Chapter 3 – Wrist




Chapter 3 Wrist



Christopher R. Pruitt



Background




  • The wrist represents the region from the distal radius and ulna to the carpometacarpal joints.



  • It is one of the most complex and dynamic joints in the human body, and yet also one of the most commonly injured regions.



  • Spectrum of disease varies greatly, ranging from simple sprains to complex fracture/dislocation patterns with associated neurologic compromise.



  • This provides for a vast array of potential pathology, making the evaluation and diagnosis of injury quite difficult.



  • Making things even more complex, even subtle injury patterns can have dramatic and longstanding complications if not properly diagnosed and treated at initial presentation.



  • Consequences from injury and delay in diagnosis include:1




    • Rising medical costs



    • Decreased school attendance



    • Lost work hours



    • Loss of independence



    • Chronic pain



    • Lasting functional disability



  • A thorough knowledge of anatomy, mechanism of injury, injury patterns, radiographic findings, and appropriate treatment and follow-up are imperative for optimal patient care.



Epidemiology




  • Wrist injuries are one of the most common presentations in the ED, accounting for 2.5% of all ED visits.2



  • Incidence appears to be increasing worldwide, likely multifactorial:3




    • Advancing age and changes in bone metabolism



    • Increasing sports activity in children



    • Increasing obesity rates



  • The most common fracture is the distal radius fracture, which accounts for one-sixth of all fractures seen and treated in US emergency departments.4




    • Colles fracture is the most common fracture in all persons less than 75 years old



  • Carpal fractures account for 20% of fractures to wrist and hand.5



  • Injury patterns tend to be bimodal in distribution, affecting youth and elderly populations primarily.




    • Younger patients tend to present with higher mechanism injuries.




      • Motor vehicle accidents



      • Sports injuries



    • Elderly patients present after low mechanism falls.



  • The vast majority of wrist pathology occurs via a fall on outstretched hand (FOOSH) (fall on an outstretched hand) mechanism.



Anatomic Considerations / Pathophysiology




  • The wrist is composed of the distal radius and ulna, as well as eight carpal bones that are arranged in two transverse rows (Figure 3.1).




    • Proximal carpal row (radial to ulnar) – scaphoid, lunate, triquetrum, pisiform.



    • Distal carpal row (radial to ulnar) – trapezium, trapezoid, capitate, hamate.



    • The carpal rows form three “arcs,” which are key to identifying injury on PA radiograph.




      • Proximal border of the scaphoid, lunate, and triquetrum



      • Distal border of the proximal carpal row



      • Proximal border of the capitate and hamate



      • These arcs should be smooth and continuous



      • Each of the carpal bones is separated by a uniform 1–2 mm.



  • Principle movements of the wrist are flexion, extension, radial deviation, and ulnar deviation.



  • The radius articulates directly with the proximal carpal row.




    • Articular surface is both concave and tilted.




      • Concavity “cups” the scaphoid and lunate



      • Normal volar tilt of 0–22° (lateral radiograph)



      • Normal radial tilt (“or radial inclination”) of 15–30° (PA radiograph)



  • The ulna has no direct bony articulations.




    • Ulna has a nonosseous fibrocartilage union with the radius, triquetrum, and lunate, called the triangular fibrocartilage complex (TFCC). (Figure 3.2)



  • The ulna articulates with the radius at the distal radioulnar joint (DRUJ).




    • Stability of this joint is maintained by the TFCC, interosseous membrane, and both dorsal and volar radioulnar ligaments.



    • Pronation and supination are accomplished through articulations at the proximal and distal radioulnar joints.



  • There are two classifications of ligaments in the wrist: extrinsic and intrinsic.




    • Extrinsic ligaments connect carpal bones to the radius, ulna, or metacarpals.



    • Intrinsic ligaments connect carpal bones to one another.



  • Extrinsic ligaments are further characterized as dorsal or volar.




    • Volar ligaments are relatively stronger than dorsal counterparts, which plays a role in injury pattern and associated carpal instability.



  • There is dual vascular supply to the wrist with the radial and ulnar arteries.




    • Radial artery runs lateral (radial) to the flexor carpi radialis.



    • Ulnar artery is just radial to the flexor carpi ulnaris.



  • Many of the carpal bones have solitary vascular supply, paradoxically running in a distal to proximal course. This has significant impact on fracture healing, depending on anatomic location of the lesion, which is described later in more detail.



