Evaluation and diagnosis of acutetraumatic hand injuries

EVALUATION AND DIAGNOSIS OF ACUTE TRAUMATIC HAND INJURIES WAYNE PAN, MD, FRANK GIACOBETTI, MD, and JOHN S. TARAS, MD

In the management of acute hand injuries, the objective of the initial evaluation is to determine all damaged structures to deliver prompt and appropriate treatment. Advances in the fields of radiology and nuclear medicine have generated new diagnostic imaging techniques; however, recognition of the benefits and limitations of each method must be evaluated to determine their proper clinical applications. In today's cost-sensitive climate, it is important to arrive at an accurate diagnosis in the most efficient manner. KEY WORDS: hand injuries, diagnostic imaging, diagnostic modality

Hand injuries are among the most 'commonly seen orthopaedic injuries. Fractures involving the tubular bones of the hand represent the most frequent of all skeletal injuries. 1 A systematic and comprehensive evaluation provides the basis for a definitive diagnosis and effective treatment plan. The goal is to accurately identify all injuries and potential injuries at the initial evaluation so that appropriate care can be instituted in an expedient fashion. With the advancement of new technologies in the fields of radiology and nuclear medicine, there are many new diagnostic imaging techniques available to evaluate hand injuries. It is important to recognize the limitations of each imaging technique and to apply them to the appropriate clinical situation. With today's emphasis on medical cost-containment, costeffective algorithms need to be developed that will provide the most accurate diagnosis in the most efficient manner.

PREHOSPITAL AND EMERGENCY ROOM MANAGEMENT

area to reduce blood loss. The judicious use of proximally placed pneumatic tourniquets, however, is effective if direct pressure is not possible. It is recommended that tourniquets be inflated for no more than 2 hours at a time. After the bleeding has been adequately controlled, attention is next directed to keeping the wound free from further contamination, splinting all bony injuries, and carefully preserving the amputated part. The amputated part should be wrapped in a moist gauze dressing and placed in a clean plastic bag. This bag is then stored in another plastic bag containing an ice/water bath (40% ice/60% water). The amputated part should never directly contact the ice/water bath. This package should travel with the patient so that they arrive concurrently at the emergency room. Once in the emergency room, any amputated parts should be examined radiographically to assess the amount of bone loss and possible fracture.

HISTORY

From the Thomas Jefferson University Hospital, Philadelphia, PA. Address reprint requests to John S. Taras, MD, Clinical Assistant Professor of Orthopaedic Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, 19107. Copyright © 1997 by W.B. Saunders Company 1048-6666/97/0702-0009505.00/0

The evaluation of a hand injury continues in the emergency room, beginning with the patient's age, hand dominance, occupation, work status, and avocations. Other important issues that need to be addressed include known adverse drug reactions/allergies, current medications, tetanus status, medical history (diabetes, thyroid disease), surgical history, past h a n d / u p p e r extremity injuries, and social history (smoking, alcohol use, recreational drug use). Injuries that occur at work involving workers' compensation litigation should be approached carefully for potential secondary gain. The mechanism of injury should be determined. With injuries involving heavy machinery (printing presses, rollers), high-pressure injection, or high temperatures, the zone of injury may extend well beyond the superficial skin damage. One should always be aware of possible compartment syndrome in the hand, espedally with crush injuries. Noncontiguous injuries involving other joints of the ipsilateral upper or lower extremities also must be kept in mind, especially with injuries resulting from a fall or motor vehicle accident. Additional useful information includes time of injury (especially important with open injuries); medications received since injury (antibiotics, tetanus); and last oral intake (type of food and time). All of these pieces of

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After all life-threatening injuries have been addressed and the patient is medically stable, one can then begin to deal with the upper extremity trauma. It is important that all personnel involved in providing first aid in the field understand some general principles regarding the initial management of traumatic injuries to the upper extremity. These include immediately removing all rings and jewelry on the affected limb, using safe techniques for controlling bleeding, immobilizing the injured limb, preventing further wound contamination, and preserving and transporting any amputated part or parts along with the patient to an emergency room. Removal of rings and jewelry from the affected limb prevents possible further damage to the phalanges secondary to posttraumatic edema. This is especially important in patients unable to communicate. Bleeding can be another major problem in the field. It is safest to apply continuous direct pressure to the bleeding

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information from a solid basis from which to formulate an effective treatment plan.

