July 2011 Case of the Month. By Matt Grady, MD

Transcription

1 July 2011 Case of the Month By Matt Grady, MD CC: Knee Pain - Osteochondritis Dissecans or not? A Case Comparison HPI: The first patient is a 12 year old female swimmer with right knee pain. The pain started a few months prior to presentation. Pain is made worse with activity specifically swimming breast stroke kick and flutter kick while racing. It is improved with rest. There has not been a history of previous trauma. She also has some pain with running. She has not had any decreased ROM, swelling, locking, catching, giving way, redness, warmth, or paraesthesias In reviewing her history, there are no unexplained constitutional symptoms including rashes, fevers, weight loss or night time pain. NKDA No medicines She is pre-menarchal The remaining medical, surgical, family and social history are noncontributory with no history of autoimmune arthritis, osteochondritis dissecans or joint disease. Physical Exam: Temperature 98.1 F (36.7 C), temperature source oral, height m (5' 1.26"), weight 54.3 kg (119 lb 11.4 oz). Constitutional: Well developed, well nourished, No acute distress LE: Pelvis: There is no pain to palpation about the pelvis. Hips: Symmetric range of motion. There is no pain with internal or external rotation. Popliteal Angles: 45 R, 45 L Thomas test: negative Ely test: negative Thigh: no muscle atrophy, normal muscle strength KNEE Right knee Inspection: Normal alignment Effusion: none Ecchymosis: none Soft Tissues normal

2 Palpation: Tenderness: Yes: Medial Patellar Facet and medial femoral condyle Crepitus: no Masses: Absent Range of Motion: normal Special Tests: Patellar Apprehension: Negative Patellar Compression: Negative Valgus and Varus Stress: No Laxity Lachman and Posterior Drawer: Firm End Point McMurray: Negative Wilson's test: Negative Squat: Patient able to do one leg squat with pain. Knee goes into valgus. Leg Inspection: Calf Atrophy Absent Dorsiflexion with knee extended: 0 R 0 L Ankle and contralateral knee exam otherwise normal Neurovascular: Sensation is intact in the Common Peroneal, Tibial and Saphenous nerve distributions with brisk cap refill Gait: reciprocal with no presence of antalgia RADIOGRAPHS:

3 Radiologist's report: The soft tissues are normal. There is normal mineralization and alignment of the bones. There is a smooth 1.2 x 1.5 x 0.7 cm subchondral defect in the lateral aspect of the distal medial femoral epicondyle, compatible with osteochondritis dissecans (OCD). No loose bodies are seen. MRI: radiologist report (outside adult institution) early OCD vs ossification variant Case 2: left knee pain 10 year old male presents for a 2nd Opinion of left knee pain. The pain started 5/27/11. He twisted his knee awkwardly at ice hockey. He had lateral knee pain, no effusion. X-

4 rays showed a possible OCD. MRI showed a reported OCD. Pain resolved in a few days. No pain today. There has not been a history of previous trauma. He has not had any decreased ROM, swelling, locking, catching or painful popping Site of initial evaluation: outside ortho Initial evaluation and treatment included: x-rays and MRI. In reviewing his history, there are no unexplained constitutional symptoms including rashes, fevers, weight loss or night time pain. His full medical, family, and social history and complete ROS are otherwise unremarkable and non-contributory NKDA, No meds Physical Exam: Height m (4' 8.77"), weight 36.7 kg (80 lb 14.5 oz). Constitutional: Well developed, well nourished, No acute distress LE: Pelvis: There is no pain to palpation about the pelvis. Hips: Symmetric range of motion. There is no pain with internal or external rotation. Popliteal Angles: 30 R, 30 L Thomas test: negative Thigh: no muscle atrophy, normal muscle strength KNEE Left knee Inspection: Normal alignment Effusion: none Ecchymosis: none Soft Tissues normal Palpation: Tenderness: No Crepitus: no Masses: Absent Range of Motion: normal Special Tests: Patellar Apprehension: Negative Patellar Compression: Negative Valgus Stress: No Laxity Varus Stress: No Laxity

5 Lachman: Firm End Point McMurray: Negative Posterior Drawer: Firm End Point Wilson's test: Negative Squat: Patient able to do one leg squat without pain. Leg Inspection: Calf Atrophy Absent Neurovascular: Sensation is intact in the Common Peroneal, Tibial and Saphenous nerve distributions with brisk cap refill Gait: reciprocal with no presence of antalgia Radiographs: Only MRI is present today DDX: Ossification variant vs Osteochondritis Dissecans Lesion Discussion: Irregular ossification of the distal femoral epiphysis is common in young children. In very young children, the epiphysis develops as a secondary ossification center. It starts as a spherical ossification center in the center of the epiphysis that gradually enlarges. The bony epiphysis continues to enlarge by enchondral ossification. Occasionally

