Injuries to the Carpal Bones Revisited

Falls on the outstretched hand, with resultant pain in the carpal region, account for a significant number of referrals to emergency rooms worldwide. Not only do they represent a significant proportion of the radiological workload arising from emergency rooms, interpretation of the images acquired is often difficult due to the complex anatomy of this region, compounded by an inability to obtain adequate views due to patient discomfort. Often, despite apparently normal radiological examinations, patient discomfort persists, prompting a need for further imaging. It is vital that the radiologist be entirely familiar with the bony and ligamentous anatomy of this body region, as well as possess an understanding of the frequent mechanisms of injury. Using a variety of imaging techniques, we illustrate a spectrum of carpal injuries, common and otherwise, explaining the mechanism and typical appearances of each.

Injuries of the carpus and scaphoid

The scaphoid is one of eight carpal bones which lie in two rows (Figure 1). They are articulated together to form a semicircle, the convexity of which is proximal and articulates with the forearm bones. The scaphoid occupies the most radial position (thumb side) in the proximal row. It is a boat-shaped bone, which articulates directly with the radius proximally and is a critical link in the mechanism of the carpus. The scaphoid is commonly divided into four distinct parts: the proximal pole, the waist, the distal body and the tuberosity. It is a key bone to both wrist motion and stability.

The usefulness of CT for patients with carpal bone fractures in the emergency department

OBJECTIVE

The wrist is the most commonly injured joint in the body. However, wrist injuries are often missed in the emergency department (ED). If the fracture is not diagnosed and remains untreated, the patient runs a considerable risk of chronic disability. The utility of CT as an aid in the diagnosis of carpal bone fracture was investigated.

MATERIALS AND METHODS

A retrospective analysis was performed of patients who underwent CT and plain radiography for wrist injury in the ED between March 2003 and February 2006. Plain radiograph interpretations were classified into three groups: (1) the definite fracture group, (2) the no fracture group, and (3) the ambiguous fracture group. The CT results were analysed in relation to the classification of the plain radiograph interpretation. The final diagnoses reviewed from the medical records were used as the reference standard.

RESULTS

36 carpal fractures in 33 patients were identified from 45 patients who underwent plain radiography and CT. The interpretations of plain radiographs were classified into definite fractures (n = 10), ambiguous fractures (n = 15) and no fractures (n = 20). When both the definite fracture and ambiguous fracture groups were considered positive, the sensitivity and specificity were 69.7% and 83.3%, respectively. The sensitivity and specificity of CT scans were both 100%.

CONCLUSION

Emergency physicians should consider CT of the wrist after plain radiography when patients with suspected carpal fracture show normal radiographic findings.

[Sagittal wrist motion following dorsal radiocarpal fracture dislocations]

PURPOSE

Radiocarpal fracture dislocation is a rare, complex injury characterised by dislocation of the radiocarpal joint with avulsion of the dorsal or palmar cortical margin of the distal radius. To evaluate the sagittal motion at the radiocarpal and midcarpal levels following dorsal radiocarpal fracture dislocation (Moneim type I) nine cases were investigated clinically and radiologically.

PATIENTS AND METHOD

In a retrospective follow-up examination, eight patients could be included. The average follow-up was 4.1 years. One patient had a bilateral injury. The operative approach was bilateral in all cases. Restoration of the radial articular surface, filling metaphyseal defect zones with cancellous bone graft and internal fixation with a special T-plate were performed from dorsal. For refixation of the radiocarpal ligaments a small palmar approach was used. Standard anteroposterior and lateral radiographs, as well as lateral views in full extension and flexion were taken at follow-up. Clinical investigation included measurement of active range of motion, grip strength and pain evaluation using the VAS.

RESULTS

Radiological evaluation of the standard lateral view turned out a mean angle between scaphoid and lunatum of 55.6 degrees, capitatum and lunatum of -11.6 degrees and radius and capitatum of 10.5 degrees. In full flexion the following angles were measured: radius/lunatum 15.3 degrees, capitatum/lunatum 18 degrees and between radius and capitatum 30 degrees. In full extension the angles averaged: radius/lunatum -23.9 degrees, capitatum/lunatum -31 degrees and between radius and capitatum -55 degrees. According to the Knirk and Jupiter classification system, five patients presented arthritis stage 1, three arthritis stage 2 and one a stage 3 arthritis. Clinical evaluation showed a mean wrist motion of 55 degrees for extension, 35 degrees for flexion, 88 degrees for pronation, 70 degrees for supination and 25.5 degrees for the mean radial as well as the mean ulnar motion. The average Mayo Wrist Score was 76.1 points.

