Search

The deep peroneal nerve (DPN) passes over the dorsum of the foot and is susceptible to injury during surgical approaches. The purpose of this anatomical study is to examine the relationship of the extensor hallucis brevis (EHB) as it passes over the DPN. Ten cadaver feet specimens were dissected and the anatomical structures surrounding the neurovascular bundle containing the DPN were examined. In nine out of the ten specimens the DPN was under the EHB musculotendinous junction. In one case it passed through the musculotendinous junction. This cadaver study has found a consistent easily identifiable landmark for protecting the neurovascular bundle containing the DPN during dorsal midfoot surgery.

Proximal lacerations of the extensor tendon apparatus can pose a surgical challenge, especially when located at the musculotendinous junction or in patients presenting late. We describe a technique to augment the suture repair of these injuries utilizing local harvested strips of dorsal forearm fascia.

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.

Soft-tissue defects of the distal third of the tibia are considered to be the realm of free-tissue transfer. We have found clinically that several local muscles can be used reliably in this area. The purposes of this study were: (1) to evaluate the potential use of the local muscles for soft-tissue coverage in the lower third of the leg and (2) to obtain numerical data that could be used preoperatively in the selection of potential local muscle flaps. All potential muscles, excluding the gastrocnemius, plantaris, and popliteus, from 10 fresh frozen legs were examined and the following details recorded: (1) the distance above the medial malleolus that the muscle bellies ended (musculotendinous junction), (2) the distance between the medial malleolus and the distal end of the transposed flaps (reach), (3) the area of tibia that could be covered, and (4) the vascular supply to these muscles. The soleus, extensor digitorum longus and peroneus tertius, extensor hallucis longus, peroneus brevis, and flexor digitorum longus were found to be the most anatomically suited muscles for local transposition to selected lower-third defects. We have worked with these muscles clinically and have found them to be useful and reliable when chosen appropriately.

Introduction The plantaris tendon is increasing recognised as an important factor in midportion Achilles tendinoapathy. Recent cadveric 1 and histological studies 2 lend support to the theory that the plantaris tendon may be involved in the aetiology and/or the pathogenesis of midportion Achilles tendinopathy. In addition, a recent innovative surgical procedure for Achilles tendinopathy, which involves excision of plantaris tendon in addition to scraping of the Achilles tendon, has demonstrated good clinical outcomes. 3 Nevertheless, there is a paucity of studies investigating the outcomes of surgery with validated outcome measures. Recently, a novel imaging modality, Ultrasound Tissue Characterisation (UTC), has been used to quantify tendon matrix integrity and has been shown to be reliable and valid 4,5 . Unlike 2D ultrasound and Colour Doppler, UTC objectively quantifies grey-scale tendon matrix changes into 4 different echotypes related to tendon integrity. Namely, type I (green) and II (blue) represents organised matrix; type III (red) and IV (black) represents disorganised matrix. The aim of this study was to investigate the outcomes of an innovative surgical procedure for Achilles tendinopathy including excision of plantaris using validated clinical (VISA-A) and imaging (UTC) outcome measures. Methods In this study, 8 patients and 9 tendons (1 patient with bilateral tendons) with longstanding Achilles pain and 2D ultrasound and UTC findings of plantaris involvement were included. All patients had failed a conservative rehabilitation program. The surgical procedures were performed under local anaesthetic and involved excision of the plantaris tendon located medial to Achilles midportion and scraping of the ventral surface of the Achilles tendon (Figure 1). VISA-A questionnaire and UTC were performed pre- and 6 months post-surgery. UTC was performed on all tendons from calcaneal insertion to musculotendinous junction. Results Seven out of eight patients were satisfied with the procedure. Mean Visa-A score pre-surgery was 56.8 (range from 34 to 73) and 6 months post-surgery was 93.3 (range from 87 to 100). There was a statistically significant increase in mean VISA-A scores after 6 months (t = 1.89, p Conclusion Excision of plantaris tendon in chronic midportion tendinopathy results in improved tendon matrix integrity on UTC. Improvements in tendon structure after plantaris excision could suggest a possible compression mechanism as the main causation for plantaris-associated Achilles tendinopathy. References Van Sterkenburg, et al . J Anat. 2011;218:336–341 Sprang, et al . Histol Histopath . 2013;28:623–632 Van Schie, et al . Br J Sports Med. 2010;44:1153–1159 Alfredson, et al . Br J Sports Med. 2011;45:407–410 Rosengarten, et al . Br J Sports Med. 2015. [Epub ahead of print]

