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Scapulothoracic Fixation Orthosis for Facioscapulohumeral Dystrophy

S. Alsancak
H. Altinkaynak
H. Kinik

ABSTRACT

A 20-year-old male patient with bilateral facioscapulohumeral dystrophy was admitted to the Ankara University Department of Prosthetics and Orthotics for orthotic treatment. In the physical examination, the patient's bilateral limitation in active glenohumeral range of motion, decrease in muscle strength around the shoulder, and marked scapular protraction and elevation were present. A scapulothoracic fixation orthosis was designed in our laboratory to reduce scapular winging and thus improve the patient's active range of motion of the shoulder. This new orthosis was compared with other orthoses for scapular winging and found to be superior in terms of active shoulder range of motion and muscle strength.

Keywords:Facioscapulohumeral dystrophy, scapular winging, scapular orthosis

Facioscapulohumeral dystrophy (FSHD) is an autosomal-dominant inherited muscular dystrophy that affects the facial, shoulder girdle, and, in the late phase, lower-extremity muscles. Common age of onset is between 15 and 35 years, and the disorder has a slow progression.¹,² The greatest functional disability is the inability to abduct and flex the arm at the glenohumeral joint. Scapulothoracic fusion or fixation of the scapula to the ribs or the dorsal spine with some tethering sling is the preferred method of treatment for shoulder protraction and scapular winging associated with this disorder.^3,4,5

In 1984, Fiddian and King⁴ classified scapular winging in FSHD according to etiology and clinical picture. Clinically, scapula alata deformity is static or dynamic. The static form is expressed as a fixed deformity in the shoulder girdle, the ribs, or the thoracic spine. In the dynamic form, the scapula can be stabilized passively in a normal position without any obstruction. Scapular winging may be assigned to one of four etiologic classifications: Type I, nerve; Type II, muscle; Type III, bone; or Type IV, joint.⁴

Few modalities delay the occurrence of secondary deformities associated with winging and support the shoulder girdle for better range of motion. These include sling systems such as a cloverleaf sling supported with scapular pads,⁶ a spica brace,⁷ a scapula alata brace,⁸ canvas shoulder braces with steel bars at each side of the back functioning as a scapular orthosis,^9,10 and a serratus anterior restraining brace¹¹ (Fig. 1 ). In this study, a scapulothoracic fixation orthosis (STFO) that prevents protraction, elevation, and rotation of affected scapula in Type II FSHD is described. The results were also compared with other previous orthoses.

Method

Patient

A 20-year-old male patient with FSHD was referred to the Ankara University Department of Prosthetics and Orthotics for an orthosis in June 1999. During the patient's clinical evaluation, muscle- strength test results for face, neck, trunk, and upper and lower extremities and active range of motion scores for both shoulders were recorded. Range of motion was measured with the Rippstein plurimeter.¹² The results were evaluated according to the criteria of Kendall et al.¹³ Muscle-strength scores were recorded between 0 and 5 according to Daniels and Worthingam¹⁴ criteria.

Active glenohumeral joint motion was measured as follows: flexion, 77 degrees R/80 degrees L; abduction, 80 degrees R/90 degrees L; internal rotation, 20 degrees R/30 degrees L; and external rotation, 55 degrees R/70 degrees L (Table 1 ). Hyperextension was impossible in both shoulders. He had a full passive glenohumeral range of motion. When he was standing with his arms beside him in a resting position, we measured his scapular protraction to be 25 degrees R/10 degrees L and elevation of 15 degrees R/30 degrees L. Active flexion further increased the protraction and rotation of the scapulae (Fig. 2 ).

Muscle tests of the shoulder area revealed following information:

1. Glenohumeral muscles: flexion, 2+ R/3- L; hyperextension, 2- R/2+ L; abduction, 3 R/3 L; horizontal adduction, 2+ R/3- L; internal rotation, 2+ R/3 L; and external rotation, 2 R/3- L (Table 2 ).
2. Scapulothoracic muscles: scapular abductors, 3 R/4 L; elevators, 3+ R/4 L; adductors, 2- R/2+ L; depressors, 1 R/1 L; and rhomboids, 2 R/3 L.
3. Arm muscles: flexors, 3+ R/3 L; and triceps, 4 R/3+ L.
4. Facial muscles: 4.
5. Neck muscles: flexors, 3; and extensors, 3.
6. Trunk muscles: flexors, 2; and extensors, 3.
7. Lower extremity: 4.

