Ferri Melanie, Scharfenberger Angela V, Goplen Gord, Daniels Timothy R, Pearce Dawn
Foot Ankle Int. 2008 Feb;29(2):199-204. doi: 10.3113/FAI.2008.0199.
The three-dimensional relationships of the bones in the foot in a flatfoot deformity are difficult to assess with standard radiographs. CT scans demonstrate these relationships but are typically made in a nonweightbearing mode. Our objective was to assess the use of a weightbearing CT apparatus to image the feet in patients with severe flexible pes planus deformities and to better define the anatomical changes that occur.
A specialized device was designed and constructed to simulate weightbearing to the feet during CT examination. Eighteen normal feet and 30 painful severe and flexible pes planus feet were imaged in both the non weightbearing and weightbearing states, set at 50% of body weight. Several measurements of intertarsal relationships were made of the pes planus and normal feet. Navicular floor to skin distance, forefoot arch angle, and subtalar joint subluxation were measured in the coronal plane in both the weightbearing and nonweightbearing states. T-tests were used to analyze measurements of navicular floor to skin distance and forefoot arch angle.
The weightbearing device had a significant effect on foot configuration for both normal and pes planus feet (p = 0.0008) and (p < 0.0001) respectively for both floor to skin distance and forefoot arch angle. There was a significant difference between normal feet and pes planus feet with regard to the forefoot arch angle in the nonweightbearing (p = 0.02) and weightbearing states (p = 0.01). Four of the pes planus patients had evidence of subtalar joint subluxation which was more pronounced in the weightbearing state. There was no significant difference between the navicular floor to skin distance in the normal versus pes planus feet in either the non weightbearing (p = 0.05) or the weightbearing states (p = 0.07).
A device was designed and constructed to apply a weightbearing load equal to that of 50% body weight with minimal to no patient discomfort. The resultant effects on foot configuration were significant, and are useful for assessment of degree of flexible flat foot deformity, thus guiding clinical management. The measure which most significantly differed between pes planus patients and normal volunteers was the forefoot arch angle. Forefoot arch angle may therefore be the most useful measure for the imaging diagnosis of flexible pes planus, and the degree of planus deformity.
扁平足畸形时足部骨骼的三维关系难以通过标准X线片进行评估。CT扫描能显示这些关系，但通常是在非负重状态下进行的。我们的目的是评估使用负重CT设备对重度柔韧性扁平足畸形患者的足部进行成像，并更好地明确所发生的解剖学变化。
设计并制造了一种专门的装置，用于在CT检查期间模拟足部负重。对18只正常足和30只疼痛性重度柔韧性扁平足在非负重和负重状态（设定为体重 的50%）下进行成像。对扁平足和正常足的跗骨间关系进行了多项测量。在负重和非负重状态下，在冠状面测量舟骨底面至皮肤的距离、前足弓角度和距下关节半脱位情况。采用t检验分析舟骨底面至皮肤距离和前足弓角度的测量结果。
负重装置对正常足和扁平足的足部形态均有显著影响（分别对底面至皮肤距离和前足弓角度，p = 0.0008和p < 0.0001）。在非负重（p = 0.02）和负重状态（p = 0.01）下，正常足和扁平足的前足弓角度存在显著差异。4例扁平足患者有距下关节半脱位的证据，在负重状态下更为明显。在非负重（p = 0.05）或负重状态（p = 0.07）下，正常足与扁平足的舟骨底面至皮肤距离均无显著差异。
设计并制造了一种装置，可施加相当于体重50%的负重，且患者不适感最小或无不适感。对足部形态产生的结果具有显著意义，有助于评估柔韧性扁平足畸形的程度，从而指导临床治疗。扁平足患者与正常志愿者之间差异最显著的测量指标是前足弓角度。因此，前足弓角度可能是柔韧性扁平足成像诊断及扁平畸形程度最有用的测量指标。
