Management of Complications in the Treatment of Fingertip Injuries

21 Management of Complications in the Treatment of Fingertip Injuries

Florian S. Frueh and Maurizio Calcagni

Abstract

The fingertip is the most frequently injured part of the hand. Accordingly, complications after fingertip injuries are very common and knowledge about their treatment is important for hand surgeons. Nail deformities, such as nail ridges, split nails, or hook nails can be challenging to correct. While nail ridges are relatively easy to address, split nails and hook nails are difficult problems and may also be solved with nail eradication and skin grafting. Painful neuromata are another common and potentially debilitating complication of fingertip injuries. Traditionally, the surgical treatment includes resection of the neuroma with nerve shortening and relocation. However, a multitude of treatment strategies has been described without a single technique providing superior results. Finally, tendon or bone infection, cold intolerance, and hypotrophic digital pulps may occur after fingertip injuries. While exarticulation and finger shortening can always be performed, specific and more sophisticated surgical procedures should be part of the armamentarium of hand surgeons to maintain digital length and function.

Keywords: cold intolerance, fingertip injuries, hypotrophic fingertip, infection, nail deformity, neuroma

21.1 Introduction

The fingertip is defined as the part of a finger distal to the insertion of the extensor and flexor tendons on the terminal phalanx.1 With a unique anatomy, it is essential for highly specialized functions such as sensation, protection, or fine manipulation. Due to its high mechanical exposure during hand use, it is the most commonly injured part of the hand.² Hence, managing fingertip injuries and their complications is among the most frequent problems encountered by hand surgeons. Injuries to the fingertip can be classified according to their etiology (i.e., Guillotine vs. crush vs. crush avulsion injury³) or according to the extent of tissue loss. For that purpose, the fingertip has been divided into different zones (Fig. 21‑1).⁴^,⁵ While very distal fingertip injuries commonly undergo uneventful healing by secondary intention, more proximal injuries with significant bone and nail bed loss (i.e., >Hirase IIA and Allen II type amputations) exhibit a higher risk for complications. In order to prevent potentially severe sequelae, each anatomical component of an injured fingertip should be addressed meticulously during the primary treatment. In the present chapter, we discuss the most important complications after fingertip injuries and their surgical management.

Fig. 21.1 Classification of fingertip amputations according to Hirase and Allen. Hirase classification: I = distal to digital artery termination, IIA = distal to terminal division of central artery, IIB = distal to nail fold, type III = distal to DIP joint. Allen classification: I = distal to nail bed, II = distal to terminal phalanx, III distal to lunula, IV = distal to DIP joint.

21.2 Nail Deformities

Except for very distal injuries involving only the pulp, the nail bed is always affected in fingertip injuries. Nail bed lacerations can be open and obvious (i.e., lacerations or amputations) or closed and more challenging to recognize, for example, when associated with crush injuries and fractures of the terminal phalanx. Nail deformities after fingertip injuries are very common and highly disturbing for patients due to a frequently eye-catching aesthetic abnormality. Moreover, fragile nail plates with sharp edges may result in significant functional impairment. From a morphological point of view, three different types of nail deformities can be found: nail ridges, split nails and hook nails.⁶ Nail ridges occur after missed or uneven repairs of the nail bed or following dorsally displaced fractures of the subungual bone. Split nails, in contrast, are found after scarring of the germinative matrix. Finally, hook nails occur following insufficient volar bony support, for instance, in oblique fingertip amputations. If the nail bed is not trimmed back meticulously, the lack of bone support results in a volarly curved nail growth with aesthetical and functional impairment.

21.3 Painful Neuroma

The formation of a painful terminal neuroma is a common complication of fingertip injuries. Many cases can be managed conservatively by means of desensitization exercises and the temporary use of protection devices instructed by a trained hand therapist. However, if severe neuropathic pain develops, surgical treatment may be indicated. The clinical presentation of painful terminal neuromas of the digital nerves is predominantly characterized by pressure pain and hypersensitivity.⁷ The diagnostic algorithm includes a digital block with a local anesthetic, after which the patient should be pain-free or experience significant pain relief. In case of persistent pain after nerve block and when abnormal local trophism is present, the surgeon should think of a complex regional pain syndrome type II as differential diagnosis.

Frequently, the surgical treatment of painful digital neuromas is delayed, and the function of the affected digit and hand is markedly limited with often significant socioeconomic consequences, in particular for blue-collar patients. Time is an important factor when treating patients with highly symptomatic neuromas. Hence, we recommend early and aggressive surgical treatment of debilitating digital neuromas. A multitude of methods for the surgical management of digital neuromas has been described, including shortening and nerve relocation in bone or muscle, end-to-side neurorrhaphies, nerve capping, local flaps or—more recently—the use of regenerative peripheral nerve interfaces (RPNI).6^,⁷^,⁸^,⁹ However, none of these techniques is accepted as gold standard and outcomes of revision surgery are difficult to predict. In our experience, patients with debilitating and chronic neuropathic pain are at highest risk for permanent symptoms even with revision surgery. Hence, this point should be clarified when the consent for surgery is obtained from the patient because unrealistic expectations may jeopardize the compliance during the early and critical phase of recovery, where hand therapy should be attended with maximal discipline.

