Purpose The primary treatment goals for advanced-stage thumb carpometacarpal (CMC) joint osteoarthritis are complete pain relief and restoration of thumb strength. The purpose of the present study was to introduce a variation of the abductor pollicis longus (APL) suspension arthroplasty using a single looping of a radial slip from the APL tendon around the flexor carpi radialis (FCR) tendon combined with RegJoint™ interposition and to determine its efficacy in the treatment of thumb CMC joint osteoarthritis. Methods Between 2015 and 2017, 21 patients were included. The average age was 60.8 years (range 48–79). The mean follow-up was 27.7 months (range 8–50). Evaluation included pain, radial and palmar abduction, tip pinch and grip strength, and Disabilities of the Arm, Shoulder, and Hand (DASH) score. Results Pain averaged 0.3 (range 0–4) at rest and 1.4 (range 0–4) on exertion. The radial and palmar abduction were 97% and 99% compared to the contralateral side. The tip pinch and grip strength were 4.1 kg (range 3–6.5) and 22 kg (range 13.3–40), respectively. The DASH score accounted for 18.5 (range 0.8–41.7). Conclusion The modified APL suspension interposition arthroplasty was an efficient and simplified option for the treatment of thumb CMC joint osteoarthritis, with results comparable or better than other published procedures. The APL suspension technique was easy to perform avoiding difficult bone tunneling and incision of the FCR tendon. The RegJoint™ interposition as spacer prevented impingement of the first metacarpal base on the second metacarpal base or the trapezoid bone.