  • Motor and sensory inputs are from radial, ulnar, and median nerves:




    • Radial nerve courses dorsally, supplying motor function to wrist extension and finger extension; sensory input is to the dorsum of the hand.



    • Median nerve runs within the carpal tunnel on the volar aspect of the wrist, supplying motor function to wrist flexion, finger flexion, thumb flexion, extension, and abduction; sensory input is to the volar aspect of the hand for the first three digits.



    • Ulnar nerve runs parallel to the ulnar artery and passes through Guyon’s canal, consisting of the pisiform and hook of the hamate; it controls hypothenar muscles, interossei, and the fourth and fifth digit lumbricals; sensory input is to the ulnar side of the palm and fourth and fifth digits.



  • Each of these nerves is susceptible to injury with certain fracture patterns, to be discussed later in the chapter.





Figure 3.1. PA view of the carpal bones. S = Scaphoid, L = Lunate, T = Triquetrum, P = PisiformTr = Trapezium, Td = Trapezoid, C = Capitate, H = Hamate.





Figure 3.2. Triangular Fibrocartilage Complex (TFCC).


Illustration by Yvonne Chow.


Focused History and Physical Examination



History




  • As with any medical presentation, a good history is paramount.



  • Key features include:




    • Mechanism of injury



    • Timing and duration or pain



    • Alleviating and aggravating features



    • Neurovascular changes



    • History of prior injury or surgery



    • Baseline motor and sensory function prior to injury



    • Hand dominance



    • Special attention to baseline activity and occupation



Physical Examination




  • Physical examination begins with appearance and comparison to the opposite extremity.




    • Note swelling, ecchymosis, deformity, and distal perfusion



    • Point of maximal tenderness, referred pain



    • Passive and active ROM, noting pain and limitations



  • Palpable landmarks:




    • Dorsal (radial to ulnar) (Figure 3.3):




      • Radial Styloid




        • Distal end of the radius, easily palpable and usually visible on inspection



      • Snuff box (Figure 3.4)




        • Bordered proximally by the radial styloid, radially by the abductor pollicis longus and extensor pollicis brevis, and ulnarly by the extensor pollicis longus tendon



        • Scaphoid resides within the snuff box, more prominent with ulnar deviation



      • Lister’s tubercle




        • Depression felt just ulnar to the radial styloid



        • Landmark for the scapholunate joint



        • Capitate is palpated just distal with the wrist in neutral position



        • Lunate is palpable with the wrist in flexion



      • Ulnar styloid




        • Bony prominence on the dorsal ulnar aspect, easily visible



      • Triquetrum




        • Palpable just distal to the ulnar styloid



    • Volar (radial to ulnar)(Figure 3.5):




      • Scaphoid Tubercle




        • Just distal to the radial styloid, at the thenar muscle base



      • Pisiform




        • At the base of the hypothenar muscles, just distal to the ulnar styloid and distal wrist crease



      • Hook of the hamate




        • Approximately 1 cm distal and radial to the pisiform



  • Range of motion:




    • Test range of motion of the wrist in all directions and compare to the contralateral side.



    • Range of motion at the wrist includes:




      • Flexion



      • Extension



      • Pronation



      • Supination



      • Radial deviation



      • Ulnar deviation



  • Special tests:




    • Finkelstein test (De Quervain’s tenosynovitis) (Figure 3.6)




      • Patient places the thumb in flexion within the palm, and examiner deviates the wrist ulnarly.



      • Positive = pain



    • Tinel’s sign (carpal tunnel syndrome) (Figure 3.7)




      • Tapping the volar wrist over the carpal tunnel



      • Positive = paresthesias in median nerve distribution



    • Phalen’s test (carpal tunnel syndrome) (Figure 3.8)




      • Dorsiflexion of the wrist for upwards of 60 seconds



      • Positive = paresthesias in median nerve distribution



    • Scaphoid shift test (scapholunate dissociation) (Figure 3.9)




      • Examiner’s thumb presses on the base of the thenar eminence, over the scaphoid, while the hand wraps around the wrist.



      • Examiner’s opposite hand holds the patient’s hand at the level of the MCP joints.



      • The wrist is held in extension and mild ulnar deviation.



      • While applying thumb pressure over the scaphoid, the wrist is gently flexed and radially deviated.



      • Positive = if the scaphoid shifts dorsally



      • While releasing pressure on the scaphoid, examiner or patient may feel or hear a “click” as the scaphoid returns to its normal position.



