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Ankle OCD

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Description

Osteochondritis dissecans (OCD) is a localized injury or condition affecting an articular surface that involves separation of a segment of cartilage and subchondral bone (Schenck, 1996).  The ankle joint is the most commonly injured joint in athletes, and OCD lesions primarily are found in the ankle (Giovanni et al, 2007). Lateral talar lesions are more common than medial lesions.  Most lateral lesions of the talus are associated with trauma, whereas medial lesions may have a familial history and may be bilateral.

Structure and function

The ankle, or tibiotalar joint, is vital for normal function of the lower limb, including walking and running.  These joint surfaces are highly conforming, which allows weight-bearing forces to spread out over a broad area and minimize joint pressures.  Alteration in these conforming surfaces can dramatically decrease contact area and increase pressure, leading to arthritis (DiGiovanni et al, 2007).  Muscles, tendons, and contact surfaces (tibial plafond and talus) work together to establish different contact points during the gait cycle. Ankle injuries may predispose or alter one of these components, therefore compromising the synergistic weight-bearing distribution of the ankle joint.

Articular hyaline cartilage provides an ideal structure for weight-loading. Composed of water, proteoglycan, and collagen, the mixture of fluid and matrix provides viscoelastic and mechanical properties for efficient load distribution.  Hyaline cartilage is relatively avascular, which presents a healing and repair challenge for articular lesions of a joint.

Epidemiology

Osteochondral injuries of the ankle are being recognized as an increasingly common injury that may occur in up to 50% of acute ankle sprains and fractures (Sexena et al, 2007). The average age of patients with an osteochondral lesion (OCL) is 20-30 years, with a male preponderance of 70%. Bilaterality of the lesions is reported in 10% of cases (Chew et al, 2008).  After the acute symptoms associated with a reported ankle injury or trauma, individuals may develop limited walking tolerance, chronic pain, instability, and swelling of the ankle, which can lead to significant loss of function and disability.

Clinical presentation

Patients usually present after an associated ankle injury, such as a sprain, strain, or fracture.  These injuries can be the result of combined inversion and dorsiflexion forces impacting the ankle.  An inability to bear weight following the injury, with associated swelling, bruising, and pain, is common.

Although most patients with osteochondral lesions complain of ankle pain after a traumatic event, other patients may present with chronic ankle pain without a recalled injury.  Complaints of persistent swelling, instability, pain, and stiffness of the affected ankle are common.  Activities such as stair climbing, jumping, high-impact activities, and prolonged walking may exacerbate the symptoms.

Physical exam findings commonly include joint effusion, tenderness to palpation over medial, and lateral joint lines/periarticular surfaces.  Decreased strength and irritation of symptoms with range of motion is common.  Noting the overall alignment of the injured and non-injured side can also be important.  Range of motion of the other joints of the lower extremity, including knee and subtalar, can also be helpful.  An anterior drawer test of the ankle can assist in delineating any associated signs of instability or ligamentous laxity.

Theories exist about the causes of a patient’s predisposition to OCD lesions.  Those individuals with a family history, degenerative joint diseases, or metabolic/endocrine disorders may also present with mono- or polyarticular symptomology.

Red flags

Persistent symptoms of instability, swelling, and pain following an ankle injury should be referred to a specialist (orthopedic surgeon/sports medicine specialist) for evaluation.  Any chronic pain without injury and constitutional symptoms or history of bone/musculoskeletal tumors should also be referred for evaluation.

Differential diagnosis

The differential diagnosis includes avascular necrosis of the talus and acute osteochondral fracture.  In younger patients (children and adolescents), the radiographic findings may be associated with apophysis (growth plate) development. In older individuals, there may be an associated insufficiency fracture.

Objective evidence

The best place to start is with standard weight-bearing radiographs of the affected ankle — anterior/posterior, lateral and oblique views.  Weight-bearing films are important because they allow for observation of the appearance of the joint in a loaded position. If there is suspicion of bilateral ankle symptoms, obtain radiographs of both sides for comparison. A unique view, the Canale view, can also assist in viewing the subchondral surface. This x-ray is taken with the foot pronated to 15 degrees and the x-ray beam aimed 75 degrees toward the patient's head. Based on its appearance on plain radiographs, the OCD lesion can be staged using the Berndt and Hardy classification.

