Focal Spontaneous Osteonecrosis and Medial Meniscus Tear: Two Cases and a Literature Review Christopher Brown, BA, and Jeffery L
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A Case Report & Literature Review Focal Spontaneous Osteonecrosis and Medial Meniscus Tear: Two Cases and a Literature Review Christopher Brown, BA, and Jeffery L. Stambough, MD, MBA pontaneous or idiopathic osteonecrosis of the medi- guishing SO from 2nd ON.8 MR and bone scan images are al femoral condyle is a well-recognized cause of commonly used to identify the disease in its early stages, acute pain, tenderness over the joint line, effusion, and plain films are commonly used to rule out advanced and synovitis. Since the disease was first described disease when disease duration is not clear. Radionuclide Sby Ahlback and colleagues1 in 1968, it has been the subject techniques tend to confirm all 4 osteonecrosis stages.8,10,11,16 of several studies. Results from history, examination, and Without early detection, SO treatment can become compli- clinical studies suggest a complicated problem involv- cated by the treatment required for the apparent overlying ing biomechanical and blood supply changes that tend to pathologies (eg, degenerative medial meniscal tears). increase the susceptibility of the medial femoral condyle When patients aged 50 years or older present with acute to avascular necrosis in the presence of meniscal pathol- onset of medially-based knee pain, the most common ogy.2-9 It remains unclear if the focal type of osteonecrosis differential diagnosis includes SO, medial compartment arises from the insult of the arthroscopy or from an under- osteoarthritis, and degenerative medial meniscus pathol- appreciation of the disease in its early stages. ogy. Here we describe 2 cases of SO diagnosed and treated There are 2 types of avascular necrosis in the skeleton. initially as degenerative medial meniscus tears, and we The first, which occurs more commonly in patients aged 50 illustrate the clinical diagnostic features of the disease. years or older, is focal spontaneous osteonecrosis (SO); the second, which tends to occur in patients aged 30 to 50, is CASE REPORTS secondary osteonecrosis (2nd ON). The clinical presentations Case 1 of these types of osteonecrosis must be distinguished when A woman in her early 50s presented to her local orthope- diagnosing and treating patients. SO is associated with ten- dist with left knee pain and swelling that had progressively derness over the joint line, unilateral knee involvement, and worsened over 3 weeks. The patient noted that the pain acute pain exacerbated by increased weight-bearing.4,8,10,11 was exacerbated when walking and standing and partly With SO, most patients can remember the exact moment of relieved at rest. She also complained of sleeping problems, symptom onset, and they describe pain increasing at night or with an occasional increase in pain at night. The patient at rest.1,4,8,10-12 In contrast, 2nd ON generally shows bilateral was 5 feet 6 inches tall, weighed 185 pounds, and was a involvement of multiple joints with gradual onset of diffuse nonsmoker of general good health, except for hypercho- pain.8 Secondary osteonecrosis is commonly associated with lesterolemia. She had a completely benign medical history such predisposing factors as corticosteroid therapy, alcohol- in regard to the knee, which to our knowledge included no ism, and systemic lupus erythematosus.2,5,8,13-15 prior injuries and no corticosteroid steroid treatments. In patients with knee pain, early diagnosis requires a high Physical examination revealed tenderness about the index of suspicion for SO, as the diagnosis may not become medial joint line but not about the medial distal femoral apparent until months or years after symptom onset. condyle. Range of motion was slightly restricted in flexion. Radiography, magnetic resonance imaging (MRI), and The patient had mild patellofemoral crepitus, a small effu- radionuclide bone scanning have proved capable of distin- sion, and diffuse synovitis. The collateral and cruciate liga- ments were intact, and the hip and neurovascular examina- Mr. Brown is Medical Student, College of Medicine, University of tions were normal. She had a positive McMurray sign. Cincinnati, Cincinnati, Ohio. At presentation, weight-bearing plain films showed Dr. Stambough is Consultant, Back and Treatment Center, mild narrowing of the medial joint line and early medial Deaconess Hospital, and Adjunct Professor, Department of Medical and Industrial Engineering, University of Cincinnati, compartmental osteoarthritis, and T2-weighted MR imag- Cincinnati, Ohio. es showed a displaced degenerative tear involving the posterior horn of the medial meniscus with a Baker cyst Address correspondence to: Jeffrey L. Stambough, MD, MBA, measuring 5.0 cm posteromedially (Figures 1A, 1B) and 4600 Smith Road, Suite B, Cincinnati, OH 45212 (e-mail, drst- moderate chondromalacia of the medial compartment [email protected]). with moderate joint effusion, but no evidence of SO. Am J Orthop. 