I. Introduction
A. Epidemiology
1. Deformities of the lesser (second through fifth) toes can present in isolation or in association with hallux deformities.
2. The metatarsophalangeal (MTP) joint region is the most frequently affected, followed by the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints.
B. Contributing factors
1. Fashion in womens' footwear
a. High heels and narrow, pointed toe boxes
b. Inappropriately small shoe size
2. Advancing age
3. Neuromuscular disorders
4. Congenital deformities
5. Inflammatory arthropathies
6. Repetitive trauma to the forefoot region
7. Variations in bony anatomy of the forefoot
a. Associated valgus alignment of the hallux
b. Relatively long lesser metatarsal
c. Irregularly shaped bony phalanx
II. Second Metatarsophalangeal Joint Synovitis
A. Overview/epidemiology
1. Second MTP joint synovitis is a monoarticular synovitis.
2. The second MTP joint is the joint most frequently affected in MTP synovitis.
*Steven M. Raikin, MD, or the department with which he is affiliated has received research or institutional support from Synthes.
3. Predisposing factors are an elongated second metatarsal relative to the first metatarsal (Morton foot), or an associated hallux valgus deformity.
B. Pathoanatomy
1. The synovitis stretches the capsuloligamentous apparatus of the MTP joint, resulting in frontal and axial plane instability and deformity.
2. Subsequent attenuation of the plantar plate results in extension at the MTP joint and sagittal plane deformity.
3. The resulting conditions include MTP instability and potential subsequent dorsal dislocation, and a predisposition to developing hammer toe deformities.
C. Evaluation
1. History and physical examination
a. Patients present with pain, warmth, palpable fullness, and tenderness to palpation in the second MTP joint region in the absence of trauma or systemic inflammatory conditions.
b. Clinical examination reveals a swollen, warm, and tender second toe at the level of the MTP joint.
c. Tenderness may be greater plantarly (over the plantar plate), dorsally (over the dorsal capsule), or globally around the MTP joint.
d. In the predislocation stages, the deformity is frequently passively correctable, but range of motion, particularly plantar flexion, is usually reduced.
e. Instability of the second MTP joint may be present.
i. The instability is clinically reproducible via the dorsal drawer test, where the metatarsal head and phalanx are individually stabilized and a dorsal translation stress is applied.
ii. Attenuation of the plantar plate results in abnormal dorsal subluxation of the joint.
f. Progressive deformity may result in the toe crossing over one of the adjacent toes in either varus or valgus if one of the collateral ligaments is disrupted in addition to the plantar plate. This condition is known as crossover toe deformity.
g. Many patients have tenderness within the second web space that is secondary to inflammation or extrinsic pressure on the interdigital nerve from the MTP synovitis. This can result in neuritic symptoms that mimic a Morton neuroma. Care must be taken to differentiate second MTP joint synovitis from an interdigital neuroma because corticosteroid injections to treat an interdigital neuroma may further weaken the capsuloligamentous structures at the MTP joint, resulting in progressive deformities.
2. Imaging
a. Radiographs
i. Weight-bearing AP radiographs should be obtained and assessed for widening or medial-lateral joint-space imbalance of the MTP joint, which is consistent with synovitis, and dorsal subluxation of the MTP joint, which may result in the joint space appearing narrowed or the base of the proximal phalanx overlapping the metatarsal head. The toe may been seen deviating into varus or valgus if a crossover toe has developed.
ii. Lateral radiographs may demonstrate hyperextension of the MTP joint or dorsal subluxation of the proximal phalanx.
b. MRI or ultrasound may be performed when the diagnosis is unclear or to quantify the extent of the ligamentous or plantar plate disruption.
D. Treatment
1. Nonsurgical
a. Initial treatment includes activity and shoe-wear modifications, nonsteroidal anti-inflammatory medications, and external support of the MTP joint.
b. External support is achieved with a crossover taping of the MTP joint or with the application of a commercially available Budin-type toe splint.
c. Nonsurgical treatment should be continued for 10 to 12 weeks and be followed by avoidance of shoe wear that can predispose to the condition.