Computed tomography (CT) scan can be helpful in assessing the extent of bony injury, the size and shape of the lesion, and displacement. Assessing cartilage with CT scanning, however, remains a challenge.

The gold standard for OCD diagnosis is magnetic resonance imaging (MRI), which has been shown to detect bone bruises, cartilage damage, and other soft tissue insults (O’Loughlin et al, 2010). Specific sequences, such as T2-weighted MRIs, can help to differentiate zones of cartilage involved in the lesion.

Some patients will require laboratory tests related to endocrine and metabolic bone disorders, such as individuals with bilateral symptoms or a family history of osteochondral lesions.

Risk factors and prevention

Individuals with a genetic predisposition or a metabolic or endocrine disorder may be a risk for developing OCD lesions.  Long-term steroid use and associated fractures of the ankle may also put individuals at risk for altered blood supply and cartilage surface, which may predispose them to injury.

The key to prevention of chronic symptoms of ankle pain is recognition of ankle injury patterns and appropriate treatment.  Individuals with repetitive injuries are at higher risk for the developing an OCD lesion; therefore, limiting activities or utilizing bracing/physiotherapy may help to prevent further injuries.

Treatment options

There are two types of treatment: non-operative and operative.

Non-operative Treatment

Non-operative treatment may be appropriate for patients with an incidental finding of OCD on x-ray.  Pediatric patients with low-grade osteochondral lesions can be treated successfully with protected weight-bearing.

Interventions such as rest, restriction of sports or high-impact-related activities, and use of non-steroidal anti-inflammatory drugs have resulted in better outcomes than placing individuals with injured ankles in in a cast. Patients who are asymptomatic or minimally symptomatic with lesions that involve cartilage alone may be treated with rest, ice, immobility, and an orthosis. Several studies have demonstrated spontaneous healing of OCDs in adult patients. However, there is evidence of relatively high rates of failure with non-operative management of OCDs in adults (O’Loughlin et al, 2010).

Operative Treatment

The aim of surgical treatment is revascularization of the bony defect. There are several options available:

  • Cartilage stabilization/pinning
  • Retrograde drilling
  • Microfracture/microdrilling
  • Tissue transplantation

The unique challenges of recreating the biomechanical properties of articular cartilage and resorting the joint surface for weight-bearing to normal remains an ongoing area of interest. Retrograde drilling and microfracture have been demonstrated to have good symptom relief, depending on the OCD lesion and patient characteristics.

In some series, tissues transplantation has been reported to improve symptoms and overall quality of life scores in individuals with larger OCD lesions.

Outcomes

With appropriate recognition and non-operative/operative intervention, symptoms of pain and disability relating to life quality can be addressed.  Unfortunately, a large number of individuals may progress to altered joint mechanics and increased timing of osteoarthritis of the ankle joint, requiring additional treatment and intervention.

Holistic medicine

Ankle instability and associated symptoms of ankle OCD lesions can lead to significant disability and emotional distress. Because this is a common injury in athletes, many athletes are forced to decrease their high-impact activities and alter training and sports participation schedules to address this injury.

Miscellany

  • Other common locations of OCD lesions include the knee and the elbow.
  • Remember to scan all parts of the x-ray for suspicious lesions.  Don’t just look for a fracture.  Look for alterations in the joint line and identify alterations in the joint surfaces visible on x-ray.
  • Ankle sprains may impair a patient for acute periods. If the pain and symptoms persist, keep assessing the patient, or refer the patient to another specialist for evaluation.
  • Patients may read on the Internet about new treatments for OCD lesions. Although ideas are being generated to treat these lesions, many lack concrete long-term evidence for success.

Key terms

Loose body, talar dome lesion

Skills

  • History taking – description of injury vs. presentation of symptoms – does this make sense?
  • Physical exam of the ankle
  • Anterior drawer test
  • Interpretation of plain radiographs of the ankle joint

References

DiGiovanni C, Greisberg J. (2007). Foot and ankle: Core knowledge in orthopedics. Elsevier Mosby: Philadelphia, PA.

O'Loughlin P, Heyworth B, Kennedy J. Current concepts in the diagnosis and treatment of osteochondrol lesions of the ankle. The American Journal of Sports Medicine, 38 (2): 392-404, 2010.  

Schenck R, Goodnight J. Current concepts review osteochondritis dissecans. The Journal of Bone and Joint Surgery, 78-A (3): 439-456, 1996.