Fracture Nomenclature for Thumb Proximal Phalanx Fracture Pediatric
Hand Surgery Resource’s Diagnostic Guides describe fractures by the anatomical name of the fractured bone and then characterize the fracture by the Acronym:
In addition, anatomically named fractures are often also identified by specific eponyms or other special features.
For the Thumb Proximal Phalanx Fracture Pediatric, the historical and specifically named fractures include:
Salter-Harris avulsion fracture of the UCL
Proximal phalanx neck fracture
Complex MP joint dislocation
By selecting the name (diagnosis), you will be linked to the introduction section of this Diagnostic Guide dedicated to the selected fracture eponym.
The hand is the most commonly fractured location in children, and the majority of these fractures affect the phalanges. Of the phalanges, the proximal phalanx is most frequently involved, and the thumb ranks second behind the little finger in terms of fracture frequency in the digits of children. Sporting activities—like skiing and biking—are often responsible for these types of injuries, fractures and fracture-dislocations. Fracture-dislocations are more common than true dislocations because younger bones, especially at the growth plate, are more fragile than the ligaments. In addition, age has an effect on the type of fracture sustained, as Salter-Harris type II fractures appear to be the dominant fracture of the proximal phalanx base among children aged <10 years, while Salter-Harris type III fractures are most common in adolescents older than 11 years. Although pediatric fractures share some similarities with their adult counterparts, the presence of physes and other developmental changes in children and adolescents makes it requisite that careful consideration be given to these factors to ensure appropriate diagnosis and management.1-5
Definitions
- A pediatric thumb proximal phalanx fracture is a disruption of the mechanical integrity of the thumb proximal phalanx.
- A pediatric thumb proximal phalanx fracture produces a discontinuity in the proximal phalanx contours that can be complete or incomplete.
- A pediatric thumb proximal phalanx fracture is caused by a direct force that exceeds the breaking point of the bone.
Hand Surgery Resource’s Fracture Description and Characterization Acronym
SPORADIC
S – Stability; P – Pattern; O – Open; R – Rotation; A – Angulation; D – Displacement; I – Intra-articular; C – Closed
S - Stability (stable or unstable)
- Universally accepted definitions of clinical fracture stability is not well defined in the hand surgery literature.6-8
- Stable: fracture fragment pattern is generally nondisplaced or minimally displaced. It does not require reduction, and the fracture fragments’ alignment is maintained with simple splinting. However, most definitions define a stable fracture as one that will maintain anatomical alignment after a simple closed reduction and splinting. Some authors add that stable fractures remain aligned, even when adjacent joints are put to a partial range of motion (ROM).
- Unstable: will not remain anatomically or nearly anatomically aligned after a successful closed reduction and simple splinting. Typically unstable pediatric thumb proximal phalanx fractures have significant deformity with comminution, displacement, angulation, and/or shortening.
- In the pediatric population, even most displaced fractures are easily reduced closed and often quite stable.5
P - Pattern
- Thumb proximal phalanx head: oblique, transverse, or comminuted; can involve the interphalangeal (IP) joint; these are intra-articular fractures that usually affect one or both condyles of the thumb proximal phalanx head with or without displacement; displaced fractures can affect joint congruity.
- Thumb proximal phalanx neck: fractures of the neck of the phalanges occur almost exclusively in children and are most common in the proximal phalanx; these fractures occur distal to the collateral ligament recess of the proximal phalanx, and presenting patients typically have apex volar angulation with associated sagittal and subcondylar malalignment.4,5,9,10
- Thumb proximal phalanx shaft: transverse, oblique, or comminuted, with or without shortening; these fractures are less common than other proximal phalanx fractures.11
- Thumb proximal phalanx base: the most common site of injury in the bone, these fractures typically occur when the finger is abducted past the normal range of the metacarpophalangeal (MP) joint.4,11,12 May be intra- or extra-articular and usually involves the dorsal or volar lip of the proximal phalanx base.10
- Intra-articular fractures are associated with concomitant injury of the ulnar collateral ligament (UCL).10
O - Open
- Open: a wound connects the external environment to the fracture site. The wound provides a pathway for bacteria to reach and infect the fracture site. As a result, there is always a risk for chronic osteomyelitis. Therefore, open fractures of the pediatric thumb proximal phalanx require antibiotics with surgical irrigation and wound debridement.6,13,14
R - Rotation
- Pediatric thumb proximal phalanx fracture deformity can be caused by rotation of the distal fragment on the proximal fragment.
