Popliteal Cysts: A Current ReviewAlyssa M. Herman, BS; John M. Marzo, MDZhu xi The Orthopaedics of General Hospital of NMUThe authors are from the Department of Exercise and Nutrition Sciences (AMH) and the Department of Orthopaedics (JMM), University at Buffalo, Buffalo, New York.OrthopedicsAbstractOf the possible cystic lesions around the knee joint, popliteal cysts are the most prevalent.Popliteal cysts most commonly form by distention of the gastrocnemio-semimembranosus bursa, which is located in the medial aspect of the popliteal fossa.These cysts are also referred to as Bakers cysts, a name given to the condition after Bakers classic case description of popliteal swelling腘窝囊肿是膝关节周围最常见的囊性病变。腘窝囊肿通常由腘窝内侧的腓肠肌 - 半膜肌滑囊膨胀形成，最早由 Baker 报道，又称 Bakers 囊肿。AbstractThe gastrocnemio-semimembranosus bursa is situated between the tendons of the gastrocnemius and semimembranosus muscles and is a normal anatomic finding.腓肠肌 - 半膜肌滑囊是位于腓肠肌、半膜肌肌腱之间的正常解剖组织。AbstractThis bursa has been found to communicate with the knee joint capsule via a transverse opening in the posterior capsule at the level of the medial femoral condyle, where the gastrocnemius tendon merges with the joint capsule.该滑囊通过一横孔与膝关节囊腔相通，横孔位于股骨内侧髁水平处的关节囊后部。且腓肠肌肌腱与膝关节囊在股骨内侧髁处相连。AbstractMost often, this opening takes the shape of a horizontal slit measuring 4 to 24 mm.The communication between the bursa and the joint capsule is almost nonexistent in children, and the presence of this opening increases in frequency with age.横孔通常是 4 到 24 毫米大小的水平裂缝。滑膜囊腔通常在儿童阶段并不与关节腔相通，随着年龄的增加，出现缺口的几率也增加。AbstractThe integrity of the joint capsule decreases with age, and it is theorized that this opening results from a tear in the degenerated joint capsule. Rauschning observed that, when no opening was found, capsular thinning was seen in the same area and noted that the cyst is simply a herniation of synovium, as originally postulated by Baker.膝关节囊完整性随着年龄增加而减低，有理论认为缺口是由于退化的膝关节囊撕裂后所致。Rauschning 观察到，对无关节缺口的人群，在囊肿的同一区域仍可观察到关节囊，提示腘窝囊肿可能是贝克最初假设的滑膜疝出所致。Abstract A true ganglion cyst can form, usually by fluid leakage through a horizontal or oblique medial meniscus tear, forming a wall of dense fibrous connective tissue (not synovium) as a distinguishing feature (Figure 1).真正腱鞘囊肿通常是液体从斜行或水平内侧半月板裂隙渗出形成，其明显的特征是形成厚厚的纤维连接组织壁（不是滑膜）（图.1）。AbstractAbstractThe communication between the gastrocnemio-semimembranosus bursa and the joint capsule, which allows for the movement of synovial fluid between the 2 spaces, has been shown by arthrography. A valvelike mechanism that allows only unidirectional flow from the joint into the bursa has been found in some of these openings.关节造影术显示，关节液在腓肠肌 - 半膜肌滑囊与膝关节囊互通的两个腔隙之间运动。在有些互通缺口中发现类瓣膜机制，只允许关节液单方向流向滑囊。Abstract Intra-articular and intracystic pressure measurements have been made in the knees of patients with rheumatoid arthritis who have popliteal cysts，and in every case intracystic pressure was higher than intra-articular pressure.These findings of fluid accumulating in the popliteal cyst and not being able to leave, despite high pressure, indicate the presence of a 1-way valve-type mechanism.测量类风湿患者腘窝囊肿内压和关节内压发现，所有患者囊肿内压高于关节内压。这些发现提示，液体积聚在囊肿内，尽管内压高，但并不流走，表明存在单向瓣膜机制。Clinical PresentationIn children, a popliteal cyst is most often an incidental finding on physical examination. Occasionally a child or parent sees or feels a cyst and becomes concerned about the presence of a mass.儿童中，腘窝囊肿常在体检中偶然发现。有时父母因肿块（囊肿）发现囊肿。