    • TFCC compression test (TFCC tear) (Figure 3.10)




      • Axial load the wrist and then deviate wrist to ulnar side.



      • Test is positive if it creates a click and reproduces the patient’s pain.



    • Piano key test




      • Assesses the stability of the DRUJ.



      • With the wrist in pronation, volar pressure is placed on the distal ulna.



      • Test is positive if pain or instability is elicited compared to contralateral side.



    • Shuck test (Figure 3.11)




      • Also tests stability of DRUJ



      • The distal radius is held with one hand, and the distal ulna with the other.



      • The distal radius is moved dorsally.



      • This test is positive if it elicits pain or instability compared to the contralateral side.



  • Neurovascular exam:




    • Two-point discrimination is the most sensitive test for sensory function of the nerves.



    • Compare to uninjured hand




      • Volar




        • Distinguish two blunt points that are 2–5 mm apart on the fingertips, 7–10 mm at the base of the palm6



      • Dorsal




        • Distinguish two blunt points at 7–12 mm



    • Median nerve




      • Sensory – sensation to the index fingertip



      • Motor – thumb abduction



    • Ulnar nerve




      • Sensory – sensation to little fingertip



      • Motor – abduction of fingers, or thumb adduction



    • Radial nerve




      • Sensory – sensation to dorsum of thumb/webspace



      • Motor – extension of wrist and MCPs



  • Vascular exam:




    • Radial pulse



    • Ulnar pulse



    • Capillary refill





Figure 3.3. Dorsal landmarks of the wrist.





Figure 3.4. Anatomic snuff box landmarks. The radial styloid forms the base, and both the scaphoid and trapezium may be palpated within the snuff box.





Figure 3.5. Volar landmarks of the wrist.





Figure 3.6. Finkelstein test.





Figure 3.7. Tinel’s sign.





Figure 3.8. Phalen’s test.





Figure 3.9. Scaphoid shift test.





Figure 3.10. Triangular fibrocartilage complex (TFCC) compression test.





Figure 3.11. Shuck test.



Radiographic Considerations




  • Evaluation begins with PA, lateral, and oblique radiographs of the wrist.




    • PA radiograph provides detailed information for both obvious and subtle injury patterns (Figure 3.12).




      • Radial length (height) – measurement from the ulnar articular surface to the tip of the radial styloid




        • Normal is 9–12 mm



        • Shortening is suggestive of distal radial fracture



      • Radial tilt (inclination) – measurement of ulnar slant of the radial articular surface




        • Normal is 15–30°



        • Decrease is suggestive of fracture or DRUJ disruption



      • Carpal arcs (Figure 3.13)– three smooth lines drawn between carpal bones




        • Proximal – proximal border of scaphoid, lunate and triquetrum



        • Middle – distal border of proximal carpal row



        • Distal – proximal border of capitate and hamate



        • Disruption of these lines is suggestive of fracture, dislocation, or both



      • Carpal distance – the space between each of the carpal bones




        • Normal is 1–2 mm, equal distance between each bone



        • Pathologic is greater than 3 mm



    • Lateral radiograph evaluates the fracture line, volar or dorsal displacement, intra-articular extension, and carpal alignment.




      • Lateral radiograph should have no more than 2 mm of the ulna projecting beyond the radius



      • Pronator quadratus fat pad – normal radiolucent linear line just volar to the radius and ulna




        • Volar displacement, bowing, or loss of fat pad suggests radius or ulna fracture



      • Volar tilt of radius (Figure 3.14) – the natural angle of the radiocarpal joint




        • Normal is 0–22° volar angulation



        • Measured by the angle formed by a line perpendicular to the long axis of the radius and a line along the surface of the distal radius



        • Fractures with dorsal angulation need to be reduced to neutral or + volar tilt for good functional outcome



      • Straight line should exist between central axis of the radius, lunate, capitate and the third metacarpal. (Figure 3.15)




        • Normal variance up to 10°



        • Disruption is suggestive of fracture or carpal dislocation



      • Scapholunate angle (Figure 3.16) – angulation between intersecting lines drawn through the central axis of the scaphoid and lunate




        • Normal is 30–60°



        • Angulation greater than this suggests rotary subluxation of the scaphoid, or fracture



      • Capitolunate angle – angulation between central axis lines through capitate and lunate




        • Normal is 0–30°



        • Greater than 30° suggests carpal dislocation



    • Oblique radiograph is best for assessing the most radial carpal bones.




