Plantar Plate Tenodesis for Flexible Hammer and Claw Toe Deformities

INTRODUCTION AND RATIONALE

Lesser toe deformities, encompassing hammer toes and claw toes, are among the most common pathologies encountered in foot and ankle surgery. These deformities are characterized by a complex interplay of intrinsic and extrinsic muscle imbalances, leading to hyperextension at the metatarsophalangeal (MTP) joint and flexion at the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints.

Historically, the management of these deformities relied heavily on joint-destructive procedures, such as PIP joint resection arthroplasty or arthrodesis, combined with MTP joint capsulotomies and extensor tendon lengthening. However, for strictly flexible deformities, joint-sparing techniques that restore the anatomic force vectors are highly preferred.

The Plantar Plate Tenodesis, as described by Lui et al., represents a sophisticated, biomechanically sound approach to correcting flexible hammer and claw toe deformities. By utilizing the robust plantar plate and the fibrous flexor tendon sheath as an anchor, and dynamically linking it to the extensor digitorum longus (EDL) tendon, this technique effectively creates a tenodesis that plantarflexes the MTP joint. This counteracts the deforming hyperextension forces without the need for extensive plantar dissection or joint destruction.

BIOMECHANICS AND PATHOANATOMY

To master the plantar plate tenodesis, the operating surgeon must possess a profound understanding of lesser ray biomechanics.

The Intrinsic-Extrinsic Imbalance

The stability of the lesser MTP joints relies on a delicate balance between the extrinsic musculature (EDL, extensor digitorum brevis [EDB], flexor digitorum longus [FDL], flexor digitorum brevis [FDB]) and the intrinsic musculature (lumbricals and interossei).
* Normal Function: The intrinsic muscles pass plantar to the axis of rotation of the MTP joint, acting as primary plantarflexors of the MTP joint and extensors of the IP joints.
* Pathologic State: In the presence of an intrinsic-minus foot, or when extrinsic extensors overpower the intrinsics, the MTP joint is driven into hyperextension. As the proximal phalanx dorsiflexes, the intrinsic tendons subluxate dorsal to the MTP joint's axis of rotation. Consequently, they lose their plantarflexion moment and paradoxically become MTP joint extensors, exacerbating the deformity.

The Role of the Plantar Plate

The plantar plate is a thick, fibrocartilaginous structure that serves as the primary static stabilizer against MTP joint hyperextension. Chronic MTP hyperextension leads to attenuation, elongation, or frank rupture of the plantar plate. The Lui et al. tenodesis technique capitalizes on the structural integrity of the remaining plantar plate and the adjacent fibrous flexor sheath, utilizing them as a robust distal anchor to tether the EDL, thereby converting the EDL's deforming dorsiflexion force into a corrective stabilizing force.

INDICATIONS AND CONTRAINDICATIONS

Indications

• Flexible Hammer Toe Deformity: Hyperextension at the MTP joint with flexible flexion at the PIP joint.
• Flexible Claw Toe Deformity: Hyperextension at the MTP joint with flexible flexion at both the PIP and DIP joints.
• Reducible MTP Joint Subluxation: The deformity must be fully correctable passively (e.g., a positive Kelikian push-up test demonstrating reduction of the MTP joint).
• Plantar Plate Insufficiency: Mild to moderate attenuation where the plate remains structurally contiguous enough to hold a heavy suture.

Contraindications

• Rigid Deformities: Fixed contractures of the MTP or PIP joints require osseous procedures (e.g., Weil osteotomy, PIP arthrodesis).
• Severe Degenerative Joint Disease: Arthritic changes at the MTP joint preclude soft-tissue-only joint-sparing procedures.
• Severe Plantar Plate Rupture: Complete, retracted tears of the plantar plate may require direct anatomic repair or flexor-to-extensor tendon transfer (Girdlestone-Taylor procedure) rather than a simple tenodesis.
• Compromised Soft Tissue Envelope: Poor vascularity or active infection.

PREOPERATIVE PREPARATION AND POSITIONING

Clinical Evaluation

A meticulous physical examination is paramount. The surgeon must perform the Kelikian push-up test by applying pressure to the plantar aspect of the metatarsal head. If the MTP and PIP joints reduce to a neutral, rectilinear alignment, the deformity is flexible, and the patient is an ideal candidate for plantar plate tenodesis. The MTP joint drawer test (Lachman test of the toe) should be performed to assess the degree of plantar plate attenuation and dorsal instability.

Patient Positioning

1. Position: The patient is placed in the supine position on the operating table.
2. Bump: A small bump is placed under the ipsilateral hip to internally rotate the leg to a neutral position, ensuring the foot points directly toward the ceiling.
3. Tourniquet: A calf or thigh tourniquet is applied over adequate padding to ensure a bloodless surgical field, which is critical for identifying the delicate dorsal neurovascular structures.
4. Anesthesia: The procedure can be performed under general anesthesia, regional anesthesia (popliteal block), or a local ankle block depending on patient comorbidities and surgeon preference.

