Lesser Toe Deformities
Deformities of the lesser toes most commonly occur gradually, however, occasionally be brought on by trauma.
Hallux valgus can contribute to the formation and propagation of lesser toe deformities as the resultant shortening of the first ray may slacken the plantar fascia and weaken the windlass effect leading to greater strain on the lesser toes.
Gradually, the supporting structures of the lesser toes fail. Lesser toe deformities can also be associated with inflammatory arthropathies, synovitis, diabetes, neuromuscular disorders and ill-fitting or high-heeled footwear.
The relative length of the metatarsals is important in symptomatology of lesser toe disorders. In the normal foot morphotype, the second metatarsal is the longest lesser metatarsal and the fifth is the shortest.
The first metatarsal is often similar in length to the second (square foot morphology), or shorter (Greek type foot), or longer (Egyptian foot type). If one or more metatarsals are relatively longer or plantar-flexed, this can result in abnormal pressure and metatarsalgia.
Patients may present with pain, swelling, deformity, difficulty in shoewear or cosmetic appearance. It is important to assess their main concern and expectations.
Weightbearing plain x-rays are important initial imaging and often may require an MRI scan to delineate the accurate pathology.
Hammer toe is defined as a primary flexion deformity of the PIPJ, with or without hyperextension at the MTPJ, but with a neutral or hyperextended DIPJ.
The pull of the extensor tendons is mainly transmitted to the MTPJ via the extensor sling. The extensors are therefore unable to correct the PIPJ deformity, but hyperextension may occur at the MTPJ instead.
This may progress to MTPJ instability as the plantar plate becomes attenuated. The DIPJ remains largely unaffected, or may become hyperextended by the pull of the extensors via the lateral slips. Initially the deformity is flexible, but gradually may become rigid.
Dhukaram et al. described 3 types of hammer toes:
Type 1 – reducible MTPJ and PIPJ
Type 2 – reducible MTPJ but a fixed PIPJ
Type 3 – fixed or subluxed MTPJ and a fixed PIPJ
This should always be tried as the first line of treatment as the majority of patients respond to these measures. These include footwear modifications (wider shoes with a larger toe box and off-loading shoes) which may help alleviate symptoms and prevent progression. Pressure areas may be helped by toe sleeves and padding over the dorsum of the PIPJ and under the MT heads.
Where non-operative measures have failed, surgery may be considered depending on patient’s symptoms and functional difficulties. Treatment aims to restore normal alignment of the joints and to restore the balance between the flexors, extensors and intrinsic.
FDL and FDB tenotomise and tenodesis to the extensor hood was first described by Taylor in 1951. Variations of this procedure are now widely used in the treatment of hammer toes. Barbari and Brevig performed this procedure on 39 flexible claw toes and obtained an 84% satisfaction rate.
Boyer and DeOrio performed the procedure on 79 hammer toes with an 89% satisfaction rate and no floating toe problems. Losa et al performed a meta-analysis of 515 flexorto-extensor transfers for lesser toe deformities and found patient satisfaction to be 87%.
For fixed PIPJ deformities the PIPJ is excised or fused. In cases where the MTPJ is stable, this procedure is often sufficient. Coughlin et al reported on 118 toes treated with PIPJ resection and stabilised with a percutaneous wire and reported 81% fusion rates, while the rest developed a fibrous union. Pain was improved in 92% of cases, and 84% of patients were satisfied. PIPJ excision without fusion may result in malalignment and instability.
The DIPJ flexion deformity may occur due to direct pressure from the shoe and eventually the FDL tightens resulting in a fixed deformity. This may gradually cause callosities at the tip of the toe and pressure on the nail.
After conservative treatment fails, surgery is usually considered due to persistent symptoms and functional difficulties. Evidence on the best treatment of an isolated adult mallet toe is sparse. Flexible mallet toes are usually treated by percutaneous flexor tenotomy.
A fixed deformity is treated by excision of the DIPJ and fusion. Coughlin reported 72 mallet toes treated with fusion and reported bony fusion in 72% cases and fibrous union in the remainder, 86% satisfaction rate and 97% symptomatic improvement. For patients with significant ulceration, terminalisation is an alternative to fusion.
The exact mechanism behind the development of claw to is unclear however the first causative deformity is thought to be hyperextension at the MTPJ. It is commonly seen in neuromuscular disorders. When the MTPJ becomes chronically hyperextended, the intrinsics shorten, the flexors are pulled taut and flex the IPJs. Initially this clawing may be flexible and dynamic but gradually as the plantar plate ruptures, MTPJ subluxes and the deformity becomes rigid.
Once the conservative treatment fails with persistent symptoms, surgical treatment is considered. Treatment must address the deformities at the PIPJ, DIPJ and MTPJs. If MTPJ instability exists, this should be addressed first. Myerson and Shereff suggested that for mild, flexible claw toe, the PIPJ deformity may be corrected by an FDB tenotomy. However, the unopposed pull of the intrinsics and extensors may then cause hyperextension of the toe at the MTPJ and so a flexor-to-extensor transfer is recommended.
Crossover toes are often one of the most challenging lesser toe deformities to correct. Crossover toe occurs if there is a unilateral or partial rupture of the plantar plate and a deficiency in one of the collaterals. Medial deviation is more common and the second toe is most commonly affected.
Haddad et al. defined the stages of subluxation for crossover toe as follows:
Stage 1 – mild deviation
Stage 2 – moderate deviation
Stage 3 – overlap of hallux
Stage 4 – total dislocation
Initially the deformity may remain flexible, however with time the capsule, extensors and other soft tissue shorten and the deformity becomes rigid. Deland and Sung performed cadaveric dissections and found that in the medial crossover toe there was lateral attenuation of the plantar plate with significant soft-tissue changes.
For mild crossover toe, soft-tissue release and capsular reefing may be sufficient. For more severe deformities, flexor-to-extensor transfer has traditionally been used. Myerson and Jung reported good results from correction of 64 feet but only a 68% satisfaction rate. For slightly less severe deformities an extensor transfer has also been used.
Barca and Acciaro reported on 30 toes treated in this fashion, with 83% good to excellent results and a 3% recurrence rate. Fuhrmann reported on 23 patients, with improvement in alignment in all cases. However, four patients with concomitant hallux valgus all had recurrence. Haddad et al. found that an extensor transfer worked well for mild to moderate crossover deformity, but flexor-to-extensor transfer was superior in more advanced deformity.
Devos Bevernage et al. reported on 25 feet with medial translation Weil’s osteotomy and described 68% of toes as stable and 30% as floating. Basal proximal phalangeal osteotomy has also been described to realign the toe.
Kilmartin and O’Kane performed the procedure in 26 valgus second toes without additional soft-tissue procedures. Although they did not achieve full correction, 73% patients were satisfied, 19% had floating toes 15% had recurrence.
In cases of a crossover toe with a unilateral plantar plate tear, repair of the plantar plate is increasingly popular, although there is little literature to support the results of this technique.
In elderly patients with severe deformity, amputation may on occasion be preferable to significant bony and soft-tissue correction. In these cases the accompanying hallux deformity need not be corrected. Gallentine and DeOrio report on 17 toes amputated through the MTPJ with an 82% satisfaction rate.
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