UCL Reconstruction: The Andrews Technique

Introduction to Ulnar Collateral Ligament Reconstruction

The Ulnar Collateral Ligament (UCL) is the primary static restraint to valgus stress at the elbow, particularly between 20 and 120 degrees of flexion. In overhead athletes, particularly baseball pitchers, repetitive near-failure tensile loads can lead to microtrauma, attenuation, and eventual rupture of the anterior bundle of the UCL.

The surgical management of UCL insufficiency was revolutionized by Dr. Frank Jobe in 1974. However, the classic Jobe technique involved detachment of the flexor-pronator mass, which often led to prolonged rehabilitation and flexor-pronator morbidity. The Andrews et al. technique represents a critical evolutionary modification. By utilizing a muscle-splitting approach through the flexor carpi ulnaris (FCU), this technique preserves the native flexor-pronator origin, minimizes iatrogenic trauma, and incorporates an anterior transposition of the ulnar nerve to address concomitant cubital tunnel syndrome or nerve subluxation.

This masterclass details the preoperative planning, biomechanical principles, and step-by-step surgical execution of the Andrews technique for UCL reconstruction.

Biomechanics and Surgical Anatomy

A profound understanding of medial elbow anatomy is mandatory for successful reconstruction. The UCL complex consists of three bundles:
1. Anterior Bundle: The primary restraint to valgus stress. It originates on the anteroinferior aspect of the medial epicondyle and inserts on the sublime tubercle of the proximal ulna. It is further subdivided into anterior and posterior bands, which tighten in extension and flexion, respectively.
2. Posterior Bundle: A secondary restraint that forms the floor of the cubital tunnel.
3. Transverse Bundle (Cooper’s Ligament): Originates and inserts on the ulna, contributing minimally to overall valgus stability.

💡 Clinical Pearl: Isometry

True isometry in UCL reconstruction is a theoretical ideal rather than a strict anatomical reality. The goal of the Andrews technique is to place the humeral tunnel at the exact anatomic origin of the anterior bundle (the isometric point) to ensure the graft maintains appropriate tension throughout the functional arc of motion without over-constraining the joint.

Preoperative Planning and Graft Selection

Clinical Evaluation

Patients typically present with medial elbow pain during the late cocking and early acceleration phases of throwing. Clinical examination should include the moving valgus stress test and the milking maneuver. Concomitant ulnar neuritis must be carefully documented, as its presence dictates the necessity of ulnar nerve transposition.

Imaging

• Radiographs: AP, lateral, and axillary views to assess for medial epicondyle avulsions, posteromedial osteophytes (valgus extension overload), or loose bodies.
• MRI/MRA: Magnetic Resonance Arthrography is the gold standard for evaluating partial undersurface tears of the anterior bundle.

Graft Selection Hierarchy

The presence or absence of the palmaris longus tendon must be documented preoperatively via Schaeffer’s test.
1. Ipsilateral Palmaris Longus: The gold standard due to its proximity, appropriate length (12–15 cm), and minimal harvest morbidity.
2. Contralateral Palmaris Longus: Used if the ipsilateral tendon is absent or inadequate.
3. Gracilis Tendon: An excellent alternative providing a robust, thick graft, though it requires a separate surgical field.
4. Plantaris or Fourth Toe Extensor: Viable tertiary options.

Patient Positioning and Anesthesia

1. Anesthesia: General anesthesia is typically preferred, often supplemented with a regional block (e.g., supraclavicular block) for postoperative pain control.
2. Positioning: The patient is placed supine with the operative arm extended on a radiolucent hand table.
3. Preparation: The arm is draped to expose the entire volar forearm down to the palmar crease. A sterile tourniquet is applied to the proximal arm to ensure a bloodless field during the critical dissection phases.

Surgical Technique: Step-by-Step

Phase 1: Diagnostic Arthroscopy (Optional)

If an acute, massive medial rupture is not present, a limited diagnostic arthroscopy is highly recommended.
* Utilize a standard anterolateral portal.
* Evaluate the radiocapitellar joint for chondromalacia.
* Assess the posteromedial compartment for osteophytes (valgus extension overload) and resect them if necessary.
* Perform a dynamic valgus stress test under direct visualization. Medial joint space opening of >1-2 mm confirms UCL insufficiency.