SURGICAL TECHNIQUE: STEP-BY-STEP GUIDE (LUI ET AL.)

The following details the precise surgical steps for the plantar plate tenodesis, expanding upon the foundational technique described by Lui and colleagues.

Step 1: Distal Incisions and Capsular Release

The objective of this step is to gain access to the dorsal MTP joint and prepare the metatarsal neck for the tenodesis.

• Incision: Make two small longitudinal incisions—one dorsomedial and one dorsolateral—at the sides of the extensor tendon at the level of the affected (e.g., second) metatarsophalangeal joint.
• Dissection: Carefully deepen the incisions through the subcutaneous tissue.

  🔪 Surgical Warning: Neurovascular Protection

  The dorsal cutaneous branches of the superficial peroneal nerve and the proper digital arteries run in close proximity to these incisions. Blunt dissection with a small hemostat is mandatory to retract these structures medially and laterally before incising the capsule.

• Capsular Stripping: Identify the dorsal capsule of the MTP joint. Using a small periosteal elevator (e.g., a Freer elevator), strip the dorsal capsule proximally from the metatarsal neck. This release mobilizes the joint and creates a pathway for the subsequent suture passage.

Step 2: Lateral Plantar Plate Suture Passage

This is the most technically demanding step, requiring precise spatial awareness to capture the plantar plate without tethering the flexor tendons.

• Suture Selection: Utilize a heavy, absorbable monofilament suture. A Polydioxanone (PDS) No. 1 suture armed with a straight-eye needle is the gold standard for this technique.
• Needle Trajectory: Through the dorsolateral incision, pass the straight needle plantarly. The target is the lateral portion of the plantar plate and the fibrous flexor tendon sheath.
• Avoiding the Flexor Tendon:

  💡 Clinical Pearl: Needle Angulation

  To avoid inadvertently passing the suture through the substance of the flexor digitorum longus (FDL) or brevis (FDB) tendons, point the needle slightly away from the midline of the joint as it travels plantarly.

• Plantar Exit: The needle must pierce the fibrous flexor tendon sheath and exit directly through the plantar skin.
• Dynamic Joint Positioning: Crucially, the interphalangeal (PIP and DIP) joints of the toe must be held in a flexed position during the passage of the suture. Flexing the IP joints relaxes the flexor tendons, allowing them to fall away from the needle's path.
• Tethering Check: Once the suture has been passed through the plantar skin, immediately dorsiflex the toe. If the toe dorsiflexes freely without resistance, the flexor tendon has not been tethered. If resistance is felt, the suture has captured the flexor tendon; it must be removed and repassed.

Step 3: Proximal Incision and Deep Suture Routing

The suture must now be routed proximally along the metatarsal shaft to create the tenodesis effect.

• Proximal Incision: Make a 1.5 to 2.0 cm dorsal longitudinal incision centered over the midshaft of the corresponding metatarsal.
• Deep Dissection: Dissect down to the level of the extensor digitorum longus (EDL) tendon. Retract the EDL to expose the dorsal interosseous fascia.
• Hemostat Routing: Insert a curved hemostat into the proximal incision. Advance it distally along the medial side of the metatarsal shaft. The hemostat must pass deep to the flexor tendons at the plantar aspect of the metatarsal neck, eventually reaching the lateral side of the fibrous tendon sheath near the initial dorsolateral incision.

Step 4: The "Squeeze" Technique for Suture Retrieval

Because the suture currently exits the plantar skin, it must be retrieved proximally without making a large, morbid plantar incision.

• Tensioning: Hold the plantar-exiting suture firmly under tension.
• Plantar Milking: Squeeze the plantar skin firmly from distal to proximal. This "milking" action forces the plantar segment of the suture to migrate proximally within the subcutaneous fat pad.
• Retrieval: Once the suture loop is milked proximally to the level of the metatarsal neck, use the previously placed curved hemostat to grasp the suture and pull it through the deep plantar space, retrieving it out of the proximal dorsal midshaft incision.

Step 5: Medial Suture Passage and Loop Maintenance

The medial side of the plantar plate must now be secured to complete the distal anchor.

• Medial Passage: Take the other limb of the PDS suture (currently exiting the dorsolateral incision). Pass it subcutaneously from the dorsolateral incision to the dorsomedial incision, crossing dorsal to the MTP joint.
• Plantar Plate Capture: Pass the needle plantarly through the medial part of the plantar plate, utilizing the same technique as the lateral side (pointing away from the midline, IP joints flexed).
• Lateral Retrieval: Retrieve this medial suture limb along the lateral side of the metatarsal, routing it proximally to exit the proximal midshaft incision alongside the first suture limb.

  🔪 Surgical Pitfall: Loss of Suture Loop

  During this complex routing process, it is exceptionally easy to pull the suture completely through the tissue. Be absolutely certain to maintain a loop of suture distally so that tension can be applied to aid in the final retrieval and to ensure the plantar plate is securely captured.

