Tennis leg/calf strain

What is a calf strain or tennis leg?

A calf strain, sometimes called a tennis leg, is an injury to the back of the lower leg commonly encountered in sports. The anatomy here is complex; a few muscles converge to attach to the Achilles tendon, and injuries can happen to any of these structures. Ultrasound is an excellent tool for establishing the site, type and degree of injury and guiding further management.

Relevant calf anatomy

Three muscles run at the calf, the two main calf muscles are the medial (inner) and lateral (outer) gastrocnemius muscles. The third and largest muscle, the soleus, is more flat and deeper in location. The three muscles form the Achilles tendon that runs at the back of the leg and attaches to the back of the heel bone (calcaneum).

The medial and lateral gastrocnemius muscles provide the necessary explosive power for jumping and sprinting. On the other hand, the soleus muscle is responsible for controlling posture and is more active during walking.

A calf muscle strain or tennis leg is one of our practice's most common lower limb injuries. Injuries here are most seen at the inner aspect of the leg, at the junction between the medial gastrocnemius and the Achilles tendon. Injuries are also common between the soleus and medial gastrocnemius muscle. Ultrasound assessment is very useful in determining the site, extent, and type of injury.

How does a calf strain or tennis leg happen?

A tennis leg is mainly post-traumatic, most seen at the junction between the medial gastrocnemius and the deeper soleus muscle. This injury here can be partial or complete, involving the muscle or connective tissue between the muscles (called aponeurosis). Less commonly, the injury involves the outer lateral gastrocnemius muscle. The causes of calf strain include:

1: A calf strain or tennis leg is most seen after a sudden explosive calf movement that involves straightening the knee at the beginning of the run or jump. This movement exerts a very high force upon the calf muscles, increasing the risk of injury.

2: In addition to sports persons, calf injury or tennis leg has a high incidence in people who start to be involved in sports (such as football and running) with poor previous conditioning or training, particularly in males over 40.

3: Rarely a calf strain can be sustained after a minor injury during walking or stretching the calf.

How to tell if I have a tennis leg?

The main symptom of a tennis leg is focal calf pain that starts suddenly while performing a physical activity like running or playing football. The pain is sharp and usually causes you to stop your activity. You may hear a pop at the time of injury and notice swelling and tenderness to the touch.

What are the symptoms of a tennis leg/calf strain?

1: Tennis leg manifests as an abrupt and excruciating calf pain that occurs suddenly during physical activity, like running or playing football.

2: The intensity of the pain is usually severe, and it can cause limping and compels you to stop the activity immediately.

3: Some may report a popping sensation when the injury occurs, accompanied by swelling and tenderness upon touch.

4: If the injury is of high grade, then you may notice a change in the shape of the calf muscle compared to the unaffected side.

What conditions can mimic a tennis leg?

There are a few conditions that can present, like a tennis leg. These include:

Achilles tendinopathy/tear: Achilles tendon problems are usually felt lower down in the leg, at the site of the Achilles tendon. In contrast, calf strains/tennis leg causes pain higher up in the calf. Achilles tendinopathy pain usually builds up gradually unless there is an acute Achilles tendon tear. Tennis leg pain starts suddenly during physical activity. A musculoskeletal ultrasound scan accurately differentiates tennis leg from Achilles tendinopathy/tear.
Baker’s cyst rupture.
Deep vein thrombosis (DVT). This is a serious condition and happens if there is a clot within the deep veins in the leg. It can present with sudden onset calf swelling, pain, and redness. Still, usually, there is no history of sudden onset pain while doing physical activity, which is typical for a tennis leg. A Doppler ultrasound examination can rule this out.

How to diagnose a tennis leg/calf strain?

If you sustain a painful calf injury, you need to be assessed by a musculoskeletal specialist (like a physiotherapist or a foot and ankle specialist). You will be referred for further imaging to identify the site, extent, and type of injury. A dedicated musculoskeletal ultrasound scan is excellent for the assessment.

How can an ultrasound assess a tennis leg?

Ultrasound is very accurate and will provide the following information about the injury:

1: The site of injury. Injury can happen within the muscle itself (intramuscular), where the muscle meets the tendon (myotendinous) or to the connective tissues between the muscles (fascial or aponeurotic). Management differs depending on the type of injury; therefore, the information obtained from an ultrasound scan is crucial.

2: The size of the injury.

3: The extent of injury- partial or complete disruption.

4: Blood products (haematoma) at the injury site.

5: The integrity of the Achilles tendon.

6: A Doppler ultrasound scan will rule out a clot within the leg's deep veins (DVT).

7: Following up the recovery and healing at the site of injury.

All the information above can be obtained from an ultrasound examination when performed by an experienced practitioner.

What is the treatment for tennis leg/calf strain?

In most cases, the management is conservative, consisting of a short rest period and gradual build-up of activity under the supervision of an experienced physiotherapist. The rest period aims to prevent further injury and allow for healing. The dedicated physiotherapy program aims to improve muscle strength, balance, and stability. An ultrasound is needed initially to assess the injury and guide the management. In addition to the above measures, pain management using painkiller tablets, ice and elevation can also be useful.

If the injury is significant and causes significant disruption to the calf muscles or tendons, surgical treatment might be indicated, but this is rare as most cases of tennis leg are managed conservatively.