What is the detailed step‑by‑step surgical technique for tendon‑transfer reconstruction of a first metacarpophalangeal joint ligament injury?

Surgical Technique for Tendon Transfer Reconstruction of First MCP Joint Ligament Injury

Critical Pre-Operative Assessment

Before proceeding with tendon transfer, you must first determine whether acute repair or reconstruction is indicated based on timing and injury pattern. 1, 2

Diagnostic Confirmation Required

• Obtain minimum 3-view radiographs (PA, lateral, and oblique) to exclude bony avulsion fractures involving ≥1/3 of the articular surface, which would require different surgical management 3
• Perform stress testing with the MCP joint in both full extension and 30° flexion—complete tear is diagnosed when angulation exceeds 30-35° or shows >15° difference compared to the contralateral thumb 2
• Confirm absence of a firm endpoint on stress examination, which indicates complete ligamentous disruption requiring surgical intervention 2
• Consider MRI without IV contrast if radiographs are negative but clinical suspicion remains high, as it can simultaneously demonstrate ligamentous injuries and guide surgical planning 4, 3

Timing-Based Surgical Decision Algorithm

• If injury is <4 weeks old: Primary ligament repair is preferred over reconstruction 1
• If injury is >4 weeks old (chronic instability): Ligament reconstruction with tendon graft becomes the treatment of choice 1, 2
• If Stener lesion is present: Surgical intervention is mandatory regardless of timing, as the adductor aponeurosis interposes between the torn ligament and its insertion, preventing healing 1

Step-by-Step Tendon Transfer Reconstruction Technique

For chronic first MCP joint collateral ligament instability (>4 weeks post-injury), static triangular ligament reconstruction using a free tendon graft with proximal apex configuration is the recommended approach. 5

Surgical Preparation

• Position the patient supine with the hand on a radiolucent hand table under regional or general anesthesia 5
• Apply a pneumatic tourniquet to the upper arm for bloodless field 5
• Harvest palmaris longus tendon graft from the ipsilateral forearm (or use plantaris or toe extensor if palmaris is absent) 2, 5

Exposure and Ligament Assessment

• Make a curved incision centered over the affected collateral ligament (ulnar or radial side of the thumb MCP joint) 2
• Identify and protect the dorsal sensory branches of the radial nerve during dissection 2
• Incise the adductor aponeurosis (ulnar side) or abductor expansion (radial side) longitudinally to expose the joint capsule 2
• Excise the remnant scarred ligament tissue and identify the anatomic insertion points on the metacarpal head and proximal phalanx base 2, 5

Bone Tunnel Creation

• Drill a 2.5-3.0 mm bone tunnel through the metacarpal head from the origin point of the collateral ligament, exiting dorsally 5
• Create a second bone tunnel through the base of the proximal phalanx at the insertion point of the collateral ligament 5
• Configure the tunnels to create a triangular reconstruction with the apex positioned proximally on the metacarpal, which provides optimal biomechanical stability 5

Tendon Graft Passage and Fixation

• Pass one end of the harvested tendon graft through the metacarpal tunnel from dorsal to volar 5
• Route the graft through the proximal phalangeal tunnel to create the triangular configuration 5
• Tension the graft with the thumb MCP joint positioned in 20-30° of flexion and neutral rotation to restore proper joint mechanics 2, 5
• Secure the graft ends using suture anchors, interference screws, or suture-through-bone technique with the joint held in the appropriate position 2, 5
• Verify restoration of joint stability by performing intraoperative stress testing—angulation should be reduced to within 10° of the contralateral thumb 5

Closure and Post-Operative Protocol

• Repair the adductor aponeurosis or abductor expansion over the reconstruction 2
• Close skin in layers and apply a thumb spica splint maintaining the MCP joint in slight flexion 2, 5
• Immobilize for 4-6 weeks to allow graft incorporation 2, 5
• Begin active range of motion exercises of the interphalangeal joint immediately while keeping the MCP joint splinted to prevent stiffness 6
• After 4-6 weeks, initiate protected MCP joint motion with buddy taping and progressive strengthening 2, 5

Alternative Reconstruction Options

• Modified Brand tendon transfer may be considered as an adjunctive procedure when there is associated extensor lag of the interphalangeal joints following crushing-penetrating injuries, typically performed at 4-5 months after initial MCP joint stabilization 7
• MCP joint arthrodesis is reserved for cases with severe arthritic changes or failed reconstruction attempts where pain and instability persist 4, 2

Expected Outcomes and Complications

• Triangular tendon graft reconstruction reduces stress testing angulation by approximately 43° compared to pre-operative values and achieves stability within 6.5° of the uninjured hand 5
• Expect 10-15° loss of MCP flexion and 8-10° loss of extension compared to the contralateral thumb, which is functionally well-tolerated 5
• Grip and key-pinch strength return to near-normal levels, and pre-operative pain typically resolves to occasional discomfort 5
• All patients in reported series returned to work or daily activities with subjective sense of stability maintained at long-term follow-up 5

Critical Pitfalls to Avoid

• Do not attempt manual reduction before obtaining radiographs—imaging must be performed first to exclude fractures requiring different surgical management 3
• Failure to identify a Stener lesion leads to failed conservative treatment, as the interposed adductor aponeurosis prevents ligament healing 1
• Inadequate tensioning of the graft results in persistent instability, while over-tensioning causes stiffness and loss of motion 2, 5
• Removing splints during the initial 4-6 week healing phase can compromise graft incorporation and restart the healing timeline 6
• Delaying surgery beyond 4 weeks in complete tears leads to ligament retraction and scarring, making reconstruction more technically demanding than acute repair 1, 2