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INTRODUCTION
Although carpal fractures other than those of the scaphoid are uncommon, vigilance in diagnosing these potentially serious fractures is paramount to early and effective treatment. Physical examination and standard plain radiographs may reveal only subtle findings. Special radiographic views and computed tomography (CT) may help elucidate the diagnosis. Treatment is particular to each fracture. This chapter organizes current knowledge of these potentially difficult fractures with boxes outlining diagnosis and treatment guidelines.
According to the ICD-9-CM diagnostic codes (1998), an estimated 188,000 to 226,000 carpal fractures were treated in emergency rooms across the United States. Although the scaphoid accounts for 62% to 87% of carpal fractures, clinicians should not underestimate the frequency with which the remainder of the carpus is fractured. These injuries are often difficult to diagnose, and treatments rendered are often inadequate and delayed.
In recent literature, the incidence of carpal fractures in overall hand injuries has ranged from 8% to 19% since 1990. The incidence of such fractures has not changed significantly since Emmet and Breck reported a 17% incidence in 1958. Nonscaphoid fractures account for 3.2% to 7.7% of these injuries. A breakdown between the proximal and distal row demonstrates fractures of the distal row, accounting for 0.8% to 1.4% of all hand injuries. The hamate is injured most frequently in the distal row, whereas the triquetrum is the second most commonly injured behind the scaphoid with respect to the proximal row. Triquetral fractures vary from 4% to 20% in different studies, whereas the remaining carpal bones—trapezium, hamate, capitate, lunate, pisiform, and trapezoid—are less frequently injured with a range of 0.2% to 3%. The rarity of such fractures offers little outcomes data.
The strategy behind treatment of carpal fractures is to make accurate diagnoses, determine the degree of displacement and the severity of symptoms, and address concomitant injuries. Treatment should be directed not only toward the fracture, but also toward possible surrounding associated injuries. Carpal fractures are relatively uncommon, but care must be given to diagnose and treat these injuries appropriately. Misdiagnosed and untreated carpal fractures may lead to complications such as nonunion, malunion, avascular necrosis (AVN), carpal instability, articular incongruity with resultant osteoarthrosis, neurovascular compression, late tendon rupture, and other problems.
FRACTURES OF THE CAPITATE
Fractures of the capitate are rare and account for only 1.3% of all carpal fractures. Most of these fractures occur in association with additional carpal pathology, particularly scaphoid fractures; isolated fractures of the capitate make up only 0.3% of carpal injuries.
Harrigan first reported on a case of an isolated capitate fracture in 1908. In 1962, Adler and Shaftan reported on 48 cases of isolated capitate fractures. Of the 16 cases with known treatment, 14 were treated by immobilization and 2 by excision. Results were reported in only eight cases; five patients had a “good” result and three had a “poor” result. One of the three with poor results underwent capitolunate fusion. Unfortunately, many of these case reports had incomplete data, and no data were available regarding the incidence of nonunion.
Since 1962, only 25 cases of isolated capitate fractures have been reported. These reports emphasize that early diagnosis is important, since delayed treatment may lead to AVN, nonunion, and post-traumatic arthritis.
The low incidence of isolated capitate fractures is postulated to be due to its anatomic position; the capitate is protected from injury by its surrounding bones, namely, the third and fourth metacarpal, hamate, lunate, scaphoid, and trapezoid bones. In addition, these fractures may be underdiagnosed because little, if any, displacement of fracture fragments occurs, owing to stabilization by intracarpal ligaments. The fracture may also be initially missed because of a paucity of symptoms and a radiographically occult fracture.
Studies by Gelberman and associates demonstrated that the capitate is vulnerable to post-traumatic AVN because of its blood supply. The capitate has a dorsal blood supply with two to four vessels entering the distal two thirds on its concave surface. These vessels supply the body and head in 67% of specimens. One to three vessels enter from the palmar side. The blood vessels to the head of the capitate originate entirely from the palmar surface in 33% of specimens. This retrograde blood flow (similar to that of the scaphoid) is believed to place the capitate with a waist fracture at risk for AVN.
Of the three mechanisms considered to cause isolated fractures of the capitate, the most common is a fall on the palm with the wrist extended. Biomechanical cadaver studies have demonstrated that the dorsal lip of the radius may strike the capitate with hyperextension. The other causes are axial load and a direct blow over the dorsum of the wrist.
Early diagnosis cannot be overemphasized. Unfortunately, the frequent paucity of symptoms contributes to the delay in diagnosis. If an isolated nondisplaced capitate fracture is missed and not immobilized, the proximal segment may rotate with wrist movements producing AVN and/or nonunion due to interruption of the vascularization of the head (proximal pole).
