Calf Strain

'Original Editors ' Kim De Maeght, Bettina Vansintjan, Maite Van Roozendael and Lenka Pé

Search Strategy

We used the VUB library to access databases such as Pubmed, Web of science and Google scholar to find articles related to calf strains. As search keywords we used terms like ‘calf strain’, ‘tennis leg’, ‘gastrocnemius rupture’, ‘soleus tear’ and other synonyms.

Definition/Description

Calf strain is a common muscle injury. It is a tear of the muscle fibres of the muscles at the back of the lower leg. Strains are the result of excessive stretching or stretching while the muscle is being activated. Tendons are an important part of the muscle which means strains may also involve causing damage to tendons. Strains may be referred to as a “pulled muscle”. 

Clinically Relevant Anatomy

The “calf muscle”, on the back of the lower leg, is composed of three muscles: the gastrocnemius, the soleus and the plantaris, which together constitute the triceps surae. These muscles come together as the achilles tendon and insert all three muscles on the calcaneus.

The gastrocnemius is part of the posterior compartment of the leg and comprises of two parts, the medial head and the lateral head. The medial head arises from the medial condyl of the femur and the lateral head originates from the lateral condyl of the femur.  The gastrocnemius provides primarily plantar flexion and flexion at knee joint.  The gastrocnemius is innervated by the tibial nerve. The tibial nerve (branche of the sciatic nerve) passes through the popliteal fossa where the nerve gives off a branche to the gastrocnemius. 

The soleus is located beneath the gastrocnemius muscle in the superficial posterior compartment of the lower leg. The muscle originates from the upper 1/3 on the back of the tibia, from the back of the head of the fibula and the upper part of the posterior surface of the fibular shaft and the fibrous arch that lies between the tibia and the fibula.  The main function is plantar flexion of the ankle and stabilizing the tibia on the calcaneus limiting forward sway.  The soleus is innervated by the tibial nerve, who passes behind the muscle through the fibrous arch of the soleus. 

The plantaris is located in the posterosuperficial compartment of the calf. The muscle originates from the lateral supracondylar line of the femur (superior and medial to the lateral head of gastrocnemius) and from the oblique popliteal ligament. It is a long, small muscle with a long thin tendon. The plantaris is also innervated by the tibial nerve. In terms of function, the plantaris acts with the gastrocnemius but is trifling as either a flexor of the knee or plantarflexor of the ankle. 

Epidemiology/Etiology

Muscle strains most commonly occur in bi-articular muscles such as the hamstrings, rectus femoris and gastrocnemius. During sporting activities such as sprinting, these long, bi-articular muscles have to cope with high internal forces and rapid changes in muscle length and mode of contraction. However, muscle strains have also been reported to occur during slow-lengthening muscle actions such as those performed by ballet dancers, but also during common daily activities.  The gastrocnemius is considered at high risk for strains because it crosses two joints (the knee and ankle) and has a high density of type two fast twitch muscle fibers.  A tear of the medial head of the gastrocnemius muscle is due to an eccentric force being applied to the gastrocnemius muscle when the knee is extended and the ankle is dorsiflexed. The gastrocnemius muscle attempts to contract in the already lengthened state leading to tear of the muscle.  The soleus muscle on the other hand is injured while the knee is in flexion. Strains of the proximal medial musculotendinous junction are the most common type of soleus muscle injuries. Unlike the gastrocnemius the soleus is considered low risk for injury. It crosses only the ankle and is largely comprised of type one slow twitch muscle fibers. Soleus strains also tend to be less dramatic in clinical presentation and more subacute when compared to injuries of the gastrocnemius. 

This condition occurs frequently in the middle-aged, poorly conditioned, physically active patient. 

Characteristics/Clinical Presentation

It is important to differentiating strains in these muscles to form the correct prognosis, an appropriate treatment and prevention of recurrent injury. 

Gastrocnemius strains
Calf strains are most commonly found in the medial head of the gastrocnemius.  In an effort to contract, the forces of the eccentric movement on the already lengthened gastrocnemius muscle lead to injury at the myotendinous junction. The physical examination immediately after the injury reveals a palpable defect in the medial belly of the gastrocnemius just above the musculotendinous junction.  A sudden pain is felt in the calf, and the patients often report an audible or palpable "pop" in the medial aspect of the posterior calf, or they have a feeling as though someone has kicked the back of their leg. Substantial pain and swelling usually develop during the following 24 hours. 
Gastrocnemius is vulnerable to injury because it is a “fast-action” muscle with type IIb muscle fibers and because of its position spanning across two joints: the knee and ankle.  Strains in the gastrocnemius may be referred to as a “tennis leg”. 

