Human Flexor Digitorum Profundus Tendons Research Articles

In vitro effect of transforming growth factor-B1 (TGF-B1) on gene expression in human flexor digitorum profundus tendon cells

Among hand injuries, exor tendon lacerations remain a challenge for hand surgeons. There are presently no therapeutic agents available for the prevention of tendon adhesions. It is already known that TGF-1 plays a role in tendon healing as well as in adhesion formation. Anti-TGF-1 therapies are not eective in preventing adhesion formation. The goal of the present study was to identify possible genes that are aected by TGF-1 in human Flexor Digitorum Profundus (FDP) tendon cells (tenocytes) in vitro. Tenocytes were isolated from human FDP tendons and treated with TGF-1 in low-serum cell culture medium. Gene expression was assessed at 6h and 24h using RTPCR. TGF-1 caused upregulation of several genes (SERPINE1, PLAU, ACTA2, CTGF, FN1, COL1A1, COL3A1, LOX, COMP, MMP13, TIMP1, TIMP3, BGN, SCX, POSTN, SMAD7, IL6, IGF1), downregulation of MMP9, DCN and ACAN, and had no eect on MMP2 and TIMP2. Targeting TGF-1-aected genes may be an alternative therapeutic approach in controlling adhesion formation that may lead to optimal healing of injured FDP tendon or FDP tendon graft.

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

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. 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. There was no significant difference in the peak or normalized peak gliding resistance at any cycle among the 3 groups. Both transverse and oblique trimming of the A2 pulley had similar effects on the peak and normalized gliding resistance after flexor tendon repair. 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.

Comparison of modified Kessler tendon suture at different levels in the human flexor digitorum profundus tendon and porcine flexors and porcine extensors: an experimental biomechanical study

This study compared the biomechanical behaviour of repairs in the human flexor digitorum profundus tendon in zones I, II and III with repairs of different segments of the porcine flexor tendon of the second digit and the extensor digiti quarti proprius tendon, in order to assess the validity of porcine tendons as models for human flexor tendon repairs. These porcine tendons were selected after comparing their size with the human flexor digitorum profundus tendon. The tendon repairs were done in three segments of each porcine tendon and repairs in the human tendons were done in zones I,II and III. Ten tendons in each group yielded a total of 90 specimens. A modified Kessler repair was done with 3-0 coated braided polyester suture and subjected to uniaxial tensile testing. In human flexor tendons, the ultimate force was higher in zones I and II than in zone III. The porcine flexor digitorum profundus tendon from the second digit and the proximal segment of the extensor digiti quarti proprius tendon behaved similarly to the human flexor tendon in zone III and can be considered as surrogates for the human flexor tendon.

Total and Intrasynovial Work of Flexion of Human Cadaver Flexor Digitorum Profundus Tendons After Modified Kessler and MGH Repair Techniques

The purpose of this study was to compare directly the total work of flexion (TWOF) and the intrasynovial work of flexion (IWOF) of human flexor digitorum profundus tendons and to analyze the ratio of the IWOF to the TWOF of human flexor digitorum profundus tendons. These factors may be important clinically in understanding the role of different methods of postoperative tendon rehabilitation for different types of tendon repairs, especially at the early stage after tendon repair. Two different tendon repairs, the modified Kessler and the Massachusetts General Hospital, were used in 18 digits from 6 freshly frozen human cadaver hands. The TWOF and the IWOF were tested by using a digit-resistance testing device. After tendon repair the TWOF increased 11.2% and 26.9% for the modified Kessler and MGH groups, respectively. The differences in increase between the 2 groups were significant. The IWOF increased 126.8% and 308.8% for the modified Kessler and Massachusetts General Hospital groups, respectively. The IWOF accounted for 16.4% of the TWOF for the intact tendon; this percentage was 28.6% and 45.0% for the modified Kessler and Massachusetts General Hospital groups, respectively. The IWOF accounts for 16% of the TWOF of normal human cadaver digits but it accounts for a much higher fraction after tendon repair. The ratio of the work of flexion within the synovial sheath to the TWOF varies depending on the type of repair chosen.

Gliding characteristics and gap formation for locking and grasping tendon repairs: a biomechanical study in a human cadaver model

Purpose The purpose of this study was to compare the frictional characteristics and mechanical properties of various locking and grasping suture techniques in a human in vitro model of flexor tendon repair. Methods Forty-five cadaveric human flexor digitorum profundus tendons were transected in zone II and repaired using 1 of 5 core suture methods (n = 9 per group): either grasping (modified grasping Kessler, modified Lee) or locking (Pennington, modified Pennington, locking Lee) loop suture techniques. All repairs used 4–0 Supramid looped core suture and an epitenon running suture of 6–0 nylon. Gliding resistance at the tendon-pulley interface was measured along with failure strength and gap formation. The force to produce 0.5-, 1.0-, 1.5-, and 2.0-mm gaps were measured. Results One of the locking repairs, the locking Lee, had a gliding resistance significantly higher than that of one of the grasping repairs (modified grasping Kessler) and the other 2 locking repairs (Pennington, modified Pennington) (p < .05). There was no significant difference between the other grasping (modified Kessler, modified Lee) and locking (Pennington, modified Pennington) suture configurations (p = .21). The maximum force of one of the locking repairs, the modified Pennington repair (48.0 N; standard deviation, 3.9) was significantly higher than the other locking and grasping repairs (p < .05). The force required to produce more than 1.5 mm of gap for the modified Pennington repair was also significantly higher than that for some of the other grasping (modified Kessler, modified Lee) and locking (Pennington) repairs (p < .05). Conclusions The lack of significant difference in gliding resistance among the similarly designed modified grasping Kessler, Pennington, and modified Pennington repairs (overall mean, 0.87 N; standard deviation, 0.16) suggests that the locking loop configuration itself does not adversely affect tendon gliding resistance. The modified Pennington repair increased not only ultimate strength but also resistance to gap formation more than 1.5 mm.