Clinical PresentationTypical adult clinical presentation is vague posterior knee pain, possible localized swelling or mass, and a feeling of tightness in the popliteal region. Physical examination may show a tender palpable mass in the medial popliteal fossa, although this finding is subjective and is somewhat dependent on the physicians opinion and experience。成人临床常表现为膝后部隐约痛，局部肿胀及肿块，腘窝区域紧张感。物理查体可以发现在内侧腘窝可触及柔软肿块。这还有赖于医生主观的经验。Clinical PresentationMost cysts are found on the medial side of the posterior knee and are reported more rarely on the lateral side.The cyst is usually rounded, smooth, and fluctuant, and may feel tense in extension, but this is a difficult finding to quantify.This hardness of the cyst in full extension followed by softening with knee flexion is known as Fouchers sign囊肿在膝关节后内侧，很少在外侧，呈圆形，光滑，波动感，扩张时可能紧张，但是这很难量化。膝关节伸直时，囊肿变硬，屈曲时软化，称为 Foucher 征。Clinical Presentation Calf pain and swelling are also present in DVT or superficial thrombophlebitis, and the clinical imperative is to rule out DVT with appropriate diagnostic imaging studies.Pseudothrombophlebitis has the same clinical presentation as DVT or superficial thrombophlebitis, but is caused by another condition，such as a ruptured popliteal cyst.DVT 和表浅性血栓静脉炎也会出现上述症状，因此影像学检查排除 DVT 很有必要。假性血栓性静脉炎临床表现同 DVT 和表浅性血栓静脉炎相同，比如破裂的腘窝囊肿就可以引起。Clinical PresentationDiscoloration or ecchymosis in the calf, at the medial malleolus, or on the dorsum of the foot is a distinguishing feature of a ruptured cyst because bloody synovial cyst fluid dissects inferiorly.Treatment of ruptured cysts typically involves treating resultant complications, but ruptured cysts without complications have been reported to resolve spontaneously with supportive conservative care, such as compression and elevation of the limb.在小腿，内踝或是足背出现变色或是瘀斑是囊肿破裂的特异性特征。囊肿破裂后治疗通常是治疗相应的并发症，然而无并发症的破裂囊肿在保守支持治疗下可自行缓解，如抬高或加压患肢。Diagnostic ImagingMultiple imaging techniques may be used in the diagnosis and assessment of a popliteal cyst.Plain radiographs are simple and readily available, but they provide limited information about the popliteal cyst. However, they may help in identifying associated articular disorders, such as loose bodies in the cyst or the general findings of osteoarthritis and inflammatory arthritis. 诊断和评估腘窝囊肿可采用多种影像学方法。平片简单易行，仅能提供有限的信息。但有助于鉴别相关关节疾病，如囊内游离体，骨关节炎，关节炎。Diagnostic Imaging Other imaging techniques are often more suitable for diagnosing popliteal cysts. Previously, arthrography was commonly used in the imaging of popliteal cysts, but disadvantages such as the invasiveness of the procedure and the possibility of contrast extravasation have been made apparent.其他影像学方法更适于诊断腘窝囊肿。以前常采用关节造影术，但有如操作创伤性及造影剂可能外渗等缺点。Diagnostic ImagingUltrasound quickly became a popular replacement for arthrography in imaging for the presence of popliteal cysts. Ultrasound is readily available, relatively inexpensive, and noninvasive, and it involves no exposure to radiation. 由于超声简单易行，相对便宜，非创伤性，无辐射，因此很快替代关节造影检查。Diagnostic ImagingUltrasound, however, is not sensitive to intra-articular lesions, and so further imaging is needed to confirm the presence of an associated internal derangement.然而超声对关节内病变不敏感，因此需要进一步辨别相关关节内部疾病。Diagnostic ImagingMagnetic resonance imaging is considered the gold standard in the visualization and characterization of masses about the knee.A distinct advantage of MRI is the ability of axial images to visualize a fluid-filled neck of the cyst communicating with the joint (Figure 1).MRI 是鉴定膝关节周围肿块的金标准检查。MRI 独特的优点是轴向显现囊肿与关节交通处充满液体的颈部（图.1）。