Lesser metatarsophalangeal instability

Pain in the second MTP with synovitis and instability was first described in 1985 by Mann et al, who considered that the instability was due to synovitis of uncertain origin, perhaps associated with impingement from hallux valgus. Several relatively small studies have elucidated this problem further.

Yao demonstrated the association with plantar plate tears. Deland (2000) and Powless and Elze (2001) extended the understanding of capsular pathology.

Clinical assessment

The typical patient is a middle-aged woman. Most patients have no history of trauma or inflammatory arthritis. There is a strong association with hallux valgus.

Symptom patterns:

• MTPJ pain, often under the joint
• Progressive hammertoe or over-riding toe deformity – sometimes the only complaint is of the PIPJ rubbing on the shoe
• Pain and/or under the joint followed by progressive deformity when the pain may become milder
• Sometimes difficult to differentiate from interdigital neuroma or bursitis – test injections are useful

Examination may show:

• Puffiness around one or more MTP joints (usually the second)
• Tenderness around the joint, especially under the plantar plate
• Hammertoe and/or crossover toe deformity
• Instability, subluxation or dislocation of the MTP joint – probably about 10-20% present with fixed dislocation
• Hallux valgus

The Thompson draw test demonstrates instability with the MTP joint flexed 20deg and the proximal phalanx drawn up and down.

• Grade 1 - <50% vertical translocation
• Grade 2 – 50-100% translocation
• Grade 3 – dislocatable

The toe deformity may also be classified according to the Blackburn classification

Management

Flexible, non-dislocated toe

• Advice on shoe wear
• Toe taping
• Steroid injection (if first line treatment fails)
• Metatarsal dome insoles or shoe stiffening may be helpful for some patients

Stiff PIPJ deformities with rubbing will usually not tolerate conservative treatment and require surgery with a staged procedure

• PIPJ arthroplasty
• MTPJ soft tissue release almost always
• Flexor-extensor transfer often (medial crossover toes may be better with a EDB tenodesis)
• Weil osteotomy to accommodate reduction occasionally

Severely subluxated or dislocated toes, often with severe metatarsalgia due to the Stainsby plunger phenomenon, almost always require surgery.

• Most joints can be reduced by soft tissue release and often a Weil osteotomy; a flexor-extensor transfer is then usually required for stability
• Some joints are so degenerate or incongruent that it is best to do a soft tissue release and a Stainsby procedure, warning the patient that this will relieve the metatarsalgia at the cost of a short floppy toe
• Some elderly patients prefer amputation of the toe in which case a spacer is sdvisable to prevent collapse of the hallux into the space

Most patients are significantly improved by surgical reconstruction, but it is important to warn of:

• Most toes are stiff
• Some residual discomfort in 30%
• Recurrent dislocation in 15%
• Failure in about 10%
• Some toes feel “odd”
• Infection
• Occasional neurovascular injuries

References

• Cohen I, et al. Flexor to extensor tendon transfer: a new method of tensioning and securing the tendon. Foot Ankle Int (2001); 22(1): 62-3.
• Coughlin MJ. Second metatarsophalangeal joint instability in the athlete. Foot Ankle (1993); 14(6): 309-19.
• Deland JT, et al. Collateral ligament reconstruction of the unstable metatarsophalangeal joint: an in vitro study. Foot Ankle (1992); 13(7): 391-5.
• Deland JT, et al. The medial crosssover toe: a cadaveric dissection. Foot Ankle Int (2000); 21(5): 375-8.
• Ford LA, et al. Stabilization of the subluxed second metatarsophalangeal joint: flexor tendon transfer versus primary repair of the plantar plate. J Foot Ankle Surg (1998); 37(3): 217-22.
• Fortin PT, et al. Second metatarsophalangeal joint instability. Foot Ankle Int (1995); 16(5): 306-13.
• Gazdag A, et al. Surgical treatment of patients with painful instability of the second metatarsophalangeal joint. Foot Ankle Int (1998); 19(3): 137-43.
• Johnston RB, 3rd, et al. The plantar plate of the lesser toes: an anatomical study in human cadavers. Foot Ankle Int (1994); 15(5): 276-82.
• Loretz L, et al. Significance of the suspensory and collateral ligaments in lesser metatarsal neck surgery. J Foot Surg (1984); 23(2): 123-8.
• Mann RA, et al. Monarticular nontraumatic synovitis of the metatarsophalangeal joint: a new diagnosis? Foot Ankle (1985); 6(1): 18-21.
• Miller SD. Technique tip: forefoot pain: diagnosing metatarsophalangeal joint synovitis from interdigital neuroma. Foot Ankle Int (2001); 22(11): 914-5.
• Mizel MS, et al. Nonsurgical treatment of monarticular nontraumatic synovitis of the second metatarsophalangeal joint. Foot Ankle Int (1997); 18(7): 424-6.
• Myerson MS. Arthroplasty of the second toe. Semin Arthroplasty (1992); 3(1): 31-8.
• Powless SH, Elze ME. Metatarsophalangeal joint capsule tears: an analysis by arthrography, a new classification system and surgical management. J Foot Ankle Surg 2001; 40:374-89
• Thompson FM, Hamilton WG. Problems of the second metatarsophalangeal joint. Orthopedics 1987; 10:83-9
• Thompson FM, et al. Flexor tendon transfer for metatarsophalangeal instability of the second toe. Foot Ankle (1993); 14(7): 385-8.
• Trepman E, et al. Nonoperative treatment of metatarsophalangeal joint synovitis. Foot Ankle Int (1995); 16(12): 771-7.
• Umans HR, et al. The plantar plate of the lesser metatarsophalangeal joints: potential for injury and role of MR imaging. Magn Reson Imaging Clin N Am (2001); 9(3): 659-69, xii.
• Yao L, et al. Magnetic resonance imaging of plantar plate rupture. Foot Ankle Int (1996); 17(1): 33-6.
• Yao L, et al. Plantar plate of the foot: findings on conventional arthrography and MR imaging. AJR Am J Roentgenol (1994); 163(3): 641-4.