21.4 Infection

Severe infections after fingertip injuries are rare. However, destructive osteomyelitis of the terminal phalanx or pyogenic flexor tendon synovitis can occur with potentially fatal consequences for the function of a hand. Osteomyelitis after contaminated open injury is often polymicrobial and requires a combined treatment including surgery and antibiotic therapy.¹⁰^,¹¹ The diagnostic algorithm includes X-ray images of the affected finger and bone biopsies with detection of characteristic pathology and positive cultures.

21.5 Cold Intolerance and Fingertip Hypotrophy

Cold intolerance and significant hypotrophy of the digital pulp are common complications of fingertip injuries. In the pertinent literature, rates from 30 to 100% have been reported for cold intolerance.¹²^,¹³ According to our experience, these problems are more often found after the conservative treatment of proximal fingertip amputations using occlusive dressings. Hypotrophic fingertips are a particularly disturbing problem because patients suffer from limited mechanical robustness of a single finger in an otherwise normal hand. Cold intolerance is difficult to treat and commonly ameliorates over time and with support of a hand therapist. In contrast, hypotrophic fingertips commonly profit from soft tissue augmentation with local flaps or—usually less effective—injection of autologous microfat.

21.6 Authors’ Own Experience and Preferred Technique

21.6.1 Nail Deformities

Nail ridges can be managed straightforward with nail plate removal and resection/reconstruction of uneven nail bed areas. Larger nail bed defects can be reconstructed using acellular dermal matrices or nail bed transplants harvested from the toes. In contrast, the surgical management of split nails is more challenging. Depending on the size of the destructed matrix area, the scar can be resected with direct repair in small defects. If the matrix defect is extensive, reconstruction is difficult and ablative procedures such as nail eradication with subsequent full-thickness skin grafting may be more suitable. Finally, hook nails can be corrected in selected cases, but the patients should be informed about considerable surgical investment with the risk of recurrent nail deformity. Hook nails can be corrected with restoration of bone support, such as bone transplantation in combination with local flaps. However, many patients prefer a faster solution with nail ablation. Taken together, nail deformities should be avoided by a thorough primary assessment and treatment with anatomical reconstruction of the damaged nail structures.

21.6.2 Painful Neuroma

Prevention is key: To minimize the risk of symptomatic terminal neuroma formation after fingertip injuries, we recommend aggressive shortening of lacerated digital nerves with sufficient soft tissue coverage during the primary treatment. Furthermore, the nerve stump can be infiltrated with a local anesthetic and sealed with bipolar cautery. Our standard surgical approach to painful digital neuromata of the fingertip includes neuroma resection with nerve shortening and proximal relocation. Notably, we have made convincing first experiences with RPNI for the treatment of larger nerve neuromas, but this novel technique will have to be tested in randomized clinical studies before a broader application can be suggested.

21.6.3 Infection

Pyogenic flexor tendon synovitis is commonly treated with aggressive surgical debridement, including rinsing of the flexor tendon sheath and intravenous antibiotics. Selected cases such as early stage infection without sonographic evidence of peritendinous pyogenic collections can be managed conservatively with intravenous antibiotics alone.14 However, these cases should be monitored closely by a hand surgeon to verify clinical improvement within reasonable time (i.e., within 24–48 h).

Osteomyelitis of the terminal phalanx can be managed with exarticulation of the distal interphalangeal joint. If digital reconstruction is feasible, aggressive debridement of the affected bone with subsequent bone transplantation and adequate soft tissue reconstruction should be performed. For this purpose, the distal radius or the iliac crest are suitable donor sites. Key to a good result is a solid soft tissue coverage after bone transplantation. In our hands, local neurovascular island flaps, such as Venkataswami or dorsal finger perforator flaps,¹⁵ are reliable work horses for the reconstruction of insufficiently covered fingertips.

21.6.4 Fingertip Hypotrophy

Insufficient soft tissue of the digital pulp following conservative treatment of fingertip injuries may lead to pain while pinching and is particularly disturbing for patients who are dependent on precision work, such as musicians. Commonly, the terminal phalanx is only covered with a thin layer of scarred dermis and epidermis without a subcutaneous layer, which is critical for shock absorption during pinching (Fig. 21‑2a–d). The reconstruction of hypotrophic fingertips can be achieved with local neurovascular island flaps, such as VY advancement (Fig. 21‑2e–h) or Venkataswami flaps with reliable results. In addition, a frequently present and aesthetically disturbing short nail can be improved using an eponychial flap¹⁶ (Fig. 21‑2i, j). From a technical point of view, this flap is simple and only results in ~10 min of additional operating time. Full loading of the reconstructed pulp is allowed after ~4 weeks (Fig. 21‑2k, l).

Fig. 21.2 Surgical correction of a hypotrophic fingertip. (a–c) Preoperative findings with insufficient coverage of the terminal phalanx. (d) Normal fingertip. Scale bars: c = 1 mm; d = 3 mm. (e–h) Design and dissection of an extended neurovascular VY flap (f, arrowhead) with appropriate advancement (g, arrowhead). (i,j) Eponychial flap with optical elongation of the nail plate for ~1.5 mm (i, arrowhead). (k,l) Result 4 weeks after surgery.