Introduction There has been an increase in the diagnosis of injuries to the intrinsic ligaments of the wrist due to the more widespread use of arthroscopy in the treatment of patients with musculoskeletal wrist pain, and arthroscopy is particularly very helpful to determine the etiology of these lesions at the ulnar level. The treatment of lunotriquetral ligament injuries encompasses different techniques with results that are little reproducible. Ligament reconstruction through tendon grafting has shown favorable results, but it involves extensive open approaches that lead to a slower recovery a lower range of joint motion due to the excess of scar tissue. The objective of the present study is to describe the performance, in a cadaver, of a minimally-invasive lunotriquetral and secondary-stabilizer ligamentoplasty and its application in a representative clinical case. Material and Methods A preliminary study of six specimens in which a lunotriquetral and secondary-stabilizer ligamentoplasty was performed consecutively through a free tendon graft with arthroscopic assistance. We proceeded to recreate the complete ligament injury, and to perform an assessment of lunotriquetral instability according to the Geissler classification and an arthroscopic ballottement test. We describe the surgical technique, ligament stability after the ligamentoplasty, and the subsequent anatomical dissection, assessing the anatomical structures susceptible to iatrogenic injury. We also describe the application of the technique in one case, comparing the clinical parameters before and after the procedure: range of motion of the joint, strength, pain and the shortened version of the Disabilities of the Arm, Hand, and Shoulder (QuickDASH) questionnaire. Results The ligamentoplasties performed showed recovery of the stability of the lunotriquetral interval assessed according to the Geissler classification and the arthroscopic ballottement test. In the dissection of the specimens, no iatrogenic lesions were found in the tendons or the surfaces of the mediocarpal and radiocarpal joints. The average distances between the nearest bone tunnels and nerves were of 7.3 mm for the sensory branch of the ulnar nerve, of 3.6 mm for the posterior interosseous nerve, and of 4.5 mm for the ulnar neurovascular bundle. No fractures were observed in the tunnelled bones. In the clinical case herein presented, six months after the intervention, there was an improvement in strength and preoperative pain, with a slight decrease in the joint range of motion (15% compared to the contralateral joint). Conclusions The lunotriquetral ligamentoplasty herein described could contribute to the biomechanical restoration of the carpus and be an option for recosntruction in selected cases. Its performance through minimally-invasive techniques, and the use of a free tendon graft together with specific rehabilitation should be considered to optimize the outcomes.