PHYSICAL EXAMINATION Using the basics of a physical examination, inspection, palpation, percussion, and auscultation, one should be able to readily identify the region or regions of injury. Simple observation of the posture of the hand can give a tremendous amount of information. The normal hand in resting position lying supine is flexed at the metacarpophalangeal joints with a cascade of increasing degrees of flexion from the index to the small. This posture is disrupted in bone and tendon injuries. A flexor tendon injury results in an extended finger (Fig 1), whereas bony injuries exhibit deformities including rotation (Fig 2), shortening, and angular deviation (Fig 3). The regions of injury identified on the initial survey should be further classified with respect to (1) soft tissue integrity (open v closed wounds), (2) neurovascular integrity, (3) tendon injuries, and (4) bony injuries (fractures/dislocations). Ligamentous disruptions and associated carpal instability also should be identified. The Gustillo classification 2 is generally accepted as the standard for grading open fractures. Besides skin integrity, the location of the injur~ in relation to structures that are in danger should be noted. The nature of the wound, whether clean or contaminated, skin loss, and the condition of the skin edges should be noted. Neurovascular integrity is evaluated with inspection of the hand, looking for good capillary refill distally in the fingertips/nailbeds and good sensation to pinprick throughout the hand. Nonpalpable pulses may be assessed using a hand-held Doppler, especially in the digits. The relevant compartments should also be examined for increased pressures. The patient will complain of pain out of proportion to the apparent injury, and passive extension of the fingers will greatly worsen the discomfort. Increased pressure in the interosseous compartment is tested clinically by hyperextending each finger at the metacarpophalangeal joint, then flexing the finger fully at the interphalangeal joints, followed by radial and ulnar deviations. If the fingers cannot be placed in the intrinsic minus position or fully flexed without causing pain, there is enough increase

Fig 1. With a flexor' tendon laceration, loss of the normal flexed posture of the digit is observed. DIAGNOSIS OF HAND INJURIES

Fig 2. Rotational deformity results in scissoring of the digits with flexion.

in the interosseous compartment pressure to warrant decompression. 3 Sensation is tested on both sides of the digital pulps by measuring the Weber two-point discrimination (2PD), as popularized by Moberg. 4 This can be performed with a twisted paper clip. Increased 2PD (>6 m m for static; >3 m m for moving) 5 usually points to a lacerated nerve. Alternatively, a 256-Hz tuning fork can be used. Vibratory testing is less threatening, and therefore it is much easier to obtain patient cooperation. Nerve deficits distally also may be the result of much more proximal injuries; therefore, always evaluate the cervical spine as well as brachial plexus for other possible causes of neuropraxia. Assessment of muscles and tendons of the hand will show which tendons are functioning and which are lacerated. Differential testing of the flexor digitorum superficialis (Fig 4) and the flexor digitorum profundus (FDP) (Fig 5) of individual fingers is important in suspected tendon injuries. The FDP of the middle, ring, and small fingers share a common muscle belly; therefore, it is not possible for most people to flex the distal interphalangeal joints of these fingers independently. One should also be aware of flexor tendon avulsions. Avulsion of the flexor profundus tendon from its insertion is a common football injury and most often occurs in the ring finger. A proper assessment for flexor tendon lacerations involves appropriate digital blocking and testing of each specific joint. Extensor tendon injuries are usually easy to diagnose. A

Fig 3. Angular deviation is an obvious sign of skeletal injury,

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Fig 4. Testing FDS function.

