Certified Hand Therapist (CHT) Practice Exam

How can Boutonniere deformity be distinguished from Pseudo-boutonniere deformity?

1. By DIP active instability

2. By significant ORL tightness

3. By consistent flexibility of the PIP joint

4. By radial nerve function

The correct answer is: By significant ORL tightness

Boutonniere deformity and Pseudo-boutonniere deformity can be distinguished based on the presence of significant tightness of the oblique retinacular ligament (ORL). In Boutonniere deformity, there is an actual structural deficiency and disruption of the central slip, leading to a characteristic flexion at the proximal interphalangeal (PIP) joint along with hyperextension at the distal interphalangeal (DIP) joint. This results in changes in the tension and function of associated structures, including the ORL. In contrast, Pseudo-boutonniere deformity does not involve a true rupture of the central slip but rather an alteration in the position or function of the surrounding soft tissues. The ORL in this condition can exhibit significant tightness, but the PIP joint’s range of motion may be more intact, influencing the overall mechanics and appearance of the finger. Thus, assessing for significant ORL tightness helps practitioners determine if the condition is true Boutonniere or a variant like Pseudo-boutonniere. Identifying this characteristic leads to a better understanding of the management and rehabilitation needs of the affected finger.