Pediatric Flexor Carpi Radialis (FCR) Injuries: Clinical Diagnosis & Initial Imaging
Key Takeaway
Diagnosing pediatric Flexor Carpi Radialis (FCR) injuries requires a high index of suspicion. Patients present with volar wrist pain, weakness in wrist flexion/radial deviation, and localized swelling after trauma, often FOOSH. Clinical examination reveals exquisite tenderness over the FCR tendon and inability to resist wrist flexion. Initial plain radiographs rule out fractures, guiding further soft tissue imaging.
You are reviewing a 13-year-old male who presented with radial-sided volar wrist pain following a skateboarding fall. Initial radiographs of the wrist are unremarkable. The patient has visible swelling and an inability to actively flex the wrist or radially deviate against resistance. Describe your immediate clinical examination steps to confirm the suspected diagnosis.
Candidate: I would perform a focused examination of the FCR tendon. I would palpate along the tendon's course from the medial epicondyle to the base of the second metacarpal, looking for a focal gap or tenderness. I would also ask the patient to perform resisted wrist flexion and radial deviation while observing the tendon excursion. A loss of tendon prominence and functional weakness would suggest an FCR rupture.
Focusing exclusively on bone pathology (e.g., repeating "I'll look for scaphoid or radius fractures") without mentioning the specific provocative tests for the FCR. Failing to mention a neurovascular exam is a major error, as median nerve contusion is a known associated injury.
A structured approach is required: 1) Inspection: Note swelling/ecchymosis and look for a 'bulge' indicating proximal retraction. 2) Palpation: Identify focal tenderness along the FCR course and attempt to palpate the 'gap'. 3) Functional Testing: Test resisted wrist flexion and radial deviation; compare to the contralateral side. 4) Neurovascular Exam: Crucially assess the median nerve (sensation and thenar motor function) and radial artery patency, as these are vulnerable given their proximity to the FCR.
The ultrasound confirms a complete FCR tendon rupture with 4.5 cm of retraction. You have ordered an MRI. What are you specifically looking for on the MRI that would influence your surgical planning?
Candidate: I am using the MRI to confirm the location of the proximal stump to ensure I plan the correct incision length. I am also checking for associated carpal ligament injuries, the status of the median nerve, and any associated bony avulsion fragments that might require fixation.
Ignoring the "degree of retraction." Failing to mention that if the retraction is extreme or the tissue is poor, the plan might need to shift from simple primary repair to potential tendon grafting or transfer. Candidates often forget to mention ruling out ligamentous or articular cartilage damage.
I would structure the review of the MRI by: 1) Tendon Integrity: Quantify retraction distance to determine if a primary repair is feasible or if a graft/lengthening is needed. 2) Associated Soft Tissue: Check for carpal ligamentous injuries (e.g., SL/LT complex) and TFCC involvement. 3) Neural Status: Evaluate the median nerve for signal change, signaling neuropraxia or contusion, which would necessitate careful intra-operative handling or decompression. 4) Bone: Identify any occult avulsion fragments at the base of the 2nd/3rd metacarpal or trapezium.
During the surgery, you have successfully retrieved the retracted proximal tendon. You are preparing to perform the repair. Which technique would you employ, and why is this appropriate for this specific patient?
Candidate: I would use a modified Kessler core suture using a non-absorbable braided suture like FiberWire, reinforced with a running epitendinous suture. This provides the necessary tensile strength to resist gapping during early controlled mobilization, which is vital for long-term function in an active adolescent.
Suggesting a simple end-to-end suture without mentioning a core-suture technique. Failing to explain the importance of the epitendinous suture in minimizing adhesions—a common source of secondary complications in tendon repair.
I would select a 4-strand modified Kessler core repair for its superior biomechanical profile, as it resists gapping under cyclic loading. This must be augmented with an epitendinous running suture (e.g., Pennington) to smooth the repair site, reduce the profile, and minimize the risk of peritendinous adhesions. In an adolescent, ensuring a robust construct is critical to allow for safe, early controlled passive motion, which is the cornerstone of preventing post-operative stiffness.