- Degree of malrotation of the fracture fragments can be used to describe the fracture deformity; this is not a common type of fracture deformity in the pediatric thumb proximal phalanx.
- Radial or ulnar deviation and malrotation of pediatric thumb proximal phalanx neck fractures are also possible, and radiographs can underestimate the degree of clinical rotational deformity.5
- Some pediatric thumb proximal phalanx fractures will have substantial rotational deformities that can only be detected through clinical evaluation.11
- Salter-Harris fractures of the pediatric thumb proximal phalanx with associated rotational deformity require appropriate management, as the deformity can persist if left untreated, i.e. rotational deformities are not as likely to correct with remodeling and growth as other fracture deformities.1
A - Angulation (fracture fragments in relationship to one another)
- Angulation is measured in degrees after identifying the direction of the apex of the angulation.
- Straight: no angulatory deformity
- Angulated: bent at the fracture site
- Example: pediatric thumb proximal phalanx neck fractures usually have apex volar angulation with associated sagittal and subcondylar malalignment.4
D - Displacement (contour)
- Displaced: disrupted cortical contours
- Nondisplaced: fracture line defining one or several fracture fragments; however, the external cortical contours are not significantly disrupted
- Pediatric thumb proximal phalanx neck fractures are prone to proximal displacement, and most are displaced with dorsal translation and extension angulation.5,12
- Displaced epiphyseal fractures of the pediatric thumb proximal phalanx will result in articular and physeal incongruity and therefore require surgery.15
I - Intra-articular involvement
- Fractures that enter a joint with one or more of their fracture lines.
- Pediatric thumb proximal phalanx fractures can have fragment involvement with the IP or MP joints.
- If a fracture line enters a joint but does not displace the articular surface of the joint, then it is unlikely that this fracture will predispose to posttraumatic osteoarthritis. If the articular surface is separated or there is a step-off in the articular surface then the congruity of the joint will be compromised and the risk of posttraumatic osteoarthritis increases significantly.
C - Closed
- Closed: no associated wounds; the external environment has no connection to the fracture site or any of the fracture fragments.6-8
Pediatric thumb proximal phalanx fractures: named fractures, fractures with eponyms and other special fractures
Salter-Harris avulsion fracture of the UCL
- Injuries to the UCL at the thumb’s proximal phalanx base are less common and not as thoroughly described in children compared to those in the adult population. As in adults, these injuries result from a hyperabduction force applied to an extended thumb, and sporting activities like skiing and biking are often responsible.16,17
- The primary difference between these injuries is the anatomy of the pediatric thumb, as the UCL runs from the head of the metacarpal to the inner aspect of the proximal phalanx base, where it connects almost entirely to the epiphysis. Due to this anatomy, hyperabduction rarely results in an isolated rupture of the UCL, but instead tends to cause intra-articular fracture at the base of the thumb.15,18 These are primarily Salter-Harris fractures due to their frequent involvement of the physes. Salter-Harris avulsion fractures of the UCL at the ulnar portion of the epiphysis are considered to be the pediatric equivalent of “bony skier’s thumb.”10,15
- Rupture or avulsion of the insertion or origin of the UCL can also result in these injuries.2,16 It is generally accepted that Salter-Harris type III fractures are the most common fractures of the thumb proximal phalanx base in adolescents aged ≥11 years because the central part of the physis begins to close around this age. Agreement on the most prevalent type of base fracture in children younger than 10 years, however, is less certain, which led to a prospective study on 58 children in this age cohort.
