BOSS Gait Training:

B.O.S.S. is the author's acronym for "Bend-Out-Short-Step," a simple mnemonic to facilitate modification of the helicoped gait that is typically developed status post traumatic brain injury (TBI) and other cardiovascular accident (CVA).

Developed several years ago by this writer in response to presentations that routinely evidence serious deficits in gait training, the 'BOSS' approach dramatically reduces dependence on the use of orthotic devices, and in some cases eliminates their need altogether. In almost every case we have seen, the patient's brace is not correctly fitted: the most common problem is compression of the peroneal unit, thereby weakening the stabilizing muscle and creating greater dependence on the brace. In addition, over time, the non-swiveling models that are commonly prescribed promote a shortening of the Achilles tendon, further causing the foot to point downwards and increasing the risk of tripping and suffering falling injury.

IMPORTANT! It should be understood that no therapeutic intervention for spastic hemiplegia can be expected to provide abiding results if the patient's cognitive processes are not recruited in the care. Hence, psychophysiological response therapy with non-invasive electromyography (sEMG) is the treatment of choice; since both learning and practice are involved. No hemiplegic patient has a "bad" leg: the problem is generally in the myotatic unit with dysfunctional muscle proprioception, governed by the motor cortex. Yes, it's all in the head! 

An illustrated overview of the BOSS gait is provided below.

PATHOPHYSIOLOGY

Before illustrating the BOSS gait, a summary of the helicoped gait is shown.

The untreated hemiplegic employs a helicoped gait, commencing with a contralateral leaning of the body to allow room for the affected lower extremity to clear the ground. The resulting pressure of the hand on the cane can cause painful cysts to develop in the metacarpal joints, due to repeated strain, and Heberden's arthropathy is likely to follow later in life. The flexor muscles, those that reduce the angle at a joint, tend to be in spasm; and tonic spasticity amounts loss of strength. As a result, the propulsion phase (plantar flexion) in the gait is markedly truncated. The extensor muscles tend to be paralytic, and the debilitated tibialis anterior, which is the prime mover for dorsiflexion, causes the foot to point downwards. Risk of falling injury increases proportionally.  

Typically, the fully extended limb swings in an arc, the foot pointing downward and inward, resulting in foot inversion when the step is completed (see arrow in figure 1). When body weight is transferred to the so-called "bad" leg, the ankle places maximum strain on the brace. The ensuing and repeated compression on the peroneal nerve renders the stabilizing muscle inefficient. The wide arc places the foot far ahead of the other, and the individual is then compelled to accelerate and lose control of balance. Falling is such instance is inevitable. 

The arrow in figure 2 below shows the path of the widely swinging limb. Notice that body weight is placed on the so-called "good leg," in order for the extended "bad leg" to clear the ground. As a result, body tilt forces the individual to further depend on use of a cane, which grip if not fashioned to the contour of the hand over time can cause a repetitive strain injury (RSI). Use of a cane allows the patient to ambulate with some confidence, but it also interferes with important brain reorganization for the development of balance.

Toe points inward, setting up foot inversion. Notice the large step taken, which promotes acceleration and loss of balance.

Before trunk weight is placed on the lower extremity, the leg is commonly bent to facilitate clearance from the ground. The consequence of shifting weight to a bent limb can cause the knee to violently hyperextend (snap back), placing a placing a tremendous strain on the ligaments (see arrow in figure 4). Such injury usually requires many weeks of rest and use of antiinflammatory medication. The hemiplegic patient with limited sensation in the limb will not benefit from discomfort and exacerbate such an injury through continued use and strain of the joint. See "Effective Support" section below for a description of an exercise that can help the patient develop prophylaxis against such future injury.

With the forward motion and weight place on an inverted foot--especially if acceleration has occurred--the individual begins to fall. The cane in the contralateral hand provides no support. Ipsilaterally, the monoplegic upper extremity is unable to buffer the fall. With comorbid short-term memory deficit, repeated head injuries often go unreported. But the TBI symptoms of weakened grip strength, word-finding-difficulty, STM deficit, low frustration tolerance (compromised IQ), change in personality, minimization, and reactive or blunted affect may become more noticeable.

WARNING!!! Walking with a partially flexed limb, such as in the manner that Groucho Marx would often display in his movies, may cause the leg to try and violently hyperextend when body weight is placed on the limb. This type of gait may also be antalgic, the discomfort unreported. In this instance, the heel strike is absent; and the foot is placed down flat on the floor. The weight of the trunk forces the leg to suddenly snap backwards and cause ligamental and tendon injury, which may require use of a full-length leg orthosis and months of rehabilitation. In some cases, if the cognitive deficits are severe, the injury can be permanent, perpetuated by unconscious dragging of the medial aspect of the foot during the post-propulsion phase of the gait. Genetic loading for enthesopathy will compound the problem. Since many TBI patients with hemiplegia also suffer short-term-memory deficit (STM), how or when the injury is sustained may not be recalled when a vague complaint of discomfort is reported. The picture above shows the step that predisposes the individual to the knee injury: the red arrow points in the direction the knee can painfully snap back. Developing the habit of executing a heel strike, with leg fully extended, will prevent the injury.

