[Description of a novel arthroscopic surgical technique for radio-ulnar instability in a cadaveric model]. / Descripción de una nueva técnica artroscópica para la inestabilidad radiocubital distal en modelos de cadáveres humanos.

INTRODUCTION: The distal radioulnar joint is subjected to two resultant loads. Axial load caused by grip and the transversal load due to the possibility of lifting weight against gravity. Therefore, instability of this joint leaves as a consequence a great functional incapacity. For this reason, numerous techniques have been described for its treatment such as Dr. Scheker's technique, a reconstruction technique based on a logical, anatomical, biological, mechanical, and functional solution. METHODS: We performed a descriptive study based in seven cadaveric models and fourteen wrists using a normal minimally invasive arthroscopic technique. The first step of the technique consisted in reproducing instability of the joint by means of a direct lesion of the dorsal fascicle of the triangular fibrocartilage complex. After this procedure, the reconstruction of the distal dorsal radioulnar ligament was carried out with a graft of palmaris longus tendon passed through the drilled tunnels in the distal methaphysis of the radio and ulna. Tunnels were performed under arthroscopic direct vision. The graft was inserted through the tunnels and then, fixed with a 2 mm. Endo-button system and a biodegradable screw of 5 mm. We measured range of motion before and after the surgery. The anterior-posterior translation test was applied on the models to measure instability of distal dorsal radioulnar joint, before, and after the surgical procedure. We performed descriptive statistics with SPPS 10.0 software. RESULTS: The technique was performed in fourteen wrists, with a mean surgical time of 104 minutes (80-164 min). The mean range of motion in flexion was 90.1 degrees before surgery and 90 degrees after surgery. Mean range of motion in extension was 86 degrees before and 88 degrees after the procedure. This finding was significant statistically with a value of p 0.008; the rest of measurements did not reach statistic significance. Stability was achieved in 12 models and 2 had a doubtful anterior-posterior translation test. DISCUSSION: The post-surgery extension was modified by the position and traction of the extremity in the cadaveric models. Two wrists remain unstable, by a technical defect while tensioning the graft at moment of fixation. CONCLUSION: Arthroscopic reconstruction for the distal dorsal radioulnar instability with a tendon graft is a technically reproducible technique. We recovered stability of the joint, and conserved range of motion in a cadaveric study.

[Analysis of histological changes of tendinous grafts in reconstruction of the dorsal wrist ligament]. / Análisis de cambios histológicos de injertos tendinosos para la reconstrucción del ligamento dorsal de la muñeca.

The reconstruction of the dorsal aspect of the triangular fibrocartilage complex in the distal radioulnar joint with an autologous ligament graft has been an optimal treatment for instability of this joint. Tendinous grafts for ligament reconstruction have been studied in ACL reconstruction finding a metaplasia of the tendinous tissue into ligament like tissue. These studies have been performed in humans without making an important lesion to the reconstructed ligament. The purpose of this study is to evaluate the integration and adaptation of a tendon graft into an intraarticular environment with a different mechanical demand. We enrolled 3 patients that underwent reconstruction of the dorsal aspect of the triangular fibrocartilaginous complex in the distal radio ulnar joint, with an evolution between 6 to 48 months, and studied specimens with electronic microscope. In all specimens we found revascularization, reorientation of collagen fibers into a longitudinal pattern at 6 months after surgery, very similar to ligament. Patients did not require further immobilization after biopsy, rehabilitation of range of movement at home, returning to their normal daily activities. We conclude that tendinous grafts for ligamentous instability of distal radioulnar joint undergo histologic changes that make them similar to original ligaments.