SCAPHOID INJURY

SCAPHOID INJURY

Scaphoid fracture is the most common type of bone fracture in the carpus (ie, wrist).

Frequently, however, the diagnosis of this scaphoid injury is delayed; a delay in the diagnosis and treatment of a scaphoid fracture may alter the prognosis for union, increase the risk of avascular necrosis, and dramatically increase the long-term likelihood of arthritis.

PATHOPHYSIOLOGY

ANATOMIC CONSIDERATIONS

The carpus contains 8 small bones, which are arranged in 2 rows, proximal and distal. The proximal bones, from the radial to the medial side, are the scaphoid, lunate, triquetrum, and pisiform.

Only the scaphoid and lunate articulate with the radius; thus, these 2 bones transmit the entire force of a fall on the hand to the forearm. The distal bones are, starting from the radial side, the trapezium, trapezoid, capitate, and hamate.

BLOOD SUPPLY

Anatomically, the scaphoid may be divided into proximal, middle (termed the waist), and distal thirds. Most of the blood supply to the scaphoid enters distally.

The proximal part of the scaphoid has no blood vessels entering it, depending instead on vessels that pierce the midportion. Fractures of the proximal third of the scaphoid account for 20% of scaphoid fractures, those of the middle portion account for 60%, and fractures of the distal part make up the remaining 20%.

Diminished blood flow to the proximal pole is noted in about one third of fractures at the waist level. This reduced blood supply may result in avascular necrosis of the proximal pole of the scaphoid.

Almost 100% of proximal pole fractures result in aseptic necrosis. Displaced scaphoid fractures have a nonunion rate of 55-90%.

FALL ONTO OUTSTRETCHED HAND

The usual mechanism of injury is a fall onto the outstretched hand (FOOSH) that results in forceful dorsiflexion and impaction of the scaphoid against the dorsal rim of the radius.

This mechanism explains why snuffbox tenderness is so common, even in the absence of a scaphoid fracture.

Conventional medical wisdom dictates that snuffbox tenderness should be equated with a scaphoid fracture unless radiographs prove otherwise.

If initial radiographs do not show fracture, follow-up radiographs should be obtained in 7-14 days, because the fracture line may be more visible after some resorption.

FREQUENCY

Scaphoid fracture has been reported in people aged 10-70 years, although it is most common in young adult men following a fall, athletic injury, or motor vehicle accident.

MORTALITY/MORBIDITY

The scaphoid has no ligamentous or tendinous attachments, but joint compressive forces, trapezial-scaphoid shear stress, and capitolunate rotation moments exert control on the scaphoid.

Therefore, scaphoid fractures have a high incidence of nonunion (8-10%), frequent malunion, and late sequelae of carpal instability and posttraumatic arthritis.

• A higher incidence of aseptic necrosis and nonunion is noted with fractures of the proximal pole of the scaphoid, because no blood vessels enter it.

• A scaphoid fracture can present as a nondisplaced, stable fracture or as a displaced, unstable fracture. Displaced fractures frequently are associated with ligamentous tears in the wrist and require thorough evaluation and follow-up.

SEX

Scaphoid injuries are more common in men than in women.

AGE

Scaphoid fracture is uncommon in children because the physis of the distal radius usually fails first, resulting in Salter type I or II fractures of the distal radius.

Similarly, in elderly patients, the distal radial metaphysis usually fails before the scaphoid can fracture.

CLINICAL

HISTORY

Scaphoid fracture can occur through 2 different mechanisms: a compression injury or a hyperextension (ie, bending) injury.

• The compression injury from a more longitudinal load or impaction of the wrist leads to fracture of the scaphoid without displacement.

• In a hyperextension injury, when tensile stresses generated and applied to the wrist exceed bone strength, a displaced fracture commonly results.

• Other fractures or dislocations of the carpus and forearm occur in 17% of patients.

• In many wrist sprain injuries, the dorsal rim of the radius and the waist of the scaphoid abut, resulting in a contusion of the scaphoid, or even the capsule, with resulting pain that can be provoked by deep palpation in the snuffbox.

PHYSICAL

The patient with a scaphoid fracture often presents complaining of wrist pain and may be diagnosed as having a sprain of the wrist. In sports-related injuries, it is not uncommon for a fractured scaphoid to go unnoticed.

Pain and tenderness are often on the radial side of the wrist. Pain often is exacerbated with wrist motion.

The importance of increasing the number of clinical tests for this injury is vital; one study found that emergency department residents had difficulty naming diagnostic maneuvers beyond "snuffbox tenderness."