Soleus strains
The soleus is considered low risk for injury in contrast to the gastrocnemius. It crosses only the ankle and is largely composed of type one slow twitch muscle fibers. 
Soleus strains tend to be less dramatic in clinical presentation and more subacute when compared to injuries of the gastrocnemius. Injury of the soleus muscle may be underreported due to misdiagnosis as thrombophlebitis or lumping of soleus strains with strains of the gastrocnemius.  Soleus strain causes pain when activating the calf muscle or when applying pressure on the Achilles tendon approximately 4 cm above the anchor point on the heel bone or higher up in the calf muscle. Stretching the tendon and walking on tip-toe will also aggravate pain. 

Plantaris strains
The plantaris is considered largely vestigial and rarely involved in calf strains, although it crosses the knee and the ankle joint too.  Rupture of the plantaris muscle may occur at the myotendinous junction with or without an associated hematoma or partial tear of the medial head of the gastrocnemius muscle or soleus.  Injury to plantaris muscle can present with similar clinical features as those of the gastrocnemius and soleus muscle. 

Differential Diagnosis

Pain in the lower leg can indicate shin splints, Achilles tendinitis, plantar fasciitis, muscles strains and joint sprains which can be caused by lack of extensibility of the plantar-flexors and decreases in ankle dorsiflexion.  The different degrees of muscle strains are discussed above. People commonly get a strain while practicing sports. Other injuries at the lower leg related to sports with the same symptoms and treatment as a calf strain are discussed below. 

Runners often complain about lower leg pain along the posteromedial border of the tibia.  This is called “shin splints” or medial tibial stress syndrome (MTSS).  They describe the pain as tenderness located a few centimetres proximal to the medial malleolus, spreading proximally about 4 to 10 centimetres. The cause of MTSS is often an inappropriate warming up or overuse of the painful area. http://www.physio-pedia.com/Shin-splints

Pain located anterior or anteromedial of the tibia can indicate a tibial stress fracture, typical for runners and people playing footbal.   It occurs after changes in the intensity, duration and frequency of a workout but other personal and environmental factors can contribute to this injury. Radiographs initially are negative but later, we can visualise fracture lines around the involved area like “the dreaded back line”. Sometimes an operation is necessary but it can be treated the same way as a calf strain: rest, stretching and strengthening of lower extremity musculature, NSAIDs and appropriate footwear.
http://www.physio-pedia.com/Leg_and_Foot_Stress_Fractures

A great amount of repeatable exercises can cause chronic exertional compartment syndrome (CECS).  CECS begins with mild pain during a part of the exercise routine and disappears when exercise is over. In a later stage, pain presents earlier, more painful and lasts longer so the athlete must stop his activity. People complain about cramps, paraesthesia, numbness and weakness in the lower leg. CECS is caused by the increased intramuscular blood flow during exercise so compartmental pressure arises. By this capillaries become compressed and ischemia develops. 
http://www.physio-pedia.com/Compartment_Syndrome_of_the_Lower_Leg

Leg pain around the same area as a gastrocnemius strain can be caused by Popliteal Artery Entrapment Syndrome (PAES), this is an abnormal course of the popliteal artery. Medial and cranial migration of the medial head of the gastrocnemius can catch the popliteal artery and swipe it medially. This is called anatomical PAES, an abnormal relationship between the popliteal artery and the surrounding myofascial structures. Functional PAES is caused by muscle contraction, often active plantarflexion of the ankle that compresses the artery between the muscle and underlying bone. 
http://www.physio-pedia.com/Posterior_Knee_Pain

Another injury at the lower extremity is an inflammation of the Achilles tendon, called Achilles tendinitis.  The etiology is often a sudden change in duration, intensity or frequency of training and imbalances of the muscles of the lower extremities or torso, but also inappropriate footwear is a risk factor. Swelling of the tendon and posterior lower leg and ankle pain are the main characteristics. Achilles tendinitis is treated about the same way as a Calf strain.
A posterior tibialis tendinitis can also cause posteromedial lower leg pain.  This muscle and tendon are important to stabilize the midfoot. Chronic microtrauma related to repetitive overload of running and intrinsic factors like weak calf muscles lead to this injury. Examination concludes tenderness posterior or inferior and proximal or distal to the medial malleolus. 
http://www.physio-pedia.com/Achilles_Tendinopathy