2. Surgical
a. Indications—If nonsurgical treatment is unsuccessful or a fixed deformity cannot be accommodated with modifications in shoe wear, surgery may be indicated.
b. Surgical procedures
i. If no deformity is present, a synovectomy of the joint is indicated.
ii. In the presence of a long second metatarsal, a joint-preserving shortening osteotomy should be performed. This is a short oblique osteotomy at the junction of the metatarsal head and neck that allows the metatarsal head to be slid proximally, rebalancing the metatarsal cascade. This also allows the capsuloligamentous structures and plantar plate to be relaxed and rebalanced in appropriate alignment.
iii. In the absence of a long second metatarsal, sagittal plane deformities are corrected with a soft-tissue reconstruction such as a flexor digitorum longus (FDL)-to-extensor digitorum longus (EDL) tendon transfer (Girdlestone-Taylor procedure) or an MTP capsular release and extensor tendon lengthening. Crossover toe deformities are corrected with an extensor digitorum brevis transfer.
c. Complications—During surgical correction of a chronically dislocated MTP joint, vascular compromise of the toe may occur as a result of vascular stretching while reducing the joint. In this situation, the procedure may need to be reversed to save the digit.
III. Freiberg Infraction
A. Overview
1. Infraction of the metatarsal head was first described by Freiberg in 1914.
2. The term infraction is a combination of infarction and fracture.
3. The second metatarsal head is the most commonly involved, predominantly in the dorsal aspect. As the condition progresses, the metatarsal head undergoes collapse.
4. The condition may result from recurrent microtrauma or osteonecrosis of the metatarsal head, leading to subchondral collapse.
B. Evaluation
1. History and physical examination—Patients present with localized pain and swelling and stiffness of the MTP joint that is exacerbated by weight-bearing activities.
2. Imaging
|
a. |
Radiographs |
|
|
i. |
In the precollapse stage, initial radiographs may be normal. |
|
[
Table 1. Smillie Classification of Freiberg Infraction]
|
ii |
Collapse is initially seen radiographically as flattening of the metatarsal head and subchondral sclerosis. Progression of the condition results in development of arthritic changes on both sides of the MTP joint. |
|
|
b. |
MRI—Before radiographic changes are noted, the diagnosis can be made by MRI, which will reveal patchy edema in the metatarsal head and precollapse changes that are consistent with osteonecrosis. |
|
3. Classification—The Smillie classification of Freiberg infraction is shown in Table 1.
C. Treatment
1. Nonsurgical
a. Initial treatment includes unloading and protecting the second metatarsal head.
b. A short leg cast extended to the toes or a fracture boot, worn for a 4- to 6-week period and followed by several months in a stiff-soled shoe with a metatarsal bar, may reverse early stage 1 involvement or quell the inflammatory process that causes early-phase symptoms.
2. Surgical
|
a. |
Surgery is indicated for recalcitrant cases. |
|
b. |
A dorsal closing-wedge osteotomy of the metatarsal head is commonly used. The procedure resects the collapsed dorsal diseased bone and cartilage and brings the less affected plantar cartilage into contact with the articular cartilage of the proximal phalanx. At the same time, the metatarsal is shortened (via the closing wedge), unloading the predisposing stress on the metatarsal head. |
[
Table 2. Deformities of the Lesser Toes]
|
c. |
An isolated debridement of the joint may be performed in mild and moderate symptomatic cases. |
|
d. |
A partial head resection (DuVries arthroplasty) may be required when there is stage 4 and 5 involvement or when the plantar cartilage is not adequate to reconstruct the metatarsal head. |
IV. Deformities of the Lesser Toes
A. Overview
1. Deformities of the lesser toes result from an imbalance between the intrinsic and extrinsic musculotendinous units of the toes.
