Acute zone I flexor tendon injuries are a commonly encountered condition caused by either an avulsion of the flexor digitorum profundus (FDP) tendon from its insertion on the distal phalanx of the finger (the so-called jersey finger) or a laceration of the FDP tendon distal to the insertion of the flexor digitorum superficialis (FDS) tendon. A frequently used classification system for these types of injuries was introduced by Leddy and Packer (1) in 1977 with a modification added by Trumble et al. (2) in 1992. This classification system aids the surgeon in choosing timing of and appropriate treatment for these injuries. Type I injuries occur when the FDP tendon avulses and retracts into the palm, thus disrupting the entire blood supply and nutritional support of the tendon. The viability of the tendon is jeopardized, and repair must occur within 7 to 10 days of injury. Type II injuries occur when the tendon retracts to the level of the proximal interphalangeal (PIP) joint, which likely signifies some remaining blood supply via the long vinculum and diffusion of nutrients through the synovial fluid. Delayed repair up to 6 weeks postinjury can be attempted with success (however, the goal should be repair as soon as possible). Type III injuries occur when the tendon only retracts to the level of the A4 pulley typically because the FDP tendon avulses a piece of bone, which prevents further retraction. Both vinculae remain intact and tendon viability is preserved affording delayed repair. Type IV injuries occur when the FDP tendon detaches and retracts from the bony avulsion fragment and viability of the tendon is unpredictable. Differentiating between type III and IV injuries can be challenging, and when physical exam findings are inconclusive, further imaging may be required. While all of these injuries occur outside of the proverbial “no man’s land,” they still pose significant challenges, which include localizing the tendon and passing it through the annular pulleys of the retinacular sheath, achieving robust healing between tendon and bone, as well as avoiding the “quadrigia” effect, which can occur when the tendon is shortened greater than 1 cm. This shortening places increased tension on the remaining tendons of the FDP muscle with resultant diminished flexion of the remaining digits or “quadrigia.” We will limit our discussion in this chapter to the repair of acute zone I tendon injuries.

Patients classically present with a history of a forced extension injury to an actively flexed digit or a laceration sustained to the volar surface of the digit distal to the insertion of FDS. On physical exam, the normal cascade of the fingers will be disrupted with the affected finger held in a more extended posture. The patient will be unable to actively flex the distal interphalangeal (DIP) joint, most easily tested by holding the metacarpophalangeal (MCP) and PIP joints of the digit in full extension. Sometimes, an avulsed bony fragment may be palpated along the digit. A thorough examination of the entire hand and forearm should be performed to identify any other concomitant injuries. The point of maximum tenderness along the injured digit or proximally in the palm is often an indication of where the proximal avulsed tendon end resides. Radiographs may demonstrate the location of an avulsed bony fragment or any other bony injury. When the diagnosis remains elusive, ultrasound
(US) or magnetic resonance imaging (MRI) may be appropriate. These additional imaging modalities can also aid in identifying the location of the proximal FDP tendon stump, which in a delayed presentation may alter the treatment course.

The restoration of function to a digit that has sustained a flexor tendon injury can be a long and tedious road. Considerable time should be devoted to counseling the patient regarding the nature of the injury as well as the possible need for secondary operations and the extensive postoperative rehabilitation required to achieve a desirable outcome.

As stated above, a thorough physical examination will most oftentimes determine the extent of injury. The surgeon must note the normal resting finger cascade, location, and extent of any wounds; document individual tendon function of the FDS and FDP; and assess digital nerve function and vascular integrity of the digit. We also carefully palpate along the flexor sheath and palm evaluating for the point of maximum tenderness. This point most often corresponds with the location of the retracted tendon end. Radiographic examination of digit and hand evaluates for avulsion fractures of distal phalanx volar rim and associated bony injuries. More advanced imaging (MRI/US) is utilized at the surgeon’s discretion and is individualized by each case and unique presentation.

Either regional or general anesthesia is utilized per surgeon and anesthesiologist choice. Wide awake surgery is gaining popularity for these injuries but has yet to be utilized at our institution and is discussed in detail elsewhere in this book. The patient is placed supine on the operating table with the arm abducted 90 degrees at the shoulder and a well-padded tourniquet is applied. Preoperative antibiotics are administered within 1 hour of skin incision. The surgical “time-out” is completed. The “time-out” is an opportunity to confirm that all special equipment is available including tendon graspers, pediatric feeding tube, handheld power/wire driver, micro instruments, and fracture fixation set when indicated and sheath dilator (we routinely use the Toby Orthopaedic disposable device). The suture of choice is individualized, but we prefer for an end-to-end repair to use 4-0 looped Supramid Extra LCW on a 3/8 inch taper needle or 4-0 Ethibond suture on an RB1 taper needle. For a tendon to bone repair, we use a 3-0 Ethibond suture and two Keith needles. Alternatively, micro-sized suture anchors of choice may be utilized. The arm is exsanguinated, and the tourniquet is inflated to 100 mm Hg above the patient’s systolic blood pressure. The surgical approach can vary between a Brunner style and midaxial incision along the digit with extension proximally into the palm as needed. Generally, we prefer an oblique incision over the distal phalanx with a midaxial extension toward the MP flexion crease if a proximal extension is anticipated (Fig. 14-1

Stay updated, free articles. Join our Telegram channel

Join