Background <p>Chronic insertional rupture of the tibialis anterior tendon is uncommon and presents substantial reconstructive challenges, particularly when associated with large tendon defects and distal degeneration. Primary repair is often not feasible in such cases, and conventional reconstructive techniques frequently require prolonged postoperative immobilization, delaying functional recovery.</p> Case presentation <p>We report a case of chronic insertional tibialis anterior tendon rupture in a 64-year-old Japanese male recreational weightlifter, treated with reconstruction using an ipsilateral semitendinosus autograft. A modified side-locking loop suture technique was employed for proximal fixation, and anatomical distal fixation was achieved using multiple all-suture anchors. This construct was designed to provide sufficient initial biomechanical stability to permit early postoperative rehabilitation. Postoperatively, the ankle was immobilized for 2&#xa0;weeks, followed by initiation of active range of motion exercises and progressive weight-bearing. At the 2-year follow-up, the patient demonstrated complete pain relief, normal gait, and excellent functional recovery. Isokinetic testing revealed dorsiflexion strength exceeding 95% of the contralateral side, and magnetic resonance imaging confirmed continuity and favorable remodeling of the reconstructed tendon.</p> Conclusions <p>This case demonstrates that reconstruction of chronic insertional tibialis anterior tendon rupture using a semitendinosus autograft combined with a modified side-locking loop suture and multi-anchor fixation can provide sufficient stability to allow early functional rehabilitation. This approach may represent a viable treatment option for active patients with large tendon defects.</p>