89 Troublesome Lunate Facet
89.1 Introduction
In recent years, the treatment of distal radius fracture has seen a significant change in trend, moving away from conservative treatment toward surgical treatment. With the introduction of fixed-angle plates, and ultimately also multidirectional fixed-angle plates, it was possible to solve many of the problems related to osteoporosis and severely comminuted fractures. Palmar fixed-angle plate fixation now represents the preferred method of osteosynthesis and allows long-term anatomical retention of the articular surface, especially in the cases of intra-articular involvement.
However, we still see anatomically reduced and fixed fractures, where during follow-up severe displacement occurs. Especially the lunate facet is of special importance as it represents the area where the strong radiocarpal ligaments insert, which stabilize the carpus. Fractures in this area can be diagnosed as ligament avulsion leading to instability of the proximal carpal row due to lack of bony and ligamentous support. If these fragments are not properly fixed, a high risk for secondary dislocation with carpal subluxation may lead to significant problems. Depending on the size of these fractures, lunate facet and palmar rim fractures are classified.
To detect and adequately treat these fracture patterns, CT scans are mandatory as these fractures are often underestimated and options for conservative treatment are lacking. Standard palmar plates are unable to safely capture and support these fragments. Special devices have been developed for the lunate facet by the watershed plate design and flexor pollicis longus (FPL) plate design (see ▶Fig. 89.6), where the special shape allows mounting the plate far distally avoiding the risk for flexor tendon irritation. Palmar rim fractures, however, cannot be stabilized by single plates and need additional fragment-specific fixation by small screws or hook plates.
In the case of secondary dislocation with carpal subluxation, decision-making for treatment may be difficult. Early revision with anatomical restoration is indicated, however, as it is challenging. Alternatively, early salvage procedures by partial radiocarpal fusion may be performed.
89.2 Patient History Leading to the Specific Problem
A 42-year-old man sustained an intra-articular distal radius fracture with involvement of the lunate facet (▶Fig. 89.1).
89.3 Anatomic Description of the Patient’s Current Status
Following reduction and cast immobilization, a CT scan was performed, which confirmed the intra-articular involvement and the fractured lunate fossa, however, without severe palmar displacement (▶Fig. 89.2a, b). Fracture fixation was done through the typical palmar approach using a conventional T-plate with one row distally where the postoperative CT scan demonstrated anatomical reduction (▶Fig. 89.2c, d).
Due to increasing pain during mobilization, radiograph control was performed, which surprisingly demonstrated secondary dislocation with palmar subluxation of the whole carpus and the palmar rim (▶Fig. 89.3). Additionally, the situation was checked by CT scan demonstrating subluxation of the carpus over the distal part of the plate with significant intra-articular step-off (▶Fig. 89.4).
