A Modular Orthosis for Brachial Plexus Lesions

M. WARDLOW, F.B.LS.T., A.M.B.I.M.


Economic factors have forced governments to increase the tax revenue on petroleum spirit, and as a direct consequence more and more young people are taking to two wheels instead of four as a cheaper means of travel. Increased mileage and less expensive road fund licence, coupled with the thrills and excitement and the independence of motor cycling and, to some extent, the need to be accepted as "one of the pack," snare the unsuspecting victim in a trap that very often leads to misery and heartache.

In England, where legislation now makes it an offence for motor cyclists not to wear protective headgear, the incidence of patients with brachial plexus injuries has greatly increased in clinics around the country. Whereas before legislation the mortality rate was fairly high, many more cyclists now survive because of this one item of protection. Statistics indicate that the majority of brachial-plexus-lesion cases seen in clinic are young men in their late teens and early twenties.

The brachial plexus is situated in the lower portion of the posterior triangle of the neck, and it is easy to visualize the devastating consequences connected with injury to this region when the head is forced laterally at the moment of impact. It is this traction injury, when the neck is pulled away from the arm and vice versa, that can stretch and damage the nerve within the nerve sheath, cause a rupture in the neck, or avulse the nerve from the cord. It is the last injury for which the orthosis is most useful.

Paralysis can strike one muscle, any one of a group of muscles, different muscles in different groups, individually or collectively, producing a very significant loss of function. A patient with a paralysed arm will, of necessity, become one-handed very quickly, and if the nondominant limb is affected, he will become single-handed in three to four weeks.

In the past, one of the major obstacles has been the delays to which the physician and the patient have been subjected in awaiting a definitive orthosis. Such delays are to a certain extent encountered today, but mainly because of other concurrent injuries which are often as horrendous as the prognosis, necessitating a prolonged hospitalization.

Of paramount importance was the need to speed up the process whereby the clinical assessment and delivery of an appliance could be foreshortened. What was needed was an instant orthosis an orthosis which would lend itself to adaption and by necessity be modular in concept.

In the early 1960's, Dr. R. Redhead 1 , who was then working in the Research Department of the Department of Health and Social Security at the Limb Fitting Centre, Queen Mary's Hospital, Roehampton, and fellow colleagues, produced the first appliance known as the "Roehampton Flail Arm Splint." It is a credit to the

design that the orthosis changed very little until February 1977, when at Dr. C. B. Wyn-Parry's 2 request, the manufacturers 3 updated some of the modules. The adaptions now available have enabled the orthosis to be used more effectively in the rehabilitation of the patient.

Technical Description

The basic appliance is supported on the patient by a friction-faced metal waistband, and adjustment around the waist is obtained by the use of nylon straps with Velcro fastening (Figure 1-A. , Figure 1-B. , and Figure 1-C. ). Rising from the centre of the waistband to the posterior region of the axillary fold, a telescopic tube forms the support from which the upper steel is hinged. The telescopic adjustment of this support allows for individual fitting of the patient. Lateral rotation of the appliance is obtained by the tubular construction of the support, and the maximum internal rotation can be limited. A flat return spring is fitted internally to the inner tube to ensure that, when laterally rotated, the appliance will return to the set position. At the proximal extremity of the telescopic support is fitted a small stabilising shoulder plate (scapula pad). This support is shaped and padded to give maximum comfort, whilst providing stability at the shoulder. It is made of light alloy so that it may be moulded to the contours of the patient's shoulder shape. Attached to the tubular support, below the scapula pad, is a two-way hinge which connects the upper-arm steel to the support, thus allowing abduction of the flail shoulder to a maximum of 135 degrees and a maximum shoulder flexion of 82 degrees from a preflexion of 8 degrees relative to the line of the support tube.

The upper steels are in line with the medial aspect of the flail limb, with the arm-support troughs facing laterally. The adjustable ratchet mechanism at the elbow carries the forked section to which the upper-arm steel is connected and incorporates the lower-arm steel, which at its proximal extremity forms an integral

part of the ratchet lock. The lower steel has a preflexion of 10 degrees and a maximum flexion of 150 degrees from the preflexed position. Maximum flexion of the lower steel is used to unlock the mechanism, and adjustment to the locking positions is easily obtained by repositioning the adjustable stops. Both upper and lower steels can be cut back to length in stages of 12.7 mm (1/2 in.).

Attached to the distal portion of the lower steel is a detachable extension bar carrying a hand support and palmar bar. Combined arm troughs and attachment straps give full support and stability to the orthosis.

As an alternative to the waistband, it is possible to fit a shoulder girdle made from light alloy lined with Pe-Lite and covered with simulated leather (Figure 2. ). This unit is easily moulded by hand over the shoulder and around the chest wall. A light Velcro retaining strap stabilises the girdle. In the small size, this item is used in the rehabilitation of the child patient who, because of his size, has been unable to be fitted with this modular orthosis. A metal bracket is fixed to tl1e posterior aspect of the girdle in the area of the axilla. Onto this is fitted the remainder of the orthosis, which has had the scapula pad removed.

In order to use terminal devices, it is necessary to fit one of three sizes of plastic forearm troughs. These can be fitted with a minimum of cutting and moulding, and the metal receptor plate is then positioned and rivetted down. Into the receptor is fitted a standard keysnap fitting which will accommodate the terminal device.

The cable-control system, when fitted, allows the patient to operate terminal devices by using dynamic tension across the broad of the back where the greatest expansion occurs (Figure 3. ). To use the devices it is necessary to fit a positive-lock steel. The steel is easily interchangeable with the ratchet steel and is drilled and tapped to pitch. With locking positions of 31 and 1/2 degrees, 63 degrees, 94 and 1/2 degrees, 126 degrees, and 171 degrees from a preflexion of 9 degrees, maximum efficiency can be obtained by the patient.

Orthoses for flail arms tend to be rather bulky by comparison, and the problem of shoulder extension is ever present. The Mk 3 is a very neat support for a totally flail arm with a functional hand with normal sensation. Subluxation is prevented, and the geometry of the shoulder hinge and scapula pad prevents extension when the elbow is flexed and the hand is placed in the optimum position in front of the body. The orthosis can also be adapted for use with CO 2 gas.

Conclusions

For many years it was thought that a prosthesis was much more useful than a support splint, and the incidence of amputation and glenoid-humeral arthrodesis was quite high. However, most patients do not use their prosthesis, and almost all are reluctant to have an amputation. The orthosis offers the best of both worlds, a functional restoration and retention of the natural limb.

At a six-month follow-up of 71 patients fitted, 70 per cent were using the orthosis daily at work or for hobbies. The new shoulder girdle is making for a higher acceptance rate.

Acknowledgements

I wish to thank Dr. Redhead and Dr. Wynn-Parry, without whose help and encouragement the development of this system would not have progressed so quickly. My thanks also to my colleague, John Heritage 4 , who designed the shoulder girdle, and my employers, Hugh Steeper Limited, who afforded me the time and opportunity to prepare this article.

References:

 

    1. Senior Medical Officer, Limb Fitting Centre, Queen Mary's Hospital, Roehampton, London

 

    1. Director of Rehabilitation, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex

 

    1. Hugh Steeper Limited, 237/239 Roehampton Lane, London, SW 15 4LB

 

  1. Prosthetist-Orthotist, Hugh Steeper Limited.