Gliding resistance and triggering after venting or A2 pulley enlargement: a study of intact and repaired flexor tendons in a cadaveric model.

PURPOSE: This study compared the effect of 2 techniques of pulley management--venting and pulley enlargement (complete A2 incision with pulley repair and sheath closure using a retinacular graft)--on gliding resistance and on the incidence of triggering following zone 2 flexor tendon repairs in human cadaver specimens. METHODS: In vitro gliding resistance and the incidence of triggering were determined in 10 human cadaver specimens under 5 progressive conditions: (1) intact, (2) tendon repair (both tendons cut and repaired with the sheath intact), (3) condition 2 plus 50% venting of the distal A2 pulley, (4) condition 2 with venting extended to 66% of distal A2, and (5) condition 4 plus pulley enlargement. Triggering was determined in the same specimens by 2 computational algorithms that detected force changes in the load cells used to measure gliding resistance. RESULTS: Tendon repair increased gliding resistance from the intact condition by an average of 229%. Gliding resistance was reduced in conditions 3, 4, and 5 from the repair condition by 15%, 25%, and 22%, respectively. Triggering commenced with tendon repair in some specimens, and its incidence increased with 50% venting. Further venting reduced triggering, but not as effectively as pulley enlargement did. CONCLUSIONS: In this cadaveric study, venting and pulley enlargement reduce gliding resistance by equivalent amounts. Triggering persisted despite venting. The surgeon should carefully examine tendon repairs for free gliding. Pulley enlargement might be more effective than venting in reducing the incidence of triggering.

Primary pulley enlargement in zone 2 by incision and repair with an extensor retinaculum graft.

PURPOSE: This retrospective study documents the results of primary enlargement of tendon sheath pulleys by incision and extensor retinaculum graft repair during flexor tendon repairs in zone 2 in 9 fingers. METHODS: The entire A2 or A4 pulley was enlarged by complete incision and repaired with an interposed extensor retinaculum graft at the time of primary flexor tendon repair in a total of 9 fingers in 7 patients, ages 15 to 54 years. The indication for primary pulley enlargement was failure of the tendon repair to glide smoothly and without snagging through the normally tight-fitting pulley system. In no case was more than one major pulley enlarged, and the entire A1 pulley was never enlarged. The zone 2 tendon repairs were done using a 2-strand modified Kessler 3-0 core suture and a 6-0 nylon running circumferential suture. The follow-up averaged 3.6 years. Interphalangeal total active motion and Strickland-Glogovac grade in patients with adequate follow-up of more than 6 months or obtaining full range of motion were obtained from a retrospective chart review. RESULTS: Interphalangeal total active motion averaged 127 degrees and the scores according to the Strickland-Glogovac system were excellent for 3, good for 2, fair for 2, and poor for 2. There were no tendon ruptures. Two fingers in one patient required a tenolysis and a third finger had secondary skin scar lengthening. Two fingers had visible and palpable bowstringing when seen at long-term follow-up and there was an average flexion contracture of 21 degrees. CONCLUSIONS: Primary pulley enlargement using a free graft in zone 2 tendon injuries may achieve the 3 goals of providing a good gliding environment, avoiding triggering, and minimizing bowstringing. These initial clinical outcomes are average for zone 2 tendon repair, but encouraging. Further research and refinement in surgical technique and rehabilitation method are needed to minimize flexion contractures.

Primary tendon sheath enlargement and reconstruction in zone 2: an in vitro biomechanical study on tendon gliding resistance.

PURPOSE: To investigate our hypothesis that primary pulley enlargement and repair using an extensor retinaculum graft will reduce tendon repair gliding resistance. The benefit of pulley enlargement has been tested in experimental animals, but its effect on gliding resistance in vitro using human fingers is not known. METHODS: In vitro gliding resistance in the proximal tendon sheaths (A1 through A3) was measured and compared in 7 cadaver fingers using the method of Uchiyama and colleagues at a fixed 50 degrees over the proximal sheath under 3 conditions: (1) intact tendons with intact proximal sheath; (2) laceration and 2-strand core plus running epitenon repair of the tendons with intact sheath; and (3) repaired tendons with enlargement of the A2 pulley and adjacent proximal sheath by incision and repair with an extensor retinacular graft. Results were analyzed statistically. RESULTS: Gliding resistance increased from an average of 0.44 N +/- 0.07 in the intact condition to an average of 1.51 N +/- 0.23 (a mean increase of 243%) when the tendons were cut and repaired. Enlarging the proximal sheath by sheath incision and graft repair reduced the gliding resistance from the repair condition to 1.04 N +/- 0.15 (a mean decrease of 31%). These changes are statistically significant. CONCLUSIONS: In vitro, repaired tendons had a greater resistance to gliding than that of the intact tendons through the proximal sheath when tested by the method of Uchiyama and colleagues. Enlargement and repair with an extensor retinacular graft of the A2 pulley and adjacent sheath significantly reduced resistance to repaired tendon gliding. These findings support further investigation into the concept that primary pulley enlargement may improve tendon function after repair.

Anatomic factors related to the cause of tennis elbow.

BACKGROUND: The pathogenesis of lateral epicondylitis remains unclear. Our purpose was to study the anatomy of the lateral aspect of the elbow under static and dynamic conditions in order to identify bone-to-tendon and tendon-to-tendon contact or rubbing that might cause abrasion of the tissues. METHODS: Eighty-five cadaveric elbows were examined to determine details related to the bone structure and musculotendinous origins. We identified the relative positions of the musculotendinous units and the underlying bone when the elbow was in different degrees of flexion. We also recorded the contact between the extensor carpi radialis brevis and the lateral edge of the capitellum as elbow motion occurred, and we sought to identify the areas of the capitellum and extensor carpi radialis brevis where contact occurs. RESULTS: The average site of origin of the extensor carpi radialis brevis on the humerus lay slightly medial and superior to the outer edge of the capitellum. As the elbow was extended, the undersurface of the extensor carpi radialis brevis rubbed against the lateral edge of the capitellum while the extensor carpi radialis longus compressed the brevis against the underlying bone. CONCLUSIONS: The extensor carpi radialis brevis tendon has a unique anatomic location that makes its undersurface vulnerable to contact and abrasion against the lateral edge of the capitellum during elbow motion.

Pronator teres rerouting in children with cerebral palsy.

PURPOSE: The forearm in children with cerebral palsy often assumes uncontrolled dynamic positioning in pronation when the hand is put into use. This hypertonic positioning seems to be an expression of dystonia rather than spasticity. This article reports the effect of pronator teres rerouting (PTR) using the technique of tendon Z-lengthening and repair on active motion and on forearm positioning during use. METHODS: Thirty-one patients who had pronator teres rerouting were observed before and after surgery for active and passive forearm range of motion, changes in dynamic forearm positioning, and the performance of 5 functional tasks related to forearm rotation. The primary indication for surgery was pronation positioning of 25 degrees or greater because that positioning precludes grasping a glass or cup of water. RESULTS: The follow-up period averaged 39 months. The average active supination increased 65 degrees, and the average dynamic positioning changed from 26 degrees pronation to 7 degrees pronation. Thirty of the 31 patients gained the ability to hold a cup of water in the involved hand. Nine children positioned the hand in supination during grasp. CONCLUSIONS: Pronator teres rerouting improves both active supination and dynamic forearm positioning in children with cerebral palsy. The use of the technique described in the literature resulted in slight overcorrection of forearm positioning in the nine children. This finding is consistent with the concept that positioning disorders are at least partly dystonic rather than spastic. It is recommended that the transfer be tensioned more loosely in children who have excessive dynamic hypertonia. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level IV.