Two-Incision Technique for Distal Biceps Tendon Repair: The Boyd and Anderson Method

Introduction to Distal Biceps Tendon Ruptures

Rupture of the distal biceps brachii tendon is a relatively uncommon but highly debilitating injury, predominantly affecting the dominant arm of middle-aged males during an unexpected eccentric contraction. The biceps brachii is the primary supinator of the forearm and a secondary flexor of the elbow. Failure to anatomically restore the tendon to its native footprint on the radial tuberosity results in a permanent 40% to 50% deficit in supination strength and a 20% to 30% deficit in flexion strength, alongside profound losses in endurance.

Historically, the single-incision anterior extensile approach (the Henry approach) was utilized for repair. However, this approach required deep, vigorous retraction of the radial nerve and its branches, leading to an unacceptably high incidence of posterior interosseous nerve (PIN) palsy. To circumvent this devastating complication, Boyd and Anderson developed the Two-Incision Technique. By utilizing a limited anterior incision for tendon retrieval and a separate posterolateral incision for tuberosity preparation and fixation, surgeons can achieve anatomic, isometric reattachment while drastically reducing the risk of neurologic injury.

This masterclass provides an exhaustive, step-by-step guide to the modified Boyd and Anderson two-incision technique, focusing on transosseous "trapdoor" fixation, neurovascular protection, and evidence-based postoperative rehabilitation.

Surgical Anatomy and Biomechanics

A profound understanding of the regional anatomy is non-negotiable for the safe execution of the two-incision technique.

The Native Footprint

The distal biceps tendon does not insert centrally on the radius; rather, it inserts on the ulnar aspect of the radial tuberosity. This eccentric insertion acts as a cam, maximizing the moment arm for supination. Reattaching the tendon too anteriorly on the radius will severely compromise supination torque. The two-incision technique naturally guides the surgeon to the ulnar aspect of the tuberosity, ensuring an anatomic and biomechanically optimized repair.

Neurovascular Considerations

• Posterior Interosseous Nerve (PIN): The PIN branches from the radial nerve and courses through the supinator muscle, wrapping around the radial neck. Pronation of the forearm is the single most critical maneuver during the posterolateral approach, as it rotates the radial tuberosity posteriorly into the surgical field while simultaneously pulling the PIN anteriorly and safely away from the retractor blades.
• Lateral Antebrachial Cutaneous Nerve (LABCN): This terminal sensory branch of the musculocutaneous nerve exits lateral to the biceps tendon in the distal arm. It is highly susceptible to traction injury during the anterior approach.
• Brachial Artery and Median Nerve: Located medial to the biceps tendon, these structures are protected by maintaining dissection strictly lateral to the lacertus fibrosus (bicipital aponeurosis) unless the aponeurosis requires division for tendon retrieval.

💡 Clinical Pearl: The Interosseous Membrane

The pathway between the anterior and posterior incisions traverses the interosseous membrane. The native tendon tunnel must be utilized. Creating new or multiple pathways through the interosseous membrane significantly increases the risk of heterotopic ossification (HO) and subsequent radioulnar synostosis.

Preoperative Planning and Patient Positioning

Indications

• Acute, complete ruptures of the distal biceps tendon in active patients.
• Partial ruptures that have failed conservative management and demonstrate significant weakness or pain.
• Chronic ruptures (though these may require allograft reconstruction if the tendon has severely retracted and degenerated).

Positioning and Setup

1. Anesthesia: General anesthesia is typically preferred, often supplemented with a regional supraclavicular or axillary block for postoperative pain control.
2. Positioning: The patient is placed in the supine position. The operative extremity is positioned on a radiolucent hand table.
3. Tourniquet: A non-sterile pneumatic tourniquet is applied high on the brachium. Exsanguination is performed with an Esmarch bandage, and the tourniquet is inflated to 250 mm Hg (or 100 mm Hg above systolic blood pressure).
4. Preparation: The arm is prepped and draped free to allow full, unhindered range of motion (flexion, extension, pronation, and supination) during the procedure.

Surgical Technique: Step-by-Step

The following protocol details the classic Boyd and Anderson approach utilizing a transosseous bone bridge and trapdoor technique.

Phase 1: The Anterior Approach and Tendon Retrieval

1. Incision: Make a 2-cm transverse anterior incision in the antecubital crease, directly over the palpable defect or the anticipated path of the retracted biceps tendon. A transverse incision offers superior cosmetic results compared to a longitudinal incision and reduces the risk of crossing flexion creases.
2. Superficial Dissection: Carefully incise the subcutaneous tissues. Identify and meticulously retract the lateral antebrachial cutaneous nerve (LABCN) and superficial venous structures (e.g., cephalic vein).
3. Deep Fascia: Open the deep fascia. If the lacertus fibrosus is intact, it may need to be partially released to mobilize the tendon.
4. Tendon Identification: Identify the retracted distal biceps tendon via palpation. In acute cases, a hematoma will guide you to the stump. Grasp the tendon stump with an Allis clamp or a heavy hemostat and deliver it into the anterior wound.
5. Debridement: Excise the degenerated, frayed distal tip of the tendon until healthy, organized collagen bundles are encountered.

