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.
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. 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
Continue to: A conservative treatment with physical therapy...