Phase 2: Incision and Superficial Dissection

• Following arthroscopy, exsanguinate the arm and inflate the tourniquet.
• Make an 8 to 10 cm longitudinal incision centered over the medial epicondyle, extending approximately 3 cm proximally and 5 cm distally.
• Nerve Protection: Meticulously identify the medial antebrachial cutaneous nerve (MABC). The MABC is highly variable, often presenting as a single large trunk with multiple arborizations crossing the operative field.

⚠️ Surgical Warning: MABC Injury

Iatrogenic injury to the MABC is a leading cause of postoperative dissatisfaction. Retract the nerve branches gently using vessel loops. Avoid excessive traction, which can lead to a painful postoperative neuroma.

Phase 3: Ulnar Nerve Management

The Andrews technique mandates anterior transposition of the ulnar nerve to prevent postoperative neuritis and to facilitate the FCU-splitting exposure.
* Elevate the skin flaps to expose the deep fascia overlying the flexor-pronator mass.
* Identify the ulnar nerve within the cubital tunnel.
* Incise the cubital tunnel retinaculum (Osborne’s fascia) to mobilize the nerve.
* Proximal Mobilization: Continue dissection proximally to release the arcade of Struthers. Excise a 2 to 3 cm portion of the medial intermuscular septum to prevent kinking or impingement of the nerve once transposed.
* Distal Mobilization: Incise the fascia of the FCU distally along the course of the nerve.
* Sacrifice the small articular branches to the elbow joint to allow adequate excursion, but meticulously preserve the motor branches innervating the FCU and flexor digitorum profundus.
* Transpose the ulnar nerve anteriorly into a secure subcutaneous pocket.

Phase 4: The Muscle-Splitting Exposure

• Follow the longitudinal split in the FCU down to the insertion of the anterior bundle of the UCL on the sublime tubercle of the ulna.
• Develop the interval between the native UCL and the overlying flexor muscle mass. Begin distally at the ulnar insertion—where the tissue plane is most distinct—and work proximally toward the medial epicondyle.
• Place small, blunt Hohmann or self-retaining retractors to retract the flexor muscles anteriorly.
• Crucial Advantage: This exposure provides full visualization of the ligament without detaching the flexor-pronator origin, preserving dynamic medial stability.

Phase 5: Ligament Evaluation and Graft Harvest

• Make a longitudinal incision in line with the fibers of the anterior bundle.
• Inspect the undersurface for detachment, attenuation, or calcification. Do not excise the native ligament. The remnants will be repaired over the graft to provide vascularity and augment the reconstruction.
• Harvesting the Graft: Make a 2-cm transverse incision at the distal wrist flexor crease. Identify the palmaris longus tendon. Use a specialized tendon stripper to harvest the graft, avoiding multiple skip incisions.
• Prepare the graft on the back table. Place a No. 1 braided nonabsorbable suture (e.g., Ethibond Excel OS-2) in a Krackow fashion at both ends of the tendon. Keep the graft wrapped in a moist saline sponge.

Phase 6: Tunnel Preparation

Precision in tunnel placement is the most critical determinant of postoperative kinematics.

Ulnar Tunnels

• Subperiosteally expose the sublime tubercle.
• Using a No. 3 burr or a 3.2 mm drill, create two converging tunnels: one anterior and one posterior to the sublime tubercle.
• Ensure a robust 2-cm bony bridge remains between the two tunnels to prevent iatrogenic fracture during tensioning.
• Connect the tunnels using a small curved curet. Pass a looped 2-0 passing suture through the ulnar tunnel.

