In September, we introduced you to two patients who have suffered high-level, upper-extremity amputations; Ted, who had a transhumeral amputation, and Marvin, who suffered a shoulder disarticulation. 

To prepare for these challenging fittings, Scott Schall attended the latest MyoBock course in Minneapolis and then Scott, John Brandt, and Ted attended Otto Bock's "Dynamic Arm" course 3 weeks later. 

In this picture, Scott has 2 electrodes held in place on his forearm with the blue band. 

One electrode is positioned on his extensors and the other

is positioned on his flexors. 

Scott's muscle activity is recognized by the electrodes which then operate wrist rotation and/or the SensorHand SPEED.

Twice as Fast and Even More Responsive

With a dizzying 300mm per second opening/closing speed and enhanced EMG signal processing, the new SensorHand™ SPEED has unmatched speed and responsiveness. In addition, the unique AutoGrasp feature keeps held objects from slipping by monitoring and changing grip force as needed.

There are many ways to program the wrist and hand.  In this video, Scott has selected a program in which slow wrist extension will open the hand while quick wrist extension will supinate the wrist.  And conversely, slow wrist flexion will close the hand while quick wrist flexion will pronate the wrist.  In this program, opening and closing the hand is non-proportional (constant speed) while supinating and pronating the wrist is proportional to the strength of the muscle contraction.

Dynamic Arm

Don't miss the next issue... it will feature both Ted and Marvin with their finished upper extremity prostheses with the Dynamic Arm!

• 50,000 new amputations every year in USA based on information from National Center for Health Statistics
• Ratio of upper limb to lower limb amputation is 1:4 (4)
• Most common is partial hand amputation with loss of 1 or more fingers, 61,000
• Next common is loss of one arm, 25,000
• Existence of 350,000 persons with amputations in USA, 30% have upper limb loss.  Of this, wrist and hand amputations are estimated to make up 10% of upper limb population
• Transradial amputations make up 60% of total wrist and hand amputations which means 70% of all persons with upper limb amputations have amputations distal to the elbow
• In US 41,000 persons are registered who had an amputation of hand or complete arm
• 60% of arm amputations are between ages 21 and 64 years and 10% are under 21 years of age

Causes leading to amputation

• Reasons for amputation include cardiovascular disease, traumatic accidents, infection, tumors, nerve injury, and congenital anomalies
• Most frequent causes of upper limb amputation are trauma and cancer, followed by vascular disease
• Right arm more frequently involved in work related injuries
• Congenital upper limb deficiency has an incidence of approximately 4.1 per 10000 live births (4)

Causes of Upper Extremity Amputation (in percent)

Congenital . . 8.9%

Tumor. . . .. . 8.2%

Disease . .  . 5.8%

Trauma . .. .. 77%

Source

Reminder:  The 8^th course in the "Prosthetics for Therapists" series will cover Upper Extremity Prosthetics.