attributed to the intact

Paper 79: Semitendinosus Tendon Regeneration after ACL Reconstruction: A Morphological and Functional Study

Paper 79: Semitendinosus Tendon Regeneration after ACL Reconstruction: A Morphological and Functional Study

Acute rectus femoris rupture at the distal musculotendinous junction in a football player

aUniversity College Hospital, London, United Kingdom bMarylebone Physiotherapy & Sports Medicine, London, United Kingdom Financial Disclosure: The authors declare no conflicts of interest. Correspondence to Joris A. Jansen, MD, Clinical Fellow Orthopaedics & Trauma, University College Hospital, Euston Road 250, NW1 2BU London Tel: +0044 7722980389; fax: +0031 619430215; e-mail: [email protected]

Pictorial essay: Ultrasonography in ′tennis leg′

Tennis leg is caused by a rupture of the medial head of the gastrocnemius muscle, usually at its distal musculotendinous junction region. However, tears in this muscle and its tendon are also included under the term ‘tennis leg’. It is seen regularly in practice and is an important cause of a painful calf. The common USG findings include: disruption of the pinnate pattern of the distal medial gastrocnemius, usually near the junction of the triceps surae (which is the echogenic line between the gastrocnemius, the soleus, and the plantaris muscles), fluid tracking along the fascia, adjacent hematoma, and intramuscular tears as well as hematomas. USG is useful for confirming the diagnosis, excluding other causes of a painful calf, for assessing the severity of the disease, and in follow-up.

Bifid insertion of the distal biceps brachii tendon with isolated rupture: Magnetic resonance findings

Rupture of the distal biceps brachii tendon is greatly outnumbered by rupture of the proximal attachment of the long head from the bicipitolabral anchor at the superior glenoid, with rupture of the origin of the proximal tendon of the short head of biceps an exceedingly uncommon injury. 1 Athwal G.S. Steinmann S.P. Rispoli D.M. The Distal Biceps Tendon: Footprint and Relevant Clinical Anatomy. J Hand Surg [Am]. 2007; 32: 1225-1229 Abstract Full Text Full Text PDF PubMed Scopus (147) Google Scholar , 2 Bernstein A.D. Breslow M.J. Jazrawi L.M. Distal biceps tendon ruptures: a historical perspective and current concepts. Am J Orthop. 2001; 30: 193-200 PubMed Google Scholar , 3 DiChristina D.G. Lustig K.A. Rupture through the short head of the biceps muscle belly. A case report. Clin Orthop Relat Res. 1991; 277: 139-141 Google Scholar A recent case of a bifurcated distal biceps tendon demonstrating selective disruption of a single tendon bundle has been reported that was surgically confirmed and subsequently underwent successful primary repair. 4 Eames M.H. Bain G.I. Fogg Q.A. van Riet R.P. Distal biceps tendon anatomy: a cadaveric study. J Bone Joint Surg Am. 2007; 89: 1044-1049 Crossref PubMed Scopus (147) Google Scholar If the clinical scenario demands surgical restoration due to functional disability, then accurate preoperative detection is paramount because this injury may be confused with a partial thickness tear of a nonbifurcated distal biceps tendon or a distal musculotendinous junction strain, both which are typically managed conservatively.

A novel approach to sonographic examination in a patient with a calf muscle tear: a case report

IntroductionRupture of the distal musculotendinous junction of the medial head of the gastrocnemius, also known as "tennis leg", can be readily examined using a soft tissue ultrasound. Loss of muscle fiber continuity and the occurrence of bloody fluid accumulation can be observed using ultrasound with the patient in the prone position; however, some cases may have normal ultrasound findings in this conventional position. We report a case of a middle-aged man with tennis leg. Ultrasound examination had normal findings during the first two attempts. During the third attempt, with the patient's calf muscles examined in an unconventional knee flexed position, sonographic findings resembling tennis leg were detected.Case presentationA 60-year-old man in good health visited our rehabilitation clinic complaining of left calf muscle pain. On suspicion of a ruptured left medial head gastrocnemius muscle, a soft tissue ultrasound examination was performed. An ultrasound examination revealed symmetrical findings of bilateral calf muscles without evidence of muscle rupture. A roentgenogram of the left lower limb did not reveal any bony lesions. An ultrasound examination one week later also revealed negative sonographic findings. However, he still complained of persistent pain in his left calf area. A different ultrasound examination approach was then performed with the patient lying in the supine position with his knee flexed at 90 degrees. The transducer was then placed pointing upwards to examine the muscles and well-defined anechoic fluid collections with areas of hypoechoic surroundings were observed.ConclusionFor patients suffering from calf muscle area pain and suspicion of tennis leg, a soft tissue ultrasound is a simple tool to confirm the diagnosis. However, in the case of negative sonographic findings, we recommend trying a different positional approach to examine the calf muscles by ultrasound before the diagnosis of tennis leg can be ruled out.

