Carpal bone fracture may lead to pain, weakness of grip, and loss of motion.
Carpal bone fractures may have associated ligament disruption and nerve involvement, which must be recognized and addressed in management to ensure a successful outcome.
The incidence of carpal fracture nonunion is lessened by prompt diagnosis and appropriate treatment, and establishes the basis to apply principles of hand therapy.
Without appropriate therapy to regain motion and strength, the patient may be left with a radiographic record that is acceptable but may in fact have markedly impaired function.
The objective of this chapter is to review the most common presentation of carpal bone fractures and carpal dislocations.
Carpal bones in general are highly mobile, intra-articular, and largely covered by articular cartilage. Blood supply to each of the carpal bones is tenuous and, after injury, avascular necrosis (AVN) may develop, even under the best of treatment protocols. The incidence of nonunion is lessened by prompt diagnosis and appropriate treatment.
Carpal Bone Fractures
Fractures of the Scaphoid
Scaphoid fractures are the most common carpal fractures. They typically occur in young males aged 15 to 30, with an incidence of 35,000 to 50,000 annually. They are uncommon in children.
Scaphoid fractures are produced by wrist hyperextension greater than 90 degrees combined with radial deviation. The scaphoid fails in compression, and displacement is related to the degree of soft tissue disruption. If there is comminution, typically it is on the palmar aspect. Fractures of the scaphoid can be categorized by location within the bone. Waist fractures are most common (approximately 70%) and may be explained by the anatomic location of the radioscaphocapitate ligament. This ligament runs directly palmar to the waist of the scaphoid, and during high-energy loading, forces are concentrated in the contact area between the scaphoid waist and the ligament ( Fig. 73-1 ). Distal pole fractures account for only 10% of fractures, whereas the proximal pole is involved in 20% of the cases.
The vascularity of the scaphoid greatly influences the therapeutic outcome. The distal 20% to 30% of the scaphoid is supplied by perforators that enter through the tuberosity volarly. From 70% to 80% of the scaphoid vascularity is via vessels that enter the dorsal ridge of the bone on the dorsal side, with more than 90% of these vessels entering at or distal to the scaphoid waist. Few communications exist between the dorsal vessels entering at or around the waist and the tuberosity vessels that enter distally and volarly. Consequently, any fracture that occurs at the waist may necessarily interfere with the interosseous blood supply of the bone. Based on the interosseous blood supply and location of fracture, the potential for AVN may be quite high. The proximal pole, which is entirely covered by articular cartilage, is at particular risk because of the retrograde nature of the intraosseous blood flow. The incidence of AVN of the proximal pole approaches 100% and is directly related to the size of the proximal pole.
The diagnosis of a scaphoid fracture is made by a combination of history, clinical examination, and radiographic findings. Snuffbox tenderness is very sensitive but has low specificity for fracture. Radial sensory nerve neuritis and de Quervain’s tenosynovitis may present with pain in this same area. Axial compression of the thumb is most sensitive and most specific in a patient with a history of a fall on a hyperextended wrist.
Scaphoid fractures may be confirmed by standard radiographs, including a posteroanterior (PA), lateral, and scaphoid view. A scaphoid view is taken with the wrist in ulnar deviation to extend the scaphoid so that its entire profile can be seen. In addition, several specialized views may be helpful. A 45-degree pronated view, as well as a PA with the beam angled 20 degrees distal to the scaphoid, may increase the accuracy of diagnosis. Despite appropriate radiographs and clinical examination, some fractures are not readily identified. Occult fractures occur approximately 15% of the time. Bone scans may be indicated. It is 100% sensitive; however, there is approximately a 10% false-positive occurrence. That is to say that 10% of patients undergoing a bone scan that is positive will be overtreated. An MRI scan, 72 hours after injury, is 100% sensitive and specific to the bone; however, cost is a factor. The most useful radiograph is a repeat standard radiograph series 2 to 3 weeks after injury. During this interval, the patient is immobilized in a short-arm thumb spica. Fractures may be demonstrated on the return visit because of bone resorption at the site of fracture secondary to focal osteonecrosis related to the fracture. Alternatively, if no fracture is demonstrated, cast immobilization of 3 weeks often is adequate treatment for a soft tissue injury.