mallet finger caused by extensor tendon rupture or from an avulsion with or without bone can be diagnosed by asking the patient to actively extend the distal phalanx while stabilizing the middle phalanx of the digit in question (Fig 6). Extensor tendon lacerations can usually be diagnosed clinically and confirmed with surgical exploration of the wound (Fig 7). Central slip ruptures of the extensor tendons can be more difficult to diagnose. Elson 6 described a test for diagnosing central slip ruptures. The suspected digit is flexed at 90 ° over the edge of a table at the proximal interphalangeal (PIP) joint. The examiner then asks the patient to actively extend the digit while applying resistence over the middle phalanx. In normal individuals with an intact central slip, one can only extend the PIP joint in this position of the finger. An intact central slip prevents the lateral bands from extending the distal interphalangeal (DIP) joint. In cases of central slip ruptures, active extension of the PIP joint will not be felt, but extension at the DIP joint will be seen because of the action of the subluxing lateral bands. Fractures and dislocations are usually fairly obvious, with concomitant pain, swelling, and tenderness, and are confirmed by plain radiographs. Collateral ligament ruptures such as gamekeeper's thumb are suspected by local pain and abnormal opening of the joint on stressing. Collateral ligament ruptures can be confirmed with stress

Fig 5. Testing FDP function. 88

Fig 6. Loss of terminal extension is seen in this mallet deformity.

radiographs aided with an infiltration of local anesthesia before stressing (Fig 8). In many cases, anesthesia is required to permit painless assessment of alignment and to permit closed reduction if necessary. The nerves to be blocked include the median, ulnar, superficial radial, and dorsal sensory ulnar either selectively or combined, depending on the particular injury. Five milliliters of 1% xylocaine are mixed with 0.5% bupivacaine (Marcaine; Winthrop Pharmaceuticals, New York, NY) both without epinephrine, and a 25-gauge needle is used. The median nerve is blocked 1.5 cm proximal to the carpal canal with the injection just radial and deep to the palmaris longus tendon. The superficial radial nerve is blocked 3 cm above the radial styloid by raising a transverse wheal over the radial side of the distal forearm. The ulnar nerve can be blocked by an injection under the flexor carpi ulnaris tendon just proximal to the wrist crease. Finally, the dorsal sensory branch of the ulnar nerve is blocked by raising a transverse wheal dorsally over the base of the fifth metacarpal.

DIAGNOSTIC IMAGING: PLAIN RADIOGRAPHS Initial radiographic workup of hand injuries includes a standard plain film series consisting of a minimum of three views: posterioanterior, lateral, and pronated oblique. Because a true lateral view of the hand obscures the individual details of each of the metacarpals and phalanges,

Fig 7. The extensor tendon laceration is confirmed by surgical exploration. PAN, GIACOBETTI,AND TARAS

Fig 8. Stress examination confirms ulnar collateral ligament disruption of this thumb's metacarpophalangeal joint.

modifications have been described to overcome this problem. Splaying of the individual digits enables better visualization of the phalanges. Lateral oblique views of the hand either 10° pronated or 10 ° supinated allows for improved imaging of the second and third metacarpals or fourth and fifth metacarpals, respectively. The Brewerton view, a posterioanterior projection 15 ° ulnar to vertical with the metacarpophalangeal joint flexed at 65 °, provides a clear picture of the metacarpal heads. If the injury is confined to a single digit, the radiographic examination should be limited to the posterioanterior, lateral, and oblique views of that digit to provide greater detail. Thumb injuries are best visualized with a Robert's projection (Fig 9), a true anteroposterior projection with the thumb in extreme pronation. This view provides a clear view of the articulation of the trapezium with the base of the first metacarpal In addition, stress views of the thumb are useful in detecting ligamentous instability, as in ulnar collateral ligament tears. Standard radiographic examination of the wrist includes the following projections: posteroanterior with the wrist in neutral, posteroanterior with the wrist and hand in ulnar deviation, a lateral projection, and a 45 ° pronation oblique view. On the posteroanterior neutral view, disruption of any of the three carpal arcs indicates a subluxation or dislocation of the carpal bones (Fig 10). The carpal arcs, originally described by Gilula, are formed by the joining of

