Flexor tendon pulley V–Y Plasty: an Alternative to Pulley Venting or Resection

Comparison of pulley plasty, pulley venting and resection of flexor digitorum superficialis slip after zone II flexor tendon repair: a cadaver study

LEVEL OF EVIDENCE

V.

Secondary Procedures following Flexor Tendon Reconstruction

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Understand the indications and management options for secondary flexor tendon reconstruction, including tenolysis, tendon grafting, and tendon transfers. 2. Understand the reconstructive options for pulley reconstruction. 3. Understand the options for management of isolated flexor digitorum profundus injuries.

SUMMARY

Despite current advances in flexor tendon repair, complications can still occur following surgery. This article presents the spectrum of treatment options for secondary flexor tendon reconstruction ranging from tenolysis to one- and two-stage tendon grafting, and tendon transfers. In addition, an overview of pulley reconstruction and the treatment of isolated flexor digitorum profundus injuries are discussed. A management algorithm for secondary flexor tendon reconstruction is provided.

A4 Pulley Reconstruction Using the Superficialis Oblique Flap and the Transverse Double Loop Techniques: A Biomechanical Evaluation Using a Chicken Model

BACKGROUND

The pulley system plays an important role in flexion mechanism. Reconstruction after trauma can be challenging. Numerous techniques have been described with several drawbacks. Herein, we describe the superficialis flap oblique technique for A4 pulley reconstruction using an animal model.

METHODS

Forty-two fresh legs of 21 eight-week-old chickens were used to evaluate the maximum flexion angle (MFA) and force at maximum flexion (FMF) in intact and sectioned A4 pulley equivalents of the third digit after reconstruction with the transverse double loop (TDL) technique and the superficialis oblique flap (SOF) technique. Biomechanical measurements were obtained in an exclusively designed instrument. Descriptive statistics were reported, and mean differences between the reconstructive techniques were analyzed.

RESULTS

Intact and severed A4 pulley equivalent average MFA were 96.50° ± 1.70° and 115.60° ± 1.50°, respectively. Average FMF were 8.16 ± 0.23 psi with the intact pulley and 6.92 ± 0.20 psi with the sectioned pulley (P < 0.001). After reconstruction with TDL and SOF techniques, the legs reached an average MFA at the distal interphalangeal joint of 98.13° ± 1.20° and 96.90° ± 1.30°, respectively. Mean MFA difference was 1.23° (P = 0.03). Force at maximum flexion was 8.12 psi and 8.10 psi for the TDL and SOF techniques (P = 0.6), respectively.

CONCLUSIONS

The authors believe that SOF technique for A4 pulley reconstruction can be used as first option when available, taking into account its theoretical advantages and its proven biomechanical characteristics. Long-term functional results should be assessed to translate these results into the clinical setting.

Widening of Pulley by Interdigitating Cuts

While biomechanically important, pulleys present multiple challenges to a zone 2 flexor tendon repair and rehabilitation. Retrieval of tendon through an intact pulley is cumbersome. Following repair, venting is often needed to accommodate the bulk at repair site. On occasion, step lengthening, or even complete division of pulley and reconstruction with tendon graft are necessary. Finally, accessing the tendon under the pulley during tenolysis is difficult. The primary issue in all such cases is the lack of space under the pulley. We describe a technique of expanding the pulley by interdigitating cuts. This technique greatly increases the diameter of the pulley which could be demonstrated in cadaver model and noted in clinical setting. This technique is easy to perform and maintains the integrity of the pulley without complete division. It would allow easy tendon retrieval, provide space for the repair and gliding, and improve exposure during tenolysis.

Management of flexor tendon injuries - Part 1: Australian contributions

This review article describes the contribution of Australian authors to the basic science and clinical management of flexor tendon injuries.

Considerations in the surgical use of the flexor sheath and pulley system

The use of the digital flexor sheath to reconstruct damaged structures in the fingers is an intriguing but under-investigated subject. The sheath is anchored firmly to the phalanges and palmar plates and has well-vascularized outer and synovial inner layers. The middle layer is strong and fibrous and not all of it is required for its main biomechanical function of maintaining the moment arm of the flexor tendons. These characteristics have led to several descriptions of different reconstructive uses. In sheath reconstruction, flaps can be used to repair damaged A2 and A4 pulleys. As an anchor, the sheath is useful for tenodeses and tendon transfers. It has been used in the correction of ulnar claw and swan neck deformities. In ligament reconstruction, the A1 pulley has been used to reconstruct the transverse intermetacarpal ligament in cleft hand and ray amputations. The sheath has also been used to cover tendon repairs and periosteal defects with the aim of decreasing adhesions. There is potential for further use of the flexor sheath in reconstructive surgery. The digital flexor sheath can be used to restore various finger functions providing its physiological roles are recognized and preserved. This review considers the different techniques described and their potential uses.

