1、Normal radiographs of the knee with anteroposterior (a),lateral (b),and axial (c) biew demonstrate normal patellar position and morphology. The anteroposterior projection (a) is useful for evaluting the femur and proximal tibia, femoral and tibial plateaus. The lateral projection is useful for evalu
2、ating patellar height,patellofemoral compartment, suprapatellar recess (SR), quadriceps tendon (QT), patellar tendon (PT). The axial view of the patella helps in assessment of the shape of the patella, note media (MF) and lateral (LF) patellar facets and median ridge (MR). Also note normal and rough
3、 anterior patellar cortex (blue arrow).,Fig. 1: Normal knee radiographs 图1：正常膝关节,Sagittal proton density (a) and axial fat-suppressed T2-weighted (b) MR images of a normal knee. Note the low signal patellar (PT) and quadriceps (QT) tendons and the thick, homogeneous-appearing patellar cartillage (re
4、d arrows). Note the lateral and media retinacula, passive stabilizers of the patella.,Fig. 2: Normal MR images 图2：正常膝关节MR图像,In 1941, Wiberg classified patellar shape into three different morphologies: Type I (a) demonstrates roughly symmetric and equal-sized, concave medial (MF) and lateral (LF) pat
5、ellar facets. Type II (b) shows a medial facet that is slightly smaller than the lateral facet and a concave lateral facet. Type III (c) also shows a smaller and more vertically oriented medial patellar facet, which is associated with maltracking disorders 18.,Fig. 3: Variations in patellar morpholo
6、gy 图3：髌骨形态变异,5-year-old male with hereditary osteo-onychodysplasia (nail-patella syndrome). AP (a), later (b), and axial (c) views of the knee demonstrate complete absence of the bilateral patellar ossification centers.,Fig. 4: Patellar aplasia 图4：髌骨发育不良5岁男孩遗传性指(趾)甲-髌骨综合征（nail-patella syndrome）,Ante
7、roposterior and axial radiographs (a) show bilateral, well-corticated ossified fragments in the superolateral aspect of the patellas (arrows). Coronal and axial T2-weighted fat-suppressed MR image (b) show the well-corticated ossified fragment. Note the normal bone marrow signal and cartilage across
8、 the synchondrisis, The well-corticated nature of the fragment and lack of abnormal marrow signal help to differentiate this entity from a patellar fracture.,Fig. 5: Bipartite patella 图5：二分髌骨,Anteroposterior, lateral, and axial radiographs (s) show a lucent, round lesion with well-defined margins at
9、 the superolateral aspect of the patella (arrows). Sagittal proton density and axial T2-weighted fat-suppressed MR images (b) show a focal subchondral osseous defect with intact-appearing overlying cartilage; the cartilage is thickened, and fills the defect. There is normal bone marrow signal and sm
10、ooth, homogeneous signal of the articular cartilage.,Fig. 6: Dorsal defect of the patella 图6：髌骨背侧缺损（DDP）,Congenital patella alta is an anatomic risk factor for patellofemoral instability. The insall-Salvati index is the ratio of the length of the patella (PL) to the patellar tendon (PT). The normal
11、value is between 1.0 and 1.2, with increased values indicating patella alta and decreased value indicating patella baja. Lateral radiograph (a) at approximately 30 degrees of knee flxion shows a noemally placed patella, with Insall-Salvati index of 1.1. Lateral radiograph (b) of an 8-year-old male s
12、hows patella alta, with Insall-Salvati index measuring 1.8. Axial T2-weighted tubro spin echo MR image (c) form this same patient shows finding of a lateral patellar dislocation. There is bone marrow edema of the medial aspect of the patella (arrow) and disruption of the medial patellar retinaculum
