Bone transport is a specialized surgical technique designed to regenerate new bone tissue, addressing significant bone defects or discrepancies. This method helps patients restore limb length and function, playing a significant role in modern reconstructive surgery. It aims to restore the natural continuity of bone, improving mobility and overall quality of life.
Understanding Bone Transport
Bone transport operates on the biological principle of distraction osteogenesis, where new bone forms as bone segments are slowly pulled apart. This technique harnesses the body’s natural capacity to heal and grow bone tissue. A surgical cut, known as an osteotomy, creates movable bone segments. These segments are then gradually separated, stimulating the growth of new, immature bone, often referred to as callus, in the gap created.
The method involves applying controlled tension across the site of the surgically disrupted bone while it heals. This gradual stretching encourages the formation of new bone and also expands surrounding soft tissues like skin, blood vessels, nerves, and muscles. The concept gained prominence through the work of Gavril Ilizarov in the 1950s, who refined the technique for long bones. This approach allows for new bone creation without harvesting bone from another part of the body, offering a distinct advantage in reconstructive procedures.
Conditions Treated by Bone Transport
Bone transport is a versatile treatment option for several complex orthopedic conditions involving substantial bone loss or deformities. It is frequently employed to address significant bone defects resulting from severe trauma, such as high-energy open injuries, or where bone has been removed due to chronic infections like osteomyelitis or after tumor removal.
The technique is also effective in correcting limb length discrepancies, where one limb is noticeably shorter than the other, whether due to congenital conditions or acquired injuries. It is also a viable solution for non-union fractures, which are fractures that have failed to heal naturally despite conventional treatments.
The Bone Transport Process
The bone transport process unfolds in distinct phases, each carefully managed to promote new bone formation and maturation. It commences with an osteotomy, the initial surgical step where the bone is precisely cut to create the segment that will be moved. This creates a controlled fracture that initiates the bone healing cascade.
Following the osteotomy, a latency period of approximately 5 to 7 days is observed. This short phase allows for the initial formation of a soft callus at the osteotomy site, mimicking the early stages of natural fracture healing. This sets the stage for new bone growth.
The distraction phase then begins, involving the gradual and controlled separation of the bone segments. This is achieved by activating an external or internal fixation device, adjusted at a rate of about 0.75 to 1 millimeter per day, often in multiple small increments. This slow, continuous tension stimulates the growth of new bone within the widening gap.
Once the desired length or gap closure is achieved, the consolidation phase begins. During this period, the distraction device remains in place, but no further distraction occurs. The newly formed, soft bone gradually hardens and matures, mineralizing over several months to become strong and able to bear weight. This phase is generally longer than the distraction phase, often lasting two to four times its duration, allowing for robust bone formation and remodeling.
Life After Bone Transport
Life after bone transport involves a dedicated period of recovery and rehabilitation. The duration of treatment can be lengthy, with patients often wearing external fixators for 6 to 12 months, varying based on the extent of bone regeneration and individual healing rates. For every centimeter of bone gained, it generally takes about one month for new bone to form and mature.
Pain management is an important aspect of post-operative care, and patients receive instructions on how to manage discomfort. Physical therapy is a fundamental component of rehabilitation, often beginning immediately after surgery to prevent joint stiffness and muscle atrophy. This therapy focuses on regaining strength, improving range of motion, and restoring normal function in the affected limb.
Patients and their caregivers are also instructed on specific care routines, such as pin site care for external fixators, to prevent infection. Common challenges during this period include potential stiffness in nearby joints and the psychological burden associated with prolonged treatment and external devices. Once the new bone has fully consolidated, the fixation devices are removed. Most patients can gradually return to their normal activities within a few months after the full treatment course.