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Ankle equinus is a prevalent condition affecting pediatric and adult patients with foot and ankle pathology. Ankle equinus is a general term used to describe the position of the ankle when it is plantar flexed or when passive or active ankle dorsiflexion is limited by 5° to 10°. The condition can stem from multiple etiologies, including osseous limitations, neuromuscular disorders, or contractures of the gastrocnemius complex or surrounding soft tissues. Ankle equinus can significantly impact gait and mobility, presenting in both stance and swing phases or as part of a pathologic deformity due to an overtightened gastrocnemius-soleus complex. Managing ankle equinus requires a comprehensive approach, beginning with a thorough evaluation to identify the underlying cause. Diagnosis typically involves a clinical examination and, when necessary, imaging such as x-rays or MRI, especially if conservative treatments fail or if osseous or neurological issues are suspected. Treatment options range from conservative methods, such as stretching and orthotics, to surgical interventions to restore normal ankle function. This activity reviews the etiologies, diagnosis, and current management options for varying presentations of ankle equinus. This activity also highlights the critical roles of an interprofessional healthcare team in accurately diagnosing ankle equinus and tailoring individualized treatment plans. This activity equips clinicians with a deep understanding of biomechanical implications, helps identify critical clinical signs, and explores both conservative and surgical treatment options. In addition, this activity allows clinicians to address ankle equinus challenges in clinical practice, ultimately improving patient mobility and quality of life. Objectives: Identify the clinical signs and risk factors associated with ankle equinus to facilitate early recognition and intervention. Implement evidence-based diagnostic tools, including physical examination techniques and imaging studies, to accurately assess ankle equinus. Apply appropriate conservative treatment options, such as stretching exercises, orthotics, and physical therapy, to manage mild-to-moderate cases of ankle equinus. Collaborate with interdisciplinary healthcare teams to develop comprehensive treatment plans for ankle equinus, monitor progress, adjust treatment as needed, and prevent recurrence.

Apply appropriate conservative treatment options, such as stretching exercises, orthotics, and physical therapy, to manage mild-to-moderate cases of ankle equinus. Collaborate with interdisciplinary healthcare teams to develop comprehensive treatment plans for ankle equinus, monitor progress, adjust treatment as needed, and prevent recurrence. Access free multiple choice questions on this topic.

Ankle equinus is a prevalent finding in patients with foot and ankle pathology, and it is documented in 96.5% of patients presenting to a podiatric clinic with a new foot or ankle complaint.[1] Ankle equinus is characterized by decreased dorsiflexion of the ankle or tibiotalar joint, although no specific degree of dorsiflexion loss is defined in the literature for diagnosis.[2] The term "ankle equinus" can be described as the ankle's position in the sagittal plane, a gait pattern, or a a pathologic deformity, when combined with other terms. When used to describe a gait pattern, ankle equinus refers to the ankle plantar flexion in both the stance and swing gait phases.[3][4] In addition, when describing a pathologic deformity, ankle equinus often results from overtightening of the gastrocnemius-soleus complex, leading to an overpull of the Achilles tendon at its insertion on the calcaneal tuberosity.

Ankle equinus can result from osseous limitations, neuromuscular disorders, or contractures of the gastrocnemius complex or surrounding soft tissues.[5][6] In the setting of posttraumatic arthritis or advanced degenerative arthritis, anterior ankle impingement that restricts tibiotalar motion and reduces dorsiflexion can lead to an equinus contracture. In patients with neuromuscular disorders such as cerebral palsy, excessive spasticity of the gastrocnemius-soleus complex can lead to an equinus contracture, which is the most common impairment in these patients.[7] Non-neuromuscular etiologies for equinus contracture can be grouped into 3 categories as described by Feraru et al:[8] Acquired: Trauma, neoplasm, infection, burn, and compartment syndrome. Congenital: Hemimelia, phocomelia, and intrauterine stroke. Idiopathic: Sensory integration issues and autism.

A documented increase in the prevalence of ankle equinus has not been observed due to acquired or congenital reasons. However, there is a higher incidence of idiopathic toe walking, an idiopathic cause of ankle equinus, in children with neuropsychiatric or developmental delays, with a slight male predominance in this subgroup. In children aged 5.5, toe walking was observed in 2% of normally developing children and 41% of those with neuropsychiatric or developmental delays.[9][10]

Ankle equinus is characterized by restricted dorsiflexion of the ankle joint, often due to tightness or contracture of the gastrocnemius-soleus complex. This tightness causes an overpull of the Achilles tendon, limiting the ankle's upward movement toward the shin. The reduced dorsiflexion alters normal gait mechanics, leading to compensatory movements that place additional stress on the foot, ankle, and other joints. Over time, these altered biomechanics can result in pain, deformities, and other musculoskeletal issues.

