Tendon Repair Techniques

- Discussion:
    - core suture techniques;
    - strength of flexor tendon repair is proportional to the number of sutures crossing the repair;
    - note that a average force of 20 N required for active digital flexion in humans and most tendon repair techniques need initial
           strength of more than 40 N;
    - modes of failure:
           - gliding resistance:
                  - references:
                         - Gliding and gap formation for locking and grasping tendon repairs: a biomechanical study in a human cadaver model.
                         - Adhesions after flexor tendon repair: a histologic and biomechanical comparison of 2-4-strand repairs in a chickens
           - ultimate tensile strength: (see ultimate tensile strength)
           - gap formation:
                  - is a leading cause of adhesions in immobilized tendon repairs, and therefore suture technique is critical for optimal healing;
                  - in the report by Dinopoulos HT, et al (2000) the authors noted that a 8-strand repair since repetitive loading in vivo may
                            lead to gap formation at lower force levels than those measured during load-to-failure testing; 
                  - if the gap size exceeds a critical size (1-3 mm for the conditions of our study) then the initial advantages of the 8-strand 
                            repair are lost and its mechanical performance is not significantly better than that of the 4-strand repair; 
                  - second implication is that presence of a gap of 3 mm or greater in a repaired tendon indicates that tendon may havebeen
                            loaded past its failure point and can now only sustain a fraction of the force level it could sustain before gapping; 
                  - magnitude of force sustained with a 3-mm gap was only 30 to 40 N for the 2 repair techniques investigated 
                  - tendon with a 3-mm gap is at increased risk of complete rupture compared with a tendon with a gap less than 1 mm;
                  - references:
                         - The resistance of a four- and eight-strand suture technique to gap formation during tensile testing: an experimental study of repaired canine flexor tendons after 10 days of in vivo healing.
                         - The Effect of Suture Preloading on the Force to Failure and Gap Formation After Flexor Tendon Repair  
    - types of suture:
            - traditionally, we have used braided synthetic polyester material (Ethibond), usually of a 3-0 or 4-0 caliber;
            - as noted by Singer MD, et al. (1998), 3-0 Mersilene suture or prolene suture may be suture of choice;
                   - authors note that braided suture may generate more friction and may deform the tendon more than monofilament suture; 
            - PDS may cause excessive inflammation;
                   - Taguchi method for biomechanical comparison of flexor-tendon-repair techniques to allow immediate active flexion.
                   - Effect of absorbable polydioxanone flexor tendon repair and restricted active mobilization in a canine model
                   - Aggressive mobilization following zone II flexor tendon repair using a two-strand heavy-gauge locking loop technique
                   - A Evaluation of Zone II Flexor Tendon Repair Using a Knotless Barbed Suture Versus a Traditional Braided Suture
    - dorsal or volar suture placement:
            - ? whether core sutures should grasp the volar half of the tendon in order to minimize interruption of tendon blood
                      flow (see blood supply);
            - as noted by Soejima, et al (1999), there was superior pull out strength when core sutures were placed in the dorsal half of the
                      tendon (over 50% difference);
            - ref: Comparative mechanical analysis of dorsal versus palmar placement of core suture for flexor tendon repairs.  
    - number of sutures crossing the repair site:
            - classic core suture techniques including the Kessler and the Tajima had only 2 suture arms spanning the repair site;
            - recently it has become clear that the strength of the repair is most related to the number of suture arms crossing the repair;
            - disadvantages of multistrand repairs:
                     - complexity of these repairs which can lead to uneven tendon repair.
                     - increased work of flexion due to operative manipulation and bulk at the repair site;
            - to minimize the risk of tendon re-rupture at the repair site, the surgeon should attempt to place 4-6 sutures across the repair
                     site, in addition to the running epitenon stitch;
            - Dinopoulos HT, et al (2000): that there is high incidence of gap formation at the repair site following tendon repair;
                     - they studied the resistance of a 4- and an 8-strand suture technique to gap formation during tensile testing'
                     - 22 canine flexor tendons were transected, repaired, and tested to failure after 10 days of in vivo healing;
                     - they found that 8-strand repairs sustained 80% higher force at a gap of 1 mm than the 4-strand repairs (average force, 70
                                vs 39 N), but the force sustained at a gap of 3 mm did not differ between groups (35 N for both groups);
                     - they conclude that the 8-strand repair is significantly more resistant to initial gapping during ex vivo tensile testing than
                                4-strand repair but that the two repairs are equally susceptible to rupture if a gap of 3 mm or greater forms; 
            - in report by Boyer MI et al, the authors found that "suture repair technique had a highly significant effect on tensile properties,
                         with tendons in 8-strand group having increased ultimate force (p < 0.001) and rigidity (p = 0.009) and decreased strain
                         at 20 N (p < 0.001) compared w/ tendons in the four-strand group"
                     - refs
                          Intrasynovial flexor tendon repair. study comparing low and high levels of in vivo force during rehab in canines
                          The resistance of a four- and eight-strand suture technique to gap formation during tensile testing: an experimental study of repaired canine flexor tendons after 10 days of in vivo healing.



Biomechanical and clinical evaluation of the epitenon-first technique of flexor tendon repair.

Flexor tendon repair using a "six strand" method of repair and early active mobilisation.

Effect of suture knot location on tensile strength after flexor tendon repair.

Two-, four-, and six-strand zone II flexor tendon repairs: an in situ biomechanical comparison using a cadaver model

Use of the Taguchi method for biomechanical comparison of flexor-tendon-repair techniques to allow immediate active flexion. A new method of analysis and optimization of technique to improve the quality of the repair.

Effect of peripheral suture depth on strength of tendon repairs.    

Biomechanical analysis of four-strand extensor tendon repair techniques

A randomized biomechanical study of zone II human flexor tendon repairs analyzed in an in vitro model

Effect of the cross sectional area of locking loops in flexor tendon repair

The effects of multiple-strand suture methods on the strength and excursion of repaired intrasynovial flexor tendons: a biomechanical study in dogs

Biomechanical properties of four circumferential flexor tendon suture techniques

Core Suture Purchase Affects Strength of Tendon Repairs.

Influence of Core Suture Purchase Length on Strength of Four-Strand Tendon Repairs. 

Biomechanical and clinical evaluation of the epitenon-first technique of flexor tendon repair



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Monday, June 27, 2016 8:35 am