Forty-five cases of canine Achilles mechanism disruption were reviewed, mostly involving medium-sized dogs, among which dobermanns, labradors and border collies were most commonly represented. Most cases were acute in onset (66.7 per cent), and were usually closed injuries (75.6 per cent). In the majority of cases, the damage involved all tendons (26.7 per cent), all tendons except the superficial digital flexor tendon (22.2 per cent), or the gastrocnemius alone (20 per cent). Damage most commonly occurred at the tendo-osseous junction (60 per cent), with injury occurring less commonly at the musculotendinous junction (20 per cent) or in the body of the tendon (13.3 per cent). A plantigrade posture was not predictive of involvement of specific tendons, but was more likely if the injury involved the musculotendinous junction. The most common method of treatment was a primary tendon repair using polydioxanone suture in a locking-loop pattern, with placement of a temporary calcaneotibial screw and cast. The outcome was not significantly influenced by whether the injury was open or closed, the duration of the injury, the tendons involved, or the method of repair. Complications were recorded in 16 cases (35 per cent), of which 10 were minor and six major. Complications were significantly more likely if the damage involved the body of the tendon. Long-term follow-up was available for 19 dogs; the outcome of surgery was considered to be good to excellent in 18 dogs.

A 23-year-old healthy laborer involved in a work-related injury, sustained excessive left ankle plantarflexion, which resulted in closed rupture of the extensor hallucis longus muscle without any predisposing factors. He had an associated fracture of the second metatarsal shaft. The muscle proximal to the musculotendinous junction was excised, and the tendon was looped through a longitudinal slit in the main extensor digitorum communis tendon and sutured to it. The second metatarsal fracture was fixed with Kirschner wires. The patient regained full function and was symptom free 6 months after surgery.

The prevailing dogma in tissue engineering is cell-centric. One shortcoming of this approach is the failure to provide the implanted cells with a suitable in vivo microenvironment that promotes tissue reconstruction. Extracellular matrix (ECM)-based scaffolds provide a three-dimensional microenvironment that can promote constructive and functional tissue remodeling rather than inflammation and scarring even in the absence of any implanted cells. The objective of this study was to determine the ability of an ECM-based scaffold to facilitate functional restoration of the distal gastrocnemius musculotendinous junction in a canine model after complete resection of the tissue. Within 6 months, vascularized, innervated skeletal muscle that was similar to normal muscle tissue had formed at the ECM-scaffold implantation site. This neo-tissue generated 48% of the contractile force of contralateral musculotendinous junction and represents the first report of de novo formation of contractile, vascularized, and innervated skeletal muscle in situ after significant tissue loss.

Muscle injury is common among athletes, and imaging is increasingly being used to confirm injury, to assess its location, extent, and severity, and on occasion to make inferences regarding prognosis and timing of return to sports. Ultrasound and magnetic resonance imaging (MRI) are accurate for diagnosis of acute injuries, but measurements of the extent of injury (cross-sectional area and longitudinal extent of muscle injury adjacent to the musculotendinous junction) have also been shown to correlate with athlete prognosis and recovery time. Specifically, normal MRI studies shortly after injury are associated with rapid (1- to 2-week) recovery and low risk of recurrent injury. Abnormal muscle cross-sectional area >55% is associated with a convalescence interval of >6 weeks, but larger measurements are not clearly associated with higher recurrence risk. The clinical value of follow-up imaging before return to competition is not established, but residual muscle abnormality is often present at this time.

Background An anatomic study specifically investigating the optimal location for proximal biceps tenodesis and detailing the topographic relationship to neurovascular structures has not been conducted. Methods Twelve cadaveric upper extremities were dissected to identify the proximal biceps musculotendinous junction and topographic relationships to neighboring neurovascular structures. Results The musculotendinous junction of the long head of the biceps tendon was on average 2.2 cm distal to the superior border and 3.1 cm proximal from the inferior border of the pectoralis major tendon. The musculocutaneous nerve was on average 2.6 cm medial to the long head of the biceps at the musculotendinous junction. The distance from the lesser tuberosity to the musculotendinous junction of the long head of the biceps averaged 5.4 cm. The distance from the anterior humeral circumflex vessels to the musculotendinous junction of the long head of the biceps was 4.6 cm on average. The distance from the musculotendinous junction of the long head of the biceps to the musculocutaneous nerve as it pierces the coracobrachialis was 4.6 cm. Conclusion In order to restore the appropriate length-tension relationship of the biceps muscle, proximal biceps tenodesis should possibly be placed closer to the superior border of the pectoralis major tendon than previously thought. The lesser tuberosity can be used as a tactile landmark for appropriate intraoperative placement. Although there is a relatively safe “buffer zone” between the location of the tenodesis and adjacent neurovascular structures, extreme caution must be used.

