Masterclass: Precision Tibial Sesamoidectomy for Refractory Hallux Pain

Welcome, fellows, to the operating theater. Today, we're tackling a procedure that, while seemingly small, demands immense precision and a profound understanding of forefoot biomechanics: the Tibial Sesamoidectomy. This isn't just about removing a bone; it's about restoring function, alleviating chronic pain, and preserving the delicate balance of the first ray.

Understanding the Sesamoid Complex: Anatomy and Biomechanics

Before we make any incision, let's refresh our understanding of the critical anatomy and biomechanics at play. The sesamoids are truly fascinating structures, integral to the function of the great toe.

• Location and Function: We have two sesamoid bones, medial (tibial) and lateral (fibular), nestled plantar to the head of the first metatarsal. They are embedded within the conjoined tendon of the flexor hallucis brevis (FHB) muscle. Biomechanically, they act as a crucial fulcrum, enhancing the mechanical advantage of the FHB tendon during metatarsophalangeal (MTP) joint plantarflexion. Think of them as a pulley system.
• Weight-Bearing and Stress: During the stance phase of gait, particularly during toe-off, these sesamoids bear a significant amount of stress. The tibial sesamoid, being slightly larger, more distal, and located medially, typically absorbs more of this stress compared to its fibular counterpart. This explains the increased incidence of injuries we see in the tibial sesamoid.
• Articular Relationships: The dorsal surfaces of the sesamoids articulate with specific facets on the plantar aspect of the first metatarsal head, separated by a bony crista. This articulation is critical for smooth gliding during toe movement. The sesamoids also protect the flexor hallucis longus (FHL) tendon, which passes between them.
• Ligamentous Support: They are held together by the intersesamoid ligament and are firmly integrated into the plantar plate complex, providing stability to the MTP joint.
• Ossification and Variations: Ossification typically occurs from multiple centers between ages seven and ten. This developmental process accounts for the relatively common finding of bipartite (two segments) or tripartite (three segments) sesamoids, with the tibial sesamoid being bipartite in about 19% of the population and bilateral in 25% of patients. This anatomical variation often complicates diagnosis, as differentiating a congenital bipartite sesamoid from an acute fracture can be challenging.

Figure 1A: Medial view illustrating the relationship of the abductor hallucis brevis and the plantar cutaneous nerve to the sesamoid complex.

Figure 1B: Detailed view of the medial anatomy, highlighting the tendinous slips to the sesamoid from the abductor hallucis muscle and the surrounding ligamentous structures.

Figure 3: Anteroposterior view of a foot demonstrating a classic bipartite tibial sesamoid.

Figure 3: Another AP view of a bipartite sesamoid.

Pathogenesis and Clinical Presentation

Patients presenting with sesamoid pain often have a history of either a single acute traumatic event or, more commonly, repetitive microtrauma.

• Acute Injuries: These often mimic a "turf toe" injury, involving acute hyperextension of the hallux MTP joint, or a direct contusion to the forefoot. Such mechanisms can lead to a frank fracture or an injury to a pre-existing bipartite sesamoid, disrupting its synchondrosis.
• Chronic Injuries: More frequently, patients cannot recall a specific incident but describe a gradual onset of activity-related discomfort. This is typical for repetitive stress injuries, osteochondritis dissecans, and arthrosis.
• Symptoms: Pain is typically localized to the plantar aspect of the great toe, exacerbated by weight-bearing and activities requiring hallux dorsiflexion, such as running, jumping, toe-raising, or climbing stairs. Patients often prefer cushioned footwear. An antalgic gait with external rotation and medial off-loading is common.
• Neuritic Pain: Compression of the plantar medial cutaneous nerve, which lies directly beneath the tibial sesamoid, can also cause neuritic pain, presenting as paresthesia distally.

Physical Examination Findings

A thorough physical exam is paramount.

• Inspection: Look for subtle swelling over the plantar aspect of the hallux MTP joint.
• Palpation: Direct palpation under the tibial sesamoid will elicit tenderness. This pain is often exacerbated with forced dorsiflexion of the hallux MTP joint. Perform a Tinel sign directly over the tibial sesamoid; a positive sign (paresthesia distally) suggests plantar medial cutaneous nerve compression.
• Range of Motion (ROM): Assess dorsiflexion and plantarflexion of the MTP joint, stabilizing the metatarsal head with one hand and manipulating the proximal phalanx with the other. Note any loss of ROM or asymmetry compared to the contralateral foot.
• Strength: Assess plantarflexion strength against resistance or with a single-limb toe raise. Pain often limits these activities.
• Drawer Test: For acute injuries or suspected bipartite sesamoid disruption, perform a drawer test of the hallux MTP joint by grasping the proximal phalanx and metatarsal head and applying dorsal-to-plantar stress. Laxity can indicate a fracture or synchondrosis disruption.
• Hallux Alignment: Crucially, assess for pre-existing hallux valgus or a cavus foot. These conditions significantly alter biomechanics and may necessitate concomitant procedures to prevent progressive deformity after sesamoidectomy.