When a displaced capitate fracture occurs as an isolated injury, plain radiographs are usually diagnostic ( Fig. 25-1 A and B). However, nondisplaced isolated capitate fractures may be radiographically occult. Multiple radiographic studies may be required for diagnosis. Posteroanterior radial and ulnar deviation views may help to make nondisplaced capitate waist fractures visible on plain radiographs. Hopkins and Ammann found that early diagnosis of a capitate fracture could be obtained with a technetium-99m-methylene disphosphonate nuclear medicine bone scan and confirmed with CT or magnetic resonance imaging (MRI). Other authors have also reported the usefulness of CT and MRI. Calandruccio and Duncan reported a case of isolated capitate fracture in patients whose initial plain radiographs were considered normal. Treatment was delayed until the fracture was diagnosed with the use of MRI. We prefer MRI to confirm an occult capitate fracture.
Nondisplaced isolated capitate fractures should be treated with short-arm thumb spica cast immobilization for 6 to 8 weeks. Displaced fractures require anatomic reduction to restore normal carpal kinematics. In a long-term follow-up study of capitate fractures, Rand and asssociates recommended anatomic reduction (by open technique if necessary) and immobilization until the fracture united. Volk and associates reported an excellent outcome with open reduction and stabilization using a Herbert screw or Kirschner (K) wires. Internal fixation by K wires or Herbert screws has been reported by others.
The most substantial and under-recognized complication of isolated capitate fractures is that of nonunion. Of the 25 cases of isolated capitate fractures reported in the literature (since 1962), 14 (56%) developed nonunion. Yoshihara and associates reported 12 cases of nonunion in the literature and reported the incidence of nonunion among isolated capitate fractures as being 19.6%. This percentage took into account the 48 cases reported by Adler and Shaftan in 1962 and assumed that none of these patients developed nonunion, although this was not specifically stated.
Of the 14 patients with nonunion in the literature, the average age was 27 years (range 13 to 54). All were diagnosed late, with the average period from injury to definitive diagnosis being 1 year and 11 months (range 3 months to 7 years). The regions of nonunion were the proximal third in 3 cases, the middle third in 10 cases, and the distal third in 1 case. Of the 14 patients with nonunion, 8 did not receive initial treatment after injury because of missed diagnoses. Of the other six patients with nonunions, five were initially treated with immobilization because of suspected contusion or “sprain,” but the fractures failed to unite. As to the initial treatment of the remaining case, the details are unknown. The treatment in 10 cases was cancellous or corticocancellous bone grafting, with or without screw fixation, and observation in 4 cases. Nine of the ten operated patients obtained union. The other patient did not achieve union. Rico and associates reported that cancellous or corticocancellous bone grafting after correction of the rotation of the fragments achieved bone union and restored the length of the capitate, but with some reduction in mobility.
The long-term probability of arthritis after an isolated capitate nonunion is unknown and has not been reported; however, 66% of patients with scaphocapitate syndrome developed post-traumatic arthritis.
AVN of the capitate after an isolated capitate fracture is rare, with three cases reported in the literature, Grend and associates reported that a fracture through the capitate jeopardizes the blood supply to the proximal portion of the bone by interference with the intraosseous circulation, thus potentially resulting in AVN.
The high incidence of nonunion of isolated capitate fractures (56%) has not been previously recognized. All cases were associated with late diagnosis, thus highlighting the importance of early diagnosis and treatment. A patient suspected of having a capitate fracture based on clinical examination and history should undergo further imaging with MRI when initial radiographs are negative. Nondisplaced fractures warrant 6 to 8 weeks in a short-arm thumb spica cast. Displaced fractures require closed versus open reduction and internal fixation with K wires or headless compression screws, depending on the individual fracture pattern ( Box 25-1 ).
CLASSIFICATION
Type 1. Transverse body (see Fig. 25-1 )
Type 2. Transverse proximal pole (waist)
Type 3. Coronal oblique
Type 4. Parasagittal
MECHANISMS
Hyperextension with capitate striking distal radius
Axial load
Direct blow
TREATMENT
Nondisplaced: Short-arm thumb spica cast for 6–8 weeks
Displaced: CRIF vs. ORIF (K wires, headless compression screws)
CRIF, closed reduction internal fixation; ORIF, open reduction internal fixation.