Ultrasound can be used to study tendon and muscle movement. However, quantization is mostly based on manual tracking of anatomical landmarks such as the musculotendinous junction, limiting the applicability to a small number of muscle-tendon units. The aim of this study is to quantify tendon displacement without employing anatomical landmarks, using dedicated speckle tracking in long B-mode image sequences. We devised a dedicated two-dimensional multikernel block-matching scheme with subpixel accuracy to handle large displacements over long sequences. Images were acquired with a Philips iE33 with a 7 MHz linear array and a VisualSonics Vevo 770 using a 40 MHz mechanical probe. We displaced the flexor digitorum superficialis of two pig cadaver forelegs with three different velocities (4,10 and 16 mm/s) over 3 distances (5, 10, 15 mm). As a reference, we manually determined the total displacement of an injected hyperechogenic bullet in the tendons. We automatically tracked tendon parts with and without markers and compared results to the true displacement. Using the iE33, mean tissue displacement underestimations for the three different velocities were 2.5 ± 1.0%, 1.7 ± 1.1% and 0.7 ± 0.4%. Using the Vevo770, mean tissue displacement underestimations were 0.8 ± 1.3%, 0.6 ± 0.3% and 0.6 ± 0.3%. Marker tracking displacement underestimations were only slightly smaller, showing limited tracking drift for non-marker tendon tissue as well as for markers. This study showed that our dedicated speckle tracking can quantify extensive tendon displacement with physiological velocities without anatomical landmarks with good accuracy for different types of ultrasound configurations. This technique allows tracking of a much larger range of muscle-tendon units than by using anatomical landmarks.

This case report describes an unusual second rupture sustained after conservative treatment of an initial Achilles tendon rupture at the musculotendinous junction. The initial injury was successfully managed conservatively with an equinus cast for 6 weeks. The patient developed a tendonitis 10cm below the initial rupture and subsequently sustained a second traumatic rupture of the Achilles tendon at a new site after tripping on a curb. The patient had no known systemic diseases and was not on steroid or fluoroquinolone therapy. The site of this second rupture was repaired surgically using an open technique without any long term complications.

We studied 11 patients with checkrein deformities of the hallux who underwent surgical treatment. Six had lengthening of the flexor hallucis longus tendon by Z-plasty in the midfoot, and five underwent release of adhesions and lengthening of the tendon by Z-plasty at the musculotendinous junction at the fracture site. All six patients who underwent Z-plasty at the midfoot showed complete correction of the deformity without recurrence. Of the five who had release of adhesions and Z-plasty of the tendon at the fracture site, two showed partial and one showed complete recurrence.

OBJECTIVE. The MRI features of the proximal rectus femoris musculotendinous junction have scarcely been described in the literature. The purpose of our study, based on a review of 50 asymptomatic and 20 symptomatic MRI studies, was to define the normal MRI anatomy and MRI features of intrasubstance injury of deep musculotendinous tears of the proximal rectus femoris.CONCLUSION. Axial and coronal MR images are optimal for visualizing the direct and indirect heads, the conjoined tendon, and the deep musculotendinous junction of the proximal rectus femoris. Tears of the deep musculotendinous junction are longitudinal, involving a long segment of the muscle. MRI features include a “bull's-eye” sign, longitudinal scar, retraction, pseudocyst, and hematoma.

