桡骨远端骨折致月骨损伤的MRI表现

MR imaging of the lunate injuries secondary to the distal radius fractures

目的通过分析桡骨远端骨折合并腕骨损伤的MRI表现,证明桡骨撞击可以导致月骨损伤。方法自1997年3月至6月收治急症初诊桡骨远端骨折患者46例,男16,女30例;年龄28～62岁,平均48.2岁。确诊后均采取保守治疗,复位纠正阳性尺骨变异,尺骨变异范围要求达到1.5mm以内。骨折按MayoClinic分型：Ⅰ型18例（39%）、Ⅱ型14例（30%）、Ⅲ型9例（20%）、Ⅳ型5例（11%）。拍摄腕部正位及侧位X线片,用投影线技术测量尺骨变异。行CT检查排除月骨和三角骨微骨折、囊性变和先天发育不良。行MR检查观察月骨损伤和损伤信号出现的位置。结果MRI出现月骨损伤信号42例（91%）,Ⅰ型15例（15/18,83%）、Ⅱ型13例（13/14,93%）、Ⅲ型9例（9/9,100%）、Ⅳ型5例（5/5,100%）。损伤信号单纯位于月骨尺侧近端35例（占月骨损伤信号的83%）,单纯位于月骨中部5例（12%）,月骨中部和尺侧近端同时出现损伤信号2例（5%）。月骨中部出现损伤信号的7例患者中5例为MayoClinicⅢ型桡骨远端骨折,MayoClinic骨折类型与月骨中部损伤信号的出现率有相关性（Χ^2=19.475,P=0.000,r=0.545）。三角骨中心出现损伤信号2例,与月骨相关节的桡骨区出现不同程度的损伤信号。结论桡骨远端骨折导致的月骨损伤,其MRI上月骨损伤信号位于不同部位,从力学角度分析月骨中部的损伤信号应为桡骨撞击所致。

Objective To analysis MR imaging features of distal radius fracture associating with wrist bones injuries, and try to demonstrate that radius impingement can lead to lunate injury. Methods 46 patients with acute distal radius fracture from March 1997 to June 1997 were involved in this study, including 16 males, 30 females, with the mean age of 48.2 years （ranged 28-62 years）. According to Mayo Clinic classification, there were type Ⅰ 18 cases （39%）; type Ⅱ 14 cases （30%）; type Ⅲ 9 cases （20%）, type Ⅳ 5 eases （11%）. All patients were treated with close reduction, and correcting positive ulnar variance limiting to 1.5 mm. Standardized posteroanterior and lateral radiographic images were obtained pre- and post-reduction. No micro-fracture of lunate and triquetrum, lunate eystoid and congenital dysplasia were found during CT scan. Using MR imaging to diagnose lunate injury and confirm the location of abnormal signal. Results MR imaging examination found 42 cases （91% of the distal radius fratures） with the lunate injuries, including 15 cases in Mayo Clinic type Ⅰ fractures （83%）, 13 cases in type Ⅱ （93%） , 9 cases in type Ⅲ（100%） , and 5 cases in typeⅣ（100%）. The abnormal signal of lunate injury was found only at the ulnar side of proximal lunate in 35 cases （83%）, only at the middle of lunate in 5 cases （12%）, at the ulnar side and middle of lunate in 2 cases （5%）. In the 7 lunate middle injuries, 5 cases were Mayo Clinic type Ⅲ fractures. There was significant correlation between Mayo Clinic classification system and lunate injury （Χ^2=19.475, P=0.000, r= 0.545）. Conclusion The fractures of distal radius can result in lunate injury. The MRI signals of lunate injury locate at different places, and radius impingement can cause MRI injury signal at middle lunate depending on mechanical analysing.