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Osteonecrosis of the Human Skeleton
Orthop Clin N Am 35 (2004) xiii – xv
Preface
Osteonecrosis of the Human Skeleton
Panayotis N. Soucacos, MD James R. Urbaniak, MD Guest Editors
Osteonecrosis, also known as avascular necrosis and aseptic necrosis, is a particularly devastating degenerative condition of the human skeleton because of its propensity to strike young adults and its often unrelenting progression despite treatment. Osteonecrosis most commonly affects the femoral head, although it can be found in many parts of the human skeleton. Although the disease is becoming more prevalent, and various inciting factors have been recognized, the pathogenesis remains unclear, and recommended forms of treatment are controversial. The pathogenesis of osteonecrosis remains unknown despite numerous studies. Various hypotheses have been suggested concerning the pathophysiologic mechanisms underlying the disease, including fat embolism, intravascular coagulation, and intraosseous stress. These theories are for the most part not mutually exclusive; rather, they may be mutually supportive in many cases. Moutsopoulos and colleagues address the role of immunologic factors in the pathogenesis of osteonecrosis. The authors suggest that in autoimmune disorders small vessel vasculitis or other disease-associated features, as well as antiphospholipid antibodies, may be involved in the development of osteonecrosis. A relatively high frequency of coagulation abnormalities in patients with hip osteonecrosis was observed by Korompilias and coauthors, who suggest that these abnormalities might increase the risk of bone necrosis by predisposing the patient to throm-
boembolic phenomena. By testing patients with osteonecrotic lesions for haemostatic abnormalities, they attempt to define associations between hypercoagulability and osteonecrosis of the hip. It generally is agreed that successful treatment of patients with osteonecrosis is directly related to the stage of disease at diagnosis. This understanding emphasizes the importance of a reliable classification system. The various classification systems for osteonecrosis currently in use often lead to confusion. Steinberg and colleagues provide an overview of the systems most commonly used today. The authors also outline essential features of an ideal system to enable the reader to decide which of the available classification systems best meets these goals. Changes that occur in blood flow through bone have important implications in disease, and several attempts have been made to correlate vascular patterns with the clinical incidence of osteonecrosis. Johnson and coauthors examine the arterial anatomy of bones that undergo osteonecrosis and assess the type of vascular interruptions that place particular bones. Pape and coworkers address the difficulties in diagnosing early-stage osteonecrosis of the knee. The authors note MRI criteria on T2-weighted images that allow differentiation between transient epiphyseal lesions and early irreversible osteonecrosis of the knee. In cases with suspected secondary osteonecrosis, MRI and bone scintigraphy seem to be valuable tools for establishing a diagnosis.
0030-5898/04/$ – see front matter D 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.ocl.2004.04.003
xiv
P.N. Soucacos, J.R. Urbaniak / Orthop Clin N Am 35 (2004) xiii–xv
By presenting a detailed evaluation of graft – host bone interactions after failed vascularized fibular grafting of femoral head necrosis, Malizos and colleagues attempt to elucidate the reasons of failure of the procedure. The authors report that a vascularized fibula implanted into the femoral head before collapse has the potential for restructuring the major segment of the affected head, delaying joint degeneration for many years if circumferential graft – host union is established. On the contrary, asymmetric bone healing and non-union with the necrotic subchondral bone in the weight-bearing area leads to failure, progression of symptoms, and subsequent early hip replacement. Major and coauthors address the pathologic conditions that can mimic osteonecrosis. The authors comment that MRI has become increasing helpful in establishing an early diagnosis of avascular necrosis. Although avascular necrosis often demonstrates a classic pattern on MRI, findings earlier in the course of the disease are less specific. Bone marrow edema is a common finding on MRI of patients with knee joint pain. Hoffman and colleagues describe the typical MRI signal patterns for bone marrow edema. Because these patterns can be also found with several other diseases, the authors provide key points for the differential diagnosis. They separate bone marrow edema into three distinct etiologic groups and present a short overview of the therapeutic concepts for each group. Femoral neck fractures are frequently complicated by non-union and femoral head osteonecrosis resulting in a difficult clinical situation, particularly for young patients. Existing treatment options include valgus osteotomy to address the biomechanical factors and bone grafting to address the biologic factor. Beris and coauthors propose promising a new operative technique that combines subtrochanteric valgus osteotomy and free vascularized fibular grafting. Osteotomies of the femur and acetabulum have been recommended as a means to unload the necrotic segment of the femoral head and redirect weight bearing through a more viable area. This option is not satisfactory for patients with significant areas of osteonecrosis in the femoral head. Langlais and coworkers report that rotation osteotomy may provide favorable outcomes lasting at least 10 years in a limited number of patients. The authors indicate that the procedure should be considered before flattening of the head occurs and only in patients with a small necrotic volume. Vascularized grafts decompress the femoral head. Decompression is thought to interrupt the cycle of ischemia and interosseous hypertension that may
