The soleus muscle: MRI, anatomic and histologic findings in cadavers with clinical correlation of strain injury distribution

Objective

The purpose of this study was to describe the normal anatomy of the soleus muscle using Magnetic Resonance (MR) imaging, anatomic dissection and histologic correlation in cadavers. The second objective of this study was to analyse the morphometry of the soleus muscle in normal volunteers. The final objective was to undertake a retrospective review of soleal strain injuries confirmed with MR imaging, with correlation made between the cadaveric anatomic findings and the MR imaging features.

Materials and methods

Eleven fresh cadaveric legs were studied using a high resolution 3.0 T (T) MR imaging scanner to obtain images in the axial, coronal and sagittal planes. After imaging, six specimens were dissected and evaluated by histological analysis, with the remaining five specimens then frozen and cut into axial sections. The corresponding levels on the MR examination were then compared with the levels of anatomic sectioning. MR imaging was also used to examine the soleus muscle in both legs of 20 healthy volunteers. Finally, 55 clinical cases of soleus muscle strains diagnosed between October 2006 and January 2011 that had also previously undergone MR imaging were re-evaluated. The location of strain injury was reviewed and correlated with the anatomic information that had been revealed in the anatomic component of our study.

Results

Dissection of the soleus muscle revealed two proximal intramuscular aponeuroses (medial and lateral) that are formed as a direct continuation of the surrounding epimysium. From an anatomic, functional and pathologic perspective, these aponeuroses are considered in this study as intramuscular tendons, however they have been not previously described as such. These tendons penetrate deep into the muscle belly, from which the proximal muscle fibres of the soleus arise. Inferiorly, these muscle fibres insert onto a long distal central tendon that becomes confluent with the overlying distal tendon of gastrocnemius to form the Achilles tendon. Significant differences between the length of the central tendon on the right side (31.35 cm) and the left side (30.36 cm) were observed (p?=?.002), as well as the length of insertion of this tendon onto the Achilles tendon on the right side (7.19 cm) compared with the left (7.94 cm) (p?=?.02). The retrospective analysis identified five sites within the soleus where strains were distributed: musculotendinous junction sites (proximal medial strains accounting for 25.5 % of all injuries, proximal lateral strains accounting for 12.7 % and distal central tendon strains accounting for 18.2 %) and myofascial sites (anterior strains accounting for 21.8 % of all injuries and posterior strains accounting for 21.8 %). Strains of the proximal medial musculotendinous junction were the most common of soleal muscle injuries, comprising 56.4 % of all cases.

Conclusion

Current information on the detailed anatomy of the soleus muscle in the anatomic and radiological literature is lacking. Knowledge of this anatomy accounts for the distribution of sports-induced injuries within the soleus muscle-tendon unit and therefore assists in the accurate identification of these injuries, with possible prognostic benefit.     

Imaging of plantar fascia and Achilles injuries undertaken at the London 2012 Olympics

Plantar fascia and distal Achilles injuries are common in elite athletes. Acute athletic injuries of the plantar fascia include acute plantar fasciopathy and partial or complete tears. Underlying most acute injuries is a background of underlying chronic plantar fasciopathy. Injuries may affect the central or less commonly lateral portions of the fascia and acute tears are generally proximal. Athletic Achilles injuries may occur at the mid tendon or the distal insertion, and there may be an underlying chronic tendinopathy. Acute or chronic paratendinopathy may occur as a separate entity or combined with Achilles injury. In this article, the spectrum of athletic injuries of the plantar fascia and Achilles is described, illustrated by imaging findings from the London 2012 Olympic games.     