Gliding resistance after repair of partially lacerated human flexor digitorum profundus tendon in vitro

Objective. This study reports the gliding resistance between repaired, partially lacerated tendon and pulley in human cadaver digits, using several commonly employed repair techniques. Background. Suture techniques with multi-strands and locking loops have been recommended to reduce the risk of rupture of the repair tendon with early active motion. Such sutures may increase the gliding resistance, and the gliding resistance after tendon repair is also an important factor influencing the rehabilitation. Method. 105 specimens of second, third, or fourth fingers from 36 adult human hands were tested for the gliding resistance between flexor digitorum profundus tendon and A2 pulley in the normal condition. After an 80% laceration, each tendon was repaired with one of the following suture techniques: (1) Kessler; (2) modified Kessler; (3) Savage; (4) Lee; (5) Tsuge; and (6) Becker. All suture techniques were reinforced with a circumferential epitenon simple running suture. After tendon repair, the gliding resistance was remeasured. Results. The gliding resistance of the Becker repair was significantly greater than each of the other four repairs ( P<0.05). The resistance of the modified Kessler repair was significantly less than that of the Kessler, Savage, or Tsuge repairs. Conclusions. We conclude that the type of tendon repair can significantly affect the gliding resistance between the tendon and pulley system after tendon repair. Relevance The design of the tendon repair, through its effect on friction, may have an adverse effect on the clinical results of tendon mobilization.

Biomechanical evaluation of flexor tendon repair techniques.

Immediate active mobilization of repaired tendons is thought to be the most effective way to restore function of injured flexor tendons. Sixty human flexor digitorum profundus tendons were used to evaluate techniques for active tendon motion. The tendons were divided equally into six groups, and each group was assigned to one of the following techniques: Kessler core suture plus running peripheral suture, Kessler plus cross-stitch suture, Kessler plus Halsted suture, Tang core suture plus running peripheral suture, Tang plus cross-stitch suture, or Tang plus Halsted suture. Immediately after tendon repair, an Instron tensile testing machine was used to measure the 2-mm gap formation force, ultimate strength, elastic modulus, and energy to failure of the tendons repaired by these techniques. Ultimate strength, elastic modulus, and energy to failure were measured in load displacement curve. Results showed that the ultimate strength of the Tang plus Halsted or cross-stitch was, respectively, 116.8 +/- 9.6 N and 94.6 +/- 7.8 N; and 2-mm gap formation force was, respectively, 86.6 +/- 4.9 N and 71.9 +/- 5.1 N. The Tang plus Halsted or cross-stitch methods had a statistically significant increase in ultimate strength and 2-mm gap formation force as compared with the Kessler core suture or Tang plus running peripheral suture method. Elastic modulus and energy to failure of the Tang plus Halsted or cross-stitch suture were statistically higher than those of other techniques. The Tang plus cross-stitch or Tang plus Halsted sutures had the highest strength among the tested methods and are appropriate techniques for tendon repair in which the goal is immediate active tendon motion.

Analytic model to predict the strength of tendon repairs.

We developed an analytic model to predict suture load-sharing immediately after flexor tendon repair in the hand. Tendon repair was mathematically modeled as two nonlinear springs in parallel, representing separate core and peripheral sutures that were in series with a third nonlinear spring representing the tendon. To serve as a basis for, and validation of, our analytic model, fresh human flexor digitorum profundus tendons were harvested and mechanically tested either intact or after surgical repair in a variety of ways: core suture alone, superficial peripheral suture alone, deep peripheral suture alone, core suture plus superficial peripheral suture, and core suture plus deep peripheral suture. The stiffness and strength of the composite repairs predicted with use of the analytic model were comparable with those determined experimentally. Furthermore, the model predicted inequities in suture load-sharing, with 64% of the applied load carried by the peripheral suture when it was placed superficially, as compared with 77% when the peripheral suture was placed deep. Our results demonstrate a disparity in load-sharing within composite suture systems, the rectification of which may lead to significant improvement in the repair strength. To this end, we expect that our analytic model will serve as a basis for the design of more efficient, and consequently stronger, suture techniques.

Boundary Lubrication between the Tendon and the Pulley in the Finger*

The lubrication mechanism between the human flexor digitorum profundus tendon and the A2 pulley was investigated in vitro. The gliding resistance at the interface between the tendon and the pulley increased significantly after the tendon had been treated with a hyaluronidase solution. Alcian-blue staining of the surface of the tendon before and after it was treated with hyaluronidase suggested the presence of hyaluronate complex. Alcian blue-positive and hyaluronidase-sensitive materials, such as hyaluronate or proteoglycan, in the synovial membrane and the matrix of the tendon, may act as a boundary lubricant, facilitating the gliding and reducing the resistance between the tendon and the pulley.