FRACTURES OF THE PISIFORM
Fracture of the pisiform is uncommon, the estimated incidence being less than 1% of all carpal bone fractures. A literature review in all languages reveals 137 reported cases of pisiform fracture. The pisiform bone is a sesamoid bone and is the only carpal bone into which a tendon—the flexor carpi ulnaris (FCU)—inserts. The pisiform articulates with the triquetrum dorsally and serves as the attachment of the transverse carpal ligament, the FCU tendon, and the origin of the abductor digiti minimi muscle. The FCU tendon continues distally as the pisohamate and pisometacarpal ligaments. The pisiform is the last carpal bone to ossify; that is, between the ages of 8 and 12 years. There may be multiple centers of ossification, giving it a fragmented appearance before age 12 years. This normal variant must be distinguished from a fracture.
The mechanism of injury most commonly is direct trauma to the hypothenar eminence or avulsion when the FCU resists forcible hyperextension of the wrist, resulting in an osteochondral or avulsion fracture. This can also be achieved by straining to lift a heavy object. A third mechanism postulated to cause fracture to the pisiform is repetitive trauma, causing vascular disruption and microfractures and then a complete fracture line.
The diagnosis of pisiform fracture is often missed because the adjacent bones obscure clear radiographic imaging of the pisiform on standard views. Lacey and Hodge highlighted the importance of obtaining a reverse oblique wrist radiograph with the wrist in supination. The pisiform fracture was seen only on this view in the two cases they presented. Fleege and associates reported on 10 pisiform fractures, only 5 of which could be diagnosed on posteroanterior radiographs. Sagittal and transverse pisiform fractures may be seen on the posteroanterior view. The carpal tunnel view may also be a useful adjuvant view to diagnose pisiform fractures ( Fig. 25-2 ). It profiles the pisiform with or without the pisotriquetral joint. Abbit and Riddervold presented a case of pisiform fracture that was not recognized on standard wrist views but was diagnosed on the carpal tunnel view. It must be borne in mind that the carpal tunnel view may be unattainable in the acute setting since dorsiflexion is limited by pain. Because of the difficulty with diagnosis, the true incidence of pisiform fractures is probably higher than that reported in the literature.
When plain radiographs remain nondiagnostic in a patient clinically suspected of a pisiform fracture, CT scan of the wrist is the study of choice. The importance of early diagnosis was emphasized by Fleege and colleagues. Missed or delayed treatment of pisiform fractures may result in malunion or nonunion. This may manifest as chronic pain, grip weakness, or limitation of movement. Later sequelae are pisotriquetral chondromalacia, subluxation, and osteoarthritis if the articular surface is poorly aligned.
Associated Ulnar Nerve Palsy
The pisiform forms the ulnar wall of the Guyon tunnel, which contains the ulnar nerve and artery. It is because of this proximity that ulnar nerve palsy can be associated with pisiform fracture. Matsunaga and associates described two patients with a pisiform fracture that resulted in ulnar nerve palsy. Both patients had multiple injuries, resulting in delayed diagnosis of the fracture and subsequent ulnar nerve palsy. Tenderness over the pisiform and normal dorsal sensibility of the ring and small fingers were diagnostic of an ulnar nerve injury at Guyon’s canal. Both patients underwent excision of the entire pisiform: one had full recovery of ulnar nerve function, and one had partial recovery. Two other cases of associated ulnar nerve palsy reported by Howard in 1961 and Israeli and associates in 1982 spontaneously resolved—one after nonoperative treatment with cast immobilization and the other with no treatment.
Because of the rarity of acutely diagnosed pisiform fracture, there are no well-defined guidelines for optimal treatment. Most acute pisiform fractures are treated by immobilization with a cast. Israeli and associates recommended immobilization for 6 weeks. Lacey and Hodge suggest immobilization in a spica cast for 1 month and excision for patients failing this period of immobilization. Georgoulis and associates reported on four cases of pisiform fracture and recommended that acute fractures be treated with immobilization for 4 weeks. They emphasized that excision of the pisiform is not indicated in an acute injury.
For comminuted pisiform fractures, some authors feel that successful union is essentially precluded and early excision facilitates an uncomplicated recovery. Geissler recommended early excision for comminuted pisiform fractures in athletes to promote an uncomplicated recovery and early return to sports. Our preferred method of treatment is immobilization in a short-arm cast for 4 to 6 weeks for all acute fractures and pisiform excision for cases of chronic, symptomatic nonunion or pisotriquetral arthritis. Carroll and Coyle reported complete relief in 65 of 67 patients treated by excision of the pisiform for pisotriquetral joint arthritis. Although this series did not include pisiform fractures, it nonetheless is suggestive of the efficacy of pisiform excision for chronic cases. No significant adverse effect on wrist function has been shown by total pisiform excision.