The "turtleneck" pulley plasty for finger flexor tendon repair

Injuries to the flexor tendons are frequent. Even when correctly treated, they can cause a loss of mobility of the digits secondary to postoperative adhesions. Further, conflicts between the tendon suture and the pulleys can limit the range of motion of the tendon and the flexion of the fingers. We propose a new pulley plasty that permits immediate retraining and avoids conflict with the tendon suture. Ten patients underwent surgery for a tendon injury in zone II, with no lesions of the associated pedicles. The tendons were repaired by a 4-strand stitch technique associated with a continuous peritendinous suture. Pulley plasty was systematically performed on A2, A4, or both. Eight patients recovered a satisfactory range of motion with a finger to palm distance of <1 cm, and 2 others with a distance of <2 cm. Two tenolyses were performed, for which no secondary reconstruction of the pulleys was necessary. This plasty technique is simple to carry out, reliable, and reproducible. Because it facilitates tendon repair and reinforces the existing pulleys, it permits immediate retraining and controlled active mobilization.

Flexor pulley reconstruction

Flexor pulley reconstruction is a challenging surgery. Injuries often occur after traumatic lacerations or forceful extension applied to an acutely flexed finger. Surgical treatment is reserved for patients with multiple closed pulley ruptures, persistent pain, or dysfunction after attempted nonoperative management of a single pulley rupture, or during concurrent or staged flexor tendon repair or reconstruction. If the pulley cannot be repaired primarily, pulley reconstruction can be performed using graft woven into remnant pulley rim or looping graft around the phalanx. Regardless of the reconstructive technique, the surgeon should emulate the length, tension, and glide of the native pulley.

Managing the injured tendon: current concepts

Despite advances in understanding of the mechanical aspects of tendon management with improved suture technique and early stress application with postoperative therapy, clinical results remain inconsistent after repair, especially within the synovial regions. Complementary research to enhance the intrinsic pathway of healing, suppress the extrinsic pathway of healing, and manipulate frictional resistance to tendon gliding is now the focus of current basic science research on tendons. In the future, application of these new biologic therapies may increase the "safety zone" (or tolerance for load and excursion without dysfunctional gapping) as therapists apply stress to healing tendons and may alter future rehabilitation protocols by allowing greater angles of motion (and thus tendon excursion), increased external load, and decreased time in protective orthoses (splints). However, at this time, the stronger repair techniques and the application of controlled stress remain the best and most well-supported intervention after tendon injury and repair in the recovery of functional tendon excursion and joint range of motion. The hand therapist's role in this process remains a critical component contributing to satisfactory outcomes.

The effects of oblique or transverse partial excision of the A2 pulley on gliding resistance during cyclic motion following zone II flexor digitorum profundus repair in a cadaveric model

PURPOSE

To compare the gliding resistance of flexor tendons after oblique versus transverse partial excision of the A2 pulley in a human cadaveric model, to determine the effect of the angle of pulley trimming.

METHODS

We obtained 36 human flexor digitorum profundus tendons from the index through the little finger and repaired them with a modified Massachusetts General Hospital suture using 4-0 FiberWire. We repaired all tendons with a similar epitendinous stitch. We randomly assigned the tendons to 1 of 3 groups: intact pulley, transverse partial excision, or oblique partial excision. We measured peak and normalized peak gliding resistance between the repairs and the A2 pulley during 1,000 cycles of simulated motion.

RESULTS

There was no significant difference in the peak or normalized peak gliding resistance at any cycle among the 3 groups.

CONCLUSIONS

Both transverse and oblique trimming of the A2 pulley had similar effects on the peak and normalized gliding resistance after flexor tendon repair.

CLINICAL RELEVANCE

When partial pulley resection is needed after flexor tendon repair, the transverse or oblique trimming of pulley edge does not affect repaired tendon gliding resistance.

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.

The effect of epitendinous suture technique on gliding resistance during cyclic motion after flexor tendon repair: a cadaveric study

PURPOSE

To investigate the effects of motion following repair with a modified Kessler core suture and 5 different epitendinous suture designs on the gliding resistance, breaking strength, 2-mm gap force, and stiffness of flexor digitorum profundus tendons in a human in vitro model.