During the treatment of a promptly diagnosed fracture, there often are radiographic changes suggestive of AVN ( Fig. 73-2 ). These changes appear as a radiodense portion of the proximal half of the scaphoid. However, there is no correlation with the prognosis and vascular status. Despite transient changes in the radiographic appearance, healing seems to progress satisfactorily, with resolution of the density changes after healing. An MRI scan is more sensitive (100%) than radiographs (40%) in predicting vascular status of the scaphoid. , In addition, intraoperative determination of vascularity is recommended and is 80% sensitive. At the time of surgery, if AVN is documented, healing is still possible, although the rate declines drastically to 30% to 40%. ,
The rate of scaphoid healing depends on multiple factors. Location of the fracture within the scaphoid is crucial. Proximal pole fractures have a high rate of nonunion despite prompt immobilization. Displacement of greater than 1 mm is critical and suggestive of an associated soft tissue injury, which will preclude predictable bone healing. Displacement manifests as rotation or angulation at the fracture site. A lunate dorsiflexed greater than 15 degrees accompanying a scaphoid fracture may be indicative of carpal instability. Obliquity of the fracture pattern is a predictor of inherent bone stability. Vertical oblique fractures are unstable in compression and sheer, and therefore will be less likely to heal. Vascular supply greatly influences the potential of the scaphoid to heal, as previously noted.
A separate entity is scaphoid AVN. AVN of the scaphoid is known as Preiser’s disease as described by Preiser in 1910 distinguishing AVN from scaphoid fractures. The AVN has been described as the entire bone or just the proximal pole. Diagnosis is made with radiographic evidence of sclerosis and fragmentation of the proximal pole without evidence of fracture. Although Preiser’s disease may present in children, the average age of onset is 40. It classically presents with local pain and tenderness to palpation about the scaphoid.
Treatment of Scaphoid Fractures
Stable nondisplaced fractures of the waist or distal pole of the scaphoid without associated ligamentous injury can be managed with closed treatment. Distal scaphoid fractures typically heal in 8 to 10 weeks in a short-arm thumb spica cast. Fractures of the middle portion of the scaphoid require 6 weeks of a long-arm thumb spica cast, followed by 6 weeks of a short-arm thumb spica cast. Proximal fractures, if they are to be treated nonoperatively, require 6 weeks in a long-arm thumb spica, followed by 6 weeks to 6 months in a short-arm thumb spica.
A relative contraindication to closed treatment is a proximal pole fracture, which is a poorly vascularized, unstable small fragment of bone. Promptly operating on these fractures to rigidly immobilize the fracture site may permit successful revascularization of the proximal fragment with subsequent healing. Additional relative contraindications for closed treatment include associated fractures of the distal radius, polytrauma, or injuries that are more than 6 to 8 weeks old. Absolute contraindications for closed treatment include displacement greater than 1 mm, fracture angulation, or a lunate with a dorsal tilt of greater than 15 degrees. Perilunate and lunate dislocations are considered elsewhere and are contraindications for closed treatment.
Controversy exists over fixation of acute nondisplaced scaphoid fractures. Eighty-eight patients were evaluated in a controlled randomized trial with nondisplaced or minimally displaced acute scaphoid fractures. Forty-four were randomized to internal Herbert’s screw fixation and 44 were randomized to 8-week immobilization in a short-arm cast. They concluded that there was no benefit of early fixation beyond delayed union and became more stringent on operative criteria. They did report that range of motion (ROM), grip strength, and patient evaluation scores were significantly better in the operative group at 8 weeks secondary to casting, but all scores were equivalent at 12 weeks between the groups, although 25% of the nonoperative fractures were not healed at 12 weeks and alternate treatments were explored. More recently in January 2007, Gabl et al. found no significant difference in ROM of the wrist or grip strength, but the operative group had better Disabilities of the Arm, Shoulder, and Hand scores. The fixation group healed at a 43-day mean versus 74 days for the nonoperative group, while the average time of return to work was 8 days for fixation and 55 days for nonoperative patients. They concluded that nonoperative treatment was more expensive than operative treatment in their study.