BOSS Gait (overview)

The BOSS gait commences after the trainee places the cane (if used) approximately one-half step forward, visualizing the trunk as on two pedestals. A good primer for functional gait restoration is blind practice of balancing on two bathroom scales. When able to estimate the distribution of body weight within 5 lbs, the trainee is better prepared for gait training. 

BEND. The knee bends, allowing the foot to clear the ground without need to lean to the opposite side (see figure 2). the cane is used solely for reference, much like when skiing in snow.

OUT. The toe is pointed outward, but not to the extent of appearing to walk like Charlie Chaplan. About 17 degrees is ideal. Excessive pointing out of the foot can cause ligamental strain in the knee joint. Periodic monitoring of the adopted angle, along with proprioceptive awareness training should be an integral part of the treatment plan. If the trainee is unable to point the toes outward, neuromuscular training of the gluteals--with imperative cognitive involvement--will be required before proceeding; since paresis in the buttock muscles impedes necessary lateral rotation of the limb.

SHORT STEP. Arrow in figure 8 points to the protective heel strike, which is no more than approximately 8 inches in front of the other foot to prevent acceleration. The left hip and buttock are raised slightly and drawn back to shorten the stride. A heel strike locks the limb in a fully extended position, making hyper-extension impossible... the knee then cannot violently snap backwards and cause painful knee joint damage. Instead, body weight is smoothly rolled over onto the leg as the toes come down to touch the floor.

With the foot pointed outward, inversion is virtually impossible; and the subject is in perfect position for the next step. Notice that the distance of the short step is approximately equal to the length of the individual's foot. When taking a step forward with the "good leg," caution should be taken to avoid the medial aspect of the foot from dragging on the ground, especially when sneakers are worn on carpet where friction is greatest. When the foot at the medial and proximal phalanx joint surface is dragged on the ground--however briefly--the knee joint is subject to repetitive strain injury (RSI), twisted and strained by the drag.

OBSTACLES

1. By far the greatest obstacle a hemiplegic faces in the rehabilitation effort is overcoming deficits of motivation for regaining function beyond that which he or she has acquired in the first year, following the cerebral insult. Emotionally immature victims, those with compromised ability to delay gratification, fare the most poorly in treatment.

2. With the exception of one instance, this writer has never seen a leg brace that did not cause some deterioration of the affected limb. Almost the rule is sustained compression of the peroneal muscle and nerve, vital to stable gait. Without anatomical cushioning, the edge of the upper strap leaves a permanent and disfiguring depression proximal to the superior gaster section of the peroneus longus. How professionals routinely overlook this fact is puzzling. The higher grade visco elastic foam, which responds to skin temperature and molds itself to the contour of the limb, distributes strap pressure over a larger area and thereby reduces iatrogenic palsy and atrophy of the lateral muscle group. Outdated and non-functional (non-swiveling), ankle orthoses should never be prescribed as they invariably cause continued shortening of the Achilles tendon by restricting posterior leg muscle extension. As a result, the individual experiences increased restriction of mobility; increased dependence on the orthosis; decreased balance; and increased difficulty in placing the foot into a shoe, the heel raised and foot pointed down and inward.      

3. Paralysis in the gluteal region impedes lateral rotation of the affected limb, thereby frustrating effort to point the foot outward. The "O" in B.O.S.S. becomes impossible. In such cases, therapeutic intervention of facilitating development of proprioceptive awareness and muscle strengthening of the gluteals must precede any gait training to prevent discouragement. Biofeedback training techniques with surface electromyography (sEMG) have proven the most effective in strengthening the motor unit and correcting the dysfunction. The latter approach also has the invaluable advantage of determining if muscular contraction causes spasticity, so that exercises for strengthening the limb may be stopped before causing harm.  

4. Well-intended but often less-than-productive family support is common: fear of the victim falling and suffering another head injury often predisposes caregivers to imposing restrictions that hinder the recovery effort. Overly protective measures usually lead to the victim needlessly becoming wheel chair bound.

EFFECTIVE SUPPORT

The caregiver's role should be gradually phased out after the patient is released from hospital to avoid the development of learned helplessness and reward of any secondary gain. The patient will benefit from coaching as independence is fostered. Simply put, the main difference between caregiving and coaching is the difference between telling the patient WHAT to do and HOW how to do it.

