SLR - October 2016 - Jeffrey Demian

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):1113–21.

Scientific Literature Review

Reviewed By: Jeffrey Demian, DPM
Residency Program: Chino Valley Medical Center, Chino, California

Podiatric Relevance: Sickle cell disease has been shown to be associated with femoral head osteonecrosis but also has a predilection in affecting the talus. In many instances, when the patient presents for the condition, it is generally at the stage in which surgical intervention is required. Conservatively, pain control is attempted with limitation of weightbearing and motion to the ankle joint, whereas surgical intervention consists of core decompression to areas of necrosis with grafting and, in later stages, fusion, which is difficult to obtain in a joint with osteonecrosis. Knowing the natural history of talar osteonecoris can help to better plan treatment regimens especially for younger patients with long life expectancies. The study was performed to define the natural progression of asymptomatic and symptomatic talar osteonecrosis from its early stages in patients with sickle cell disease.

The paper will address the clinical question of what the delay is between the diagnosis of talar osteonecrosis and collapse of the talus, along with the affects of the sickle cell genotypes, pain at presentation, collapse of the contralateral talus, stage of osteonecrosis at diagnosis and the extent of the osteonecrosis affecting talar collapse.

Methods: This is a prospective study out of the sickle cell disease center. Forty-five patients with early stage talar osteonecrosis in 75 tali [femoral head AVN classification (FICAT ARLET) 1 or 2] were identified, using radiographic and magnetic resonance imaging, in which 45 were asymptomatic cases and 30 symptomatic at initial evaluation. Seven patients were homozygous for hemoglobin S, 26 were heterozygous for hemoglobin S/C and 12 were heterozygous for hemoglobin S/beta-thalassemia. Patients had clinical and radiographic follow-up every six months until talar collapse or surgical intervention. The clinical progression, clinical progression defined as the need for surgery, radiographic progression and disease progression until collapse occurred were calculated. The variables explored were volume of osteonecrosis, location of the lesion, stage of osteonecrosis, genotype of sickle cell disease and collapse of the contralateral talus.

Results: Of the 45 asymptomatic tali, 25/32 that were stage 1 became symptomatic, and 13/13 that were stage 2 became symptomatic within eight years. Mean interval between diagnosis and first symptoms was five years for the stage 1 and less than eight years for the stage 2. Thirty-five of the 38 tali that became symptomatic went on to collapse, which was preceded by pain. 29/45 asymptomatic tali deteriorated to the point that surgery was required. Of the 30 symptomatic tali, 10/30 were stage 1 and 20/30 were stage 2 with all 30 collapsing with mean time between diagnosis and collapse being five years for stage 1 and three years for stage 2. 25/30 tali deteriorated to the point that surgery was required with mean interval between collapse and surgery being six years.

Conclusions: The stage of talar osteonecrosis at diagnosis is the best predictor for clinical progression of the disease with stage 1 and 2 collapsing within three to five years. Pain with presentation was a predictor of radiographic progression of the disease, in which collapse may occur quickly after the onset of pain. Patients who had talar collapse on the contralateral limb had a greater risk for the talus collapsing within two years. The S/S genotype was at a significantly higher risk factor for rapid progression of the disease and collapse, compared to other genotypes. The location and extent of lesion with regards to the articular surface were predictors of radiographic evolution where middle and posterior lesions have higher rates of collapse.  

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