The indication for ulnar nerve exploration at Guyon’s canal in patients with pisiform fracture has not been clearly defined. According to Israeli and associates, the damage to the ulnar nerve is usually neuropraxia, and nerve palsy should improve within 6 weeks. Nerve exploration is indicated when nerve function does not improve or when it deteriorates. Matsunaga and colleagues recommended nerve exploration when sensory deficits persist for several months or when the ulnar nerve palsy is progressive. They suggested that resolution of the palsy without surgery is unlikely to occur inside Guyon’s canal in the presence of a compressive lesion such as that caused by fractured fragments. Our approach is to observe whether the fracture is nondisplaced. If there is no resolution after 8 to 12 weeks, we decompress Guyon’s canal and perform a total pisiform excision. If symptoms worsen at any point or if there are fracture fragments in Guyon’s canal with ulnar nerve palsy, we prefer early exploration, decompression, and total pisiform excision.
Technique of Pisiform Excision
A palmar approach is used with a curvilinear or zigzag incision slightly radial to the palpable pisiform. The ulnar nerve is exposed, and the pisohamate ligament is divided to decompress Guyon’s canal. This maneuver reduces the development of secondary compression in Guyon’s canal postoperatively. If the fracture is old and the FCU tendon is intact, a longitudinal incision is made in the tendon and periosteum, and the pisiform is shelled out. The tendon and skin are then closed and a soft dressing is applied. If the injury has resulted in a transverse fracture with a wide diastasis, the FCU will not be intact; in such cases the transverse rent in the tendon is used to visualize and shell out the two halves of the pisiform. The tendon is then repaired ( Box 25-2 ).
CLASSIFICATION
Type 1. Transverse (most common)
Type 2. Sagittal (see Fig. 25-2 )
Type 3. Comminuted
Type 4. Pisotriquetral impaction
MECHANISMS
Direct blow
Eccentric FCU load
Repetitive trauma
SPECIAL RADIOGRAPHS (CT scan still often necessary)
Reverse oblique (45-degree supination)
Carpal tunnel view
TREATMENT
Acute
Non- to minimally displaced: Short-arm cast for 4-6 weeks
Widely displaced with loss of FCU continuity: Pisiform excision and FCU repair
Chronic, symptomatic nonunion, or arthritic pisotriquetral joint:
Pisiform excision
FCU, flexor carpi ulnaris.
FRACTURES OF THE TRAPEZIUM
Fractures of the trapezium account for 3% to 5% of all carpal fractures. These fractures are significant injuries when displaced because they affect the important trapeziometacarpal joint of the thumb. Inadequate treatment can lead to permanent impairment based on the substantial forces experienced at the trapeziometacarpal joint in pinch and grip.
Isolated fractures of the trapezium are uncommon. McGuigan and Culp reported on 3 isolated fractures in a multicenter retrospective study of 11 patients with intra-articular fractures of the trapezium. Two of these were caused by motor vehicle collisions and one was due to a fall. Four of the 11 patients had associated Bennett’s fractures, and two had associated radius fractures. One patient had a hamate fracture, and the remaining two patients presented with associated clavicle and scapula fractures, respectively. The association between trapezial and Bennett’s fractures was first noted by Cordrey and Ferrer-Torrels, who wrote “fracture of the first metacarpal is the most common associated injury.”
Trapezial fractures fall into two main categories: fractures involving the palmar ridge ( Fig. 25-3 ) and fractures through the body. The mechanism of injury for palmar ridge fractures is usually a fall on the outstretched palm with fracture either by direct blow or indirect avulsion. The avulsion injury is caused by a sudden tension force applied to the transverse carpal ligament as the thenar and hypothenar eminences diverge. Trapezial palmar ridge fractures are subdivided into type 1 fractures, located at the base of the ridge, and type 2 fractures, located at the tip of the ridge ( Fig. 25-4 ). Both types of fractures are associated with local tenderness. Pain with resisted wrist flexion is common because of the close proximity of the flexor carpi radialis tendon to the fracture site.
Trapezial body fractures may be divided into vertical ( Fig. 25-5 ), horizontal, dorsoradial tuberosity, and comminuted. The mechanism of injury is either axial load through the thumb metacarpal or hyperextension-abduction of the thumb that forces the wrist into a position of maximum radial deviation. The trapezium is wedged between the first metacarpal and the styloid process of the radius; the styloid, functioning as an anvil, fractures the trapezium. The fracture is generally located in the middle of the bone. The lateral fragment remains tethered to the first metacarpal and is often displaced radially and proximally by the pull of the abductor pollicis longus, similar to the mechanism that contributes to a displaced Bennett’s fracture. Horizontal fractures through the trapezium are rare.