But even the most kind natured subject can become irritable and defensive, and a coach's patience is often tested. The teaching of the HOW is therefore safer to deliver by the asking of questions that lead to new learning. Of course, the coach will need a formidable arsenal of clinical knowledge. And, if the patient's therapist is seasoned (not a cook-book type), participating in the patient's therapy will provide a home coach with a wealth of information.    

The emphasis is on working with--and not for--the subject. The most skilled coaches guide you indirectly. They are motivating catalysts and will have you teach them how to perform what you think you have learned on your own. Hence their only reward is quietly watching the subject succeed.

Knowledge learned through insight is knowledge permanently owned and so much more likely to be useful. Indeed, a guided question can penetrate resistance and psychologically empower the powerless when in denial. 

Since most TBIs involve STM deficits, the home treatment assignment of kicking a tennis ball to and fro on grass with a partner will ensure compliance. In order to make contact with the heel of the affected limb, the leg must fully extend (with dorsiflexion of the foot), which eliminates the possibility of injurious hyperextension. Specifically, the exercise facilitates a particular "wiring" of the brain, whereby the prohylactic heel strike during the weight bearing phase of gait becomes habitual.    

TREATMENT EXERCISE #1

As mentioned earlier, no amount of physical therapy will provide lasting benefit if the patient's cognitive processes are not involved. Both the patient and support team need to maintain awareness of the fact that there is no such thing as a "bad leg." The problem of paresis is in the brain, not the limb. The following exercise was developed by this writer to reduce the latency of recall of treatment information and promote a reflex response or habituation to a more functional gait. The exercise begins with single stage commands and progresses to the multiple stage. As the individual gains the ability to respond spontaneously, the ability to perform the action stated will increase. 

Warm up. The patient is challenged to respond as quickly as possible with antonyms to a series of terms: Up (down), left (right), forwards (backwards), etc. Retrieval of stored information is practically useless if response latency is greater than the amount of time required to execute the action.  

SINGLE STAGE (support): Are you ready for our exercise? Remember, if I say bend," you say "out. If I say "heel," you say "strike." If I say "short," you say "step." OK? (support mixes up the sequential order of the commands only after the patient responds correctly several times). 

MULTIPLE STAGE (support): You're doing so well that I think we can try something more advanced. If I say "bend," you say "out and short step." If I say "heel,"you say "strike and shift weight." Ready?  

TREATMENT EXERCISE #2

Rehearsal (visualization). The support person states in sequence the commands for the BOSS gait in detail, and the patient pictures in his or her mind the action stated: Bend (Pt visualizes a leg bending and lifting off the floor)...out (visualizes toes pointing out)...short (pictures a short stride)...heal strike (pictures straight leg with heel striking the ground)...shift (pictures body weight shifted to the fully extended limb). Start out slowly and increase the tempo after the patient is able to more readily visualize the image. There should be no pause between the mental images. Reward effort with recognition of success, which may be monitored by asking the patient to describe the action visualized: Whose leg? What did the shoe look like, etc. The more detail verbalized, the better the progress. 

TREATMENT EXERCISE #3

The following is more of a memory exercise but it can facilitate reduction in response latency when executive memory is challenged in gait training. The more participants in the "game" the better. A minimum of two people are required for the exercise.

Sitting in a circle, one person starts counting from "one." Any number evenly divisible by three is replaced by the word "fizz." Any number evenly divisible by two is replaced by the word "buzz." Numbers such as six and 12 are replaced by "fizz-buzz." Either tally points or, if the number of participants is four or more, anyone who responds incorrectly drops out until the last person is declared the winner. Self correction of a response is deemed an error: for example, "Fi..er buzz" is counted as incorrect. Responses may be limited by time, such as anyone taking longer than three seconds is out. The correct order would be "one...buzz...fizz... buzz...five...fizz-buzz...seven...etc. Note that players must mentally keep track of the count when somebody else is taking a turn.

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Information about professional seminars for the delivery of BOSS gait training is available upon request. Therapists interested in acquiring for their armamentarium the tools necessary for delivering the full course of BOSS gait training may contact me at the address below.

The Neurobehavioral Medicine Center                                                       4821 U.S. Highway 19 N                                                                        Suite #1                                                                                              New Port Richey, FL 34652                                                                    U.S.A.                                                                                                 Tel: (727) 849-2005                                                                               Fax: (727) 849-2087

Otsenre E. Matos, M.D., Medical Director (Neuropsychiatry)                            Gerard J. Taylor, Ph.D., (Biobehavioral Medicine)

NOTE: We encourage use of the information herein to help any TBI or stroke patient regain gait stability when afflicted with monoplegia of the lower extremity, and respectfully ask that credit be given to the author, Gerard J. Taylor, Ph.D., for development of the BOSS gait.

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This page last updated September 27, 2008