contribute to the disease. Removing the necrotic bone removes an obstacle for revascularization, and the area is filled with osteoinductive cancellous graft and viable cortical strut to support the subchondral surface. These findings have been supported largely by the excellent results obtained with the free fibular vascularized graft. Urbaniak and colleagues have remained leaders in the field of osteonecrosis during the course of its study. They address the difficult issue of managing osteonecrosis in the patients with systemic lupus erythematosus. The prevalence of osteonecrosis in patients with systemic lupus erythematosus ranges from 14% to 40% and may be related to the dose of steroids used in the patients’ management. Although retention of the femoral head is accepted as the goal of early treatment, methods for treating osteonecrosis of the femoral head remain controversial. Once end-stage osteonecrosis with collapse of the femoral head has developed, total hip arthroplasty has become the accepted means for surgical management of pain and restoration of function. Although the surgical options for patients with late osteonecrosis are limited, the inherent characteristics of the patient with advanced disease (eg, age, activity level, underlying disease, poor bone quality) present a difficult challenge to the surgeon and result in a significant risk for failure. Total hip replacement initially showed relatively poor results when performed in hips with advanced stages of osteonecrosis. Babis and coauthors review the available techniques and implants that have remarkably improved results. Lotke and colleagues describe spontaneous osteonecrosis of the medial tibial plateau, an entity which is less recognized than osteonecrosis of the medial femoral condyle but which presents in a similar manner. These patients present with a sudden onset of pain on the medial side of the knee. The condition is associated with a spectrum of MRI changes in the tibial subchondral bone. On the other hand, Soucacos and colleagues describe generalized osteonecrosis of the knee, including, in addition to osteonecrosis of the medial femoral condyle, which occurs most frequently, osteonecrosis of the patella or the tibial plateau, which compose the osteonecrotic triad of the knee. Although the clinical picture of idiopathic osteonecrosis of the medial femoral condyle seems similar to several other disorders, certain distinct features, including its typical location, clinical symptoms, and late onset of cartilaginous erosion, facilitate differential diagnosis. Despite the progress made in the diagnosis and treatment of idiopathic osteonecrosis of the medial femoral condyle, the prognosis remains severe.
P.N. Soucacos, J.R. Urbaniak / Orthop Clin N Am 35 (2004) xiii–xv
Avascular necrosis of the talus has always been a surgical challenge because the talus is hidden by its anatomic location and has a precarious blood supply. Adelaar and coworkers describe traumatically induced talar avascular necrosis in association with talar body and talar neck fractures. This condition presents a significant problem, because collapse of the talar dome can lead to degenerative changes and pain and disability of the ankle and subtalar joints. Sotereanos and colleagues describe the relatively uncommon entity osteonecrosis of the humeral head. The causative factors underlying osteonecrosis of the humeral head seem to be multifactorial. Although clinical symptoms and cause play a critical role in the treatment of each patient, the authors indicate that staging is the most objective criterion in determining the most appropriate treatment. In this issue, 16 international experts present upto-date studies and new developments in the diagnosis and treatment of osteonecrosis of the human skeleton. The authors cover virtually every aspect of
xv
osteonecrosis including etiology, pathology, diagnosis, imaging, classification, and treatment. A special word of gratitude goes to the authors for sharing their expertise and experience on this insidious and devastating disease, with the hope of eventually untangling the issues related to its diagnosis and treatment. Once again, we would like to express our sincere appreciation to the Editorial Board of Clinics of North America for supporting this effort. Panayotis N. Soucacos, MD University of Athens Medical School, KAT Hospital 2 Nikis Street, Kafissia 14561 Athens, Greece E-mail address: [email protected] James R. Urbaniak, MD Duke University Medical Center 1000 Trent Drive Durham, NC 22710, USA E-mail address: [email protected]