Imaging and Diagnostic Studies

Appropriate imaging is essential for accurate diagnosis and surgical planning.

• Routine Radiographs: Obtain standing anteroposterior (AP), lateral, oblique, and axial sesamoid views. These views are often diagnostic for arthrosis, osteochondritis dissecans, or significant fragmentation.
  

  
  
  

Figure 4: A sesamoid view demonstrating significant fragmentation of the tibial sesamoid, indicative of chronic pathology.

Differential Diagnosis

It's vital to consider a broad differential for forefoot pain:
* Fractured sesamoid
* Infection (rare)
* Sesamoid-metatarsal or MTP arthrosis/chondromalacia
* Bursitis
* Flexor tendinosis (FHL or FHB)
* Osteochondritis dissecans
* Intractable plantar keratosis (IPK)
* Nerve compression (plantar medial cutaneous nerve)
* Bipartite or tripartite sesamoid injury
* Turf toe injury

Nonoperative Management

Most sesamoid injuries will respond to conservative treatment, which should always be exhausted before considering surgery.

• Rest and Immobilization: Initial treatment typically involves 2 to 4 weeks of rest or immobilization, followed by 4 to 6 weeks of protected weight-bearing in an orthotic, walker boot, or cast.
• Footwear Modification:
  • Hard-soled shoes decrease dorsiflexion stresses across the MTP joint.
  • Negative-heel shoes reduce forefoot loading.
  • Orthoses like a turf-toe plate or a dancer's pad with medial longitudinal arch support can significantly decrease stress.
  • A Morton extension can also be beneficial by offloading the MTP joint.
    

    
    
    

Figure 7: Examples of nonoperative aids: A. Dancer's pad with sesamoid cut-out. B. Morton extension in an orthotic.
* Activity Modification: Taping the MTP joint to prevent dorsiflexion can allow continued participation in some athletic activities.
* Pharmacotherapy: Nonsteroidal anti-inflammatory drugs (NSAIDs) can augment treatment.
* Injections: Judicious use of steroid injections for chronic sesamoiditis can provide temporary relief, but repeated injections carry risks of tissue atrophy and infection.

Surgical Management: Indications and Contraindications

Indications:
The primary indication for operative intervention is persistent, debilitating pain under the tibial sesamoid that has failed to respond to a comprehensive course of conservative treatment (typically 3 to 12 months). We must also carefully evaluate for concomitant hallux MTP malalignment, a cavus foot deformity, or MTP joint stiffness, as these may require additional procedures to ensure a successful outcome.

Contraindications:
* Absolute: Previous excision of the fibular sesamoid or congenital absence of the fibular sesamoid. Removing both sesamoids can lead to significant hallux instability, cock-up deformity, and transfer metatarsalgia.
* Relative: A history of peripheral vascular disease, significant soft tissue or wound healing problems, diabetes mellitus, and smoking. These conditions increase the risk of complications and require thorough patient counseling and optimization before surgery.

Preoperative Planning: Beyond the Sesamoid

This is where your clinical judgment truly shines, fellows.

• Hallux Alignment: The initial assessment of hallux alignment is paramount. If a patient's hallux alignment would warrant surgical realignment even without sesamoiditis (e.g., significant hallux valgus or a severe cavus foot), then we must address this concurrently. Failure to do so can compromise the outcome of the sesamoidectomy.
• Concomitant Procedures: Consider augmenting the tibial sesamoidectomy with procedures like a lateral capsular release, medial capsular reefing, or a metatarsal or phalangeal osteotomy to prevent progressive deformity, particularly if significant hallux valgus is present. This integrated approach ensures long-term stability and function of the first ray.
• Fluoroscopy Setup: Plan for intraoperative fluoroscopy if there's any doubt about the exact location of the sesamoid or if fragmentation is extensive. This allows real-time confirmation of removal and assessment of surrounding structures.

Patient Positioning and Anesthesia

Let's get our patient ready.

• Anesthesia: An ankle block with mild sedation is typically well-tolerated and provides excellent intraoperative analgesia and postoperative pain control. General anesthesia is also an option, depending on patient preference and comorbidities.
• Positioning: Place the patient in a supine position on the operating table. Crucially, the lower extremity should be naturally externally rotated. This external rotation provides excellent exposure to the medial aspect of the forefoot, which is our surgical field. Ensure the foot is positioned comfortably on a padded pillow or bolster.
  