Fig g. A Robert's view of the thumb is useful in identification of first carpometacarpal joint fractures and dislocations. DIAGNOSIS OF HAND INJURIES

Fig 10. Loss of the smooth arcs formed by the proximal carpal row indicates a carpal dislocation.

the proximal (arc 1) and distal (arc 2) articular margins of the proximal carpal row and proximal articular margin of the capitate and hamate (arc 3). With the wrist in maximal ulnar deviation, the posteroanterior view provides the best view of the waist of the scaphoid, which is a common site of fracture (Fig 11). The navicular fat stripe (NFS) is another radiographic landmark that if displaced or obliterated indicates an injury to the radial side of the wrist. Seen in more than 90% of adult wrist films on the posteroanterior projection, the NFS is a thin radiolucent line that parallels the lateral surface of the scaphoid. Fractures of the scaphoid, radial styloid, base of the first metacarpal or the trapezium are associated with displacement of the NFS. On the lateral wrist view with the wrist in neutral position, the axial relationship between the hand, wrist, and forearm can be easily appreciated. Alignment of the third metacarpal with the capitate, the proximal pole of the capitate with the lunate, and the lunate with the radius should be clearly demonstrated. The central axes of these three bones should be within 10 ° of coaxial. The scaphoidlunate angle (SLA) can be seen on this view. A normal SLA should be between 30 ° and 60 ° (average, 47°). A dorsiflexion or DISI instability pattern can be demonstrated radiographically if the SLA is greater than 80 °. A palmar flexion

Fig 11. Suspected scaphoid injuries should be evaluated with a PA radiograph with the wrist in ulnar deviation and slight extension. 89

or VISI instability pattern can be seen if the SLA is less than 30 ° . A line drawn on the volar and dorsal surfaces of these three bones (volar radial line and dorsal radial line) can be used to determine dislocations of the lunate and mid carpus. Displacement of the lunate with axial alignment of the capitate and the radius indicates a disruption of the capitolunate and lunatoradial joints or a lunate dislocation. Displacement of the capitate with axial alignment of the lunate and radius indicates a disruption of the capitolunate joint or a perilunate dislocation. Displacement of both the lunate and capitate occur with a midcarpal dislocation. Fractures of the scaphoid, capitate, triquetrum, and styloid processes of the radius and ulna are commonly associated with these dislocations. The 45 ° pronation oblique view shows the articulation between the trapezium and trapezoid as well as the scaphotrapezium, scaphocapitate, and lunocapitate joints. A 45 ° supination oblique view with the wrist in extension shows the pisiform-triquetral joint in parallel as well as the hook of the hamate (Fig 12). A carpal tunnel view can provide another view of the hook of the hamate as well as an excellent view of the volar surfaces of the trapezium, scaphoid, capitate, and lunate (Fig 13).

Fig 13, The carpal tunnel view is an alternate way of identifying hook of hamate fractures,

Nuclide bone scanning is a useful adjunct to plain radiographs when there is a strong clinical suspicion of a fracture in the face of normal-appearing plain films. It is frequently used to identify occult scaphoid, hook of the hamate, and volar tubercle of the trapezium fractures (Fig 14). In addition, bone scans can also be used to follow the progress of fracture healing. Technetium-99 (metastable)-labeled phosphate compounds are the radiopharmaceuticals of choice for bone scanning. The standard used for musculoskeletal imaging is methylene diphosphonate, because of its rapid renal clearance characteristics and higher bone/background ratios. At 2 hours postinjection, the distribution of the labeled compound is 10% in blood, 50% in bone, and 40% in urine. Uptake of the radiolabeled compound is related to its

