Entrapment neuropathy of common peroneal nerve by fabella:A case report

BACKGROUND Neuropathy of the common peroneal nerve caused by compression by a fabella is an extremely rare form of compression neuropathy.Involving both the superficial and deep peroneal nerves,it usually manifests as either impaired sensation from the lower lateral leg to the top of the foot or drop foot,or as a combination of both.CASE SUMMARY We report the case of a 58-year-old Asian female who presented with inversion of the right foot during the stance phase of gait without sensory complaints related to the lower leg.Electrodiagnostic testing revealed the neuropathy of the common peroneal nerve at the level of the knee,exclusively affecting the muscular branch of the superficial peroneal nerve.A neuromuscular ultrasound disclosed swelling of the right common peroneal nerve just before it crossed over a large fabella as well as atrophy and fatty infiltration of the right peroneus longus and peroneus brevis muscles.Surgical excision of the fabella and neurolysis were performed.Subsequently,the strength of the right foot evertors improved,but the unsteady gait with occasional falls persisted for nine months after the surgery.Therefore,another procedure was performed to transfer the split posterior tibialis tendon to the peroneus brevis in order to correct the gait.CONCLUSION This is the first case of neuropathy of the common peroneal nerve caused by compression by a fabella affecting exclusively the muscular branch of the superficial peroneal nerve.Clinicians should be aware of this unusual peripheral neuropathy while evaluating and treating patients with gait disturbance.

Fabella Syndrome: A Typical Case of Misdiagnosis and Discussion

Background: Fabella is a natural occurring sesamoid bone, cartilage or a mixture of both that is usually located at the posterolateral corner (PLC) of the knee [1]. Recently the PLC of the knee has been extensively investigated because it is a common site of injuries and diseases [2] [3]. The complexity of PLC anatomy needs to be fully understood because the fabella could be missed diagnosis as an osteochondral defect, osteochondritis dissecans (OCD), calcific tendinitis, or foreign body. We present a case report of fabella syndrome triggered by trauma and also performed a review of literature for the various diagnoses that might be confused with fabella syndrome. Case presentation: A 29-year-old, Sudanese male presented to the trauma center in King Khalid Hospital in KSA, complaining of pain and partial swelling in his left knee joint due to trauma. Fabella was detected in the posterior lateral corner (PLC) of the knee joint embedded in the lateral head of the gastrocnemius muscle. All other pathological conditions were excluded. Conclusion: Fabella is sesamoid bone with variable size, found in the PLC. Commonly if present it causes periodic pain especially in the fully extended knee or it remains asymptomatic. Trauma, surgery, sports or heavy extreme activities may trigger the pain of asymptomatic fabella. Clinicians should consider that pain in the PLC of the knee can result from the presence of the fabella in a condition called fabella syndrome.

腓肠豆骨的解剖学观察及其临床意义

目的：对国人腓肠豆骨进行解剖观察，为临床腓肠豆骨相关疾病诊治提供解剖学参考依据。方法：对61侧成年膝关节标本进行解剖，观察腓肠豆骨的出现率、形态及其与周围相关结构的关系。结果：外侧腓肠豆骨的出现率为86．89％，且以骨性多见（55．74％），而内侧出现较少（9．84％），且均为软骨性。腓肠豆骨与腓总神经毗邻，20．8％的腓总神经从其表面通过。腓肠豆骨的存在与腓肠豆韧带的出现并不相关，不能作为判断腓肠豆韧带是否存在的标志。结论：国人腓肠豆骨以外侧多见，与腓总神经关系密切，临床医生需要对此结构有一定的认识，以利腓肠豆骨相关疾病的诊治。

腓肠豆发生与膝关节后外侧疼痛和腓总神经损伤相关性研究

目的:分析中国人群中膝关节腓肠豆的发生率、特点及其与膝关节后外侧区域疼痛、腓总神经麻痹等症状之间的相关性。方法:选取自2015年9月至2019年7月就诊行单侧或双侧膝关节MRI检查的732例患者,男405例(450膝),女327例(383膝),进行回顾性评估。所有患者的基本信息来自于医院HIS系统提取,电话随访或HIS系统查看患者病历并记录出现膝关节后外侧区域疼痛、腓总神经麻痹等症状患者的例数。结果:对833膝关节进行统计分析,腓肠豆出现的整体流行率为48.38%,男性中出现率为23.53%,女性中出现率为24.85%,两者之间差异无统计学意义(P>0,05)。将所有研究对象细分为5个年龄组,不同年龄组之间腓肠豆的流行率存在明显差异:≤20岁6.6%,21~34岁33.8%,35~44岁53.5%,45~59岁57.5%以及≥60岁73.9%,各组差异有统计学意义(P<0.001)。腓肠豆的流行率与其患者年龄具有明显相关性,随着患者年龄的增加,膝关节腓肠豆的流行率也呈现明显的上升趋势(P<0.001)。按膝关节是否存在腓肠豆对全部资料进行分组,发现当腓肠豆存在时共232例膝关节患者感疼痛,占腓肠豆存在患者的57.57%,占全部资料的27.85%(P<0.01),对其进行相关性分析R=1.546,P<0.01;当膝关节存在腓肠豆时,共有44例膝关节出现腓总神经麻痹的症状,占全部膝关节的5.28%,而当膝关节无腓肠豆出现时有29例出现腓总神经麻痹的症状,占全部膝关节的3.48%(P<0.05),对其进行相关性分析R=1.695,P<0.05。结论:腓肠豆在中国人群中的流行率为48.38%,腓肠豆的发生率与性别之间没有关系,但是腓肠豆的发生率却与年龄、膝关节后外侧区域的疼痛及腓总神经症状的出现具有正相关性。

腓肠豆骨的形态学特点及其临床意义研究进展

目的：总结腓肠豆骨的形态学特点及其临床意义.方法：广泛查阅近几年关于腓肠豆骨的解剖学以及临床研究相关文献,归纳总结其形态特点及临床意义.结果：腓肠豆骨为膝关节不恒定出现的籽骨,以往其临床意义常被忽视.但由于其能引起腓肠豆综合征、腓总神经麻痹,且与膝关节炎发生有关,逐渐受到重视.结论：腓肠豆骨病变可造成膝关节疼痛,但常被误诊为其他常见疾病.医生应充分认识腓肠豆骨可能造成病变,并且对此引起重视.