Leg Length Discrepancy
Ringed External Fixator
Ringed external fixators use rings outside the body, connected to the bone through wires and pins that are surgically placed. With these external fixators, it is possible to control movement of the bone from outside the body with limited need for incisions. The rings outside the body are most often made of light weight metals such as aluminum or titanium.
Some brands have started using carbon-fiber as the ring material as it is stiff to allow for proper manipulation and control of the bone, while not blocking x-rays which are required to evaluate bone position during treatment. At least two rings are used, one into each bone on either end of where the bone cut is performed. These rings are then connected to each other via struts, which historically were solely straight, but more recently allow for multi-directional movement between rings.
Current day ring external fixators have numerous uses within the field of orthopedics. They allow for manipulation of bone through small minimalistic incisions which is ideal in patients with poor healing capabilities. They also allow for bone lengthening and deformity correction in all planes and including rotation. The main issue with ringed external fixators for patients is that often they are not strong enough for weight bearing, so patients require crutches or wheel chair use while undergoing treatment. Other issues include high rates of pin site infections and patient psychological coping with having the external fixator on their body.
The surgical treatment for limb length discrepancy relies on the bodies natural ability to heal fractures. Doctor Ilizarov was a Polish born Soviet physician who in the 1950s and 1960s developed a ringed external fixator system for the treatment of orthopedic injuries. Through his extensive scientific work, he found that if a bone is cut and the two bone ends are moved apart at the correct rate, the body will fill the gap with new bone. This technique is now called distraction osteogenesis. During your evaluation with your surgeon, he or she should use xrays and physical examination to determine the cause for and where exactly the leg length discrepancy originates from. Trauma typically results in the shortening of one bone, while congenital etiologies of leg length discrepancy can affect both the tibia and the femur.
To ensure proper cosmetic and physiologic final outcome, it is important to lengthen the correct bone. Ideally the knee joint stays at the same level as the contralateral leg at their final leg length. However, at times other factors can require asymmetric lengthening of the leg bones. The amount of lengthening performed is usually dictated by what the patients body allows. While the bone lengthens, soft tissues include muscles, ligaments, arteries and nerves do not grow or length at the same rate. If you lengthen too far, then you can cause complications associated with these other structures being stretched to include nerve damage and joint contractures. Often patients undergoing limb lengthening require daily at home or in person physical therapy to prevent some of these complications.
Leg Length Discrepancy
Limb length discrepancy is a common occurrence in the general population with many people being completely asymptomatic. It is generally accepted that up to 1 inch of difference in one leg from another is not noticed by patients. However, some patients have much larger differences of several inches or more between legs. Leg length discrepancy can result from multiple causes including congenital reasons, trauma, infection or paralytic disorders. The root cause for most of these is either premature closure of growth plates or congenital reasons why a bone doesn’t grow properly.
Discrepancy in leg length can result in back pain, osteoarthritis, functional scoliosis, toe-walking contracture of the ankle, and inefficient gait. Treatment for leg length discrepancy varies based upon the severity. For some patients it’s as simple as a shoe insert or custom-made shoe which corrects the difference. While other patients may require a special prosthesis similar to an amputation prosthesis to gain enough length to be able to stand or walk on both feet. Surgical treatment when caught in children can include preventing the longer leg from growing it its full height, thereby limiting the leg length discrepancy. Another surgical option is for leg lengthening, which can be achieved through multiple surgical options.
Stryker Hoffmann LRF is at the forefront of technology for ringed external fixators. They have designed the only radio-opaque ring which doesn’t block xrays, and optimized the configurations possible on the rings. The accessory components that attach to the ring are highly advanced in design meaning the system as a whole requires less components while providing the same stability and function in the system. While some of these systems are complex and difficult to use, Stryker has worked to make their system as simple and user friendly as possible. This ease of use allows for shorter operative times for patients.