Autogenous free sheath grafts in reconstruction of injured digital flexor tendon sheath at the delayed primary stage

Outcomes of repair of the lacerated A2 pulley with extensor retinaculum during primary flexor tendon repair

We report outcomes of repairing the lacerated A2 pulley with extensor retinaculum graft in ten patients (ten fingers) during primary flexor tendon repair in zone 2. Complete A2 pulley lacerations were found in eight fingers and partial A2 pulley laceration in two. We extended the laceration in the sheath to the middle of the A4 or A1 pulley to allow tendon repair with a four-strand core suture. The A2 pulley was reconstructed with an extensor retinaculum graft. All patients followed the early controlled active mobilization protocol and recovered active range of motion at the interphalangeal joints without major extension deficits. Using the Strickland and Glogovac criteria, there were four excellent, five good and one fair result. One finger was graded excellent, eight good, and one fair according to Tang's criteria. No clinical bowstringing was observed. We conclude that extensive pulley lacerations reconstructed with extensor retinaculum primarily ensure functional recovery after tendon repair.

LEVEL OF EVIDENCE

IV.

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.

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.

The effect of seprafilm on adhesion formation and tendon healing after flexor tendon repair in chicken

Adhesion of the tendon, which can occur during healing of tendon repair, is negatively affected by the outcome of surgery. In this experimental study, we sought to prevent adhesion of the tendon, and determined the mechanical stiffness of repair tissue by wrapping sodium hyaluronate and carboxymethylcellulose (Seprafilm; Genzyme, Cambridge, Massachusetts) around the repaired tendon segments. The study group comprised 2 groups of 20 chickens. In group I, the right gastrocnemius tendons of the chickens were cut smoothly, and after tendon and sheath repair, the skin was sutured. In group II, the right gastrocnemius tendons of the chickens were cut, the tendons were repaired, and before skin closure, Seprafilm was wrapped around the repaired tendon segments. Plastic splints were used for holding the chickens' ankles in a neutral position, and they were allowed weight bearing for 8 weeks. In group II, anatomic space between the tendon-sheath and tendon was clear and the tendon-sheath complex was sliding easily around the repaired tendon segment, and this complex was more functional both biomechanically and histologically. Also, the Seprafilm-applied tendons (group II) were observed to be biomechanically more resistant to the tensile forces in group I. Seprafilm is an easily applied interpositional material that can be used safely to prevent adhesion during the tendon healing process.

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.

Biomechanics of the membranous flexor tendon sheath: the role of Grayson's ligaments

BACKGROUND

The biomechanical integrity of the tendon sheath of the fingers has a significant effect on the success of flexor tendon surgery. As nonweightbearing elements, the membranous parts of the sheath have received little attention, and their contribution to sheath movement is still obscure. The authors presumed that Grayson's ligaments, which have been described as force-transmitting elements, might play a role in the biomechanics of the membranous flexor tendon sheath.

METHODS

Twenty-two long fingers of cadaver hands were examined. The authors studied the movements of the inner aspect of the tendon sheath and the positions and patterns of the septa of the palmar soft tissues on picrosirius red-enhanced sagittal and transverse sections and hematoxylin and eosin-stained light microscopy specimens.

RESULTS

The movements of the membranous flexor tendon sheath are controlled by subcutaneous structures. The septal patterns of the palmar fat pads indicate the existence of a highly flexible subcutaneous fibrous system in which the deformable fat pad keeps the force-transmitting elements tight. Collagen bundles in the microscopy specimens, which frequently form layers within the septa, are thought to correspond to Grayson's ligaments. The subcutaneous fibrous system adheres predominantly to the membranous parts of the flexor tendon sheath.

CONCLUSIONS

Folding of the membranous flexor tendon sheath is guided by the subcutaneous fibrous system, of which the macroscopically dissectible elements are Grayson's ligaments. The current surgical approaches might have a deteriorating effect on the biomechanics of the flexor tendon sheath.