      • Scaphoid, trapezoid, trapezium more clearly seen in this view compared to the PA



      • Also helpful for assessing intra-articular extension of distal radius fractures



  • Dedicated views may be obtained with suspicion for certain injuries.




    • Scaphoid view – PA radiograph with the wrist held in ulnar deviation




      • Exposes the scaphoid



      • Enhances detection of subtle fractures



    • Carpal tunnel view – wrist is held in hyperextension, radiograph is directed across the volar wrist.




      • Good for detection of hamate and pisiform fractures



    • Clenched fist view – AP radiograph with patient clenching the fist forcefully




      • Accentuates potential scapholunate dissociation





Figure 3.12. Normal radial length and inclination on PA radiograph.





Figure 3.13. Carpal arcs on PA view.





Figure 3.14. Normal volar tilt on lateral radiograph.





Figure 3.15. Straight line through radius, lunate, capitate, and metacarpal.





Figure 3.16. Normal scapholunate angle.



Differential Diagnosis-Emergent and Common Diagnoses



Scaphoid Fractures



General Description



  • Most common fractured carpal bone, accounting for 62–87% of all carpal fractures7



  • Scaphoid serves as a link between the carpal rows.




    • Bulk of it is articular surface



    • Acts to stabilize the carpal rows



  • Also one of the most frequently missed carpal fractures




    • Misdiagnosed as “wrist sprain”



    • Delay in diagnosis increases chance for poor outcome



  • High incidence of AVN and nonunion due to poor vascular supply




    • Blood enters the dorsal cortex near the tubercle waist



    • Proximal bone has no direct blood supply



  • Fractures are characterized by anatomic location:




    • Proximal pole – 10–20%



    • Scaphoid waist – vast majority at 70–80%8



    • Distal pole – majority are pediatric9



    • Tubercle




Table 3.1 Emergent and Common Diagnoses in the Emergency Department




























Emergent Diagnoses Common Diagnoses
Perilunate dislocation Scaphoid fracture

Lunate dislocation Distal radius fracture
Displaced distal radius fracture Carpal tunnel syndrome
Any open fracture De Quevain’s tenosynovitis
Any injury associated with neurovascular compromise Ganglion cyst
Any unstable fracture or dislocation


Mechanism



  • Injury occurs with forced hyperextension and axial load of the wrist, described as FOOSH



  • Radial deviation impinges the scaphoid against the radius



  • Approximately 3% occur with flexion injury10



Presentation



  • Typically seen in young adults, age 15–30




    • Rare in children, as the carpus is primarily cartilaginous until adolescent years



  • Dorsal wrist pain just distal to the radial styloid



  • Complaint of pain with wrist and thumb movement



  • Swelling and ecchymosis is variable



Physical Examination



  • Overall excellent sensitivity, but poor specificity at 74–80%




    • Tenderness directly over the scaphoid, both volar and dorsal



    • Tenderness in anatomic snuff box – 90% sensitive, 40% specific



    • Axial load of thumb in line with first metacarpal



    • Resisted supination



    • Flexion and radial deviation



Essential Diagnostics



  • Standard PA, oblique, and lateral x-ray views will pick up many fractures (Figures 3.17 and 3.18).




    • Look for displaced scaphoid fat stripe as subtle finding11



  • If the exam is suggestive of injury, a scaphoid view increases sensitivity.



  • Despite this, upwards of 30% of fractures will be undetectable in the acute setting.12



  • CT scan is very sensitive for fracture, but cases of false negatives have been reported.



  • Wrist MRI has been reported as 100% sensitive in multiple studies, but is not readily available in most EDs.





Figure 3.17. Displaced and angulated scaphoid fracture.





Figure 3.18. Abnormal fat pad in subtle scaphoid fracture.