13、(asterisk). This patient had a history of recurrent dislocations, likely due to his congenital patella alta.,Fig. 7: Patella alta 图7：高位髌骨a图正常位置髌骨，髌韧带长度（PT）/髌骨长度（PL）正常比值为1.0-1.2（国内文献一般小于0.8提示低位髌骨，大于1.2提示高位髌骨）；b图PT/PL比值为1.8；c图示髌骨脱位状态，局部骨髓水肿。高位髌骨通常无症状，尽管它是膝关节不稳定的重要解剖危险因素之一。,Anteroposterior (a) and late
14、ral (b) radiographs of a 15-year-old female patient with cingenital right-sided patella baja.,Lateral radiographs of a patient one year following total knee arthroplasty demonstrates patella baja. The patellar tendon is scarred to the upper tibia (arrow).,Patella baja may also be seen in association
15、 with neuromuscular diseases. Fromtal (c) and lateral (d) radiographs in this patient with a history of polio show marked patella baja. Also nite that the bine are osteopenic and gracile and that there is a paucity of soft tissues, in keeping with the patients history of polio.,Fig. 8: Patella baja
16、图8：低位髌骨a,b图，15岁女孩右膝先天性低位髌骨。c,d图，低位髌骨也见于神经肌肉疾病；患者既往有脊髓灰质炎病史。e图，人工膝关节置换后患者一年复查，侧位片提示低位髌骨；箭头是髌韧带疤痕形成。,Trochlear dysplasia is among the most significant anstomic factors contributing to patellar maltracking Lateral radiograph (a)depicts one sign,the crossing sign,in which the line of the deepest aspect
17、of the trochlear groove crosses over the antenor aspect of the femoral condyles (arrow).Sagittal proton density image (b) depicts another hnding of trochlear dysplasia.The ventral trochlear prominence (vtp)has been detined as the distance between the line paralleling the ventral cortical surface of
18、the distal femur and the most anterior point of the femoral trochlear floor.In this image is seen a step-like deformity at the intertace of the anterior femoral cortex and trochiea with a vte measuring 9 mm,consistent with trochlear dysplasia.Axial T2- weighted fat-suppressed image (c) shows a conge
19、nitaly dysplastic trochlea with a markedly shallow trochiear depth (arrow),consistent with trochlear dysolbsia Addisanally noted is marked asymmetry of the medial (MF) and lateral (LF) trochlear facets.A lateral to medalfemoral facet.rano ot greater than 1.75 is generally considered diagrosnc for tr
20、ochlear dysplasia.In this case the ratio measures23. representing another tinding of trochlear doplasia,Fig. 9: Trochlear dysplasia 图9：（股骨）滑车发育不良股骨滑车发育不良是指滑车沟前部的几何外形和深度存在的解剖学异常。可引起髌骨轨迹不良或慢性膝关节不稳。,Trochlear depth assessed on axial T2-weighted fat-suppressed images.A line is first drawn parallel to th
21、e posterior temoral condies (A).Lines drawn perpendicular to this indicate the anteroposterior dimensions of the lateral(B) and medial (C) trochlear facets and of the deepest portion of the lemoral trochlea (D)Calculate trochlear depth with the equaion (BC/2)-D.Trochlear depth of 3 mm or less indica
22、tes trochlear dysplasia.image(a) shows a normal trochlear depth,image (b)shows a dysplasnc trochlea with marked flattening,Fig. 10: Trochlear dysplasia measurement of trochlear depth 图10：滑车发育不良-滑车深度的测量计算公式：（B+C/2）-D；小于3mm提示滑车发育不良。a图是正常的滑车深度，b图是滑车发育不良，呈扁平状。,The distance from the tibial tubercle to th
23、e trochilear groove is measured on axial MR images.A distance of 20 mm indicates considerable lateralization and is almost always associated with patellar instability.Axial MR images in the top row(a)show a normal tibial-tubercle groove distance(blue double-headed arrow).Images in the second row (b)
