Metatarsalgia

Metatarsalgia

CHAPTER 90 Metatarsalgia Prathap Jacob Joseph, MD Stuart Kigner, DPM Robert J. Scardina, DPM Synonyms Ball of foot pain Pain around the metatarsal h...

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CHAPTER 90

Metatarsalgia Prathap Jacob Joseph, MD Stuart Kigner, DPM Robert J. Scardina, DPM

Synonyms Ball of foot pain Pain around the metatarsal heads Plantar forefoot pain Anterior metatarsalgia Lesser metatarsalgia

ICD-10 Code M77.41 Metatarsalgia, right foot M77.42 Metatarsalgia, left foot M77.40 Metatarsalgia, unspecified foot

Definition Metatarsalgia refers to pain in the forefoot at the plantar surface in the region of the distal second and third metatarsals. This pain usually results from disruption of the normal transverse arch created at the region of the metatarsal heads with support from the transmetatarsal ligaments. The etiology is thought be related to one or a combination of three categories: primary, secondary, and iatrogenic. Primary metatarsalgia may result from anatomic abnormalities altering forces through the forefoot. Congenital and degenerative conditions affecting the great toe, including hallux valgus (bunion), hallux rigidus (degenerative arthritis), and sagittal plane first-ray hypermobility lead to a transfer of load to the lateral forefoot and lesser metatarsal heads (Fig. 90.1). A hammertoe with an associated dorsal contracture of a metatarsophalangeal (MTP) joint will cause a retrograde plantar flexion force on the metatarsal head (Fig. 90.2). Apart from the foot, conditions including ankle equinus, leg length discrepancy, scoliosis, and kyphosis may also result in increased forefoot pressures. Secondary metatarsalgia results from abnormal forces applied to the metatarsal region through indirect mechanisms. MTP joint synovitis occurs in conditions including rheumatoid arthritis, psoriatic arthritis, reactive arthritis, and systemic lupus erythematosus. The inflammation leads to weakening or rupture of the stabilizing structures around the joint, leading to dorsal subluxation of the toes on the lesser metatarsal heads.1 Degenerative arthritis of the lesser MTP joint may be caused by Freiberg infraction (metatarsal head avascular necrosis).

As the number of forefoot surgeries has increased, so too has the incidence of iatrogenic metatarsalgia.2 First metatarsal osteotomy, used in correction of hallux valgus, may result in excessive shortening or elevation of the first metatarsal, which then overloads the adjacent rays.3 

Symptoms Plantar forefoot pain is generally aggravated by weight bearing and is worse during the propulsive portion of the stance phase of gait (between heel lift and toe off). The sensation is often compared to stepping on a stone. There is usually insidious onset rather than a clearly identifiable inciting event. Lesser MTP joint morning stiffness may be present. Neuritic radiating pain may occur from irritation, inflammation, or tethering of neighboring plantar intermetatarsal nerves or may suggest another condition such as Morton neuroma. Poorly defined pain in the forefoot is a common early symptom in patients with rheumatoid arthritis. Other symptoms include MTP joint symmetric swelling and stiffness after rest. 

Physical Examination Examination identifies structural abnormalities that may predispose to metatarsalgia and provocative testing can either confirm or direct toward alternative diagnoses. On general inspection while weight bearing, note the presence of forefoot deformities including hallux valgus, hammertoes, medial or lateral subluxation of the toes, or MTP joint dorsal contractures. Pes planus alters the transmission of force through the foot and can predispose to metatarsalgia. Callus formation in the region of forefoot may indicate excessive loading in that region. The forefoot examination attempts to elicit pain on palpation directly beneath the metatarsal heads or MTP joints. Evaluate the excursion and pain of MTP joint passive range of motion and note the presence of swelling. Assess for first metatarsal hypermobility by applying a dorsiflexion force under the first metatarsal head. If hypermobility is present, the first metatarsal head will rise well above the second metatarsal head.4 Isolated gastrocnemius contracture, as confirmed by comparison of ankle dorsiflexion between the knee flexed and extended (Silfverskiӧld test), is associated with excessive pressure through the forefoot.5 Pain on palpation elicited with lateral compression of neighboring metatarsal heads that is accompanied by an audible click suggests a plantar intermetatarsal neuroma (Mulder sign). Stress fractures are commonly identified at the metatarsal neck, demonstrated by swelling, palpable 493

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Diagnostic Studies

FIG. 90.1 Cross-sectional view of metatarsal heads. Elevated first metatarsal head results in mechanical overload of lesser metatarsal heads. Hammer toe causing retrograde force on metatarsal head

Plantar plate tear FIG. 90.2  Hammertoe with associated plantar plate tear. The hammertoe causes a retrograde plantar flexion force on the metatarsal head.

