**2. Clinical presentation**

The crush injury may present from the tip of the finger to proximally right up to the arm. Although the management of more proximal and therefore potentially life-threatening injuries is precluded from this chapter, we will deal briefly with their management. There are certain principles in the management of all injuries be they minor or major (**Table 1**), and these have to be adhered to, especially if it is a high-energy trauma as in a road traffic accident (RTA) or a fall from a height.

Thus, the primary aim in any trauma is to stabilize the patient and rule out any life-threatening injuries. Airway, breathing and circulation must be first secured. Subsequent management will focus on the limb at hand and its systemic sequelae. After the early treatment and resuscitation of the patient, antibiotic and tetanus cover is ensured and the hand surgeon alerted for further assessment.

#### **2.1. Clinical assessment**

*The most important part in the management of the crushed hand is the assessment.* The crush injury has to be given due respect because neglect in adequate assessment will result in poor functional outcome or unacceptable cosmesis. Thus, a judgment call by an experienced hand surgeon for all tissue components i.e., skin and its contents (tendon, bone, joint, vessels, nerves and muscles), is essential. The aim of the treatment is to provide the hand with basic hand functions most importantly: functioning *pincer mechanism* and *sensation for grasping* (**Figure 1**).

*2.1.2. History*

feel one or two points on their fingertip.

assessed carefully.

The injury may be small involving just the digits or the hand, or it may be more extensive including the wrist and even the forearm. It may even be segmental with intervening areas of normal tissue. It may be open or closed, with associated elements of degloving or avulsion. They may be either clean as in door jamb injuries or obviously dirty as the trash compactor or farm injuries. One must also be alerted to marine-related open wounds with their own peculiar pathogens (*Mycobacterium marinum*). It may be contaminated with paint or grease and be sustained in a high-pressure printing press (see previous chapter, **Figure 13**) or injection mechanism (**Figure 3**). Aggravating factors such as friction burns, industrial hot pressure injuries, multidirectional forces and contamination should be

**Palmar skin Dorsal skin**

2. Thick cornified surface Thin 3. Immobile skin Mobile 4. High-density sensory receptors Less dense

**Table 2.** Comparison of specialized tissue in palmar & dorsal surfaces.

1. Specialized glabrous epithelium Nonglabrous, hirsute

5. Subcutaneous pulp Nail matrix & plate

**Figure 1. A**–**D:** Of the four basic functions above, the pincer mechanism or "pinch" function is most useful. Pictures taken from Dr. Lim Beng Hai. **E:** Dorsal skin is thinner and pliable. **F:** A two-point discriminator (2-PD) used to measure sensation, which an unfolded paperclip too can do. The patient is first shown the device and explained how it is used to

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#### *2.1.1. Functional anatomy of the hand*

The hand is basically composed of two types of skin, thick palmar glabrous skin and thin dorsal skin. As can be seen in **Figure 1E**, the dorsal skin is thin, loose, mobile and stretchable. The palmar side, however, is thickened for protection with papillary ridges to increase the surface area as well as improve the grip. These ridges form our finger prints. The fingers are highly innervated to provide a two-point discrimination of 4–6 mm at the fingertip, as measured by the two-point discriminator disc (2-PD: **Figure 1F**). The sweat glands give lubrication to aid in feeling and function (**Table 2**).

There are numerous flexure creases to anchor the skin down, and with the palmaris brevis muscle, they aid in holding and gripping objects. The muscles of the hypothenar and thenar eminences allow specialized functions of opponens, abduction, adduction and flexion (**Figure 2**).

**Table 1.** Principles of management of crush injury.

• Life before limb

• Limb can endanger life e.g., compartment syndrome, infection

**Figure 1. A**–**D:** Of the four basic functions above, the pincer mechanism or "pinch" function is most useful. Pictures taken from Dr. Lim Beng Hai. **E:** Dorsal skin is thinner and pliable. **F:** A two-point discriminator (2-PD) used to measure sensation, which an unfolded paperclip too can do. The patient is first shown the device and explained how it is used to feel one or two points on their fingertip.

