Introduction <p>While stenosing tendovaginitis of the first extensor tendon compartment is frequently encountered in hand surgical practice, similar pathologies in other extensor tendon compartments are rare and can, thus, be overlooked or misdiagnosed. This case report aims to point out the relevance and intricacies of these pathologies.</p> Case <p>This report presents a case of posttraumatic stenosing tendovaginitis of the fourth extensor tendon compartment, developed five months after suffering a crush injury to his index finger with simultaneous stump trauma to the dorsal wrist. The patient’s main symptoms were a progressive, painful swelling of the dorsal wrist combined with the inability of simultaneous wrist and finger extension and impaired wrist extension while forming a fist. While initial diagnostics, including an MRI, pointed towards a partial extensor tendon injury, the intraoperative findings demonstrated a stenosing tendovaginitis of the fourth extensor tendon compartment. This was treated with synovectomy and Z-plasty of the extensor retinaculum. Twelve weeks postoperatively, the patient had returned to work and was free of pain. A 45° dorsal extension was possible with the fingers forming a fist; with extended fingers, 10° of the wrist extension was possible.</p> Conclusions <p>This case highlights a rare pathology and underscores the critical importance of thorough intraoperative diagnostics, particularly the assessments of mobility, to correctly identify underlying pathologies and adjust the surgical approach accordingly.</p> Level of evidence <p>IV Case Report.</p>