2. With hyperextension at the MTP joint, the strong flexors overpower the intrinsic extensors of the interphalangeal (IP) joints. This leads to flexion deformities at the IP joints and extension deformities at the MTP joints.
3. Lesser MTP deformity starts with dysfunction of the plantar plate.
4. Table 2 summarizes the deformities of the lesser toes and the involvement of the MTP, PIP, and DIP joints.
B. Mallet toe deformity
1. Definition—Mallet toe is a hyperflexion deformity at the DIP joint (
Figure 1). The deformity may be flexible or fixed.
2. Evaluation/clinical presentation
a. Pain and callosities at the dorsum of the DIP joint will be present.
b. Frequently, "tip calluses" (painful calluses that form at the distal tip of the toe as it impacts the ground) will also be present.
3. Treatment
a. Nonsurgical—Treatment includes wearing shoes with high toe boxes and the use of foam (or silicone gel) toe sleeves or crest pads.
[Figure 1. Illustration of mallet toe deformity.]
[
Figure 2. Illustration of hammer toe deformity.]
[
Figure 3. Illustration of claw toe deformity.]
b. Surgical
i. Surgical correction is dependent on the flexibility of the deformity.
ii. A flexible deformity can be corrected with a percutaneous release of the FDL tendon at its insertion into the base of the proximal phalanx.
iii. In the more commonly seen fixed deformity, a resection of the distal condyles of the middle phalanx and repair of the extensor tendon combined with temporary wire fixation should be added to the correction.
iv. Recurrent MTP joint instability after surgical correction is usually due to persistent plantar plate dysfunction.
C. Hammer toe deformity
1. Overview
a. Hammer toe is a flexion deformity at the PIP joint and an extension deformity at the MTP and DIP joints (Figure 2).
b. It is the most common deformity seen in the lesser toes.
2. Evaluation—Clinical presentation includes pain and callus formation over the dorsum of the PIP joint, and difficulty with shoe wear.
3. Treatment
a. Nonsurgical—Treatment includes wearing shoes with high toe boxes and the use of foam (or silicone gel) toe sleeves.
b. Surgical
i. Indications—Surgery is indicated when non-surgical treatment fails to provide adequate relief of symptoms.
ii. In the absence of MTP pathology, surgical correction of hammer toes involves resection of the distal condyles of the proximal phalanx of the toe. Resection may be combined with an FDL tenotomy (performed either via the dorsal incision used for the condylar resection or through a plantar percutaneous release). The toe should be pinned with temporary wire fixation.
iii. If the MTP joint is involved, correction is the same as for claw toe deformity (see Claw Toe Deformity).
D. Claw toe deformity
1. Definition—Claw toe is an extension deformity at the MTP joint combined with hyperflexion at the PIP joint and DIP joints (Figure 3). The deformity may be flexible or fixed.
2. The difference between a hammer toe and a claw toe is the positioning of the DIP joint.
3. Pathoanatomy
[
Table 3. Radiographic Classification of Bunionette Deformity]
a. As the claw toe develops, the flexor tendons pull the IP joints into flexion and the MTP joint into extension. This acts to depress the metatarsal head and pull the plantar fat pad distally, resulting in metatarsalgia, callus, or ulcer formation.
b. The primary deficiency at the MTP joint level is dysfunction or tearing of the plantar plate, which usually holds the base of the phalanx aligned with the metatarsal head.
4. Clinical presentation
a. The patient may report pain at the level of the unstable MTP joint (this may dislocate dorsally).
b. A claw-type deformity of the toe is seen.
c. Metatarsalgia and callus formation under the depressed metatarsal head are common.
d. The flexed IP joints tend to rub against the toe box of the shoe, resulting in callus formation and pain.