pain, or bone fixation callus. Examine for dorsal translation of the proximal phalangeal base on the metatarsal head (drawer test) to identify plantar plate or capsule disruption. The “paper pull-out test” to evaluate toe purchase is performed by asking the patient to flex the toe against a piece of paper placed on the floor under the toe. The test result is positive if the paper cannot be pulled out from under the toe. If there is a V-shaped alignment of adjacent toes noted while the patient is standing, indicative of web space widening, early synovitis,6 plantar intermetatarsal neuroma, or other space-occupying mass may be present. Weight-bearing bilateral or unilateral heel raise while standing barefoot often aggravates metatarsalgia pain. During gait examination, observe for early heel-off, antalgic gait, excessive or insufficient subtalar joint pronation, asymmetry, and lack of toe purchase. Examine the shoe outsoles and insoles for signs of excessive or uneven wear indicative of areas of elevated pressure or abnormal foot mechanics. 

Functional Limitations Forefoot pain may limit standing, walking, and participation in high-impact activities, such as running or jumping. There will be a limitation to shoe style able to be worn comfortably. Metatarsalgia has its greatest impact on activities requiring prolonged standing or walking on hard floors (e.g., cashier, food preparation, or housekeeping jobs). Sales jobs requiring use of a dress shoe may be difficult. Walking speed may decrease while shopping or accessing public transportation. Recreational activities, such as walking, tennis, basketball, or running on a treadmill on an incline, may be particularly painful. 

Weight-bearing foot radiographs will demonstrate the relative lengths of the metatarsals and transverse plane splaying, if it is present. A forefoot axial view may reveal a structural abnormality of the metatarsal head condyles or relative prolapse of a metatarsal head due to plantar flexion. Metatarsal stress fractures may be identified, but less so on initial radiographs, which may appear unremarkable. Radiographs may also reveal a displaced fracture, foreign body, the stigmata of tumor, osteomyelitis, and noninflammatory or inflammatory arthritis. Ultrasonography and magnetic resonance imaging may be used to evaluate inflammatory arthritis, MTP joint plantar plate disruption, early stress fracture, ligament or tendon tear, abscess, and plantar intermetatarsal neuroma. Laboratory tests may be ordered if inflammatory arthritis or infection is suspected.  Differential Diagnosis Bursitis (intermetatarsal or plantar metatarsal head) Metatarsophalangeal (MTP) joint synovitis Flexor tendon sheath synovitis MTP joint capsulitis MTP joint plantar plate rupture Inflammatory and noninflammatory arthritis Freiberg infraction Intermetatarsal plantar neuroma Metatarsal stress fracture Infection (abscess or osteomyelitis) Plantar callus Intractable plantar keratoma Plantar wart (verruca plantaris) Foreign body Neoplasm (soft tissue or bone) Radiculopathy (lumbosacral) Tarsal tunnel syndrome Peripheral neuropathy or neuritis Vascular claudication Neurogenic claudication

Treatment Initial Focal plantar pressure can be reduced by applying a felt or foam rubber aperture pad to off-load a single metatarsal head, or a foam rubber or felt metatarsal pad or bar may be applied just proximal to a single metatarsal head or multiple neighboring metatarsal heads. Prefabricated pads are commercially available. The pads may be applied directly to the foot or to the shoe insole (Fig. 90.3). Cushioned shoe insoles composed of materials such as Plastazote, Poron, and Spenco may be used to replace the entire existing shoe insole. Prefabricated insoles with an incorporated metatarsal pad or bar are also available. Custom fabricated foot orthoses may be designed with a depression under the painful metatarsal head areas or with an incorporated metatarsal pad or bar. Although there is limited scientific evidence to support their use, foot orthoses and running shoes with antitorsional features may address abnormal biomechanical forces causing elevated pressure and shearing under the metatarsal heads. Wearing of a shoe with a full-length stiff outsole or “rocker” outsole under the forefoot is advisable.7

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avoid “transfer” metatarsalgia, may include strengthening of the peroneus longus muscle, manipulation to improve hallux plantar flexion, plantar and dorsal sliding of the hallux proximal phalanx, oscillating traction of the first MTP joint, and concentric strengthening of the hallux flexor and extensor muscles.13 

Procedures

Metatarsal pad

A diagnostic local anesthetic block of a plantar intermetatarsal nerve may be performed to differentiate between pain originating from an intermetatarsal neuroma and metatarsalgia pain originating from the metatarsal head or MTP joint. Relief of pain after injection of a local anesthetic such as lidocaine into the interspace (usually third) is diagnostic of neuroma. 