CONCLUSION

Operative treatment of dorsal radiocarpal fracture dislocation using a bilateral approach led to satisfying results in eight of nine cases with decreased but radiologically evaluated sagittal motion of the proximal row.

Carpal bone fractures

Carpal bone fractures make up a significant proportion of injuries to the wrist. The complex bone shape and articulations make diagnosis more difficult and missed injuries more common. This article reviews carpal bone fractures excluding the scaphoid.

Clinical Evaluation of a Titanium, Headless Variable-Pitched Tapered Cannulated Compression Screw for Repair of Frontal Plane Slab Fractures of the Third Carpal Bone in Thoroughbred Racehorses

OBJECTIVE

To report clinical evaluation of third carpal bone (C3) frontal plane slab fracture repair with the Acutrak screw system.

STUDY DESIGN

Prospective case series.

SAMPLE POPULATION

Racing Thoroughbreds (n=17) with frontal C3 slab fractures.

METHODS

C3 slab fractures in Thoroughbred racehorses (1999-2004) were repaired by use of the Acutrak screw system. Data collected were (1) preoperative variables--gender, age at injury, limb involved, injury occurrence, fracture thickness, complexity, and displacement, race starts and earnings and (2) postoperative variables were: surgical complications, days to first start, race starts, and earnings. A Wilcoxon signed-rank test was used to compare pre- and postoperative starts and earnings; significance was set at P<.05.

RESULTS

Seventeen Thoroughbred racehorses (12 females, 3 males, 2 geldings) were enrolled. Mean (+/-SD) age at injury was 3.3+/-1.0 years. Right carpi (10) were affected more than left (7). Ten injuries occurred during training, 7 during racing. Twelve of 15 horses that raced before injury returned to racing. Average days to first start was 349.3+/-153.9 days. Horses that returned to racing had more starts after repair (median, 6.5 versus 3.5; P=.04) and did not have decreased earnings per start (median, $2452 versus $3061; P=.30).

CONCLUSION

The Acutrak screw system is a useful repair technique for frontal C3 slab fractures in Thoroughbred racehorses.

CLINICAL RELEVANCE

Adequate reduction and stability of C3 slab fractures can be achieved with the Acutrak screw system, decreasing the likelihood of fragment splitting and screw head impingement on carpal soft tissues.

Proximal row carpectomy: an adequate procedure in carpal collapse

Proximal row carpectomy (PRC) is an established procedure in the treatment of advanced radiocarpal arthritis. The aim of this study was to evaluate the individual, functional and radiological results in relation to the initial diagnosis. Seventeen patients (15 men, two women), who had undergone PRC, were evaluated. Their average age at the time of the operation was 48 years (range 21-70 years). The most frequent diagnosis leading to PRC was scaphoid non-union advanced collapse (SNAC), which was observed in nine patients, while in three cases each the condition treated had been scapholunate advanced collapse (SLAC) and perilunate dislocation, and in two cases, Kienboeck's disease. At the time of the follow-up examination (median 65.41 months), a significant improvement in the range of movement was seen. While only four (36%) of the patients with SNAC had radiological signs of arthrosis of the radiocapitate joint, visible radiological involvement was noted in all patients who underwent PRC due to scapholunate dissociation and perilunate dislocation. The results of this study show that PRC is a good way of achieving long-term improvement of the degree of subjective freedom from symptoms and of the functional range of movement. Interruption of ligamentous structures, as in scapholunate dissociation and perilunate dislocation, seems to influence the radiological outcome.

Disorders of the immature carpus

Carpal disorders in children are often associated with developmental abnormalities of structures surrounding the wrist. In addition, carpal ossification throughout childhood has unique influences on pediatric carpal injury. Because the immature carpus is composed of unossified cartilage, carpal abnormalities in young children are frequently undetectable on plain radiographs. Clinical suspicion of an abnormality may elicit further imaging with MRI, which can provide detailed information about cartilaginous structures.

