[Comparison between pathology and computer for quantitative determination of femoral head necrosis]

To compare computer measurement semi automatic quantitative detection software system with ultra thin layer pathological section to confirm the avascular necrosis percentage of the femoral head, and provide reference for clinical treatment options.

From June 2012 to December 2013, the X-ray and MRI of 24 patients(24 hips on unilateral) were reviewed, who had avascular necrosis of the femoral head at late stage (stage III and IV) according to the ARCO international staging system, and performed by total hip arthroplasty. There were 15 males and 9 females, with an average age of (65.1±8.8) years old ranging 33 to 74 years old. Based on imaging system combined with computer aided technology(CAD) system and postoperative ultrathin slice, the volume of the area of femoral head necrosis were calculated. Then combining with the total volume of the femoral head was calculated by X-ray, the percentage of each femoral head necrosis area was calculated as a percentage of the whole ball head in both methods.

For 24 hips, the normal femoral head volume was (39.58±3.29) cm³ on average of X-ray film, the necrotic volume was (20.00±3.04) cm³ on average of MRI by the calculation of computer. The necrotic volume occupying in the volume of the normal femoral head was (42.92±6.09)% on average ranged. The necrotic lesion size was larger than 40% in 16 hips, 30% to 40% in 8 hips, 1 ess than 30% in 0 hip. Under the pathological section, the necrosis volume was (19.89±3.17) cm³, the necrotic volume occupying in the volume of the normal femoral head was (40.33±6.36)%. The necrotic lesion size was larger than 40% in 12 hips, 30% to 40% in 11 hips, 1 ess than 30% in 1 hip. In computer and general measurement, the two entire femoral head volume difference was (0.113±0.466) cm³, there was no significant difference using these measurements(t=-1.186, P=0.248). After the linear correlation statistics analysis, there was a positive correlation relationship in necrotic volume between computer software and pathology measurement(γ=0.980, P=0.000).

The severity of the necrotic femoral head is closely related to the percentage of necrotic area. When the ratio of necrotic lesions and the whole femoral head is greater than 30%, the patients' clinical symptoms tend to aggravate, the probability of total hip arthroplasty increased significantly. It have great significances in femoral head necrosis installment, judge the prognosis, guide the selection of treatment and monitoring curative effect.