Pilot Study for a Dynamic Testing for Intraoperative Diagnosis of Scapholunate Instability in Patients With a Concurrent Distal, Intra Articular Radius Fracture - A Prospective Clinical Trial

Radius fractures are the most common fractures in adulthood and account for approximately 17.5% of all fractures. The most common distal radius fractures are approximately 57-66% extra-articular (AO type A), followed by completely articular fractures (AO type C) with 25-35% and the least rare partial articular fractures (AO type B) with 9-15%.

The fracture mechanism of distal radius fractures is in most cases a fall on the extended wrist, less often a high-energy trauma. It is not uncommon for there to be additional accompanying ligamental injuries, which are easily overlooked.

5-64% of intraarticular radius fractures are accompanied by injuries of the scapholunary ligament. However, most of these studies are carried out in smaller series, with only one exception. A scapholunary band lesion can occur in isolation or in combination with a distal radius fracture, scaphoid fracture or perilunary luxation. The prevalence of this ligament injury has not yet been sufficiently studied. Acute scapholunary ligament damage accompanying injury to a distal radius fracture, clinical testing of instability by means of the Watson provocation test is not possible due to pain. Thus, scapholunary dissociation is often initially overlooked. Additional later examinations by means of MRI or arthroscopy are necessary to diagnose the missed ligamentary injuries.

In 5-10% of cases, intraarticular radius fractures are associated with complete ruptures of the dorsal scapholunary band, which leads to symptomatic carpal instability with the simultaneous presence of a rupture of the dorsal ligamentum intercarpale (DIC). The number of untreated SL band lesions in distal radius fractures is largely unknown.

A scapholunary band lesion can be represented in different degrees of severity, depending on the still preserved portion of the scapholunary ligament and the surrounding extrinsical ligaments. Partial ruptures only lead to pain during movement and result in a slight restriction of scaphoid mobility. A scapholunary complete rupture, on the other hand, leads to a dissociation of ossa scaphoideum and lunatum, resulting in a Dorsal Intercalated Segment Instability (DISI). DISI malposition in turn leads in the long run to wrist osteoarthritis, called SLAC Wrist, with secondary development of osteoarthritis. The development of the full disease takes 10-20 years. The development of a SLAC Wrist can be counteracted preventively in which a scapholunary instability - also within the framework of a radius fracture - is detected at an early stage and correctly stabilized. However, the clinical relevance and the recommended treatment of scapholunary band rupture has not yet been definitively clarified.