Orthopedic Department, Kaohsiung Veterans General Hospital, No.386, Dazhong 1st Rd., Zuoying Dist., Kaohsiung City, Taiwan (Republic of China).
Orthopedic Department, Chi-Mei Medical Center, No.901, Zhonghua Rd., Yongkang Dist., Tainan City, Taiwan (Republic of China).
BMC Musculoskelet Disord. 2021 Aug 30;22(1):748. doi: 10.1186/s12891-021-04630-w.
The fabella is a sesamoid bone in the posterolateral capsule of the human knee joint. In quadrupedal mammals, the fabella is believed to have a role similar to the patella in redirecting extension forces of the knee joint from one point to another. In bipeds, the fabella is not touching the back of the bent knee, and therefore the role in redirecting forces declines. Posterolateral knee pain can be associated with the irritation between the fabella and lateral femoral condyle, a phenomenon also known as fabella syndrome. In cases that are unresponsive to conservative management, surgical fabellectomy can be a successful treatment option. Among the surgical approaches, open resection is most commonly seen. There are also literature reporting arthroscopic-assisted open resection, but seldom mentioned the all-arthroscopic fabellectomy.
We present 3 patients with a long history (> 12 month) of posterolateral knee pain under suspicion of different pain origins. The diagnosis of fabella impingement was eventually made by ruling out of other causes. All the patients underwent all-arthroscopic fabellectomy for diagnosis and treatment. Investigations of the resected fabella suggested chronic impingement with apparent osteophyte formation and cartilage wearing of the articular side. All patients have been continually followed up at our outpatient department and reported to be pain free after the procedure.
In the patients presenting posterolateral pain, fabella syndrome cannot be ignored due to its relative higher presence in Asian population. In our experience, the all-arthroscopic fabellectomy offers a smaller wound size, less post-operative pain, fewer days of hospitalization and quicker time to rehabilitation for the patients with chronic posterolateral knee pain caused by fabella syndrome.
髌骨下极骨（fabella）是人类膝关节后外侧囊内的籽骨。在四足动物中，髌骨下极骨被认为具有类似髌骨的作用，可以将膝关节的伸展力从一个点重新引导到另一个点。在双足动物中，髌骨下极骨不会触及弯曲的膝盖背面，因此其重新引导力的作用下降。膝关节后外侧疼痛可与髌骨下极骨和外侧股骨髁之间的刺激有关，这种现象也称为髌骨下极骨综合征。对于保守治疗无效的病例，手术切除髌骨下极骨是一种成功的治疗选择。在手术方法中，开放性切除术最为常见。也有文献报道关节镜辅助开放性切除术，但很少提及全关节镜髌骨下极骨切除术。
我们介绍了 3 例有长期（>12 个月）膝关节后外侧疼痛病史的患者，这些患者怀疑疼痛来源不同。最终通过排除其他原因诊断为髌骨下极骨撞击症。所有患者均接受全关节镜髌骨下极骨切除术进行诊断和治疗。对切除的髌骨下极骨进行检查，提示存在慢性撞击，表现为明显的骨赘形成和关节面软骨磨损。所有患者均在我院门诊持续随访，术后均报告疼痛消失。
在出现膝关节后外侧疼痛的患者中，由于髌骨下极骨综合征在亚洲人群中相对较高，因此不能忽视。根据我们的经验，对于慢性膝关节后外侧疼痛的患者，全关节镜髌骨下极骨切除术可提供更小的切口、更少的术后疼痛、更少的住院天数和更快的康复时间。
