It was first proposed in 1981 by Sakellarides et al. that by modifying the original pronator teres radius insertion to the opposite side to act as supination force, it has resulted in an average of 46° supination. However, the significance of such operation has been doubted over time by scholars. Strecker et al. verified that the impact of pronator teres rerouting surgery on supination distinctly excels simple tendon lysis. Nevertheless, the research of Veeger et al. claimed that the effect of pronator teres rerouting restoring supination is equivalent to a tendon lysis. Gschwind and Tonkin carried out their modified approach of a Z-shaped prolongation of pronator teres tendon followed by repairing it bypassing the posterior of radius, pronation strength is thereafter released, good postoperative result is obtained. Although rebuilding of tendon insertion is avoided, due to relatively shorter tendon length, the improper handling of tensile strength can still occasionally affect pronation.[10, 11] The resistance to tensile load of scar-healing prolonged tendon is also comparatively weakened.
Although different operation results have been reported, a number of surgeons still adopt the pronator teres rerouting approach to restore supination, especially when wrist and finger extensions are simultaneously in need of rebuilding while flexor carpi ulnaris muscle or other muscles are selected for use. In most studies above, pronator teres run through interosseous membrane instead of subcutis to avoid adhesion. However, the interosseous membrane plays a key role in a series of ligaments which maintains the stabilization of forearm. Injuring interosseous membrane would affect longitudinal and transverse stabilization of forearm. Incomplete interosseous membrane incision would result in entrapment of pronator teres. Improved supination from simply rerouting pronator teres through interosseous membrane is limited on account of windlass effect, making it ineffective in converting muscle force into supination force. The operating area in such surgery involves more significant deep anatomical structure such as radial artery, radial nerve (above pronator teres), anterior interosseous artery, median nerve and ulnar artery (beneath pronator teres). These structures would get more unrecognizable among scarring soft tissue after primary surgery, increasing operational time and difficulty. Now, these problems can be avoided with our approach.
Pronator teres starts from medial epicondyle of humerus and the medial side coronoid process of ulna, crossing the forearm diagonally and inserting halfway down the lateral surface of the radius. Supinator takes its origin from lateral epicondyle of humerus and lateral side of ulna, ending at the upper volar palmar radius. The origin and termination of these two muscles are at close distance and respectively put radius in spinning motion around ulna in opposite directions. Therefore rerouting pronator teres as supinator is essentially duplicating the mechanism of supinator.
Van Heest et al. meticulously underwent cadaveric studies about restoring of supination through pronator teres rerouting, comparing pronator teres insertions at 6 different positions: volar insertion, interosseous ligament insertion, dorsal insertion, native insertion after rerouting around the radius, volar insertion after rerouting around the radius, and 6 new positions 1cm shifted toward the near end of radius from their original positions. By studying the 12 insertions, the optimum supination is acquired when pronator teres is rerouted through an interosseous window and reinserted into its original insertion place or onto the volar surface of radius. The average active supination angle is at 47°, with no evident disparity of that with 1cm shifts toward proximal radius. This insertion is adopted in our method due to its relatively good supination.
Aderson et al. transfered the tendon of flexor carpi ulnaris to the split tendon of brachioradialis with its bony insertion into the radial styloid. The average supination improvemenet was 37.27 ± 18.21°. Amrani et al. corrected the pronation deformity in 14 children by rerouting the distal part of pronator teres dorsally to volarly through a window in the interosseous membrane and suturing to the proximal tendon. The average supination improvemenet was 73.57 ± 6.33°. Through statistical comparison, we found that average supination improvemenet of our results were significantly better than the former, and there was no significant difference from the latter. However, compared with Amrani’s method, our method avoids damage to the structures between the ulna and radius, reduces the risk of surgery, and simplifies the procedure.