ED Treatment and Disposition



  • Based on suspicion for injury and x-ray findings



Clinically Suspected Injury, XR Normal



  • Splint in short arm thumb spica



  • Re-examine in seven to ten days, repeat x-ray




    • If negative but continued clinical suspicion, reapply splint and re-evaluate again in seven to ten days, consider bone scan, CT, or MRI



    • If positive for nondisplaced fracture, thumb spica cast for six weeks



Nondisplaced Scaphoid Fracture



  • Thumb spica splint in the ED




    • Debate over long vs. short arm splints, no clear correct answer



  • Follow-up with thumb spica casting




    • Period of immobilization varies depending on anatomic location of fracture; more proximal fracture = longer



    • Average immobilization is twelve weeks



Displaced Scaphoid Fracture



  • Thumb spica splint in the ED



  • Significant displacement, comminution, and/or angulation require hand surgeon consultation and urgent referral




    • Such injuries require open reduction and internal fixation



    • Absolute indications: ≥1-mm displacement, ≥ 15-mm angulation



Return to Play



  • Most athletes will undergo surgical fixation to allow for earlier return to athletic activity.




    • If screw fixation with satisfactory union is achieved, patients may begin athletics within a few weeks while remaining in cast with appropriate paddling



  • After the cast has been removed, early ROM and strengthening with physical therapy are essential to restore function.



  • The wrist should remain in rigid bracing with activity until:




    • Radiographic evidence of union



    • Strength and ROM are similar to the uninjured extremity



    • Pain subsides



Complications



  • Given the tenuous blood supply, scaphoid fractures have a high rate of nonunion and avascular necrosis (AVN).




    • Incidence of AVN 13–40%13, 14



    • Nonunion rates vary according to injury pattern and treatment:




      • Displaced fractures, 50% rate of nonunion



      • Nondisplaced and immobilized, 15% nonunion rate15



      • Proximal > waist > distal > tubercle



  • Delayed union and nonunion are directly related to premature discontinuation of immobilization.



  • There is a high incidence of chronic pain and radiocarpal arthritis.



Pediatric Considerations



  • Low likelihood of carpal injury until adolescence



  • High incidence in teenage athletes



Pearls and Pitfalls



  • 90% of scaphoid injuries occur in isolation.



  • If there is suggestion of injury on examination, treat as such despite normal x-rays.




    • Up to 30% of initial x-rays read as normal



    • Place in thumb spica and arrange for follow-up within one week



  • Hesitate to diagnose “wrist sprain,” truly a diagnosis of exclusion.



  • Any injury to the proximal scaphoid warrants consultation, as some surgeons will elect for operative stabilization vs. conservative therapy.



Triquetrum Fractures



General Description



  • Second most common carpal fracture



  • Two general types:




    • Dorsal chip – most common



    • Triquetral body



  • Excellent vascular supply, thus low risk for AVN and nonunion



Mechanism



  • Dorsal chip – typical mechanism with FOOSH, in ulnar deviation




    • Hamate forces triquetrum against radius or ulnar styloid



  • Body – direct impact on dorsal hand, usually high mechanism




    • Association with perilunate dislocations



Presentation



  • Variable presentation




    • Possible pain, swelling, and ecchymosis on dorsum of the hand



Physical Examination



  • Tenderness and edema to the dorsum of the hand, just distal to the ulnar styloid



  • Limited ROM with both flexion and extension



Essential Diagnostics



  • Dorsal chip – best seen on lateral radiograph



  • Body – standard PA or oblique views





Figure 3.19. Dorsal chip fracture of the triquetrum.



ED Treatment and Disposition



  • Treat with volar splint in the ED, followed by short arm cast.



  • Four to six weeks usually results in complete healing.



Return to Play



  • Athletes can return to sports while casted provided that there is adequate padding.



  • After cast removal, athletes should remain in a semi-rigid brace until there is no further tenderness.



Complications



  • Rarely ulnar nerve injury



  • Limited AVN due to good vascular supply



Pediatric Considerations



  • None



Pearls and Pitfalls



  • In patients with perilunate fracture/dislocation, make sure to search for triquetral body fractures.



Lunate Fractures




General Description



  • Account for 1.4–6% of carpal fractures16, 17



  • Lunate lies between the radius and the distal capitate



  • Two general fracture patterns:




    • Dorsal avulsion



    • Lunate body



  • Like the scaphoid, vascular supply runs distal to proximal and predisposes the lunate to AVN



  • Posttraumatic AVN, referred to as Keinbock’s disease, results from approximately 20% of lunate fractures



Mechanism



  • Dorsal avulsion fractures usually result from forced hyperextension, FOOSH



  • Lunate body fractures typically occur from axial loading



Presentation



  • Pain and swelling on the dorsum of the hand



Physical Examination



  • Tenderness on the dorsum of the hand, just distal to Lister’s tubercle



  • Exacerbated by axial load on the third metacarpal



Essential Diagnostics



  • Standard PA, oblique, and lateral radiographs frequently miss nondisplaced lunate fractures.