A rotator cuff tear causes morphologic changes in rotator cuff muscles and tendons and reduced shoulder strength. The mechanisms by which these changes affect joint strength are not understood. This study's purpose was to empirically determine rotation moment arms for subregions of supraspinatus, infraspinatus, and for teres minor, and to test the hypothesis that subregions of the cuff tendons increase their effective moment arms through connections to other subregions. Tendon excursions were measured for full ranges of rotation on 10 independent glenohumeral specimens with the humerus abducted in the scapular plane at 10 and 608. Supraspinatus and infraspinatus tendons were divided into equal width subregions. Two conditions were tested: tendon divided to the musculotendinous junction, and tendon divided to the insertion on the humerus. Moment arms were determined from tendon excursion via the principle of virtual work. Moment arms for the infraspinatus (p < 0.001) and supraspinatus (p < 0.001) were significantly greater when the tendon was only divided to the musculotendinous junction versus division to the humeral head. Moment arms across subregions of infraspinatus (p < 0.001) and supraspinatus (p < 0.001) were significantly different. A difference in teres minor moment arm was not found for the two cuff tendon conditions. Moment arm differences between muscle subregions and for tendon division conditions have clinical implications. Interaction between cuff regions could explain why some subjects retain strength after a small cuff tear. This finding helps explain why a partial cuff repair may be beneficial when a complete repair is not possible. Data presented here can help differentiate between cuff tear cases that would benefit from cuff repair and cases for which cuff repair might not be as favorable. 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:1737-1744, 2006

We developed a minimally invasive technique for releasing the piriformis muscle under endoscopic control for entrapment neuropathy of the sciatic nerve due to tension and contraction of the piriformis muscle. This is a technical report on minimally invasive arthroscopic release of the piriformis muscle. This surgical technique was performed in patients who fulfilled at least five of nine diagnostic criteria (Fig. 1) that we established and who did not respond to conservative therapy for 6 months or more. While a cavity was maintained using a disposable syringe (10ml) with a cut tip, an arthroscope (4mm in diameter) was inserted at an oblique viewing angle of 30°, and the muscle was identified. The area from the musculotendinous junction to the muscle was gradually incised using a special scraper. Pain disappeared simultaneously with release of the piriformis muscle during operation. In this technique of releasing the piriformis muscle, an adequate cavity can be produced and maintained in a manner similar to that in the posterior endoscopic operation for intervertebral disc herniation. This technique is useful for reducing postoperative pain and allows an early return to society.

Rupture of the triceps brachii at the musculotendinous junction is reported in a patient with diabetes mellitus and hypertension. Successful reconstruction was achieved by delayed primary repair. V-Y advancement of the triceps, and a plantaris tendon graft.

The purpose of this research was to describe the sonographic findings of pectoralis major injuries with clinical, surgical, and magnetic resonance imaging (MRI) correlation.Images from sonographic examinations of the pectoralis major muscle of 6 patients were retrospectively evaluated and characterized. The sonographic findings were compared with clinical, surgical, and MRI findings.The 6 patients were male (mean age, 30 years) with injuries sustained during weight lifting, football, and shotgun firing. Two of the 6 patients had MRI correlation; 1 had surgical correlation; 2 had both surgical and MRI correlation; and 1 had clinical follow-up. The sternal head was injured in 5 patients; 4 involved the musculotendinous junction, and 1 involved the distal tendon. The sonographic findings of muscle fiber retraction and surrounding hemorrhage allowed identification of the affected muscle. Direct impact injury causing hematoma involved the clavicular head in 1 patient. In total, 5 cases were partial-thickness pectoralis major tears, whereas complete distal tendon disruption was found in 1.Sonographic imaging longitudinal to the pectoralis muscle fibers showed fiber disruption, retraction, and possible hypoechoic or anechoic hematoma, most commonly involving the musculotendinous junction of the sternal head. Distal tendon assessment is important to evaluate for a full-thickness pectoralis major tear.

We report a patient with duplicate extensor pollicis longus tendons, who complained of inability to extend the thumb fully because of impingement of the musculotendinous junction of the duplicate tendons. Extension of the thumb recovered completely after Lister's tubercle was excised and the extensor retinaculum was released. Selective windowing with highlighting of the soft tissue in the axial T1-weighted magnetic resonance image at the level of the distal radioulnar joint showed two tendons in the third extensor compartment.

A rare case is presented of a longstanding rupture of the rectus femoris muscle at the proximal musculotendinous junction in a semiprofessional soccer player. Its different and unique presentation, the surgical repair, and the remarkable functional recovery are discussed.

