Surgical results and related anatomy research of extensor indicis proprius transfer for reconstruction of thumb extension

XIONG Ge; ZHENG Wei; SUN Yan-kun; ZHANG You-le

doi:10.3969/j.issn.2095-252X.2014.03.011

Abstract：Objective To explore the effects on the functions of the thumb and index ifnger and the related anatomical mechanism of extensor indicis proprius ( EIP ) transfer for reconstruction of thumb extension. Methods A total of 12 patients were retrospectively studied, including 7 males and 5 females, whose mean age was 42.3 years old ( range;18-78 years ). The extensor pollicis longus ( EPL ) was injured in zone III in 4 cases, in zone IV in 5 cases and in zone V for 3 cases. All the patients received EIP transfer for reconstruction of thumb extension. After the operation, the follow-up was carried out through telephone for a mean period of ( 33.5±29.9 ) months ( range;8-83 months ). The functions of the thumb and index ifnger were evaluated. The evaluation indexes of the thumb function were stated as following. ( 1 ) Whether the patient could actively lift the tip of the thumb from the table when the operated hand was placed on the table with the palm down. ( 2 ) Whether the patient could pick the thumb. ( 3 ) Whether the thumb could circle with the first carpometacarpal joint as the pivot when the metacarpophalangeal joint and the interphalangeal joint were maintained unbent. ( 4 ) Whether the interphalangeal joint of the thumb could bend well when the thumb was in the neutral position. The evaluation indexes of the index ifnger function were stated as following. ( 1 ) Whether the patient could actively lift the tip of the index ifnger from the table alone when the operated hand was placed on the table with the palm down. ( 2 ) Whether the patient could extend the index ifnger to the same level of the back of the hand and complete the action of pointing to somebody when the patient clenched the 3rd-5th fingers. ( 3 ) Whether the patient could stilfe an arethusa. ( 4 ) Whether the patient could use the mouse without any dififculty or click the left mouse button twice continuously. In addition, the anatomy research was carried out on 5 adult male cadaver forearm specimens. The original points of the index ifnger and middle ifnger extensor tendons in the extensor digitorum communis ( EDC ) tendons were measured. Results All the patients could use their operated hands for almost all kinds of the daily life and work activities after the operation. Among the young patients, all but one returned to their original jobs. As to the subjective evaluation, 11 patients were satisifed with the surgical results while 1 patient were unsatisifed. Among the 12 patients, 8 patients could fulifll all the 4 pre-designed actions of the thumb, while 3 patients could fulifll 3 actions and 1 patient could fulifll only 2 actions. All the patients can use the mouse without any dififculties. Nine patients could lift the index ifnger from the table when the operated hand was placed on the table with the palm down. All the patients could extend their index ifngers independently, and completed the action of pointing to somebody. Only 7 patients could extend their index ifngers to the same level of the back of the hand with the 3rd and 5th ifngers clenched, while the others could just extend their index ifngers to-20° or-30°. Anatomy research showed that the muscle belly of the index ifnger in the EDC tendon was fairly independent, and the original points of the index ifnger and middle ifnger tendons were quite high. Conclusions EIP transfer for reconstruction of thumb extension can achieve satisfactory results if the indication is proper, with good function of the involved thumb and little functional impairment of the index ifnger. The muscle belly of the index ifnger in the EDC tendons is well differentiated and almost become independent, and the index ifnger can extend independently without the EIP.