Tennis Leg: Why the Calf Feels Like It Was Kicked, and How It Is Treated

The calf feels like it was kicked.

In the clinic, many patients with a serious calf tear describe it exactly that way when they walk in. Such presentations can point to a calf muscle tear, an Achilles tendon rupture, and other injuries. The calf is made up of three main muscles: the more superficial medial and lateral heads of the gastrocnemius, and the deeper soleus, which sits in the middle.

The condition was first described in 1883 in a tennis player, and at the time it was attributed to a rupture of the gastrocnemius tendon. The gastrocnemius tendon has been implicated in this injury for many years. Medial gastrocnemius injury, also known as tennis leg, refers to varying degrees of injury at the musculotendinous region of the medial gastrocnemius, caused by the ankle suddenly dorsiflexing under eccentric load (an athlete may also sustain it when an external force causes sudden stretch or dorsiflexion during active plantarflexion). It happens during sport, but the mechanisms involved may also be work-related.

Lawn tennis as a sport began in 1874, its first set of rules was written in 1875, and the first Wimbledon Championships were held as early as 1877. Tennis quickly became very popular, and Dr Wharton P. Hood, who took part in the sport himself, wrote an article titled “On lawn-tennis leg” based on his own 14 years of clinical experience. The emergence of a new sport led to new injuries and eponymous names, and the term may have originated from this article.

Muscle strains most often occur in muscles that cross two joints, such as the hamstrings, rectus femoris, and gastrocnemius. So when people talk about a calf strain, they usually mean a gastrocnemius strain. Various sports such as rugby, soccer, tennis, track and field, and dance are affected by calf muscle strains; in soccer, 92% of injuries are muscle injuries, and 13% of those are calf injuries.

Risk Factors

• Male
• Aged 40 to 60
• Taking part in sports that require rapid acceleration (such as tennis, squash, uphill running, and jumping track events), and it may even occur during relatively low-intensity activities such as climbing stairs
• Inadequately warmed-up muscles are more prone to injury
• During prolonged activity, muscle fatigue and poor coordination also increase the risk of injury

History

Patients usually hear a clear pop or feel a tearing sensation on the inner calf at the time of injury, and may describe it as feeling like being struck by a stick. A strain at the proximal medial musculotendinous junction is the most common type of gastrocnemius injury. The gastrocnemius is predominantly Type II muscle, giving it better explosive power, and the medial muscle is more prone to injury than the lateral one.

Unlike the gastrocnemius, the soleus is considered to be at lower risk of injury. It crosses only the ankle joint and is composed mainly of Type I slow-twitch fibers. Compared with gastrocnemius injuries, soleus strains tend to be less dramatic in their clinical presentation and relatively subacute, and this condition often occurs in middle-aged patients who are less fit and/or highly physically active.

Physical Examination

• Asymmetric calf swelling, with a measurable increase in calf circumference, and swelling that may extend to the ankle
• Bruising on the inner calf, which may also extend to the back of the ankle
• A visible or palpable defect at the medial gastrocnemius
• Pain on palpation of the calf, especially at the medial musculotendinous junction
• Peripheral pulses should be normal
• Passive ankle dorsiflexion (pulling the foot upward) provokes pain, and active resisted plantarflexion testing also provokes pain
• The Thompson test to rule out an Achilles tendon rupture

Differential Diagnosis

• Ruptured Baker’s cyst
• Deep vein thrombosis (DVT)
• Plantaris tendon rupture
• Achilles tendon rupture
• Acute compartment syndrome following a medial gastrocnemius rupture
• Chronic exertional compartment syndrome (posterior)
• Posterior tibial tendon rupture or tendinitis
• Popliteal artery entrapment syndrome

Injury Grading

Muscle injuries were traditionally divided into three grades. In recent years a number of studies have begun to discuss classifying them by region and histology, which better predicts prognosis. See the further reading for details.

