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 managementventing 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. Clinical relevance: This basic science, biomechanical study is intended to improve understanding of zone 2 tendon repair behavior, including gliding resistance and triggering, thereby improving flexor tendon repair results.