Mayfield Perilunate Instability Pattern

Mayfield et al described the pattern of perilunate injury when extension, ulnar deviation, and intercarpal supination stress was applied to the wrist. They divided the injuries into 4 stages based on the magnitude and duration of loading.

• Stage I: There is rotatory subluxation of the scaphoid caused by acute dorsiflexion of wrist with resultant injury to the scapholunate ligament. Look for signs of scapholunate dissociation. Also, look for associated distal radial fractures.
• Stage II: Perilunate dislocation. Look for a triangular lunate on the frontal view. On the lateral view, there is slight anterior rotation of lunate and posterior subluxation of other carpal bones with respect to the lunate. Look for associated scaphoid waist and ulnar styloid fractures.
• Stage III: Midcarpal dislocation is the result of ligamentous injury to the lunotriquetral ligament. There is a triangular appearance to the lunate on the frontal view (similar to the lunate dislocation). The lateral view shows dorsal dislocation of the capitate and volar tilt and subluxation of the lunate (i.e., neither the lunate or capitate is aligned with the radius).
• Stage IV: Lunate dislocation from the radiolunate fossa. There is volar dislocation and anterior rotation of the lunate, which gives a triangular appearance to the lunate on the frontal view. On the lateral view, the capitate remains aligned with the radius, but the lunate is dislocated volarly from the radiolunate fossa.

References

Mayfield JK, Johnson RP, Kilcoyne RK. Carpal dislocations: pathomechanics and progressive perilunar instability. J Hand Surg Am. 1980 May;5(3):226-41.