AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Background

Osteochondritis dissecans (OCD), by definition, is a disorder of one or more ossification centers, characterized by sequential degeneration or aseptic necrosis and recalcification. OCD lesions involve both bone and cartilage. These lesions differ from acute traumatic osteochondral fractures; however, they may manifest in a similar fashion. OCD lesions also must be differentiated from meniscal pathology. OCD causes 50% of loose bodies in the knee. The etiology of these lesions is multifactorial, including trauma, ischemia, abnormal ossification centers, genetic predisposition, or some combination of these factors. Little agreement exists among researchers regarding the etiology of OCD.

In 1558, Ambroïse Paré removed loose bodies from a knee joint. In 1870, Paget described quiet necrosis within the knee. In 1888, König coined the term "osteochondritis dissecans." He proposed this condition was caused by spontaneous necrosis due to trauma.

With the advent of roentgenography, osteochondrotic conditions in other joints, primarily the hip, were recognized. In 1910, Legg, Calvé, and Perthes independently identified a condition of the hip joint in children, which is now known as Legg-Calvé-Perthes disease. In 1921, Waldenström introduced the term coxa plana (ie, disintegration of capital femoral epiphysis.)

Since the introduction of radiography, 50 additional anatomic sites within the body where OCD can occur have been identified.

Frequency

United States

• The average age at presentation is 10-20 years, but OCD may occur in persons of any age group.



• The male-to-female ratio is 2-3:1.



• Bilateral involvement is noted in 30-40% of cases.



• In 85% of cases, lesions are observed on the medial femoral condyle (MFC) of the knee; 15% of cases are observed on the lateral femoral condyle. Of the MFC lesions, 70% occur in the posterolateral aspect.



• Of patients with OCD, 21-40% have some history of trauma.

International

In Sweden, prevalence is reported at the following levels:

• In skeletally immature patients, 150 cases per 250,000 people are reported.



• In skeletally immature female patients, 18 cases per 100,000 people are reported.



• In skeletally immature male patients, 29 cases per 100,000 people are reported.

Functional Anatomy

In skeletally immature individuals, the vascularity to epiphyseal bone is very good, supporting both osteogenesis and chondrogenesis. With disruption of the epiphyseal vessels, varying degrees and depth of necrosis occur, resulting in a cessation of growth to both osteocytes and chondrocytes. In turn, this pattern leads to nonspecific changes that produce disordered enchondral ossification, resulting in subchondral avascular necrosis or OCD.

Four stages of OCD have been identified, including revascularization and formation of granulation tissue, osteoclasis of necrotic fragments, intertrabecular osteoid deposition, and remodeling of new bone. With delay in the revascularization stage, an OCD lesion develops. OCD lesions may lead to articular-surface irregularities, which can cause degenerative arthritic changes.

Sport Specific Biomechanics

A proposed cause of OCD is an anatomic variation allowing the lateral aspect of the femoral condyle to abut the tibial spine, leading to repetitive localized epiphyseal microtrauma with osteochondral separation and subsequent OCD. This pattern may lead the patient to walk with the tibia externally rotated to avoid this abutment.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

History

• Symptoms are usually vague and poorly localized.



• A vague ache within the knee, with possible clicking or popping, may be reported.



• Varying degrees of pain, swelling, and stiffness are reported.



• Symptoms may be associated with activities (eg, sports, activities of daily living).



• With complete fragment separation, locking symptoms may occur.



• Prolonged symptoms lead to progressive degenerative arthritis.



• Giving way of the knee may occur secondary to quadriceps weakness.

Physical

• Effusion may be present.



• Quadriceps atrophy and weakness may be evident.



• Occasionally, a loose body may be palpable.



• The patient may lack full knee extension compared with the contralateral knee.



• Tenderness is noted over the lesion.



• Evaluate gait for external rotation of the tibia.



• Perform the Wilson test to check for OCD. The examiner flexes the knee to 90° while internally rotating the tibia. A positive Wilson sign occurs when pain is elicited at 30° of flexion and is relieved with external rotation.