Stretch training induces unequal adaptation in muscle fascicles and thickness in medial and lateral gastrocnemii

This study compared adaptations in fascicle lengths, pennation angles, and muscle thickness of the lateral and medial gastrocnemii in response to 6 weeks of stretch training. The nondominant plantar flexors of 11 males were stretched five times per week for 6 weeks and compared with the contralateral leg and a nonstretched control group of 10 males. During stretch training, instantaneous electromyography was utilized to ensure passive muscle stretch. At baseline, week three, week six and 1 week after the conclusion of stretch training, ultrasound was used to measure fascicle lengths, pennation angles, muscle thickness of the lateral gastrocnemius and medial gastrocnemius, and Achilles tendon thickness and length. Plantar flexion torque was measured, and voluntary activation was assessed. Muscle thickness increased 5.6% after 6 weeks of stretch training (P=.009). The fascicles in the lateral gastrocnemius lengthened to a greater extent than the medial. Overall, fascicles lengthened 25% (P<.001) in the muscle tendon junction and 5.1% (P<.001) in the muscle belly. Pennation angles were unchanged in the medial gastrocnemius but decreased in the lateral gastrocnemius 7.1% (P=.02). There was no change in maximal voluntary contraction, voluntary activation, tendon length, or thickness. This study demonstrates that stretch training is a viable modality to alter muscle architecture of the human gastrocnemius through lengthening of muscle fascicles, decreasing pennation angles, and increasing muscle thickness, albeit adaptations are unequal between the lateral and medial heads.     

Pectoralis major muscle and tendon tears: diagnosis and grading using magnetic resonance imaging

 Objective. To assess the accuracy and utility of magnetic resonance (MR) imaging in the detection and grading of pectoralis major muscle and tendon tears. Design and patients. A retrospective review was carried out of 10 patients referred for MR imaging for suspected pectoralis muscle injury and possible operative therapy. The pectoralis muscle and tendon were imaged using thin (3–4 mm) axial sections with a variety of sequences combined for anatomical delineation (T1-weighted SE or PD SE) and fluid detection (T2-weighted SE, T2-weighted FSE with fat suppression, or STIR). Surgical correlation was available in six patients. Clinical follow-up was available in four patients treated by nonoperative therapy. Results. MR imaging identified five complete tears, four partial tears and one normal tendon. One complete and one partial tear were at the myotendinous junction. The remaining seven injuries were at the enthesis. Surgical correlation consisted of five complete tears and one partial tear. One complete and one partial tear were at the myotendinous junction with the remaining four complete tears at the enthesis. The MR interpretation and surgical findings were in agreement in all six cases. All four patients treated with nonoperative therapy demonstrated improvement at a clinical follow-up examination, with restoration of function and strength consistent with a healed prior partial injury. Conclusion. MR imaging is accurate and useful in detecting and grading tears involving the pectoralis major muscle and tendon, facilitating the identification of patients with complete tears who are candidates for operative therapy. Received: 7 June 1999 Revision requested: 22 June 1999 Revision received: 16 February 2000 Accepted: 21 February 2000     

Diagnosis of popliteus injuries with MR imaging

Objective. Popliteal muscle and tendon injuries are thought to be unusual. This report describes the magnetic resonance (MR) appearances of popliteus muscle and tendon injuries. Design and patients. The study included 24 patients where the diagnoses of popliteal injuries were prospectively made based on MR appearances. The study group was taken from 2412 consecutive knee MRIs. The injuries were characterized as to involving the muscular or tendinous portions of the popliteus apparatus. Results. In 95.8% (23/24) of patients, the tears of the popliteus involved the muscular portion. The injuries were either partial and interstitial or complete. Three patients had tears of both the muscular and tendinous portions or the tendon alone. The anterior and posterior cruciate ligaments were torn in 16.7% (4/24) and 29.2% (7/24) of patients, respectively. There were medial and lateral meniscal tears in 45.8% (11/24) and 25% (6/24) of patients, respectively. There were injuries of the medial and lateral collateral ligaments in 8.3% (2/24) and 4.2% (1/24) of patients, respectively. Bone bruises and/or fractures were seen in 33.3% (8/24) patients. In 8.3% (2/24) of patients, the popliteus injury was an isolated finding. Conclusion. Popliteus muscle and tendon injuries are not uncommon. They usually occur in conjunction with other significant injuries of the knee and can be characterized with MR imaging.Presented at RSNA, Chicago, Illinois, December 1992     

