Lower Extremity Mobility Aid: The LEMA Strap
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I have been doing a series of training courses for orthotists interested in Horton's Stance Control Orthotic Knee Joint. One of the benefits of traveling around the country and meeting with so many colleagues is the opportunity to learn little tips and tricks from other clinicians. I am always delighted to learn from others' success, and often amazed at how effective seemingly simple solutions can be.
After the Dallas SCOKJ Qualifying Course concluded, I had the pleasure of chatting with Raymond Joyce CO and his wife, and learned that Ray the inventor of the LEMA strap. I have recommended this device from time to time as therapy equipment, to help the PT train patients with hip flexion weakness. Ray tell me the he has patients who have elected to wear the LEMA strap long term, if their paresis is permanent, in which case he modifies the "shoe stirrup" so the straps attach to chafes on the patient's shoe.
This product is a great example of how a good orthotist identifies a clinical problem and comes up with a practical clinical solution. Ray designed the LEMA strap to provide an external hip flexion moment, and suggested it may be useful for some SCOKJ candidates with weak or absent hip flexors. Consumers and health care professionals can learn more about this slick and simple orthosis at www.lemastrap.com and order one directly from Ray.
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We spend a fair bit of time reviewing the kinematics and kinetics of normal and pathologic gait during the SCOKJ Qualification Course, and one of the key points is how hip flexors disrupt swing phase kinematics, resulting in minimal toe clearance. Now that the SCOKJ is available, and for the first time we have an alternative to locking the patient's knee in full extension, hip control becomes an increasingly important consideration.
The power source for the LEMA strap is a 2-inch piece elastic billet attached to a fabric waist belt. The balance of the device is made from non-elastic strapping and Velcro. The patient adjusts the billet tension to create the desired hip flexion moment.
The Velcro strap behind the knee can be used to fine-tune the knee extension effect. The looser the popliteal strap, and the more anterior the shin straps are positioned, and the greater the knee extension moment created during swing phase. In like fashion, the more anterior the leather "shoe stirrup" is placed, the greater the ankle dorsiflexion moment created. It is very simple to find, through iterative trials, the optimal position for each individual that provides the best biomechanical forces to supplement their voluntary muscle control.
Ray also tells me that he has patients who have learned to rotate the belt to create an internal or external rotation moment at the hip, to compensate for muscular imbalances. This can be very useful in helping to insure that knee flexion is congruent with the line of progression.
To apply these concepts to a KAFO, the fork strap can be attached to the thigh or shin section of the orthosis, depending on the biomechanical functions desired. Now that Horton's SCOKJ has ushered in a new era in orthotic management where we can offer much more normal swing phase motion to many patients, hip control strategies such as these will become increasingly important.
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