Lack of extensibility of the gastrocnemius and soleus muscle, weakness of the plantar flexors and training errors can cause plantar fasciitis.  Pain is located in the heel distal to the calcaneus and later maybe to the midfoot. Plantar fasciitis can be treated with the application of ice, phonophoresis, cross-friction massage and stretching of the calf muscles and plantar fascial tissues. 
http://www.physio-pedia.com/Plantarfasciitis

Diagnostic Procedures

Sometimes a precise clinical examination is enough to formulate a hypothesis of possible diagnoses, but it is often difficult to reach a correct diagnosis because the clinical signs of tennis leg can easily be confused with other pathological conditions. For this reason diagnostic imaging is necessary. Ultrasonography (US) is considered being the gold standard in the diagnosis of tennis leg because it is inexpensive, non-invasive and easy to perform. It can also be used to evaluate the degree and extent of the muscular lesion and to exclude other pathologies such as ruptured Baker's cyst and deep vein thrombosis. Deep vein thrombosis however needs particular attention as it requires a different therapeutic management. 
Ruptures are usually associated with the presence of fluid collection between the soleus muscle and the medial head of the gastrocnemius. This can occur with or without hemorrhage. The measurement of fluid collection gives us information about the extent of the lesion. The degree of the lesion (partial or complete rupture) can be defined by the distance between the two muscles. Axial US scans are the most useful for differentiating between partial and complete rupture, as it is possible to depict the whole muscle belly in one single image. 

A calf muscle tear is a most common injury in sports such as running, volleyball, tennis, etc. These sports require quick acceleration of changes in direction and are more dangerous for a calf strain injury. Muscle strains are graded as mild, moderate and severe. The more severe the strain, the longer the time to recover. Typical symptoms are stiffness, discoloration and bruising around the strained muscle. 

Grade I:
A first degree (mild) injury is the most common and usually the most minor. There will be a sharp pain at the time of injury or pain with activity. It can also be a contracture, which comes from a shortening of the muscle (e.g. immobilization) and cause a sharp pain at the moment, but can be prevented by stretching. You will usually be able to continue activity. There is no or minimal loss of strength and range-of-motion. It is an injury with a muscle fiber disruption of less than 10 percent. With a first degree injury you can expect to play sports within 1 to 3 weeks. 

Grade II:
A second degree (moderate) injury is a partial muscle tear. You will be unable to continue activity. Clear loss of strength and range of motion can occur.  Also marked with pain and swelling. Bruising may occur when the blood vessels are damaged around the injury. With a second degree injury there will be a muscle fiber disruption between 10 and 50 percent. It requires 3 to 6 weeks of recovery before you can return to full activity. 

Grade III:
A third degree (severe) injury results in a complete tearing of the muscle-tendon unit and is often combined with a hematoma which makes it impossible to keep exercising.  Pain, swelling, tenderness and bruising are usually present. In this case there will be a muscle fiber disruption between 50 and 100 percent. When you have a third degree injury it can take more weeks or even months before you are fully recovered and go back to full activity again. 

Outcome Measures

1.  LEFS: Lower Extremity Functional Scale
   http://www.physio-pedia.com/Lower_Extremity_Functional_Scale_(LEFS)
2. VAS: Visual Analogue Scale
   http://www.physio-pedia.com/Visual_Analogue_Scale
3. NPRS: Numeric Pain Rating Scale
   http://www.physio-pedia.com/Numeric_Pain_Rating_Scale
4. Muscle Strength testing: grade 0 is the lowest grade where the patient isn’t capable of doing any contraction of the muscle. Grade 5 is the highest grade where the patient is able to move his leg against a maximum resistance given by the therapist.
   http://www.physio-pedia.com/Muscle_Strength

Examination

The physical exam is of great importance as it allows us to isolate the site and severity of injury. A combination of palpation, strength testing, and stretching is necessary to help distinguish strains of the soleus and gastrocnemius muscle.

Palpation of the calf should occur along the entire length of the muscles and the aponeuroses. This is required to identify swelling, thickening, tenderness, defects and masses if present.
Strains of the gastrocnemius muscle usually present with tenderness in the medial belly or musculotendinous junction, while soleus strains often occur with lateral pain.

There are multiple techniques that exist to assess calf strains.
Considering that the origin of the gastrocnemius is situated above the knee (epicondylus lateralis and medialis femoris) and the origin of the soleus finds itself below the knee (caput fibulae), it allows the therapist to isolate the activation of the muscles by varying the degree of knee flexion. The soleus becomes the main source of force in plantar flexion, with the knee in maximal flexion. On the contrary, when the knee is in full extension, it is the gastrocnemius who provides more strength. This relationship allows for more accurate strength testing of the individual calf muscles and enables the examiner to describe which muscle has been injured.