Preface
Osteonecrosis of the Human Skeleton
Panayotis N. Soucacos, MD James R. Urbaniak, MD Guest Editors
Osteonecrosis, also known as avascular necrosis and aseptic necrosis, is a particularly devastating degenerative condition of the human skeleton because of its propensity to strike young adults and its often unrelenting progression despite treatment. Osteonecrosis most commonly affects the femoral head, although it can be found in many parts of the human skeleton. Although the disease is becoming more prevalent, and various inciting factors have been recognized, the pathogenesis remains unclear, and recommended forms of treatment are controversial. The pathogenesis of osteonecrosis remains unknown despite numerous studies. Various hypotheses have been suggested concerning the pathophysiologic mechanisms underlying the disease, including fat embolism, intravascular coagulation, and intraosseous stress. These theories are for the most part not mutually exclusive; rather, they may be mutually supportive in many cases. Moutsopoulos and colleagues address the role of immunologic factors in the pathogenesis of osteonecrosis. The authors suggest that in autoimmune disorders small vessel vasculitis or other disease-associated features, as well as antiphospholipid antibodies, may be involved in the development of osteonecrosis. A relatively high frequency of coagulation abnormalities in patients with hip osteonecrosis was observed by Korompilias and coauthors, who suggest that these abnormalities might increase the risk of bone necrosis by predisposing the patient to throm-
boembolic phenomena. By testing patients with osteonecrotic lesions for haemostatic abnormalities, they attempt to define associations between hypercoagulability and osteonecrosis of the hip. It generally is agreed that successful treatment of patients with osteonecrosis is directly related to the stage of disease at diagnosis. This understanding emphasizes the importance of a reliable classification system. The various classification systems for osteonecrosis currently in use often lead to confusion. Steinberg and colleagues provide an overview of the systems most commonly used today. The authors also outline essential features of an ideal system to enable the reader to decide which of the available classification systems best meets these goals. Changes that occur in blood flow through bone have important implications in disease, and several attempts have been made to correlate vascular patterns with the clinical incidence of osteonecrosis. Johnson and coauthors examine the arterial anatomy of bones that undergo osteonecrosis and assess the type of vascular interruptions that place particular bones. Pape and coworkers address the difficulties in diagnosing early-stage osteonecrosis of the knee. The authors note MRI criteria on T2-weighted images that allow differentiation between transient epiphyseal lesions and early irreversible osteonecrosis of the knee. In cases with suspected secondary osteonecrosis, MRI and bone scintigraphy seem to be valuable tools for establishing a diagnosis.
0030-5898/04/$ – see front matter D 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.ocl.2004.04.003
xiv
P.N. Soucacos, J.R. Urbaniak / Orthop Clin N Am 35 (2004) xiii–xv
By presenting a detailed evaluation of graft – host bone interactions after failed vascularized fibular grafting of femoral head necrosis, Malizos and colleagues attempt to elucidate the reasons of failure of the procedure. The authors report that a vascularized fibula implanted into the femoral head before collapse has the potential for restructuring the major segment of the affected head, delaying joint degeneration for many years if circumferential graft – host union is established. On the contrary, asymmetric bone healing and non-union with the necrotic subchondral bone in the weight-bearing area leads to failure, progression of symptoms, and subsequent early hip replacement. Major and coauthors address the pathologic conditions that can mimic osteonecrosis. The authors comment that MRI has become increasing helpful in establishing an early diagnosis of avascular necrosis. Although avascular necrosis often demonstrates a classic pattern on MRI, findings earlier in the course of the disease are less specific. Bone marrow edema is a common finding on MRI of patients with knee joint pain. Hoffman and colleagues describe the typical MRI signal patterns for bone marrow edema. Because these patterns can be also found with several other diseases, the authors provide key points for the differential diagnosis. They separate bone marrow edema into three distinct etiologic groups and present a short overview of the therapeutic concepts for each group. Femoral neck fractures are frequently complicated by non-union and femoral head osteonecrosis resulting in a difficult clinical situation, particularly for young patients. Existing treatment options include valgus osteotomy to address the biomechanical factors and bone grafting to address the biologic factor. Beris and coauthors propose promising a new operative technique that combines subtrochanteric valgus osteotomy and free vascularized fibular grafting. Osteotomies of the femur and acetabulum have been recommended as a means to unload the necrotic segment of the femoral head and redirect weight bearing through a more viable area. This option is not satisfactory for patients with significant areas of osteonecrosis in the femoral head. Langlais and coworkers report that rotation osteotomy may provide favorable outcomes lasting at least 10 years in a limited number of patients. The authors indicate that the procedure should be considered before flattening of the head occurs and only in patients with a small necrotic volume. Vascularized grafts decompress the femoral head. Decompression is thought to interrupt the cycle of ischemia and interosseous hypertension that may