- Results showed that that Salter-Harris type II was the most common fracture type in children aged <10 years, accounting for 72% of these fractures. There were no Salter-Harris type III, IV, or V fractures in this cohort.3
- By contrast, another similar study found juxta-epiphyseal II fractures to be the most common fracture type in the proximal phalanx base of the other fingers of children. This may be related to the microscopic anatomy of the physis and metaphysis in these bones.19
- These injuries destabilize the first MP joint and result in loss of thumb pinch and grip power if not properly treated. A displaced epiphyseal fracture of the proximal phalanx will also result in articular and physeal incongruity.10,15
- Although isolated rupture of the UCL of the thumb in children is rare, it is still important to suspect it in these injuries. Surgical exploration and/or MRI may also be necessary to determine if a Stener lesion is present, as missing this type of lesion can lead to long-term disability.18
Imaging
- Posteroanterior, lateral and oblique X-ray views are recommended, but it is important to note that some epiphyseal fractures will have normal X-rays, and surgical exploration may therefore be necessary.3,16
- Stress radiographs and advanced imaging studies (eg, ultrasound, MRI, arthrogram) should only performed in ambiguous cases.2
Treatment
- Nondisplaced fractures should be treated by cast immobilization for 4-6 weeks, while displaced fractures typically require surgical intervention to evaluate the displacement of the UCL or fracture fragment outside the adductor aponeurosis, such as a Stener lesion.2,20
- Displaced Salter-Harris III fractures at the base of the thumb proximal phalanx (displaced >1.5 mm or rotated fragment) require open reduction and internal fixation (ORIF) to restore the integrity of the UCL and to obtain a congruous joint surface.2
- The surgical technique should include a longitudinal incision along the attachment site of the adductor aponeurosis into the extensor pollicis longus (EPL), which allows for a longitudinal arthrotomy. The fracture fragment and joint surface should then be inspected and the type of fixation selected.
- There are multiple fixation options, which include K-wire fixation, tension wire fixation, and mini-screw placement.
- Closure requires careful repair of the adductor aponeurosis to the EPL, and a thumb spica cast that covers the percutaneous K-wire should be applied.
- The K-wire is then removed 4 weeks after surgery and ROM is started. A splint is fabricated to protect the repair during activities for 1 additional month.2
- Chronic pediatric UCL injuries are more difficult to manage, and UCL reconstruction is complicated, especially in young children with an open physis. Chrondrodesis with an attempt to preserve the physis or arthrodesis may be the most reliable option.2
Complications
- MP joint instability
- Nonunion
- Malunion
- Impaired grip/pinch strength
- Posttraumatic osteoarthritis
Outcomes
- One 9-year-old girl with a Salter-Harris II fracture at the base of her thumb proximal phalanx with rotational deformity was treated with closed reduction consisting of retraction and derotation of the fracture. Results were successful and resolved the rotational deformity.1
Proximal phalanx neck fracture
- These transverse extra-articular fractures through the neck of the proximal phalanx occur almost exclusively in the pediatric population. Also known as subcapital, subcondylar, and supracondylar phalangeal fractures, these injuries may be either displaced or nondisplaced.3,21
- In almost all cases, proximal phalanx neck fractures result from the thumb being entrapped in a closing door. It is thought that displacement of the distal fragment occurs as the child violently attempts to withdraw the trapped thumb, and the withdrawal opens the fracture site enough for rotation of the distal fragment to occur.3
- Nonunion in these fractures is rare, but the following factors may increase the risk for it developing:
- Younger age group with incomplete ossification of condyles
- Displaced fractures
- Failure to obtain a true lateral X-ray
- Inadequate initial management by closed reduction and splinting
- Delay of K-wire fixation beyond 3 weeks of injury
- Premature removal of the K-wire used to fix the fracture3,22
Imaging
- A lateral radiographic view is best for diagnosing these injuries, as an anteroposterior view can easily miss the fracture.