2008;37(2):81-87. Copyright Quadrant HealthCom These images were obtained approximately 3 weeks Inc 2008. before index surgery. February 2008 81 Focal Spontaneous Osteonecrosis and Medial Meniscus Tear A B A B Figure 2. Case 1—postoperative fat-suppressed T -weighted Figure 1. Case 1—preoperative fat-suppressed T2-weighted 2 coronal (A) and sagittal (B) magnetic resonance images show coronal (A) and sagittal (B) magnetic resonance images show posterior horn medial meniscus pathology and no recognizable osteonecrosis and collapse of the medial femoral condyle, evidence of focal spontaneous osteonecrosis of the medial stage IV. femoral condyle. All conservative measures, including physical therapy, Technetium bone scans, also obtained approximately 9 use of nonsteroidal anti-inflammatory drugs, and intra- weeks after surgery, revealed increased uptake at the medi- articular corticosteroid injections, failed to relieve the al joint space. Cultures were negative at this time. patient’s symptoms. Arthroscopy of the knee was then Plain films obtained 6 to 8 months after surgery showed scheduled for approximately 6 weeks after symptom a large osteochondral defect (1.5x1.0 cm) in the medial onset. With the patient under general anesthesia and in femoral condyle involving the weight-bearing portion, the supine position, the surgery was performed with a consistent with SO. There were secondary degenerative 30° videoarthroscopy system. The principal pathology changes, medially of the distal femur and proximal tibia, was located in the medial compartment, where there was with progressive varus deformity. MR images obtained an irreparable complex tear of the posterior horn of the around the same time showed osteonecrosis and collapse of medial meniscus—consistent with the patient’s symptoms. the medial femoral condyle, which fit the clinical pattern of In addition, there was a radial and longitudinal component a stage IV lesion (Figures 2A, 2B). In addition, the patient along with mild chondromalacia of the undersurface of the still had a Baker cyst (4.0x1.0 cm) in the medial aspect of patella, without significant arthritis. The anterior cruciate the knee and severe complete secondary chondromalacia of ligament (ACL) and the lateral meniscus were both intact. both the medial femoral condyle and the medial proximal The patient did not have a chondroplasty, nor were any tibial plateau. No new medial meniscal tear was seen. The electrothermal therapies applied. The procedure proceeded patient was offered an elective left medial total knee arthro- without complications. plasty. The patient declined the procedure and progressed By 9 weeks after surgery, the patient’s knee findings to advanced medial compartment osteoarthritis with varus and pain complaints had not improved but worsened. The deformity and no resolution of pain. patient presented with gradually increasing recurrent medi- ally based knee pain exacerbated by use and relieved at Case 2 rest. Despite prior aspiration and an intra-articular steroid A man in his mid 50s presented with acute and severe medi- injection (triamcinolone acetonide), symptoms persisted. ally-based right knee pain that had progressively worsened Additional physical therapy had not been effective. There over a week. The patient was 5 feet 5 inches tall, weighed was no interval trauma. approximately 250 pounds, and was a nonsmoker with Physical examination revealed thickening and swelling hypertension, generalized osteoarthritis, and severe degen- around the medial joint space (1+ effusion). There was erative disc disease. The disabling pain made weight-bearing no pes anserinus tenderness or neurovascular change. The impossible. There was no recent history of trauma, and the patient did not have any restricted hip motion or gait abnor- patient denied popping, snapping, effusion, bleeding, and malities that would suggest the knee pain was referred from ecchymosis. To our knowledge, he had not undergone any the hip. Range of motion was -5° to +120°. previous knee injury or any form of corticosteroid treatment Plain films obtained approximately 9 weeks after sur- other than the single intra-articular cortisone injection (tri- gery showed mild to moderate osteoarthritis of the patel- amcinolone acetonide) given at presentation, and to which lofemoral joint and mild arthritis of the medial joint space he had not responded. with mild joint space narrowing in the knee. There was Physical examination revealed that the right knee no significant osteophyte formation. Compared with the pain was localized along the medial collateral ligament right knee joint space, the left showed a 50% reduction.