Biomechanical comparison of scapholunate reconstruction techniques in a type II wrist model

This study assesses the biomechanical changes following scapholunate interosseous ligament rupture and subsequent surgical reconstruction in a single-subject type II wrist, utilising cadaveric-validated finite element models.

The type II native wrist model was used to simulate scapholunate interosseous ligament rupture alongside three reconstruction techniques, Modified Brunelli, Corella, and Scapholunate Axis Method, across four distinct wrist motions. Wrist stability was assessed through scapholunate gap and angle, contact area, and multidirectional carpal kinematics.

Scapholunate interosseous ligament rupture caused scaphoid-lunate contact loss, altered carpal rotational mechanics, and increased dorsal/volar scapholunate gaps and angles. The Modified Brunelli Technique demonstrated the closest restoration of normal carpal biomechanics after scapholunate rupture, more effectively restoring scaphoid, lunate, and triquetral rotation, successfully re-establishing scapholunate articular contact, producing a joint contact pattern that more closely resembled the intact joint pattern. Our findings demonstrate that scapholunate interosseous ligament rupture causes less instability in type II wrists than in type I wrists. The additional hamate facet in type II wrists promotes column mechanics and midcarpal stiffness, keeping kinematics closer to the intact state. The superior performance of the Modified Brunelli Technique in the type II wrist stems from its unique graft configuration, which aligns with the wrist's distinct column mechanics.

Following simulation of a scapholunate interosseous ligament rupture in a type II wrist, the Modified Brunelli Technique demonstrated the closest restoration of native kinematics, comparatively to the Corella and Scapholunate Axis Method procedures. The current study provides a platform upon which future work is planned, including evaluating a broader range of wrists to compare surgical techniques and identify optimal approaches for specific wrist types.

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