Step 6: Tensioning and Fixation to the EDL

The final step establishes the dynamic tenodesis, correcting the deformity.

• Ankle Positioning:

  💡 Clinical Pearl: The Neutral Ankle

  Before tying the knot, the ankle must be placed in strict neutral (0 degrees of dorsiflexion/plantarflexion). Because the EDL originates proximal to the ankle joint, tensioning the suture with the ankle in equinus will result in severe hyperextension of the toe when the patient stands and brings their ankle to neutral.

• Joint Reduction: With the ankle in neutral, apply proximal tension to both limbs of the suture. Observe the MTP joint; the tension should anatomically reduce the MTP joint, bringing the proximal phalanx out of hyperextension and into a neutral alignment.
• Knot Tying: Anchor the suture to the extensor digitorum longus (EDL) tendon at the proximal incision. Tie the suture over the EDL tendon in a robust figure-of-eight configuration. This securely connects the plantar plate-flexor tendon sheath complex directly to the EDL tendon.
• Closure: Irrigate all incisions copiously. Close the skin with non-absorbable monofilament sutures (e.g., 4-0 Nylon or Prolene) in a simple interrupted fashion.

POSTOPERATIVE CARE AND REHABILITATION

The success of a plantar plate tenodesis relies as much on meticulous postoperative rehabilitation as it does on surgical execution. The goal is to maintain the tenodesis tension while preventing debilitating MTP joint stiffness.

Phase I: Immediate Postoperative (Days 1 to 14)

• Weight Bearing: Patients are allowed to weight-bear as tolerated immediately postoperatively, provided they utilize a rigid-soled postoperative sandal or shoe. The rigid sole prevents dorsiflexion of the MTP joints during the terminal stance phase of gait, protecting the tenodesis repair.
• Mobilization: Unlike traditional arthrodesis procedures that require strict immobilization, the Lui technique demands early motion.
  • Active Toe Mobilization: Patients are instructed to actively flex and extend the toes within the limits of pain starting on Postoperative Day 1.
  • Passive Plantar Mobilization: The patient or physical therapist should perform gentle passive plantarflexion of the MTP joint. Passive dorsiflexion is strictly prohibited during this phase to avoid stretching or rupturing the PDS suture repair.
• Wound Care: Sutures are typically removed at 14 days postoperatively, assuming uncomplicated wound healing.

Phase II: Intermediate Rehabilitation (Weeks 2 to 6)

• Footwear: The patient continues to use the rigid postoperative sandal.
• Physical Therapy: Active range of motion exercises are intensified. The focus remains on intrinsic muscle strengthening (e.g., towel scrunches, marble pickups) to restore the dynamic plantarflexion moment of the MTP joint.
• Edema Control: Compressive wrapping or toe sleeves (e.g., Coban) are utilized to manage the persistent digital edema ("sausage toe") that commonly follows lesser ray surgery.

Phase III: Long-Term Maintenance (Weeks 6 and Beyond)

• Transition to Normal Footwear: At 6 weeks, patients are transitioned into wide-toe-box, supportive athletic shoes. High heels and narrow, restrictive footwear are strongly discouraged to prevent recurrence.
• Return to Activity: High-impact activities and sports involving explosive push-off (which heavily load the MTP joints) are generally restricted until 10 to 12 weeks postoperatively.

COMPLICATIONS AND MANAGEMENT

While highly effective, surgeons must be prepared to manage potential complications associated with this technique.

1. Recurrence of Deformity: The most common complication. It typically occurs due to under-tensioning of the suture, tensioning the suture with the ankle in plantarflexion, or premature passive dorsiflexion during rehabilitation. Management requires revision surgery, often necessitating an osseous procedure (Weil osteotomy) if the deformity has become rigid.
2. Flexor Tendon Tethering: If the suture inadvertently captures the FDL or FDB, the patient will present with a rigid, flexed toe that cannot actively or passively extend. This requires immediate surgical release of the tethering suture.
3. MTP Joint Stiffness: Over-tensioning or inadequate postoperative mobilization can lead to a stiff, non-functional MTP joint. Aggressive physical therapy is the first line of treatment; surgical capsular release is rarely indicated but may be necessary in refractory cases.
4. Nerve Injury: Iatrogenic injury to the dorsal digital nerves during the initial incisions can result in painful neuromas or digital numbness. Careful blunt dissection and retraction are the best preventative measures.

CONCLUSION

The plantar plate tenodesis, utilizing the technique described by Lui et al., is a highly elegant, joint-sparing solution for flexible hammer and claw toe deformities. By understanding the intricate biomechanics of the intrinsic-extrinsic muscle balance and meticulously executing the deep suture routing, orthopedic surgeons can restore anatomic alignment and excellent function to the lesser rays without resorting to joint-destructive procedures. Strict adherence to the neutral-ankle tensioning rule and a disciplined postoperative mobilization protocol are the cornerstones of long-term success.