Another similar method is used to test flexibility and pain during stretching and passive ankle movements. This technique allows us to determine the site of injury by isolating the gastrocnemius and soleus muscle. During the test, the knee is placed in maximal extension and thereafter in flexion while the ankle is passively dorsiflexed. This causes isolated stretch of the gastrocnemius and the soleus otherwise.

Additional testing that can be used during evaluation of calf strain includes the Thompson test for complete disruption of the Achilles tendon. It should also be noted that simultaneous tears of the gastrocnemius and soleus are possible, which can complicate the clinical picture.

If the diagnosis is still in doubt after these tests, the use of imaging can be helpful. The two choices of imaging are MRI and muskuloskeletal ultrasound (MSK US). Both can be used to confirm strain, localize the injured muscle and determine extent of injury.   

Medical Management

Calf strains rarely require surgery, but it is possible in extreme cases. Surgery can happen to the medial head of the gastrocnemius and also when the calf muscle is completely ruptured. However, rehabilitation will be recommended and also methods like RICE (see physical therapy management below).  (Level Of Evidence 5) An injection of local anesthetic and cortisone in and around the area, followed by a right stretching and stretch training treatment, will often take away some of the symptoms. When your muscle is torn there can occur a hematoma and it’s important to get this removed as quickly as possible, otherwise there may be complications such as myositis ossificans. This can be prevented with rehabilitation. When you’re unsure if your muscle is torn, it is best to visit a doctor who will refer you to a specialist to take an RX, MRI or ultrasonography for further investigation.  (Level Of Evidence 1b)

Prevention:

To prevent a calf muscle tear you can stretch these muscles every night.  (Level Of Evidence 1a) This will ensure that the gastrocnemius and soleus will not shorten and the joint mobility will increase.
When the muscles are extended, there can be a greater force delivered and the muscles are less tense which improves the blood flow.  (Level Of Evidence 2b)  (Level Of Evidence 1a)
Muscle stretching is easy to perform and has a low risk of side effects. It’s recommended to stretch one to three times a day for optimal results.  (Level Of Evidence 1a) (For more information about how to stretch, see physical therapy management).

Physical Therapy Management

The task of the physiotherapist contains:

1. Settle down the pain
2. Restore flexibility
3. Restore strength
   
   

The principal treatment of a calf strain consists of rest and allowing time to heal, but in severe cases, people undergo surgery. In normal cases passive stretching, exercises for the antagonists and later the agonist and quadriceps exercises satisfy to heal the injury and reduce the pain.  (Level Of  Evidence 2a) At a later stage, patients can also be treated with massage of the calf muscles, ultrasound and electrical stimulation.  (Level of evidence 1a)

The aim of acute treatment is to limit bleeding and pain and to prevent complications. For the acute treatment we use the “RICE” principle that includes rest, ice, compression and elevation.  (Level of evidence 1b) The patient himself can apply ice in a towel to the painful area to relieve the pain with an endurance of 20 minutes. Otherwise a physiotherapist can use cryotherapy to decrease inflammation, pain and cell metabolism. Tape or a compressive wrap can be applied and the leg needs to be elevated.  (Level of evidence 2a) If major bleeding had occurred, it is necessary to be careful with the use of NSAIDs. NSAID’s have an antiplatelet effect which can increase bleeding as well as the early application of moist heat and massage does.  (Level of Evidence 1b)

After this, the patient can start with passive stretching exercises. Stretching promotes the range of motion of the plantar flexors, which is limited by shortness and contractures.  (Level of evidence 2b) The patient sits with the foot and lower leg straight out in front. It is important that the knee is in full extension so the gastrocnemius can be stretched.  (Level of evidence 1b) A calico bandage 8 to 10 feet long is twisted around the foot and held by the patient. The patient pulls the bandage towards him so a dorsiflexion of the ankle is performed. The stretching of the calf muscle is held in a phase of discomfort but without pain. The stretch is held for 10 seconds alternated with 10 seconds of relaxation. This cycle is repeated for 10 minutes. After this stretching protocol, 5 minutes of ultrasound therapy is applied at a dose of 0.5 to 2 watts per CM2 to change the viscoelasticity of the collages so any soreness caused by the stretching is relieved. Applying superficial heat simultaneously with a low load static stretch improves the flexibility of muscles.  (Level of evidence 2a)

