Pertinent Pearls On Custom Orthoses And Modifications

Author(s): 
Clinical Editor: Nicholas Romansky, DPM

These expert panelists explore the efficacy of orthoses for hallux limitus, the impact of orthotic devices on the kinetic chain and key considerations with topcovers.

Q:

How do you use orthotics for hallux limitus?

A:

David Levine, DPM, CPed, notes hallux limitus can be a challenging problem to treat conservatively and surgically. He says it is helpful to distribute the pressure more evenly across the forefoot.

   In some instances of hallux limitus, it is also key to reduce the forces going through the first ray and Dr. Levine says one can accomplish this in several ways depending upon the foot type. He notes some patients respond to a cutout for the first ray, which can allow relative plantarflexion, and some patients respond to a Morton’s extension. R. Paul Jordan, DPM, also notes the efficacy of a cutout under the first metatarsal head. He says this orthosis shell modification offers an adequate contour for the first metatarsal to plantarflex, which permits relative, passive hallux dorsiflexion at the first metatarsophalangeal joint (MPJ) in the terminal stance phase of gait.

   Furthermore, Dr. Levine notes some patients require limited pronation in the terminal portion of midstance in order to prevent dorsiflexion and jamming of the first ray. Likewise, for Kevin Kirby, DPM, the goal of orthosis therapy is to reduce the dorsiflexion of the first ray in patients with functional or structural hallux limitus, who have a restriction in dorsiflexion of the hallux but no pain at the end of hallux dorsiflexion range of motion. Reducing dorsiflexion of the first ray lessens the tensile force within the medial band of the plantar fascia during late midstance and propulsion, according to Dr. Kirby. If one can reduce the tension within the medial band of the plantar fascia with a foot orthosis, he says this will decrease first MPJ compression forces.

   Dr. Kirby also says that by designing the orthosis to allow more normal hallux dorsiflexion during propulsion, this will allow the re-establishment of more normal gait function in the patient. To accomplish this, he suggests designing the orthosis to reduce pronation motion of the foot by using a medial heel skive and tightly fitting medial longitudinal arch. By using a reverse Morton’s extension, Dr. Kirby says one can design the device to reduce the ground reaction force plantar to the first metatarsal head.

   However, if the patient has a structural hallux limitus or hallux rigidus, and the patient reports pain within the joint at the end of hallux dorsiflexion range of motion during the non-weightbearing examination, Dr. Kirby advocates including a Morton’s extension instead. As he explains, the Morton’s extension, by dorsiflexing the first ray, will reduce hallux dorsiflexion, eliminate the painful end range of dorsiflexion motion and make propulsion less painful during walking gait.

   Although he does not see patients with hallux limitus in his pediatric practice, Dr. Jordan treats a significant number of children with a functional hallux limitus. He notes the symptoms are rarely localized in the great toe or even the foot when pediatric functional hallux limitus is a component of the child’s pedal pathomechanics. Most often, the functional limitation affects proximal structures in a compensatory reaction to the limited motion at the first MPJ, which he notes poses an obstacle to an efficient or fluid terminal stance phase of gait.

   Since there are many biomechanical strategies that one can use, Dr. Levine notes the most important factors are the patient history and the biomechanical exam.

   “Often other variables will present and if they are addressed properly, the chance of favorable results with conservative care will increase,” notes Dr. Levine.

Q:

Do you have any pearls on the effective use of custom orthotics on the kinetic chain other than feet?

A:

Since the foot is the location of the compensation for what happens more proximally within the kinetic chain, Dr. Levine stresses the importance of assessing the legs, knees, thigh segment, hips and low back both from a static as well as a dynamic perspective.

   Dr. Kirby agrees about the importance of addressing biomechanics.

   “The podiatrist who understands how foot function affects the biomechanics of the lower extremity and how lower extremity function affects the biomechanics of the foot, and can implement this knowledge into effective custom foot orthosis prescriptions for their patients will always be a very valuable member of the medical community. He or she will be able to offer conservative treatment options to patients who are reluctant to take the time away from work, experience the postoperative disability and encounter the risks of surgical treatment options,” asserts Dr. Kirby.