• A reliable correlation exists between scaphoid fracture and pain provoked by deep palpation at the volar tubercle of the scaphoid, which is the first bony prominence distal to the volar distal radius.

  • A high positive correlation with scaphoid fracture exists when there is tenderness upon palpation at the snuffbox and volar tubercle.

  • Scaphoid fracture is not very likely when tubercle palpation does not provoke pain in the snuffbox.

• Range of motion (ROM) is reduced, but not dramatically.

• Swelling around the radial and posterior aspects of the wrist is common. If high forces are associated with the injury, ligamentous trauma is also possible.

• These same findings may be present with ligamentous injuries of the wrist; thus, whenever findings are suggestive of a scaphoid fracture, the patient should be treated for a scaphoid fracture.

SPECIAL PROVOCATION MANEUVERS

• Watson (scaphoid shift) test

  • The patient sits with the forearm pronated. The examiner takes the patient's wrist into full ulnar deviation and extension. The examiner presses the patient's thumb with his/her other hand and then begins radial deviation and flexion of the patient's hand.

  • If the scaphoid and lunate are unstable, the dorsal pole of the scaphoid subluxes over the dorsal rim of the radius and the patient complains of pain, indicating a positive test.

• Scaphoid stress test

  • The patient sits while the examiner holds the patient's wrist with one hand, with the examiner applying pressure with his/her thumb over the patient's distal scaphoid. The patient then attempts radial deviation of the wrist.

  • If excessive laxity is present, the scaphoid is forced dorsally out of the scaphoid fossa of the radius with a resulting audible clunk and pain, indicating a positive test.

CAUSES

Scaphoid fractures usually are an injury of young men and women, occurring after a fall, athletic injury, or motor vehicle accident.

DIAGNOSIS

LABORATORY STUDIES

• No laboratory studies are indicated for the diagnosis of scaphoid fracture.

IMAGING STUDIES

• Radiographic examination

  • When a scaphoid fracture is suggested on physical examination, a scaphoid series (including a posteroanterior [PA] view with the wrist in ulnar deviation) should be ordered, because routine wrist anteroposterior (AP), lateral, and oblique views may not show the fracture. Based on retrospective studies and cadaveric review, the most sensitive radiographic evaluation includes 4 views: PA, lateral, pronated oblique (60° pronated oblique), and ulnar deviated oblique (also described as 60° supinated oblique).

  • Comparison views of the contralateral wrist may be necessary. Importantly, as many as 25% of scaphoid fractures are not evident on initial radiographs. Much research has been performed to determine if this conventional wisdom still holds true.

  • If the radiographs are equivocal and it is important for an athlete to return to competition without waiting 7-14 days for repeated radiographs, a bone scan may be obtained after 24 hours, which almost always settles the issue.

OTHER TESTS

• If a diagnosis still cannot be confirmed with confidence on routine films, a technetium-99m (99m Tc) bone scan or a magnetic resonance imaging (MRI) scan of the wrist is recommended, in that order of preference.

• One prospective study found that bone scans performed 3-7 days postinjury are 92% sensitive and 87% specific. Another prospective study found minimal interobserver and intraobserver variability.

• MRI is increasingly used because it offers several distinct advantages; specifically, the modality is noninvasive and readily available, and it can assess bone healing and evaluate for bone contusions and ligamentous injuries.

• A British study looked into the cost effectiveness of MRI and found that the direct cost of the modality did not significantly increase health care costs; additionally, when accounting for productivity losses incurred by unnecessary casting, MRI was found to be much more cost effective. MRI sensitivity and specificity have been reported as 100% and 96.3%, respectively, in the acute setting of suspected scaphoid fracture. Several articles suggest that MRI is a very reasonable next step in cases in which fracture is highly suspected despite initial negative radiographic findings.

• Computed tomography (CT) scanning has very good interobserver and intraobserver reliability, although fractures with less than 1 mm of displacement are often not detected. Its sensitivity and specificity are estimated to be 100% when used 5-10 days postinjury. Bone scanning sensitivity was noted to be 78% in this study.

• High-resolution ultrasonography is also being investigated for the diagnosis of scaphoid fracture, but it relies heavily on the technical skill of the examiner.

• Intrasound vibration examination also has been used to detect the occult, undiagnosed scaphoid fracture.