Phase 2: Tendon Preparation

Robust suture fixation within the tendon is critical to withstand the forces of early postoperative rehabilitation.

1. Suture Selection: Utilize a heavy, non-absorbable, braided suture (e.g., #2 or #5 FiberWire, Ethibond, or similar ultra-high-molecular-weight polyethylene suture).
2. Krakow Technique: Place a running, locking Krakow stitch along the distal 2 to 3 cm of the tendon.

⚠️ Surgical Warning: Suture Spacing

It is imperative to keep each locking throw in close proximity to the previous throw. Widely spaced throws will cause the tendon to kink, accordion, or form a bunched, bulbous end. A bunched tendon will prohibit smooth passage through the interosseous space and prevent the tendon from seating flush into the osseous "trapdoor" created in the radial tuberosity.

Phase 3: Establishing the Transosseous Pathway

1. Locating the Native Tunnel: Insert a blunt instrument or a gloved finger into the anterior wound and follow the native paratenon sheath down to the radial tuberosity.
2. Passing the Instrument: With the forearm in full supination, pass a long, curved hemostat or a blunt passing instrument from the anterior incision, along the native tendon path, through the interosseous space, and tent the skin posterolaterally over the radial aspect of the ulnar border.

🛑 Surgical Pitfall: Heterotopic Ossification

You must locate the original tunnel through the interosseous membrane. Avoid making multiple passes or creating false passages through the membrane. Excessive trauma to the interosseous membrane and surrounding musculature is the primary catalyst for heterotopic ossification and devastating radioulnar synostosis.

Phase 4: The Posterolateral Approach

1. Incision: Make a longer, 6- to 8-cm posterolateral incision over the radial aspect of the ulnar border, guided by the tenting of the blunt instrument passed from anteriorly.
2. Deep Dissection: Deepen the posterolateral incision through the subcutaneous tissue. Identify the interval between the extensor carpi ulnaris (ECU) and the anconeus.
3. Anconeus Elevation: Identify the anconeus muscle and sharply dissect it off the ulna, reflecting it radially.
4. Nerve Protection: Pronate the arm fully. This is the most critical step of the posterior approach. Pronation rotates the radial tuberosity into the surgical field and wraps the posterior interosseous nerve (PIN) anteriorly, safely away from the retractor blades and the tuberosity.
5. Exposing the Tuberosity: Subperiosteally elevate the supinator muscle off the radial tuberosity to expose the native biceps footprint.

Phase 5: Tuberosity Preparation (The "Trapdoor")

1. Creating the Trough: Use a small, ¼-inch curved osteotome or a high-speed burr to decorticate the native footprint and create a trough or "trapdoor" in the ulnar aspect of the radial tuberosity. The trough should be appropriately sized to accommodate the prepared tendon stump (typically 8-10 mm wide and 15-20 mm long).
2. Drill Holes: Drill two small holes in the dorsal aspect of the trough (the cortex opposite the trapdoor).
3. The Bone Bridge: Ensure you leave a robust, 10-mm bone bridge between the two drill holes. A bridge narrower than 10 mm is at high risk of fracture during knot tying or early postoperative mobilization, which would result in catastrophic failure of the repair.

Phase 6: Tendon Passage and Fixation

1. Tendon Delivery: Attach the suture limbs from the prepared tendon to the curved hemostat that was passed from anterior to posterior. Carefully pull the hemostat posteriorly, delivering the sutures and the tendon through the native interosseous tunnel and into the posterolateral wound.
2. Suture Passage: Use a suture passer (or a Hewson suture passer) to retrieve the first set of suture limbs. Pass them into the trough and out through the first drill hole.
3. Second Suture Passage: Pass the second set of suture limbs into the trough and out through the second drill hole.
4. Seating the Tendon: While maintaining tension on the sutures, carefully guide the tendon stump directly into the osseous trough. Ensure the tendon is fully seated within the cancellous bone bed to promote optimal tendon-to-bone healing.
5. Tying the Knot: With the elbow flexed to approximately 60 to 90 degrees and the forearm in full supination (to maximize the excursion of the tendon and ensure isometric tensioning), tie the sutures securely over the 10-mm bone bridge. Cut the suture ends flush.

Phase 7: Closure and Hemostasis

1. Anterior Closure: Thoroughly irrigate the anterior wound. Close the anterior incision in layers while keeping the elbow flexed at about 60 degrees to minimize tension on the repair.
2. Tourniquet Release: Deflate the tourniquet prior to posterior closure. Obtain meticulous hemostasis using electrocautery. Hematoma formation in the posterior wound is a known risk factor for heterotopic ossification.
3. Posterior Closure: Allow the anconeus to fall back into place. Close the deep fascia, subcutaneous tissue, and skin of the posterolateral incision in a standard layered fashion.