An ankle equinus contracture diagnosis can be made solely on a physical examination. However, a thorough medical history and comprehensive physical examination are essential to determine the underlying cause and appropriate treatment options for a patient with an ankle equinus contracture. Special attention should be given to any history of neuromuscular or neuropsychiatric disorders, trauma, or diabetes, along with an assessment of the patient's activity level. Many patients with an ankle equinus contracture initially present in childhood due to parental concerns about toe walking or downward-pointing toes. The most common causes of an ankle equinus deformity in pediatric patients are cerebral palsy and idiopathic toe walking. A history of cerebral palsy, congenital or intrauterine abnormalities, autism, or neuropsychiatric disorders should be noted. An increased incidence of idiopathic toe walking is more common in patients with neuropsychiatric diagnoses, making this an important aspect of the medical history.[11] A history of foot or ankle trauma can lead to posttraumatic arthritis or an osseous block to dorsiflexion, contributing to an ankle equinus deformity. Following such trauma, patients are often immobilized, and if immobilized in a plantarflexed position, this may result in contracture of the gastrocnemius-soleus complex, causing an equinus deformity.[12] Patients with diabetes are at risk for diabetic neuropathy, which can lead to neuropathy of the lower extremities, subsequently leading to atrophy of the peroneal nerve, which is responsible for innervating the ankle dorsiflexor muscles. This atrophy causes an imbalance in the pull between the posterior and anterior ankle musculature, resulting in an equinus deformity.[5][13] A thorough orthopedic physical examination should be conducted in patients with ankle equinus, with particular attention to the below-mentioned factors. Inspection: The lower extremity, from the pelvis to the toes, should be examined for any contractures, deformities, or signs of previous trauma that may be contributing to the ankle contracture. Hair loss or glossed-over skin patches should be noted, which may indicate diabetic neuropathy, autonomic dysreflexia, or vascular insufficiency. Palpation: Pulses should be assessed for signs of vascular insufficiency.

Inspection: The lower extremity, from the pelvis to the toes, should be examined for any contractures, deformities, or signs of previous trauma that may be contributing to the ankle contracture. Hair loss or glossed-over skin patches should be noted, which may indicate diabetic neuropathy, autonomic dysreflexia, or vascular insufficiency. Palpation: Pulses should be assessed for signs of vascular insufficiency. If the sensation is compromised, Semmes-Weinstein monofilament testing should be performed.[14] Limb length should be evaluated, and the examiner should check for symmetric iliac crests and popliteal creases. If a limb length discrepancy is suspected, the examiner should measure from the anterior superior iliac spine to the medial malleolus on each extremity. Range of motion: The active and passive range of motion of the knee, ankle, and subtalar joints should be assessed. A Silverskiold test should also be performed.[15] In this test, the examiner assesses ankle dorsiflexion with the knee in both flexed and extended positions. If dorsiflexion is restricted when the knee is flexed, it indicates a tight "heel cord" or Achilles tendon/soleus complex. With the knee flexed, the gastrocnemius is relaxed and should not contribute to the limitation in dorsiflexion. When the knee is extended, the entire gastrocnemius-soleus complex is under tension. The gastrocnemius is at least partially responsible if the ankle cannot be dorsiflexed in this position. Notably, holding the hindfoot, midfoot, and forefoot in a neutral position is important to isolate motion at the tibiotalar joint.[16] Although there is no single defined metric for diagnosing ankle equinus, it is generally accepted that if a patient has less than 5° of dorsiflexion with the knee extended and more than 10° with the knee flexed, this indicates a tight gastrocnemius.[17] If the patient has less than 10° of dorsiflexion with the knee flexed, the entire gastrocnemius-soleus complex is tight. These conditions are sometimes referred to in the literature as gastrocnemius equinus and gastrocnemius-soleus equinus, respectively.[8]

In pediatric patients, imaging is generally unnecessary if idiopathic toe walking is suspected. Imaging may be considered if an equinus contracture is unresponsive to initial conservative management, although further imaging beyond an x-ray is rarely required. If osseous involvement is suspected, an ankle x-ray should be ordered to evaluate the bony architecture and identify potential areas of impingement. A full-length standing lower extremity x-ray can be obtained to assess limb length if there is concern about a limb length discrepancy. If developmental delay is documented or abnormal neurological findings are observed during the examination, magnetic resonance imaging (MRI) of the brain or entire spine should be considered to rule out an upper motor neuron etiology.

