IntroductionLigament reconstruction and tendon interposition (LRTI) arthroplasty is the procedure of choice of most hand surgeons in the treatment of basal joint arthritis of the thumb. Progressive and natural collapse after trapeziectomy is a common problem. Description of techniqueWe performed LRTI with flexor carpi radialis (FCR) hemitendon technique, then proceeded to block the hemitendon plasty with a bone fragment at the base of the metacarpal. This technique allows us to maintain tension and to obtain immediate stability. Patients and methodsWe conducted a single-center retrospective longitudinal observational study including 51 patients with diagnosis of symptomatic osteoarthritis of the trapeziometacarpal joint. Group A consisted of 24 thumbs treated with trapeziectomy with LRTI with FCR hemitendon using the Burton–Pellegrini technique. Group B included 27 thumbs treated using the modified technique. The postoperative height of the Scaphometacarpal (SM) space was analyzed. Clinical outcome, opposition, retroversion, patient satisfaction and surgical timing were studied. ResultsThe difference of the SM space, after applying correction factor, at one and six months postoperative is significantly less in the modified technique group (P = .033 and P = .001, respectively). The average height loss of the SM space from one to six months postoperative measurement was smaller in the study group, showing greater stability of the plasty. ConclusionsThe use of a bone fragment to block the FCR plasty improves the results at one and six months postoperatively, showing a diminished height loss of the SM space, improved thumb opposition and without prolonging surgical timing in our series.