Traumatic flexor digitorum superficialis and A2-A3 pulley rupture: case report

Closed Traumatic A2 Through A4 Pulley Rupture and Flexor Digitorum Superficialis Avulsion Treated With Reconstruction

Background: Multiple closed spontaneous pulley ruptures are rare injuries and require surgical reconstruction to prevent functional deficits. Pulley rupture combined with avulsion of the flexor digitorum superficialis (FDS) tendon is an even more uncommon occurrence.

Case Report: We describe a closed traumatic annular 2 (A2) through annular 4 (A4) pulley rupture with avulsion of the FDS tendon. This uniquely associated pathology was treated with a complex surgical reconstruction that corrected flexion contracture and tendon bowstringing in the left long finger. The desired outcome was achieved through A2 and A4 pulley reconstruction using an autologous palmaris longus tendon graft with FDS tendon excision and proximal interphalangeal joint capsulotomy.

Conclusion: Multiple pulley rupture is not commonly combined with FDS avulsion, and treatment of this injury requires careful surgical planning based on pulley biomechanics to maximize postoperative function.

Sonographical parameters of the finger pulley system in healthy adults

INTRODUCTION

To establish normative values of tendon to bone distances (TBDs) to evaluate the A2 and A4 annular pulley integrity, we hypothesized that these values correlate with gender, athletic exercise, occupation, individual's age and body height.

METHODS

Ultrasonography of 200 healthy individuals was performed prospectively. TBDs for the A2 and A4 pulley sections were measured for all fingers. Evaluation was performed in resting position and active forced flexion. Examination parameters included gender, age, body height, occupation, athletic exercise level, and hand dominance. Assessment of resting position and active forced flexion was done.

RESULTS

No clinically relevant differences of TBDs with respect to the aforementioned parameters were observed. But TBDs were significantly greater in active forced flexion than in resting position for all measured pulley sections. Intraobserver reliability was very satisfactory.

CONCLUSIONS

Establishing normative values will help to detect injured pulleys more precisely and examination should be performed both in resting position and active forced flexion.

Flexor digitorum superficialis repair outside the A2 pulley after zone II laceration: gliding and bowstringing

PURPOSE

To evaluate the changes in maximum flexion angle, gliding coefficient, and bowstringing after a combined repair of both flexor tendons with the flexor digitorum superficialis (FDS) rerouted outside the A2 pulley in cadaveric hands.

METHODS

We performed 4 different repairs on cadaveric hands, with each repair tested on 9 unique digits. In total, 12 cadaveric hands and 36 digits were used. The thumb and little finger were removed from each hand and excluded from testing. Group 1 was sham surgery. Group 2 combined flexor digitorum profundus (FDP) and FDS laceration and repair with both slips of the FDS repaired inside the A2 pulley. Group 3 was FDP repair with one slip of the FDS repaired inside A2 and the other slip left unrepaired. Group 4 was FDP repair with both slips of the FDS rerouted and repaired outside the A2 pulley. Maximum flexion angle, gliding coefficient, and bowstringing were measured in simulated active digital motion for each group.

RESULTS

Rerouting and repairing the FDS outside the A2 pulley (group 4) significantly lowered gliding coefficient compared with repairs with both slips inside A2, with values similar to sham surgery. We observed no significant differences in maximum flexion angle among the 4 groups. Increased bowstringing was observed with both slips of the FDS repaired and rerouted outside the A2 pulley.

CONCLUSIONS

In this cadaveric model, repair of both slips of the FDS outside the A2 pulley improved the gliding coefficient relative to repair within the A2 pulley, which suggests decreased resistance to finger flexion. Repair of the FDS outside the A2 pulley led to a slight increase in bowstringing of the FDS tendon.

CLINICAL RELEVANCE

We describe a technique for managing combined laceration of the FDP and FDS tendons that improves gliding function and merits consideration.