What is a peroneal orthosis?

The peroneal nerve (“fibular nerve”) is responsible for controlling the lifting of the foot and toes. Muscle weakness and paralysis of the foot lifting muscles is known as “peroneal nerve palsy”. The foot can no longer be fully lifted when walking and becomes an obstacle when walking. At the onset of the symptoms, there is repeated “stumbling” or “getting stuck” on the tip of the foot. In addition to muscle weakness (paresis), increasing muscle tension (spasticity) can also lead to a predominance of foot drop and thus to a “pointed foot position”. In this constellation, too, the tip of the foot becomes an obstacle to walking and running.

A peroneal orthosis can reduce the drop foot or pointed foot and improve walking. In the current state of medicine, it is not yet realistic to restore muscle function with medication. The focus is therefore on stabilizing the muscle weakness with a peroneal orthosis. A peroneal orthosis is a “splint” for the foot that compensates for weakness in the foot lifting muscles. This orthosis consists of a holding plate on the sole of the foot (which prevents the forefoot from dropping), which in turn is connected to a holding shaft on the lower leg via a bracket (or an adjustable joint). The peroneal orthosis is usually made of carbon in order to achieve a high degree of stability and flexibility at a low weight. Carbon is a modern material that has these desired properties (low weight, high load-bearing capacity and defined elasticity). In addition to carbon (for the basic framework), foams and Velcro fasteners are used to fix the orthosis to the lower leg and foot. Other materials, e.g. individually molded plastics or metal applications, can also be used in cases of severe peroneal nerve palsy.

Spasticity of the foot (with a sitting foot position and contracture of the Achilles tendon) can also place special demands on a peroneal nerve palsy. In the case of high spastic muscle tension, it may be necessary to make the orthosis from materials that have greater stability and are able to offer greater resistance to the muscle pressure (caused by the spasticity). In certain constellations, it may be necessary to incorporate “joints” into the orthosis in order to allow the foot angle to be adjusted and thus adapt the orthosis to the changing contracture. In special situations, it may be possible to reduce an existing tendon shortening by adjusting the angle of the orthosis and move the pointed foot back into a regular position (“redression”). This correction can only be achieved through long-term and continuous application of light pressure (over a period of weeks and months).

ALS presents the particular challenge of a progressive disease, resulting in altered conditions throughout the course of the disease. Correction of contractures is therefore only realistic and desirable in exceptional cases. For the majority of peroneal orthoses, compensating for deficits in the drop foot and stabilizing the ankle joint as well as improving walking are realistic treatment goals.

It is not advisable to use “simple” plastic orthoses, as the stability and load-bearing capacity of this material is usually insufficient. Treatment with a plastic orthosis (or traction bandages with Velcro fasteners on the lower leg and footwear) may only be suitable in the case of very mild foot drop. Most peroneal orthoses can be worn with regular footwear. Due to the wide range of peroneal orthoses available and the individual physical requirements for wearing a peroneal orthosis, it is recommended that a medical supply retailer specializing in the care of ALS patients provides the fitting.