Treatment of displaced unstable fractures includes closed reduction with percutaneous pinning. Open reduction with percutaneous pinning does not provide adequate stability but is relatively straightforward. Open reduction and internal fixation (ORIF) with a compression screw is favored by most surgeons, because it allows early motion following a relatively short period of immobilization for soft tissue healing. The scaphoid may be approached volarly or dorsally but not from both directions simultaneously. A dorsal approach is relatively straightforward; no AVN was reported, and union was achieved in 10 of 10 patients reported in one article. Although the Herbert’s bone screw was initially quite popular, further mechanical testing showed it to be inferior to cyclic testing when compared with the Acutrak internal device (Acumed, Beaverton, Oregon). Bone grafting for an acute fracture is necessary only for comminuted fractures but is not indicated for nondisplaced or proximal pole fractures. Arthroscopic-assisted screw fixation has been reported. It is technically difficult and is not recommended for displaced fractures, but it deserves further evaluation. After scaphoid ORIF with stable fixation, a wrist-control orthosis is used for 2 to 4 weeks to allow for early soft tissue healing. A removable orthosis is then worn until bone union occurs.
Results of percutaneous fixation for acute displaced scaphoid fractures have been promising. Chen et al. reported 100% union in 11 patients with unstable scaphoid fractures at 10.5 weeks with 6 excellent results and 5 good results with satisfaction, and all 11 patients returned to work able to function as well as before their injury. In 2006, Mathoulin reported 22 nondisplaced and 15 displaced scaphoid fractures with 100% union at 62 days and a return to work in 21 days on average. Percutaneous cannulated screw fixation throughout the literature has consistently had near 100% union near 12 weeks, excellent functional recovery, and earlier return to work than similar fractures treated nonoperatively.
Multiple studies and our clinical experience are dictating that earlier fixation of scaphoid fractures through a percutaneous, limited exposure, or arthroscopically assisted approach is advantageous for fracture union, earlier restoration of function, earlier return to work or sport, and more satisfied patients.
Scaphoid nonunions occur because of undertreatment or misdiagnosis. Patients present late to their treating physician, who misdiagnoses their injury as a wrist sprain. Patients often present with persistent wrist pain or after repeat injury.
On clinical examination, there is typically limited motion of the wrist with minimal swelling or ecchymosis. There is snuffbox tenderness. Radiographs, which include an ulnar-deviated PA of the wrist, demonstrate the nonunion with sclerotic bone margins and cyst formation. If the nonunion has been long standing, often the distal portion of the scaphoid palmar flexes and the lunate dorsiflexes, termed scaphoid nonunion advanced collapse (SNAC). A CT scan along the axis of the scaphoid demonstrates the degree of humpback deformity (flexion deformity at the nonunion site) and is helpful for preoperative planning to determine the type and shape of the graft. MRIs are expensive but may be helpful in determining the vascular status of the proximal pole and predicting the union rate. MRIs also may be helpful to determine whether a conventional bone graft or a vascularized bone graft from the radius is optimally indicated.
The natural history of scaphoid nonunions is not known. It is our perception that if left uncorrected, the wrist develops a SNAC deformity ( Fig. 73-3 ). The SNAC deformity is a dissociative carpal instability in which the kinematics of the wrist are profoundly altered and force transmission across the proximal scaphoid and lunate is abnormal. As part of the SNAC deformity, there is progressive degenerative arthritis, initially found at the distal scaphoid, followed by the capitolunate joint, and finally pancarpal arthritis. ,
Although it is important to address the symptomatic scaphoid nonunion, malunion of the scaphoid is not particularly predictive of the long-term subjective outcome. It is questionable whether an osteotomy is indicated for a scaphoid that has healed in flexion, even when associated with some minor roentgentographic degenerative changes.
