Spring Ligament Reconstruction

Spring ligament failure consists of lengthening or disruption of the spring ligament complex resulting in subluxation at the talonavicular joint.

Spring ligament failure is commonly associated with considerable degeneration of the ligament. The ligament complex may have tears or large defects, or it may just be attenuated.

Tears most commonly occur in the superomedial portion of the spring ligament complex, adjacent to the posterior tibial tendon, but can occur in the inferior portion as well.

It is necessary to look at the alignment of the foot to determine how to treat failure in the spring ligament. If a flatfoot is present with increased heel valgus or abduction (or both) through the midfoot and there is a full tear of more than 30% of the ligament or severe attenuation, the risk of progression of deformity is high.

ANATOMY

The spring ligament is actually a complex of ligaments composed primarily of a superomedial portion and an inferior portion. The deltoid ligament blends in with the superomedial portion.¹

The superomedial portion is medial to the posterior tibial tendon. It originates from the superomedial aspect of the sustentaculum tali and the anterior facet of the calcaneus to insert on the medial navicular adjacent to its articular surface (FIG 1A).

The inferior portion originates from the notch between the anterior and medial calcaneal facets. It inserts on the inferior surface of the midnavicular, just lateral to the insertion of the superomedial portion of the spring ligament (FIG 1B).

Because of location, failure of the superomedial portion results in primarily medial migration of the talar head, whereas that of the inferior portion results in primarily plantar migration. Most commonly, the migration is both medial and plantar (FIG 2).

PATHOGENESIS

Spring ligament failure is usually due to the repetitive stresses of a flatfoot causing increased strain on the medial ligaments of the foot.

Failure most often occurs in the setting of a degenerated ligament, but it can be associated with an acute episode.

Although spring ligament failure is associated with a preexisting flatfoot, once spring ligament failure occurs, it frequently results in progressive deformity of the foot at the talonavicular joint and hindfoot. Because the foot progresses out from under the talar head dorsally and laterally, the talar head migrates medially and plantarly in relation to the rest of the foot.

NATURAL HISTORY

Failure of the spring ligament complex most commonly occurs along with posterior tibial tendon insufficiency.³

With or without tendon insufficiency, spring ligament failure places the patient at risk for progressive subluxation at the talonavicular joint. If subluxation is already present, progression of the subluxation is highly likely.⁴

Progressive subluxation at the talonavicular joint eventually can cause enough deformity in the triple joint complex (ie, the talonavicular, calcaneocuboid, and subtalar joints) to result in lateral impingement and pain in the hindfoot, a collapsed foot.

PATIENT HISTORY AND PHYSICAL EXAMINATION

Patients present with medial pain, which usually is associated with the failure of the posterior tibial tendon rather than the spring ligament. Isolated traumatic injuries to the spring ligament do occur but are uncommon. Later in the course of the condition, if enough deformity has occurred, pain occurs in the lateral hindfoot from impingement secondary to subluxation in the triple joint complex.

Depending on the presence and amount of deformity, the patient may or may not notice the weakness or collapse in the arch. Most patients notice some weakness.

Physical examination should evaluate the posterior tibial tendon and alignment of the foot with the patient letting the arch sag fully when standing.

The posterior tibial tendon should be palpated for tenderness. Inversion strength should be tested from an everted position to a plantarflexed and inverted position.

Clinical alignment should be checked for midfoot abduction and height of the arch as noted on the frontal standing view. The degree of heel valgus is assessed from the posterior standing view.

Physical examination should also include the following steps:

Palpate the medial talonavicular joint and posterior tibial tendon to check any tenderness.

Tenderness on the tendon indicates tendon involvement and often masks tenderness from a ligament tear.

Evaluate range of motion. Compare the arc of motion (maximum eversion to maximum inversion) to the other foot. The arc of motion may be categorized as follows: full, some inversion present, motion only to neutral, or joint contracted in eversion. The joint must be mobile into inversion for tendon repair or reconstruction.

Evaluate inversion strength. Start with the foot in eversion and have the patient push against the examiner’s hand to inversion and plantarflexion. Do not be misled by combined dorsiflexion and inversion strength, which is from the anterior tibial tendon and muscle.

