Rehabilitation: Gait, Amputations, Prostheses, Orthoses, and Neurologic Injury

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Chapter 10

Rehabilitation

Gait, Amputations, Prostheses, Orthoses, and Neurologic Injury

Contents

section 1 Gait

WALKING

Definitions

1. Walking is the repetitive process of sequential lower limb motion to move the body from one location to another while maintaining upright stability.

2. Walking is a cyclic, energy-efficient activity: one foot must be in contact with the ground at all times (single-limb support), with a period when both limbs are in contact with the ground (double-limb support) (Figure 10-1).

3. The step is the distance between initial swing and initial contact of the same limb.

4. Stride is the period from initial contact to initial contact of the same limb (i.e., each stride comprises two steps) (Figure 10-2).

5. Velocity is a function of cadence (steps per unit of time) and stride length.

6. Running involves a period when neither limb is in contact with the ground.

Phases: Prerequisites for normal gait include stance-phase stability, swing-phase ground clearance, the correct position of the foot before initial contact, and energy-efficient step length and speed.

1. The stance phase occupies 60% of the cycle.

2. The swing phase is 40% of the cycle.

3. Important characteristics of gait cycle:

II GAIT DYNAMICS

III DETERMINANTS OF GAIT (MOTION PATTERNS)

    In mechanical terms, there are six independent degrees of freedom (Figure 10-4):

Pelvic rotation: The pelvis rotates horizontally about a vertical axis, alternately to the left and right of the line of progression, lessening the center-of-mass deviation in the horizontal plane and reducing the impact at initial floor contact.

Pelvic list: The non–weight-bearing, contralateral side drops 5 degrees, reducing superior deviation.

Knee flexion at loading: The stance-phase limb is flexed 15 degrees to dampen the impact of initial loading.

Foot and ankle motion: Through the subtalar joint, damping of the loading response occurs, leading to stability during midstance and efficiency of propulsion at push-off.

Knee motion: The knee works together with the foot and ankle to decrease necessary limb motion. The knee flexes at initial contact and extends at midstance.

Lateral pelvic displacement: This relates to the transfer of body weight onto the limb. The length of motion is 5 cm over the weight-bearing limb, narrowing the base of support and increasing stance-phase stability.

IV MUSCLE ACTION

Agonist and antagonist muscle groups work in concert during the gait cycle to effectively advance the limb through space.

The hip flexors advance the limb forward during the swing phase and are opposed during terminal swing, before initial contact by the decelerating action of the hip extensors.

Most muscle activity is eccentric, which is muscle lengthening while it contracts, and allows an antagonist muscle to dampen the activity of an agonist and act as a “shock absorber” (Figure 10-5).

Isocentric contraction is muscle length’s remaining constant during contraction (Table 10-1).

Some muscle activity can be concentric, in which the muscle shortens to move a joint through space.

PATHOLOGIC GAIT

    Abnormal gait patterns are caused by the following factors:

Muscle weakness or paralysis: decreases the ability to normally move a joint through space. A walking pattern develops on the basis of the specific muscle or muscle group involved and the ability of the individual to acquire a substitution pattern to replace that muscle’s action (Table 10-2).

Neurologic conditions: may alter gait by producing muscle weakness, loss of balance, reduced coordination between agonist and antagonist muscle groups (i.e., spasticity), and joint contracture.

Pain in a limb: creates an antalgic gait pattern, in which the individual shortens the stance phase to lessen the time that the painful limb is loaded. The contralateral swing phase is more rapid.

Joint abnormalities: alter gait by changing the range of motion of that joint or producing pain

Hemiplegia: characterized by prolongation of stance and double-limb support

Crutches and canes: devices that ameliorate instability and pain, respectively

Arthritis: Forces across the knee may be four to seven times those of body weight; 70% of the load across the knee occurs through the medial compartment.

Water walking: There is a significant decrease in joint and total joint contact forces as a result of the effect of buoyancy.

section 2 Amputations

INTRODUCTION

II METABOLIC COST OF AMPUTEE GAIT

III LOAD TRANSFER

The soft tissue envelope acts as an interface between the bone of the residual limb and the prosthetic socket.

Load transfer (i.e., weight bearing) occurs either directly or indirectly.

1. Direct load transfer (i.e., terminal weight bearing) occurs in knee or ankle disarticulation (Syme amputation). For direct load transfer, intimacy of the prosthetic socket is necessary only for suspension.

2. When the amputation is performed through a long bone (i.e., transfemoral or transtibial), the end of the stump does not take all the weight, and the load is transferred indirectly by the total contact method.

IV AMPUTATION WOUND HEALING

    The healing of amputation wounds depends on several factors, which include vascular supply, nutrition, and an adequate immune status. Transcutaneous partial pressure of oxygen is the factor that is most predictive of whether wound healing will be successful.

