Snapping Biceps Femoris Tendon
Author’s Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article. The views, opinions, and items discussed are those of the authors and do not reflect the work of the United States Government.
Dr. Ernat and Dr. Galvin are Orthopedic Surgeons, Blanchfield Army Community Hospital, Fort Campbell, Kentucky.
Address correspondence to: MAJ Justin J. Ernat, MD, Blanchfield Army Community Hospital, 650 Joel Dr., Fort Campbell, KY 42223 (tel, 815-252-9486; email, Justin.firstname.lastname@example.org).
Am J Orthop. 2018;47(7). Copyright Frontline Medical Communications Inc. 2018. All rights reserved.
A 23-year-old male active duty soldier presented with a biceps femoris tendon snapping over the fibular head with flexion of the knee beyond 90°. Surgical release of anomalous anterolateral tibial and lateral fibular insertions provided relief of snapping with no other repair or reconstruction required. The soldier quickly returned to full running and active duty.
Snapping biceps femoris tendon is a rare but potential cause of pain and dysfunction in the lateral knee. The possible anatomical variations and the cause of snapping must be considered when determining the operative approaches to this condition.
- Snapping biceps femoris is a rare, but debilitating condition.
- Understanding the pathology from an anatomical perspective is key.
- For bone abnormalities, correct the bony pathology to relieve the snapping.
- For soft tissue abnormalities, both excisional and reconstructive approaches can be utilized.
- Preservation of normal anatomy, when possible, can help expedite recovery.
Snapping in the knee is not as common as in other joints, such as the hip or ankle. The snapping sensation can occur from several pathologies, including the following: lateral meniscal tears, iliotibial band syndrome, proximal tibiofibular instability, snapping popliteus, peroneal nerve compression/neuritis, lateral discoid meniscus, rheumatoid nodules, plicae, congenital snapping knee, exostoses, or previous trauma.1,2 A detailed history must be provided, and physical examination and appropriate imaging must be performed to narrow down the differential diagnosis and prescribe the appropriate course of treatment for snapping.
Snapping biceps femoris syndrome is a rare cause of knee snapping. This condition has been described in various case reports.2-13 The reasons for a snapping biceps femoris can vary, and the treating provider must be ready to accommodate and treat these causes. The symptoms typically include an audible, and usually visual, lateral snapping distal to the knee joint and over the fibular head. Imaging may reveal bony abnormalities such as fibular exostoses. Magnetic resonance imaging (MRI) can aid in determining any anomalous or abnormal insertions of the biceps femoris tendon. The snapping can be debilitating, particularly in athletes or patients with high-demand occupations, and surgical intervention is often warranted.
We present a case of an active-duty military service member with symptomatic unilateral snapping biceps femoris and review the literature for treatment of this condition. Surgical release allowed the patient a quick and unrestricted return to full mission capabilities.
The patient provided written informed consent for print and electronic publication of this case report.
A 23-year-old active-duty soldier presented to the orthopedic clinic with several months of noticeable snapping and pain over the lateral knee with attempted running and deep squatting activities, resulting in difficulty to perform his army duties. The patient reported no history of antecedent trauma. No locking of the knee or paresthesia distally into the leg or foot was observed.
The physical examination revealed a palpable and observable snapping of the long head of the biceps tendon over the fibular head with squatting beyond 90° in the left knee. (Video 1). The patient presented with full strength and no instability or joint line pain throughout the knee. Application of a posterior-to-anterior directed force over the biceps femoris proximal to the insertion allowed the patient to perform a deep squat without snapping. The radiographs demonstrated no abnormal fibular morphology (Figures 1A, 1B). Axial MRI images demonstrated an anomalous slip of the tendon inserting on the anterolateral aspect of the proximal tibia in addition to the normal insertion on the posterolateral and lateral edge of the fibular head (Figure 2) as described by Terry and LaPrade.14
A conservative treatment with physical therapy, activity modification, and a Cho-Pat knee strap (to provide a posterior-to-anterior buttress and to prevent snapping) was attempted for 4 weeks. However, the patient could not tolerate the strap, and the activity restraints prevented him from performing his job as an active-duty soldier. Given the failure of conservative treatment, operative intervention was elected.
Upon exploration of the biceps femoris insertion, the accessory anterolateral tibial insertion was readily identified (Figure 3). Notably, the expected normal lateral edge insertion was thickened and extended beyond the lateral edge, distal, and anterior on to the fibular head (Figure 4, Video 2). The anterolateral tibial band was released first. However, the snapping remained evident. The thickened anterior fibular accessory band was then released back to its normal, lateral edge, and at this point, no further snapping was observed with deep flexion of the knee (Video 3). Inspection of the remaining posterolateral and lateral edge insertion demonstrated a healthy, 1-cm thick tendinous insertion. The accessory slips were completely excised, and the incision was closed without any additional repair or re-insertion (Figure 5). The patient presented no complications postoperatively. He was allowed to bear weight as tolerated and was limited to stretching and gravity resistance training for 4 weeks. At 1 month, the patient was released to progress back to full activity (Video 4). By 8 weeks postoperative, he remained free of snapping and resumed his regular running routine and military duties without restriction or pain.
Release of the anomalous bands with no further repair or re-insertion of the biceps femoris allowed this active-duty soldier to resume full running and duty-related activities in <2 months. In this particular patient, given his anatomy, the treatment was successful. The literature indicates that optimal results and surgical approach depend upon the pathological anatomy encountered.
Date and colleagues4 described a similar anatomical anomaly as with our patient, whom after the release of tibial insertion, snapping was still observed, thus requiring the release of anterior fibular insertion. They noted the necessity of suturing the accessory limbs onto the periosteum of the fibular head to achieve a stable biceps femoris.
In other cases, abnormal bony anatomy of the fibula has been shown to cause snapping. Vavalle and Capozzi5 described a case of snapping biceps in a marathon runner, who needed partial resection of the fibular head to eliminate snapping. The runner made a full return to the sport. Fung and colleagues2 described a similar approach to a 17-year-old cyclist; however, this patient presented exostoses of the bilateral fibular heads. The exostoses were bilaterally excised, and the snapping ceased. Kristensen and colleagues13 described a patient with an anomalous tibial insertion. Rather than releasing the tibial insertion, a partial resection of the fibular head allowed for cessation of snapping.
Other authors advocate the detachment and anatomic re-insertion of the biceps femoris into the fibular head. Bernhardson and LaPrade6 reported a series of 3 patients requiring this approach with excellent results. Bansal and colleagues8 were the first to describe a soccer player with an isolated injury to the knee as a traumatic cause for a snapping biceps femoris. After failure of conservative treatment attempts, exploration and re-insertion through a bone tunnel allowed for return to the sport. Hernandez and colleagues11 and Lokiec and colleagues12 both described the reproduction of the normal biceps femoris anatomy through re-insertion procedures after identifying patients with abnormal anatomical insertions as causes for snapping.
We presented a case of an active military service member with a unilateral snapping biceps femoris tendon due to an anomalous distal insertion on both the proximal tibia and anterior fibular head. The release of abnormal insertions and maintenance of his normal anatomical insertion allowed for a quick and effective return to running and duty at full capacity. Although other surgical approaches have been described to include partial fibular head resection or anatomical re-insertion, we believe that the approach to this rare condition should be anatomy-based as the causes of snapping can significantly vary. We believe that if the normal posterolateral and lateral edge insertions of the biceps femoris are intact, removal of the abnormal anatomy without any repair or reconstruction can safely lead to successful surgical outcomes.