  
  
  

Figure 8: Intraoperative view showing the planned incision line and the natural external rotation of the foot, optimizing medial forefoot exposure.
* Tourniquet: We'll apply a well-padded supramalleolar Esmarch tourniquet. This provides a bloodless field, which is absolutely essential for the meticulous dissection required in this area. Ensure the tourniquet time is monitored closely.

Surgical Approach and Incision

The choice of incision is critical to minimize complications and optimize exposure.

• Preferred Incision: We will utilize a longitudinal medial skin incision. This incision is strategically placed slightly plantar to the standard incision used for a bunion excision.
• Why this approach?
  • Dorsomedial Incision: While sometimes described, a dorsomedial incision makes it exceedingly difficult to gain adequate exposure of the plantar aspect of the foot, where the sesamoid lies.
  • Plantar Medial Incision: A purely plantar medial incision is problematic because it often lies directly over the plantar medial cutaneous nerve and is located in a primary weight-bearing area, significantly increasing the risk of wound complications, painful scarring, and nerve injury.
• Incision Length: Typically, a 3-4 cm incision is sufficient, centered over the tibial sesamoid.

Intraoperative Masterclass: Tibial Sesamoidectomy

Alright, fellows, scalpel in hand. Let's begin.

1. Initial Dissection and Neurovascular Protection

Our first priority, always, is to protect the vital neurovascular structures.

• Skin Incision: Make your longitudinal medial skin incision with a #15 blade. Be precise, following the natural skin lines. Deepen the incision carefully through the subcutaneous tissue.

• Identifying the Plantar Medial Cutaneous Nerve: This is arguably the most critical step in the initial dissection. The plantar medial cutaneous nerve, a terminal branch of the medial plantar nerve, typically runs along the inferior border of the abductor hallucis muscle tendon, adjacent to the MTP joint capsule.

  • Use fine blunt dissection with Metzenbaum scissors or a small hemostat. Gently spread the tissues to visualize the nerve. It will appear as a yellowish, delicate structure.
  • Protection: Once identified, meticulously mobilize the nerve. We will retract it inferiorly, away from our surgical field. Some surgeons prefer dorsal retraction, but inferior retraction often provides a clearer path to the sesamoid.
  • Vessel Loop: For enhanced protection and clear visualization, carefully place a thin vessel loop around the nerve. This allows for controlled retraction and acts as a constant reminder of its location.
  • Surgical Warning:
    > Surgical Warning: The plantar medial cutaneous nerve is highly susceptible to injury during this approach. Direct trauma, excessive traction, or entrapment can lead to debilitating neuritic pain postoperatively. Always identify, mobilize, and protect this nerve meticulously.

• Exposing the Abductor Hallucis Tendon: Continue your dissection through the subcutaneous fat to expose the abductor hallucis tendon. The FHB lies deep to this.

2. Intra-articular Assessment and Decision Making

Now, we'll gain access to the MTP joint to assess the sesamoid's articular surface.

• Capsular Incision: Make a longitudinal incision in the medial MTP joint capsule, directly in line with your skin incision. This capsular incision should be dorsal to the fibers of the abductor hallucis tendon's insertion, which can be seen inserting onto the medial aspect of the proximal phalanx and medial sesamoid.
• Intra-articular Evaluation: With the capsule open, we can now directly visualize the articulation between the tibial sesamoid and the head of the first metatarsal.
  • Acute Fractures/Bipartite Sesamoids: Assess for significant displacement, step-off, or instability of the sesamoid fragments.
  • Chronic Cases: Look for articular cartilage injury on both the sesamoid and the metatarsal head facet, indicative of osteonecrosis, osteochondritis dissecans, or arthrosis. Note any chondromalacia or eburnation.
    

    
    
    

Figure 2: Intracapsular view showing the articulation between the tibial sesamoid and the metatarsal head. Note the smooth articular surfaces in a healthy joint.

3. Capsular Repair and Extra-articular Exposure

Before proceeding with the main excision, we'll close the joint capsule.

• Capsulotomy Repair: Carefully repair the longitudinal capsulotomy with a 2-0 nonabsorbable suture (e.g., Ethibond or Fiberwire). This is a crucial step to maintain MTP joint stability and prevent capsular scarring or adhesions that could lead to stiffness.
  

  
  
  

Figure 3: The tip of a Freer elevator positioned underneath the tibial sesamoid, prior to careful dissection of the flexor hallucis brevis complex. Note the longitudinal capsulotomy has already been repaired.