#### *2.1.2. History*

**2. Clinical presentation**

106 Essentials of Hand Surgery

alerted for further assessment.

*2.1.1. Functional anatomy of the hand*

in feeling and function (**Table 2**).

thorax, intra-abdominal injury

• Secondary survey of traumatized limb

**Table 1.** Principles of management of crush injury.

• Limb can endanger life e.g., compartment syndrome, infection

• Thorough assessment—primary survey of the patient as a whole

• Life before limb

**2.1. Clinical assessment**

The crush injury may present from the tip of the finger to proximally right up to the arm. Although the management of more proximal and therefore potentially life-threatening injuries is precluded from this chapter, we will deal briefly with their management. There are certain principles in the management of all injuries be they minor or major (**Table 1**), and these have to be adhered to, especially if it is a high-energy trauma as in a road traffic accident (RTA) or a fall from a height. Thus, the primary aim in any trauma is to stabilize the patient and rule out any life-threatening injuries. Airway, breathing and circulation must be first secured. Subsequent management will focus on the limb at hand and its systemic sequelae. After the early treatment and resuscitation of the patient, antibiotic and tetanus cover is ensured and the hand surgeon

*The most important part in the management of the crushed hand is the assessment.* The crush injury has to be given due respect because neglect in adequate assessment will result in poor functional outcome or unacceptable cosmesis. Thus, a judgment call by an experienced hand surgeon for all tissue components i.e., skin and its contents (tendon, bone, joint, vessels, nerves and muscles), is essential. The aim of the treatment is to provide the hand with basic hand functions most importantly: functioning *pincer mechanism* and *sensation for grasping* (**Figure 1**).

The hand is basically composed of two types of skin, thick palmar glabrous skin and thin dorsal skin. As can be seen in **Figure 1E**, the dorsal skin is thin, loose, mobile and stretchable. The palmar side, however, is thickened for protection with papillary ridges to increase the surface area as well as improve the grip. These ridges form our finger prints. The fingers are highly innervated to provide a two-point discrimination of 4–6 mm at the fingertip, as measured by the two-point discriminator disc (2-PD: **Figure 1F**). The sweat glands give lubrication to aid

There are numerous flexure creases to anchor the skin down, and with the palmaris brevis muscle, they aid in holding and gripping objects. The muscles of the hypothenar and thenar eminences allow specialized functions of opponens, abduction, adduction and flexion (**Figure 2**).

• Look for proximal hidden injuries which can be fatal e.g., head injury, cervical spine injury, associated pneumo-

The injury may be small involving just the digits or the hand, or it may be more extensive including the wrist and even the forearm. It may even be segmental with intervening areas of normal tissue. It may be open or closed, with associated elements of degloving or avulsion. They may be either clean as in door jamb injuries or obviously dirty as the trash compactor or farm injuries. One must also be alerted to marine-related open wounds with their own peculiar pathogens (*Mycobacterium marinum*). It may be contaminated with paint or grease and be sustained in a high-pressure printing press (see previous chapter, **Figure 13**) or injection mechanism (**Figure 3**). Aggravating factors such as friction burns, industrial hot pressure injuries, multidirectional forces and contamination should be assessed carefully.

**Table 2.** Comparison of specialized tissue in palmar & dorsal surfaces.

*2.1.3. Examination*

*2.1.4. General factors*

cascade of the hand elicited by the squeeze test.

Initial assessment in the emergency room can be conducted while obtaining the history from the patient and observing the hand posture, cascade (**Figure 4**), color as well as assessing flexor and extensor mechanisms even without exposing the wound. Local anaesthesia should only be given *after* a sensory examination has been performed, preferably with a 2-PD disc (**Figure 1F**). If delay to theater is expected, a lavage under some local anesthesia maybe performed as necessary. Swabs should be taken if it is potentially contaminated or infection suspected. A more thorough evaluation of the extent of injuries can then be made in the operating theater under general anesthesia and tourniquet control. The assessment should be thorough, with minimum number of wound inspections and made with the surgical treatment options in mind (**Table 3**). In order to make the choice to replant, reconstruct or amputate, a number of factors have to be taken into consideration (**Table 4**). These deciding factors will influence the surgeon's final decision.

