Neglected Zone II Flexor Tendon Injury at Three Weeks
A 24-year-old carpenter lacerated the volar aspect of his left index finger at the base 3 weeks ago. A rural clinic irrigated and sutured the skin; no tendon repair was attempted. He now cannot flex the PIP or DIP joint, and the digit is held in extension. Sensation over the ulnar aspect of the digit is diminished (2-point discrimination 12 mm). The skin wound is healed but tethered, and there is a palpable gap in the sheath at the A2 pulley. PIP and DIP passive range of motion is full, and the finger is supple. X-ray shows no fracture. Ultrasound suggests retraction of the FDP tendon with a 3 cm gap; the FDS is clinically intact. The patient works as a carpenter and needs grip strength. He is otherwise healthy and a non-smoker. The clinic asks whether primary repair is still possible.
1. What are the reconstructive options, and which would you choose? Justify your decision.
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At 3 weeks, the tendon ends are retracted and a 3 cm gap cannot be closed primarily without excessive tension. Primary repair would risk rupture or a stiff finger. The realistic options are a single-stage free tendon graft and a two-stage reconstruction with a silicone rod followed by a graft.
Favourable factors here are full passive range of motion, supple joints, no infection, and a healed wound. Unfavourable factors are the tethered skin and the palpable A2 sheath defect. My preference is a single-stage palmaris longus graft through a generous Brunner incision, excising scar and reconstructing the A2 pulley with a slip of FDS or extensor retinaculum. If the bed proves diffusely scarred or the pulleys are unreconstructable, I would place a silicone rod and perform a delayed graft in 3–6 months. A single-stage reconstruction gives earlier return to work for a carpenter if the bed is adequate.
I would also repair the digital nerve if a healthy distal stump can be found, and release the tethered scar. The patient should understand that grip strength and full flexion may not return to normal.
2. Describe the technical steps of a single-stage tendon graft, including pulley management and tensioning.
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Use a Brunner zigzag incision with extensions to expose the entire zone II course. Preserve and reconstruct the pulley system: retain A2 and A4, and reconstruct a destroyed A2 with a slip of FDS or a strip of extensor retinaculum passed around the phalanx. Excise scar until the bed is supple, but avoid stripping the entire tendon bed.
Harvest palmaris longus through a small transverse wrist incision, using a tendon stripper. Pass the graft through the reconstructed pulley and the intact sheath. Repair the distal juncture first with a 4-strand core suture and an epitendinous running suture; then tension the graft with the wrist in neutral and the finger in slight flexion, so that the finger rests in a slightly more flexed posture than the adjacent digit. Secure the proximal juncture with a core suture. Do not close the sheath tightly; close only skin. Repair the digital nerve with epineurial sutures under loupe magnification.
Check that the finger can be passively extended to the same degree as before, and that there is no bowstringing. Apply a dorsal blocking splint with the wrist in 20–30 degrees of flexion and the MCP joints in 60–70 degrees of flexion.
3. Outline the rehabilitation plan and the expected complications.
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For a tendon graft, protected early motion starts within 3–5 days under hand-therapy supervision. Use a dorsal blocking splint and a programme of passive flexion with active extension, or place-and-hold exercises, depending on the repair strength. Avoid active flexion against resistance for 6 weeks. Gradual active flexion is introduced at 4–6 weeks, and resisted gripping at 8–12 weeks. A carpenter should expect 8–12 weeks before returning to full duties, and may need modified work earlier.
The main risks are adhesion formation, rupture, and stiffness. Adhesions are more likely after a delayed reconstruction and a scarred bed; tenolysis may be needed at 3–6 months if motion plateaus. Rupture usually follows early resisted flexion, so therapy must be supervised. Complex regional pain syndrome and cold intolerance can occur after digital nerve injury. I would counsel him that full DIP flexion and normal grip strength are not guaranteed, and document baseline measurements so that progress can be judged objectively.