Carpal fractures excluding the scaphoid

Although carpal fractures other than 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. Use of special radiographic views and computed tomography may help elucidate the diagnosis. Treatment is particular to each fracture. Nondisplaced fractures should be treated nonoperatively. For intra-articular carpal bone fractures, virtually any amount of displacement is unacceptable and requires reduction and fixation. This article organizes current knowledge of these potentially difficult fractures, with a table of diagnosis and treatment guidelines.

Osteoid osteoma of the carpal bones. Two case reports

Osteoid osteoma rarely develops in the wrist. The symptoms resemble atypical tenosynovitis, with variations according to the location of the tumor. As a result, diagnostic wanderings are common. In addition, the pain may seem related to an injury, as illustrated by two cases reported herein. Conventional investigations often fail to contribute to the diagnosis. The most specific investigation is thin-slice computed tomography (CT), which can be coupled to magnetic resonance imaging. CT typically visualizes a round lucency surrounded by a rim of sclerosis; in addition, CT shows the exact location of the tumor, particularly relative to neighboring joints. Complete excision of the nidus must be achieved to ensure a permanent cure. Same-stage carpal bone fusion may be required in patients with extensive joint involvement.

Computed Tomographic Documentation of a Comminuted Fourth Carpal Bone Fracture Associated with Carpal Instability Treated by Partial Carpal Arthrodesis in an Arabian Filly

OBJECTIVE

To report treatment of a unilateral comminuted fourth carpal bone (C4) fracture associated with carpal instability by partial carpal arthrodesis (PCA) of the middle carpal joint (MCJ) and carpometacarpal joint (CMCJ).

STUDY DESIGN

Case Report.

ANIMALS

An 8-month-old Arabian filly.

METHODS

A C4 slab fracture was diagnosed radiographically; however, fracture comminution was conclusively diagnosed after computed tomographic (CT) imaging. PCA of the MCJ and CMCJ was performed with 2 narrow dynamic compression plates.

RESULTS

PCA provided appropriate carpal stability and correct limb alignment immediately after surgery. Complete bony fusion with substantial carpal flexion and no lameness at walk or light trot was observed 8 months after surgery.

CONCLUSIONS

Carpal CT was successfully used to define fracture configuration after standard radiographic examination failed to delineate comminution. PCA was selected because of joint instability and lateral carpal collapse of MCJ and CMCJ and can be successfully used to treat comminuted C4 slab fractures associated with carpal instability. Moderate MCJ osteoarthritis without radiocarpal joint involvement allows pain-free, substantial carpal flexion and thus, return to low-level pleasure riding may be possible.

CLINICAL RELEVANCE

CT imaging may more adequately characterize traumatic carpal bone injury, particularly, when carpal bone fracture configuration cannot be determined on standard radiographs. Early PCA of the MCJ and CMCJ is an useful alternative to treat comminuted C4 slab fractures that cannot be reconstructed.

Occult scaphoid fractures: comparison of multidetector CT and MR imaging--initial experience

PURPOSE

To compare the diagnostic performance of multidetector computed tomography (CT) and magnetic resonance (MR) imaging in patients clinically suspected of having a scaphoid fracture and who had normal initial radiographs, with radiographs obtained 6 weeks after trauma as the reference standard.

MATERIALS AND METHODS

The ethics committee approved the study, and all patients gave written informed consent. Twenty-nine patients (17 male, 12 female; age range, 17-62 years; mean age, 34 years +/- 13) underwent multidetector CT and MR imaging within 6 days after trauma. CT data were obtained with 0.5-mm collimation. For image review, 0.7-mm-thick multiplanar reformations were performed in transverse, coronal, and sagittal planes relative to the wrist. The 1.0-T MR examination consisted of coronal and transverse short inversion time inversion-recovery, coronal and transverse T1-weighted spin-echo, and coronal volume-rendered T2-weighted gradient-echo sequences. Two radiologists analyzed the CT and MR images. A binomial test was used to evaluate the significance of the differences between MR imaging and CT in detection of scaphoid fractures and cortical involvement (P < .05).

RESULTS

The 6-week follow-up radiographs depicted a scaphoid fracture in 11 (38%) patients. Eight patients had a cortical fracture, while three patients had only a bandlike lucency within the trabecular portion of the scaphoid. MR imaging depicted all 11 fractures but only three [corrected] cortical fractures. Multidetector CT depicted all eight cortical fractures but failed to depict trabecular fractures. No false-positive fractures were seen on MR or CT images. Differences between MR imaging and CT were not significant for the detection of scaphoid fractures (P = .25) but were significant for cortical involvement (P = .03).

