CASE                               18                               

A 30-year-old radiographer from your institution was helping to set up a backyard barbeque when a plate broke in her hand, and she sustained a laceration at the base of her left small and ring fingers. She was seen in the Emergency Room. Neurovascular examination was intact. However, the patient had no ability to flex her small finger. A clinical appearance is shown in Figure 4–13.

Figure 4–13

The most likely diagnosis is:

1. Lacerated FDP to the small finger

2. Lacerated FDS to the small finger

3. Lacerations of both FDS and FDP to the small finger

4. Pain inhibition of motion of small finger

Discussion

The correct answer is (C). This patient has no ability to flex either her PIP or the DIP joint. This indicates that neither her FDS nor her FDP is functioning. Given the transverse nature of the laceration across the long axis of the flexor tendons, a clinical diagnosis of FDS and FDP lacerations can be made effectively. In a painful situation, the diagnosis can be made by utilizing local anesthetic to provide pain relief and then asking the patient to flex to confirm presence or absence of flexor function. Conversely, to avoid the patient’s effort and involvement, the simple act of flexion and extension of the wrist may be utilized to provide tenodesis effect and to see if the fingers flex passively when the wrist is extended. This is a reliable sign of confirming intactness of the flexor mechanism.

The patient wishes to return to her occupation as a radiographer at the earliest. The most suitable form of treatment at this point in an effort to allow her to be a radiographer would be which of the following?

1. Placement in a splint in the intrinsic plus position with early active range of motion

2. Open exploration and repair of flexor digitorum profundus tendon

3. Exploration and repair of both the FDS and FDP

4. Excision of flexor digitorum superficialis and repair of profundus tendons only

Discussion

The correct answer is (C). This patient has a wound, which lies over the distal portion of the palm. At this level, given that she has no flexor function, one has to presume that both tendons are injured. However, the injury has occurred in the act of clasping. Therefore, although the injury may be considered to be a zone 3 injury, one has to presume that in the act of clasping, the fingers were flexing, and therefore the flexor tendon injury itself would be more distal and thereby a zone 2 injury. The readers must familiarize themselves with the zones of flexor tendon injury, with zone 2 injuries being the most challenging. Zone 2 injuries consist of injury that occur between the insertion of superficialis at the base of the middle phalanx to the proximal extent of the A1 pulley. This has been referred to traditionally as “no man’s land” and was often thought to be associated with poor outcomes. These outcomes were related to the complexities of flexor digitorum superficialis splitting to allow the profundus to pass through, thereby creating 3 tendons within the flexor sheath at this level. Repair of tendons in this level is often associated with increased bulk and reduced gliding leading to adhesions and poor flexor pull through which then leads to suboptimal outcomes. However, with contemporary techniques, it is possible to perform strong repairs of flexor tendons in zone II and have satisfactory outcomes. In situations where the bulk appears to be inordinately large, it is not uncommon to excise one slip of the FDS to reduce the bulk within the flexor sheath to allow satisfactory function. Repair of both tendons where possible must be performed.

Rehabilitation after such tendon repairs should include which of the following rehabilitation protocols?

1. Unlimited active motion within a few days after surgery

2. Active assisted range of motion within a few days after surgery

3. Passive differential glide motion at DIP and PIP and MP within a few days after surgery

4. No motion for 6 weeks, placement in a short-arm cast

Discussion

The correct answer is (C). Various protocols have been described for flexor tendon rehabilitation after open repair. In the contemporary setting, the most popular and favored means of rehabilitation appears to be that described by Duran and Houser. This protocol relies on passive range of motion of the PIP and the DIP joints as well as the MP joints, which are demonstrated to the patient by a hand therapist. This leads to passive gliding of the repaired flexor tendons within the sheath allowing minimization of adhesions of the flexor tendon to the sheath and also to each other while promoting gliding. This small amount of motion also encourages deposition of collagen fibers along the lines of stress, thereby allowing an early start to an active assisted range of motion program after 3 or 4 weeks of the repair. Other rehabilitation techniques include a dynamic protocol including the use of rubber bands as described by Kleinert as well as early, gently controlled active range of motion.

Objectives: Did you learn...?

Identify the clinical presentation of lacerations of the FDS? Describe various treatment options?

Pinpoint postoperative treatment options?