METHODS

The flexor digitorum profundus tendons of the index, middle, ring, and little fingers of 50 human cadavers were transected and repaired with a 2-strand modified Kessler suture and assigned to 5 groups based on type of epitendinous suture design. The 5 epitendinous designs tested were a simple, running epitendinous suture whose knot was outside the repair (simple running KO); a simple, running epitendinous suture whose knot was inside the repair (simple running KI); a cross-stitch epitendinous suture; an interlocking, horizontal mattress (IHM) epitendinous suture; and a running-locking epitendinous suture. The tendon repair strength and 2-mm gap force were measured after 1,000 cycles of tendon motion. The resistance to gap formation, a measure of repair stiffness, was obtained from the force versus gap data.

RESULTS

None of the repairs showed any gap formation after 1,000 cycles of tendon motion. The cross-stitch epitendinous suture, IHM epitendinous suture, and running-locking epitendinous suture all had significantly lower gliding resistance than the simple running KO epitendinous suture after 1 cycle. The simple running KI epitendinous suture had significantly lower gliding resistance than the simple running KO epitendinous suture after 100 cycles and 1,000 cycles. The differences for gap force at 2 mm and stiffness of the repaired tendon evaluation were not statistically significant. The cross-stitch epitendinous suture, IHM epitendinous suture, and running-locking epitendinous suture all had significantly higher maximal failure strength after 1,000 cycles than the simple running KI epitendinous suture.

CONCLUSIONS

The cross-stitch, IHM, and running-locking epitendinous sutures had the best combination of higher strength and lower gliding resistance in this study. Although these findings suggest a potential for these suture types to be preferred as epitendinous sutures, these repairs should first be investigated in vivo to address their effect on tendon healing and adhesion formation.

Biomechanical comparison of techniques to reduce the bulk of lacerated flexor tendon ends within digital sheaths of the porcine forelimb

PURPOSE

Zone II flexor tendon repairs may create a bulging effect with increased bulk and resistance to tendon gliding. A biomechanical time 0 study was performed to assess 2 methods of tendon antibulking for work of flexion and strength characteristics.

METHODS

We placed 24 fresh-frozen porcine forelimb tendons in a custom jig. Deep flexor tendon was sectioned just distal to the intact A1 and A2 pulleys. Specimens were divided into 3 groups before repair: group 1, nonmodified tendon; group 2, 30 degrees bilateral notch excised from both tendon ends; and group 3, triangular longitudinal central wedge excised from both tendon ends. All repairs used a 4-strand modified Kessler core suture and running circumferential epitendinous suture. Work of flexion, 2-mm gap formation, and ultimate load to failure were tested.

RESULTS

Both antibulking techniques (groups 2 and 3) had significantly less work of flexion than group 1 (36.3 and 34.9 J vs 142.9 J, p < .001). There was no significant change in work of flexion between groups 2 and 3 (p > .05). There was no significant difference in terms of 2-mm gap formation among the 3 groups (p > .05). Groups 1 and 3 exhibited a significantly higher load to failure compared with group 2 (p < .05).

CONCLUSIONS

The antibulking repair techniques used in this study decrease the work of flexion with no significant change in force to 2-mm gap formation. Group 2, however, did have significantly lower load to failure. These techniques might be beneficial in zone II flexor tendon injury, in which the tight annular pulley system restricts tendon gliding. However, this is a time 0 study and the potential adverse effects of increase tendon manipulation and trauma were not analyzed, which might increase adhesions and scar during the healing phase of tendon repair.

A2 pulley incision or one slip of the superficialis improves flexor tendon repairs

Outcomes of flexor tendon repairs in the area covered by major pulleys are often unpredictable. We performed an in vivo study to investigate biomechanical effects of pulley incision, Kapandji pulley plasty, excision of one slip of the flexor digitorum superficialis, or closure of the incised pulley on function of the profundus tendons. Both long toes (104 total) of 52 leghorn chickens were divided into four experimental groups and one control group. The pulley and flexor digitorum superficialis tendon were subjected to the above-mentioned treatments in four groups, with 22 toes per group, after tendon transection in the A2 pulley area. Eight weeks after surgery, incision of the pulley improved excursion of the flexor digitorum profundus tendon and decreased the work of digital flexion over pulley closure. Resection of the one slip of the flexor digitorum superficialis tendon had results similar to pulley incision. Kapandji pulley plasty did not increase tendon excursion and decrease the work compared with a simpler pulley incision. Adhesions were more severe with pulley plasty or closure than with pulley incision. In this avian model, incision of the pulley or partial flexor digitorum superficialis resection improved outcomes of tendon repairs compared with pulley closure. Kapandji pulley plasty did not improve the outcomes over a simple pulley incision.