Bone grafting is mandatory in the treatment of scaphoid nonunions. Russe described an inlay graft that has the longest clinical experience. The scaphoid is exposed through a palmar incision, with removal of the sclerotic, reactive bone proximal and distal to the nonunion. Cortical cancellous struts are fashioned and are inserted into the nonunion site without supplemental fixation. Although an 80% to 100% healing rate is quoted, the average time to heal is 6 months in a cast. , Immobilization for this period of time is associated with joint stiffness, from which it is difficult to recover.
Time to union can be decreased with some type of internal fixation at the time of bone grafting. The simplest fixation is K-wires, which are not rigid but do decrease time to union. An 89% union rate was reported through a dorsal approach, typically best for proximal pole fractures. Intramedullary compression screws with a bone graft may be used through either a dorsal or palmar approach. The Herbert’s bone screw and the Acutrak screw are the most commonly used, with the latter having more torsional stability. Compression screws provide rigid internal fixation, permitting early mobilization after soft tissue healing, provided an intercalary bone graft has not been used.
If there is a collapse deformity of the scaphoid in which the distal pole has palmarly flexed, a volar wedge-shaped bone graft is necessary to reestablish the normal scaphoid length. The palmar approach is necessary to permit correction of the humpback collapse deformity and insertion of the bone graft. An intercalated bone graft has been suggested to decrease the union rate to approximately 70%, although in recent series this has been reported to be equally successful as nonintercalated bone grafting. , The bone graft is typically harvested from the iliac crest as a cortical cancellous wedge graft and is fashioned to fit the defect after correction of the humpback deformity. A central intermedullary screw is optimal and will decrease time to union. If there is AVN of the proximal pole, the union rate falls to a mere 30%. Degenerative arthritis along the radial styloid–scaphoid contact area requires a radial styloidectomy.
In the difficult situation in which there is an avascular proximal pole and a nonunion, standard bone grafts are not optimal. A vascularized distal radius pedicle bone graft from either the radial or ulnar side can be elevated and interposed in the nonunion site, enhancing the union rate. Fixation of these constructs is difficult with an intermedullary screw, and most commonly, K-wires are used. Nonunions associated with a very small avascular proximal pole are incredibly difficult to treat ( Fig. 73-4 ). Excision of the avascular segment with or without fascial or tendon interpositions has been reported as being successful. However, normal force transmission across the proximal scaphoid and lunate is altered, and the capitate often migrates into this defect, similar to a scapholunate (SL) dissociation. Allograft replacement of the proximal pole has been reported as being successful in eight cases; however, this is a small series without long-term follow-up.
Repeat operation for failed bone graft attempts in nonunions is only 50% successful in obtaining bone union. Internal fixation is strongly recommended, and vascularized bone grafts are indicated if the proximal pole is avascular. Fifty percent of these failed nonunions remain symptomatic despite a successful union. Wrist motion is unimproved. If a second attempt has failed, no further attempts to achieve bone union are warranted because there is a less than 25% union rate; in these cases, salvage procedures are indicated.
If there is limited degenerative arthritis, various options should be considered, depending on the involved periscaphoid joints. A midcarpal fusion, scaphoid excision with triquetral–lunohamate–capitate fusion; and proximal row carpectomy are all reasonable choices in properly selected patients. , Each should be combined with a styloidectomy. All procedures significantly alter the mechanics of the wrist and decrease motion by approximately 50%. Grip strength ranges from 60% to 75% of the unoperated side. Total wrist arthrodesis is recommended for advanced osteoarthritis or multiple failed procedures. Wrist arthrodesis with plate fixation combined with proximal row carpectomy has been reported to be 100% successful in obtaining bone union without iliac crest bone graft. After proximal row carpectomy, the capitate is allowed to settle into the lunate fossa, both surfaces having been prepared. Dorsal plate fixation permits excellent stability and early mobilization of forearm rotation and extensor tendon gliding.
