Jonathan T. Deland
DEFINITION
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 actually is 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 1).
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 2).
Because of location, failure of the superomedial portion should result 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 3).
PATHOGENESIS
Spring ligament failure is due most commonly 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, and it can be associated with an acute episode.
Although spring ligament failure is associated with a preexisting flatfoot, it commonly 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 compared with 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 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 most commonly present with medial pain, which usually is associated with the posterior tibial tendon rather than the spring ligament, although isolated traumatic injuries to the spring ligament do occur. If enough deformity has occurred, pain occurs in the lateral hindfoot from impingement secondary to subluxation in the triple joint complex.
FIG 1 • Anatomy of the spring ligament complex (dorsal view with talar head removed). Note the location of the superomedial and inferomedial positions. The superomedial portion is medial to the posterior tibial tendon. It originates from the superomedial aspect of the sustentaculum tali and anterior facet of the calcaneus to insert on the medial navicular adjacent to its articular surface.
FIG 2 • Anatomy of the spring ligament complex seen from the plantar view. 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 3 • Because of its location, failure of the superomedial portion should result in primarily medial migration of the talar head, whereas failure of the inferior portion results in primarily plantar migration. Most commonly, the migration is both medial and plantar. A. MRI scan with severe degeneration and attenuation (grade III/IV) of the superomedial portion of the spring ligament complex. B. MRI with a severely frayed and degenerated (grade IV/IV) plantar portion of the spring ligament complex.
Depending on the presence and amount of deformity, the patient may or may not notice weakness or collapse in the arch. Most patients do 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 may also include the following steps:
Palpate the medial talonavicular joint and posterior tibial tendon to evaluate swelling;. Acute and subacute tears.
Palpate the tendon versus the joint for tenderness. Tenderness on the tendon indicates tendon involvement and often masks tenderness from a tendon 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 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. For grades I through IV, tendon transfer may be required.
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 4A).
On the lateral view, plantar migration of the talar head in relation to the navicular can be checked (FIG 4B). The lateral talometatarsal angle, while a useful measurement, includes deformity at the naviculocuneiform and metatarsaltarsal joints.
Radiographs are not diagnostic tools but are helpful in assessing deformity—as long as the patient is standing and the radiographic technique allows AP and lateral views with full weight bearing.
An MRI scan visualizing the spring ligament complex 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 3).
DIFFERENTIAL DIAGNOSIS
Degeneration or tear of the posterior tibial tendon without spring ligament failure
Congenital flatfoot
FIG 4 • The lateral and AP radiographic views of the foot should be obtained with the patient standing and told to let the arch sag. A. Standing lateral view of the foot showing a flat medial longitudinal arch with an increased talometatarsal angle on the lateral view. B. The AP view shows increased uncoverage of the medial talar head. These findings are characteristic–but not diagnostic–of a flatfoot associated with spring ligament pathology. Standing AP radiograph of the ankle also should be performed to rule out valgus deformity at the ankle joint.
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. It also may 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 may be used.
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 and degree of injury to the spring ligament place them at high risk for progressive deformity.4
Relative contradictions 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 ligament 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.
Surgeons should be prepared to deal with large tears or significant tissue loss in the spring ligament complex.
This may necessitate the use of tendon graft, possibly allograft tendon.
Possible Achilles contracture should be assessed.
Correction of the foot alignment should be considered an integral part of the procedure.
Remember that repair or reconstruction of the spring ligament has yet to be shown to correct bony malalignment and that a flatfoot deformity places strain on the spring complex.
Whether spring ligament reconstruction adds to alignment correction when bony procedures are being performed is debatable. In our experience, however, 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 by the osteotomies.
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.
Lateral hindfoot incisions are used as necessary for calcaneal osteotomies.
TECHNIQUES
PRIMARY SUPEROMEDIAL SPRING LIGAMENT REPAIR
Primary repair rather than reconstruction is done when good tissue for repair is present and ends can be well apposed. Foot deformity is corrected at the same time.
Figure 8 or horizontal mattress sutures are placed to appose both ends of the ligament with the foot in neutral position. Knots are placed to avoid impingement against the posterior tibial tendon (TECH FIG 1).
If the ligament cannot be apposed with the foot in neutral or the tissue is attenuated, then reconstruction of the ligament is necessary for large tears. The reconstruction is performed together with osteotomies to correct bony alignment.
TECH FIG 1 • Operative photograph of repair of spring ligament. This repair was accompanied by a medial slide calcaneal osteotomy to address the deformity. Figure 8 or horizontal mattress sutures are placed to appose both ends with the foot in neutral position. Knots are placed to avoid impingement against the posterior tibial tendon.