Magnetic resonance imaging findings of injuries to the calf muscle complex

Objective The objective was to describe the imaging findings following acute injury to the calf musculature. Design and patients We retrospectively reviewed 59 MR examinations in patients who sustained injuries to the calf muscle from April 2001 to September 2004 (48 men, 11 women), with an average age of 31 and 47 years respectively (range in men 20–53; range in women 33–63). Attention was directed to the frequency of muscle involvement, the location of the injury within the musculotendinous unit and the extent of the injury. Results and conclusions A total of 79 separate sites of strain injury were identified (39 solitary, 20 dual). Of the 39 isolated strains, injury to the gastrocnemius was most common (19 out of 39; 48.7%), preferentially involving the medial head in 18 cases and the lateral head in 1 case. The soleus was also commonly involved (18 out of 39; 46.2%), with 2 cases (5.1%) of distal avulsions of the plantaris. Of the 20 dual injuries, a combination of gastrocnemius injury with soleus injury was the most frequent finding (12 out of 20; 60%). Dual injuries of both heads of the gastrocnemius muscles were demonstrated in 4 cases (20%), with the soleus and tibialis posterior injured in 3 cases (15%). A combination of soleus and flexor hallucis longus injury was seen in 1 case (5%). Conclusion This retrospective study utilizing MRI demonstrates that the medial head of the gastrocnemius is the most commonly injured muscle of the calf, closely followed by the soleus, the latter finding rarely reported in the sonographic literature. Dual injuries of the calf muscle complex occur much more commonly than previously reported and may be of prognostic significance.     

Stun gun induced myotendinous injury of the iliopsoas and gluteus minimus

We report a 57-year-old man with a complete tear of his iliopsoas tendon at the distal myotendinous junction, a near complete tear of the iliopsoas tendon at the lesser trochanter of the femur, and a high-grade tear of his gluteus minimus tendon at the greater trochanter of the femur after being struck by a stun gun in the proximal left thigh. The stun gun discharge resulted in a forced contraction of the left hip flexor muscles, which resulted in pain, weakness and difficulty with active hip flexion. Three months after the being struck with the stun gun, the patient underwent magnetic resonance imaging (MRI) of the left hip. MRI of the left hip revealed a complete tear of the left iliopsoas tendon from the lesser trochanter with 4 cm of proximal retraction and a high-grade strain of the gluteus minimus tendon at the greater trochanter. The distal iliopsoas myotendinous junction and lesser trochanter tendon insertion were surgically repaired. This case illustrates that a stun gun can cause acute rupture of the iliopsoas tendon and tear of the gluteus minimus tendon, which is well visualized on MRI.     

Characteristics of acute groin injuries in the adductor muscles: A detailed MRI study in athletes

Acute adductor injuries account for the majority of acute groin injuries; however, little is known about specific injury characteristics, which could be important for the understanding of etiology and management of these injuries. The study aim was to describe acute adductor injuries in athletes using magnetic resonance imaging (MRI ). Male athletes with acute groin pain and an MRI confirmed acute adductor muscle injury were prospectively included. MRI was performed within 7 days of injury using a standardized protocol and a reliable assessment approach. 156 athletes presented with acute groin pain of which 71 athletes were included, median age 27 years (range 18‐37). There were 46 isolated muscle injuries and 25 athletes with multiple adductor injuries. In total, 111 acute adductor muscle injuries were recorded; 62 adductor longus, 18 adductor brevis, 17 pectineus, 9 obturator externus, 4 gracilis, and 1 adductor magnus injury. Adductor longus injuries occurred at three main injury locations; proximal insertion (26%), intramuscular musculo‐tendinous junction (MTJ ) of the proximal tendon (26%) and the MTJ of the distal tendon (37%). Intramuscular tendon injury was seen in one case. At the proximal insertion, 12 of 16 injuries were complete avulsions. This study shows that acute adductor injuries generally occur in isolation from other muscle groups. Adductor longus is the most frequently injured muscle in isolation and in combination with other adductor muscle injuries. Three characteristic adductor longus injury locations were observed on MRI , with avulsion injuries accounting for three‐quarters of injuries at the proximal insertion, and intramuscular tendon injury was uncommon.     