TREATMENT

PHYSICAL THERAPY

General principles for the rehabilitation of wrist injuries, including the rehabilitation of scaphoid fractures, include the following:

v  All of these injuries require some form of rehabilitation. Specific limitations apply to rehabilitation. Pain is one limiting factor, because it dictates the duration of immobilization and limits exercise designed to mobilize and strengthen the wrist.

v  Edema of the injured wrist is present to some degree and may involve the hand or entire upper extremity. Functional disuse in itself results in edema. The most important preventive measures are elevation and active motion of the uninjured joints. Modalities (eg, Jobst intermittent compression units, massage) may be used later for chronic edema associated with traumatic wrist injuries.

v  The wrist is always stiff after immobilization for more than a few weeks. Mobilization cannot be started until the injured tissue has healed enough to provide some degree of stability. Active wrist ROM exercises should be started as soon as the cast is removed. Pronation and supination should not be overlooked.

v  Mobilizing the joint is desirable before the bone and soft tissues have healed completely. Various splints are required to protect and support the wrist in its final stage of healing.

v  The muscles crossing the wrist must be strengthened after the wrist has healed, edema has been controlled, and motion has improved. Functional activities and progressive resistive exercises are employed. The wrist flexors and extensors are contracted actively against maximum resistance through a full arc of motion.

REHABILITATION CONSIDERATIONS IMMEDIATELY FOLLOWING INJURY TO 1 WEEK

• For casted fractures

  • Active range of motion (AROM) and passive range of motion (PROM) to the digits, except the thumb, which is immobilized

  • AROM and active-assisted range of motion (AAROM) exercises to the shoulder

  • Isometric exercises to the biceps, triceps, and deltoid muscles

• Following open reduction internal fixation (ORIF) surgery

  • Elevation of the arm to treat dependent edema

  • AROM and PROM of digits, except the thumb

  • AROM and AAROM exercises to the elbow and shoulder

  • Isometric exercises to the biceps, triceps, and deltoid muscles

  • Limitation of supination and pronation

REHABILITATION CONSIDERATIONS IN 2 WEEKS

• The clinician may obtain bone or CT scans in the event of continued pain and tenderness over the snuffbox with negative radiographic findings.

• Bone stimulators have been increasingly used for stable, nondisplaced fractures and for suspected scaphoid fractures with negative radiographic findings, although both uses are still somewhat controversial.

• A short-arm cast is indicated for a suspected fracture, while a long-arm cast is used for a known fracture.

• The patient should continue ROM exercises for casted fractures and ORIF, as above.

REHABILITATION CONSIDERATIONS IN 4-6 WEEKS

• For casted fractures

  • Continue exercises as above.

  • Limit supination and pronation.

  • Change the long-arm cast to a short-arm cast (bridging callus indicates stability).

• Following ORIF surgery

  • Advance therapy with gentle AROM of the wrist and gentle opposition and flexion/extension exercises to the thumb.

  • Continue elbow and shoulder exercises.

  • Remove the short-arm cast at 6 weeks if the fracture appears to be radiographically healed.

  • Use a wrist splint for protection.

REHABILITATION CONSIDERATIONS IN 8-12 WEEKS

• For casted fractures

  • Remove the short-arm cast at 10-12 weeks if the fracture appears to be radiographically and clinically healed.

  • A wrist splint may be used for protection

• For casted fractures and following ORIF

  • Consider pulsed electrical stimulation if no evidence of union is noted by 8 weeks, and consider surgery with bone grafting if progress is not observed by 12-14 weeks.

  • Advance therapy with gentle AROM of the wrist and with thumb exercises.

  • Begin grip strengthening with the use of silicone putty at 10 weeks.

  • Advance as tolerated to progressive resistive exercises (PREs).

OCCUPATIONAL THERAPY

The patient usually needs retraining in the performance of activities of daily living (ADL).

The occupational therapist provides the patient with compensatory strategies to use when completing ADL tasks.

Either physical or occupational therapy is necessary for regaining strength and ROM of the affected wrist and hand.

COMPLICATIONS

• Scaphoid injuries and prolonged casting - These result in missed work days and decreased work efficiency.

• Nonunion of scaphoid fracture

  • This complication is influenced by delayed diagnosis, gross displacement, associated injuries of the carpus, and impaired blood supply. Of these fractures, 40% are undiagnosed at the time of original injury.

  • Nonunion is 20% more common in smokers.

  • The incidence of avascular necrosis is approximately 30-40%, occurring most frequently in fractures of the proximal third.

  • Scapholunate disassociation is a well-known complication of scaphoid fracture.

SURGICAL INTERVENTION

• Displaced or unstable fractures require percutaneous pin fixation or compression screw fixation to prevent malunion. Internal fixation is accomplished with either smooth Kirschner wires or a Herbert screw.

• Surgery is increasingly used for patients (especially athletes) who will not tolerate prolonged casting.

