Ligamentous Laxity Syndromes In The Foot And Ankle

Written by Bob Baravarian, DPM, FACFAS

Commonly referred to as a part of Ehlers-Danlos or Marfan syndrome, ligamentous laxity comes in many forms and many levels of instability. The most minor level is a generalized hypermobility and instability of the joints of the body. The highest levels can result in severe instability, difficulty walking and standing, and the need for assistive devices including a wheelchair. In most cases, patients presenting to a foot and ankle practice with pathology have a mild to moderate level of instability and ligamentous laxity, which causes strains and sprains of the foot and ankle, and difficulty with balance and intensive activity. 

While a medical specialist in hereditary disorders or a geneticist usually provides the definitive diagnosis of conditions that involve ligamentous laxity, patients with low-level syndromes may present to a practice with foot and ankle issues as their main complaints as those joints and the knees are the most commonly injured or sprained.¹ Patients often present with flat feet, laxity of the ankle, hypermobile rays and toes, excessive motion at the metatarsophalangeal joints, and even a knock-kneed appearance. 

Often, the complaints are mild to moderate, including giving way of the ankle and foot with activity, a feeling of instability, a tired feeling with long periods of walking, and difficulty with running and cutting sports. Those presenting in their 20s and 30s may report prior attempts with physical therapy and/or over-the-counter bracing, and even previous surgeries to correct their symptoms. 

Examination of the patient should begin with a general appearance of the body and standing posture. Often with ligamentous laxity issues, patients will stand in a genu recurvatum position due to overlocking of the knee joints for additional stability.² One may note a very stiff back position. Asking the patient to touch his or her thumb to the ipsilateral wrist is an excellent way to judge general ligamentous laxity. Furthermore, instability of the shoulders and ease of putting the hand behind the back in “back scratch” position are other signs of instability and laxity. 

When it comes to the clinical exam of the foot and ankle, start at the toes and progress proximally. Do the toes feel very flexible and easy to move medially and laterally, dorsally and plantarly? How unstable is the metatarsophalangeal joint? Is there an easy dorsal drawer test and hyperextension or hyperflexion of the toes? One will often note collapse of the midfoot and extensive talonavicular fault with unroofing on radiographic evaluation. There may be a stress syndrome and even stress fractures associated with the cuboid resulting from the arch collapse. Hypermobility of the first ray is also common, resulting in dorsal jamming of the first metatarsophalangeal joint, midfoot arthritis and hallux valgus deformity. 

At the ankle level, there is commonly easy excessive internal rotation and inversion of the ankle. Anterior drawer testing is commonly positive and assessment of the level of laxity is possible with this test. Hyperdorsiflexion at the ankle is also common in moderate and severe cases due to elasticity of the Achilles tendon and the posterior tendons. 

Diagnostic testing for Ehlers-Danlos and Marfan syndrome often involve a blood test or tissue sample. This genetic testing may provide more information about the level of hypermobility and instability, showing the level of genetic involvement and severity of the condition. Standard radiographs of the foot, ankle and possibly the knee to pelvis are helpful in overall alignment and position checks. In cases of injury, one may employ magnetic resonance imaging (MRI) to check for ligamentous and tendinous injury. A weightbearing computerized tomography (CT) scan can also be very useful prior to surgery for positional planning, to see the level of joint dislocation and view the actual joints involved in the foot and ankle malalignment. 

I find the most common presenting symptoms for ligamentous laxity and its associated conditions are arch collapse with possible hallux valgus and ankle instability with or without injury. Many foot and ankle ailments that podiatrists commonly see can also be associated with ligamentous laxity of differing levels, but arch collapse with possible hallux valgus and ankle instability are by far the most prevalent for severe ligament laxity associated with a genetic disease. It is critical to consider these syndromes when treating patients with symptoms of severe instability. Basically, if a patient presents with severe hypermobility, generalized laxity and very loose joints, a hereditary genetic laxity disorder should be a key consideration in the differential diagnosis. With these concepts in mind, here are a couple of recent case studies involving severe ligamentous laxity. 

When A Young Dancer Presents With Flat Feet And Hallux Valgus 

The first patient is an 18-year-old female with severe flat feet and a history of hallux valgus deformity since she was very young. The patient is a dancer, who has sustained some knee, ankle and foot sprains in the past, but none were severe. Her parents note that she is very flexible and “double-jointed.” 