Humeral Tunnels

• Identify the anatomic origin of the anterior bundle on the anterior half of the medial epicondyle.
• Using a No. 4 burr, create a primary longitudinal blind tunnel directed up the axis of the epicondyle to a depth of 15 mm.
• Expose the superior border of the epicondyle, just anterior to the intermuscular septum.
• Using a small dental drill or 2.0 mm bit, create two small exit tunnels separated by 5 to 10 mm, connecting into the apex of the primary 15 mm tunnel.
• Pass looped sutures through these small superior tunnels into the primary tunnel to facilitate graft docking.

Phase 7: Graft Passage and Tensioning

• Native Ligament Repair: Before passing the graft, repair the longitudinal split in the native UCL with 2-0 absorbable sutures.
• Ulnar Passage: Pass the graft through the ulnar tunnel from anterior to posterior.
• Humeral Docking: Pass the sutured limbs of the graft into the primary humeral tunnel. Shuttle the Krackow suture tails out through the two small superior exit tunnels.
• Tensioning Protocol:
  • Reduce the elbow joint.
  • Place the forearm in supination (to unlock the radiocapitellar joint) and apply a gentle varus stress (to close the medial joint space).
  • Flex and extend the elbow through a full range of motion while maintaining tension on the suture tails. This cycles the graft, eliminating viscoelastic creep.
• Measure the final length of the graft by visually estimating the portion that will be docked within the humeral tunnel. Mark the graft, trim any excess, and tie the sutures securely over the superior bony bridge of the medial epicondyle.

💡 Clinical Pearl: Tensioning

Never tension the graft with the elbow in valgus or pronation, as this will result in a lax reconstruction. The graft should be tensioned at approximately 30 to 45 degrees of flexion, where the anterior bundle is naturally taut.

Closure and Postoperative Protocol

Closure

• Ensure the ulnar nerve rests comfortably in its transposed anterior position without tension or kinking. Construct a loose fascial sling if necessary to prevent posterior subluxation.
• Close the FCU fascia loosely with absorbable sutures, ensuring no constriction of the underlying muscle or nerve.
• Close the subcutaneous tissue and skin in a standard layered fashion.
• Apply a sterile dressing and a posterior splint with the elbow immobilized at 90 degrees of flexion and neutral rotation.

Rehabilitation Protocol

Rehabilitation following the Andrews technique is phased and biologically driven, respecting the ligamentization process of the graft.

• Phase I (0–2 Weeks): Immediate postoperative immobilization in a posterior splint at 90 degrees. Wrist and hand active range of motion (AROM) is encouraged to prevent stiffness and reduce edema.
• Phase II (2–6 Weeks): Transition to a hinged elbow brace. Gradually increase ROM by 5 to 10 degrees per week. Initiate submaximal isometric exercises for the flexor-pronator mass and biceps/triceps.
• Phase III (6–12 Weeks): Discontinue the brace once full ROM is achieved. Begin isotonic strengthening, focusing on the kinetic chain, core stability, and scapular dyskinesia correction.
• Phase IV (3–4 Months): Initiate a structured interval throwing program (ITP) on flat ground.
• Phase V (9–12+ Months): Progression to throwing off the mound. Return to competitive play is typically achieved between 12 and 18 months postoperatively, contingent upon the restoration of dynamic stability and absence of pain.

Complications and Pitfalls

While the Andrews technique boasts a high success rate for return to sport, surgeons must be vigilant regarding potential complications:
1. Ulnar Neuropathy: The most common postoperative complication. Meticulous handling of the nerve, preservation of its vascular leash, and adequate excision of the intermuscular septum are paramount.
2. MABC Neuroma: Results from aggressive retraction or transection of the medial antebrachial cutaneous nerve.
3. Bone Bridge Fracture: Occurs if the ulnar tunnels are placed too close together. Always maintain a minimum 2-cm bridge.
4. Loss of Extension: Often due to over-tensioning the graft or prolonged postoperative immobilization. Early, controlled ROM in the hinged brace mitigates this risk.

By adhering to the strict biomechanical principles and meticulous tissue-handling techniques outlined in this guide, the orthopedic surgeon can consistently achieve stable, durable reconstructions, allowing elite overhead athletes to return to their pre-injury level of performance.