  • Cone-down views may enhance sensitivity, but still frequently miss fractures.



  • CT and MRI both offer excellent sensitivity, and may be obtained in follow-up for those with high suspicion.



ED Treatment and Disposition



  • Immobilize in thumb spica splint.



  • Refer to hand surgeon for casting for roughly six to eight weeks.



  • Fractures with displacement of more than 1 mm, angulation, or instability warrant urgent orthopedic referral for operative intervention.



Return to Play



  • Aggressive rehabilitation with ROM and strengthening should be pursued after cast removal.



  • Rigid bracing should be employed until strength and ROM are similar to the uninjured side, typically at least three months.



Complications



  • Much like the scaphoid, lunate fractures are prone to AVN and nonunion due to poor vascular supply, especially with proximal injury.



Pediatric Considerations



  • Lunate fractures generally fair better in adolescents when compared to adults.



Pearls and Pitfalls



  • Even if x-rays are negative, if clinical suspicion is high for injury, splint the patient and refer to hand surgeon for follow-up and x-rays in seven to ten days.



  • Isolated lunate fractures are uncommon, necessitating a search for associated distal radius, carpal, or metacarpal injuries.



Capitate Fractures



General Description



  • Largest of the carpal bones



  • Centrally located in the distal carpal row




    • Articulations with proximal scaphoid and lunate, adjacent trapezoid and hamate, and the three middle metacarpals



  • Given location, rarely fractured




    • Isolated fractures occur in less than 0.3% of all carpal injuries18



    • Frequently associated with scaphoid fracture and perilunate dislocation



    • Fractures are usually transverse in nature



Mechanism



  • Two general mechanisms:




    • FOOSH, forced hyperextension



    • Direct blow to dorsum of the hand



Presentation



  • Pain and swelling to the dorsum of the hand



Physical Examination



  • Direct palpation on the dorsum of the hand, over the capitate, reproduces the greatest pain.



  • Pain with axial loading of the third metacarpal



  • Swelling and ecchymosis to the dorsum of the hand



  • Rarely may have associated median neuropathy.



Essential Diagnostics



  • Standard PA, lateral, and oblique views usually identify fracture



  • If x-ray is negative and high clinical suspicion, CT is very sensitive.



ED Treatment and Disposition



  • Nondisplaced fractures




    • Immobilization in thumb spica splint



    • Follow-up thumb spica or short arm casting for six to eight weeks



  • Displaced or associated carpal instability




    • Splint and urgent hand surgeon referral for operative intervention



Return to Play



  • Nonsurgical fractures may return to play once casted.



  • Surgical fractures may not return to play while still in cast for approximately four to six weeks.




    • Selective return to play with protective splinting for next three months.



    • May return to play without protective splinting once full range of motion, strength, and function have been restored.



Complications



  • Like scaphoid fractures, associated with AVN and nonunion, especially if proximal fracture



  • High incidence of perilunate ligamentous injury and dislocation



  • Median neuropathy or acute carpal tunnel syndrome



Pediatric Considerations



  • Rare



Pearls and Pitfalls



  • Capitate fractures rarely occur in isolation. If found, it is imperative to search for associated pathology.




    • Distal radius and scaphoid fracture



    • Perilunate instability



  • Err on the side of caution and splint if there is clinical concern for fracture.



Hamate Fractures



General Description



  • Most ulnar of the distal carpal bones



  • Fractures are uncommon, accounting for 1–4% of carpal fractures



  • Three general types:




    • Hook (or hamulus) – most common



    • Body or proximal articular surface



    • Distal articular surface



Mechanism



  • Overlapping mechanisms with the different fracture patterns:




    • Hook




      • Direct impact on the palmar surface, usually from repetitive vibratory forces (hammer, racquet sports)



      • FOOSH



    • Body




      • High impact direct force or axial load



      • FOOSH



    • Distal articular surface




      • Direct blow or axial load on the fifth metacarpal



Presentation



  • Pain and swelling to the hypothenar eminence



  • Paresthesias in the ulnar distribution



Physical Examination



  • Tenderness over the hamate, approximately 1 cm distal and radial to the pisiform



  • Proximal injuries exhibit pain with wrist ROM



  • Distal injuries with pain on axial load of the fifth metacarpal



  • Assess for ulnar neuropathy



Essential Diagnostics



  • PA, oblique, and lateral views will likely pick up significant body fractures (Figure 3.20), but frequently miss factures of the hook.



