Fracture Nomenclature for Finger Middle Phalanx Adult
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 Finger Middle Phalanx Adult, the historical and specifically named fractures include:
Fracture-dislocation PIP Joint
Middle Phalanx volar plate avulsion fracture without dislocation
Middle Phalanx Base Pilon fracture
By selecting the name (diagnosis), you will be linked to the introduction section of this Diagnostic Guide dedicated to the selected fracture eponym.
Fractures of the middle phalanx occur less frequently than distal and proximal phalangeal fractures, and they represent some of the least common of all hand fractures. The most prevalent middle phalanx fractures are proximal interphalangeal (PIP) joint avulsion fractures, followed by transverse fractures, and the most common causes are sports-related injuries and machinery accidents. Treating and restoring range of motion (ROM) and function is far more challenging in middle phalanx fractures than it is for distal and proximal phalanges, primarily due to its complex anatomy and the intimate relationship between the flexor and extensor tendons with the bone.1,2
Definitions
- A middle phalanx fracture is a disruption of the mechanical integrity of the middle phalanx.
- A middle phalanx fracture produces a discontinuity in the middle phalanx contours that can be complete or incomplete.
- A middle 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.3-5
- 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 ROM.
- Unstable: will not remain anatomically or nearly anatomically aligned after a successful closed reduction and simple splinting. Typically unstable middle phalanx fractures have significant deformity with comminution, displacement, angulation, and/or shortening.
P - Pattern
- Middle phalanx: oblique, transverse, or comminuted
- Middle phalanx shaft: transverse, oblique, or comminuted with or without shortening
- Middle phalanx base: can involve the PIP joint; these intra-articular fractures usually involve the dorsal or volar lip of the middle phalanx base; large comminuted or displaced fracture fragments will disrupt the congruity of the joint.
- Middle phalanx head: can involve the DIP joint; in these intra-articular fractures, usually one or both condyles of the middle phalanx head with or without displacement; displaced fractures can affect joint congruity.
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 middle phalanx require antibiotics with surgical irrigation and wound debridement.3,6,7
R - Rotation
- Middle phalanx fracture deformity can be caused by rotation of the distal fragment or the proximal fragment. Significant malrotation can affect the position of fingertip during grip.
- Degree of malrotation of the fracture fragments can be used to describe the fracture deformity
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: middle phalanx shaft fractures tend to displace with an apex volar angulation as a result of the pull of adjacent tendon attachments.8 The flexor digitorum superficialis pulls the proximal fragment volarly, while the extensor pulls the distal fragment dorsally.
D - Displacement (Contour)
- Displaced: disrupted cortical contours (eg, middle phalanx shaft fractures are often displaced and rotated due to their flexor tendons2
- Nondisplaced: fracture line(s) are visible and define one or several fracture fragment fragments; however, the external cortical contours are not significantly disrupted, and no fragment displacement is presented
I - Intra-articular involvement
- Fractures that enter a joint with one or more of their fracture lines.
- Middle phalanx fractures can have fragment involvement with the DIP or PIP 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.
- Fractures at the middle phalanx base are often intra-articular and frequently require surgical treatment.9
- Articular fractures of the middle phalanx include condylar fractures, comminuted intra-articular fractures, dorsal, volar or lateral base fractures, fracture-dislocations, impacted fractures of the base of the middle phalanx, and shaft fractures involving the joint.10
C - Closed
- Closed: no associated wounds; the external environment has no connection to the fracture site or any of the fracture fragments.3-5
Middle phalanx fractures: named fractures, fractures with eponyms and other special fractures
Fracture-dislocation PIP Joint
Middle phalanx volar lip fractures are the most common form of osseous injury associated with PIP joint fracture-dislocations.11
- These injuries are generally classified as either dorsal or volar fracture-dislocations of the PIP joint.9
- The amount, direction, and location of the causative force, the position of the PIP joint, and the tension of the intrinsic ligaments and extrinsic muscles determine the extent and type of fracture of the base of the middle phalanx.9
- These injuries are often problematic due to the importance of the PIP joint for general hand function. If too much of the volar base is detached, the collateral ligaments may no longer be able to prevent the middle phalanx from moving dorsally.7
- Volar dislocations of the PIP joint are uncommon and represent disruption of the central slip of the extensor apparatus from the dorsal base of the middle phalanx.12
- Dorsal fracture-dislocations of the PIP joint with volar articular defects of more than 60% have been found to be unstable, while stability is variable with 40% involvement and stable with 20% involvement or less.3
Imaging
- Plain AP and true lateral X-ray views are needed.
- The X-ray will help to distinguish avulsion chip fractures from fracture-dislocations with significant PIP joint involvement.
Treatment
- Surgery may be needed for PIP joint fracture-dislocations, but both conservative and surgical treatments should aim to achieve and maintain complete reduction of the dislocation and restore enough stability to allow early movement.
- Several anatomical structures may also need reconstruction, including the collateral ligament, volar plate, or attachment of the central slip.9
- Closed reduction and immobilization in slight flexion with a dorsal splint for two weeks is indicated as the first line of treatment, if this maintains PIP reduction.
- Prompt and accurate reduction will help to produce satisfactory results, but open reduction of the articular surface may be needed if two reduction attempts fail.
- When a PIP reduction is obtained, an active motion test or at least a passive motion test should be performed to see if the reduction is stable through a normal arc of PIP motion. Unstable PIP fracture dislocations require more surgical intervention and more complex control rehabilitation to achieve a functional ROM without loss of joint reduction.
- Internal fixation may also be needed in some cases with bone grafting rarely needed.9
- Extension block splinting is indicated for dorsal fracture-dislocations if <40% of the joint involved and it is stable.
