Serial casting is a non-surgical, conservative treatment method used to gradually increase the available range of motion in a joint, most often in the arms or legs. This technique involves applying a series of rigid casts that hold a limb at a gentle, prolonged stretch. The term “serial” refers to the fact that the cast is removed and a new one is applied repeatedly over a period of weeks. The goal is to progressively realign the joint and lengthen shortened soft tissues like muscles and tendons. Serial casting provides a continuous, low-load stretch that cannot be achieved with manual stretching alone.
Conditions Treated by Serial Casting
Serial casting is chosen when muscle tightness or contractures limit a person’s ability to move a joint fully, impacting their function. This method addresses stiffness caused by a variety of conditions, both congenital and acquired. Congenital conditions like clubfoot and metatarsus adductus often require this gradual, sustained stretching to reposition the foot into a more typical alignment.
Acquired stiffness resulting from neurological issues is also frequently managed with serial casting. This includes contractures stemming from conditions such as cerebral palsy, spina bifida, stroke, or traumatic brain injury, which can cause increased muscle tone or spasticity. Improving the range of motion prepares the limb for further rehabilitation and can sometimes delay or prevent the need for invasive procedures like surgery. The process aims to correct joint alignment and improve walking efficiency or fine motor skills.
The Step-by-Step Application Process
The serial casting procedure begins with a detailed assessment by a physical or occupational therapist to measure the current range of motion and define specific treatment goals. The limb is then carefully positioned to achieve the maximum degree of stretch that is comfortable for the person at that moment. Proper positioning is followed by the application of a soft cotton stockinette and layers of padding to protect the skin and bony prominences from pressure and irritation.
Next, the casting material, which can be plaster or fiberglass, is wrapped around the limb. The therapist meticulously molds the cast to hold the joint in the newly achieved position of stretch. The cast must then dry and set; patients are usually advised not to put weight on the limb during this time. Once hardened, the cast provides a firm, static hold that maintains the muscle and tendon in a lengthened state.
This sustained, gentle stretch drives biological changes within the soft tissues. Prolonged immobilization in a lengthened position encourages the body to add new sarcomeres, the basic contractile units of muscle fibers, in series. This results in a lasting structural lengthening of the muscle. The sustained tension also helps to unfold and temporarily realign collagen fibers within the surrounding connective tissues and fascia.
The cast is worn for a prescribed period, usually between five and ten days. At the next appointment, the old cast is removed, often using a specialized vibrating saw that does not cut the skin. The therapist re-measures the joint to confirm the gain in motion and applies a new cast, setting the joint at the new, greater maximum stretch point. This incremental process is repeated, often for a total course of four to eight weeks, until the targeted range of motion is achieved.
At-Home Care and Treatment Goals
While the cast is in place, careful at-home monitoring is necessary to ensure safety and comfort. Caregivers are instructed to check the fingers or toes frequently for signs of impaired circulation, such as changes in color or temperature. A blanching test, where pressure is applied to the skin and the pink color should return within three seconds, is a simple way to check blood flow.
Skin hygiene and cast protection are also significant parts of the home care routine. The cast must be kept completely dry, which requires covering it with plastic during bathing or opting for sponge baths. Any bad odor coming from the cast or the development of severe pain should be reported to the treatment team immediately, as these may signal skin irritation or an infection beneath the cast. While mobility may be altered, people are generally encouraged to continue with most daily activities, often using specialized cast shoes or grip socks to allow for standing and walking.
The ultimate treatment goal is to achieve a functional range of motion that improves the person’s ability to participate in daily life activities. Once the full series of casts is complete and the desired flexibility is gained, the focus shifts to maintaining the corrected position. This transition typically involves fitting the person with a permanent brace or orthotic device, such as an ankle-foot orthosis (AFO), which is worn during the day or as a night splint. Ongoing physical therapy and a home exercise program are routinely recommended to strengthen the newly lengthened muscles and prevent the recurrence of tightness.