7 Flexor Tendon Repair

10.1055/b-0038-161075

7 Flexor Tendon Repair

Dariush Nikkhah, Wojciech Konczalik

7.1 Flexor Tendon Repair

The case illustrates a patient who grasped a knife with a clenched fist and subsequently has multiple zone 2 flexor tendon divisions (Fig. 7‑1). These injuries can be time consuming to repair and require technical skill and appropriate hand therapy. Single-digit flexor tendon injuries can be repaired under local anesthetic and adrenaline technique, however, in multitendon injury, as in the case above, general anesthetic is supplemented with regional anesthetic and tourniquet.

Fig. 7.1 Multiple flexor zone 2 tendon injuries after grasping a knife with a clenched hand.

Anatomically, these injuries are divided into five zones. Zone 1 injuries occur distal to the flexor digitorum superficialis (FDS) insertion (Fig. 7‑2, Fig. 7‑3). If the flexor digitorum profundus (FDP) tendon becomes detached from the bone, a number of techniques have been described to reattach the tendon to bone. These range from Mitek mini anchor, pullout technique with button, and transosseous repairs (Fig. 7‑4 a–c). Zone 2 has its distal boundary at the FDS insertion and proximal boundary at the distal palmar crease. Zone 2 was known as no man’s land and had poor outcomes historically, until Kleinert popularized direct repair with postoperative rehabilitation exercises. Zone 3 injuries occur in the palm, zone 4 in the carpal tunnel, and zone 5 in the wrist and forearm.

Fig. 7.2 100% division of FDP tendon at zone 1. Note the venting of A4 pulley with preservation of the A3 pulley. There is also evidence of pseudotendon formation.

Fig. 7.3 After repair with a four-strand 3.0 round-bodied Prolene modified Kessler core stitch and 6.0 Prolene continuous epitendinous repair.

Fig. 7.4 Illustration of Mitek mini anchor repair, transosseous repairs, pullout repair with button. **(a)** Button pullout. **(b)** Transosseous repair. **(c)** Mitek mini anchor repair.

In the case illustrated earlier, a midlateral incision was performed to repair the damaged structures in zone 2 (Fig. 7‑5, Fig. 7‑6, Fig. 7‑7, Fig. 7‑8, Fig. 7‑9, Fig. 7‑10, Fig. 7‑11, Fig. 7‑12). Generally, a four-strand modified Kessler repair is performed for the core stitch to minimize the gapping and an epitendinous repair provides an additional 25% strength to the tendon repair (Fig. 7‑13, Fig. 7‑14). At least a 10-mm bite should be taken with the core suture to provide optimal strength. The blood supply to the flexor tendons is dorsal with a relatively avascular volar zone. One should try to preserve the pulleys, mainly the A2 and A4, but, not at the cost of limiting tendon glide. Some surgeons advocate venting to facilitate glide after repair. Indeed, sometimes it is necessary to vent the entire A4 pulley for tendon repair; as long as the A2 pulley is preserved, tendon bowstringing is minimized. Furthermore, in some cases it is not possible to repair both FDS tendons as this will impede FDP excursion, and increase the work of flexion. A dorsal plaster of Paris is used to protect the repair at the end of the procedure (Fig. 7‑15).

Fig. 7.5 To save operative time, all digits are opened through midlateral incisions and flaps are tacked back with silk.

Fig. 7.6 The tenotomy scissors demonstrate Camper’s chiasm. The middle finger has 100% division of the FDS at Camper’s chiasm and the FDP has retracted back proximal to the A2 pulley.

Fig. 7.7 The FDS slips are small, and in this case, these are repaired with a 3.0 round-bodied Prolene suture using a horizontal mattress core stitch. In some cases, it is not possible to repair both FDS slips or the FDP tendon will not be able to glide sufficiently.

Fig. 7.8 A small window is made in the sheath proximal to the A2 pulley and the FDP tendon is retrieved. To pass it under the A2 pulley, a dental wire is used to retrieve the tendon.

Fig. 7.9 Retrieval of retracted FDP with dental wire. A suture is passed twice through the tip of the FDP to make it conical so it can be easily passed through the pulleys. The suture is then passed through the dental wire loop.

Fig. 7.10 **(a,b)** The FDP is retrieved and then anchored with a blue needle.

Fig. 7.11 Repair starts with a back wall 6.0 round-bodied Prolene and then a four-strand 3.0 Prolene round-bodied Kessler repair.

Fig. 7.12 The final repair is tested 10 times to check for gapping at the repair site. In this case, the A3 and A4 pulleys were vented.

Fig. 7.13 Illustration of **(a)** the modified Kessler core stitch and **(b)** a four-strand modified Kessler repair.

Fig. 7.14 Illustration of epitendinous repair.

Fig. 7.15 A plaster of Paris dorsal blocking splint is used to protect the repair in the first 3 days before it is changed to a thermoplastic splint (wrist 0 degree flexion, metacarpophalangeal joint [MCPJ] 40 degrees’ flexion, IPJ straight).

The same principles of tendon repair apply with the flexor pollicis longus (FPL) repair; however, access is best achieved through Bruner-type incisions (Fig. 7‑16, Fig. 7‑17). The FPL can retract to the carpal tunnel and the dental wire technique for retrieval is useful (Fig. 7‑18). Once retrieved, the FPL should be repaired with a four-strand modified Kessler and epitendinous repair with preservation of the oblique pulley to prevent bowstringing (Fig. 7‑19).