非创伤性股骨头坏死体积与坏死指数及角度相关性分析

目的探讨股骨头坏死体积与坏死指数及角度的相关性。方法对39例股骨头坏死患者全髋关节置换术后的51个股骨头，按时钟刻度过头颈结合处将股骨头划分为12等份，平均每份角度为30°。过股骨头球心及1～12点测量每份股骨头坏死角度，排水法测量每份股骨头坏死体积比。对股骨头标本进行二维CT重建，在二维CT重建图像和X线影像中测量坏死角度，并计算得出相应坏死指数。结果12～1点股骨头坏死体积比为（74．5±7．4）％，与过1点平面坏死角度（41．9°±8．3°）呈正相关（r=0．843），1～2点股骨头坏死体积比为（73．7±0．4）％，与过2点平面坏死角度（41．9°±1．8°）呈正相关（r=0．543），11-12点股骨头坏死体积比为（83．6±8．6）％，与过12点平面坏死角度（44．9°±3．9°）呈正相关（r=0．701），且差异有统计学意义（P〈0．01）；股骨头总坏死体积比与过1点平面的坏死角度、改良的坏死指数、坏死指数及Kerboul结合角呈正相关（r=0．798，0．701，0．377，0．398，均P〈0．01）。结论股骨头坏死体积与坏死指数及坏死角度呈正相关，经过股骨头大转子前30°平面坏死角度能较好的反映股骨头坏死体积。

Relationship between volume, angle and extent index in non-traumatic avascular osteonecrosis on the femoral head

Objective To explore the relationship between the osteonecrotic volume (lesion size), angle and the index of necrotic extent on the femoral head. Methods Fifty-one hips in 39 patients with non-traumatic avascular osteonecrosis on the femoral head were divided into 12 equal segments from the head to the neck junction (a turning point of the spherical curve of the head) with whole hip displacement, each with 30 degrees on a coronal plane of weight-bearing surface. The osteonecrotic angle of the arc of each necrotic segment from the center of the femoral head was measured at the point of one- to 12-o'clock on imaging of two dimensional reconstruction of computerized tomography (CT) scans and anteroposterior and lateral radiographs. Necrotic volume on each segment of the femoral head was calculated with fluid displacement method. The index of osteonecrotic extent on the femoral head was calculated using direct anatomical measurements. Results Osteoneerotic volume on the femoral head at the point of 12- to one-o'clock on coronal plane was (74. 5 ± 7.4)% of the sphere equivalent of the whole femoral head, which was positively correlated to its necrotic angle [ (41.9±8. 3) degrees] at the point of one-o'clock on the plane, with a coefficient of correlation of 0. 843, and that at the point of one- to two-o'clock on the plane was (73.7 ±0. 4) %, which was positively correlated to its necrotic angle [ (41.9 ± 1.8) degrees] at the point of two-o'clock, with a coefficient of correlation of 0. 543. Osteonecrotic volume on the point of 11- to 12-o'cleck was (83.6±8.6)%, and the necrotic angle at the point of 12-o'clock was (44. 9±3.9) degrees, which were positively correlated each other, with a coefficient of correlation of 0. 701 (P <0. 01 ). Osteonecrotic volume on the femoral head was positively correlated to its necrotic angle , modified index of necrotic extent, index of necrotic extent and Kerboul conjugated necrotic angle, with coefficients of correlation of 0. 798, 0. 701, 0. 377 and 0. 398 ( P < 0. 01 ), respectively, at the point of one o' clock. Conclusions Measurements of osteonecrotic volume was positively correlated to the index of necrotic extent and necrotic angle on the femoral head, respectively. Necrotic angle on the plane at 30-degree of the trochanter on the femoral head can well reflect its necrotic volume.