SUPEROMEDIAL SPRING LIGAMENT RECONSTRUCTION
Tendon graft is used to replace insufficient ligament tissue and block medial migration of the talar head.
Achilles allograft is used most commonly, although peroneus longus can be used if both the longus and brevis are in good condition and overcorrection of bony realignment is avoided.
Because the superomedial spring ligament blends in with the anterior deltoid ligament, which also can be attenuated, reconstruction of the anterior deltoid and superomedial spring ligaments is commonly performed together (TECH FIG 2A).
Bone tunnels in the navicular and tibia are used to create a ligament path to support the medial talar head (TECH FIG 2B).
The navicular tunnel is placed from dorsal to plantar/medial over a cannulated drill. The graft is to exit plantar medially and cross the medial talar head.
A tibial tunnel beginning at the most inferior midportion of the medial malleolus tip is used.
The tibial tunnel exits laterally 5 to 9 cm above the ankle joint line.
A lateral longitudinal incision over the fibula is used to access the lateral tibia and fibula.
TECH FIG 2 • A. Diagram of superomedial spring ligament reconstruction. The repaired ligament crosses the medial aspect of the talar head to block medial migration of the head. An alternative to the tibial drill hole is a drill hole in the medial talar neck. Because the superomedial spring ligament blends in with the anterior deltoid ligament, which also can be attenuated, reconstruction of anterior deltoid and superomedial spring ligaments is commonly performed together. B. Exit hole of the graft at the inferior navicular and corresponding entrance hole into the tibia at the midportion of the tip of the medial malleolus. The navicular hole is drilled from dorsal to plantar and the tibial hole from the medial malleolus out the lateral tibia above the ankle. Bone tunnels in the navicular and tibia are used to create a ligament path to support the medial talar head.
Given the size of the foot, the largest drill hole in the navicular is used, so a large tendon graft (6–9 mm) is possible.
The graft is fixed at the navicular first and tensioned via the lateral ankle incision. The graft is tightened with the talonavicular joint in neutral to slight adduction.
Fixation of the graft is via whipstitch using no. 2 nonabsorbable suture tied at each end, to a dorsal screw in the navicular and a lateral screw on the fibula.
With the navicular end tied down first, the foot is placed in neutral to slight adduction and the ligament graft tensioned and tied down laterally.
Alternative fixation with interference screws can be used, but the fixation may not be as strong with this technique in the tibia.
For large abduction deformities (ie, >30 degrees of talar head uncoverage), spring ligament reconstruction alone cannot be expected to hold correction and should, based on my experience, be used as a supplement to a lateral column lengthening procedure.
Lateral column lengthening—as minimal as possible—is done to place the talonavicular joint in neutral alignment.
The lateral column lengthening procedure should allow a minimum of 5 degrees of passive eversion to avoid excessive lateral tightness and should be tested in the operating room by everting the foot.
An alternative to the tibial tunnel is a tunnel in the proximal talar neck with fixation using an interference screw.
INFERIOR SPRING LIGAMENT RECONSTRUCTION
Tendon grafting also is used, but for deformity that is primarily plantar migration of the talar head.
Graft is used to replace attenuated or degenerated tissue in combination with bony procedures to correct flatfoot deformity (TECH FIG 3A).
Bone tunnels are used in the navicular and calcaneus (TECH FIG 3B).
The navicular tunnel is made from dorsal to plantar medial.
The calcaneal tunnel is drilled from underneath the distal medial and anterior facets and exits out the lateral calcaneus. The lateral exit point is exposed using the standard oblique incision for a posterior calcaneal osteotomy.
The graft is fixed first at the navicular, with the foot placed in 5 degrees of inversion with the calcaneus out of valgus (neutral). Calcaneal osteotomy is commonly performed and is fixed before the calcaneal drill hole is made and the graft is passed through.
Fixation of the graft is with nonabsorbable suture sewn in to the ends of the graft and tied down to screws in the dorsal navicular and lateral calcaneus. Alternative or supplemental fixation is done with interference screws.
The calcaneus cannot be left in valgus, or excessive strain on the graft will result.
TECH FIG 3 • A. Diagram of plantar spring ligament reconstruction with the graft extending from the drill hole in the navicular to the calcaneus. Graft is used to replace attenuated or degenerated tissue in combination with bony procedures to correct flatfoot deformity. B. Navicular exit hole and calcaneal entrance for the graft. A drill hole is made dorsal (dorsal portion not shown) to plantar in the navicular and medial to lateral (not shown) in the calcaneus. Bone tunnels are used in the navicular and calcaneus.