• Nonunions of the scaphoid are treated in one of the following ways:

  • Radial styloidectomy

  • Excision of the proximal fragment

  • Proximal row carpectomy

  • Traditional bone grafting

  • Total or partial arthrodesis of the wrist

• Because of the significant time required for the union of proximal pole fractures, some surgeons recommend primary fixation of these fractures even when they are not displaced.

• The Matti-Russe procedure involves treatment of nondisplaced fractures by excavation of the scaphoid and placement of a volar corticocancellous bone graft.

• If the proximal pole is avascular and no significant radiocarpal arthritis is present, revascularization of the scaphoid bone with a vascularized bone graft from the radius may be attempted. A review of more than 5000 cases found that vascularized bone grafting (with or without internal fixation) was 91% successful, that nonvascularized bone grafting with internal fixation was 84% successful, and that nonvascularized bone grafting without internal fixation was 80% successful.

• A silicone carpal implant is no longer recommended.

• Once degenerative arthritis is evident at the radiocarpal joint, salvage procedures include proximal row carpectomy, scaphoid excision, and intercarpal or total wrist arthrodesis.

OTHER TREATMENT

• Non-displaced fractures

  • Initially, nondisplaced fractures are treated with a long-arm thumb spica cast with the wrist in neutral position for 6 weeks, followed by a short-arm spica cast for an additional 6 weeks, until roentgenographic union is evident. If there is a displacement or widening of the fracture line after 6 weeks, the patient should be referred for surgical evaluation.

  • After immobilization, active ROM exercises to the forearm, wrist, and thumb should be performed 6-8 times daily.

  • A wrist-and-thumb static splint with the wrist in neutral should be worn between exercise sessions and at night.

• Displaced fractures

  • These usually require ORIF using wires and screws.

  • Then, a short-arm thumb spica is needed for 8-12 weeks until roentgenographic union is evident.

  • At 4 months after surgery, dynamic wrist flexion and extension may be initiated.

  • At 6 months, the patient usually resumes normal use of his/her hand.

• Electrical stimulation, or pulsed electromagnetic stimulation, has been proposed as beneficial in cases of non-displaced scaphoid nonunion; however, this technique remains controversial, because no study has been conducted to compare the results of employing PES alone with those of using only cast immobilization.

MEDICATION

Drugs used for pain management include analgesics. The agents used for mild to moderate pain, such as aspirin, acetaminophen, and nonsteroidal anti-inflammatory drugs (NSAIDs), are nonopioids.

These agents usually suffice; if they do not, however, the clinician can prescribe opiate agonists, such as codeine or propoxyphene.

ANALGESICS

Effective management of pain is essential to quality patient care. Pain management improves the patient's quality of life, as well as his/her ability to work productively and to participate in self-care and physical therapy activities. 

ACETAMINOPHEN (Tylenol, Panadol, Tempra)

Effective in relieving mild to moderate acute pain; however, acetaminophen has no peripheral anti-inflammatory effects. It may be preferred in elderly patients because of fewer GI and renal side effects.

Adult: 325-650 mg PO q4-6h prn; alternatively, 1000 mg PO tid/qid; not to exceed 4 g/d; daily dose not to exceed 6 extended-release tab

Pediatric: 10-15 mg/kg PO or PR q4-6h; not to exceed 5 doses in 24 h

Extended-release dose not established for this population

Pregnancy

A - Fetal risk not revealed in controlled studies in humans

Precautions

Hepatotoxicity possible in chronic alcoholics following various dose levels; severe or recurrent pain or high or continued fever may indicate a serious illness; APAP is contained in many OTC products and combined use with these products may result in cumulative APAP doses exceeding recommended maximum dose 

TRAMADOL (Ultram)

Synthetic analog of codeine; however, tramadol has a lower affinity for opioid receptors than does codeine. It has less potential for abuse or respiratory depression than do other opiate agonists, but both may occur.

Tramadol is equivalent in analgesic relief to codeine, but it is less potent than are acetaminophen-codeine and acetaminophen-hydrocodone combinations. A lack of significant cardiac effects and no association with peptic ulcer disease make tramadol an alternative in patients who may not tolerate NSAIDs.

Adult: 50-100 mg PO q4-6h; not to exceed 400 mg/d

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Can cause dizziness, nausea, constipation, sweating, pruritus; additive sedation with alcohol and TCAs; abrupt discontinuation can precipitate opioid withdrawal symptoms; adjust dose in liver disease, myxedema, hypothyroidism, hypoadrenalism; pregnancy, breastfeeding; seizure; development of tolerance or dependency with extended use 

PROPOXYPHENE AND ACETAMINOPHEN (Darvocet N-100)

Used to treat moderate to severe pain. The combination produces additive analgesia compared with the same doses of either agent alone; however, dosage escalation of this combination is limited by the side effects of propoxyphene and by the toxicity and ceiling effect of acetaminophen.

