Snapping Biceps Femoris Repair: A Rare Cause of Lateral Knee Pain

Abstract

Background:

Snapping biceps femoris syndrome (SFS) represents a rare clinical entity in which the biceps femoris subluxates over the fibular head in deep flexion. Two primary pathophysiologies have been described including a prominent or abnormal fibular head morphology. Others have implicated an anomalous biceps femoris insertion. The diagnosis is made clinically, with operative and nonoperative intervention strategies available for treatment.

Indications:

SFS often results in audible snapping and associated pain at the lateral fibular head. When recalcitrant to nonoperative management, surgical intervention can lead to resolution of symptoms. We present the case of a college-aged male who has bilateral symptoms, worse on the right, which have resulted in significant activity modification and daily discomfort recalcitrant to anti-inflammatory medication and physical therapy.

Technique Description:

The patient was placed supine on the operating room table with an ipsilateral bump under the hip to assist in exposure of the lateral aspect of the knee. Examination under anesthesia (EUA) confirmed the snapping biceps femoris. A lateral approach to the knee and a common peroneal neurolysis was performed. The biceps femoris insertional anatomy was examined for anomalous tendon insertion or insertional tearing. The prominent fibular head was exposed and resected, with careful attention not to disrupt the lateral collateral ligament or popliteofibular ligament insertion sites. The biceps femoris was then repaired to the prepared bony bed of the fibula with one double-loaded suture anchor. Repeat EUA confirmed complete resolution of snapping even with maximal internal rotation of the tibia; this was carefully examined again with the tourniquet deflated to ensure its compressive effect was not partially responsible for the resolution.

Results:

Published data pertaining to SFS is limited to case reports and small case series. With appropriate indications, surgical intervention yields promising results with a high percentage of patients returning to prior level of activity or prior participation level in sport.

Discussion/Conclusion:

SFS can be diagnosed with a careful clinical assessment. When recalcitrant to nonoperative management, it is effectively treated with surgical intervention to restore normal fibular anatomy, and prevent recurrent instability and persistent pain. The presented technique allows for appropriate management of these rare injuries.

Patient Consent Disclosure Statement:

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract

This is a visual representation of the abstract.

Video transcript

This video illustrates the surgical technique for a snapping biceps femoris repair using a lateral approach to the knee as performed by the senior author.

The authors’ financial and professional disclosures can be seen here.

This video will aim to provide pertinent information regarding the snapping biceps femoris syndrome (SFS). We will then present a case and discuss the pertinent findings. We will discuss clinical tips and radiographic imaging for careful evaluation relevant to snapping biceps femoris-type injuries. Following this, we will provide video demonstration of the surgical approach and repair using a lateral approach to the knee. Briefly, we will comment on the postoperative rehabilitation course, with focus on return to play and existing literature regarding snapping biceps femoris repairs in athletes.

Background

Several snapping tendon phenomena have been described. The snapping is often caused by a tendon that subluxates over a bony prominence through an arc of motion. Although commonly associated with the iliopsoas tendon in the hip, this phenomenon has also been described about the knee. In SFS, the biceps femoris subluxates over the fibular head in deep flexion. ¹ The diagnosis is made clinically and surgical intervention can resolve cases recalcitrant to nonoperative interventions.^2,4 Maximal tibial internal rotation can accentuate the snapping and often manual compression of the tendon at the fibular head can eliminate the snapping. There remains a paucity of literature and outcomes data regarding snapping biceps femoris repair given the rare occurrence of this pathology.

This case example is of a 19-year-old male, recreational lifter, and computer science student who presented with right knee pain. He reported painful snapping of his right biceps femoris for over a year, which developed gradually with no acute mechanism of injury. He reportedly has had to stop power-lifting; at this point simply walking across campus is quite painful for him, and his activities of daily living are limited by this issue. He has seen other providers, attempted activity modification and physical therapy, and had a corticosteroid injection of his biceps femoris which provided him with symptomatic relief for 1 to 2 months followed by symptom recurrence. At this point, he notes a pronounced non-painful subluxation on the left knee as well. He presents today for further evaluation and options for management of his right knee.

For SFS, a careful, detailed history is critical for diagnosis with certain clinical findings which are fairly typical. Range of motion testing, palpation, strength testing, and special tests were performed on this patient as part of a standard knee examination. As is common, his physical examination findings overall were fairly benign. However, he had clear snapping of the biceps femoris in deep flexion, between 90° and 100°. Furthermore, that snapping was more prominent with maximal tibial internal rotation. It is important to document the range of motion at which the snapping occurs for later reference in the operating room when treated surgically. There was a similar, but less impressive snapping on the patient's contralateral side, and the patient was tender to palpation over the fibular head. Based on these findings and the inability to manage this successfully with nonoperative options, the decision was made to proceed with imaging in the form of radiograph and magnetic resonance imaging (MRI).