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The patient's general condition is of prime importance in making a decision since an elderly patient in hypovolemic shock would not be able to tolerate further ischemic insult in terms of prolonged operative time and potential blood loss implicated in reconstruction or limb salvage. Similarly, a patient with diabetes would be more prone to infection and complications. In contrast, severe crushing to a contralateral limb would necessitate more extreme measures to attempt salvage. There has been no consensus achieved yet on the maximum time

**Figure 4. A:** Damage to flexor tendons of the index and small fingers can be seen in the flattened posture of those fingers. The index finger cannot be flexed at the DIPJ indicating an intact FDS but a severed FDP (FDS finger). **B:** adequate exposure by gentle retraction with skin hooks and meticulous repair of both FDS and FDP, allows good motion within the sheaths. **C:** restoration of the normal cascade. **D:** the chiasma of the superficialis (tenotomy scissors) opens out and from a volar position proximally, curves 180° to insert dorsal to the FDP on the base of the middle phalanx distally. **E:** in another patient, the small finger cannot be flexed at the DIPJ indicating an intact FDS but a severed FDP. **F:** normal

**Figure 2. A–D** Movements of the thumb: opposition, flexion, extension and abduction. All of these combine to perform circumduction.

The patient's occupation, associated medical conditions and allergies if any, and dominant hand should be recorded.

**Figure 3.** Paint injection injury. **A:** a very small entry point, **B:** but once explored, the extensive damage can be seen. The paint is toxic and needs to be painstakingly cleared. **C:** assessment of nerve function using a 2-PD disc. The test is administered on the normal hand first, then only on the affected digit with the patient's keeping their eyes closed. Just enough pressure needs to be applied so as to lightly blanch the skin.

#### *2.1.3. Examination*

Initial assessment in the emergency room can be conducted while obtaining the history from the patient and observing the hand posture, cascade (**Figure 4**), color as well as assessing flexor and extensor mechanisms even without exposing the wound. Local anaesthesia should only be given *after* a sensory examination has been performed, preferably with a 2-PD disc (**Figure 1F**). If delay to theater is expected, a lavage under some local anesthesia maybe performed as necessary. Swabs should be taken if it is potentially contaminated or infection suspected. A more thorough evaluation of the extent of injuries can then be made in the operating theater under general anesthesia and tourniquet control. The assessment should be thorough, with minimum number of wound inspections and made with the surgical treatment options in mind (**Table 3**).

In order to make the choice to replant, reconstruct or amputate, a number of factors have to be taken into consideration (**Table 4**). These deciding factors will influence the surgeon's final decision.

#### *2.1.4. General factors*

The patient's occupation, associated medical conditions and allergies if any, and dominant hand should be recorded.  Paint injection injury. **A:** a very small entry point, **B:** but once explored, the extensive damage can be seen. The paint is toxic and needs to be painstakingly cleared. **C:** assessment of nerve function using a 2-PD disc. The test is administered on the normal hand first, then only on the affected digit with the patient's keeping their eyes closed. Just

enough pressure needs to be applied so as to lightly blanch the skin.

**Figure 2. A–D** Movements of the thumb: opposition, flexion, extension and abduction. All of these combine to perform

the history.

circumduction.