Functional anatomy of the Achilles tendon

The Achilles tendon is the strongest and thickest tendon in the human body. It is also the commonest tendon to rupture. It begins near the middle of the calf and is the conjoint tendon of the gastrocnemius and soleus muscles. The relative contribution of the two muscles to the tendon varies. Spiralisation of the fibres of the tendon produces an area of concentrated stress and confers a mechanical advantage. The calcaneal insertion is specialised and designed to aid the dissipation of stress from the tendon to the calcaneum. The insertion is crescent shaped and has significant medial and lateral projections. The blood supply of the tendon is from the musculotendinous junction, vessels in surrounding connective tissue and the osteotendinous junction. The vascular territories can be classified simply in three, with the midsection supplied by the peroneal artery, and the proximal and distal sections supplied by the posterior tibial artery. This leaves a relatively hypovascular area in the mid-portion of the tendon where most problems occur. The Achilles tendon derives its innervation from the sural nerve with a smaller supply from the tibial nerve. Tenocytes produce type I collagen and form 90% of the cellular component of the normal tendon. Evidence suggests ruptured or pathological tendon produce more type III collagen, which may affect the tensile strength of the tendon. Direct measurements of forces reveal loading in the Achilles tendon as high as 9 KN during running, which is up to 12.5 times body weight.     

Injuries of the pectoralis major muscle: evaluation with MR imaging

PURPOSE: To demonstrate that magnetic resonance (MR) imaging allows evaluation of injuries of the pectoralis major muscle. MATERIALS AND METHODS: Fifteen men underwent MR imaging after injury of the pectoralis major muscle. Most of the patients (nine of 15) were injured while lifting weights, notably bench-pressing. The injuries were evaluated for abnormal morphology and signal intensity, specifically the site of injury, degree of tearing, and amount of tendon retraction. RESULTS: Six injuries occurred at the musculotendinous junction, and five were treated conservatively; eight of the nine cases of distal tendon avulsion were treated with primary surgical repair. The MR imaging findings were confirmed in the nine cases treated surgically. Complete tears (three of 15) were less common than partial tears (12 of 15). The sternal and clavicular heads were torn in 10 patients, only the clavicular head was torn in two patients, and only the sternal head was torn in three patients. Acute tears (10 of 15) demonstrated hemorrhage and edema, whereas chronic tears (five of 15) demonstrated fibrosis and scarring. There was a variable amount of tendon retraction. CONCLUSION: MR imaging allows accurate evaluation of injuries of the pectoralis major muscle and enables identification of patients who would benefit from surgical repair.     

Posterolateral complex knee injuries: magnetic resonance imaging with surgical correlation

Purpose: To describe the magnetic resonance imaging (MRI) findings of injuries of the posterolateral aspect of the knee and to evaluate the diagnostic capabilities of MRI in the assessment of these injuries.

Material and Methods: The MRI studies of 14 patients (mean age 33 years) with trauma to the posterolateral aspect of the knee were retrospectively reviewed, and the imaging findings were correlated with those of surgery.

Results: In all patients, MRI showed an intact iliotibial (ITB) band. MRI showed injury to the biceps tendon in 11 (79%), the gastrocnemius tendon in 1 (7%), the popliteus tendon in 5 (36%), and the lateral collateral ligament (LCL) in 14 (100%) patients. Tear of the anterior cruciate ligament (ACL) was seen in 11 (79%) patients and tear of the posterior cruciate ligament (PCL) in 4 (29%) patients. With routine MRI, visualization of the popliteofibular or fabellofibular ligaments was incomplete. On MRI, the lateral meniscus and the medial meniscus were torn with equal frequency (n = 4; 29%). Osteochondral defects were seen in 5 (36%) cases and joint effusion in all 14 (100%) cases on MRI. Using surgical findings as the standard for diagnosis, MRI proved 86% accurate in the detection of injury to the ITB band, the biceps tendon (93%),, the gastrocnemius tendon (100%), the popliteus tendon (86%), the LCL (100%), the ACL (79%), the PCL (86%), the lateral meniscus (90%), the medial meniscus (82%), and the osteochondral structures (79%). Surgical correlation confirmed the MRI findings of joint effusion in all cases.

Conclusion: MRI is well suited for demonstrating the presence and extent of injuries of the major structures of the posterolateral complex of the knee, allowing characterization of the severity of injury.     