  • Carpal tunnel views (Figure 3.21) and reverse oblique radiographs are best for hook fractures.



  • If mechanism and exam are consistent with injury, CT can be obtained and is reportedly 100% sensitive.19





Figure 3.20. Hamate fracture on oblique radiograph.





Figure 3.21. Hook of hamate on carpal tunnel view P = Pisiform, H = Hamate.



ED Treatment and Disposition



  • Immobilize in ulnar gutter splint



  • Nondisplaced fractures managed with routine follow-up in seven to ten days for casting for total of six to eight weeks.



  • Displaced fractures or ulnar neuropathy: urgent follow-up and likely operative intervention



Return to Play



  • Nondisplaced body fractures may return to sport immediately with semi-rigid synthetic cast.



  • After operative repair, may return to sport approximately four to six weeks after function is restored.



Complications



  • Ulnar neuropathy and nonunion is common with Hook fractures.




    • Usually require operative excision of the hook



  • Ulnar artery injury can also occur, as it courses alongside the nerve



  • Fifth MCP arthritis



Pediatric Considerations



  • Rare in children.



Pearls and Pitfalls



  • Pain in the hypothenar region and history of repetitive vibratory force (hammer, racket sports) should prompt search for hamate injury.




    • Obtain carpal tunnel view to search for fracture



  • Ulnar neuropathy is common in hamate hook fractures.



Pisiform Fractures



General Description



  • Unique as the only carpal sesamoid bone



  • Only articulation is with the triquetrum.



  • Flexor carpi ulnaris attaches to the volar aspect of the pisiform.



  • Forms part of Guyon’s canal (with hamulus) through which both ulnar artery and nerve pass



  • Fractures are rare, generally carry a good prognosis




    • Avulsion



    • Transverse body



    • Comminuted



Mechanism



  • Two general injury patterns




    • FOOSH or forced hyperextension



    • Direct blow to hypothenar eminence



  • Avulsion fractures result from hyperextension/traction on flexor carpi ulnaris



Presentation



  • Pain and swelling to the hypothenar region



  • Ulnar paresthesias



  • Complaint of hand weakness



Physical Examination



  • Pain and swelling over the pisiform, exacerbated by wrist flexion and ulnar deviation.



  • Assess for possible ulnar neuropathy



Essential Diagnostics



  • Standard PA radiograph will sometimes demonstrate fracture.



  • Reverse oblique and carpal tunnel views are far more sensitive.16



ED Treatment and Disposition



  • Immobilization in volar splint



  • Routine follow-up in one week with casting for total of four to six weeks



  • Cases of ulnar neuropathy require urgent consultation



  • Nonunion could necessitate operative excision



Return to Play



  • May return to sport once casted as long as pain free



Complications



  • Ulnar neuropathy as detailed earlier



  • Flexor carpi ulnaris injury



  • Nonunion, although rare



Pediatric Considerations



  • As with other carpal injuries, pisiform fracture is rare in young children



Pearls and Pitfalls



  • Ensure complete assessment and documentation of ulnar nerve function and distal perfusion with any pisiform or hamate injury.



  • If you suspect injury, obtain carpal tunnel or reverse oblique films.



Trapezium Fractures



General Description



  • Most radial bone of the distal carpal row



  • Articulates with the scaphoid, trapezoid, and first metacarpal



  • Fractures are rare, accounting for 1–4% of carpal fractures.



  • Two general fracture types:




    • Trapezial ridge – serves as attachment for transverse carpal ligament



    • Trapezial body – vertical or comminuted fractures



Mechanism



  • Trapezial body




    • Axial load on the adducted thumb



    • Forced hyperextension and abduction of thumb




      • Trapezium is wedged between first MCP and the radial styloid



  • Trapezial ridge




    • FOOSH with direct impact on ridge



    • Avulsion by the transverse carpal ligament



Presentation



  • Pain and swelling at the thenar eminence, worse with thumb movement.



Physical Examination



  • Limited ROM in thumb due to pain



  • Pain with axial load on first metacarpal



  • Tenderness in distal snuff box

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Sep 1, 2020 | Posted by in SPORT MEDICINE | Comments Off on Chapter 3 – Wrist
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