blood supply, vascular permeability, and rate of bone turnover (osteoblastic activity). The fracture site will accumulate radionuclide in 80% of patients within 24 hours and up to 95% of patients within 72 hours. 7 Typically, those with a delayed uptake are older than 65 years of age, which also accounts for the higher false-negative rate in this population; however, a site of increased uptake does not always indicate a fracture. Because of the nonspecificity of bone scans, problems with interpretation can arise. Periosteal tears and ligament avulsions can also cause a transient increase in nuclide activity. Serial scans can be performed to help clarify the situation, because true fractures will remain "hot" for up to 4 weeks. Many studies have been performed with regard to the efficacy of bone scans in detecting occult scaphoid fractures. Patients with a clinically suspicious examination but negative plain radiograph should be immobilized immediately with a below-elbow splint with the thumb held in abduction. They should then be refered for a follow-up bone scan after 72 hours. If positive, then immobilization should be continued. If negative, then immobilization can be safely discontinued. Although postinjury day 4 bone scans are an accurate means of ruling out scaphoid fracture (negative predictive value of 100%), they do not always

Fig 12. The semisupinated view is valuable in identifying fractures of the hamate hook as seen in this radiograph.

Fig 14. Osseous injuries not apparent after review of standard radiographs can be identified by a bone scan, as in this case of an occult scaphoid fracture.

DIAGNOSTIC IMAGING: NUCLEAR MEDICINE STUDIES

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PAN, GIACOBETTI,AND TARAS

confirm the diagnosis of a scaphoid fracture (positive predictive value of only 65%); therefore, other modalities should be considered if there are conflicting data. Single photon emission computed tomography is another modality that produces tomographic images in multiple planes. Occasionally, it can identify abnormalities that are missed on routine bone scan studies.

DIAGNOSTIC VIBRATION

MODALITY: INTRASOUND

Intrasound vibration has been shown to be useful in diagnosing occult scaphoid fractures. Using a hand-held vibration apparatus that emits a 100-mW vibration with a frequency of between 200 and 8,500 Hz, all patients with a positive bone scan were also identified as having a scaphoid fracture by the intrasound technique with 100% sensitivity and 95% specificity. This unique test provides a simple, inexpensive, nonionizing, noninvasive, safe alternative to current standard methods for detecting occult scaphoid fractures. 8

DIAGNOSTIC RESONANCE

IMAGING: MAGNETIC IMAGING

The advent of magnetic resonance imaging (MRI) has provided a new, noninvasive approach for examination of the wrist that allows simultaneous visualization of the bones and soft tissues. Raduionuclide bone scanning, the most widely used imaging modality for documenting occult fractures, may be less reliable than MRI, especially if performed within 24 hours of injury. MRI has shown fractures after just 3 hours from injury. 9 The major indications for MRI of the wrist include ligamentous disruption, ulnar-sided pain that may be the result of an abnormality of the TFCC (Fig 15), and evaluation of palpable masses. 1° Nondisplaced scaphoid fractures also can often present a diagnostic dilemma. Recent studies have also shown lowfield MRI to be specific for diagnosing scaphoid fractures3 ~ Other indications include osteonecrosis, infection, and arthritidies, particularly inflammatory forms. MRI, by eliminating diagnostic uncertainty, may obviate the need

for hospital admissions or return visits for definitive resolution.