CONCLUSION

Multidetector CT is highly accurate in depicting occult cortical scaphoid fractures but appears inferior to MR imaging in depicting solely trabecular injury. MR imaging is inferior to multidetector CT in depicting cortical involvement.

The exploded hand syndrome: logical evaluation and comprehensive treatment of the severely crushed hand

Severe compressive trauma to the hand presents with multiple soft-tissue and osseous manifestations that often appear unrelated, leading to underrecognition and potential undertreatment of the complex injuries. Approaching the crushed hand with a logical and systematic diagnostic plan allows surgeons to recognize the location and severity of the injury portfolio and direct comprehensive treatment. Both for emphasis and for the purpose of describing the hydraulic mechanism of tissue failure, the term exploded hand syndrome is proposed. The exploded hand connotes the compendium of clinical findings that include skin failure at the webspaces or glabrous border, atypical (usually longitudinal) fracture patterns of the tubular bones, and axial carpal dissociations. These are accompanied by extensive compromise of the interosseous musculature that is extruded or may exhibit evolving compartment syndrome. Understanding the trauma mechanism and patterns of injury in the exploded hand will maximize awareness and guide surgical reconstruction and rehabilitation.

How do clinical features help identify paediatric patients with fractures following blunt wrist trauma?

OBJECTIVE

Wrist injuries are a common presentation to the emergency department (ED). There are no validated decision rules to help clinicians evaluate paediatric wrist trauma. This study aimed to identify which clinical features are diagnostically useful in deciding the need for a wrist radiograph, and then to develop a clinical decision rule.

METHODS

This prospective cohort study was carried out in the ED of Sheffield Children's Hospital. Eligible patients were recruited if presenting within 72 hours following blunt wrist trauma. A standardised data collection form was completed for all patients. The outcome measure was the presence or absence of a fracture. Univariate analysis was performed with the chi2 test. Associated variables (p<0.2) were entered into a multivariate model. Classification and regression tree (CART) analysis was used to derive the clinical decision rule.

RESULTS

In total, 227 patients were recruited and 106 children were diagnosed with fractures (47%). Of 10 clinical features analysed, six were found by univariate analysis to be associated with a fracture. CART analysis identified the presence of radial tenderness, focal swelling, or an abnormal supination/pronation as the best discriminatory features. Cross fold validation of this decision rule had a sensitivity of 99.1% (95% confidence interval 94.8% to 100%) and a specificity of 24.0% (17.2% to 32.3%). The radiography rate would be 87%.

CONCLUSIONS

Radial tenderness, focal swelling, and abnormal supination/pronation are associated with wrist fractures in children. The clinical decision rule derived from these features had a high sensitivity, but low specificity, and would not substantially alter our current radiography rate. The potential for a clinical decision rule for paediatric wrist trauma appears limited.

Acute os styloideum injury in an elite athlete

The os styloideum, an accessory carpal bone, may suffer injury during traumatic wrist flexion. The case described corresponds to an acute os styloideum injury in an elite athlete; a diagnosis made using high-resolution computed tomography and magnetic resonance imaging permitted not only the identification of the anomaly and associated abnormalities but also ruled out more significant injury to the extensor carpi radialis brevis.

Palmar carpal osteochondral fragments in racehorses: 31 cases (1994–2004)

OBJECTIVE

To evaluate records of racehorses with palmar carpal osteochondral fragments and determine whether the fragments were indicators of the severity of pathologic joint changes or prognosis.

DESIGN

Retrospective case series.

ANIMALS

31 racehorses.

PROCEDURES

Medical records, radiographs, and videos of arthroscopic procedures were reviewed. Information gathered included signalment; location, number, and size of the primary lesion; number and size of palmar carpal fragments; and details pertaining to surgical procedures. Outcome variables were obtained from race records.

RESULTS

31 horses met the selection criteria. Multiple palmar fragments were diagnosed in 58% of horses; small fragments (< 3 mm in diameter) were most common (52% of horses). Fifty-two percent of the horses returned to racing, 48% returned to racing and earned money, and 32% had at least 5 more starts. Horses with multiple fragments had significantly less earnings per start and lower performance index values after surgery than those with 1 fragment. Horses with palmar fragments < 3 mm in diameter were significantly less likely to return to racing and have 5 starts or to win money after surgery than horses with larger fragments.

