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When the surfaces of a small joint in the fingers are destroyed, they can be replace by artificial surfaces or by interposing another tissue between the bones to stop the painful bones from rubbing (if movement possible) or to allow better movement and realign the the bones to a more anatomical appearance.
The joints can be destoyed by arthritis,
- inflammatory - rheumatoid, psoriasis etc.
- degenerative - osteoarthritis
- traumatic - after a fracture into the joint, or ligament tear going on to malalignment.
Presentations
- pain - often constant ache but also with episodes of sharp catching or grating
- deformity - the joints thicken, may become angled and often boney lumps grow especially around the end joint
- stiffness - the bone surfaces are roughened and do not allow gliding of one bone over the other
- loss of function - difficulty gripping and picking up small objects
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Xray changes
The xrays demonstrate the loss of joint space (cartlage), the erosion of the bones and the extra lumps of bone forming at the edges of the joint. The overall deformity can be recognised and our aim is to correct all these factors with the joint replacement.
End Joint (DIP)
The end joint or distal interphalangeal joint of the finger is commonly affected by osteoarthritis. Often the first sign is the development of a ganglion, a transparent cyst, at the base of the nail which may cause pressure on the nail bed leading to deformity or ridging of the nail. This commonly is associated with a tiny spur of bone underneath.
As the arthritis worsens the bony growths become larger forming Heberden’s nodes (lumps on the side of the joint), there is loss of joint space, often eccentrically leading to angular and even twisting deformity. Pain may be severe or minimal, but often it is the loss of function (catching the hooked finger) or the “ugliness” of the finger which brings self conscious women to request correction.
Options:
• ganglion excision is easily performed as a day case but it is important to not injure the nail bed beneath any further. In addition there is likely to be less recurrence if the underlying small bony spur is removed at the same time.
• joint fusion is certainly a way to realign the finger, but is fixed either complely straight so that it will not bend (more difficult to get pulp of finger to pulp of
thumb for finger pinch), or in some flexion (may get caught on objects eg. pockets or bedclothes). This is a rigid extension of the middle bone.
• joint replacement has the advantage of maintaining some flexion (about 400) aligning the finger and giving softer sensation to the end of finger with pinch. A small silastic hinge is inserted between the reshaped end of bones, a capsule forms around the prosthesis to stabilise the “joint” and yet still allow movement. The end joint is splinted for 6 weeks postoperatively and may need additional splint for up to 6 months at night for the capsule/ligaments to become mature.
Middle Joint (PIP)
The middle joint or proximal interphalengeal joint may be effected by either osteoarthritis or rheumatoid arthritis. These joints are usually more painful, become swollen and stiff; therefore the management is most often indicated for pain or lack of function, rarely cosmetic. Xrays show the loss of joint space (cartilage), the irregular worn bone, cyst formation and widening of the bones about the joint.
Options
• conservative : the joint can be injected with cortisone in the early stage, anti inflammatory medication may help for a while and a hand therapist may assist with splints and aids by reducing the stress on these joints.
• joint fusion again will reduce the pain and alignment but has the draw back of even more difficulty with a fixed joint getting in the way being either too straight or too flexed at different times. It is considered more in the case of the index finger as this can withstand greater side pressure from the thumb, with thumb index pinch!
• articulated joint replacement can usually provide a 600 range of flexion with proper alignment and ligament reconstruction. Removable splintage is required for 6 weeks but early movement occurs before this time. Although some patients have both end and middle joints affected in the same finger it is advisable not to do them at the same time!
Knuckles (MCP)
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The knuckle or metacarpophalangeal joints may also be involved and are more commonly affected by rheumatoid arthritis than osteoarthritis. The ligaments may become stretched , the lining of the joint swollen, the tendons slip off the joint and deformity occurs as the fingers drift towards the little finger side of the hand. The head of the metacarpal may be destroyed (eroded) and the joint sublux or dislocate. Fortunately these severe cases are seen much less now that control of the disease is better with the more modern medical treatment available.
options
• conservative management includes medication +/- injections to settle the inflammation or synovitis, hand therapy to reduce stress on the joints and splints to rest them.
• soft tissue surgery may be indicated to remove agressive synovitis if not controlled by medication. If there is ulnar drift or early deviation without bone or joint damage, rebalancing the tendon pull or ligaments may slow down the progress of destruction.
• joint replacements. In the higher demand patients with traumatic or osteoarthritis, normally an articulated prosthesis is inserted, but with a low demand patient with severe rheumatoid arthritis, a silastic hinge joint may be considered, together with a rebalancing of the tendons about the joint. In these cases it is not unusual to do more than one joint at the same operation time.
Summary
• finger joints can be replaced for patients with arthritis, which leads to deformity and loss of function.
• they often improve the appearance of the fingers in addition to helping with pain and movement.
• they are an alternative to fusing a painful joint, but are not as robust in patients who have high demands for their hands.
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