DIAGNOSTIC

IMAGING: ARTHOSCOPY

Wrist arthroscopy was first reported by Professor Kenji Takagi ~2 in 1920. However, it was not until the mid-1980s that wrist arthroscopy was taught on a widespread basis. The indications for wrist arthroscopy are both diagnostic and therapeutic. We limit our focus to the diagnositic indications only. No other diagnositic modality permits such an accurate evaluation of static and dynamic pathology. Arthroscopy allows assessment of the stability of intraarticular structures and the measurement of defect sizes. Indications for diagnostic arthroscopy include (1) assessment of ligamentous injuries of the wrist (including scapholunate ligament disruption, lunotriquetral disruptions, and TFCC disorders); (2) assessment of chondral defect; and (3) assessment of wrist pain of unknown causes. Neither arthrography nor MRI provide a satisfactory method for identifying scapholunate tears or cartilage abnormalities. Cooney 13recently reported a high incidence of false positives and negatives when evaluating interosseous ligaments with arthrography. Arthrography does not quantify the size or type of perforation or provide information about adjacent structures such as articular cartilage and synovium. A further concern is that patients with a positive arthrogram have up to a 74% chance of having a positive arthrogram on the asymptomatic contralateral wrist. ~4 MRI, a noninvasive diagnostic modalit~ has been reported as a poor detector of cartilage erosions 15,16and to have a sensitivity rate of only 25% with an accuracy of 64% for scapolunate ligament tears. 17Arthroscopy allows direct inspection of the pathological morpholog)~ which can give valuable information about the extent of the injuries and the associated injuries that were not fully appreciated on clinical examination.

SUMMARY Evaluation and assessment of the injured hand is conducted to plan proper management of the acute injury. A thorough history and proper physical examination is vital for the evaluation process. Although there are many new imaging and other diagnostic techniques available to evaluate hand injuries, it is important to recognize the limitations of each imaging technique and apply them appropriately to the clinical situation. With the emphasis today on medical cost containment, it is important to arrive at an accurate diagnosis in the most economical manner.

REFERENCES

Fig 15. MRI is particularly useful in visualizing the triangular fibrocartilage and can confirm tears when suspected by clinical evaluation.

DIAGNOSIS OF HAND INJURIES

1. SwansonAB: Fractures involving the digits of the hand. Orthop Clin North Am 1:261-274,1970 2. Gustflo RB, Mondoza RM, Williams DN: Problems in the management of type III open fractures: A new classificationof type III open fractures. J Trauma 24:742-746,1984 3. Spinner M, AiachoA, Silver L, et al: Impending ischemic contracture of the hand. Plast ReconstrSurg 50:341-349,1972 4. MobergE: Evaluation of the sensibilityin the hand. Surg Clin North Am 40:357,1977

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5. Dellan AL, Mackinnon SE, Crosby PM: Rehability of two-point discriminationmeasurements. J Hand Surg 12A:693-696, 1987 6. Elson RA: Rupture of the central slip of the extensor hood of the finger: A test for early diagnosis. J Bone Joint Surg Br 68:229-231,1986 7. Matin P: The appearance of bone scans following fractures, including intermediate and long-term studies. J Nucl Med 20:1227,1979 8. Finkenberg JG, Hoffer E, Kelly C, et ah Diagnosis of occult scaphoid fractures by ultrasound vibration. J Hand Surg 18A:4-7, 1993 9. Feldman F: MR imaging: Its role in detecting occult fracture. Skel Radio123:439, 1994 10. Yu J: Magnetic resonance imaging of the wrist. Orthopedics 17:10411048, 1994 11. Lepisto J: Low field MRI and scaphoid fractures. J Hand Surg [Br] 20:539-542,1995 12. Takagi K: The classic arthroscope. Clin Orthop 167:6-8,1982

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13. Cooney WP: Evaluation of chronic wrist pain by arthrography, arthroscopy, and arthrotomy. J Hand Surg [Am] 18:815-822, 1993 14. Herbert TJ, Faithfull RG, McCann DJ, et ah Bilateral arthrography of the wrist. J Hand Surg [Br] 15:233-235,1990 15. Cerofolini E, Luchetti R, Pederzini L, et ah MRI evaluation of triangular fibrocartilage complex tears in the wrist: Comparison with arthography and arthroscopy. J Comput Assist Tomogr 14:963-967, 1990 16. Wang HS, Kindynis P, Brat~rne SA, et ah Triangular fibrocartilage study with gross pathologic and histologic correlation. Radiology 181:401-404,1991 17. Schweitzer ME, Brahme SA, Hedler J, et al: Chronic wrist pain: Spin-echo and short tau inversion recovery MR imaging and conventional and MR/arthrography. Radiology 182:205-211,1982

PAN, GIACOBETTI,AND TARAS