Nutrition and immune status:

Vascular supply: Oxygenated blood is a prerequisite for wound healing, and a hemoglobin concentration of more than 10 g/dL is necessary. Amputation wounds generally heal by collateral flow; thus, arteriography is rarely useful for predicting the success of wound healing.

1. Standard Doppler ultrasonography helps measure arterial pressure and has been used as the measure of vascular inflow to predict the success of wound healing in the ischemic limb.

image An absolute Doppler pressure of 70 mm Hg was originally described as the minimum inflow pressure to support wound healing.

image The ischemic index is the ratio of the Doppler pressure at the level being tested to the brachial systolic pressure. It is generally accepted that patients require an ischemic index of 0.5 or greater at the surgical level to support wound healing. The ischemic index at the ankle (i.e., the ankle-brachial index) is the most accepted method for assessing adequate inflow to the ischemic limb.

image In the normal limb, the area under the Doppler waveform tracing is a measure of flow. In at least 15% of patients with diabetes and peripheral vascular disease, those values are falsely elevated and not predictive because of the incompressibility and loss of compliance of calcified peripheral arteries. The ischemic index for toe pressure is more accurate in such patients and, if greater than 0.45, is usually predictive of adequate blood flow.

2. Transcutaneous partial pressure of oxygen is the current “gold standard” for measurement of vascular inflow. It reflects the oxygen-delivering capacity of the vascular system to the level of contemplated surgery.

PEDIATRIC AMPUTATION

Pediatric amputations are usually undertaken because of congenital limb deficiencies, trauma, or tumors.

Congenital amputations are the result of failure of formation.

The current classification system is based on the original work of the 1975 Conference of the International Society for Prosthetics and Orthotics (ISPO) and the subsequent standard developed by the International Organization for Standardization (ISO).

Deficiencies are either longitudinal or transverse, with the potential for intercalary deficits.

Amputation is rarely indicated in congenital upper limb deficiency; even rudimentary appendages can be functionally useful. In the lower limb, amputation of an unstable segment may allow direct load transfer and enhanced walking (e.g., Syme amputation for fibular hemimelia).

In a growing child, disarticulations should be performed only when it is possible to maintain maximum residual limb length and prevent terminal bony overgrowth.

VI AMPUTATION AFTER TRAUMA

    The grading scales for evaluating mangled extremities are not absolute predictors but provide reasonable guidelines for determining whether salvage is appropriate.

Indications

1. The absolute indication for amputation after trauma is an ischemic limb with a vascular injury that cannot be repaired.

2. The guidelines for immediate or early amputation of mangled upper limbs differ from those for mangled lower limbs.

3. Early amputation in appropriate scenarios may prevent emotional, marital, financial, and addiction problems.

4. Most grades IIIB and IIIC tibia fractures occur in young men who are laborers and may be more likely to return to gainful employment after amputation and prosthetic fitting.

5. Sensation is not as crucial in the lower limb as in the upper limb, and current prostheses more closely approximate normal function.

6. Disadvantages of limb salvage:

Contraindications

VII RISK FACTORS

Cognitive deficits

Diabetes

Peripheral vascular disease

1. Most of the other patients who undergo amputation are malnourished patients with peripheral vascular disease of sufficient magnitude to necessitate amputation, and their coronary and cerebral arteries are diseased.

2. Appropriate consultation with physical therapy, social work, and psychology departments is important to determine rehabilitation potential.

3. Medical consultation helps determine cardiopulmonary reserve. The vascular surgeon should determine whether vascular reconstruction is feasible or appropriate.

4. The biologic amputation level is the most distal functional amputation level with a high probability of supporting wound healing.

5. Morbidity and mortality rates have remained unchanged for several decades. Thirty percent of patients with peripheral vascular disease die in the first 3 months after amputation, and nearly 50% die within the first year. The overall rate of prosthetic use is 43%.

VIII MUSCULOSKELETAL TUMORS

Goal of surgery: to remove the tumor with adequate surgical margins.

Amputation versus limb salvage:

IX TECHNICAL CONSIDERATIONS

Skin flaps should be of full thickness, and dissection between tissue planes should be avoided.

Periosteal stripping should be sufficient to allow for bone transection; this minimizes regenerative bone overgrowth.

Wounds should not be sutured under tension. Muscles are best secured directly to bone at resting tension (myodesis) rather than to antagonist muscle (myoplasty).

Stable residual limb muscle mass can improve function by reducing atrophy and providing a stable soft tissue envelope over the end of the bone.

All transected nerves form neuromata. The nerve end should come to lie deep in a soft tissue envelope, away from potential pressure areas. Crushing the nerve may contribute to postoperative phantom or limb pain.

Rigid dressings (postoperative) help reduce swelling, decrease pain, and protect the stump from trauma.

Early prosthetic fitting is done within 5 to 21 days after surgery in selected patients.

COMPLICATIONS

Pain

Edema

Joint contractures

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