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Soft Tissue Damage And Its Orthopedic Manifestations In Rheumatoid Arthritis

21 December 2016 by Hugh Larson

Although many people are aware of rheumatoid arthritis (RA) and its effects on joint surfaces, they may not be aware that damage to a joint's supporting structures can occur. Underlying soft tissue damage may exist well before joint erosions or other radiographic evidence of damage can be seen. Further investigation into pain and loss of function with more sensitive imaging tests is an important tool to minimize or prevent catastrophic joint failures.

Metacarpophalangeal Instability

The metacarpophalangeal (MP or MCP) joints are the prominent knuckles in the hand where the fingers connect to the hand. One hallmark deformity seen in some long-standing or severe RA patients is ulnar drift. In ulnar drift, the fingers begin to drift sideways, eventually pointing toward the pinky-side of the hand. Less commonly, radial drift can occur where the fingers drift toward the thumb. The underlying deformity is a result of damage to the ligaments responsible for maintaining stability of the fingers at the MP joint.

Even before ulnar or radial drift is a noticeable problem in RA, damage to ligaments at the MP joint, mainly the collateral ligaments, can lead to instability of the fingers. When the collateral ligaments are stretched or damaged, they no longer hold the finger taunt when it is bent (in flexion) at the MP joint. This leads to lateral (side-to-side) movement of the finger that would not normally occur.

Atlantoaxial Instability

Possibly one of the most concerning types of soft tissue damage is when RA affects the cervical spine. Specifically, instability between the first two vertebrae, C1 (atlas) and C2 (axis), can result, causing atlantoaxial instability (AAI). The initial symptoms of AAI may include neck pain, inflammation, and stiffness. Over time, nearby nerves can become irritated, contributing to occipital neuralgia and other neurological symptoms, depending on the specific nerve affected. With enough damage, the vertebrae may slip past each other, causing a partial dislocation of the cervical spine (subluxation). Due to importance of the atlantoaxial joint, especially its job of keeping the head attached to the spinal column, the consequences of subluxation can be severe. Paralysis can result from spinal cord compression and may not be reversible.

Sacroiliac Joint Dysfunction

The sacroiliac (SI) joint is often overlooked because it is not a typical joint. Under normal conditions, the amount of movement at the SI joint is slight and is not noticeable. To gain a better idea of where the SI joint is located, it is approximately half-way between your lower back and where your buttocks meets the chair when you are sitting, on each side of the gluteal cleft. The function of the SI joint is to absorb and distribute force from the upper body. In women, the joint typically becomes more mobile during pregnancy to allow the baby to pass through the pelvic bones during a vaginal delivery.

Like other types of soft tissue damage, RA can cause similar damage to the ligaments supporting the SI joints. The SI joints rely on a network of ligaments to restrict unnecessary motion. As these ligaments become damaged, the pelvis moves more than normal at the SI joint, contributing to pain and instability. Due to the location of the SI joints, it is easily confused with pain from the lumbar spine or far posterior hip pain. SI joint pain can also radiate to the groin and/or lower quadrant of the pelvis, further adding to confusion of the exact source of pain.

Although RA is mostly considered with regards to its direct impact on joint surfaces, the same inflammatory processes can cause considerable damage to the soft tissues responsible for holding joints in place. If you have RA and are dealing with serious pain and limitations, despite having little evidence of joint damage, a consultation with an orthopedic specialist can give you more insight into potential soft tissue damage.

For more information about conditions and treatment options, visit websites like http://www.towncenterorthopaedics.com.

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