Limb-sparing techniques

In bone cancers of the long bones, such as osteosarcoma and Ewing sarcoma, the priority for treatment is complete removal of the cancer with negative margins. In such cases, limb-sparing surgery is preferred when neurovascular structures are not involved. Limb sparing procedures that may be considered include endoprostheses, autograft, and allograft. Although these are a versatile solution, endoprosthesis have a high failure rate, often requiring reoperation. Infection, loosening of the hardware, implant wear, and soft tissue dehicense all threaten the long term viability of this reconstruction. Cancellous bone does not provide mechanical support for a defect but rather provides a scaffold for new bone to grow in due to its osteoinductive nature and high number of osteogenic factors and cells. In tumors involving the metaphyseal region, the growth plate may be affected by the surgery to remove the tumor. In such cases, there is concern for limb-growth disparities due to the disturbed growth plate. Allografting is the treatment of choice for diaphyseal tumors, small defects, and when the patient is awaiting a custom endoprosthesis. Alloprosthetic composites are flexible in that surgeons can adapt the implants for any situation. == Soft tissue reconstruction ==

Both trauma and oncologic resection can cause a large defect where removal of enough soft tissue, such as skin, muscle, and fat, leads to the limb being threatened. In the case of insufficient soft tissue to cover the bone or vital structures such as vasculature, tendons and nerves, several techniques can be employed to cover the tissue, including local flaps and free tissue transfer. In the lower extremity, the peroneal, posterior tibial, and anterior tibial arteries have all been described as successful sources of propeller flap blood supply. The flap, composed of skin and fascia, is used to cover any exposed vital structures, like nerves or bone. Free flap transfer In cases where there is insufficient local tissue to cover the vital structures necessary, free flap transfer can be considered. In free flap transfer or pedicled flap, tissue from an area of the body where it can be spared is taken with its associated vasculature and reattached at the site of the defect. There are many free flap procedures that can be considered, depending upon the size of the defect and type of tissue needed. Flaps may be muscular, cutaneous, fasciocutaneous, or musculocutaneous and include nerves for innervation. In muscular flaps, only muscle is transferred. Examples include latissimus dorsi, gracillis, and rectus abdominis flaps. == Functional reconstruction ==

When a trauma or cancer involves vital functional structures, such as tendons or nerves, transfer of these structures may become necessary to restore function to the limb. Arthrodesis is performed most commonly on joints of the feet, hands, and spine. Arthrodesis can relieve pain from arthritis and fractures. This is accomplished through the use of orthobiologics such as allografts and autografts. Allografts are done by creating bone grafts from a donor bone bank, whereas autografts are bone grafts from other bones in a patient's body. Arthroplasty Arthroplasty, otherwise known as joint replacement, is a surgical procedure which involves resurfacing, realignment, or removal of bone at a joint interface to restore the joint's function. Arthroplasty is often performed on hips, knees, shoulders, and ankles to improve range of motion and relieve pain from arthritis or trauma. Arthroplasty of the shoulder is one of the most common of these procedures, although it has only been widely used since 1955. Since Gluck never published any results or notes on the procedure, Jules-Emile Pean is credited with performing the first shoulder arthroplasty in 1893. In this procedure, a patient's leg is amputated at the knee and the ankle joint is then rotated 180 degrees and is attached to the former knee joint, becoming a new knee joint Rotationplasty retains the use of a knee joint and provides a better position for a prosthetic limb compared to amputation. == Revascularization ==

Another common limb-threatening condition is poor blood flow to the extremity. Chronic limb-threatening ischemia or critical limb ischemia can occur with peripheral artery disease, where the pathology compromises blood circulation to an otherwise healthy limb. This can lead to numerous complications and both a high mortality and amputation rate. To achieve limb preservation, various techniques can be employed to achieve revascularization in patients with peripheral artery disease and related conditions. Bypass surgery Open bypass surgery can be performed when a vessel is severely compromised and the patient's own vein, or autogenous vein graft, can be identified. Furthermore, use of the patient's own vein demonstrated greater patency, or how open and unobstructed the vein is, and lower rates of re-intervention as compared to prosthetics. Endovascular procedures Endovascular procedures are performed in a minimally invasive manner, where only a small incision is created to access the vasculature and a thin, flexible tube is used to access the site of the disease and perform the procedure. These procedures include percutaneous transluminal angioplasty and atherectomy. Revascularization with free flap In some complex cases, patients may have peripheral artery disease threatening the circulation to a limb in combination with a deep wound that exposes vital structures such as tendon or nerves. For such cases a revascularization procedure, such as bypass grafting, can be combined with a microsurgical free flap in order to achieve both restoration of circulation and coverage of the exposed structures. ==References==