• Extra-articular Exposure: Now, we shift our focus to the plantar aspect. We need to expose the sesamoid through an extra-articular plantar medial incision, made directly in line with the fibers of the FHB tendon. This incision is deep to the capsular repair we just performed.
  • Use a #15 blade or a fine scalpel to carefully incise the plantar fascia and the fibers of the FHB tendon directly overlying the sesamoid.
    

    
    
    

Figure 4: Initial incision to separate the flexor hallucis brevis in line with its fibers, exposing the sesamoid.

4. Meticulous Sesamoid Excision

This is the heart of the procedure, demanding patience and precision.

• Grasping the Sesamoid: Use a small towel clamp or a Köcher clamp

Additional Intraoperative Imaging & Surgical Steps

REFERENCES

have not found any functional weakness of plantarflexion in any of their patients. Their patients were also able to return to their previous level of athletic participation with no functional deficit. Lee et al 10 also reported that 30% of their patients could not do a single-limb toe raise, indicating some plantarflexion weakness, but this did not affect any subsequent athletic activity.

1. Aper RL, Saltzman CL, Brown TD. The effect of hallux sesamoid resection on the effective moment of the flexor hallucis brevis. Foot Ankle Int 1994;15:462–470.

2. Aper RL, Saltzman CL, Brown TD. The effect of hallux sesamoid excision on the flexor hallucis longus moment arm. Clin Orthop Relat Res 1996;325:209–217.

3. Beaman DN, Nigo LJ. Hallucal sesamoid injury. Oper Tech Sports Med 1999;7:7–13.

4. Bizzaro AH. On the traumatology of the sesamoid structures. Ann Surg 1921;74:783.

5. Coughlin MJ. Sesamoid pain: causes and surgical treatment. AAOS Instructional Course Lectures 1990;39:23–35.

6. Dobas DC, Silvers MD. The frequency of partite sesamoids of the first metatarsal phalangeal joint. J Am Podiatry Assoc 1977;67: 880–882.

7. Helal B. The great toe sesamoid bones: the lus or lost souls of the Ushaia. Clin Orthop Relat Res 1981;157:82–87.

8. Inge GAL, Ferguson AB. Surgery of the sesamoid bones of the great toe: an anatomic and clinical study, with a report of forty-one cases. Arch Surg 1933;27:466–489.

9. Kaiman ME, Piccora R. Tibial sesamoidectomy: a review of the literature and retrospective study. J Foot Surg 1983;22:286–289.

10. Lee S, William JC, Cohen BE, et al. Evaluation of hallux alignment and functional outcome after isolated tibial sesamoidectomy. Foot Ankle Int 2005;26:803–809.

11. Mann RA, Coughlin MJ, Baxter D, et al. Sesamoidectomy of the great toe. Presented at the 15th Annual Meeting of the American Orthopaedic Foot and Ankle Society, Las Vegas, Jan. 24, 1985.

12. Nayfa TM, Sorto LA. The incidence of hallux abductus following tibial sesamoidectomy. J Am Podiatr Assoc 1982;72:617–620.

13. Richardson EG. Hallucal sesamoid pain: causes and surgical treatment. J Am Assoc Orthop Surg 1999;7:270–278.

14. Saxena A, Krisdakumtorn T. Return to activity after sesamoidectomy in athletically active individuals. Foot Ankle Int 2003;24:415–419.

15. Van Hal ME, Keene JS, Lange TA, et al. Stress fractures of the great toe sesamoid. Am J Sports Med 1982;10:122–128.

COMPLICATIONS
- Complications related to tibial sesamoid excisions can be separated into intraoperative complications, insufficient pain relief, functional weakness, and hallux malalignment.

• The most common intraoperative complication reported is injury to the plantar digital nerve.

• Patients typically complain of nerve irritation postoperatively. This generally responds well to observation or localized steroid injections. It occurs more commonly with fibular sesamoid excisions.

• Complete laceration of the nerve has never been reported, and this nerve irritation appears to be the result of aggressive retraction during surgery. This can be avoided by using meticulous technique with identification and protection of the plantar digital nerve during surgery.

• Isolated complete sesamoidectomies are thought to alter the mechanical balance of the hallux MTP joint. Clinical studies have described stiffness, functional loss, cock-up deformity, claw toe deformity, and the development of a hallux valgus deformity after isolated tibial sesamoidectomies. 8,9,11,12

• As noted earlier, identifying and addressing any significant malalignment of the hallux MTP can decrease the rate of future deformities.

FIG 10 • Preoperative ( A ) and postoperative ( B ) standing radiographs of the foot showing no change in the clinical alignment of the metatarsophalangeal joint after tibial sesamoidectomy. (From Lee S. Technique of isolated tibial sesamoidectomy. Techn Foot Ankle Surg 2004;3:85–90, with permission.)