The clinical examination revealed severe arch collapse with calcaneal valgus, a very hypermobile first ray, talonavicular instability and lateral deviation at the midfoot. She had good ankle motion and no major equinus. I referred her for ligamentous laxity syndrome testing and she was diagnosed with mild Ehlers-Danlos syndrome. 

Radiographs showed severe collapse at the noted joints and a large bunion deformity. A weightbearing CT in both uncorrected and corrected stance showed collapse mainly at the talonavicular and subtalar joints, and an elevated first ray with hallux valgus. The deformities improved in corrected stance except the hallux valgus, which was elevated with proper gait position. 

In such a case, one should avoid osteotomy procedures with or without wedging as they will often not hold up, and the deformity will return over time. In my experience, one may perform limited fusion procedures along with subsequent use of orthotics and/or bracing to correct the deformity. In this case, I performed a subtalar fusion and Lapidus bunion correction. During the case, I took care to realign the heel directly under the talus and tibia, and brought the first ray slightly below the level of the lesser rays for added stability. I also performed an intercuneiform and intermetatarsal joint 1-2 fusion to enhance stability to the midfoot region and the bunion correction. 

When A Patient Presents With Frequent Ankle Sprains And Previous Failed Attempts At Stabilization 

The second patient has a history of multiple ankle sprains over her lifetime. She sprains her ankle four to five times per year and constantly feels that the joint is unstable. The patient already has a diagnosis of Ehlers-Danlos syndrome, which is moderate in nature. She has had three prior ankle stabilizations in the form of two Brostrom-Gould procedures and a split peroneal tendon transfer to the fibula. 

All of these efforts failed and a previous consultant told the patient she needed an ankle fusion. 

The clinical examination also revealed instabilty between the tibia and fibula with dislocation at the fibular head region, which causes common peroneal nerve pain and peroneal spasm. Radiographs showed pristine joints with no arthritis and a mild flat foot position. Magnetic resonance imaging also showed the split peroneal transfer to the fibula and previous ligament repair. 

For this patient, I teamed up with a sports orthopedist to treat the problem. The sports orthopedist stabilized the syndesmosis and addressed the proximal tibiofibular instability with two TightRope (Arthrex) fixations. The orthopedist took care to decompress and protect the common peroneal nerve. At the ankle level, there are two options available. It is critical to not use the patient’s own tissue. There is hyperelasticity to these structures so the tissue is not ideal. Instead, one may employ either cadaver tendon or an InternalBrace (Arthrex) system. I prefer the cadaver tendon. In my experience, the cadaver tendon stabilizes the anterior talofibular and calcaneofibular ligaments very well. 

I drilled and fixated a full cadaver peroneal tendon to the talus. Then I passed that tendon through a drill hole in the fibula and fixated it under tension to the fibula in order to create the anterior lateral ligament structure. After passing the tendon into the calcaneus deep to the peroneal tendons, I fixated it in the calcaneus under tension with a second fixation device. 

The patient had an uneventful recovery and is able to walk without pain. In fact, she returned for the same procedure on the contralateral limb two years later. 

In Summary 

It is critical to consider ligamentous laxity when dealing with patients who have hypermobility issues, severe joint laxity and collapse. In such cases, genetic testing and blood work may help diagnose the underlying condition. Treatment should mainly be through fusion of non-essential joints such as the subtalar joint and tarsometatarsal joints in the midfoot with ligamentous stabilization of essential joints if possible. 

If ligamentous repair of unstable joints is a consideration, the surgeon should avoid direct repair of the patient’s own ligaments or use of the patient’s own tendon for transfer and stabilization procedures as they may be of poor quality. Cadaver tendon can be a useful alternative to add stability. 

Dr. Baravarian is an Assistant Clinical Professor at the UCLA School of Medicine. He is the Director and Fellowship Director at the University Foot and Ankle Institute in Los Angeles. Dr. Baravarian discloses that he is a speaker and shareholder with OSSIO and Crossroads Extremity Systems. 

References

1. Sueyoshi T, Emoto G, Yuasa T. Generalized joint laxity and ligament injuries in high school-aged female volleyball players in Japan. Orthop J Sports Med. 2016;4(10):2325967116667690. 

2. Singh AP. Genu recurvatum or knee hyperextension. Bone and Spine. As one can see in this photo, a good test of possible ligamentous laxity is to have the patient attempt to touch his or her thumb to the wrist.In this photo, one can see an inversion test showing extreme laxity of the ankle in an uninjured patient.Available at: https://boneandspine.com/genu-recurvatum/ . Accessed October 9, 2020.