Introduction An inadequate blood supply plays an important role in the development of injuries. It is known that physical activity has an influence on the blood flow of a tendon. However, it remains unclear which type of activity leads to the highest increase in blood flow. Therefore, the aim was to compare the immediate effect of 5 different physical activities (running, stretching, plyometrics, eccentric heel drops, T-test) on the blood flow of the Achilles tendon. Methods Thirty healthy subjects performed each of the 5 activities spread over a period of 3 weeks. Blood flow, saturation and haemoglobin were measured biateral before and after each activity. 12 well-defined tendon points were summarised into 4 regions: insertion, distal midportion, proximal midportion and musculotendinous junction. Changes were statistically analysed using a mixed model analysis. Results At the insertion, running is the only activity which has an immediate effect on the Achilles blood flow (p When compared to the other 4 physical activities, running differs significantly, especially at the insertional region and at the distal midportion. The P-values range from 0.000 to 0.016. In the proximal midportion, running also shows the highest increase and differs significantly from heel drops, stretching and T-test. At the musculotendon unit, only 2 significant P-values are seen; between running and stretching and between running and heel drops. The results of saturation mainly follow those of blood flow whereas the results of haemoglobin are unclear. Discussion The results demonstrate that running implicates the highest increase in blood flow of the Achilles tendon and this throughout the four regions of the Achilles tendon. The present results are in agreement with the observation of a decrease in blood flow after eccentric training and stretching (Knobloch et al., 2007). It is reasonable to assume that due to a tendon stretch the blood vessels within the tendon stretch and become thinner, which results in a slower flow. The higher increase due to running might be explained by the exercising time. The duration of tuck jumps and T-test may not have been sufficient to induce a vasodilation to increase tendon blood flow (Malliaras et al., 2012). In conclusion, if one wants to increase the blood flow of a tendon, it can be recommended to perform physical activities, in which the tendon is loaded cyclically. References Alfredson H, et al. Knee Surg Sports Traumatol Arthrosc, 2006;14:399–401 Boesen MI, et al. Am J Sports Med. 2006;34(12):2013–2021 Boesen MI, et al. Scand J Med Sci Sports. 2006;16(6):463–469 Boesen AP, et al. Am J Sports Med. 2012;40(3):548–555 Fahlstrom M, et al. Br J Sports Med. 2010;44:140–143 Hirschmuller A, et al, Med Sci Sports Exerc. 2012;44(2):199–205 Kjaer M, et al., Scand J Med Sci Sports. 2000;10(6):326–331 Knobloch K, et al. Am J Sports Med. 2006;34(1):92–97 Knobloch K, et al. J Orthop Sports Phys Ther. 2007;37(5):269–276 Kubo K, et al. Acta Physiol (Oxf). 2008;193(3):257–264 Langberg H, et al. Eur J Appl Physiol. 2001;84(3):246–248 Mahieu N, et al. Int J Sports Med. 2010;31(12):901–5 Malliaras P, et al, Am J Sports med. 2008;36(11):2210–2215 Malliaras P, et al. Int J Sports med. 2012;33:480–484 Ohberg L, et al. Knee Surg Sports Traumatol Arthrosc. 2004;12(5):465–470 Reiter M, et al. Int J Sports Med. 2004;25(4):301–305 Van Snellenberg W, et al. Scand J Med Sci Sports. 2007;17(5):530–534