6 several secondary foci start and merge into one. Towards the end of early childhood the margins of the epiphysis are frequently irregular or fragmented. MRI s in 11 yo boys with irregular margins have demonstrated a thick overlying cartilage in the areas of irregularity suggesting incomplete ossification rather than bony injury. The normal irregular margins of the distal femoral epiphysis resolve by about 11 in girls and 13 in boys. The lateral femoral condyle (44%) was found to be more likely to be irregular than the medial femoral condyle (12%) in healthy asymptomatic individuals (ages 3-13) (1). Unlike an ossification variant, Osteochondritis Dissecans (OCD) is a pathological injury. It is a focal injury to the subchondral bone. While the cause appears to multifactorial, repetitive microtrauma is likely the cause of some of the injuries. In the developing (open physis) skeleton, it is a potentially reversible condition. If it progresses, it can lead to delamination of articular cartilage with loose body formation and permanent disability (2) Seventy five (75%) percent of cases of OCD of the knee are located in the posterolateral aspect of the medial femoral condyle, often extending into the intercondylar region. The lateral condyle is involved in 20% of patients and both knees are affected in one third of patients. The peak incidence is around 12 to 13 years of age. (1) Traditional grading of OCD has included location on x-ray findings (3), MRI pattern (4) and arthroscopic (5) findings Location of lesion (3).

7 Anderson MRI staging (4): Stage Evaluation Findings I Early Subchondral bone flattening in the epiphyseal plate before growth plate closure IIA Stable Subchondral cyst present IIB III IV Unstable Unstable Terminal Incomplete separation of the osteochondral fragment due to repetitive trauma Effusions (fluid around an undetached, undisplaced osteochondral fragment) Complete separation (detachment) of osteochondral fragment(s); mechanical irregularities and formation of loose bodies Cheng arthroscopic staging of osteochondritis dissecans (6) Grade A B C D E F Findings Articular cartilage is smooth and intact but may be soft or ballottable Articular cartilage has a rough surface Articular cartilage has fibrillations or fissures Articular cartilage with a flap or exposed bone Loose, nondisplaced osteochondral fragment Displaced osteochondral fragment Recent MRI criteria (6) in European countries published in 2011 has suggested several factors associated with pathological development of osteochondritis dissecans rather than delayed ossification. Age, location, the presence of edema and lesion angle were important variables in the evaluation of knee MRI s.

8 Age: OCD did not occur in children younger than 8 years old. Ossification variability did not occur in girls >10 years old and boys >13 years old. Ossification variability was not seen in patients with 10% or less residual physeal cartilage. OCD was rare in patients with 30% or greater residual physeal cartilage. Location: Ossification variability was located in the posterior third of the femoral condyle. OCD occurred most commonly in the middle third. Intracondylar extension was seen in OCD and not in ossification variability. Edema: Perilesional edema was very common with OCD and absent with ossification variability. Lesion angle: Lesion angle <105 was a feature of ossification variability. Based on the above criteria, the 12 yo female with subchondral bone flattening and surrounding bone edema of the medial femoral condyle was treated as an early OCD lesion. She was treated with 6 weeks immobilization followed by 6 weeks of PT as per a modified (Ganley) protocol developed by Kocher and Ganley (2). The 10 yo male with no surrounding bone edema and a thick cartilage articular surface on the lateral femoral condyle was treated as an ossification variant. He is currently asymptomatic and is scheduled to return for a 6 months repeat x-ray check. References: Kocher MS, Tucker R, Ganley TJ, Flynn JM, Management of Osteochondritis Dissecans of the knee: Current Concepts Review, Am J Sports Med : Green WT, Banks HH. Osteochondritis dissecans in children. J Bone Joint Surg. 1953;35A: Anderson IF, Crichton KJ, Grattan-Smith T, Cooper RA, Brazier D (September 1989). "Osteochondral fractures of the dome of the talus". Journal of Bone and Joint Surgery (American) 71 (8): PMID Cheng MS, Ferkel RD, Applegate GR (1995). Osteochondral lesion of the talus: A radiologic and surgical comparison. New Orleans, LA. Paper presented at Annual Meeting of the Academy of Orthopaedic Surgeons. 6. Jans LB, Jaremko JL, Ditchfield M, Huysse WC, Verstraete KL. MRI differentiates femoral condylar ossification evolution from osteochondritis dissecans. A new sign. Eur Radiol Jun;21(6): Epub 2011 Jan 26.