Sequence of perilunate ligament injury

Perilunate ligament injuries generally progress in four sequential stages (represented by the numbers in the image above), depending upon the force involved. In stage 1, the scapholunate ligament ruptures. While this causes instability between the scaphoid and lunate, dislocation rarely occurs. In stage 2, the capitolunate ligament ruptures and the capitate sometimes dislocates. In stage 3, the lunotriquetral ligament ruptures and the lunate dislocates dorsally, but the lunate remains aligned with the radius when seen on an anteroposterior radiograph. Stage 4 injury involves volar dislocation of the lunate into the carpal tunnel.