Grade I muscle strain

• Symptoms:

  • There may be a feeling of tightness
  • May be able to continue activity, with no pain or only mild discomfort
  • Increased tightness and/or pain after activity
  • Pain on a single-leg calf raise or when jumping

• Average return-to-sport time:

• 14 - 21 days

Grade II partial muscle tear

• Symptoms:

  • Sharp calf pain during activity
  • There may be muscle swelling, with mild to moderate bruising
  • Pain on active plantarflexion, and loss of dorsiflexion ability

• Average return-to-sport time:

• 21 - 42 days

Grade III complete muscle tear

• Symptoms:

  • Severe and immediate calf pain, usually at the musculotendinous junction
  • Unable to continue the activity
  • Fairly obvious bruising and swelling within a few hours of injury
  • Unable to contract the calf muscle, with a possible visible muscle depression

• Average return-to-sport time:

• More than 2 to 3 months after treatment

Anatomy

This part of the anatomy is closely related to grading and diagnosis. Injuries affecting the medial gastrocnemius vary greatly in presentation, and although the injury mechanism is the same, the prognosis is highly variable — all of which can be observed on ultrasound. A 2007 study described the main structures involved, including the following anatomy:

• MGA (medial gastrocnemius aponeurosis)
• SA (soleus aponeurosis)
• FGA (free gastrocnemius aponeurosis)
• AT (Achilles tendon)

Diagnostic Tools

• Can be diagnosed from clinical findings without advanced imaging, though severity is harder to judge

• X-ray: can be used to rule out an avulsion fracture or calcific tendinopathy

• MRI: the most sensitive and specific imaging technique, showing damaged soft tissue and surrounding structures, though it usually takes longer and is costly when self-paid

• Ultrasound (US): helps rule out DVT or an Achilles tendon rupture, and can also be used to monitor the extent of the calf injury and its healing over time; it is a relatively convenient, easy-to-track, and lower-cost examination

• Type 1: myoaponeurotic injury — injury at the myoaponeurotic junction

• Medial gastrocnemius aponeurosis: intact

• Fibroadipose septum appearance: retracted

• Muscle fiber state: retracted

• Hematoma infiltration: between the septum and the aponeurosis

• Hematoma: none

• Synchronous motion with ankle plantarflexion and dorsiflexion: good

• Type 2: gastrocnemius aponeurotic injury — affects the aponeurosis, with discontinuity or hematoma visible

• Medial gastrocnemius aponeurosis: ruptured (2a or 2b depending on extent)

• Fibroadipose septum appearance: retracted

• Muscle fiber state: retracted

• Hematoma: between the septum and the fascia

• Hematoma: intermuscular space (+/-)

• Synchronous motion: depends on the width of the aponeurotic rupture

• Type 2a: gastrocnemius aponeurotic injury (transverse scan under 50% GA)

• Type 2b: gastrocnemius aponeurotic injury (transverse scan over 50% GA)

• Type 3: free gastrocnemius aponeurotic injury — affects the free aponeurosis of the muscle, located distally

• Medial gastrocnemius aponeurosis: free aponeurosis affected

• Fibroadipose septum appearance: fairly normal

• Muscle fiber appearance: fairly normal

• Hematoma infiltration: none or very slight

• Hematoma: none

• Synchronous motion: usually preserved

• Type 4: mixed injury — a combination of Type 2b and Type 3, requiring the longest recovery time

Treatment

• General measures
  • Reduce swelling: elevate the injured limb, use a compression dressing or sleeve, and ice for 10 to 20 minutes 3 to 4 times a day until the swelling eases
  • Short-term reduced weight-bearing: one or two crutches may be needed for assistance, and if pain improves, starting partial weight-bearing early is recommended
  • Ankle/foot brace: keep the ankle in a tolerable flexed position; using it at night in the early phase can help with treatment
• Medication: anti-inflammatory painkillers (NSAIDs), though cautious use is advised to avoid bleeding, and they can be avoided if there is no pain

Additional Treatments

• Aspirating drainable bruising or blood clots may be suggested to reduce swelling and pain
• Depending on the situation, prolotherapy or PRP injection may be considered to reduce pain and support muscle recovery
• Once tolerable, partial weight-bearing walking so the sole makes maximal contact with the ground
• Active resisted ankle dorsiflexion exercises, up to the point where the athlete is pain-free
• Progressive stationary cycling, leg press, and heel raise exercises
• Proprioception and balance training

Prognosis

• The outlook is good, and most patients can return to sport within a few weeks
• Low adherence or slow recovery may leave athletes unable to return to sport within 3 to 4 months
• Early and active rehabilitation allows most patients to recover fully within a short time
• Watch for the complication of calf vein thrombosis, which occurs in about 10% of cases

References

• Radiol Case Rep. 2016 Nov 29;12(1):120–123.
• Injury. 2021 Nov;52(11):3355-3361.
• Radiology. 2002 Jul;224(1):112-9
• Scand J Med Sci Sports. 2020 Dec;30(12):2456-2465.

Further reading

Understanding muscle tears in depth: from the traditional three grades to recent five-grade classification