Treatment
- Most nondisplaced thumb proximal phalanx neck fractures can be treated with splinting. Displaced fractures, however, are usually unstable after closed reduction, and ORIF with K-wire fixation is therefore required in most of these cases. Without surgical intervention, there is a significant risk of malunion and nonunion.3
- In most of these fractures, K-wires should be left in place for 3-6 weeks.3
- In severely displaced fractures, the distal fragment can rotate to as much as 180°.21
- Nonunion is these cases is rare, but if it does develop, the treatment of choice is bone grafting.3
- This may be accomplished with either cancellous or corticocancellous bone grafts.22
- The ideal time for treating nonunion with bone grafting is during childhood, but delayed grafting may be needed in cases of neglected nonunion.22
Complications
- Nonunion
- Avascular necrosis
- Malunion
Outcomes
- In one study, a series of 4 patients had established nonunion after failed closed reduction and splinting. They were referred for additional treatment 6-8 months after the initial injury and underwent iliac crest bone grafting.
- Radiological union was observed in all cases after 6 weeks, and all thumbs were clinically stable, with no pain on manipulation after removal of the K-wire.
- At the final follow-up 1-2 years later, all patients had normal ROM at the MP and basal joints of the thumb.21
- Another study of adults with neglected nonunion resulting from thumb proximal phalanx fractures earlier in life were treated surgically with delayed iliac crest bone grafting. This intervention led to positive functional outcomes and a high patient satisfaction rate.22
Complex MP joint dislocation (Without Fracture)
- Dislocation of the thumb’s MP joint in children is uncommon on account of their bones being weaker than the surrounding ligaments and soft tissues. These injuries usually stem from an axial blow causing forced hyperextension of the MP joint, with sporting activities and fall on an outstretched hand (FOOSH) injuries often being responsible.23-25
- Pediatric MP dislocations at the thumb can be classified as one of three types:
- Incomplete dislocation: the collateral ligaments are intact, and the injury can be managed by closed reduction.
- Simple complete dislocation: the volar plate and collateral ligaments rupture, but the volar plate is not interposed in the joint, which usually presents as hyperextension deformity. Can also be managed by closed reduction.
- Complex complete dislocation: the volar plate is displaced—possibly due to an avulsion fracture—and interposed in the joint, with the metacarpal and proximal phalanx usually lying parallel to each other. This type of dislocation is uncommon. These fracture-dislocations are irreducible injuries that require surgical intervention. Other interposed obstacles that may prevent closed reduction include flexor tendons, the collateral ligaments, the joint capsule, and sesamoid bones.24. Most pediatric MP joint dislocations are dorsal, with volar dislocations being extremely rare. 23,24
Imaging
- Anteroposterior, lateral, and oblique X-ray views are needed, with the lateral view being most helpful.
Treatment
- Incomplete and simple complete MP dislocations can be effectively treated with closed reduction—which may be accomplished with the McLaughlin technique—and brief periods of immobilization followed by mobilization exercises to prevent joint stiffness.24
- Repeated attempts at close reduction should be avoided, because this can convert a simple dislocation into a complex complete dislocation. This is also possible when the proper reduction technique is not used for these injuries, and open reduction may therefore be needed in cases of failed or improper closed reduction.24,25
- Because complex complete MP dislocations are irreducible, open reduction is needed, which may be performed with either a dorsal or volar approach.24
- The optimal treatment option is still controversial, and the choice depends on the surgeon’s preference and presence of concomitant injuries.25
- The volar approach carries a higher risk of neurovascular injury due to the anatomy and location of neurovascular bundles, but the volar plate can be directly visualised and repaired easily when using it.24,25
- The dorsal approach allows for surgical exploration of the MP joint and provides excellent exposure of the volar plate, but its disadvantage is the longitudinal splitting of the volar plate to reduce the MP joint, which is irreparable.24,25
- If using a volar approach, extreme care is necessary to protect the displaced radial digital neurovascular pedicle. Early protected mobilization is also important to lessen the risk of stiffness.15
- Arthroscopic reduction is another technically demanding surgical option that may be considered.25
- Immobilization with a thumb spica cast for approximately 4 weeks, followed by active ROM exercises, is necessary after all cases of open reduction.24
Complications
- Stiffness
- Premature physis closure
- Posttraumatic osteoarthritis
- Osteonecrosis
Outcomes
- Studies on outcomes after treating children with MP dislocations of the thumb are scarce.24
- In one study on 10 patients with MP dislocations, incomplete and simple complete dislocations were managed with closed reduction using the McLaughlin technique, while irreducible dislocations were managed with open reduction using either a volar or dorsal approach.