24、show markedly lateral position of the tibial tubercle in relation to the trochlear groove(blue double-headed arrow).,Fig. 11: Lateralization of the tibial tubercle 图11：胫骨结节的偏侧性胫骨结节的偏侧性通过测量胫骨结节-股骨滑车间距离来定性，测量方法：分别选择通过胫骨结节的横断面图像，及通过股骨髁间窝呈“罗马拱门”形态的层面；勾画出胫骨结节的层面，通过软件和股骨髁间窝层面图像融合，在此新的图像上标记股骨后髁的切线作为参考线，然后分
25、别过股骨滑车最低点和胫骨结节中点作股骨后髁切线的垂线，2条垂线的距离即为胫骨结节-股骨滑车间距离。意义：反映施加于膝关节的屈伸装置的外翻矢量。小于15mm正常；15-20毫米临界；大于20mm诊断髌骨不稳。a图是正常，b图提示髌骨不稳。,30-vear old female former long distance runner presents with progressively increasing knee pain for 3 years,now sugnihcantly limiting her actinty Lateral radiograph(a) shows subchon
26、dral sclerosis (blue arrow) of the patela.Sagittal proton density (b),sagittal T2-weighted fat-suppressed (cl,and anial T2- weighted fat-suppressed (d)images show muitifocal areas of full-thickness cartilage fissuring along the patelitlafwhite arrows).with subjacent areas of marrow edema (red arrows
27、)and subcortical cystic change.Note the normal carhlage elsewhere.,Fig. 12:Chondromalacia patellae 图12：髌骨软化症 女，30岁，长跑运动员，进行性膝关节疼痛3年；运动受限就诊。 a图蓝箭示髌骨软骨下骨质硬化；b，c，d图示多发局灶性全层软骨裂隙伴相软骨下骨髓水肿和皮质下囊变。,15-year-old male patient with knee pain.Lateral (a) and axial (b)radiographs show irregularity and a defect al
28、ong the patellar apex(arrows).Sagittal proton density (c)and axial T2-weighted fat-suppressed(d)images show an osteochondral lesion in the mid patella at the apex with bone marrow edema (asterisk). Sagittal proton density image (e)from MRI performed 6 years later shows interval resolution of the les
29、ion.,Fig. 13:Osteochondritis dissecans 图13：剥脱性骨软骨炎 15岁男孩，膝关节痛。a，b图示髌骨下级不规则 缺损；c，d图示局部骨软骨游离伴软骨下骨髓水肿；e图示6年后复查，病灶修复。,13-year-old female presenting with knee pain.Sagittal proton density (a),sagittal fat suppressed proton density(b),and axial fat-saturated proton density(c)MR images show an osteochondri
30、tis dissecans lesion.There is surrounding high signal (black arrows) with small cystic change and focal cartilage defect.Sagittal proton density image (d)from four months later,following arthroscopic lesion repair,shows a well:incorporated bone graft.,Fig. 14: Unstable osteochondritis dissecans lesi
31、on 图14：不稳定的剥脱性骨软骨炎 13岁女孩膝关节疼痛；a，b，c图示髌骨局部骨软骨病灶周围见液体信号影；d图关节镜修复后4个月复查，显示移植骨愈合良好。,16-year-old male with a history of acute lymphoblastic leukemia (now in remissionl, diabetes melitus,and obesity.Anteroposterior (a),lateral (b),and axial (c) radiographs show a lucent area in the central posterior regio
32、n of the right patella,with a halo of sclerosis.Sagital proton density(d),and coronal (e) and acial (f) T2 weighted fat-suppressed images demonstrate a lesion of intermediate and low signal intensity,surounded bya peripheral margin of low signal intensity Dark areas represent bone infarcts.,Fig. 15:
33、 Patellar osteonecrosis 图15：髌骨骨坏死 16岁男孩；急性淋巴结细胞性白血病（现缓解期）、糖尿病、肥胖病史。,Axial radiograph(a) showing slight lateral subluxation of patella with corticated body along the medial patellar facet (arrow), stigmata of dislocation.,Axial radiograph(b)in a different patient shows normal alignment.Note the mild
34、heterogeneity involving lateral aspect of the lateral femoral condyle(white arrow)and the subtle depression in the articular surface of the medial patellar facet(blue arrow,findings reflective of a recent patellar dislocation.,Coronal fat-suppressed proton density (c) and axial fat-suppressed T2-wei
35、ghted(d,elimages demonstrate bone marrow contusions along the medial patellar facet(white arrow) and the lateral aspect of the lateral femoral condyle(blue arrow).There is a partial tear of the medial patellar retinaculum(asterisk),and there is a moderate sized joint effusion with a fluid-fluid leve