Effective treatment of ankle equinus necessitates a comprehensive approach tailored to the underlying cause and severity. Therapeutic options include conservative management and surgical interventions, all aimed at restoring normal ankle function and alleviating symptoms. Conservative Management Conservative management is nonoperative, and treatment continues until the patient can ambulate with a heel-toe gait pattern, maintain adequate balance, and achieve sufficient ankle dorsiflexion. Key components of conservative therapy include: Physical therapy with an emphasis on stretching, strengthening, gait training, and home exercise. Serial casting and ankle-foot orthoses, which are primarily used in pediatric patients with ankle equinus. The goal of casting is to achieve at least 5° of ankle dorsiflexion, after which casting can be discontinued, and a physical therapy and home stretching program should be initiated. For idiopathic toe walking ankle equinus, it is crucial to coordinate physical therapy after the completion of casting to help the patient regain strength that may have diminished during the casting process.[9] Botulinum toxin A injections are used to treat patients with increased spasticity and equinus contractures, particularly in those with cerebral palsy. These injections are typically administered every 4 to 6 months or until they become ineffective. They are most commonly combined with casting or bracing. These injections work by reducing the spastic overpull of the gastrocnemius-soleus complex relative to the anterior leg compartment musculature. Idiopathic Toe Walking Cincinnati Care Guidelines should be referred for the complete treatment algorithm.[9][8] Operative Management Operative management should generally be considered only when conservative options have been exhausted, and the ankle equinus deformity remains refractory to these interventions. This typically involves a soft tissue release of one or more structures, including the Achilles tendon, the gastrocnemius-soleus complex, and/or the posterior ankle capsule. The Silverskiold test, as described previously, helps determine which structure should be released.

Operative management should generally be considered only when conservative options have been exhausted, and the ankle equinus deformity remains refractory to these interventions. This typically involves a soft tissue release of one or more structures, including the Achilles tendon, the gastrocnemius-soleus complex, and/or the posterior ankle capsule. The Silverskiold test, as described previously, helps determine which structure should be released. The possible zones of lengthening are described by Firth et al.[18] Zone 1 encompasses the proximal femoral origin of the gastrocnemius to the most distal portion of the medial gastrocnemius muscle belly. Zone 2 is described as being from the distal extent of the medial gastrocnemius muscle belly to the distal end of the soleus muscle. This zone 2 region is commonly defined as the gastrocnemius-aponeurosis soleus fascial complex.[19] Zone 3 is described as the distal aspect of the soleus muscle to the calcaneal tuberosity at the site of the Achilles tendon insertion. Considerations for lengthening procedures of the particular zones include the following: Zone 1: Lengthening at this level focuses on the intramuscular lengthening of the gastrocnemius and soleus musculature, as described by Baumman and Koch.[20] This is typically performed within the fascial interval between the gastrocnemius and soleus muscles. Zone 2: At this level, the gastrocnemius fascia condenses into a broad aponeurotic band that lies superficial to the soleus muscle fascia. Due to the intimate relationship of these 2 layers, differential lengthening of only 1 of these structures is not considered possible.[21] However, proximal to zone 2, at the junction of zones 1 and 2, differential lengthening of the gastrocnemius or soleus fascia is possible, as described by Strayer.[22] Zone 3: Tendo-Achilles lengthening is indicated for refractory ankle equinus when the Achilles tendon is identified as the causative structure. This can be performed through 2 or 3 hemitransections of the Achilles tendon, as initially described by Hoke and White.[23] This procedure can be performed percutaneously or via an open approach. Alternatively, open Z-lengthening of the Achilles tendon is another option.

Zone 3: Tendo-Achilles lengthening is indicated for refractory ankle equinus when the Achilles tendon is identified as the causative structure. This can be performed through 2 or 3 hemitransections of the Achilles tendon, as initially described by Hoke and White.[23] This procedure can be performed percutaneously or via an open approach. Alternatively, open Z-lengthening of the Achilles tendon is another option. In addition to the commonly performed procedures, using a multiplanar external fixator is an option for more complex deformities. This treatment option involves applying an external frame that spans the ankle joint and gradually correcting the deformity with the aid of a computer software program. Typically, this is performed with a hexapod frame with 6 struts, which are elongated and shortened to correct a deformity over weeks to months gradually.[24][25]

The differential diagnosis of ankle equinus involves distinguishing it from other conditions with similar symptoms of limited ankle dorsiflexion and altered gait. Posterior ankle impingement syndrome and tightness of the gastrocnemius-soleus muscle should be evaluated, as both can restrict ankle dorsiflexion. Structural abnormalities, such as talar dome lesions or congenital foot deformities, may also mimic or contribute to the presentation of ankle equinus. If there is a history of trauma, the skeletal structure of the ankle and hindfoot should be assessed to rule out any structural causes of the equinus contracture. Additionally, deficiencies in the range of motion of the hip or knee, or any limb length discrepancy, should be evaluated to ensure they are not contributing to the ankle equinus deformity. The presence of its counterpart, calcaneus deformity, should also be ruled out. Calcaneus gait is characterized by the inverse of ankle equinus, where the triceps surae has decreased power and an inability or reduced ability to plantar flex the ankle.[26]

