Cascia
Stem cell therapies have been used in the field of orthopedics more than any other.
This should not be a surprising result given that the source of stem cell is
most frequently the bone marrow of the pelvis, and many orthopedic surgeries
involve the hip or lower extremities.
The principal indications for cellular therapy in the orthopedic field to date have been:
Most simple fractures heal within 8-12 weeks when properly managed. Unfortunately, when there is severe trauma or an underlying medical condition that impairs healing, such as diabetes or a history of smoking, the case can result in non-union fracture such as the case shown below.
The case below was that of a 38 year-old craftsman working to restore an architecturally significant cathedral who slipped off the scaffolding fell onto a stone floor 20-feet (6 meters) below. The impact caused a severe fracture of the tibia that did not heal despite three attempted repairs. The image shows numerous titanium bone screws with broken heads. The individual had been off work nearly a year at this point, and the surgeons and the insurance company were discussing the need for amputation.
The insurer, eager to avoid a long-term disability claim, agreed to fund a fourth attempt at repair. The surgeon removed all of the previous fixation devices and inserted a new plate. The stem cells were impregnated into the white synthetic bone matrix and the material was packed around the fracture.
The image below was taken 12 week post-surgery. The fracture line is resolved and a callus has formed around the fracture line. After a short period of physical rehabilitation, the patient returned to work.
Spinal fusion surgeries are used to address chronic low-back pain which is
often caused by deterioration of the intervertebral disc. In the fusion
procedure, the surgeon removes the remnants of the damaged disc and fuses two
or more adjacent vertebrae together, generally with the assistance of a metal
cage that acts as a spacer where the disc is remove, or by use of a rod and
screw system. In either case, there is a need to stimulate bone grow in
order to cause the bones to grow together.
Surgeons traditionally used autograft material. Autograft is obtained by making an incision over the pelvis and scraping out the spongy bone material with a surgical instrument. This is a reliable way to harvest bone marrow, but it extends the time the patient is under anesthesia. Some patients report complications after graft harvest if there are problems with the harvest site healing, essentially leaving the patient with an unhealed section of bone.
A popular alternative to autograft is to use a bone morphogenetic protein. The protein is produced in a pharmaceutical factory and is dispensed directly onto the site where the surgery is taking place. While this approach is highly effective in producing robust bone growth, these products have a history of significant side effects including significant swelling at the site of administration. This makes recombinant proteins less suitable for fusions other than in the lower back.
Cellular therapies work as well as autograft, but without the risk of side effects. Since bone marrow cells are harvested with a needle rather than by cutting into the pelvis, there is significantly less trauma to the patient, and the surgeon can elect to perform that part of the procedure without general anesthesia.
The population in most developed countries is rapidly aging, but due to longer life spans and more active life styles, many are living long enough to develop cartilage defects. The cartilage on the articular surface of the joint, such as the knee shown at right, wear through such that the bone of the distal end of the femur is rubbing directly against the cartilage of the tibia, causing tremendous pain. The underlying cause of the cartilage defect is poor blood supply from the underlying bone, and when the bone becomes necrotic the cartilage collapses due to a lack of support. While the image shows a knee joint, a similar phenomenon happens frequently in the hip.
The traditional approaches have been to install a prosthetic joint, either a hip or knee, or do perform a chondroplasty procedure. Inserting an implant has become a very common procedure, especially with older patients, and implants generally provide a satisfactory solution for the patient. However, implants have a limited life span and must be replaced periodically, usually every 15 years or so. This is not an issue if the patient is quite elderly, but if an implant is placed into a younger patient they might outlive one or more implants, which becomes increasingly problematic as more bone is lost every time an implant needs replacement.
The alternative for younger patients is a chondroplasty procedure. A sample of the patient's cartilage is removed and is sent to a facility where the cells are expanded by a culture process, and the expanded cells are returned to the hospital in a few weeks for implantation. Some patients require two units of the material which doubles the cost of the material, and the surgery itself is a separate expense.
An alternative is to use stem cells to repair the osteonecrosis. The necrotic bone is removed and cells are implanted along with bone matrix that allows the joint to heal. With a renewed blood supply providing nutrients to the cartilage itself, the tissue can repair itself without the need for further surgery.