Comparison of Three Different Internal Brace Augmentation Techniques for Scapholunate Dissociation: A Cadaveric Biomechanical Study

Internal bracing (IB) is an augmentation method using high-strength nonabsorbable tape. However, there is no detailed information about the direction, location, or number of IBs required for scapholunate interosseous ligament (SLIL) injury repair. Thus, this study compared the biomechanical characteristics of short-transverse IB, long-oblique IB, and the combination of short-transverse and long-oblique (Combo) IB for SLIL injury in a biomechanical cadaveric model. We prepared nine fresh-frozen full upper extremity cadaveric specimens for this study. The scapholunate distance, scapholunate angle, and radioscaphoid angle were measured using the MicroScribe digitizing system with the SLIL intact, after scapholunate dissociation and the three different reconstructions. Three-dimensional digital records were obtained in six wrist positions in each experimental condition. Short-transverse IB had a similar effect compared with long-oblique IB in addressing the widening of the scapholunate distance. However, both were less effective than Combo IB. For scaphoid flexion deformity, short-transverse IB had minimal effect, while long-oblique IB had a similar effect compared to Combo IB. Combo IB was the most effective for improving distraction intensity and rotational strength. This study provides important information about the biomechanical characteristics of three different IB methods for SLIL injury and may be useful to clinicians in treating scapholunate dissociation.

Carpal Instability: I. Pathoanatomy

The pathoanatomy of carpal instability is multifactorial and usually complex. A thorough medical history and clinical examination are essential, as well as profound knowledge of the specific instability patterns. The stability of the wrist is ensured by the carpal joint surfaces, by intact intra-articular (particularly the scapholunate interosseous ligament) and intracapsular ligaments, and by crossing extensor and flexor tendons, the latter making the proximal carpal row an “intercalated segment.” An important classification feature is the distinction between dissociative and nondissociative forms of carpal instability. Among others, scapholunate dissociation, lunotriquetral dissociation, midcarpal instability, and ulnar translocation are the most common entities. Early forms of instability are considered dynamic. In the natural course, static instability of the wrist and osteoarthritis will develop. This review focuses on the pathoanatomical fundamentals of the various forms of carpal instability.

Difference in Carpal Alignment between Scapholunate Dissociation and Kienbock Disease: A Retrospective Study

Introduction Scapholunate dissociation is the most frequent type of wrist instability and, if untreated, can lead to wrist osteoarthritis, known as scapholunate advanced collapse. Kienbock disease can also lead to wrist osteoarthritis. Both involve carpal instability; however, the possibility of completely different mechanisms underlying each ligamentous state and carpal malalignment must be considered. Materials and Methods We retrospectively reviewed 17 patients with scapholunate dissociation and 14 patients with Kienbock disease. All arthroscopic findings for scapholunate dissociation were classified as Geissler grade 4. All cases of Kienbock disease were treated by lunate resection and vascularized pisiform transfer without interosseous ligament reconstruction. Carpal alignments were evaluated from pre- and postoperative radiographs. Results Scapholunate dissociation showed greater lunate dorsiflexion and more dorsal locations of the scaphoid and capitate compared with Kienbock disease, but preoperative scaphoid flexion was similar in both groups. Eleven of 17 cases of scapholunate dissociation and no cases of Kienbock disease showed dorsal subluxation of the scaphoid preoperatively. Postoperative radiographs revealed no progression of carpal collapse in either groups. Conclusion This study revealed the sacrifice of the scapholunate/lunotriquetral interosseous ligament do not incur static scapholunate dissociation, and that the secondary stabilizers may preserve carpal alignment.

Intercarpal ligamentoplasty for scapholunate dissociation: comparison of two techniques

We modified our original surgical technique of scapholunate intercarpal ligamentoplasty for treating chronic scapholunate dissociation. The aim of this study was to compare the outcomes in patients treated by the same surgical team with the original method and the modified method over two different time periods. Nineteen patients with a mean age of 40 years were treated with the original method (mean follow-up of 34 months, range 12–54), and 21 patients with a mean age of 38 years were treated with the modified method (mean follow-up of 27 months, range 13–40). In both groups, we found a significant improvement in pain levels, grip strength, functional scores in terms of QuickDASH and Patient-Rated Wrist Evaluation, and radiographic scapholunate gap and scapholunate angle after surgery. There were no significant differences between the two groups in outcome measures except the scapholunate gap, which was significantly better controlled by the modified procedure. Between the immediate postoperative period and the last follow-up, there was a significant increase in the scapholunate gap and scapholunate angle after the original method, while there only a small increase after the modified method. We conclude that both versions of the scapholunate intercarpal ligamentoplasty yield satisfactory clinical and radiological results in the short to mid-term. The modified method makes the triquetral surgical step easier and seems to better optimize the tension across the ligamentoplasty, thus maintaining the intercarpal correction. Level of evidence: III