The prognosis of ankle equinus depends on the causative etiology. In cases of flexible ankle equinus, physical therapy and home stretching programs are often all that is needed to resolve the issue. In cases refractory to conservative management, where operative intervention is required, recurrence is documented. Recurrence rates following gastrocnemius recession range from 10% to 35%.[27][28][29][30] Recurrence rates differ between patients with neuromuscular etiology and those without. Patients with neuromuscular disorders generally have higher recurrence rates. For instance, among those who underwent zone 1 lengthening (Baumann procedure), recurrence of ankle equinus was 24% for patients with a neuromuscular disorder compared to 10% for those without.[29][31]

Complications related to ankle equinus can be categorized into 2 groups based on the type of treatment. Conservative Treatment Complications Conservative treatment for ankle equinus, while generally effective, can be associated with specific complications, as listed below. Serial casting: Pressure sores or ulcer creation. Botulinum toxin A: Overall low complication rate, with an adverse event rate comparable to serial casting.[32] Operative Treatment Complications Operative treatment for ankle equinus can lead to several complications, as mentioned below. Achilles tendon lengthening: Loss of plantar flexion strength. Gastrocnemius-soleus lengthening: Injuries to the lesser saphenous vein and sural nerve and loss of plantar flexion strength. One of the most significant complications of any lengthening procedure for ankle equinus is the development of calcaneus gait and weakness of the gastrocnemius-soleus complex. While a secondary lengthening procedure can address some issues, correcting a weakened ankle plantar flexor complex remains challenging.[18] Evidence suggests that zone 2 or zone 3 lengthening procedures (eg, Strayer procedure or Achilles tendon lengthening) may result in greater postoperative dorsiflexion but are associated with a higher incidence of calf muscle weakness compared to zone 1 lengthening procedures (eg, Baumann procedure).[33]

Patients with ankle equinus often require multidisciplinary consultations to ensure comprehensive care. A referral to a podiatrist or orthopedic surgeon is essential for evaluating the severity of the condition and determining whether surgical intervention is necessary. Physical therapy consultations are crucial for developing a tailored rehabilitation program that includes stretching and strengthening exercises to improve dorsiflexion and overall mobility. If the equinus is related to a neurological condition, collaboration with a neurologist may be needed to address underlying spasticity or other contributing factors. Additionally, consultations with a pain management specialist can benefit patients experiencing significant discomfort.

Deterrence and patient education are critical in managing and preventing the progression of ankle equinus. Educating patients about the importance of regular stretching exercises, particularly for the calf muscles, can help maintain or improve ankle dorsiflexion and reduce the risk of developing equinus. Patients should also be informed about potential causes of ankle equinus, including improper footwear, prolonged immobilization, and underlying medical conditions. Factors such as diabetes, arthritis, morbid obesity, cerebral palsy, autism, or a history of trauma to the ankle can increase the likelihood of conservative treatment failure and may necessitate referral to a specialist. Emphasizing the need for early intervention when symptoms arise can prevent complications and improve outcomes. Educating patients on proper footwear choices, activity modifications, and the importance of regular follow-up visits with healthcare professionals can empower them to actively manage their condition. In cases refractory to conservative management, coordinating with a specialist is essential to tailor an effective treatment plan.

Ankle equinus is a clinical diagnosis, and patients may present with varying degrees of deformity. Pediatricians or primary care providers are typically the first to evaluate and manage these cases. Coordinating care with specialists on an individual basis is crucial, as early recognition and multidisciplinary management significantly improve patient outcomes. Podiatrists and orthopedic surgeons offer specialized assessments and surgical interventions when needed, while physical therapists create targeted rehabilitation programs to enhance ankle mobility and strength. Neurologists and pain management specialists provide crucial insights, particularly when equinus is linked to neurological disorders or chronic pain. Collaboration among these healthcare professionals ensures comprehensive care, addressing all aspects of the patient’s condition from diagnosis and treatment to ongoing management and prevention. This team-based approach integrates diverse perspectives and expertise, enhancing the quality of care and improving patient outcomes. Coordinating care with orthotists, physical therapists, and gait mechanics engineers is essential when indicated. A survey of general and pediatric orthopedic surgeons treating patients with cerebral palsy and ankle equinus contractures found that 87% of respondents used clinical gait assessments in their management, and nearly 25% referred patients to rehabilitation specialists for orthotic needs.[34] Maintaining open communication with ancillary services such as physical therapy, orthotics, and gait mechanics engineers is crucial to the overall care of patients with equinus contractures and enhances the effectiveness of the interprofessional team.