IMAGING

The anteroposterior (AP) and lateral foot radiographs should be obtained standing with the patient told to let the arch sag. An AP standing radiograph of the ankle also should be performed to rule out valgus deformity at the ankle joint.

On the AP view of the foot, abduction at the talonavicular joint can be measured with the talonavicular uncoverage angle (ie, the amount of talar head not covered by the navicular; FIG 3A).

On the lateral view, plantar migration of the talar head in relation to the navicular can be checked (FIG 3B). The lateral talometatarsal angle, although a useful measurement, includes deformity at the naviculocuneiform and metatarsal–tarsal joints.

Radiographs are not diagnostic tools but are helpful in assessing deformity—as long as the patient is standing, letting the arch sag with weight bearing.

A magnetic resonance imaging (MRI) scan visualizing the spring ligament complex of the ligament tear and amount of degeneration can indicate the amount of degeneration or tear in the complex and is useful for diagnosis if it is of good quality and if it is read by an experienced examiner (see FIG 2).

DIFFERENTIAL DIAGNOSIS

Degeneration or tear of the posterior tibial tendon without spring ligament failure

Congenital flatfoot

NONOPERATIVE MANAGEMENT

Nonoperative management is particularly appropriate for those patients for whom the tear and alignment are thought to have a low probability of progression. These are patients with no or minimal flatfoot deformity and not a large tear. Conservative treatment may also be used for those patients who wish to delay surgery, but they must be informed of the risk of progression of deformity.

Nonoperative management consists of support for the medial longitudinal arch with one of the following devices. (They do not at all guarantee stopping the progression of deformity.)

A removable boot is helpful for initial management. A medial longitudinal arch support inside the boot is advised.

A short, articulated ankle–foot orthosis is less cumbersome and allows ankle motion with a customized arch support.

A custom orthotic with a medial longitudinal arch support and medial heel wedge is the least cumbersome but also provides the least support.

A solid leather gauntlet or Arizona brace allows minimal motion. It is best for those patients with considerable deformity and limited function.

Patients receiving conservative care should be monitored for progression of flatfoot deformity.

SURGICAL MANAGEMENT

Surgery is the best choice for patients with progression of flatfoot deformity associated with failure of the spring ligament complex or patients whose alignment places them at high risk for progressive deformity.⁴

Relative contraindications include medical conditions that adversely affect healing such as diabetes, corticosteroid use, and neuropathy.

Reconstruction of the spring ligament is not useful in those patients with rigid hindfoot deformity and is not necessary in those patients with small tears or good correction of alignment with bony procedures.

Preoperative Planning

Standing clinical alignment and standing AP and lateral radiographs of the foot and ankle should be carefully reviewed to plan for correction of alignment as well as repair or reconstruction of the spring ligament. A heel alignment (Saltzman view) is also helpful to assess amount of calcaneal valgus.

Surgeons should be prepared to deal with large tears or significant tissue loss in the spring ligament complex.

This will often necessitate the use of tendon graft, most commonly allograft tendon.

Possible Achilles contracture should be assessed.

Correction of the foot alignment should be considered a critical part of the procedure.

Remember that repair or reconstruction of the spring ligament on its own has yet to be shown to correct bony malalignment and that a flatfoot deformity places strain on the spring complex.

Alignment correction is achieved by spring ligament reconstruction if osteotomies are performed at the same time and the foot is placed near the corrected position (>50% corrected) by the osteotomies. Although spring ligament reconstruction cannot give correction on its own, it can add correction to what is achieved by the bony procedures.

Spring ligament reconstruction is the most logical choice for large tears and is performed along with bony realignment of deformity.^2,5,6

Positioning

The patient is placed in the supine position with a bolster under the greater trochanter so that the lower leg is neither internally or externally rotated. This allows good access to both sides of the foot.

In this position, exposure of the spring ligament, posterior tibial tendon, and lateral hindfoot is possible.

Approach

A medial incision is made from the tip of the medial malleolus to 2 cm distal to the navicular to inspect the posterior tibial tendon and expose the spring ligament complex by retracting the tendon.