Iliopsoas injury: an MRI study of patterns and prevalence correlated with clinical findings

OBJECTIVES: The objective was to retrospectively determine the prevalence and patterns of iliopsoas injuries based on consecutive MRI examinations, correlated with clinical findings. MATERIALS AND METHODS: From 4,862 consecutive MRI examinations of the hips and pelvis, 32 patients with 33 iliopsoas injuries were identified and graded as muscle strain, partial tendon tear, and complete tendon tears. These patients' medical records were reviewed to determine age, gender, and cause of symptoms. RESULTS: The prevalence of iliopsoas tendon and myotendinous injuries was 0.66% (95% CI: 0.44-0.89). There were 18 females and 14 males whose ages ranged from 7 to 95 years (mean, 54 years). The most frequent presenting symptom was hip pain and the most frequent clinical diagnosis, an occult fracture. The most common injuries in patients under 65 years (16 patients) were muscle strains and partial tendon tears, most often due to an athletic injury. The most common injury in patients 65 years and older (16 patients) was a complete tear (8 patients, all females), 2 of which were spontaneous in origin. CONCLUSIONS: Each grade of iliopsoas injury occurred with similar frequency. The more advanced the age of the patient, the more severe the injury. Non-athletic injuries predominated in patients 65 years and older; athletic injuries were the most common cause of iliopsoas injury in patients under 65 years.     

Ultrasound demonstration of distal triceps tendon tears

Purpose

Rupture of the distal triceps tendon is an uncommon injury that may be unrecognized on clinical examination. The purpose of the study is to describe the role of US in distal triceps tendon tears evaluation.

Materials and methods

IRB approval was obtained and patients gave written informed consent. Of 77 consecutive US examinations of the elbow obtained over a five-year period, eight patients with correlative MR and surgery available were identified having partial or complete distal triceps tendon tear.

Results

N = 4 complete tears of the triceps tendon and n = 4 partial tears of the distal triceps involving the lateral/superficial head were identified. Patients with partial tear had a history of a single traumatic event that determined a sudden eccentric contraction of the triceps muscle against resistance. US demonstrated on axial and longitudinal planes a partial tear of the triceps brachii tendon that resulted in a fusiform swelling and retraction of the lateral/superficial head in four patients. It was possible to identify the normal insertion of the medial head of the triceps moving the transducer medially. MR and surgical findings were concordant with US findings in every patient.

Conclusion

Ultrasound is able to differentiate complete from partial triceps tendon tears. US has the potential to identify isolated lesions of the lateral/superficial head of the triceps with an intact medial head.     

Partial rupture of the proximal Achilles tendon: a differential diagnostic problem in ultrasound imaging

Objectives: The aim of this study was to determine whether ultrasound can correctly visualise partial ruptures of the proximal Achilles tendon. Method: This was a prospective study in which all chronic Achilles tendon injury patients seen at three centres in Germany from 1998 to 2003 were screened. All patients with clinical and/or sonographic signs of abnormalities in the region of the proximal third of the Achilles tendon and tendomuscular junction were included in the analysis. Each of these cases was evaluated by ultrasound following an assessment protocol. Patients with ambiguous ultrasound findings and/or clinical signs were additionally assessed by magnetic resonance imaging (MRI). Results: Sonomorphologic changes suggestive of an abnormality in the proximal third of the Achilles tendon were detected in 13 out of 320 patients (4.2%) with recurring Achilles tendon complaints. Thirteen patients had clinical signs but no sonographic changes in the tendon. The sonographic diagnosis was correct in 19 cases. In six of the 26 cases studied, MRI was needed to establish the correct diagnosis of partial intratendinous rupture of the proximal Achilles tendon. Sensitivity was 0.5, specificity was 0.81, and the overall agreement of the ultrasound examination was 61.5%. All patients were asymptomatic at follow up at a mean of 14 months (range 12–17 months) after surgery. Conclusions: Ultrasound is a useful tool for evaluation of proximal Achilles tendon complaints. However, ultrasound is not sufficiently reliable for diagnosis of all pathologies, especially partial ruptures of the Achilles tendon. Thus, the definitive diagnosis must be established by MRI.     

