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Page 8 of 25 Bertolini et al. Plast Aesthet Res 2023;10:34 https://dx.doi.org/10.20517/2347-9264.2022.121

RECONSTRUCTION OF EXTENSOR TENDON DEFECTS
The extensor tendons run close to the skin on the dorsal aspect of the hand, lying in a very superficial
position, which makes them particularly prone to injury. Laceration, avulsion and crush are common
trauma dynamics [59,60] .

Whereas simple lacerations could be repaired with direct tendon suture, avulsion and crush injuries may
result in tendon gaps and defects, becoming more challenging to repair [61,62] .

Due to the different degrees of possible excursion of the extensor and flexor tendon systems in hand, the
[63]
tendon defects in the extensors must be managed carefully . Compared to flexor tendons, whose
mobilization, thanks to a moderate excursion degree, can bridge gaps up to 1 centimeter, extensor tendons
[64]
have less excursion, especially in Verdan’s zones from 1 to 5 . Indeed, even a 1-millimeter extensor tendon
elongation in zone 1-5 might lead to a 20° extension lag; on the other hand, even a 1-millimeter extensor
[62]
tendon shortening in zone 1-5 may cause decreased finger flexion .
Primary tendon suture is the optimal surgical technique, but when it is not possible, different surgical
[65]
procedures could be employed, namely tendon lengthening, tendon grafts, and tendon transfers .
The appropriate reconstructive procedure varies according to the injury location, due to the unique
properties of the extensor tendons in each different Verdan’s zone [61,66] . For example, in the wrist and
forearm, extensor tendons are tubular rope-like structures with a morphology comparable to that of flexor
tendons, but going distally, they transform into paper-thin, almost translucent, flat structures .
[63]
Accordingly, the classification of the zones of injury (Verdan’s classification) is of high clinical relevance, as
it permits delineating the subsequent different treatment approaches .
[59]
The purpose of this section is to describe current concepts on extensor tendon reconstruction techniques.

Diagnosis and preoperative evaluation
The assessment of extensor tendon injury is based on the patient's medical history and clinical
evaluation [66,67] . Radiographs are routinely performed in order to detect potential concomitant bone or joint
injury, such as fractures or bony avulsion of the tendon. Second-level imaging is usually not necessary.
Moreover, it is necessary to rule out any concurrent neurovascular damage.

On the physical examination, attention should be paid to any abnormal cascade of fingers and wrist. Elson’s
test helps in the evaluation of the integrity of the central slip . This test is based on the assumption that full
[68]
distal interphalangeal (DIP) extension is not physiologically achievable with the finger flexed at the
proximal interphalangeal (PIP) joint, because of loose lateral bands. Lacerations of the central slip cause the
lateral bands to tighten and migrate towards the pivot axis of the PIP joint while the central slip slightly
retracts. During the examination, the patient’s PIP joint is flexed to 90 degrees. A central slip injury is
evidenced by the patient’s ability to extend or even hyperextend the corresponding DIP joint [68-70] .

If a tendon graft is required during the surgical procedure, the existence of the palmaris longus (PL) should
be checked preoperatively. Patients should oppose their thumb and small finger to test for the presence of
the PL; this structure is absent in 15% to 25% of people .
[71]