Radiographs demonstrate the size and shape of the fibular head, and MRI may show an anomalous insertion or tearing of the biceps femoris.^2,4 In this case, we obtained a standard set of knee radiographs including an anteroposterior (AP) and lateral, shown here, as well as the Rosenberg and sunrise views not pictured. In this case, the radiograph findings were largely unremarkable, with the exception of some increased prominence of the fibular head laterally. MRI for this particular patient was unremarkable.

MRI evaluation of the tendon in the coronal and axial planes is identified here, with the biceps femoris tendon highlighted in blue as shown here. Axial slices demonstrated on the right correspond to the color-coded planes shown on the coronal section on the left.

Given no alternative pathology noted on radiological examination and the patient's clinical examination findings, as well as the failure of nonoperative intervention in this case, the joint decision was made to proceed with surgical management. The plan was to perform an outpatient surgical procedure using general anesthesia and a postoperative peripheral nerve block as a potential adjunct. The senior author prefers supine positioning, with an ipsilateral bump and a leg holder. The planned operative technique was to perform a lateral approach to the knee, common peroneal nerve neurolysis, and fibular head resection with or without repair of the biceps femoris tendon.

Demonstrated here is a patient provided video of his biceps femoris snapping with repeated flexion arc of motion. Demonstrated here is our examination under anesthesia. Note that the tibia is being held in maximum internal rotation to accentuate biceps femoris snapping. We are referencing our preoperative clinical evaluation for the degrees at which the snapping was most prominent in the office.

Technique Description

This represents the senior author's preference for patient positioning. Supine with a lateral leg bolster. The incision marked in full extension just anterior to the fibular head and the use of an Alvarado leg holder.

Superficial dissection is carried out and the operation begins with identification of the common peroneal nerve. Careful dissection posterior to the biceps femoris reveals the common peroneal nerve in its usual anatomic location. Once the nerve has been safely identified and protected with a Penrose drain, we then confirm intraoperatively the snapping biceps femoris as shown here. The prominent fibular head noted on the radiograph is identified intraoperatively. There is also substantial bursal tissue just posterior to the biceps femoris from the recurrent snapping which is important to resect.

Here, you can visualize a rongeur being used to remove the prominence of the posterior fibular head and prepare the site for biceps femoris repair if needed.

After resection of the prominent posterolateral fibular head, the knee is then taken through a full arc of motion with the tibia held in maximal internal rotation to accentuate any potential biceps femoris snapping. You can already visualize a drastic change in the physical examination after resection.

Biceps femoris repair in a more appropriate anatomic location is then carried out with the use of double-loaded corkscrew anchors placed into the prepared posterolateral fibular head. The suture tapes are then passed through the biceps femoris tendon using a free needle in a mattress fashion as pictured here. These are then tied in full extension in order to recreate more normal anatomic relationship.

The final repair construct is demonstrated here showing the recreation of the footprint of the biceps femoris on the proximal lateral aspect of the fibular head.

The leg is then taken through range of motion again with the tibia in maximal internal rotation and no biceps femoris snapping or subluxation is identified. At this time, satisfied with the results of our surgical intervention, the Penrose drain is removed and the lateral approach is closed in layers.

Results and Discussion

Postoperatively, the patient was placed into an incremental range of motion (IROM) brace. The postoperative rehabilitation protocol emphasizes protection of the biceps femoris tendon repair. As such, partial weightbearing and avoidance of active hamstring activity are emphasized. This is followed with guided return to full range of motion and weightbearing. Active hamstring exercises are avoided until the 12-week mark postoperatively. The goal for return to sport-related activity is usually around 4 or 5 months with progression back into full-contact athletics. Return to sport is largely dependent on the type of sport, level of contact, and type of knee activity that is required for the athlete.

Published outcome studies are rare following surgical treatment of SFS. In 2021, Catonne et al ³ published results on 6 patients (9 knees) who were surgically managed for SFS. They also included a review of the available literature. In their study, Catonne et al ³ reported all patients with snapping biceps femoris to be male, with a mean age of 29 years, treated with release and reinsertion of the biceps femoris tendon to the fibular head. All patients were able to return to sport. The literature review yielded 24 cases of snapping biceps femoris, with between 1 and 3 cases per author. All studies reported surgery as highly effective on snapping and pain, and patients returned to sport at their previous level in all cases. More high-quality evidence is necessary regarding this topic.

Our references are listed here.

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