Isolated biceps femoris tendon injury is rare; most commonly, injury occurs at the knee during dislocation or multiligamentous injury. Most cases reported are sports related, with a mechanism of injury typically involving hyperextension with valgus or varus stress1-3 or flexion against resistance3. On examination, resisted flexion of the knee is grossly diminished, with a palpable gap and/or retracted muscle belly. There is very little literature regarding the treatment and outcomes of isolated distal biceps femoris tendon injury1-3. We present a case of complete, traumatic transection of the distal biceps femoris tendon 8 cm proximal to its insertion with concomitant peroneal neuritis, successfully treated with primary repair and peroneal neurolysis 3 months after injury. To our knowledge, this injury and treatment have not been previously reported.
The patient was informed that data concerning the case would be submitted for publication, and he provided consent.
A 22-year-old man presented to the clinic 3 months after sustaining a laceration to his right, posterolateral knee by a skate while playing hockey (Fig. 1). At the time of injury, he was evaluated in a local emergency department and underwent wound irrigation and closure. Three months after injury, the patient presented to the clinic with the inability to skate. Three previous orthopaedic surgeons had offered treatments including platelet-rich plasma (PRP) and continued physical therapy, but the patient elected not to undergo PRP treatment. He endorsed persistent weakness, pain, and swelling in his posterior knee; had plateaued with physical therapy despite extensive rehabilitation guided by his team's athletic trainer and physical therapist; and was unable to return to skate at the level required for collegiate hockey. Clinically, there was a healed oblique laceration in the lateral aspect of the popliteal fossa. Resisted knee flexion produced 4/5 strength and severe pain in the posterolateral knee; the biceps femoris tendon was not visible or palpable. He described decreased sensation over the dorsum of the foot, the first dorsal webspace, and the lateral lower leg, present since the time of injury. There were no appreciable distal motor deficits. Ultrasound imaging and magnetic resonance imaging (MRI) revealed a complete transection of the biceps femoris 8 cm proximal to the fibular attachment, with 5 cm retraction (Figs. 2-A and 2-B). MRI showed an intact common peroneal nerve (CPN). Surgical and nonsurgical treatment options were discussed with the patient as well as the expectations of surgical intervention, and he elected to proceed with surgery.
Magnetic resonance imaging (1.5T) of the left knee, with coronal (Fig. 2-A) and sagittal (Fig. 2-B) cuts demonstrating transected biceps femoris tendon with retraction (arrows); common peroneal nerve was not clearly visualized.
The patient was subsequently taken to the operating room for distal biceps femoris repair and CPN neurolysis. Under general anesthesia and with the patient in left lateral decubitus position, a 15 cm hockey stick incision was made posterior to the IT band fascia to the level of the fibular head. Dissection was taken down to the fascia, which was incised (Fig. 3). Proximal to the zone of the injury, the biceps femoris tendon was identified. The CPN was found to be intact, and surgeons performed a common peroneal neurolysis from the level of injury to the fibular neck. Attention was then taken to the biceps femoris tendon injury, which correlated with the MRI findings of 5 cm retraction (Fig. 4). Scar tissue was debrided, and the tendon was mobilized proximally and distally. Two #2 FiberWire running Krackow stitches were placed proximally, then distally in the proximal segment. Similarly, this technique was repeated in the distal segment running distally, then proximally. The ends of the tendon were approximated with the knee in 90° of flexion. Two #1 Polysorb stitches were then placed in a figure-of-eight fashion for additional support. After this, the knee was ranged with minimal tension on the repair to 30° knee flexion (Fig. 5). Throughout the procedure, the CPN was protected. A layered closure was performed with 2-0 Polysorb, followed by interrupted mattress #2 Surgipro. The knee was immobilized in 90° flexion in a hinged knee brace. Postoperatively, the patient gradually increased knee extension by 15° per week, with a total of 6 weeks in the brace.
At his 3-month follow-up, the patient was progressing well with the therapy, with minimal pain; active hamstring strengthening activities were initiated at that time. At 6 months, the patient returned to skating. He demonstrated full active motion of the knee and a normal gait, with 5/5 strength resisted knee flexion at 45°/90° compared with the contralateral extremity; clinically, the continuity of the tendon was intact. The patient returned to unrestricted hockey 9 months postoperatively and completed a full collegiate hockey season without limitation.