108 Essentials of Hand Surgery

The patient's general condition is of prime importance in making a decision since an elderly patient in hypovolemic shock would not be able to tolerate further ischemic insult in terms of prolonged operative time and potential blood loss implicated in reconstruction or limb salvage. Similarly, a patient with diabetes would be more prone to infection and complications. In contrast, severe crushing to a contralateral limb would necessitate more extreme measures to attempt salvage. There has been no consensus achieved yet on the maximum time

**Figure 4. A:** Damage to flexor tendons of the index and small fingers can be seen in the flattened posture of those fingers. The index finger cannot be flexed at the DIPJ indicating an intact FDS but a severed FDP (FDS finger). **B:** adequate exposure by gentle retraction with skin hooks and meticulous repair of both FDS and FDP, allows good motion within the sheaths. **C:** restoration of the normal cascade. **D:** the chiasma of the superficialis (tenotomy scissors) opens out and from a volar position proximally, curves 180° to insert dorsal to the FDP on the base of the middle phalanx distally. **E:** in another patient, the small finger cannot be flexed at the DIPJ indicating an intact FDS but a severed FDP. **F:** normal cascade of the hand elicited by the squeeze test.

**Table 3.** Surgical treatment options.

**Table 4.** Assessment of general factors & local factors.

an amputated part of a limb can tolerate ischemia and gain good functional postreplantation. Many factors are involved such as ambient temperature, collateral circulation and level of amputation. Many attempts have been made to assist in this decision-making process but none are ideal. Although MESS (**Table 5**: Mangled Extremity Scoring System) was initially developed for the lower limb [1], it has subsequently been applied to the upper limb as well with some degree of success, provided one knows its limitations [2, 3]. In this score, a total of six implies the limb is salvageable, while seven or more advocates amputation. The score, however, does not take into consideration other major injuries causing hypovolemia, associated medical conditions, injuries to the other limbs that may necessitate salvage, nerve injuries and the type of damage sustained, and a more subdivided range of ages. The latter is important in that an infant would have better nerve regeneration capabilities than an adult, whereas a 90-year-old would have less cardiovascular reserve than a 50-year-old, both situations not being differentiated. The exact mechanism of injury (crush, avulsion, guillotine), as well as the amount of force, its velocity & the width of the offending object are all important factors in decision-making. Smith et al. suggested three contraindications to major replantation, namely brachial plexus avulsion, severely mangled extremity and an excessive ischemia time [4]. There have been many advances since then to overcome some of these obstacles, for example, highly innovative developments in the field of neuromuscular prosthetics; however, brachial plexus avulsion remains challenging. There will come a time though when an equilibrium will be reached in the two arms.

*2.1.5. The five P's*

**Skeletal/soft tissue injury**

Limb ischemia

Age

Shock

• Pain

• Paresthesia

• Paralysis

• Cold limb

• Pallor

described as the 5 P's namely:

**Table 5.** Mangled extremity severity score.

• Pulselessness and additionally a

The most important aspect in the assessment of the limb will be the *vascularity*. Traditionally

• Low energy (stab, fracture, civilian gunshot wound) 1 • Medium energy (open or multiple fracture) 2 • High energy (military gunshot wound, crush) 3 • Very high energy (+gross contamination) 4

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• Pulse reduced or absent but perfusion normal 1 • Pulseless, diminished capillary refill 2 • Pt is cool, paralyzed, insensate, numb 3

• <30 0 • 30–50 1 • >50 2

• Systolic BP always >90 mmHg 0 • Systolic BP transiently <90 mmHg 1 • Systolic BP persistently <90 mmHg 2

Pain, paresthesia and paralysis may not be detected in the head injured patient, patients that are heavily sedated, or those with brachial plexus injuries. Pallor may be unreliable in certain situations such as hypovolemic shock, massive blood loss, pigmented individuals and compartment syndrome. Dyes and other coloring materials as well as grease have to be scrubbed off in order to properly assess the circulation. Other parameters such as capillary refill, bleeding on pin prick, and transcutaneous oxygen pulse pressure may be used as an adjunct in the assessment.