MRI diagnosis of contracture of the gluteus maximus muscle

OBJECTIVE: The objective of our study was to describe MRI features of contracture of the gluteus maximus muscle after providing a retrospective review of the MRI studies of 21 patients. CONCLUSION: Gluteal contracture manifests characteristic features on MRI, including an intramuscular fibrotic cord extending to the thickened distal tendon with atrophy of the gluteus maximus muscle and posteromedial displacement of the iliotibial tract. In advanced cases, medial retraction of the muscle and its tendon results in a depressed groove at the muscle-tendon junction and external rotation of the proximal femur. Clinical correlation and meticulous physical examination may confirm the MR diagnosis.     

Sonographic and MRI appearance of tensor fasciae suralis muscle,an uncommon cause of popliteal swelling

A 20-year-old white man presented with a localized unilateral swelling in the popliteal fossa. Ultrasound (US) showed the presence of an accessory muscle, the tensor fasciae suralis. The muscle was located in the proximal portion of the popliteal fossa, superficial to the medial head of the gastrocnemius. Its long tendon extended inferiorly to join the Achilles tendon. Magnetic resonance images correlated well with the US findings, confirming the diagnosis. Tensor fasciae suralis muscle is a rare cause of popliteal swelling and must be differentiated from other masses. Both US and magnetic resonance imaging can diagnose it but we suggest US as the first-line technique in its evaluation.     

Long-term results after surgical management of partial Achilles tendon ruptures

Although Achilles tendon injuries are common overuse injuries in sports, the exact incidence is unknown, primarily as a result of varying definitions and diagnoses of the underlying pathological changes. Despite numerous studies of treatment of the Achilles tendon injuries, the longterm results are not well known. The results after surgical treatment of chronic partial Achilles tendon ruptures in 64 patients with a follow-up of 6 (1.5–11) years were evaluated in a retrospective study. The ruptures were divided into three groups: (I) proximal (more than 3 cm above the calcaneus), (II) distal and (III) combined (proximal and distal). All patients underwent an operation involving the excision of the devitalized tendon tissue and, in groups (II) and (III), also the excision of the deep Achilles bursa and removal of the dorsal corner of the calcaneus. The functional results were satisfactory in 43 (67%) patients and unsatisfactory in 21 (33%). The results were better in patients with proximal ruptures than in patients with either distal or combined ruptures. Males experienced better results than females. Post-operative immobilization in a plaster cast had no significant influence on the final result. Nine (14%) patients with either a distal or a combined rupture were re-operated on and in seven of them the final result was satisfactory. The conclusion of this study is that partial Achilles tendon ruptures are often difficult to treat and only two out of three patients can be expected to obtain satisfactory results after surgical treatment.     

Etiology and pathophysiology of tendon ruptures in sports

Of all spontaneous tendon ruptures, complete Achilles tendon tears are most closely associated with sports activities (1–3). Schönbauer (3) reported that 75% of all ruptures of the Achilles tendon are related to sports. In Plecko & Passl (2) the number was 60%. In our material of 430 cases, the number of sports-related Achilles ruptures was very similar (62%), while only 2% of ruptures of other tendons were sports-related (P<0.001) (1). Also, the majority of Achilles reruptures occurred in sports. The ruptures occurred most often in soccer (34%), track and field (16%) and basketball (14%). The distribution of Achilles ruptures according to different sports varies considerably from country to country, according to the national sport traditions. For example, in northern and middle Europe, soccer, tennis, track and field, indoor ball games, downhill skiing, and gymnastics are the most common; and in North America, football, basketball, baseball, tennis and downhill skiing dominate the statistics (1, 2, 4). In sports, some Achilles ruptures are not spontaneous or degeneration-induced but may occur as a consequence of the remarkably high forces that are involved in the performance (2). Ruptures in the high jump or triple jump are good examples. In such cases, failure in the neuromuscular protective mechanisms due to fatigue or disturbed co-ordination can frequently be found. The spontaneous complete rupture of the supraspinatus tendon of the rotator cuff does not occur very frequently in sports. Those sports that include high-energy throwing movements, such as American and Finnish baseball, American football, rugby and discus and javelin throwing, may, however, produce this injury. Partial tears and inflammations of the rotator cuff complex are much more frequent in throwing sports. The complete rupture of the proximal long head of the biceps brachii tendon is rare among competitive and recreational athletes. In our material, under 2% of these ruptures were associated with sports activities (5). The rupture (avulsion) of the distal tendon of the biceps muscle is rare. In sports, gymnastics, body building and weight lifting have been said to be able to produce this injury (6). In general, complete ruptures of the quadriceps tendon and the patellar tendon occur most often in older individuals. In our study, the mean age of these patients was 65 years (5). However, these injuries do also occur in younger age groups, especially in athletes. In athletes, the rupture most frequently occurs in high-power sports events, such as high jump, basketball and weight lifting, at the age of 15-30 years. A chronic patellar apicitis (jumper's knee) may predispose rupture of the tendon (7). As is the case with the rotator cuff complex, overuse inflammation and partial tears of the quadriceps and patellar tendons are one of the most characteristic athletic injuries. Complete spontaneous ruptures of other tendons in sports are rare, although the literature does provide case studies from almost every tendon the human body possesses (8–18).     