Postoperative Care and Rehabilitation Protocol

The postoperative rehabilitation protocol must balance the need for early motion to prevent stiffness with the biological requirement for tendon-to-bone healing. The following timeline represents a strictly evidence-based, phased approach.

Phase I: Immediate Postoperative (Weeks 0 - 2)

• Immobilization: In the operating room, apply a well-padded posterior plaster splint. The elbow must be immobilized in 110 degrees of flexion with the forearm in moderate supination. This position maximally offloads tension from the repaired tendon.
• Restrictions: Absolute non-weight bearing. No active elbow flexion or active forearm supination.
• Edema Control: Strict elevation and cryotherapy.

Phase II: Early Protection and Passive Motion (Weeks 2 - 4)

• Splint Removal: At the 2-week postoperative mark, remove the posterior splint and all skin sutures.
• Bracing: Transition the patient to a hinged elbow brace. The brace is typically locked at 90 degrees of flexion during rest.
• Range of Motion (ROM):
• Passive Flexion: Allowed and encouraged to prevent capsular contracture.
• Active Extension: Allowed within the limits of the brace. The brace hinge is gradually opened to allow progression of extension by 15 to 20 degrees per week.
• Restrictions: Continue to prohibit active flexion and active supination.

Phase III: Intermediate Motion (Weeks 4 - 6)

• Forearm Rotation: Initiate active-assisted and passive supination and pronation range-of-motion exercises.
• Extension Progression: Continue advancing the hinged brace extension block by 15 to 20 degrees weekly until full extension is achieved.
• Discontinuation of Brace: The hinged brace is typically discontinued at the end of week 6, provided the patient has achieved functional, pain-free motion.

Phase IV: Strengthening and Normalization (Weeks 6 - 8)

• ROM Goals: By 6 to 8 weeks, the patient should demonstrate a full, symmetric range of motion in both the flexion/extension and pronation/supination arcs.
• Strengthening: Initiate light, progressive isotonic strengthening. Begin with 1- to 2-pound weights for flexion and supination, focusing on high-repetition, low-resistance exercises to stimulate collagen remodeling without overloading the healing enthesis.

Phase V: Return to Play/Heavy Labor (Weeks 12 - 16)

• Advanced Strengthening: Progress to heavy eccentric loading and plyometric exercises.
• Clearance: Return to full, unrestricted activities—including heavy manual labor, weightlifting, and contact sports—should be strictly delayed until 12 to 16 weeks postoperatively. Clearance is contingent upon the restoration of symmetric strength, absence of pain, and full dynamic stability of the elbow joint.

Complications and Surgical Pitfalls

While the two-incision technique significantly reduces the risk of radial nerve injury, it introduces its own unique set of potential complications that the orthopedic surgeon must actively mitigate.

Radioulnar Synostosis

The most feared complication of the two-incision technique is the development of heterotopic ossification (HO) leading to a proximal radioulnar synostosis. This results in a complete, irreversible loss of forearm rotation.
- Prevention: Minimize trauma to the interosseous membrane. Do not make multiple passes with the passing instrument. Thoroughly irrigate the posterior wound to remove all bone dust generated during the creation of the tuberosity trough. Obtain meticulous hemostasis before closure. Some surgeons advocate for a short postoperative course of Indomethacin (75 mg sustained-release daily for 3-6 weeks) as prophylaxis in high-risk patients.

Posterior Interosseous Nerve (PIN) Injury

Although the two-incision technique was designed to protect the PIN, the nerve remains vulnerable during the posterolateral approach if the anatomy is distorted or if the surgeon fails to position the arm correctly.
- Prevention: The forearm must be fully pronated during the deep dissection of the posterolateral approach and during the preparation of the radial tuberosity. Retractors must be placed carefully on the bone, avoiding deep, blind plunging into the supinator muscle belly.

Re-Rupture

Failure of the repair typically occurs at the suture-tendon interface or due to fracture of the bone bridge.
- Prevention: Ensure the Krakow locking throws are placed closely together to prevent tendon bunching and suture pull-through. Maintain a minimum 10-mm bone bridge between the dorsal drill holes. Strictly adhere to the postoperative rehabilitation protocol, avoiding premature active flexion or heavy lifting.

Conclusion

The Boyd and Anderson two-incision technique remains a gold-standard approach for the anatomic repair of distal biceps tendon ruptures. By utilizing a transosseous trapdoor fixation method, surgeons can achieve a robust, biomechanically sound repair that restores native supination and flexion power. Meticulous attention to surgical anatomy—specifically the protection of the PIN via forearm pronation and the preservation of the interosseous membrane to prevent synostosis—is paramount. When combined with a disciplined, phased postoperative rehabilitation protocol, this technique yields excellent, reproducible clinical outcomes, allowing patients to return to high-demand physical activities with confidence.