Purpose: To (1) better define the anatomy of the proximal shoulder in relation to the long head of the biceps tendon, (2) compare the length-tension relationship of the biceps tendon in the native shoulder with that after arthroscopic and open tenodesis techniques using interference screws, and (3) provide surgical recommendations for both procedures based on study findings. Study Design: Descriptive laboratory study. Methods: Twenty fresh-frozen cadaveric shoulders were dissected for analysis. Initial anatomic measurements involving the proximal long head of the biceps tendon (BT) were made, which included: the labral origin to the superior bicipital groove (LO-SBG), the total tendon length (TTL), the musculotendinous junction (MTJ) to the inferior pectoralis major tendon border, the MTJ to the superior pectoralis major tendon border, and the biceps tendon diameter (BTD) at 2 different tenodesis locations. These same measurements were made again after completing a simulated suprapectoral arthroscopic and open subpectoral tenodesis, both with interference screw fixation. Statistical comparisons were then made between the native anatomy and that after tenodesis, with the goal of assessing the accuracy of re-establishing the normal length-tension relationship of the long head of the BT after simulated arthroscopic suprapectoral and open subpectoral tenodesis with tenodesis screws. Results: For all cadavers, the mean TTL was 104.1 mm. For the arthroscopic suprapectoral technique, the mean LO-SBG was 33.6 mm, and the mean tendon resection length was 12.8 mm in males and 5.0 mm in females. The mean BTD was 6.35 mm at the arthroscopic suprapectoral tenodesis site and 5.75 mm at the open subpectoral tenodesis site. Males were found to have statistically longer TTL and LO-SBG measurements (111.6 vs 96.5 mm [ P = .027] and 37.2 vs 30.0 mm [ P = .009], respectively). In the native shoulder, the mean distances from the MTJ to the superior and inferior borders of the pectoralis major tendon were 23.8 and 31.7 mm, respectively. No statistically significant differences were found in the location of the MTJ after simulated arthroscopic or open tenodesis with tenodesis screws as compared with the native shoulder. Mean hole depth in the open subpectoralis tenodesis was 22.4 mm (males) and 18.6 mm (females), with a mean of 20.5 mm for both sexes. Conclusion: This study better defines the anatomy of the proximal shoulder in relationship to the long head of the BT. Using our surgical techniques and recommendations, both arthroscopic and open tenodesis procedures adequately restored the native length-tension relationship of the long head of the biceps. Surgical recommendations are as follows: For arthroscopic suprapectoral tenodesis with tenodesis screws, the anatomic landmark of the SBG should be used. The tendon resection length should be approximately 1 cm in males and 5 mm in females when using a 25-mm tunnel. For subpectoral tenodesis, the site of tenodesis should be placed approximately 3 cm above the inferior border of the pectoralis major tendon in the bicipital groove; whipstitching and preserving approximately 2 cm of the biceps tendon above the MTJ is also recommended. The diameter of the screws in either location should be based on patient anatomy. However, this study shows the need for slightly longer screws for the subpectoral tenodesis, as the average hole depth was 20.5 mm. The system used in this study has 7 × 10–mm and 8 × 12–mm screws available. Based on study findings, a screw length of 15 to 18 mm may be needed.

The brachioradialis muscle is a common donor in tetraplegia reconstruction. The purpose of this study was to determine the available excursion of the brachioradialis during graduated release of its insertion sites. Fourteen extremities in 10 patients with cervical spine injuries underwent surgical reconstruction for restoration of hand function using the brachioradialis as a donor for one of the restored movements. At the time of surgery the brachioradialis was exposed along the forearm and a wire was inserted into the muscle followed by excitation with a biphasic, asymmetrical, charge-balanced waveform. A 12-Hz frequency and 20-mA current were used to stimulate the muscle while the pulse duration was varied between 0 and 200 milliseconds to achieve maximum contraction. Average brachioradialis excursion after incision of the radial styloid insertion site was 8 mm and 14 mm after mobilization to the musculotendinous junction. Further release of the fascial connections and mobilization of the muscle belly increased the excursion to an average of 61 mm. The increase in excursion after fascial release and muscle mobilization was significant and should be performed to obtain maximum available excursion.

To evaluate the sonographic appearance of the peroneus quartus muscle.Thirty-two consecutive patients who underwent both sonography and magnetic resonance (MR) imaging of the lateral ankle were retrospectively identified during 42 months. Seven of these patients demonstrated a peroneus quartus muscle, with MR imaging as the standard of reference. The peroneus quartus muscle was characterized at retrospective review of sonographic images with regard to origin, insertion, echogenicity, and location.Of the seven peroneus quartus muscles, six originated from the peroneus brevis muscle, and all seven inserted onto the calcaneus. The muscle portion of the peroneus quartus muscle was hypoechoic, while the tendon portion was hyperechoic and fibrillar. The location of the peroneus quartus musculotendinous junction was variable. Hence, the appearance of the peroneus quartus muscle in the region of the distal fibula ranged from 100% muscle to 100% tendon.Variability in the appearance of the peroneus quartus muscle is common with sonography due to variation in the location of the musculotendinous junction. Recognition of these variations will allow correct diagnosis of a peroneus quartus muscle, and more important, it will allow differentiation from adjacent tendon abnormality.