5. Treatment
a. Nonsurgical—Initial treatment is aimed at shoe-wear modification, with adequate plantar padding (including metatarsal pad inserts) and a shoe with a high toe box. Crest pads may also be used.
b. Surgical
i. The MTP imbalance is addressed with an extensor tendon Z-plasty lengthening and MTP capsular release. This may be combined with an oblique metatarsal shortening osteotomy and/or an FDL-to-EDL (Girdlestone-Taylor) tendon transfer, depending on the length of the affected metatarsal and the achieved balance of the MTP joint.
[
Figure 4. Types of bunionette deformities. A, Type 1 is associated with an enlarged fifth metatarsal head with a normal metatarsal shaft and alignment. B, Type 2 is associated with lateral bowing (outward curvature) of the fifth metatarsal. C, Type 3 is associated with increased lateral bowing of the fifth metatarsal (IMA >8° between the fourth and fifth metatarsal shafts).]
ii. The hammer toe and mallet toe are corrected via a proximal phalangeal distal condylar resection and FDL tenotomy. A wire is then placed across the DIP, PIP, and MTP joints for temporary stabilization.
c. Complications—Persistent plantar plate dysfunction may result in recurrence of the deformity.
E. Bunionette deformity
1. Definition—A bunionette deformity, or tailor's bunion, is a prominence of the lateral aspect of the fifth metatarsal head.
2. Clinical presentation—The patient presents with pain and bursa formation resulting from painful rubbing of the prominence against the lateral counter of a shoe.
3. Imaging—Weight-bearing AP radiographs should be obtained.
4. Classification—Types of bunionette deformities, based on weight-bearing AP radiographs, are shown in Table 3 and Figure 4.
5. Treatment
a. Nonsurgical—Initial treatment involves wearing properly fitting shoes with a wider toe box and padding of the lateral prominence.
b. Surgical—Surgical treatment is dependent on the type of bunionette deformity that is present, and it is rarely necessary.
i. Type 1—Lateral condylectomy with reefing of the lateral MTP joint capsule. In cases where the deformity is large and longstanding, combining the lateral condylectomy with a distal metatarsal chevronmedializing osteotomy is indicated.
ii. Types 2 and 3
(a) If the intermetatarsal angle (IMA) is <12° or a small bow is present, a distal chevron osteotomy can be performed. A maximum medializing slide of 2 to 3 mm is recommended; a larger slide interval will result in an unstable osteotomy.
(b) Only a larger bunionette deformity with an IMA >12° or a large bow is treated with oblique diaphyseal rotational osteotomy and screw fixation.
iii. Metatarsal head resection results in unacceptable instability of the MTP joint and should be reserved for salvage procedures.
Top Testing Facts
1. Second MTP joint synovitis in the presence of a long second metatarsal is surgically treated with a short oblique osteotomy at the junction of the metatarsal head and neck that allows the metatarsal head to be slid proximally.
2. In the absence of a long second metatarsal, sagittal plane deformities are corrected with a soft-tissue reconstruction such as an FDL-to-EDL tendon transfer (Girdlestone-Taylor procedure) or an MTP capsular release and extensor tendon lengthening.
3. Surgical treatment of a Freiberg infraction commonly involves a dorsal closing-wedge osteotomy of the metatarsal head.
4. Lesser MTP deformity starts with dysfunction of the plantar plate.
5. Recurrent MTP joint instability after surgical correction is usually due to persistent plantar plate dysfunction.
6. Mallet toe is a hyperflexion deformity at the DIP joint. The deformity may be flexible or fixed.
7. Hammer toe is a flexion deformity at the PIP joint and an extension deformity at the MTP and DIP joints. It is the most common deformity seen in the lesser toes.
8. Claw toe is an extension deformity at the MTP joint combined with hyperflexion at the PIP joint and DIP joints. The deformity may be flexible or fixed.
9. The difference between a hammer toe and claw toe is the positioning of the DIP joint.
10. Only a larger bunionette deformity with an IMA >12° or a large bow is treated with an oblique diaphyseal rotational osteotomy and screw fixation.
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