Causes

• The 2 distinctive subsets of patients are skeletally immature patients and skeletally mature patients.



• Little agreement exists among researchers regarding the etiology of OCD. Possible etiologies include the following:
  
  
  • Trauma
  
  
  
  • Skeletal maturation (accessory centers of ossification)
  
  
  
  • Vascular causes/ischemia
  
  
  
  • Genetic conditions (eg, multiple epiphyseal dysplasia)
  
  
  
  • Metabolic factors
  
  
  
  • Hereditary factors
  
  
  
  • Anatomic variation

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Other Problems to be Considered

Chondral fracture
Osteophytes
Synovial chondromatosis

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Imaging Studies

• Plain radiography (anteroposterior, lateral, and tunnel views) shows OCD lesions as well-circumscribed crescent-shaped areas of radiolucency above an area of subchondral bone, separated from the femoral condyle. In 75% of cases, the lesion is located on the posterolateral aspect of the MFC.



• Arthrography, which is not used routinely, may be helpful but is invasive; MRI can obtain similar data.



• Bone scanning may be helpful with a high index of suspicion or in patients with occult bilateral involvement; however, it cannot determine the age of the lesion.



• With gadolinium enhancement, MRI is helpful for determining the vascularity of the lesion, for determining whether involvement is bilateral, and for determining if smaller lesions are present. MRI also helps determine the degree of loosening of the lesion. MRI is helpful in determining appropriate treatment and tracking the extent of healing.



• CT scanning may helpful in determining the appropriate treatment and is used when MRI is unavailable or contraindicated.

Procedures

• Knee arthroscopy can be used as a diagnostic tool and a therapeutic tool. Results of arthroscopic evaluation allow determination of the size and stability of the lesion and allow tracking the lesion for evidence of healing. In addition, arthroscopic treatment of OCD, by whatever means, is possible and avoids formal knee arthrotomy.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Acute Phase

Medical Issues/Complications

Important variables affect the choice of treatment. The general rule is the younger the patient, the better the prognosis. Guidelines for treatment are outlined by the following categories:

• Category 1 (ie, girls younger than 11 y, boys younger than 13 y): These patients usually do well with nonoperative treatment.

• Category 2 (girls aged 11-15 y, boys aged 13-17 y): These patients are near skeletal maturity. Treatment depends on the looseness of the lesions.

• Category 3: Physeal closure and skeletal maturity have occurred. Treatment is based on the size and stability of the lesion.

• Grade 1 - Positive radiography findings and an intact articular surface

• Grade 2 - Articular injury noted at arthroscopy

• Grade 3 - Loose lesion (stays within crater)



• Grade 4 - Loose fragment within joint

Surgical Intervention

Arthroscopy versus open treatment

• Arthroscopy is preferred so that arthrotomy can be avoided.
  
  
  • Drilling of the defect may be performed, with the hope that revascularization will occur.
  
  
  
  • Pinning may be performed to stabilize the fragment. Stainless-steel pins usually require removal to avoid additional chondral injury. Resorbable pins can be used to avoid the need for removal; however, they may not be rigid enough or may not last long enough to allow healing.
  
  
  
  • Excision of the fragment and removal of loose bodies may be necessary.
  
  
  
  • Screw fixation may be performed for fragment stabilization. In this method, usually a specialized screw or Herbert-type screw is used.
  
  
  
  • Osteochondral autograft transplantation (OATS) involves harvesting cylindrical osteochondral grafts from other areas of the knee to reconstruct a weight-bearing surface. A maximum 1-cm lesion (crater) depth is allowed for use of this treatment method.
  
  
  
  • Osteochondral allograft transplantation is similar to OATS except that a freshly harvested allograft condyle is used. The advantages are that the exact condyle curvature can be reconstructed and no further defect is created during autograft harvest.
     
• Autologous chondrocyte implantation (ACI), by Carticel, requires a diagnostic arthroscopy, harvesting of a small amount of cartilage cells for cloning, and subsequent arthrotomy for reimplantation. Bone grafting of the OCD crater is often necessary prior to implantation.

