A Welcome Alternative To Traditional Knee-Ankle-Foot Orthosis (KAFO)
28 Mar 2017
Providing effective and patient-acceptable orthotic intervention for individuals with knee instability resulting from lower-limb paresis or paralysis has been a long-standing challenge in our specialty.
Patients lacking full voluntary knee control secondary to polio, weak quads, spinal cord injury, multiple sclerosis, stroke and other neuromuscular and/or musculoskeletal disorders have traditionally been fitted with a knee-ankle-foot orthosis (KAFO) incorporating manual locking knee joints to provide stability during stance and thereby prevent knee collapse and resulting falls.
But knee motion is an essential ingredient of a normal, efficient gait.
Ambulating in a traditional locked-knee KAFO produces an awkward, highly inefficient walking pattern in which the wearer must circumduct and/or hike up the braced leg, or vault on the opposite leg, to provide foot clearance and advance the involved limb. This gait is awkward and fatiguing and thus unacceptable to many patients, who frequently choose to leave their brace in the closet as a result.
Another common outcome of abnormal compensating biomechanics associated with long-term use of a locked-knee KAFO is pain and loss of motion stemming from soft tissue and joint dysfunction, especially in the hips and lower back.
Stance Control Orthoses
Fortunately, a relatively new class of componentry called stance control orthoses (SCOs) now provides us with a viable alternative. The concept behind these devices – locking the knee during weight bearing for stability and allowing it to flex more-or-less normally during leg swing – wasn’t hard to figure out; but coming up with a reliable assembly acceptable to users proved elusive for decades. And while no one product among the various options currently available to us will apply generically, we now do have sufficient choices to address different patient needs, even as new and improved designs continue under active development.
Determining whether an SCO will be beneficial and if so which assembly will be most appropriate for a given individual is as much a function of correctly assessing the patient’s physical and cognitive capabilities as addressing the presenting diagnosis.
Only some individuals with post-polio symptoms, for example, have the facility and motivation to succeed with a stance control brace. The same is true with all other relevant diagnoses for this category.
The majority of currently available SCOs are mechanical designs, which employ some feature of the user’s gait such as ankle range of motion to lock the knee just before commencement of stance phase (heel strike) and unlock it at transition to leg swing. More recent microprocessor-controlled systems extend stance control benefits to individuals with minimal hip musculature that precludes using mechanical SCOs.
Though SCOs have not been around long enough for conclusive long-term outcomes studies, initial research involving some of the early designs suggests significant benefits can be achieved for appropriate patients notably substantially improved gait biomechanics coupled with less effort and energy expenditure and more normal motion of the affected limb as well as the rest of the body.
On the other hand, stance control KAFOs present certain drawbacks. The current generation of SCO joints tends to be somewhat bulky as compared to their standard cousins, and the newer microprocessor- controlled SCOs tend to be heavy by comparison; some are noisy as well. For the patient, the question becomes, Are these compensations worth the added performance the orthosis provides? In many cases, the answer is a definite Yes!
As with most new and technological advancements, stance control orthoses, particularly those with electronic function, are considerably more expensive than conventional KAFOs for this population. Moreover, obtaining reimbursement has been problematic; in fact, Medicare’s initial reluctance to provide funding for SCOs stymied product development for several years. Now, however, a reasonable code has been issued, and insurance funding for these orthoses can often be obtained with the necessary justification and documentation.
In evaluating patients for possible SCO application, we have learned that those who have worn a conventional KAFO typically have more difficulty adapting to and taking full advantage of the stance control features than individuals receiving their first orthosis.
From the increasing number of stance control products now commercially available in the U.S., knowledgeable orthotists can select the one offering the most appropriate mix of attributes for any given patient’s unique needs, body measurements, capabilities and activity expectations.
General contraindications to using a stance control KAFO include significant knee spasticity, substantial impairment of patient cognition and/or motivation, knee flexion contractures exceeding 10 degrees and uncertain prospects for patient follow-up and compliance.
To discuss stance control prospects for a specific patient or to learn more about this class of componentry, we invite you to call our office. We are located throughout southeast Texas in the cities of Beaumont, Nederland and Jasper. Your initial consultation is free.