Surgery

Shoes should have a low heel height, soft insole, and extra depth to accommodate a custom or commercial cushion insole. For patients who stand most of the day because of their occupation, a cushion floor mat can be used. If a capsule or plantar plate tear is suspected (see Fig. 90.2), initial immobilization with a prefabricated walking boot may be indicated. Manually reducible dorsal MTP joint contractures may be addressed by applying tape around the base of the toe and securing it to the bottom of the foot.8 A prefabricated removable toe splint may also be effective for this condition. Oral nonsteroidal anti-inflammatory drugs may provide symptomatic relief. Topical preparations have not been found to be effective. Metatarsalgia secondary to rheumatoid or other inflammatory arthritis may be addressed by early use of oral disease-modifying antirheumatic drugs.9 

The Weil osteotomy, involving metatarsal head translation with or without elevation, has been used most commonly for years and is reported to achieve good to excellent results.14 Alternative percutaneous procedures, such as the distal metatarsal metaphyseal osteotomy (DMMO), are gaining popularity as they have reported greater postsurgical range of motion at the MTP joint.15,16 Metatarsalgia in patients with rheumatoid arthritis has traditionally been addressed by excision of the lesser metatarsal heads combined with fusion of the first MTP joint. Recently, with early institution of disease-modifying antirheumatic drugs resulting in sustained low disease activity and remission, MTP joint-sparing surgery has been recommended. However, at this time, there is limited evidence to support this approach.17 A rupture of the MTP joint plantar plate may be repaired primarily. Hammertoe surgery involving arthrodesis of the proximal interphalangeal joint combined with surgical capsular release and lengthening of the extensor tendons will decrease retrograde plantar pressure on the metatarsal head. In patients with isolated gastrocnemius shortening, proximal medial gastrocnemius release has been reported to reduce metatarsalgia symptoms.18 Bunionectomy with first metatarsal osteotomy, designed to decrease the angle between the first and second metatarsals, has been shown to decrease painful calluses under the second metatarsal head,19 and a lengthening osteotomy for an iatrogenic short first metatarsal has resulted in decreased metatarsalgia symptoms.20 

Rehabilitation

Technology

If there is posterior lower leg muscle tightness, gastrocnemius or soleus stretching exercises are recommended.10 Aquatic exercises and bicycle riding are preferable to exercises involving running and jumping. Decreasing stride length while running or fitness walking may also be helpful. Manipulation may be used to stretch out dorsal MTP joint contractures.8 After the Weil surgical procedure on a lesser metatarsal, vigorous physical therapy to strengthen the toe flexors and to maintain plantar flexion range of motion as soon as 1 week after surgery has been recommended.11,12 Rehabilitation after hallux valgus surgery, in an effort to

There is no specific technology for the treatment or rehabilitation of this condition. 

Metatarsal bar

FIG. 90.3 Metatarsal pad attached to shoe insole. The metatarsal pad and bar are designed to redistribute pressure away from metatarsal heads.

Potential Disease Complications Metatarsalgia pain may result in functional limitation, including antalgic gait, and may lead to falls in the elderly patient population. Rupture of the plantar plate and collateral ligaments may result in MTP joint instability, dorsal toe subluxation, and transverse plane positional toe deformity, including overlapping toes. 

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Potential Treatment Complications Intra-articular corticosteroid injections, especially acetate steroids, are generally not recommended in the presence of lesser MTP joint predislocation syndrome.8 After corticosteroid injection, MTP joint dislocation21 and plantar fat pad atrophy have been reported.22 Other adverse reactions after injection of corticosteroids include skin hypopigmentation at injection site, infection, transient elevated blood glucose concentration, and postinjection flare (pain). Neuroma excision surgery was found to be more technically demanding because of the degree of fibrosis after a series of 20% ethyl alcohol (sclerosing) injections,23 which may also result in adhesive neuritis or “stump” neuroma formation. Topical salicylic acid used to treat painful plantar calluses may injure the skin and lead to open wounds and infection, especially in patients with diabetes. Adverse reactions associated with oral nonsteroidal anti-inflammatory drugs and disease-modifying antirheumatic drugs are listed elsewhere in the text. Shoes with stiff rocker outsoles may cause gait instability and possibly lead to falls, especially in the elderly patient population. Because of the difficulty in precisely determining the optimal length of a metatarsal when a shortening osteotomy is performed to address metatarsalgia, excessive shortening may result in metatarsalgia of an adjacent metatarsal head and insufficient shortening may lead to some degree of persistent pain.10 A not uncommon complication of the Weil lesser metatarsal osteotomy is a “floating toe” that does not purchase the floor while standing and walking.10 Complications of foot orthotic therapy may include mild strain of ligaments, tendons, or muscles; orthotic edge irritation of the skin; and shoe fit difficulty. Improper positioning of a metatarsal pad may result in elevated pressure under the metatarsal head.

