Arthrodesis term indicates surgically produced fusion of the joint. [ It is important to differentiate from ankylosis which is a fusion of joint or stiffness of joint resulting from a disease process.]
Syndesis or artificial ankylosis are other names given to arthrodesis.
Arthrodesis aims to block the movement of the joint. Therefore painful joint movement is the primary indication for this procedure.
In the spine, it includes blocking of one more vertebral movement is more commonly called spinal fusion.
Indications for Arthrodesis
- Painful diseased joints
- Infection
- Osteoarthritis
- Inflammatory arthritis
- Posttraumatic arthritis or instability
- Tumor Surgery including Joint
- Bone excision could be followed by arthrodesis
- Spinal fusion as a part of surgery in spinal fixation
- Failed arthroplasties
Role of Arthrodesis and Arthroplasty
Before arthroplasty was available, every diseased joint was considered for joint fusion including the major joints like hip or knee joints.
But arthroplasty has changed the outlook. Joint mobility can be retained by choosing arthroplasty over arthrodesis in most of the cases of large joints. Thus, indications to fuse large joints like hip, knee, shoulder elbow, wrist and ankle have reduced drastically.
Evolution of custom-made prostheses has led to increased use of prostheses in tumor surgery too.
However, arthroplasty is avoided in presence of infection.
Small joints of the foot and to a lesser extent hand and wrist can still be well managed by arthrodesis.
The main disadvantage of joint fusion is that it sacrifices the movement of joint. Thus the function of the limb is definitely compromised. For example, in the lower limb, energy requirements for ambulation are increased.
Therefore the fusion is contemplated only in patients in which the advantages outweigh the disadvantages.
Arthrodesis is most commonly performed on joints in the spine, hand, ankle, and foot.
Interestingly, it is also used as the procedure of last-resort in some failed arthroplasties.
Types of Arthrodesis
- Intraarticular
- The joint surfaces are bared and fused.
- Permit greater correction of deformity
- permit removal of diseased bone and apposition of healthy bone
- Extraarticular
- Joint is not exposed
- Fusion is achieved by fusing bone block outside the joint.
- Especially useful in treating children
- Also beneficial where large amounts of necrotic bone or active infection, as in tuberculosis.
- Combined intraarticular and extraarticular.
The Procedure of Arthrodesis
The exact procedure would depend on the joint involved. An outline of the general intraarticular procedure is mentioned here.
The involved joint is opened with a suitable approach and both the articular surfaces are exposed. The cartilage is removed from the joint surfaces along with any necrotic bone if present. Both ends are shaped for maximum compression at the arthrodesis site.
Different joints are kept in different positions depending on the function of the joint and energy consumption for activity. Patient demands some time dictate the position of limb or digits.
After cartilages are denuded enough to find the oozing bone surfaces, the surfaces are apposed together and then fixed with suitable gadgets. Bone graft may or may not be required depending on the joint in consideration.
The basic idea is to induce the fusion the joint in a desirable position and hold the bones in desirable position till the fusion is strong enough to hold without an internal or external implant.
The image shown here shows an intramedullary implant holding the fused joint in position.
Arthrodesis is achieved by putting a bone graft to induce the process of fusion with bone graft while the position of the bones is held securely by internal or external fixation.
In the foot, extraarticular arthrodesis is preferred for some fusions.
Complications of Arthrodesis
Joint fusion surgery carries the risk of all complications associated with the surgical procedure. These are the infection, wound healing issues, and other iatrogenic injuries.
A distinct risk that joint fusion surgery carries is a failure of fusion to occur. Rigid fixation, use of bone graft lessens the risk though. Some sites are more prone to failure than others.
Prognosis
Arthrodesis means loss of one joint and thus increasing the energy expenditure of limb function. Apart from that it also results in the awkwardness of the movement. The patient should be prepared to live with that.
A well-done fusion results in a pain-free stable joint at the cost of the motion of the joint.
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