Failure sites and peak tensile forces of the composite triceps surae muscle by passive extension in the rabbit

The triceps surae muscle-tendon unit of rabbit was tested by a passive extension technique. The effects of different stretch rates were evaluated. Functioning as a composite muscle-tendon unit, the triceps surae responded viscoelastically to the tensile loads. The sites of failure were consistent at the muscular portion near the musculotendinous junction. Failure occurred within 0.1–1.0 mm of the distal musculotendinous junction for the soleus muscle and within 5–10 mm proximal to the distal musculotendinous junction in the lateral head of gastrocnemius muscle. In the medial head of gastrocnemius muscle failure occurred within 15–30 mm proximal to the distal musculotendinous junction. There was a greater peak tensile force requirement and a greater energy absorption when tested with faster stretch rates. These results furnish evidence that the biomechanical property of composite musculotendinous unit is strain-rate dependent and behaves viscoelastically.

The effects of passive warming on muscle injury

This study investigated the effects of passive warming on the biomechanical properties of the musculotendinous unit. Paired tibialis anterior (TA) and extensor digitorum longus (EDL) muscles in the rabbit hindlimb were passively heated to different temperatures and then subjected to controlled strain injury. The parameters examined were: 1) percent increase in length to failure, 2) force to failure, 3) energy absorbed by the musculotendinous unit to failure, and 4) site of failure. Warmed (39 degrees C +/- 0.5 degrees C) TA (P less than or equal to 0.01) and EDL (P less than or equal to 0.05) muscles achieved a greater increase in length from rest before failing than did their contralateral controls at 35 degrees C +/- 0.5 degrees C. In both the TA and EDL the force at failure was greater at 35 degrees C than at 39 degrees C, although the difference was significant for only the EDL (P less than or equal to 0.05). The energy absorbed (area beneath the length-tension curve) by both the TA and EDL was greater at 39 degrees C, but these differences were not significant. All muscles failed at the distal musculotendinous junction. These data suggest that passive warming increases the extensibility of the musculotendinous unit and may thereby reduce its susceptibility to strain injury.

Biomechanical comparison of stimulated and nonstimulated skeletal muscle pulled to failure.

We compared the biomechanical properties of passive and stimulated muscle rapidly lengthened to failure in an experimental animal model. The mechanical parameters compared were force to tear, change in length to tear, site of failure, and energy absorbed by the muscle-tendon unit before failure. Paired comparisons were made between 1) muscles stimulated at 64 Hz (tetanic stimulation) and passive (no stimulation) muscles, 2) muscles stimulated at 16 Hz (wave-summated stimulation) and passive muscles, and 3) muscles stimulated at 64 Hz and at 16 Hz. Both tetanically stimulated and wave-summation contracted muscles required a greater force to tear (at 64 Hz, 12.86 N more, P less than 0.0004; and at 16 Hz, 17.79 N more, P less than 0.003) than their nonstimulated controls, while there was no statistical difference in failure force between muscles stimulated at 16 Hz and 64 Hz. The energy absorbed was statistically greater for the stimulated muscles than for the passive muscles in Groups 1 and 2 (at 64 Hz, 100% more, P less than 0.0003; and 16 Hz, 88% more, P less than 0.0002). In Group 3, the tetanically contracted muscle-tendon units absorbed 18% more energy than the wave-summated stimulated muscles (P less than 0.01). All muscles tore at the distal musculotendinous junction, and there was no difference in the length increase at tear between muscles in each group. These findings may lead to enhanced understanding of the mechanism and physiology of muscle strain injuries.