An In-Depth Look at Joint Fusion

177854220The artificial induction of joint ossification between two bones known as arthrodesis, or joint fusion, is one of the most effective surgical arthritis treatments currently available to patients. Surgeons may also perform arthrodesis in cases of disruptive fractures. Despite the procedure’s prevalence, there are a number of different approaches that may be taken when it comes to joint fusion.

When Is Joint Fusion Indicated?
The first question in arthrodesis is determining which candidates are most ideal for the surgery. Conservative treatments, including splints and medications, should be less effective or ineffective, having been outstripped by the symptoms.

  • Larger joints that fail to respond to conservative treatments, such as the hip or the knee, see greater success from arthroplasty (joint replacement) rather than arthrodesis.
  • The ankles and wrists are common target areas for arthrodesis, as well as the spine. For the purpose of this article, wrist fusion will serve as the primary example.

The goal for recovery is a major factor that needs to be taken into consideration in determining candidacy for arthrodesis. For example, although the patient can expect pain relief and improved joint strength after surgery, these benefits do come at the necessary cost of permanent limited range of motion and loss of flexibility. If movement is more important than strength in order to preserve the patient’s expected quality of life, joint replacement may be indicated instead.

Differing Strategies in Arthrodesis
Wrist arthrodesis is unique because while most joints are comprised of two bones, wrist fusion may involve a dozen bones or more. The wrist has a number of small joints, many of which may become affected by arthritis. In advanced cases, joint alignment and deformity may be present; arthrodesis prevents further deformation and realigns the joint. Ideally, the carpals, metacarpals and radius are fused into a single bone, which still allows for hand rotation if not wrist articulation.

There are several different strategies that surgeons may use to achieve this goal:

  • Bone Autograft: A bone graft may be taken from the patient’s own body, typically harvested from the ribs, hip or leg. Autograft bone has a very low rate of complication, and is osteoinductive as well as osteoconductive. This is often the preferred choice for hand and wrist surgeons.
  • Bone Allograft: Donated from a bone donor bank, allograft bone is more prevalent than autograft bone and will not require the patient to recover from simultaneous surgical sites (the donor site and the fusion site). Allograft bone is often irradiated and freeze-dried prior to deep storage, which kills the living bone and bone marrow cells in order to reduce immunogenicity yet still retains osteoconductive properties. Some forms of processing also preserve osteoinductive proteins.
  • Synthetic Bone Substitutes: For use strictly as an osteoconductive matrix, a number of synthetic bone substitutes are available. The most well-known of these is DBM (Demineralized Bone Matrix), which is an extraction from allograft bones that consists of protein, collagen and growth factors. Ceramic, graft composites, metal plates, screws and wires, and even coral have all been used as bone substitutes in arthrodesis.

A combination of the above is often employed for more comprehensive results. During surgery, the graft is held in place with metal plates, screws and wires to promote fusion in the proper position. The healing process may take over a year before the bones are fully fused, and regular follow-up and physical therapy are recommended throughout that time.

As an arthritis treatment, wrist fusion has a high post-operative satisfaction rate. Joint friction and inflammation are resolved, and painful symptoms are relieved for a higher quality of life.

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