急性髌骨外侧脱位的MRI分析

MR Features of Acute Lateral Patellar Dislocation

目的结合损伤机制探讨急性髌骨外侧脱位的MRI特征表现。资料与方法回顾性分析42例急性髌骨外侧脱位患者的MRI资料,由两名放射科医师共同确定骨髓水肿、骨软骨骨折、髌骨位置、髌骨内侧支持带的损伤、关节积液及其他合并损伤情况。结果(1)股骨外髁前侧面和髌骨内下关节面骨髓水肿的出现率均为98%(41/42),其中95%(40/42)两处同时出现。其余区域骨髓水肿的出现率仅为7%(3/42)。(2)36%(15/42)可见髌骨内后缘骨软骨骨折,10%(4/42)出现股骨外髁骨软骨骨折,其余区域则无。(3)2%(1/42)髌骨仍处于脱位状态,50%(21/42)髌骨呈半脱位,其余48%(20/42)髌骨位置正常。(4)62%(26/42)可见髌骨内侧支持带异常,43%(18/42)合并股内侧斜肌损伤,37%(16/42)合并股外侧肌水肿,7%(3/42)出现髌骨外侧支持带异常,2%(1/42)合并内侧副韧带损伤。(5)100%(42/42)出现关节积液,包括关节积血5例、关节脂血症2例。结论急性髌骨外侧脱位的MRI表现取决于其特定的损伤机制,股骨外髁前侧面和髌骨内下关节面同时出现的骨髓水肿、髌骨内后缘的骨软骨骨折、髌骨内侧支持带异常、股内侧斜肌和股外侧肌的损伤为常见而又具有特征的MRI征象。

Objective To describe MRI findings of acute lateral patellar dislocation.Materials and Methods MRI images of 42 cases with acute lateral patellar dislocation were retrospectively evaluated by 2 radiologists with consensus.The incidence of the bone marrow edema,osteochondral fracture,abnormality of patella position,disruption of the medial retinaculum and medial patellofemoral ligament,joint effusion,and other associated injuries were recorded.Results（1） The incidences of bone marrow edema occurred on the anterolateral aspect of the lateral femoral condyle and the medial facet of the patella were the same 98%（41 of 42）,among them,95%（40 of 42）of lesions occurred on both sites.Bone marrow edema in other site was only present in 7%（3 of 42）.（2） Osteochondral fractures recorded in medial facet of the patella were 36%（15 of 42） and in lateral femoral condyle 10%（4 of 42）.（3） Patella dislocation was identified in 1 case（2%）and lateral subluxation was seen in 21cases（50%）.Nearly normal patella position was found in other 20 cases（48%）.（4） 62%（26 of 42）of cases showed disruption of the medial retinaculum,involved vastus medialis obliquus in 18 cases（43%）,vastus lateralis in 16 cases（37%）,lateral patellar retinaculum in 13 cases（7%） and medial collateral ligament in 1 case（2%） respectively.（5） 100%（42 of 42）of cases showed joint effusion,including hemarthrosis in 6 cases and lipohemarthrosis in 2 cases.Conclusion Medial patellar and lateral femoral bone contusion,osteochondral fragments of the medial patellar facet,medial retinaculum disruption,injuries of the vastus medialis obliquus and the vastus lateralis were the characteristics of acute lateral patellar dislocation.