[Ulna Impaction Syndrome - a critical review of the literature]

Ulnar impaction syndrome (UIS) is a frequent diagnosis for ulnar-sided wrist pain, traditionally understood as a mechanical overload condition resulting from positive ulnar variance. Established treatments typically focus on osseous decompression, primarily through ulnar shortening osteotomy (USO) or the arthroscopic wafer procedure (AWP).

This review critically evaluates the classical biomechanical paradigm of idiopathic UIS based on current literature, epidemiological data, and clinical outcomes.

Current evidence demonstrates that congenital positive ulnar variance and degenerative lesions of the triangular fibrocartilage complex (TFCC) are both very common in the asymptomatic general population and therefore do not represent an obligate pathology. Furthermore, the radiological measurement of ulnar variance is subject to methodological inconsistencies. The premise that structural overlength is the sole pain generator necessitating osseous correction is contradicted by the high clinical success rates of conservative therapy and isolated arthroscopic TFCC debridement. While USO and AWP can yield good clinical outcomes, USO in particular is associated with high complication and reoperation rates of up to more than 60%, predominantly due to hardware irritation and non-union.

Congenital UIS is likely overdiagnosed and overtreated due to non-specific diagnostic criteria. A rigorous exclusion of differential diagnoses is mandatory. Management should be approched step-by-step. Initial therapy should consist of conservative measures or isolated arthroscopic soft-tissue debridement. Due to their substantial complication profiles, osseous shortening procedures should be strictly indicated and reserved exclusively for refractory cases.