   Dr. Jordan emphasizes the importance of ascertaining a full history and physical to determine if the pathomechanics of the feet are contributing to the proximal concerns or complaints. He says one must determine if the child’s feet are the driving force affecting the proximal pathomechanics or if the pedal structures are expressing a proximal musculoskeletal disorder.

   “Conditions labeled as growing pains, patellofemoral pain syndrome, trochanteric bursitis (from extremes of internal femoral rotation), peroneal muscle spasm (such as tarsal coalitions with equinus) or Osgood-Schlatter disease are but a sampling of the many complaints that are effectively and quickly addressed through custom fabricated orthoses,” says Dr. Jordan.

   Dr. Jordan says the key, after knowing the pain is not due to systemic medical conditions, is distinguishing between the pathomechanical “findings” and the “problem(s).” After identifying the problem, he notes he and his colleagues have been 99 percent successful in resolving pain associated with recalcitrant “growing pains” and similar overuse syndromes that manifest as pain above the foot.

   Dr. Kirby notes the potential of using custom orthoses to reduce the pathological internal loading forces that cause a number of injuries. Such injuries include: leg injuries such as medial tibial stress syndrome, peroneal muscle fatigue, posterior tibial and peroneal tendinitis/tendinosis; knee injuries such as patellofemoral pain syndrome, iliotibial band syndrome, medial and/or lateral compartment osteoarthritis and pes anserinus bursitis; and many mechanically-related hip and low back complaints.

   “I often tell patients that the further you go away from the feet, the harder it is to predict how successful the orthotic devices will be in alleviating their complaints,” says Dr. Levine. “We have all had patients for whom orthotic devices have aided in resolving back pain so we know that there is an effect throughout the kinetic chain.”

Q:

How do you determine which topcover to use?

A:

In a pediatric practice, Dr. Jordan notes that topcovers are not necessary and all too often take up needed space within the child’s footwear. He argues that cellular cushioning topcovers for added shock absorption, comfort and protection are unwarranted, even for the child with an insensate spina bifida foot or the high arched foot type of Charcot foot.

   More important are the shock absorbing materials of the footwear that come into contact with the ground well before the foot structures do, according to Dr. Jordan. He notes that often the child’s plantar soft tissues, which are contained within the orthosis shell, offer considerably greater impact shock absorption than a topcover.

   Dr. Levine says one can use a variety of topcovers ranging from thin leather to thick Spenco, emphasizing that the key factor is how the orthotic will fit the shoe. In many instances, he says it is easier to remove the insole of the shoe and replace it with a full-length device that will occupy approximately the same volume.

   The process is a bit more complicated when the patient wears several different styles of shoes. For these patients, Dr. Levine says it is sometimes easier to cover only the orthotic device and not have an extension. As he points out, one can then accommodate each pair or style of shoe with various insoles in order to accept the orthotic devices.

   Dr. Jordan is a Past Associate Professor at the New York College of Podiatric Medicine. He is a Diplomate of the American Academy of Cerebral Palsy and Developmental Medicine, and a Diplomate of the American Board of Podiatric Orthopedics and Primary Podiatric Medicine. Dr. Jordan is in private podopediatric practice in Smithtown, N.Y.

   Dr. Kirby is an Adjunct Associate Professor within the Department of Applied Biomechanics at the California School of Podiatric Medicine at Samuel Merritt University in Oakland, Calif. He is in private practice in Sacramento, Calif.

   Dr. Levine is a Fellow of the American Academy of Podiatric Sports Medicine. He is in private practice and is the director and owner of the Frederick, Md.-based Walkright and Physician’s Footwear, a fully accredited pedorthic facility.   

   Dr. Romansky is a Fellow of the American College of Foot and Ankle Surgeons. He is in private practice at Healthmark Foot and Ankle Associates in Media and Phoenixville, Pa.

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