- Of the 10 patients, 9 had excellent results at the final follow-up, regaining full painless ROM at the MP joint without any instability, and they also achieved good pinch strength. Mild stiffness in one patient treated with open reduction was likely due to him presenting on the fourth day after trauma and his lack of compliance with physical therapy.24
- In another study of 37 pediatric patients with MP joint dislocation, 33 were treated with closed reduction and 4 required open reduction.
- Of these patients, 35 had excellent results at follow-up, with normal ROM of the MP and no pain. There was also no incidence of infection, recurrent dislocation, or severe stiffness.23
Related Anatomy
- The pediatric thumb proximal phalanx consists of a distal phalangeal head that articulates at the IP joint with the distal phalanx, a supportive neck, a narrow diaphyseal shaft, a proximal metaphysis, and a base that articulates at the MP joint with the thumb metacarpal. The physis is located at the base of the proximal phalanx, which has a dorsal and volar lip and is most susceptible to fracture along the thumb ray.2,4
- The ligaments associated with the thumb proximal phalanx at the IP and MP joints are the joint capsule, the proper and accessory UCL and radial collateral ligament (RCL), and the volar plates. The collateral ligaments about the MP joint originate from the metacarpal epiphysis and insert almost entirely on the epiphysis of the proximal phalanx, while the collaterals about the IP joint originate from the phalangeal head, cross the physis, and insert onto the metaphysis and epiphysis of the distal phalanges. This configuration partially explains why Salter-Harris III fractures are so common at the thumb MP joint, and Salter-Harris II fractures at the IP joint.2
- Tendon attachments of the thumb proximal phalanx include the abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, and extensor pollicis brevis, which inserts onto the epiphysis of the proximal phalanx.2
Incidence and Related injuries/conditions
- Metacarpal and phalangeal fractures account for about 21% of all pediatric fractures, and the phalanges are the most commonly injured hand bones in this population.4,10
- The annual incidence of phalangeal fractures in children and adolescents up to 19 years old is approximately 2.7%.26
- The proximal phalanx is the most frequently fractured phalangeal bone in the pediatric population. These fractures are about twice as common as those of the distal and middle phalanges.27-29
- The little finger is the most commonly fractured digit, followed by the thumb.28-30
- In one study, the incidence of thumb fracture was found to be low in children less than 10 years of age, but a steep rise was noted after this age, which led to the thumb becoming the second most commonly fractured ray in adolescents.28
- In the thumb, the proximal phalanx (52%) was more frequently fractured than the metacarpal (31%) and distal phalanx (17%).28
- The incidence of all phalangeal fractures is highest in children aged 10-14 years, which coincides with the time that most children begin playing contact sports.4
- Despite the fact that most patients are right-hand dominant, the distribution of phalangeal fractures is generally found to be similar in both the right and left hands.28,30
- Physeal injuries account for 15-30% of all pediatric fractures, and significant growth disturbance may occur in approximately 10% of cases. These types of injuries are most common during the adolescent growth spurt between ages 10-16, and are more common in boys than in girls.30
- Salter-Harris II fractures have been shown to have an incidence of 39% of hand fractures overall, and they represent approximately 90% of all Salter-Harris fractures in the hand.32