The biceps femoris is positioned in the posterolateral thigh and originates at 2 heads. The long head originates at the ischial tuberosity in a tendon common with the semitendinosus. The short head originates at the linea aspera, lateral supracondylar ridge of the distal femur and intermuscular septum. Distally, the biceps femoris inserts at the lateral head of the fibula, with lesser attachments on the lateral collateral ligament and lateral tibial condyle.
The biceps femoris is the strongest knee flexor, also contributing to hip extension and knee external rotation. It is a major contributor to the overall strength of the hamstring musculature, contributing up to 75% of the overall strength of knee flexion4. The biceps femoris is also an important dynamic stabilizer of the knee5. Given its functional importance in sporting activities, in a young patient with high functional demands, surgery may be required to restore normal anatomy.
Biceps femoris muscle belly injury or tendon inflammation in athletics is not unusual. Injury to the biceps femoris tendon in isolation is rarer. Several case reports have described isolated biceps femoris injury at the myotendinous junction6,7, avulsion at its insertion1,2, and spontaneous rupture near distal insertion3.
To date, literature is scarce regarding the management of distal biceps femoris injury. Surgical techniques and outcomes are lacking, with no consensus on the appropriate treatment1-3,7-9. There are only 2 cases of biceps femoris tendon rupture in the literature treated nonoperatively, with resultant mild flexion deficits compared with the other knee3,8. Fortems et al. described a 14% flexion deficit and 12% extension deficit compared with the other knee, using Cybex isokinetic dynamometry3. Watura et al. described rupture of the biceps femoris tendon 20 mm from the fibular insertion in a hockey player, with good recovery and return to recreational hockey after nonoperative management, although with permanent subjective weakness in the injured leg8. Surgical treatments of distal biceps femoris tendon injury have produced promising results. Kusma et al. reviewed 8 cases of isolated avulsion of the biceps femoris from its fibular attachment; all but one case were treated operatively with good functional outcomes1. Another report of a 65-year-old man with isolated biceps femoris rupture treated with primary repair described satisfactory functional outcome, although patient functional demand was limited9. In another case series, 2 patients with complete distal biceps femoris rupture underwent surgical repair within 2 weeks of the injury, and both reported excellent results with return to preinjury level of sport6.
In our patient-athlete, the injury was debilitating and it prevented return to play at a high level, thus necessitating operative intervention. Furthermore, the patient was experiencing pain and paresthesias consistent with CPN neuritis, likely resulting from chronic inflammation and scarring. The complexity of the case was increased given the chronic nature of the injury, occurring 3 months before surgical intervention. Before surgery, the patient was informed regarding the unusual nature of the injury, lack of data to support surgical vs. nonsurgical treatments, and unpredictable outcomes. The surgical team was prepared for reconstruction with Achilles tendon allograft if an irreparable tear was identified. Surgery proceeded with primary repair, with no need for allograft repair or augmentation. The CPN was found to be intact and was released from surrounding scar tissue. Postoperatively, the patient regained full function and experienced resolution of CPN paresthesias with no functional motor deficits.
Chronic tendon lacerations or disruptions do not always behave similarly. In cases of chronic extensor mechanism disruption, reconstructive measures are often required to achieve repair and regain function10,11. In the present case, complete transection of the biceps femoris tendon was treated conservatively for 3 months and was successfully repaired without requiring soft-tissue augmentation or reconstruction. This may be due to anatomic factors in this region of the biceps femoris or differences in mechanical properties between knee flexors and extensors. Despite limited data in the literature, the patient outcome favors surgical management of patients with complete transections of the distal biceps femoris, particularly in young, athletic patients who require a high level of function. Even at 3 months, the tendon quality was amendable to repair with subsequent full return to sport at the preinjury level.
In conclusion, there is limited literature on isolated distal biceps femoris injuries in athletes. In this case report, chronic transection of the biceps femoris tendon was primarily repaired. The patient experienced full recovery of function and resolution of CPN paresthesias. He returned to his preinjury level of sport in Division 1 collegiate hockey and completed a full season after tendon repair. Despite limited data, authors support surgical treatment of this rare injury, particularly in patients who require a high level of function.
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