Clinical implications of peripheral new bone formation in psoriatic arthritis: a literature-based review.

While the destructive changes of peripheral articular damage of psoriatic arthritis (PsA) are extensively studied, the productive modifications have been somewhat neglected. This literature-based study focuses on the clinically relevant aspects of peripheral bone proliferation in PsA. New bone proliferation frequently occurs as juxta-articular and entheseal apposition in PsA patients but also in psoriatic patients without arthritis, the Psoriatic Arthritis Ratingen Score is the only radiographic method to evaluate peri-articular new bone formation, numerous ultrasound systems to score entheseal changes have been proposed, several serum biomarkers of bone-turnover have been associated with PsA and psoriasis but they do not have clinical relevance. The effects of the biologics on peripheral new bone formation remains to be elucidated as well as the contribution of peripheral bone apposition to disability. Many aspects of peripheral osteoproliferation in PsA have not yet been properly addressed and represent clinical unmet needs of this rheumatic disorder.