SLR - December 2016 - Chandana Halaharvi

Talar Osteonecrosis Related to Adult Sickle Cell Disease: Natural Evolution from Early to Late Stages

Reference:
Hernigou P, Flouzat-Lachaniette CH, Daltro G, Galacteros F. Talar Osteonecrosis Related to Adult Sickle Cell Disease: Natural Evolution from Early to Late Stages. J Bone Joint Surg Am. 2016 Jul 6; 98 (13): 1113–1121

Scientific Literature Review


Reviewed By: Chandana Halaharvi, DPM
Residency Program: Grant Medical Center

Podiatric Relevance: Osteonecrosis of the talus in patients with sickle cell disease is rare. There is a paucity in the literature describing the progression of talar osteonecrosis in patients with sickle cell disease. Consequently, the literature describing surgical treatment of osteonecrosis of the talus is limited. Options include core decompression, vascularized rotational bone grafts, arthrodesis and arthroplasty. The authors sought to define the progression of talar osteonecrosis in the asymptomatic and symptomatic patients starting at the early stages in sickle cell disease by asking two main questions. First, to identify the delay between the diagnoses of talar osteonecrosis with the collapse of the talus and second, to recognize the influential factors in the patient that results in the talar collapse.

Methods: Forty-five patients with sickle cell disease (20 men, 25 women with mean age of 28 years) were confirmed with radiographs the diagnosis of early talar osteonecrosis between 1985 and 1995 with an average follow-up of 20 years. Osteonecrosis was identified in 75 tali, unilateral in 15 patients and bilateral in 30 patients at the initial examination. There were four cases with associated distal tibial osteonecrosis of the ankle. Osteonecrosis of the talus was observed in seven patients homozygous for hemoglobin S (S/S genotype), 26 with hemoglobin S/hemoglobin C and 12 patients with hemoglobin S/beta-thalassemia. All 45 patients were followed up clinically and radiographically every six months until talar collapse or surgical intervention and then once a year until 2010. The authors categorized the talar osteonecrosis into five stages using radiographs and MRI according to the modified Ficat and Arlet classification system.

Results: At initial evaluation, 45 ankles were asymptomatic, and 32 were identified at stage I, of which 25 became symptomatic and 13 were stage II, all of which progressed to being symptomatic. The average interval between the collapse and surgery in the asymptomatic population was nine years. There were 30 ankles that presented as symptomatic initially, 10 were defined at stage I and 20 as stage II. All 30 ankles that were symptomatic progressed to talar collapse within five years. The best indicator of the progression of the disease in an asymptomatic talus was the stage of osteonecrosis at diagnosis. Risk factors for progression of the disease were associated with certain genotypes, extent and location of lesions, pain and stage at presentation. Fusion was obtained in 48 of the 54 ankles; however, 32 ankles required more than one procedure to obtain fusion.

Conclusion: The authors evaluated the rate of progression of talar osteonecrosis through radiographs as well as addressing the clinical evolution of the symptomatic and asymptomatic patients with this disease in the presence of sickle cell disease. They were able to identify certain risk factors that lead to rapid progression of the disease and talar collapse. Interestingly, the authors recognized that an isolated talar osteonecrosis is extremely rare without associated osteonecrosis in the hip or elsewhere in the adult sickle cell population. They recommend patients with talar osteonecrosis related to sickle cell to obtain bilateral hip MRI at the time of diagnosis along with considering the surgical option to avoid collapse of a symptomatic talus. Talar collapse can occur quickly after onset of pain, hence, symptomatic osteonecrosis of the talus is expected to show clinical and radiographic evidence of progression over time. 

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