ObjectiveTo investigate the effectiveness of modified extensor indicis proprius (EIP) tendon transfer for reconstruction of spontaneously ruptured extensor pollicis longus (EPL) tendon by comparing with the traditional EIP tendon transfer. MethodsBetween January 2009 and December 2011, 11 cases of spontaneously ruptured EPL tendon were treated by modified EIP tendon transfer to reconstruct extension function (modified group). On the base of traditional procedure, the proximal end of EPL tendon was sutured with EIP tendon and the distal end of EIP tendon was crossed round extensor pollicis brevis (EPB) tendon and sutured back with EPL tendon. A specific EI-EPL evaluation method (SEEM) was used to measure the EPL tendon function after transfer. The result was compared with that of the other 18 cases undergoing traditional operation (traditional group). There was no significant difference in gender, age, disease duration, and injury causes between 2 groups (P gt; 0.05). ResultsAll incisions healed by first intention. In traditional group, 5 cases were out of follow-up, and the other 24 cases were followed up 1 year and 6 months on average (range, 8 months-2 years and 6 months). At the last follow-up, according to the evaluation of SEEM, the thumb elevation and flexion deficits of modified group were significantly less than those of traditional group (P lt; 0.05). The independent elevation deficit of the index finger of modified group was similar to that of traditional group (P gt; 0.05). The effectiveness was excellent in 9 cases and good in 2 cases with an excellent and good rate of 100% in modified group, and was excellent in 5 cases, good in 6 cases, and fair in 2 cases with an excellent and good rate of 84.6%. The effectiveness of modified group was significantly better than that of traditional group (χ2=0.03, P=0.03). ConclusionReconstruction of EPL tendon function by modified EIP tendon transfer is effective and easy. It can increase strength of the transferred tendon and obtain satisfactory results, but the long-term effectiveness needs further follow-up.