A scapulothoracic fixation orthosis was designed for this patient in our laboratory. The specifications of the orthosis are described in the following sections.

Material.

The following materials were used in the orthosis: low-density polyethylene (4-mm thickness), polyform (5-mm thickness), Plastazote (10-mm thickness), Velcro straps (30- and 45-mm widths), diolene nonelastic webbing bands (35- and 50-mm widths), and two roll loops.

Dimensions.

The orthosis is designed as a jacket that covers the thorax and both shoulders. The lower border is the subcostal margin.

Principle.

The polyethylene jacket has an anterior opening. Two scapular cups allow scapulothoracic fixation. Anteriorly, the jacket has a window on each side (A and B). Polyform pads are placed on the subcostal margin (Fig. 3 ).

Forces and Effects.

Fourteen forces act on the patient through the orthosis on both sides. The forces on the right side are denoted as A and those on the left side are indicated as B. F1_a and F1_b act on the subclavicular region, F2_a and F2_b act on ribs VII and VIII, F3_a and F3_b act on the scapulae (transverse forces are F3_ax and F3_bx; oblique forces are F3_ay and F3_by), F4_a and F4_b act on the shoulders, and F5_a and F5_b act on the subcostal region (Fig. 3 ). In addition, from the right shoulder anteriorly to the left lateral subcostal region, F6_a1 and F6_b2 forces act on the patient's body; and from the left shoulder anteriorly to the right lateral subcostal region, F6_b1 and F6_a2 forces act on the body (Fig. 4 ).

The principle actions of these forces are as follows. F3_ax and F3_bx forces act against scapular protraction, and F3_ay and F3_by forces act against rotation. F1 and F2 forces are counterforces to the F3 force. F4_a and F4_b forces act against elevation of the scapulae. F5_a and F5_b forces prevent upward motion of the orthosis on the trunk. F6 force acts against the rotation of the orthosis around the trunk axis. The A and B holes in the device are designed to decrease the constrictive effect of F3 force and to allow thoracal anterior motion and expansion.

There are four holes between the mobile scapular cups (Fig. 5 ). Two of them lie vertically on the base of an equilateral triangle. The other two holes lie obliquely and meet on the apex of the triangle. Transverse (F3_ax and F3_bx) forces and oblique (F3_ay and F3_by) forces act through V-shaped straps that are held to the base of the triangle (short band) and to the apex (long band) with Velcro.

Results

We assessed the efficacy of the scapulothoracic fixation orthosis (STFO) by having our patient use three other orthoses designed for the winging of scapulae, including a Marin orthosis with scapular pads (MO), a canvas orthosis with steel bars (CO), and a Johnson orthosis with metal bars (JO). The results of this comparison are reported in Table 1 .

The STFO was found to be the most effective in restoring glenohumeral motion, followed by the JO, the CO, and the MO. Semirigid orthoses were found to be more effective than orthoses with slings. The STFO also eliminated scapular protraction and elevation (Fig. 6 ).

Muscle-strength scores increased with scapular stabilization on the thorax. Glenohumeral muscle-strength scores with and without orthoses are compared in Table 2 . The STFO was found to be the most effective, followed by the JO, the CO, and the MO.

Overall, the STFO increased the patient's glenohumeral range of motion and relative muscle strength. Activities of daily living were more comfortable for the patient; his working period of the shoulder and arm without weakness was prolonged; and he found lifting and pushing heavy objects and taking objects from upper shelves to be easier with the orthosis.

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15. SERAP ALSANCAK, PhD, is an associate professor with the Department of Prosthetics and Orthotics, Ankara University, Ankara, Turkey.
16. HAYDAR ALTINKAYNAK, MSc, is a mechanical engineer with the Department of Prosthetics and Orthotics, Ankara University, Ankara, Turkey.
17. HAKAN KINIK, MD, is an orthopedic surgeon with the Department of Orthopedics and Traumatology, Ibn-i Sina Hospital, Ankara University, Ankara, Turkey.