Comparative Analysis of 3 Techniques of Scapholunate Reconstruction for Dorsal Intercalated Segment Instability.

PURPOSE

The combination of scaphoid rotatory subluxation, dorsal intercalated segment instability, and dorsal scaphoid translation (DST) constitutes stage 5 scapholunate dissociation in the modified classification system of Garcia-Elias. The purpose of this study was to compare the static radiographic outcomes of reduction and association of the scaphoid and lunate (RASL), three-ligament tenodesis (TLT), and anatomic front and back (ANAFAB) reconstructions for stage 5 scaphoid and lunate malrotation and translation.

METHODS

Stage 5 scapholunate dissociation was created in 15 fresh-frozen specimens by cutting the scapholunate interosseous ligament, long radiolunate ligament, dorsal intercarpal ligament, and scaphotrapeziotrapezoid ligament complex. Specimens were randomized to receive 1 of the 3 reconstructive techniques. Radiolunate angle (RLA), scapholunate angle, scapholunate gap, and DST were measured in static fluoroscopic posteroanterior and lateral views in 3 conditions: baseline, injured, and reconstructed.

RESULTS

Reduction and association of the scaphoid and lunate showed an improved correction of scapholunate gap compared with TLT and ANAFAB. Anatomic front and back demonstrated an improved correction in RLA and scapholunate angle compared with RASL but not TLT. When the reconstruction was compared with baseline, there was a persistent lunate extension for TLT (RLA and scapholunate angle) and RASL (RLA); however, no significant difference in any parameter was found with ANAFAB. Anatomic front and back significantly improved DST, whereas TLT and RASL did not.

CONCLUSIONS

In this cadaveric model of scapholunate dissociation with dorsal intercalated segment instability and DST, each of the 3 repairs had different effects on carpal posture and alignment. While only RASL statistically improved scapholunate gap, only ANAFAB significantly improved DST. Both TLT and RASL improved radiographic parameters; however, each had a persistent increase in the lunate extension following reconstruction.

CLINICAL RELEVANCE

It may be prudent to consider different reconstructive techniques for different stages of scapholunate instability. Anatomic front and back, a repair that addresses both dorsal and volar ligament stabilizers, provides improved reduction of dorsal intercalated segment instability and DST in stage 5 scapholunate dissociation.