contribute to the disease. Removing the necrotic bone removes an obstacle for revascularization, and the area is filled with osteoinductive cancellous graft and viable cortical strut to support the subchondral surface. These findings have been supported largely by the excellent results obtained with the free fibular vascularized graft. Urbaniak and colleagues have remained leaders in the field of osteonecrosis during the course of its study. They address the difficult issue of managing osteonecrosis in the patients with systemic lupus erythematosus. The prevalence of osteonecrosis in patients with systemic lupus erythematosus ranges from 14% to 40% and may be related to the dose of steroids used in the patients’ management. Although retention of the femoral head is accepted as the goal of early treatment, methods for treating osteonecrosis of the femoral head remain controversial. Once end-stage osteonecrosis with collapse of the femoral head has developed, total hip arthroplasty has become the accepted means for surgical management of pain and restoration of function. Although the surgical options for patients with late osteonecrosis are limited, the inherent characteristics of the patient with advanced disease (eg, age, activity level, underlying disease, poor bone quality) present a difficult challenge to the surgeon and result in a significant risk for failure. Total hip replacement initially showed relatively poor results when performed in hips with advanced stages of osteonecrosis. Babis and coauthors review the available techniques and implants that have remarkably improved results. Lotke and colleagues describe spontaneous osteonecrosis of the medial tibial plateau, an entity which is less recognized than osteonecrosis of the medial femoral condyle but which presents in a similar manner. These patients present with a sudden onset of pain on the medial side of the knee. The condition is associated with a spectrum of MRI changes in the tibial subchondral bone. On the other hand, Soucacos and colleagues describe generalized osteonecrosis of the knee, including, in addition to osteonecrosis of the medial femoral condyle, which occurs most frequently, osteonecrosis of the patella or the tibial plateau, which compose the osteonecrotic triad of the knee. Although the clinical picture of idiopathic osteonecrosis of the medial femoral condyle seems similar to several other disorders, certain distinct features, including its typical location, clinical symptoms, and late onset of cartilaginous erosion, facilitate differential diagnosis. Despite the progress made in the diagnosis and treatment of idiopathic osteonecrosis of the medial femoral condyle, the prognosis remains severe.
P.N. Soucacos, J.R. Urbaniak / Orthop Clin N Am 35 (2004) xiii–xv
Avascular necrosis of the talus has always been a surgical challenge because the talus is hidden by its anatomic location and has a precarious blood supply. Adelaar and coworkers describe traumatically induced talar avascular necrosis in association with talar body and talar neck fractures. This condition presents a significant problem, because collapse of the talar dome can lead to degenerative changes and pain and disability of the ankle and subtalar joints. Sotereanos and colleagues describe the relatively uncommon entity osteonecrosis of the humeral head. The causative factors underlying osteonecrosis of the humeral head seem to be multifactorial. Although clinical symptoms and cause play a critical role in the treatment of each patient, the authors indicate that staging is the most objective criterion in determining the most appropriate treatment. In this issue, 16 international experts present upto-date studies and new developments in the diagnosis and treatment of osteonecrosis of the human skeleton. The authors cover virtually every aspect of
xv
osteonecrosis including etiology, pathology, diagnosis, imaging, classification, and treatment. A special word of gratitude goes to the authors for sharing their expertise and experience on this insidious and devastating disease, with the hope of eventually untangling the issues related to its diagnosis and treatment. Once again, we would like to express our sincere appreciation to the Editorial Board of Clinics of North America for supporting this effort. Panayotis N. Soucacos, MD University of Athens Medical School, KAT Hospital 2 Nikis Street, Kafissia 14561 Athens, Greece E-mail address: [email protected] James R. Urbaniak, MD Duke University Medical Center 1000 Trent Drive Durham, NC 22710, USA E-mail address: [email protected]