Although hamstring injuries are common in athletes, the distribution and location of such injuries have not been well defined. We used MR imaging to determine the frequency of injury by muscle, involvement of one or more muscles, and location of injuries within the musculotendinous unit.We performed MR imaging on 15 consecutive college athletes with clinically diagnosed acute hamstring injuries. A hamstring injury was diagnosed and located on MR imaging by identifying high signal intensity within the muscle on T2-weighted images.We found that 10 athletes had injuries of a single muscle with six injuries of the biceps femoris, three of the semitendinosus, and one of the semimembranosus. In an additional five athletes, we found primary injuries of the biceps femoris and secondary injuries of the semitendinosus. The injuries occurred in diverse locations within the muscles including five injuries at the proximal musculotendinous junction, two at the distal musculotendinous junction, four within the proximal half of the muscle belly, and four in the distal half. All eight intramuscular injuries were located at the musculotendinous junction within the muscle.The biceps femoris is the most commonly injured hamstring muscle and the semitendinosus is the second most commonly injured. Although hamstring injuries often involve one muscle injured proximally, multiple muscles were involved in 33% of athletes (5/15) and the injuries were distal in 40% of athletes (6/15). All intramuscular injuries occurred at the musculotendinous junction, either at the ends of the muscle or within the muscle belly.

Muscle injuries are common, with an incidence varying from 10% to 55% of all injuries sustained in sports (Lehto and Jarvinen 1991). Muscle injuries are divided into 2 types: a shearing injury, in which both the myofibers and the connective tissue framework are torn, or an in situ injury, in which only the myofibers are damaged and the basal lamina and connective tissue sheaths do not undergo significant harm. Shearing injuries, the most frequent muscle injuries related to sports, may be lacerations, contusions, or strains, depending on the mechanism of injury (Lehto and Jarvinen 1991). Contusion is sustained through a significant compressive force to the muscle, such as a direct blow, a common occurrence in contact sports. A strain occurs when a forceful eccentric contraction is applied to an overstretched muscle, especially in jumping or sprinting (Garrett, Jr. 1990; Lehto and Jarvinen 1991). Injury is common near the musculotendinous junction (MTJ) of a superficial muscle that crosses 2 joints, such as the rectus femoris, semitendinosus, and gastrocnemius muscles. Though rather rare in sports, muscle laceration is a dramatic injury that consistently incapacitates athletes for long periods of time and often jeopardizes their professional careers.

Traumatic rupture of the flexor tendons at the musculotendinous junction is rare. A case of flexor pollicis longus tendon rupture at the musculotendinous junction is described. The mechanism of the tendon injury appears to be longitudinal traction on the contracted muscle during delivery of a bowling ball.

Objective: To describe the various morphologic appearances of endplate spikes, define the theoretical volume conduction basis of these waveforms' morphologies, and simulate "atypical" endplate spike waveforms documented by other investigators. Design: Endplate spikes were recorded from the biceps brachii in healthy individuals using a monopolar needle electrode. The morphologies of these waveforms were compared with those obtained from a computer simulation. Previously documented endplate waveforms were simulated using two fundamental types of biphasic initially negative and positive waveform morphologies. Setting: University clinic outpatient electrodiagnostic medicine facility. Subjects: Five subjects without history or physical evidence of neuromuscular disease. Main Outcome Measures: Endplate potential morphologies were assessed with respect to overall waveform shape and number of phases. Computer-generated waveforms for individual endplate spike waveforms were qualitatively compared with those recorded from the subjects. Results: Three fundamental waveforms were documented to arise from the endplate regions of all subjects and were successfully simulated: (1) biphasic initially negative potential from the endplate itself and up to 0.2mm from the endplate, (2) triphasic initially positive potential from within 0.2mm of the endplate up to 0.5mm from the musculotendinous junction, and (3) biphasic initially positive potential from the last 0.4mm of the fiber or from impulse blocking. Two biphasic endplate spike waveforms could be summated to generate all other endplate waveforms described in previously documented literature. Conclusion: The combination of clinical and simulation studies suggests that endplate spike potentials can have quite varied morphologies. Triphasic initially positive and biphasic initially positive endplate spikes may be mistaken for fibrillation potentials and positive sharp waves, respectively. The triphasic waveforms most likely arise from an action potential propagating past the recording electrode adjacent to the end-plate, while the biphasic initially positive potential is simulated to arise from the needle electrode blocking action potential propagation.

