Maintaining flexibility of the knee joint is the single most important goal. The range of motion of the knee joint is used by your surgeon to decide whether to continue lengthening. If the amount of knee flexion (bend) decreases much below 40 degrees, the lengthening may be discontinued unless surgery or therapy can improve the motion. It is also important not to lose the ability of knee extension (ability to straighten the knee) compared with before surgery. Knee flexion contracture can lead to subluxation of the knee (knee coming out of joint). In some cases, a spring-loaded splint (Dynasplint; Dynasplint Systems, Inc., Severna Park, MD) is used to help regain knee extension. If the external fixator extends to the tibia, a knee extension bar can be used to prevent the knee from losing extension. Maintaining flexibility of the hip is less of a problem during femoral lengthening. There is some tendency for the hip to develop a flexion contracture (bend at the hip) and adduction contracture (inner thigh tightness of the muscles). Therefore, hip extension (backward stretching) and abduction (outward stretching) exercises are important to avoid these problems. When the hip develops these contractures, it is more at risk of dislocation. Hyperlordosis (swayback) deformity also develops. Although in some cases, surgery is needed to prevent or treat such problems, it is best to avoid them by aggressive and appropriate therapy. During femoral lengthening, it is important to try to maintain the strength of the hip abductor muscles. These are the muscles that lift your leg to your side. If these muscles are weak, you will walk with a noticeable limp.
During tibial lengthening, the muscles that become tight are the plantar flexion muscles. These are the muscles that attach to your Achilles tendon. They are the muscles you use to stand on your toes and point your foot downward. Therefore, when they become tight and contracted, they prevent the foot from coming up to a normal walking position (90 degrees to the leg). This is called an equinus contracture. It is very important to prevent such a contracture. Therefore, during tibial lengthening, stretching exercises to dorsiflex the foot (push it up above the horizontal) is the most important exercise you can do. In some cases, the surgeon will fix the foot with the external fixator to prevent an equinus contracture. In these cases, it is not necessary to perform dorsiflexion stretching exercises. Because two of the muscles that attach to the Achilles tendon originate from the femur (on the other side of the knee joint), the knee may develop a flexion contracture (may lose the ability to fully straighten). To prevent and treat this, it is important to stretch the knee straight, especially at night. We sometimes use a Dynasplint to prevent or treat a knee contracture during tibial lengthening. The other joint that is important to stretch is the subtalar joint. This is the joint under the ankle that permits your foot to move side to side. Side-to-side stretching exercises of the foot are also important during tibial lengthening. A foot splint should always be used when resting to prevent the foot from dropping or twisting.
Combined Femoral and Tibial Lengthening
This is the most difficult of all the lengthenings, especially for the knee joint. The muscles on both sides of the knee are being stretched by the simultaneous femoral and tibial lengthenings. Hinges usually bridge the fixators across the knee. They help protect the knee from the increased compressive forces of the tight muscles. Combined femoral and tibial lengthening can be performed just as successfully as isolated femoral or tibial lengthening. However, aggressive, intensive, and frequent therapy and home exercises are necessary. The same considerations as those described for femoral and tibial lengthenings are combined to design the therapy program for simultaneous femoral and tibial lengthening.
The goals during humeral lengthening are to maintain the range of motion of the shoulder and elbow. The shoulder rarely gets stiff during lengthening of the humerus, but the elbow may. Therefore, putting the elbow through a full range of motion is the most important exercise. There is just as much tendency for the elbow to get tight during flexion as during extension. It is important to emphasize stretching of the elbow muscles and joint in both directions equally.
The tendency during forearm lengthening is for flexion contracture of the wrist, fingers, and elbow. Therapy is designed to primarily stretch these joints into extension (straightening). If the hand is also fixed by the external fixator pins, more effective range-of-motion exercises can be achieved for the fingers because the wrist is immobilized in a functional position. A Dynasplint is often necessary to prevent or to treat elbow flexion contracture.