Osteochondritis Dissecans

Osteochondritis Dissecans

Description(1)(2)(4):

Osteochondritis Dissecans (OCD) is a common, yet poorly understood cause of knee pain in the pediatric and juvenile population as well as an adult form that can occur in the developed skeleton.  The incidence and prevalence is currently unknown as many of the lesions remain asymptomatic in both athletic and non-athletic individuals. It can most commonly found in the knee but is also present in other bones. OCD has recently been redefined as a “focal, idiopathic alteration of subchondral bone with risk for instability and disruption of adjacent articular cartilage that may result in premature osteoarthritis”.

Pathophysiology(1)(2)(4):

The underlying pathophysiology of OCD remains elusive to clinicians and researchers. The initial theory hypothesized the role of inflammation, however this has been unsupported by further research. Current studies suggest possible etiologies/mechanisms such as, hereditary, repetitive microtrauma and vascular insufficiency. Furthermore, a pathoanatomic cascade has been proposed:
Softening of the overlying articular cartilage with intact articular surface → Early articular cartilage separation → Partial detachment of lesion → Osteochondral separation with loose bodies.

Anatomy(1)(2)(4):
▪ Components of OCD lesion:
Parent bone
Progeny fragment – lesions that could become unstable or detached
▪ Location:
a. Knee (most common)
i. Posterolateral aspect of the medial femoral condyle (64% of knee OCDs)
ii. Lateral femoral condyle (32% of OCDs)
iii. Patella
b. Elbow (Figure 1-3 – Elbow anatomy – Netter (8), elbow athroscopy surface and intraarticular anatomy (9))

Figure 3 – Elbow Arthroscope anatomy

Co – Coronoid, Cap -Capitellum, RH – Radial head
i. Trochlea
ii. Capitellum
Figure 4 – Sportmedschool – Osteochondral defect capitellum

(see Figures 5,6 Capitellar Osteochondritis Dissecans under arthroscopy
courtesy of Dr. Duong Nguyen http://www.nguyensportsmed.com/Pages/default.aspx)

c. Talus

Classification(1):
▪ Type I: Depressed osteochondral fracture
▪ Type II: Fragment attached by osseous bridge
▪ Type III: Detached non-displaced fragment
▪ Type IV: Displaced fragment

Clinical Presentation(1)(2)(4):
History:
– Four times more common in males than females
– Bilateral in 10-20% of cases
– Usually highly active athlete
– No specific injury mechanism identified
Symptoms:
– Gradual onset of vague, poorly localized, aching pain
– Duration: days to weeks
– Worse during activity
– Intermittent swelling
– Mechanical symptoms (more advanced disease)

Differential Diagnoses(4):
▪ Very broad and dependent on location of knee pain
▪ OCD usually presents with anterior knee pain.
▪ Other potential causes of anterior knee pain include:
Hoffa syndrome
Idiopathic anterior knee pain
Osgood-Schlatter disease
Singing-Larden-Johannson syndrome
Infrapatellar bursitis
Prepatellar bursitis
Patellar tendonitis
Patellar stress fracture
Plica syndrome
Quadriceps tendonitis

Physical Examination(1)(2)(4):
Inspection
+/- effusion
Palpation
Localized tenderness
Range of motion
Mild to severe restriction of ROM dependent on stage of disease
Locking (intra-articular loose body)
Special tests:
Wilson’s test (specific to medial femoral condyle lesion)
Figure 7: Wilson’s Test. Flex the knee (a) and internally rotate the foot (b) extend the knee fully (c).(5)

Pain with internally rotating the tibia during knee extension between 90 and 30, then relieved with external rotation

Investigations(1)(2)(4):
▪ X-Ray (bilateral)
Weight-bearing AP and lateral
Tunnel (notch) view (30-50 knee flexion) – Figure 8, 9 AP v. Tunnel view same patient

Figure 8 – AP view

Figure 9 – Tunnel View (same patient)

Identifies lesions on posterior aspect of femoral condyles
Lower-extremity alignment: assess underlying malalignment
Skeletal age assessment: useful in surgical planning and prognosis
MRI
Characterizes the lesion further
Size
Status of subchondral bone and cartilage
Signal intensity surrounding lesion
Presence of loose bodies
Less specific in skeletally immature patients

Figure 10: Plain X-ray showing osteochondritis dissecans lesion of the medial femoral condyle, as a radiolucent area[6]

Figure 11: MRI showing osteochondritis dissecans lesion of the medial femoral condyle[7]

Management(1)(3):
Patients are divided into four subclasses:
1.  Skeletally immature patients with stable lesions
2.  Skeletally immature patients with unstable lesions
3.  Skeletally mature patients with stable lesions
4.  Skeletally mature patients with unstable lesions

Non-Operative Treatment:
– Restrictive weight-bearing and bracing
– Symptomatic treatment
– Indications:
Skeletally immature patients with stable lesions
asymptomatic adults
Outcome:
50-75% heal without fragmentation

Operative Treatment:
– Diagnostic arthroscopy
– Impending physeal closure
– Clinical signs of instability
– Expanding lesions
– Failed non-operative management
– Subchondral drilling with K-wire
– Leads to formation of fibrocartilaginous tissue
– Improved outcomes in skeletally immature
– Fixation of unstable lesion
– Chondral resurfacing (lesions >2cm x 2cm)
– Knee arthroplasty (>60 years old)
▪ AAOS Clinical Practice Guidelines provide few conclusive recommendations on the diagnosis and treatment of OCD
▪ Many different evaluation and treatment modalities have been used, few in a prospective, randomized manner

Figure 12: Pre and postoperative X-Ray and MRI[3]

Prognosis(1):
Better prognosis:
–  Younger age
–  Open distal femoral physes (best predictor for non-op management)
–  Medial femoral condyle

Worse prognosis:
– Adult form
– Lateral femoral condyle
– Sclerosis on X-Ray
– Synovial fluid behind lesion on MRI

Author: Alessandro Francella, MD (August 29, 2017 PR ND)

References:
1. Karadsheh, M. Osteochondritis Dissecans. Retrieved from: http://www.orthobullets.com/sports/3028/osteochondritis-dissecans.
2. Nepple JJ, Milewski MD, Shea KG. The Journal of Knee Surgery. 2016; 29(07): 533-538.
3. Chambers HG, Shea KG, Carey JL. AAOS Clinical Practice Guideline: diagnosis and treatment of osteochondritis dissecans. J Am Acad Orthop Surg 2011; 19 (5) 307-309
4. Patel DR, Villalobos A. Evaluation and management of knee pain in young athletes: overuse injuries of the knee. Translational Pediatrics. 2017 Jul; 6(3): 190–198.
Images:
5. Retrieved from: https://www.arthritisresearch.us/rheumatoid-arthritis/additional-investigations.html
6. Retrieved from: https://www-ncbi-nlm-nih-gov.myaccess.library.utoronto.ca/pmc/articles/PMC5532199/figure/f2/
7. Retrieved from: http://www.orthobullets.com/sports/3028/osteochondritis-dissecans

8.  Netter, F Atlas of Human Anatomy 2nd Edition Novartis, 1997
9.  http://www.nguyensportsmed.com/Pages/Elbowarthroscopy.aspx