CONCLUSIONS AND CLINICAL RELEVANCE

Palmar carpal osteochondral fragments can be used as an indicator of clinically important joint pathology and as a prognostic indicator in racehorses. Horses with multiple small fragments were less likely to successfully return to racing than horses with only dorsally located carpal fragments or horses with 1 or 2 large palmar fragments. When possible, removal of palmar carpal osteochondral fragments should be considered.

Transscaphoid transcapitate transtriquetral perilunate fracture-dislocation: a case report

We present a rare stage III greater arc fracture-dislocation of the carpus including transscaphoid, transcapitate, and transtriquetral dorsal perilunate fracture-dislocation.

Association between Extrinsic and Intrinsic Carpal Ligament Injuries at MR Arthrography and Carpal Instability at Radiography: Initial Observations

PURPOSE

To retrospectively compare the presence or absence of carpal instability on radiographs with the findings of magnetic resonance (MR) arthrographic evaluation of intrinsic and extrinsic ligament tears in patients with chronic wrist pain.

MATERIALS AND METHODS

The institutional review board approved this study and did not require informed consent. Signs of carpal instability were assessed on static and dynamic radiographs of the wrist obtained in 72 patients (24 female, 48 male; mean age, 36 years; age range, 14-59 years) with posttraumatic wrist pain. MR arthrography was subsequently performed. Two musculoskeletal radiologists independently analyzed the radiographs and MR images. Each intrinsic and extrinsic ligament was individually evaluated for the presence of a ligament tear. The extent of the tear also was recorded. Interobserver agreement regarding MR arthrographic findings was tested by calculating kappa statistics. Statistical comparison between radiography and MR arthrography was performed by using the Fisher exact test.

RESULTS

Twenty-five triangular fibrocartilage complex, 18 (five partial, 13 complete) scapholunate ligament, and 25 (10 partial, 15 complete) lunotriquetral ligament tears were visualized. Twenty-two (all complete) extrinsic ligament tears were detected: two radial collateral ligament, 10 radioscaphocapitate ligament, and 10 radiolunotriquetral ligament tears. Interobserver agreement regarding intrinsic and extrinsic ligament tear detection at MR arthrography was excellent (kappa = 0.80). Nineteen patients had evidence of carpal instability on radiographs. Fourteen (52%) of 27 patients with at least one complete intrinsic lesion had no sign of carpal instability. On the other hand, the association of scapholunate ligament and/or lunotriquetral ligament and extrinsic ligament tears was significantly correlated (P < .001) with carpal instability at radiography.

CONCLUSION

The presence or absence of carpal instability on radiographs depends on the association between intrinsic and extrinsic ligament tears-even partial ones-rather than on the presence of intrinsic ligament tears alone, even when the tears are complete.

[An inveterate fracture of the barton type of the distal radius with dislocation in the radiocarpal joint--case history]

Barton's fracture was first described and isolated as a disease entity in 1839. It is a quite rare fracture constituting, according to various authors 1.5-2.3% of the distal radius fractures. It is usually accompanied with subluxation or luxation in the radiocarpal joint. In the study we present treatment, dealing with operative difficulties and rehabilitation in a 52-year-old patient with an inveterate fracture of the Barton type of the distal radius with dislocation in the radiocarpal joint. He was previously treated by a local quack. The patient underwent an operative treatment; fragments were anatomically repositioned and a stable fixation was applied. As a result of treatment and intensive rehabilitation, we achieved synostosis and functionality of the wrist and left hand.

Simultaneous Dislocation of the Carpometacarpal and Metacarpophalangeal Joints of the Thumb in a Motorcyclist

Combined dislocation of more than one joint in a single finger is a rare injury. An amateur motorcyclist sustained simultaneous closed dislocation of the carpometacarpal and metacarpophalangeal joints of the thumb as an isolated injury after falling from his motorcycle during an abrupt stop from high speed. The dislocated joints were reduced by closed means on the day of injury. After 18 months, the functional result of his right thumb was excellent. The mechanism of injury and management of this uncommon motorcycle injury is reported.