Trapezial fractures, regardless of location, are frequently overlooked because of inadequate radiographs. Posteroanterior and lateral views fail to show the entire body of the bone: the posteroanterior view because of superimposition by the trapezoid and base of the second metacarpal, and the lateral view because of superimposition by the hook of the hamate. To visualize the entire body of the trapezium, an oblique radiographic view is necessary. One such view is Bett’s view, also known as the Gedda view in Europe, which is obtained by lifting the elbow off the table, hypothenar eminence off the cassette (on a wedge) with the thumb abducted and extended, hand semipronated, and directing the x-ray beam at the scaphotrapeziotrapezoid joints. In this view, all four articulations of the trapezium are visualized without overlap from the surrounding bones. Visualization of the palmar ridge requires a carpal tunnel view. If a fracture is suspected but not adequately visualized by plain radiographs, a CT scan may confirm the diagnosis and aid in treatment planning.
Treatment of nondisplaced palmar ridge fractures is short-arm thumb spica cast immobilization for 6 weeks. Type 1 fractures through the base of the ridge heal more predictably than type 2 fractures at the tip of the ridge. For symptomatic nonunion of palmar ridge fractures, excision of the bony fragment is indicated.
Treatment of nondisplaced body fractures is short-arm thumb spica cast immobilization for 6 weeks. For displaced fractures, Cordrey and Ferrer-Torrels recommend open reduction and internal fixation of trapezial fractures to restore articular anatomy. Foster and Hastings recommend closed reduction and pinning or open reduction and internal fixation to restore articular congruity. Walker and associates advocate open reduction and internal fixation for all displaced fractures. Similarly, Pointu and associates recommend reduction and fixation for “unstable fractures.” The surgical approach may be dorsal or palmar (Wagner), depending on the location of the fracture.
For comminuted fractures of the trapezium, Jones and Ghorbal showed dismal results in three patients treated with casting. Gelberman and colleagues demonstrated successful treatment with a system of oblique traction. The recommended indication for surgery by McGuigan and Culp is either an articular stepoff less than 2 mm or carpometacarpal subluxation. They reported on three patients with isolated comminuted trapezial fractures and good results at average follow-up of 47 months following open reduction and internal fixation. Two patients had K-wire insertion, and one was fixed with a Herbert screw. We prefer distraction using a transmetacarpal 0.062-inch K wire from the first to second metacarpal shafts or external fixation to unload the joint in conjunction with open reduction internal fixation ( Box 25-3 ).
CLASSIFICATION
Type 1. Vertical intra-articular (see Fig. 25-5 )
Type 2. Horizontal (rare)
Type 3. Dorsoradial tuberosity
Type 4. Palmar ridge (see Fig. 25-3 )
- a.
Type 1. Base (see Fig. 25-4 )
- b.
Type 2. Tip
- a.
Type 5. Comminuted
MECHANISMS
Type 1. Axial compression from 1st metacarpal
Type 2. Horizontal shear
Type 3. Vertical shear on radial styloid
Type 4. Direct blow or avulsion of transverse carpal ligament
Type 5. Axial compression from 1st metacarpal
SPECIAL RADIOGRAPHS (CT scan still often necessary)
Bett’s (or Gedda) view (see text)
Carpal tunnel view (for palmar ridge fractures)
TREATMENT
Body
Nondisplaced: SATSC for 4–6 weeks
Displaced: CRIF vs. ORIF (Wagner vs. dorsal approach)
Comminuted: ORIF combined with traction pin (1st to 2nd metacarpal) or external fixator
Palmar ridge:
Type 1. SATSC for 4–6 weeks (usually heal)
Type 2. SATSC for 4–6 weeks (often do not heal; excise if symptomatic)
CRIF, closed reduction internal fixation; ORIF, open reduction internal fixation; SATSC, short-arm thumb spica cast.
Related posts:
Ulnar Head and Styloid Fractures
Traumatic Extensor Carpi Ulnaris Disruption: Subluxation, Dislocation, Rupture
Management of Soft Tissue Contractures Around the Distal Radioulnar Joint
External Fixation of Distal Radius Fractures
Arthroscopic Trapeziometacarpal Arthroplasty
Bone Tumors of the Hand and Wrist
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