The next step is 10 minutes of isotonic exercises for the antagonist (M. Tibialis Anterior, Mm. Peronei) and 10 minutes of exercises for the injured muscle. This whole process of stretching and exercises is carried out two to three times in the first 3 days after injury. It is important that the patient performs this process also at home.  (Level of evidence 2a) Lack of extensibility of the plantar flexors can cause decreases in ankle dorsiflexion and disturbs the gait. That is why patients should wear shoes with a low heel to perform correctly a heel-toe gait.  (Level of evidence 2b)

After forty-eight hours, ice is not an effective analgesic so short-wave diathermy is given for 20 minutes. A feeling of warmth is produced but no discomfort. A strain with abnormal swelling and bruising is treated with interferential therapy which produces a low frequency electric current to the injury. The aim of this method is to relieve the pain and to stimulate the muscle fibres.  (Level of evidence 2a)

Quadriceps exercises of 10 minutes are essential to protect the knee joint when returning to sports. When the muscle can be fully extended, we can switch from the passive stretch to a standing stretch.  (Level of evidence 2a) The patient stands with the foot of his normal leg 1 to 2 feet in front of the other foot and parallel to it. The heel of the injured leg is kept on the floor and the knee is straightened the whole time. The knee of the normal leg is flexed as far as the knee is forward over the forefoot. By flexing the knee, the soleus is elongated and the gastrocnemius is slacken. This stretch is continued for 10 sec. When the patient doesn’t feel the stretch, the front foot should be moved more forward until a phase of discomfort is felt. 

After 10 days the patient can perform isometric, isotonic and dynamic exercises to improve tensile strength.  (Level of evidence 1b)

Another treatment consists of vibration therapy (VT). Vibration therapy is applied specific on the area of injury and treats muscle strains and other myo-tendinous injuries that involve trigger points.  (Level of evidence 1a) Broadbent et al. suppose that VT stimulates the sensory receptors, but it causes also a decrease of inflammatory cells and receptors like IL6 and histamine.  The aim of this therapy is an increase in muscle strength, flexibility and extensibility. A SVT device (the V-Actor device) is placed on the injured area followed by a radial pressure wave (the D-Actor device) that gives impulses. The treatment duration is recommended for 4 minutes. After a VT treatment, jumping and running are forbidden for at least 3 to 6 weeks and NSAIDS are discouraged but other treatment routines can be continued. An advantage compared with other therapies like sound wave therapy and ESWT treatments, is that VT can be applied more frequently. 

Strains may cause long lasting pain, despite an adequate early treatment. The average time of treatment is nine days. The treatment is successfully accomplished when there is no more pain, when the calf muscle can be fully extended, when there is as much power in the lower leg and thigh as on the non-injured side, when ranges of knee and ankle are normal and when excessive tenderness has disappeared.  (Level of evidence 2a) Only when full extensibility and strength is achieved, the patient can return to his pre-injury activity.

Key Research

Millar, A. P., “Strains of the posterior calf musculature ("tennis leg")*.”The American Journal of Sports Medicine, vol. 7, no. 3, 1979, pp. 172-174. [Level of evidence 2a]

Ellen, Mark I., Jeffrey L. Young, and James L. Sarni. "3. Knee and lower extremity injuries." Archives of physical medicine and rehabilitation 80.5 (1999): S59-S67.

Bryan Dixon J. Gastrocnemius vs. soleus strain: how to differentiate and deal with calf muscle injuries. Current Reviews in Musculoskeletal Medicine. 2009;2(2):74-77. doi:10.1007/s12178-009-9045-8. [Level of evidence 1b]

Resources

All information used for this physiopedia subject is found on Pubmed, Physiopedia and Web Of Science. We also checked www.sportsinjuryclinic.net and www.moveforwardpt.com for global background information about calf strain.

Clinical Bottom Line

Pain in the calf muscle is often due to a strain however there are other conditions which could cause similar symptoms, including deep vein thrombosis and contusions. Treatment of muscle injuries usually has good outcome. Calf strains vary in healing time depending on how severe the strain is. In normal cases stretching and exercises satisfy to heal the injury and reduce the pain. Massage of the calf muscles, ultrasound and electrical stimulation can also be used in the treatment.

Recent Related Research (from Pubmed)

The only recent relevant information related to calf strains found on Pubmed includes information about ultrasound elastography. The articles date from 2015 till 2016 so this reflects the interest in new research associated with ultrasound.