Other Treatment

• In children with nondisplaced fragments, initial treatment includes limitation of activity with the use of crutches and restricted range of motion (eg, knee immobilizer, range-of-motion brace).

• Recommend a trial of nonoperative treatment for 3-6 months. If symptoms persist or failure to unite is observed, proceed with surgical treatment

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Treat with pain medication and nonsteroidal anti-inflammatory drugs (NSAIDs) of choice, as indicated, to control pain, inflammation, and swelling.

Drug Category: Analgesics

Pain control is essential to quality patient care. Analgesics ensure patient comfort and have sedating properties, which are beneficial for patients who experience pain.

Drug Category: Nonsteroidal anti-inflammatory drug (NSAID)

Have analgesic, anti-inflammatory, and antipyretic activities. Their mechanism of action is not known, but they may inhibit cyclooxygenase activity and prostaglandin synthesis. Other mechanisms also may exist, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell membrane functions.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Return to Play

Return to play is allowed once the OCD lesion has healed and quadriceps strength has returned to within normal limits. If the athlete was treated surgically, he or she may return to play when the OCD lesion has healed and any obstructive retained hardware has been removed.

Complications

A nonunion of the OCD fragment may occur and progress to dissociation, leading to intra-articular loose body symptoms. This, in turn, may lead to a type of reconstructive procedure such as OATS or ACI (see Surgical Intervention in Acute Phase). Regardless of treatment, degenerative articular changes may develop over time.

Prognosis

The general rule for the prognosis of OCD is the younger the patient, the better the prognosis. The prognosis also depends on the size and severity of the lesion.

MULTIMEDIA

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Media file 1:  Anteroposterior and lateral radiographs of medial femoral condyle osteochondritis dissecans.
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Media file 2:  Anteroposterior MRI of medial femoral condyle osteochondritis dissecans.
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Media file 3:  Lateral MRI of osteochondritis dissecans.
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Media file 4:  Herbert screw stabilization of medial femoral condyle osteochondritis dissecans.
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Media file 5:  Anteroposterior radiograph of medial femoral condyle osteochondritis dissecans.
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Media file 6:  Lateral radiograph of osteochondritis dissecans.
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Media file 7:  Arthroscopic view of medial femoral condyle osteochondritis dissecans, hinged medially. Note the large size and thickness of the fragment.
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Media file 8:  Anteroposterior MRI of medial femoral condyle osteochondritis dissecans, hinged medially.
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Media file 9:  Arthroscopic view of osteochondritis dissecans of the medial femoral condyle. The osteochondral fragment has been elevated from the crater. Note the sclerotic crater with an interposed fibrocartilaginous layer. This lesion has been previously treated with drilling; an old drill hole can be seen faintly at the upper aspect of the crater.
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Media file 10:  Arthroscopic debridement of the osteochondritis dissecans bed to bleeding bone.
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Media file 11:  Replacement of the fragment and temporary Kirschner wire stabilization.
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Media file 12:  Completed osteochondritis dissecans stabilization with 2 Herbert screws. On initial examination, the most lateral defect was comminuted and removed; the larger weight-bearing surface was maintained and stabilized.
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REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

• Andrews JR, Timmerman LA. Diagnostic and Operative Arthroscopy. Philadelphia, Pa: Harcourt Brace & Company; 1997.
• Beaty J. Orthopaedic Knowledge Update 6. Rosemont, Ill: American Academy of Orthopaedic Surgeons; 1999:506-507.
• Browner BD. Skeletal Trauma: Fractures, Dislocations, Ligamentous Injuries. Philadelphia, Pa: WB Saunders Co; 1998.
• Delee JC. Orthopaedic Sports Medicine, Principles and Practice. Vol 2. Philadelphia, Pa: WB Saunders Co; 1994.
• Siliski JM. Traumatic Disorders of the Knee. New York, NY: Springer-Verlag; 1994.

Article Last Updated: Jul 28, 2006