Although it is recognized as the muscle flap of choice for middle-third defects of the lower limb, the capability for even more distal transposition of the soleus muscle remains controversial. Such reach depends directly on the site of insertion of the muscle and previously has not been assessed convincingly without surgical intervention. Magnetic resonance imaging (MRI) may be a noninvasive alternative for determining the distal extent of the musculotendinous junction of the soleus muscle. In our last four patients, preoperative MRI scans were obtained prior to an elective soleus muscle transfer. The distance from the ankle joint to the most distal site of the soleus insertion was measured on the MRI scan and compared with the actual intraoperative measurement, which had a significant correlation (r = 0.98, p = 0.019). A retrospective review of 42 other sagittal ankle MRI scans predicted the mean of this distance to be 1.92 +/- 1.23 cm (range -0.4 to 4.5 cm), compared with gross anatomic dissections in 30 unrelated fresh cadavers, where this was 4.06 +/- 3.11 cm (range -0.7 to 12.5 cm). These additional data are pertinent because they reinforce recognition of the great variation in soleus anatomy, which would limit clinical applications for the distal third of the leg only for those individuals with very distal insertions. The MRI scan can reliably identify the soleus muscle and provides a nonoperative method for evaluation of potential feasibility for its use as a local muscle flap for distal lower extremity defects.

A low-lying belly of the musculus peroneus brevis (presence of muscle tissue within the fibular groove) is said to be a risk factor for rupture or dislocation of the peroneal tendons. However, alterations in foot position may affect the position of the musculotendinous junction. The purpose of this study was to evaluate the normal position of the musculotendinous junction of the musculus peroneus brevis in full dorsiflexion and plantar flexion.The ankles of 12 adult asymptomatic volunteers were imaged in full dorsiflexion and plantar flexion. The number of scans between the fibular groove and the first scan imaging the muscle belly of the musculus peroneus brevis was documented in each patient in full dorsiflexion and plantar flexion.Distal extension of muscle belly into or beyond the fibular groove was present in 11 subjects in dorsiflexion and in seven subjects in plantar flexion.Extension of the muscle belly of musculus peroneus brevis into and distal to the fibular groove is part of the normal excursion of the muscle during foot motion. Care should be taken not to misdiagnose this normal finding as a pathologic condition when interpreting MR studies of the ankle.

Each of the fingers has a flexor digitorum sublimis tendon and a flexor digitorum profundus tendon. The flexor digitorum profundus tendons have a common muscle belly and are interconnected at the musculotendinous junction, thereby restricting independent profundus excursion, resulting in combined motion of all four profundus tendons with the so-called quadrigia effect. The blood supply to the flexor tendons is obtained from the dorsal side of the tendons through the vinculae. Core sutures used in the repair of lacerated tendons should be placed in the palmar half of the tendon to help preserve the dorsal blood supply. Although at one time it was recommended not to repair both tendons and, in fact, occasionally to excise the stump of the sublimis, it is now generally accepted that the appropriate treatment should be repair of both tendons. This has the advantage of maintaining the vincula system and, therefore, the blood supply to the tendons (Fig. 3–1).

The tensile failures of extensor digitorum longus muscle tendon units from 16 male New Zealand White rabbits were studied in the fresh state (less than 30 minutes after death) and in the frozen/thawed state (frozen at -80 degrees C for 28 days and then warmed to 38 degrees C). Frozen/thawed extensor digitorum longus muscle tendon units had significantly lower values for load to failure (p < 0.01), energy absorbed to failure (p < 0.01), and strain at failure (p < 0.01), and they tended to fail at a different anatomic location (p < 0.01) (broadly at the fascia-muscle interface as compared with horizontally at the musculotendinous junction) than fresh units. The results of this study suggest that freezing muscle tendon units significantly alters their tensile failure characteristics.

The tensile properties of the extensor digitorum longus muscle tendon unit (EDL MTU) were studied in 16 white male New Zealand rabbits in the freshly euthanized state (less than 30 minutes after death) and the frozen-thawed state (frozen at -80 deg C for 28 days and then warmed to 38 deg C) Stretch to failure was specifically analyzed. Frozen thawed EDL MTUs had significantly lower ultimate force to failure (p

Introduction Rupture 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 presentation A 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. Conclusion For 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.

Traumatic, subcutaneous ruptures of flexor tendons in the hand are infrequent findings in clinical practice. They usually occur at the bony insertion or at the musculotendinous junction. Intratendinous ruptures are reported almost only in association with underlying pathologic conditions. We report a case of subcutaneous rupture through the healthy substance of the profundus flexor tendon of the small finger in the palm of the hand, which was associated with a complete tendinous fusion between the deep flexor of the ring and small finger up to the lumbrical insertion.

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.

A case is presented of a bifid median nerve whose longest portion had a normal course while the other portion passed through a hole in the FDS tendon of the middle finger, at its musculotendinous junction. This caused nerve compression during muscle contraction, producing pain and dysaesthesia in the middle finger suggesting carpal tunnel syndrome.