36、l (red arrow)representing hemarthrosis.These findings are typical for lateral patellar dislocation.,Fig. 16: Lateral patellar dislocation 图16：髌骨外侧脱位慢性不稳定/复发性脱位患者，如果不积极治疗可能导致进行性软骨损伤和严重骨性关节炎。,Anteroposterior (a)and lateral (b)radiographs in a patiernt presenting with a direct fall onto the patella sho
37、wa comminuted fracture of the patella,with 8 mm of distraction at the mid bone.,Fig. 17: Acute fracture of the patella 图17：髌骨骨折,Three images of a 12-year-old male following a fall who presented with anterior knee pain,swelling,and decreased ambulation.Lateral radiograph(a) shows a minimally displace
38、d fracture of the interior patelia(arrow) with thickening of the patellar tendon and a small knee joint effusion.Sagirtal proton density image(b) shows a tracture at the inferior pole of the patella (arrow)with edema of the patellar tendon.Axtial T2-weighted fat-suppressed image(c) shows edema at th
39、e inferior pole.,Fig. 18: Patellar sleeve avulsion fracture 图18：髌骨袖套状撕脱骨折是儿童特有的一种髌骨骨折。因为髌骨软骨骨转化过程中的髌骨骺生长板，位于其骨化核周缘，骺板的增殖、肥大细胞带和初级钙化带薄弱，常不能耐受剪式应力而分离损伤。当膝关节处于半屈曲位股四头肌强烈收缩时，牵引髌骨向上，而髌韧带固定髌骨形成作用力和反作用力，髌骨下部的软骨受股四头肌强烈收缩而发生的撕脱性骨折，带有少量骨组织或无骨组织被拔除，呈套状。,34-vear-old male presenting with persistent anterior righ
40、t knee pain,associated with knee swelling.locking,and buckling.Sagittal proton density (a)and sagittal(b)and axial (c)T2-weighted fat-suppressed images were obtained showing severe thickening of the proximal patellar tendon and increased signal (arrows),consistent with severe tendinopathy of the pro
41、ximal patellar tendon.,44-year-old male former professional basketball player with chronic knee pain. Lateral radiograph(d)shows diffuse thickening and heterogeneity of the patellar tendon(arrow),with a small mature calcification within the proximal aspect,findings representing chronic tendinopathy.
42、,Fig. 19: Patellar tendinopathy 图19：髌腱末端病（髌腱腱病）,38year-old male following injury to his left knee while playing softball;reports feeling a tearing sensation.Lateral radiograph (a)shows soft issue prominence along the inftrapatellar tencon (astersk) and a subtle transverse lucenm in the inferior pate
43、ltla(white arrow).There is patella alta Sagiftal proton density(b) and sagirtal T2-weighted fat-suppressed (c)MR images show a complete tear of the patellar tendon at the inferior-most aspect of the patela (arrowsl.with retraction inferiorly.There is prominent patella alta.,Fig. 20: Patellar tendon
44、rupture 图20：髌韧带断裂,Active 13-year-old male presenting with ongoing left knee pain.Lateral radiograph (a) shows a small fragment of bone adjacent to lower portion of left patella(arrow)and mild infrapatellar edema.MR sagittal T2-weighted(b) and coronal fat-suppressed proton density(c)images show fragm
45、entation of the inferior patella and mild tendinosis at the patellar insertion of the patella tendon (arrow).,50-year-old patient with chronic anterior knee pain.Lateral radiograph(d)and sagittal proton density MR(e）image show abnormal morphology of the inferior patellar pole with adjacent mature ca
46、lcification,consistent with chronic sequelae of Sinding-Larsen-Johansson syndrome.,Fig. 21: Sinding-Larsen-Johansson syndrome 图21：辛丁一拉森一约翰逊氏病（髌骨骨软骨炎）与胫骨结节骨软骨炎发病机制相同。,Lateral (a) and axial (b)radiographs show significant soft tissue swelling anterior to the patella(arrows).Sagittal T2-weighted(c)and axial T2-weighted fat-suppressed(d)images show an oval-shaped fluid signal structure anterior to the patella representing the fluid-filled prepatellar bursa(asterisk).,Fig. 22: Prepatellar bursitis 图22：髌前滑囊炎,