**Table 5.** Mangled extremity severity score.

#### *2.1.5. The five P's*

The most important aspect in the assessment of the limb will be the *vascularity*. Traditionally described as the 5 P's namely:

• Pain

an amputated part of a limb can tolerate ischemia and gain good functional postreplantation. Many factors are involved such as ambient temperature, collateral circulation and level of amputation. Many attempts have been made to assist in this decision-making process but none are ideal. Although MESS (**Table 5**: Mangled Extremity Scoring System) was initially developed for the lower limb [1], it has subsequently been applied to the upper limb as well with some degree of success, provided one knows its limitations [2, 3]. In this score, a total of six implies the limb is salvageable, while seven or more advocates amputation. The score, however, does not take into consideration other major injuries causing hypovolemia, associated medical conditions, injuries to the other limbs that may necessitate salvage, nerve injuries and the type of damage sustained, and a more subdivided range of ages. The latter is important in that an infant would have better nerve regeneration capabilities than an adult, whereas a 90-year-old would have less cardiovascular reserve than a 50-year-old, both situations not being differentiated. The exact mechanism of injury (crush, avulsion, guillotine), as well as the amount of force, its velocity & the width of the offending object are all important factors in decision-making. Smith et al. suggested three contraindications to major replantation, namely brachial plexus avulsion, severely mangled extremity and an excessive ischemia time [4]. There have been many advances since then to overcome some of these obstacles, for example, highly innovative developments in the field of neuromuscular prosthetics; however, brachial plexus avulsion remains challenging. There will come a time though when an equilibrium will

7. Mechanism of Injury

be reached in the two arms.

1. Replantation

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2. Resurfacing with skin graft

4. Revision amputation

3. Reconstruct with flap (local or free)

**Table 3.** Surgical treatment options.

5. Rehabilitation—potential prosthesis/orthosis

**Table 4.** Assessment of general factors & local factors.

**General factors Local factors** 1. Age 1. Circulation 2. Circulatory stability 2. Sensation

4. Associated medical problems 4. Loss of skin

3. Life-threatening conditions 3. Tendon movements

5. Injury to contralateral limb 5. Loss of bone & joints 6. Time lapse—warm & cold ischemia tissue 6. Loss of specialized tissue

Pain, paresthesia and paralysis may not be detected in the head injured patient, patients that are heavily sedated, or those with brachial plexus injuries. Pallor may be unreliable in certain situations such as hypovolemic shock, massive blood loss, pigmented individuals and compartment syndrome. Dyes and other coloring materials as well as grease have to be scrubbed off in order to properly assess the circulation. Other parameters such as capillary refill, bleeding on pin prick, and transcutaneous oxygen pulse pressure may be used as an adjunct in the assessment.

#### *2.1.6. Specific structures*

**Neurological** damage also has to be outlined prior to exploration and also to prepare the surgical field in case a nerve graft is required. Gross sensation being inadequate, two-point discrimination should be used whenever possible to ascertain neurological deficit. Failure to differentiate 8 mm is the cutoff point where damage is certain.

Assessment of **tendons** can be tricky, especially if an adjacent nerve is also damaged or if the injury is closed. The best way to assess tendon damage is to observe the **resting posture** of the hand (**Figure 4C**). The unmistakable cascade of increasing flexion from the index to the little fingers is lost if there is any incontinuity. Complete division of both flexor tendons to the digits results in a straight finger in comparison with the adjacent flexed digits (**Figure 4A**). Division of the flexor digitorum profundus (FDP) straightens out the DIP joint (**Figure 4E**). A cut flexor digitorum superficialis (FDS) alone may not produce any visible abnormality (**Figure 4A**); however, a partial tear may be diagnosed by eliciting pain while stress testing the affected tendon. In a child or semiconscious adult, flexion may be reproduced by squeezing the forearm volar surface (**Figure 4F**). All these subtle differences should be looked for in the initial examination. **Flexor tendons** are tough structures and usually the last to be severed. Nonetheless, they are not easily replaced, having an intricate anatomy and biomechanism not completely reproducible. Therefore, it follows that they should be debrided with care.