References 1. Loveday DT, Jackson GE, Geary NP. The rheumatoid foot and ankle: current evidence. Foot Ankle Surg. 2012;18:94–102. 2. Besse JL. Metatarsalgia. Orthop Traumatol Surg Res. 2017. pii: S1877-0568(16)30189-X. 3. Zembsch A, Trnka H, Ritschl P. Correction of hallux valgus metatarsal osteotomy versus excision arthroplasty. Clin Orthop Relat Res. 2000;376:183–194.

4. Roberts MM, Greisberg J. Examination of the foot and ankle. In: DiGiovanni CW, Greisberg J, eds. Foot and Ankle: Core Knowledge in Orthopaedics. Philadelphia: Elsevier Mosby; 2007:10–15. 5. Jastifer JR, Martson J. Gastrocnemius contracture in patient with and without foot pathology. Foot Ank Int. 2016;37(11):1165–1170. 6. Panchbhavi VK, Trevino S. Clinical tip: a new clinical sign associated with metatarsophalangeal joint synovitis of the lesser toes. Foot Ankle Int. 2007;28:640–641. 7. Jeng CL, Logue J. Shoes and orthotics. In: Pinzur MS, ed. Orthopaedic Knowledge Update: Foot and Ankle, 4th ed. Rosemont, IL: American Academy of Orthopaedic Surgeons; 2008:15–24. 8. Yu GV, Judge MS, Hudson JR, et al. Predislocation syndrome. Progressive subluxation/dislocation of the lesser metatarsophalangeal joint. J Am Podiatr Med Assoc. 2002;92:182–199. 9. Saag KG, Teng GG, Patkar NM, et al. American College of Rheumatology 2008 recommendations for the use of nonbiologic and biologic disease-modifying antirheumatic drugs in rheumatoid arthritis. Arthritis Rheum. 2008;59:762–784. 10. Espinosa N, Maceira E, Myerson MS. Current concept review: metatarsalgia. Foot Ankle Int. 2008;29:871–879. 11. Barouk P, Bohay DR, Trnka HJ, et al. Lesser metatarsal surgery. Foot Ankle Spec. 2010;3:356–360. 12. Myerson MS. Reconstructive Foot and Ankle Surgery, 2nd ed. Philadelphia: WB Saunders; 2010. 13. Schuh R, Hofstaetter SG, Adams SB, et al. Rehabilitation after hallux valgus surgery: importance of physical therapy to restore weight bearing of the first ray during the stance phase. Phys Ther. 2009;89:934–945. 14. Hofstaetter SG, Hofstaetter JG, Petroutsas JA, et al. The Weil osteotomy: a seven year follow-up. J Bone Joint Surg Br. 2005;87:1507–1511. 15. Redfern D, Vernios J. Percutaneous surgery for metatarsalgia and the lesser toes. Foot Ankle Clin N Am. 2016;21:528–550. 16. Yeo N, Loh B, Chen J, et al. Comparison of early outcome of Weil osteostomy and distal metatarsal mini-invasive osteostomy for lesser toe metatarsalgia. J Orthop Surg. 2016;24(3):350–353. 17. Jeng C, Campbell J. Current concept review: the rheumatoid forefoot. Foot Ankle Int. 2008;29:959–968. 18. Morales-Muñoz P, Sanz P, Pérez J, et al. Proximal gastrocnemius release in the treatment of mechanical metatarsalgia. Foot Ankle Int. 2016;37(7):782–789. 19. Mann RA, Rudicel S, Graves S. Repair of hallux valgus with a distal soft-tissue procedure and proximal metatarsal osteotomy. J Bone Joint Surg Am. 1992;74:124–129. 20. Singh D, Dudkiewicz I. Lengthening of the shortened first metatarsal after Wilson’s osteotomy for hallux valgus. J Bone Joint Surg Br. 2009;91:1583–1586. 21. Reis ND, Karkabi S, Zinman C. Metatarsophalangeal joint dislocation after steroid injection. J Bone Joint Surg Br. 1989;71:864. 22. Basadonna P, Rucco V, Gasparini D, et al. Plantar fat pad atrophy after corticosteroid injection for an interdigital neuroma: a case report. Am J Phys Med Rehabil. 1999;78:283–285. 23. Hughes RJ, Ali K, Jones H, et al. Treatment of Morton’s neuroma with alcohol injection under sonographic guidance: follow-up of 101 cases. AJR Am J Roentgenol. 2007;188:1535–1539.