Biomechanical and histologic evaluation of tendon sheath management

The effect of changes in diameter of the flexor sheath after tendon repair on tendon function was studied using the long toes of 64 white leghorn chickens. Biomechanical studies of gliding excursion, toe flexion, and ultimate load were carried out at 6 and 12 weeks after tendon repair to determine functions of the tendons healed in narrowed, directly closed, partially excised, and enlarged flexor sheath experimental groups. Histologic examination was used to evaluate the extent of adhesions, healing status of the tendons, and status of the managed sheath. At 6 weeks, gliding excursions and range of toe flexion were statistically the smallest in the group with sheath narrowing, statistically larger in the groups with direct sheath closure or sheath excision, and statistically the largest in the sheath enlargement group (p < .01). These differences in gliding excursions and range of toe flexion were persistently observed at 12 weeks. The ultimate load of the repaired tendons was statistically the weakest in the group with sheath narrowing at either 6 or 12 weeks (p < .01). However, the ultimate load of the groups with sheath enlargement, direct sheath closure, and partial sheath excision was statistically the same. Results of histologic examination demonstrated more severe adhesions and worsened tendon healing in specimens with sheath narrowing. The repaired tendons in the group with sheath enlargement healed better and had less severe peritendinous adhesions than those in the group with sheath narrowing. The extent of adhesions and tendon healing were similar in the groups with sheath enlargement and direct sheath closure. This study demonstrates that the diameter of the repaired sheath exerts significant influence on flexor tendon function. Enlargement of the digital flexor sheath may provide an additional way to improve function of repaired tendons.

Reconstruction of the flexor tendon sheath. An experimental study in rabbits

The role of the tendon sheath in flexor tendon healing was investigated in rabbits. Tendon sheath was reconstructed with syngeneic parietal peritoneum or a non-tanned processed porcine collagen membrane. Resection of the tendon sheath led to adhesions. Reconstruction of the sheath with either graft resulted in a synovial-like lining, resembling a neo-tendon sheath. Even when combined with tendon repair a neo-tendon sheath was seen after reconstruction with both grafts, without adhesions. Subcutaneously implanted processed porcine collagen membrane was completely resorbed in less than 3 months.

The double sheath system and tendon gliding in zone 2C

Anatomical structures, the morphology of gliding tunnel, the gliding amplitude of tendons and the range of finger motion after sheath incision in zone 2C were studied in 40 fingers of ten preserved cadaver hands. The tendon of FDS in zone 2C courses around that of FDP, and FDS serves functionally as a second sheath for FDP. This "double sheath" system in zone 2C accounts for the poor results of tendon repair in zone 2C. The tendon repairs in zone 2C glide into zone 2D during finger flexion. Therefore, the condition of the gliding tunnel of zone 2D is also important to the function of tendon repairs in zone 2C. The range of motion was shown to be insignificantly influenced by partial incision of the A2 pulley, and this did not decrease the total strength of the sheath markedly. These suggest that partial incision or enlargement of the A2 pulley can be carried out for tendon repairs in zone 2C without causing mechanical problems of function.

Flexor tendon repair in zone 2C

A randomized prospective clinical study was carried out in 33 patients (37 fingers) with lacerations of both FDS and FDP tendons in the area covered by the A2 pulley, that is, zone 2C in Tang's subdivision of no man's land. Both lacerated tendons were repaired in 19 fingers and repair of only FDP with regional excision of FDS were performed in 18 fingers. Follow-up of average 12 months revealed that there was no significant difference in the end results evaluated according to the TAM system. The average TAM was 204 degrees in the fingers with suture of FDP only and 187 degrees in those with suture of both tendons. The fingers with suture of both tendons showed a higher rate of re-operation due to adhesions or rupture of repair. This study suggests that it is better to repair only FDP with regional excision of FDS when both tendons are injured in zone 2C.

Dorsal and circumferential sheath reconstructions for flexor sheath defect with concomitant bony injury

Dorsal and circumferential flexor sheaths were reconstructed by autogenous sheath graft in flexor tendon repair in 28 white leghorn chickens. The effect of the sheath reconstructions was evaluated by use of an experimental model of tendon transection associated with bony injury, superficial tendon excision, and 3 weeks of immobilization. Six weeks after reconstruction, the gliding excursion was assessed and adhesion formation, tendon healing, and survival of the grafted sheath were evaluated both macroscopically and histologically. Dorsal and circumferential sheath grafts resulted in tendon gliding that was significantly better than the group with sheath defect not reconstructed. The adhesion formation was apparently less severe, and tendon healing was better in the groups with sheath reconstruction than in the group without reconstruction. The group with dorsal sheath reconstruction did not differ significantly from that with circumferential reconstruction in gliding excursion and adhesion formation. This study demonstrates that separation of the injured tendons from the bony surface by autogenous sheath grafts may be beneficial to tendon gliding and for reducing adhesion formation.