Muscle Contractures
Contractures occur when the soft tissues cannot accommodate changes in bone length. To treat contractures effectively, one needs to identify the potential problem muscles. In tibial lengthening, for example, the problem muscles are the gastrocnemius and toe flexors. As a result, patients can develop knee flexion, ankle plantar flexion, and toe flexion contractures. In the femur, both rectus femoris and hamstring muscles resist lengthening. This can result in a fixed flexion deformity of the knee and a flexion range of motion deficit. Lengthening of the humerus involves the fewest problems. If problems do arise, they are the result of biceps and brachioradialis tightness. In the forearm, finger flexors tighten more quickly, causing proximal and distal interphalangeal flexion and hyperextension of the metacarpophalangeal joints. Despite these problems, contractures can be treated with the following modalities.
Passive stretching and soft tissue mobilization: Patients should take pain medications 30 minutes before receiving therapy. A muscle is prepared for stretching by applying moist heat for 15 minutes before activity. The antagonist muscle should always be activated before stretching the agonist muscle. The muscle can thereby be relaxed by means of reflexive inhibition. Another effective method of reducing pain during range of motion exercises is to immobilize the skin over the pin site with tight gauze wraps. This reduces skin motion around the pins.
In general, biarticular muscles (muscles that work on two joints) should be stretched 20 to 30 times per session and uniarticular muscles (muscles that work on one joint) should be stretched 10 to 15 times per session. When stretching a biarticular muscle, obtain maximum stretch in the direction opposite that of the muscle action at both proximal and distal joints and hold each stretch for 20 to 30 seconds. Some examples of biarticular muscle stretch include rectus femoris stretch with the hip in full extension and knee flexion and ankle dorsiflexion with knee extension to stretch the gastrocnemius muscle.
Positioning: Optimal maximal positions vary based on the body parts that are affected. For example, patients who are undergoing tibial lengthening should be positioned with the knee extended straight and the ankle flexed up. Knee extension along with hip abduction is a desirable position for patients who are undergoing femoral lengthening. Patients undergoing humeral lengthening need elbow extension. Patients undergoing forearm lengthening require elbow extension (elbow straight), wrist in slight dorsiflexion (bent upward and backward), and finger extension (straight).
Splints: Custom designed splints help to keep the soft tissues (muscles and tendons) stretched properly. Using a splint to place a muscle under tension for as many hours as possible helps prevent contractures by obtaining plastic response in the connective tissue.
Dynamic splinting: In certain situations, we use special dynamic splints. These are different from static splints because they include a spring-like or elastic mechanism to produce elongation of the tissues through a low load prolonged duration stretch. Dynamic splints work most effectively in treating knee and elbow flexion contractures. Note that splints work only in optimal positions and that their tension should always be increased gradually. These types of splints are also often used for the fingers and toes.
Muscle Weakness
In addition to joint stiffness, patients may experience muscle weakness. This is caused by lack of use (because the patient cannot walk normally). Pain can also inhibit muscle function, adding to weakness. The following modalities help in the management of muscle weakness.
Electrical stimulation: Electrical stimulation can be used as an adjunct to a strengthening program and to augment voluntary muscle contraction. To accomplish this, a muscle stimulator machine is applied to the surface of the limb (thigh, for example) and a low level electrical signal stimulates the underlying muscle to contract. Some children do not tolerate this well.
Hydrotherapy (water therapy): Hydrotherapy helps patients avoid significant muscle weakness, especially when both legs are being lengthened. It promotes active range of motion. The natural buoyancy allows simulated weight bearing. The higher the level of the water (chest deep versus waist deep, for example), the more "weightless" one feels. Hydrotherapy also helps in keeping pin sites clean.
Progressive weight bearing: Programs of progressive weight bearing are important during all phases of limb lengthening rehabilitation. During the lengthening phase, patients should be encouraged to perform weight bearing as prescribed. Some patients may experience pain from increased weight bearing, and the increased weight bearing can cause undue stress on the pins or wires. Weight bearing is even more critical during the consolidation phase. The patient should progress from two crutches to one and then to none. He or she should also perform closed chain exercises. (Closed chain exercises are defined as resistive exercises with which the load is applied through the feet; some examples of closed chain exercises are leg press, stair climber, and bicycle). Many patients can walk without assistive devices and have no limp during the latter part of the consolidation phase.
Nerve Injury
Nerve injury occurs primarily in patients who are undergoing tibial lengthening. It happens when certain nerves do not stretch enough to accommodate the bone lengthening. Peroneal nerve symptoms during tibial lengthening are caused by referred pain in the dorsum of the foot. This pain may present initially as hyperesthesia (increased sensitivity) and then as hypoesthesia (reduced sensitivity). Weakness in the muscles that control toe and foot action are sometimes observed. Pain medications usually do not help. Referred pain in the top of the foot is increased with knee extension and is relieved by flexing the knee. When signs of peroneal nerve irritation occur, the use of a dynamic knee extension splint should be discontinued and knee extension exercises should be reduced. A patient who may be developing this condition should notify us as soon as possible. We monitor nerve function using a quantitative sensory testing device called a pressure specified sensory device (PSSD). This device measures tactile sensitivity (feeling ability) for one- and two-point touch. This device often allows us to identify nerve stretch problems even before they cause symptoms. This device does not work reliably in children younger than 6 years. In most cases, reducing the rate of lengthening reduces the symptoms of nerve irritation and the PSSD results return to normal. In cases in which patients do not respond to rate reduction, peroneal nerve decompression surgery is required. This is a small procedure that involves a small incision and, at most, an overnight hospital stay. When indicated, nerve decompression prevents permanent nerve injury and allows the nerve to recover. This, in turn, allows the lengthening to continue.
Physical and occupational therapists play a critical role in limb lengthening and skeletal deformity correction. A successful functional outcome depends on the quality and amount of therapy a patient receives. Success also depends on the involvement of the family members and caregivers. Physical therapists should encourage families and care providers to attend the physical therapy sessions. There, they can learn the optimal positions for stretching and the passive stretching exercises. With team effort, limb lengthening rehabilitation can be successful.
