Balancing Digital Arthrodesis With Flexor Tendon Transfers And MPJ Corrections

Author(s): 
Jerome A. Slavitt, DPM, FACFAS

   The extensor tendon and capsular structures are usually not the main cause of hammertoe deformities. One will see this pathology through the flexor tendon apparatus along with plantar plate pathology.2 Therefore, those surgeons who perform just extensor capsular release or extensor tendon lengthening fixed with a K-wire usually will not have corrected the problem long-term at the MPJ. Eventually, there will be a less than satisfactory result and an unhappy patient.

   The second toe usually exhibits the greatest pathology.3 The third toe deformity may not be as significant as the second toe due to lack of influence from the hallux. The fourth toe usually exhibits a distal varus rotation. Arthrodesis and flexor tendon transfers usually accompany correction of the second and third toes. The second digit has associated pathological forces, including long second metatarsals and associated hallux valgus deformity, which contribute to transverse and sagittal plane changes. Very often, associated bunion surgery will help provide the needed space for correct digital positioning.1 Do not hesitate to discuss bunion correction with patients as it may pertain to the overall success of hammertoe corrections.

   The benefits of flexor tendon transfers with arthrodesis include maintaining correction and increasing stability of the MPJ components. This increased stability of the MPJ components assists in plantar plate repair, correction of the transverse and sagittal plane deformities, maintaining toe purchase and eliminating the positional deforming force in mallet toe deformities.4

A Guide To The Slavitt Surgical Classification For MPJ Pathology With Digital Arthrodesis

Accordingly, I would like to present a new classification for determining the appropriate surgical procedure for hammertoe correction, which involves balancing of the total digit in combination with the MPJ structures.2 The main component of this new classification is to determine the amount of capsular intervention, flexor tendon transfer position and the need for associated metatarsal osteotomy.4

Slavitt Type I — Mild Or No MPJ Pathology
Minimal capsular release
Tendon crossover at the distal segment

Slavitt Type II — Advanced MPJ Pathology
Involved capsular work
Tendon crossover at the proximal segment

Slavitt Type III — Severe MPJ Pathology/Dorsal Dislocation
Involved capsular work
Tendon crossover at the proximal segment
Tightening of medial or lateral capsule
Metatarsal osteotomy

A Step-By-Step Guide To Second Toe PIPJ Fusion With A Flexor Tendon Transfer

Once you have determined the type of classification with the corresponding surgical procedure, there is a surgical sequence that one should follow.

   In the following example, I performed a digital arthrodesis with the Digital Compression Screw (BioPro). Slightly altered sequences may be necessary if one uses alternative fixation devices.

   Begin the skin incision proximal to the head of the second metatarsal and progress distally just past the PIPJ. It is advisable to incorporate a slightly curved or lazy S incision across the MPJ to avoid the possibility of skin contracture and avoid adding unwanted deforming forces to the proximal phalanx. Identify the PIPJ and transect and reflect the extensor tendon proximally all the way to the MPJ capsule. Incise the collateral ligaments at the head of the proximal phalanx.

   In the case of fixation with the Digital Compression Screw, remove minimal distal articular cartilage from the head of the proximal phalanx to maintain length along with subchondral bone for maximum thread purchase. Remove the articular surface from the base of the intermediate phalanx. This technique is the same when one is doing an end-to-end arthrodesis with a K-wire.

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