Fractures of the Capitate
The capitate is the largest bone in the wrist. It is stabilized by its articulations, as well as by strong ligaments to its contiguous bones. Distally, it articulates with the third and fourth metacarpal base, ulnarly with the hamate, proximally with the lunate and scaphoid, and radially with the scaphoid and trapezoid. The capitate is part of the stable force transmission column of the wrist. Eighty percent of the force generated by the use of the hand is transmitted across the capitate onto the lunate and the proximal third of the scaphoid and subsequently onto the radius. Isolated fractures of the capitate are uncommon. Most commonly, capitate fractures occur with an associated trans-scaphoid, transcapitate, perilunate fracture–dislocation of the wrist—the scaphocapitate syndrome. In this syndrome, the proximal pole of the capitate is often rotated 180 degrees, and its interosseous blood supply is disrupted. AVN of the proximal pole of the capitate is a recognized complication of this fracture pattern. Nonunions of unrecognized capitate fractures have been described in patients who were not immobilized.
The capitate receives much of its blood supply from the palmar aspect, although there are minor inconsistent dorsal contributions. There is little communication between the dorsal and palmar vascular systems. The proximal pole of the capitate, like the proximal scaphoid, is entirely covered by articular cartilage and similarly has a retrograde vascular flow.
Isolated undisplaced fractures of the capitate may go unrecognized on initial radiographs. When recognized and properly immobilized, these fractures generally heal and revascularization of the proximal pole is possible. In unrecognized fractures, repetitive motion subsequently leads to resorption at the fracture site, nonunion, and failure of the proximal pole to revascularize. If nonunion with AVN develops but is detected before collapse or pericapitate degenerative arthritis, fixation and bone grafting may be successful. Bone graft options might include a vascularized graft. If the proximal capitate pole has already collapsed and osteoarthritic changes are present, limited intercarpal arthrodesis is a good salvage procedure. Management of the scaphocapitate syndrome is discussed under Carpal Fracture-Dislocations.
Fractures of the Hamate
Fractures of the hamate can be classified into fractures involving the hook of the hamate and those involving the body of the hamate. Fractures of the hook are most common and are the result of force transmitted through the base of the palm from an object that is gripped with force. Although typically found associated with a history of an improper golf swing, fractures of the hook of the hamate can also be seen in tennis players. Classically, pain is located over the hook on the palmar side, although pain may also be present on the dorsal aspect. The fracture is typically difficult to see on routine radiographs. Carpal tunnel views are often suggested; however, because of pain the patient is not able to dorsiflex the wrist adequately to see the full profile of the hook. A 30-degree supinated film with the beam centered at the hook of the hamate is sometimes helpful to delineate a fracture. CT scans are extremely helpful in delineating the fracture. Acute nondisplaced fractures may be treated in a short-arm cast and usually heal in 6 to 8 weeks. A displaced fracture requires surgery. Although there has been one report of screw fixation to provide a better fulcrum for the extrinsic flexor tendons, most physicians excise the hook through a volar approach. Because of the difficulty in establishing a diagnosis, the fracture is commonly overlooked, leading to a symptomatic nonunion. Pain located directly over the hook may be associated with ulnar-nerve neuropathy and attritional flexor tendon rupture. Once the hook has been excised, a compressive dressing is applied with a wrist-control orthosis until wound healing occurs, and the patient then begins ROM exercises.
Fractures of the body of the hamate are also difficult to diagnose on routine radiographs. Oblique radiographs may be helpful, but a CT scan is of diagnostic aid in establishing this diagnosis. Often, fractures of the body of the hamate are accompanied by fractures of the base of the fourth and fifth metacarpals. If the fracture is nondisplaced, a short-arm cast may be applied for 4 to 6 weeks. If it is displaced, ORIF is necessary, with stable configurations achieved by K-wires or screws.
Fractures of the Lunate
Isolated fractures of the lunate are unusual and more commonly are a manifestation of Kienböck’s disease. Rarely is there a history of any trauma. The cause of AVN of the lunate may be related to ulnar-negative variance and variations of the interosseous vasculature of the lunate. In ulnar-negative variance, the lunate is seated partially on the lunate fossa of the radius and partially on the soft triangular fibrocartilage spanning between the radius and ulna. Differences in resistance to compressive loads may lead to a microfracture within the lunate. Variations of the lunate interosseous vasculature may be related to the development of AVN. Three distinct vascular patterns have been described, with one pattern having the least communication between dorsal and volar vessels. This variation of blood supply combined with ulnar negativity increases susceptibility to AVN.