Flip-flops do not alter the neuromuscular function of the gastrocnemius muscle and tendon during walking in children

Introduction/Aim: Flip-flops are a popular choice of footwear for children. However, their inherent design provides minimal support to the foot and ankle and has been suggested to increase the work performed by muscle and tendon structures, potentially predisposing them to injury. Therefore, the aim of this study was to compare the length change behaviour of the medial gastrocnemius (MG) muscle fascicles and muscle tendon unit (MTU) and their mechanical function at the ankle and subtalar joints in children during walking with and without flip-flop. Methods: Eight healthy children walked barefoot and with flip-flops whilst 3D gait analysis and simultaneous B-mode ultrasound images of the MG fascicles during level walking were collected. Joint kinematics, kinetics and MTU lengths were analysed using musculoskeletal modelling and fascicle lengths using a semi-automated tracking algorithm. Results: The muscles and tendons across the ankle absorbed greater amounts of power during barefoot walking compared to flip-flop walking. The muscle activations of the lateral gastrocnemius, soleus and tibialis anterior remained invariant across the conditions as did the activation, and fascicle length change behaviour of the medial gastrocnemius. In the barefoot condition, there was a trend of greater MTU lengthening, to potentially absorb greater amounts of power, although no differences in shortening was observed during late stance. Conclusion: Walking with flip-flops does not increase the mechanical work performed by the MG muscle at the ankle and subtalar joints, suggesting that flip-flops do not increase the stresses and strains of the Achilles tendon and hence its predisposition to strain induced injury. Instead, our results suggest that flip-flops, act as a compliant surface and absorb energy during contact and hence the strain experienced by the Achilles tendon.     

Popliteal artery entrapment syndrome: morphological classification utilizing MR imaging

Objective To retrospectively analyze magnetic resonance (MR) findings in patients with popliteal arterial entrapment syndrome.Materials and methods This study was a retrospective MRI and CT scan review of 12 patients with 23 limbs with popliteal artery entrapment syndrome (PAES) treated over a 10-yr period. All 12 patients (23 limbs) were evaluated with MR and CT scan (11 patients—bilateral sides; one patient—unilateral side). All cases were classified as to various types of anomalous relationships between the popliteal artery and the neighboring muscles. The PAES was classified to gastrocnemius medial head and lateral head anomaly. Gastrocnemius medial head anomaly was classified according to the classification made by Whelan and Rich, from type 1 to type 6 [12, 13]. Gastrocnemius lateral head anomaly was defined as popliteal artery entrapment due to medially inserted gastrocnemius lateral head or aberrant accessory head of gastrocnemius lateral head.Results The gastrocnemius medial head anomaly was found in 14 limbs (14/23). The classic type 1 was found in none, type 2 in five patients (six limbs), type 3 in four patients (five limbs), type 4 in none, type 5 in one patient (one limb) and type 6 in one patient (two limbs). The uncommon type, i.e. lateral head of gastrocnemius anomaly, was found in five patients (eight limbs).Conclusion The gastrocnemius medial head anomaly was the cause of PAES, and PAES was classified by medial head anomaly. However the gastrocnemius lateral head anomaly was also the cause of PAES, and most cases of gastrocnemius lateral head anomaliy showed aberrant accessory slip which entrapped the popliteal artery and vein.