COMBINED SUPEROMEDIAL AND PLANTAR SPRING LIGAMENT RECONSTRUCTION
Combined superomedial and plantar spring ligament reconstruction is done for patients with considerable abduction of the talonavicular joint and plantar migration of the head.
Two tendon grafts or a large tendon graft that is split at the plantar medial navicular tunnel is used (TECH FIG 4).
The navicular tunnel is made as large as possible without fracturing the navicular to enable placement of large grafts. If allograft tendon is used, Achilles allograft with a bone block in the navicular tunnel is suggested (TECH FIG 5).
The talonavicular joint is pinned in the corrected position (ie, 5 degrees of inversion and the calcaneus in neutral) after any bony procedures are fixed.
The tendon grafts are then tensioned and fixed at the lateral calcaneus and fibula.
Reconstruction with combined techniques is intended not to replace bony procedures but to supplement them when considerable tissue loss in the spring ligament complex is noted and correction of bony alignment has been gained at or near neutral position.
Commonly, a posterior osteotomy and, often, lateral column lengthening are performed.
TECH FIG 4 • A. Diagram of combined spring ligament complex reconstruction shows combined superomedial and plantar reconstruction. Two tendon grafts or a single large tendon graft that is split at the plantar medial navicular tunnel is used. B. Diagram of alternative combined spring ligament reconstruction using the peroneus longus left attached to first metatarsal base (shown) or free graft from the navicular plantar hole to the calcaneus and back to the navicular dorsal hole (not shown). Two tendon grafts or a large tendon graft that is split at the plantar medial navicular tunnel is used.
TECH FIG 5 • Drill holes for the combined spring ligament complex reconstruction with the graft exiting the plantar navicular and going into drill holes at the calcaneus. The navicular tunnel is as large as possible without fracturing the navicular, to enable placement of large grafts. If allograft tendon is used, Achilles allograft with a bone block in the navicular tunnel is suggested.
POSTOPERATIVE CARE
Touch-down weight bearing is allowed at 2 weeks and progressive weight bearing from 8 to 10 weeks.
In reliable patients, a cast boot can be used instead of a cast beginning at 6 weeks.
Full weight bearing without a boot is allowed at 12 to 16 weeks.
Active inversion and eversion can be started at 6 weeks.
OUTCOMES
Because spring ligament reconstructions are commonly combined with other procedures, it is difficult to define the contribution of these procedures to patient outcomes, and no reports have done so until recently.
In our experience, spring ligament reconstruction does contribute to correction of deformity but only when most of the correction has been achieved through the bony procedures. I would use the superomedial spring ligament reconstruction for those feet with more of an abduction deformity and the plantar for those with more of a plantar sag deformity at the talonavicular joint. The superomedial may adequately correct combined deformity; if not, use the combined superomedial and spring ligament reconstruction.
COMPLICATIONS
Failure of the graft can occur, particularly when a soft tissue procedure is used to try to correct large amounts of deformity without adequate bony correction of deformity.
Failure of fixation of the graft. Interference screws are helpful, but the fit must be tight and tunnels must be made at somewhat of an angle to avoid straight pullout of the graft.
Overcorrection with lateral weight bearing can occur, either with a medial slide osteotomy or, more commonly, if lateral column lengthening is used. Normal eversion motion should be maintained.
The heel should be in alignment with the lower leg (not in varus), and passive eversion into at least 5 degrees should be present after all the procedures are fixed.
The lateral column should not feel tight on rangeof-motion testing in the operating room after the bony correction—eversion should be present.
REFERENCES
· Davis WH, Sobel M, Deland JT, et al. The gross, histological and microvascular anatomy and biomechanical testing of the spring ligament complex. Foot Ankle Int 1996;17:95–102.
· Deland JT. The adult acquired flatfoot and spring ligament complex, pathology and implications for treatment. Foot Ankle Clin 2001;6: 129–135.
· Deland JT, de Asla RJ, Sung I-H, et al. Posterior tibial tendon insufficiency: Which ligaments are involved? Foot Ankle Int 2005;26: 427–435.
· Deland JT, Page A, O'Malley MJ, et al. Posterior tibial tendon insufficiency. Results at different stages. HSS J 2006;2:157–160.
· Hiller L, Pinney S. Surgical treatment of acquired adult flatfoot deformity: What is the state of practice among academic foot and ankle surgeons in 2002? Foot Ankle Int 2003;24:701–705.
· Pinney SJ, Lin SS. Current concept review: acquired adult flatfoot deformity. Foot Ankle Int 2006;27:66–75.