Phalangeal Complex MSPC

The MSPC lateral release is the first step of hallux valgus correction. We perform it in each case, because we have observed that, even for mild deformities, the correction may be inadequate when the MSPC release is not performed. The lateral release has two goals (Fig. 02a): 1. To release the sesamoids from the head of the metatarsal, so that after the head is displaced laterally it will lie in its correct position above the sesamoids, which should still be in their original position.

- The drawbacks of this procedure;

- The advantages encountered with this procedure.

2. To perform the first step of hallux valgus correction by sectioning the phalangeal insertional band - without severing the metatarso-phalangeal collateral ligament -, in order to avoid over correction of the deformity.

Local Anatomy

Fig. 02a shows the local anatomy that has to be considered when accurately performing the lateral release.

Fig. 01b. The four chronological steps for hallux valgus correction.
Flexor Hallucis Longus Muscle

Fig. 02a. Lateral release: anatomy, the two goals.

1. Anatomy of the Metatarso-Sesamoidal Phalangeal Complex (MSPC). a: flexor hallucis longus tendon.

b: Phalangeal Insertional Band (PIB). c: C1 C2 adductor muscles and tendons. C3 lateral head of the flexor hallucis brevis. d: metatarsal sesamoidal suspensory ligament. LL: metatarsal phalangeal collateral ligament.

2. The scalpel first divides the suspensory ligament (d), then cuts the PIB (b): This is the first step of the hallux valgus correction and the first goal of the lateral release.

3. The total section of the suspensory sesamoid ligament (d) allows the lateral sesamoids to move plantarward, and allows the metatarsal head to lie above the sesamoids when this head is laterally displaced. This is the second goal of the lateral release.

Fig. 02a. Lateral release: anatomy, the two goals.

1. Anatomy of the Metatarso-Sesamoidal Phalangeal Complex (MSPC). a: flexor hallucis longus tendon.

b: Phalangeal Insertional Band (PIB). c: C1 C2 adductor muscles and tendons. C3 lateral head of the flexor hallucis brevis. d: metatarsal sesamoidal suspensory ligament. LL: metatarsal phalangeal collateral ligament.

2. The scalpel first divides the suspensory ligament (d), then cuts the PIB (b): This is the first step of the hallux valgus correction and the first goal of the lateral release.

3. The total section of the suspensory sesamoid ligament (d) allows the lateral sesamoids to move plantarward, and allows the metatarsal head to lie above the sesamoids when this head is laterally displaced. This is the second goal of the lateral release.

Technique and Result

Approach

Lateral mobilisation can be achieved using a medial approach, and it can be performed working either below and occasionally above the head. I prefer using a lateral intermetatarsal approach. It is easy, harmless, accurate and it allows easy access to the second metatarsal if necessary and eventually sectioning of the inter-metatarsal ligament.

The Release

The metatarso-phalangeal collateral ligament is preserved in almost every case. I believe that the valgus of the toe is a result of muscular unbalance. So cutting the Phalangeal Insertion Band (PIB) is sufficient when performing the lateral release.

Usually, the adductor tendon does not have to be completly detached from the basis of the phalanx. The head of the first metatarsal will lie in the correct superior relation with the sesamoids. On the

Phalange Hallux

Fig. 02b. Lateral release. Operative views.

1. Section of the sesamoid suspensory ligament (d) and of the phalangeal insertional band (b).

2. Checking the lateral release: ls: lateral sesamoid.

3. No overcorrection because of the preservation of the metatarsal phalangeal ligament (ll).

Fig. 02b. Lateral release. Operative views.

1. Section of the sesamoid suspensory ligament (d) and of the phalangeal insertional band (b).

2. Checking the lateral release: ls: lateral sesamoid.

3. No overcorrection because of the preservation of the metatarsal phalangeal ligament (ll).

Adductor Release Hallux Valgus

Fig. 02c. Lateral release in mild or severe deformity.

1, 2, 3. In mild deformity: The scalpel just divides the suspensory ligament (d) in order to release the sesamoids, which allows the metatarsal head to move laterally and to lie above the sesamoids. The PIB (b) remains preserved.

4, 5, 6. In severe deformity: The phalangeal insertional band (b) has to be released as far as the flexor hallucis longus (a), the tendon, becomes visible.

Flexor Hallucis Longus

Fig. 02d. The importance of the lateral release.

1. Usually (P. Diebold) the distance between the lateral sesamoid and the 2nd metatarsal does not change after the deformity correction. If the lateral release is incomplete (2), the lateral sesamoid moves laterally with the lateral shift of the head: Sometimes this does not affect the correction (3) but generally it is a factor of undercorrection (4). 5, 6, 7. Preoperatively, the lateral sesamoid is sometimes too close of the 2nd metatarsal. In this case, release of the intermetatarsal ligament is necessary (in this location this ligament is joining the 2nd metatarsal to the lateral sesamoid). This may also be useful after the metatarsal head lateral shift (7).

Fig. 02d. The importance of the lateral release.

1. Usually (P. Diebold) the distance between the lateral sesamoid and the 2nd metatarsal does not change after the deformity correction. If the lateral release is incomplete (2), the lateral sesamoid moves laterally with the lateral shift of the head: Sometimes this does not affect the correction (3) but generally it is a factor of undercorrection (4). 5, 6, 7. Preoperatively, the lateral sesamoid is sometimes too close of the 2nd metatarsal. In this case, release of the intermetatarsal ligament is necessary (in this location this ligament is joining the 2nd metatarsal to the lateral sesamoid). This may also be useful after the metatarsal head lateral shift (7).

other hand, it has been observed (P. Diebold, AFCP* 4th annual meeting, Paris 1998) that whatever the method used in hallux valgus correction, the preoperative standing dorsal plantar radiographs show that the distance between the

* AFCP : Association Fran├žaise de Chirurgie du Pied (belonging to the SOFCOT).

lateral sesamoid and the second metatarsal remains unchanged in most cases. However in preoperative cases in which the lateral sesamoid is too close to the second metatarsal, the same inter-metatarsal incision allows easy release of the first deep intermetatarsal ligament which, in this location, extends between the second meta-tarsal and the lateral sesamoid.

Second Tarsal
Fig. 02e. An excessive lateral release, generally resulting from the complete release of the metatarsophalangeal collateral ligament, results in overcorrection; repairing this ligament is then necessary (2).
Lateral Release Hallux

Fig. 02/.Lateral release - Lateral sesamoid - Medial approach.

1. Sometimes the lateral sesamoid is hypertrophied, impaired or arthritic and cannot be adequately released; in this case (B. Baudet, L. S. Weil), it may be removed.

2. The lateral release can also be made by a medial approach (L. S. Weil) with exposure between the 1st metatarsal head and sesamoids. It may be somewhat more difficult to perform and provides less exposure than the intermetatarsal approach (ex.: for the 2nd ray approach).

In very mild deformity, the PIB may almost be preserved, but the suspensory ligament must always be cut.

In large deformities, the PIB has to be entirely cut, as far as the long flexor hallucis tendon is clearly visible in the bottom of the exposure and the lateral metatarso-phalangeal ligament may also be divided but only on its plantar part, as recommended by A. Cracchiolo.

Sometimes an hypertrophied and arthritic lateral sesamoid may be removed (B. Baudet, Toulouse), which increases the MTP dorsal flexion.

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