Adult: 1 tab PO q4-6h prn; not to exceed propoxyphene 600 mg/d and acetaminophen 4000 mg/d (6 tab)

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Caution in patients dependent on opiates, substitution may result in acute opiate withdrawal symptoms; caution in severe renal or hepatic dysfunction 

ACETAMINOPHEN AND CODEINE (Tylenol #3)

Used to treat moderate to severe pain. Tylenol #3 produces additive analgesia compared with the same doses of either agent alone. Dosage escalation of this combination is limited by the ceiling effect of acetaminophen.

Adult: 30-60 mg based on codeine content PO q4-6h or 1-2 tab q4h; not to exceed 12 tab/d

Pediatric: 1-1.5 mg/kg/d codeine PO q4-6h prn; not to exceed 75 mg/kg/d of acetaminophen 

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Caution in patients with COPD or decreased pulmonary reserve; renal and hepatic dysfunction; abrupt discontinuation can result in withdrawal symptoms; patients with asthma who also have salicylate hypersensitivity

CYCLOOXYGENASE-2 (COX-2) INHIBITORS

Although increased cost can be a negative factor, the incidence of costly and potentially fatal GI bleeds is clearly less with COX-2 inhibitors than with traditional NSAIDs. Ongoing analysis of cost avoidance of GI bleeds will further define the populations that will find COX-2 inhibitors the most beneficial. 

CELECOXIB (Celebrex)

Inhibits primarily COX-2. COX-2 is considered an inducible isoenzyme, induced during pain and inflammatory stimuli. Inhibition of COX-1 may contribute to NSAID GI toxicity. At therapeutic concentrations, COX-1 isoenzyme is not inhibited; thus, GI toxicity may be decreased. Seek the lowest dose of celecoxib for each patient.

Adult: 200 mg PO qd or 100 mg PO bid

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

May cause fluid retention and peripheral edema; caution in compromised cardiac function, hypertension, conditions predisposing to fluid retention; severe heart failure and hyponatremia, because may deteriorate circulatory hemodynamics; NSAIDs may mask usual signs of infection; caution in the presence of existing controlled infections; evaluate symptoms and signs suggesting liver dysfunction, or in abnormal liver lab results

NONSTEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS)

Have analgesic, anti-inflammatory, and antipyretic activities. Their mechanism of action is not known, but they may inhibit COX activity and prostaglandin synthesis.

Other mechanisms may exist as well, such as the inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell-membrane functions. 

KETOPROFEN (Orudis, Actron, Oruvail)

For relief of mild to moderate pain and inflammation.

Small dosages initially are indicated in small and elderly patients and in those with renal or liver disease.

Doses over 75 mg do not increase the therapeutic effects. Administer high doses with caution and closely observe the patient for a response.

Adult: 25-50 mg PO q6-8h prn; not to exceed 300 mg/d

Pediatric:

<3 months: Not established

3 months to 12 years: 0.1-1 mg/kg PO q6-8h

>12 years: Administer as in adults

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

Caution in congestive heart failure, hypertension, and decreased renal and hepatic function; caution in anticoagulation abnormalities or during anticoagulant therapy 

NAPROXEN (Naprelan, Anaprox, Naprosyn)

For relief of mild to moderate pain; naproxen inhibits inflammatory reactions and pain by decreasing the activity of COX, which results in a decrease in prostaglandin synthesis.

Adult: 500 mg PO followed by 250 mg q6-8h; not to exceed 1.25 g/d

Pediatric:

<2 years: Not established

>2 years: 2.5 mg/kg/dose PO; not to exceed 10 mg/kg/d

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

Acute renal insufficiency, interstitial nephritis, hyperkalemia, hyponatremia, and renal papillary necrosis may occur; patients with preexisting renal disease or compromised renal perfusion risk acute renal failure; leukopenia occurs rarely, is transient, and usually returns to normal during therapy; persistent leukopenia, granulocytopenia, or thrombocytopenia warrants further evaluation and may require discontinuation of drug 

IBUPROFEN (Motrin, Advil, Nuprin, Rufin)

Oral NSAID with analgesic and antipyretic properties. Ibuprofen is useful for the alleviation of mild to moderate pain.

Adult: 400-800 mg PO tid/qid; not to exceed 3200 mg/d; use lowest effective dose

Pediatric: 30-40 mg/kg PO tid/qid in divided doses; not to exceed 50 mg/kg/d.