Diagnostic ImagingTreatment and OutcomesThere are many treatment options for popliteal cysts, dictated by the underlying cause and associated condition. Sometimes no treatment or simple supportive measures result in spontaneous resolution of the cyst or at least reduction in associated symptoms. If not, both minimally invasive and surgical techniques are alternatives.治疗腘窝囊肿的方法取决于潜在病因及相关疾病。有时不治疗或简单支持治疗也可以缓解腘窝囊肿症状。若保守治疗无效，微创或外科手术均可选择。Treatment and OutcomesUltrasound-guided aspiration with corticosteroid injection is a relatively low-risk and successful procedure for the treatment of knee osteoarthritis complicated with a popliteal cyst.Another option is a similar procedure in which corticosteroid is injected directly into the popliteal cyst. 超声引导抽吸术并注射皮质激素治疗膝关节炎并发腘窝囊肿是一个低风险和较成功的方法。另一相似方法是直接向腘窝囊肿内注射皮质激素。Treatment and OutcomesMore recently, intra-articular corticosteroid injections were compared with intracystic corticosteroid injections in patients with knee osteoarthritis.Although both methods are suitable treatment options in patients with knee osteoarthritis, direct injection into the popliteal cyst may provide greater reduction in cyst size.最近，对关节内注射与囊内注射皮质激素治疗效果进行了比较。虽然这两种方法是治疗膝关节骨性关节炎患者合适的治疗方案，但是囊内直接注射会更大地减小囊肿尺寸。Treatment and OutcomesAlthough conservative and minimally invasive measures are available to treat some of the conditions associated with popliteal cysts, not all may improve without invasive intervention. Currently, arthroscopic procedures are most commonly used to treat the conditions associated with popliteal cysts and to address cysts directly. 尽管保守和微创治疗适用于某些腘窝囊肿患者，但有些患者尚需手术干预。目前，关节镜最常用于治疗腘窝囊肿，直接处理囊肿。Treatment and OutcomesThe primary goal of surgical intervention in symptomatic popliteal cysts is to resolve the underlying intra-articular pathology and reduce chronic effusion. Others believe that popliteal cysts are best treated by closing the communication to the cyst.手术治疗的主要目标是解决潜在关节内病变及减少关节慢性渗出。也有一些学者认为，腘窝囊肿最好的治疗方法是闭合囊肿与关节之间的交通。Treatment and OutcomesPatients were treated arthroscopically for meniscal tears, chondral lesions, or a combination. In addition to these procedures, an arthroscopic suturing technique via an accessory posteromedial working portal was performed to close the communication into the popliteal cyst (Figure 2).患者均采用关节镜治疗半月板撕裂，软骨损伤，或两者同时存在，经后内侧入口关节镜下缝合囊肿与关节交通处（图.2）。Treatment and Outcomes图.2 关节镜下修复腘窝囊肿瓣膜开口。穿过可吸收缝线（A）, 使用探针钩回缝线（B），打结关闭囊肿开口（C）。Figure 2：Technique of arthroscopic repair of the valvular opening into a popliteal cyst. Passing of an absorbable suture (A). Retrieval of sutures with a hook probe (B). Final repair with knots closing the cyst opening (C). Treatment and OutcomesOther approaches go a step further and include cystectomy in addition to arthroscopic treatment of internal joint derangements. One study examined the outcome of resection of the valvular opening with excision of the wall of the cystic cavity when a fibrous membrane, septae, or nodules were seen in the cyst. Follow-up MRI at an average of 8.6 months showed that the cyst had disappeared in 55% of patients and had significantly reduced in size in the remaining 45%.还有一些手术方法 ，除了处理关节疾病，又切除囊肿。一项研究使用的方法切除范围包括纤维膜，隔膜及囊肿内结节。术后 8.6 个月 MRI 随访发现，显示 55% 患者囊肿消失，其余 45% 囊肿变小。Treatment and OutcomesArthroscopic intervention is favored over open excision because of the successful outcomes of arthroscopic treatment for conditions associated with popliteal cysts. Arthroscopy is minimally invasive, is associated with lower risk, directly addresses both intra-articular pathology and the cyst, and allows early aggressive rehabilitation.由于关节镜治疗创伤小，低风险，直接解决关节内病变及囊肿，并为早期康复创造机会，因此关节镜治疗腘窝囊肿效果优于开放性手术。