The foot/ankle is our body’s interface with the ground! This makes it the critical base for skills like standing, weight shifting, cruising, and walking. There are 33 joints in the human foot! Maintaining or improving the alignment of these joints promotes optimal load bearing, improves stability, and optimizes muscle pull and function all of which increase the independence, efficiency, and safety with which we move through our environment.
Because of its importance as our body’s foundation, many interventions from orthopedists, orthotists, and physical therapists are aimed at improving foot/ankle alignment, range of motion, muscle strength, motor control, and balance in order to maximize gross motor function.
Serial casting is a non-invasive intervention that can be incorporated into your child’s physical therapy to address all of the above mentioned goals.
Serial casting is an intervention to gradually and progressively improve ankle range of motion, specifically ankle dorsiflexion (bringing the toes up). Research indicates that traditional short duration manual stretches do not produce long lasting changes in muscle length (Ryan ED, Beck TW, Herde TJ 2008). One study reports the soleus (calf) muscle must be stretched for at least 6 hours a day for effectiveness (Tardieu 1987). Serial casting is a way to improve range of motion by progressively casting to maintain the foot and ankle in a more optimal physiologic alignment.
Casts are set in a comfortable position with a very low load of resistance. Your child should not experience the feeling of “stretch”, so apart from the added weight of the casts it should be a very comfortable intervention. Serial casting can help your child reach goals of improving range of motion, standing balance, and gait mechanics while potentially delaying or preventing need for other more invasive medical or surgical orthopedic interventions.
In addition to progressively increasing ankle range of motion, serial casting helps the child to weight bear on the appropriate surfaces of their feet (i.e. shift their weight back onto the heels). This helps develop improved balance skills and lateral weight shifting necessary for increased safety and independence with skills like standing, cruising, and walking.
Unlike a traditional cast (say for a broken bone) where the goal is immobilization, serial casting is an active process. Children are encouraged to participate in a standing program, walk, and play in their casts in order to learn to load weight onto their heels and to improve their balance. It is important that children participate in physical therapy and a program of home exercises in conjunction with the serial casts to maximize effectiveness.
Serial casts are removed and replaced on a weekly basis. The casts we fabricate at NAPA can be easily removed by parents at home to allow 1-2 days out of the casts before a new cast is applied. Range of motion is reassessed and each cast is set within the new range of motion. The length of the casting process is variable and somewhat difficult to predict. We continue with the casting process until our goal for range of motion is reached, until we have reached maximum gains in muscle length, or if gains can be sustained with use of a brace instead. On average this process can be anywhere from 4 to 12 weeks long.
Once the casting period is over, it is typically recommended that the child continue with use of appropriate bracing (which likely will include night time splints) in order to retain gains. Further, the child must continue with a home exercise program to continue to address functional goals and prevent re-emergence of muscle tightness.
Serial casting can be an appropriate and effective intervention for children who walk on their toes or children who tend to hyperextend their knees when walking. Both can be related to a lack of range of motion at the ankle joint. Serial casting can also be appropriate for children who have difficulty donning braces (AFOs) or tolerating use of braces due to a lack of range of motion at their ankles or for children where limitations in range of motion make supported standing difficult.
The following are some (but not all) diagnoses where serial casting may be indicated:
Most children will be casted while positioned comfortably lying on their stomachs. Some may be casted while in a sitting position. It is important to bring something to help keep your child distracted and entertained during the process. Often music or a movie can do the trick!
Our casts begin with a cotton stockinette and padding for comfort and protection of bony prominences. Casts are then fabricated with a combination of soft cast material, plaster, and fiberglass. In most cases, both feet are cast. One of the benefits of our casts is that they can be removed at home without need for a cast saw. Your physical therapist will review instructions for safe cast removal with you.
Families will be educated in safe cast monitoring and management prior to beginning the casting process. The child will be provided with cast shoes to allow for standing and walking. Parents/guardians should monitor for any signs that might warrant cast removal including: signs of impaired circulation, odor from casts, refusal to weight bear, or leg spasms. Casts can not get wet and if wet must be removed immediately. We recommend using sponge baths or obtaining an effective cast cover.
You can expect your child should be able to crawl, kneel, stand, and walk in their braces. In fact, it is expected that the child engage in regular standing or walking in their casts if that is functionally appropriate for them. If your child regularly navigates stairs, you can expect that they may need more assistance or guarding for safety with casts donned.
Serial casting can be an important component of a comprehensive plan of care for your child at NAPA Center. For most children that would benefit from serial casting, it can and should be combined with other interventions such as strength training, balance training, functional electrical stimulation (FES), whole body vibration, gait training, and bracing among others.
Think your child may benefit from serial casting? Ask your physical therapist for more information!
Ryan, E.D.; Beck, T.W.; Herda, T.J.; Hull, H.R.; Hartman, M.J.; Stout, J.R.; and Cramer, J.T.: Do Practical Durations of Stretching Alter Muscle Strength? A Dose-Response Study. Medicine & Science in Sports & Exercise, 40, 1529-1537, 2008. https://doi.org/10.1249/MSS.0b013e31817242eb
Tardieu, C.; Lespargot, A.; Tabary, C; and Bret M.D.: For how long must the soleus muscle be stretched each day to prevent contracture? Dev Med Child Neurol, 30(1): 3-10, 1988