To successfully repair a severed flexor tendon, specific biomechanical factors during the rehabilitation period must be considered, as the flexor tenorrhaphy relies on the suture material and its grasp on the tendon for at least the first three weeks, irrespective of the type of repair (Wagner et al, 1994).
A satisfactory repair technique should be biomechanically sound biologically inert user friendly The repair should have a low Iinherent Gapping Potential (IGP), use available suture material and be relatively simple to understand and reproducible in a variety of clinical situations.
We have reviewed the results of the Savage technique and have modified this concept to a more “user friendly” four strand single cross grasp repair with 4-0 or 3-0 braided polyester suture for most flexor tendon repairs. This has been demonstrated to have sufficient tensile strength (median tensile strength: 4 strand 4-0 Ethibond = 45N, 4 strand 3-0 Ethibond = 80N) to allow safe active mobilisation.
The diagram below is for the left hand. Each bite is inserted using the phrase – “in the end and then out to start the first grasp – then go in the direction of the next strand (go the way you are going)on the outside and come back inside the tendon transversely – and then go across the first outside pass (on the outside) to form the single cross grasp and then out the end (inside the tendon)”
“In the end and out to start the grasp, go the way and come back, then across and out the end”.
Then cross the tendon gap ensuring the ends are well opposed, and insert the next bite. The transverse pass of the next grasp must be tensioned as it is generally not possible to take up the slack once a grasp is inserted. Nylon and Prolene will allow tensioning at the end of the repair, but have been shown in our laboratory studies to be inferior to braided polyester in terms of ultimate tensile strength for the same USP rating.
As it is generally not possible to adjust the tension of each strand at the end of the repair, it is critical that the tendon ends remain accurately approximated throughout the repair. This is typically achieved with the standard technique of transfixing hypodermic needles. However this method of tendon stabilisation does not easily permit adjustment of tendon coaptation during the repair and precludes movement of the tendon within the flexor sheath until the needles are removed. A coaptation device (Pactan, Wright Medical Technology) maintains approximation of the tendon ends and allows adjustment during repair.
Pactan Repair Device (www.kaltec.com.au)
As the needles do not transfix the tendon and sheath, the tendon can be advanced or retracted for better access. For most FDP and FPL repairs 3-0 Ethibond or similar is recommended however for smaller tendons, a 4-0 braided polyester suture is sufficient. A 5-0 nylon epitendinous repair is generally performed, but typically only on the palmar aspect of the tendon. The epitendinous suture is used to prevent catching due to irregularity or retraction of the tendon edge and does not contribute significantly to the overall strength of the repair.