Hand joints without osteoarthritis maintain their joint space when other joints have or develop osteoarthritis.

Articular cartilage loss is a key feature of osteoarthritis, and many people assume osteoarthritis is a systemic disease of articular cartilage, explains Jeffrey B. Driban, PhD, AT Ret, CSCS. “Several studies have suggested hand osteoarthritis is likely systemic, and people with hand osteoarthritis are predisposed to general cartilage loss,” he says. “However, few researchers have performed longitudinal studies of finger joint space width (JSW), which represents articular cartilage, among people with or without hand osteoarthritis, let alone large studies that could clarify the systemic nature of cartilage loss in hand osteoarthritis.”

For a study published in Rheumatology, Dr. Driban and colleagues sought to determine if normal joints—based on a radiograph—had more JSW loss over 4 years in hands with incident or prevalent osteoarthritis elsewhere in the hand versus hands without osteoarthritis.

Unpooled Effect Sizes Were Measured to Interpret Differences

In a cohort of 3,368 patients from the Osteoarthritis Initiative, the researchers measured  JSW in the distal and proximal interphalangeal joints. Patients underwent baseline and 48-month hand radiographs; 16 hand joints were scored (including the thumb base) for Kellgren-Lawrence (KL) grade. A joint with a KL grade greater than 2 was determined to have osteoarthritis.

Three groups were classified based on longitudinal hand osteoarthritis status:

1. No hand osteoarthritis (KL<2 in all 16 joints) at the baseline and 48-month visits.
2. Incident hand osteoarthritis (KL<2 in all 16 joints at baseline and >1 joint with KL>2 at 48-months).
3. And, prevalent hand osteoarthritis (>1 joint with KL>2 at baseline and 48 months).

“We then compared if JSW in radiographically normal joints differed across these three groups,” Dr. Driban says. “To help interpret the differences between groups, we measured unpooled effect sizes.”

The study team observed that hand joints without osteoarthritis maintain their joint space when other joints have or develop osteoarthritis. “We noted small differences in JSW loss that are unlikely to be clinically significant between radiographically normal joints and those without hand osteoarthritis (n=1,054) and those with incident (n=102) or prevalent hand osteoarthritis (n=2,212) (effect size range: -0.01 to 0.24),” Dr. Driban says.

Local Conditions May Elicit Cartilage Loss in Osteoarthritis-Suspected Joints

The incidence of significant change was observed in JSW among radiographically normal joints across the three groups, which ranged from 3% to 10%, regardless of group, according to the study team. “These findings were consistent when we excluded [people] with a history of a hand fracture or limited the group with no hand osteoarthritis at both visits by excluding hands with [a] KL grade of 1 in any joint at either visit (Table),” Dr. Driban notes.

He adds that “local conditions (eg, excessive joint loading or injury) may contribute to cartilage loss in a susceptible joint. Just because one joint is affected doesn’t mean the other joints in the hand will also have [JSW] loss. Now that we have evidence that osteoarthritis in finger joints doesn’t relate to [JSW] in other joints, it is important to understand when joints experience [JSW] loss during different stages of osteoarthritis development and progression.”