The treatment of lunate AVN depends on the stage of involvement. If the diagnosis is made before lunate collapse or the development of osteoarthritis, procedures aimed at unloading the forces on the lunate are indicated. Radial-shortening osteotomy to equalize radioulnar lengths diminishes the compressive loads across the bone and may allow revascularization without collapse.
If not diagnosed early, the natural healing process renders the lunate weak to load, resulting in fracture and bone collapse. Long-term collapse alters carpal mechanics and force distribution, leading to osteoarthritis. At these stages, salvage procedures such as proximal row carpectomy and wrist arthrodesis may be more appropriate to relieve pain.
Fractures of the Triquetrum
Triquetral fractures are the most common nonscaphoid carpal fractures. There are three main types of triquetral fractures: dorsal rim chip fractures, body fractures, and avulsion fracture off the volar aspect. Chip fractures are the most common of these types and may be caused by ligament avulsion with wrist hyperflexion and radial deviation or impaction from the ulnar styloid or hamate with wrist hyperextension. Large dorsal chip fractures may involve significant ligament disruption and result in carpal instability. On the other hand, small chip fractures may be asymptomatic even when left untreated and ununited. Isolated body fractures can result from a direct blow to the ulnar wrist or can occur in association with other injuries such as a perilunate dislocation. Isolated body fractures are usually undisplaced and heal, but associated ligament tears must be addressed. Volar avulsion fractures, which are not common, are likely to involve ligamentous disruption and result in carpal instability.
Small chip fractures and undisplaced body fractures can be treated with 4 to 6 weeks of immobilization. ORIF with ligament repair or reconstruction may be required for larger chip avulsion fractures or displaced fractures with ligamentous disruption.
Fractures of the Pisiform
Pisiform fractures are infrequent and typically result from impaction or a fall directly on the hypothenar eminence. Pisiform fractures represent 1% of all carpal fractures. Ulnar nerve injury or irritation can be associated with pisiform fractures because of its proximity to Guyon’s canal. Tenderness and hypersensitivity over the hypothenar eminence is not uncommon after fracture. The pisiform overlies the triquetrum, and a later sequela of impaction and fracture is pisotriquetral arthritis. Pisiform fractures may also result in nonunion. Acute fractures may be treated with a period of immobilization from 2 to 4 weeks followed by therapy as needed to address any hypersensitivity and limited motion and strength. With nonunion, the pisiform may be excised if symptomatic.
Fractures of the Trapezium
Fracture of the trapezium is the second most frequent nonscaphoid carpal fracture. Trapezial fractures are usually the result of forceful injury and often occur with first metacarpal and distal radius fractures. There are three types of fracture including fracture of the body, fracture of the trapezial ridge, and marginal trapezial metacarpal injuries. Fracture of the trapezium typically presents with localized tenderness. Trapezial ridge fractures may be associated with median nerve compression. Nondisplaced fractures can usually be treated with a thumb spica orthosis or cast for 4 weeks followed by intermittent orthosis use and gentle therapy to restore mobility and strength. Displaced and intra-articular fractures may require ORIF. Tenderness and aching are not uncommon after intra-articular fractures and may progress to degenerative trapezial metacarpal arthritis, which may require arthrodesis or arthroplasty.
Fractures of the Trapezoid
The trapezoid is the most rarely fractured carpal bone because of the security of its bony architecture and the secure ligament attachments to the trapezium, capitate, and second metacarpal. Trapezoid fracture is usually the result of axially directed force along the second metacarpal with resultant fracture dislocation of the second metacarpal or the trapezoid. Nondisplaced fractures may be treated with immobilization for 4 to 6 weeks. Displaced fractures may require closed or open reduction and internal fixation. Degenerative arthritis may be a later result and require trapezoid–second metacarpal arthrodesis.