**Extensor tendons** may be partially or totally cut presenting in a spectrum from a closed mallet, to just weakness in extension, or complete inability to extend the finger. Extension should be tested against resistance and if weak may indicate either a partial tear, damage to the collateral bands, or a single tendon cut in a dual tendon finger such as the index or little fingers. Avulsion of the central slip may present as a boutonniere deformity (**Figure 5**). Patency of the central slip is determined by Elson's test, where the finger is tested against resistance with the PIP is flexed 90° over the edge of a table and resistance applied to active extension [5]. If the central slip is avulsed, the PIP extension will be weak and the DIP will be rigid [6].

**Skin** is assessed both from the history and then examination. A roller or roll-over injury suggests degloving (**Figure 6**), which can be more extensive than the wound implies. Bleeding from the wound edge and to pin-prick, color of the skin and separation from the underlying subcutaneous plane all play an important role. If the color is pink with active bleeding and a rapid refill, circulation is intact. If the color is slightly dusky, and the refill is rapid but bleeding is dark in color, there may be venous congestion. If, however, the skin is pale and refill is poor, revascularization may be necessary. A note is made to the patient and his family, of the

**Figure 6. A:**A 35 year old sustained a highly comminuted fracture of the distal end of her tibia and fibula. **B:** She also had a *severe degloving injury* (arrow) with partial loss of skin cover. **C:** Meticulous reconstruction with wires, screws and basic principles. **D:** Stabilization with an external fixator and skin graft posteriorly. **E:** Good healing 3 months later with

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If **radiographs** from the emergency room are not satisfactory in assessing the **bony** injury, it may be necessary to repeat them either after splintage or in the operating room This would aid in assessing the damage accurately and also in planning the implants to be used in the repair or reconstruction of the skeletal framework. Ideally, anteroposterior and lateral films should be available, and preferably oblique as well if the fracture configuration is complex. Torsional injuries may require reduction and splintage in position prior to radiographic evaluation. It may save time to order chest and cervical radiographs for the preoperative

After a relevant detailed history and thorough examination, the patient is worked up for the operative procedure. The assessment is targeted to evaluating his general condition and co-morbidities

assessment if the patient is older and general anesthesia is required for surgery.

possible flaps, both local and distant that may be required.

**3. Management**

relatively normal gait.

**3.1. Preoperative assessment**

**Figure 5. A:**The central slip is torn (black arrow), and this incontinuity will result in difficulty for the PIP joint to be extended. **B:** The finger can still be extended (weakly) through the lateral bands, which are intact and inserted via the terminal tendon into the distal phalanx. **C:** If the central slip is intact; however, the P3 will be "floppy" **(D)** While extending the PIPJ in flexion. See video by Dr. Mike Hayton: https://youtu.be/G9HY0qXWUvE [6].

**Figure 6. A:**A 35 year old sustained a highly comminuted fracture of the distal end of her tibia and fibula. **B:** She also had a *severe degloving injury* (arrow) with partial loss of skin cover. **C:** Meticulous reconstruction with wires, screws and basic principles. **D:** Stabilization with an external fixator and skin graft posteriorly. **E:** Good healing 3 months later with relatively normal gait.

**Skin** is assessed both from the history and then examination. A roller or roll-over injury suggests degloving (**Figure 6**), which can be more extensive than the wound implies. Bleeding from the wound edge and to pin-prick, color of the skin and separation from the underlying subcutaneous plane all play an important role. If the color is pink with active bleeding and a rapid refill, circulation is intact. If the color is slightly dusky, and the refill is rapid but bleeding is dark in color, there may be venous congestion. If, however, the skin is pale and refill is poor, revascularization may be necessary. A note is made to the patient and his family, of the possible flaps, both local and distant that may be required.

If **radiographs** from the emergency room are not satisfactory in assessing the **bony** injury, it may be necessary to repeat them either after splintage or in the operating room This would aid in assessing the damage accurately and also in planning the implants to be used in the repair or reconstruction of the skeletal framework. Ideally, anteroposterior and lateral films should be available, and preferably oblique as well if the fracture configuration is complex. Torsional injuries may require reduction and splintage in position prior to radiographic evaluation. It may save time to order chest and cervical radiographs for the preoperative assessment if the patient is older and general anesthesia is required for surgery.