- if the injury leads to PIP joint instability, dorsal fracture-dislocations typically require surgery such as (ORIF) or hemihamate arthroplasty. The hemi-handmade arthroplasty is excellent option for treating unstable comminuted dorsal PIP joint fracture-dislocations. This procedure is usually indicated when 50% or more of the volar middle phalanx is fractured, thus producing an unstable dislocation. This procedure was first described by Hastings at the 1999 American Society for Surgery the Hand annual meeting. This procedure is done through a volar approach to the PIP joint. A “V” or zigzag incision is made in the skin, the flaps mobilized, the neurovascular structures identified and protected, and the flexor tendon sheath visualized. The A3 pulley is opened, if not already opened by the injury. The A2 and A4 pulleys are preserved. The flexor tendons are retracted exposing the volar plate and more distally the volar fracture in the middle phalanx. This is followed by releasing the attachments of the volar plate to the accessory collateral ligaments. This release allows the volar plate to be folded back proximally, thus exposing the rest of the middle phalanx fracture site. Fragments of bone and articular surface that are attached to the plate are removed. Next, the collateral ligaments are released, and the joint is hyperextended into the “shotgun” position. The defect in the volar middle phalanx’s articular surface is assessed. A rongeur or small saw is used to shape the defect so that it can accommodate a block-shaped osteochondral graft. The defect’s size is measured carefully. The joint is temporary reduced and attention turned to the donor site of the ipsilateral ring, little and hamate joint. After carefully locating the joint, a dorsal incision is made to expose the joint while simultaneously protecting the extensor tendon and the dorsal ulnar sensory nerve. At the ring, little, and hamate joint level the periosteal and capsular flaps are raised to allow visualization of the joint and the dorsal hamate. Next, a block-shaped graft centered on the apex of the hamate at the joint between the ring and little metacarpals is marked and carefully measured. The block graph should be slightly larger than the measured defect in the base of the middle phalanx. The longitudinal hamate cuts are made first. The proximal transfer osteotomy in the hamate is then performed. The final cut is made with the appropriately sized curved osteotome. Some surgeons start proximally through a notch in the proximal hamate, while other surgeons start distally with or without removing a portion of the ring and little metacarpal bases. Do not make the graph too thin, do not fragment the graft, and do not damage the articular surface of the hamate or the metacarpals. Once harvested, the block graft is brought to the finger and placed in the middle phalanx defect. It is temporarily held in place with a small K-wire. The surgeon should align the articular surface anatomically and tilt the graft to assure a cup -shaped surface of the middle phalanx base as visualized from the lateral aspect of the PIP joint. Note, the cartilage of the hamate is often thicker than the cartilage of the middle phalanx which may affect the appearance of the PIP joint on X-Ray. On occasion, adding extra cancellous bone graft from the hamate is needed distally in order to provide the proper tilt of the block-shaped graft and facilitating the curved laterally visualized cup shape of the base of the middle phalanx. Note, morphologic studies have shown this graft is not a perfect match to the volar middle phalanx base but typically variations have not affected the clinical outcome. Secure the graft with two or three 0.9 two 1.5 mm screws through the graft and into the dorsal middle phalanx dorsal cortex. Remove the K wire. Reduce the joint and reattach the volar plate to the stumps of the collateral ligaments left on the base of the middle phalanx. Check the range of motion and the stability. Close the wrist and finger incisions. Splint the PIP joint in 15 to 20 degrees of flexion. Start post-operative range of motion exercises at 7 to 10 days.23-27 For more information on hemihamate arthroplasty see the surgical images below and the links to HAND.E.
- Other options include volar plate arthroplasty, closed reduction and percutaneous pinning (if >40% of the joint is involved and it is unstable), arthrodesis, and dynamic distraction external fixation.3
- Volar fracture-dislocations may be treated conservatively with 4-8-weeks of PIP joint extension splinting if <40% of the joint involved and it is stable.12
- Surgery is needed for volar fracture-dislocations if >40% of the joint involved and it is unstable, and may include ORIF or closed reduction and percutaneous pinning
- Extensive comminution in PIP fracture-dislocations may complicate treatment and require osteochondral bone grafting.7 In several cases, PIP arthrodesis or arthroplasty may be needed.
- ORIF with an autologous hemihamate osteoarticular graft may be required for PIP fracture-dislocations in which more than 50% of the base of the middle phalanx is fractured with an intact dorsal cortex.10
- In athletes with large fracture fragments, open fracture repair with screws and/or K-wires may be necessary to reduce the fracture and achieve PIP joint stability.12
- After lateral stable PIP fracture-dislocations are reduced, buddy taping should be utilized to facilitate the reacquisition of stability.12
Complications
- PIP joint pain
- PIP joint stiffness and contractures
- Post-traumatic osteoarthritis
- Swan neck deformity
- Infection can complicate any open treatment option
- Note that potential complications of the hemi-hamate arthroplasty include :
- Decrease range of motion
- Decreased grip strength
- Infection
- Osteoarthritis
- Graft fragmentation or failure
- Non-union
- Recurrent subluxation or dislocation
- A2 and/or A4 pulley damage
- Secondary surgical treatment for persistent sympotms
Note that potential complications of the hemi-hamate arthroplasty include :
- Decrease range of motion
- Decreased grip strength
- Infection
- Osteoarthritis
- Graft fragmentation or failure
- Non-union
- Recurrent subluxation or dislocation
- A2 and/or A4 pulley damage
- Secondary surgical treatment for persistent symptoms
Outcomes
- Although several surgical options exist for PIP joint fracture-dislocations, no single approach appears to be superior.7
- The volar mini-plate and screw technique has been found to elicit satisfactory short-term results.7
- The hemi-hamate autograft and screw fixation procedure has been associated with satisfactory results in 13 patients with PIP joint fracture-dislocations.10
For ASSH's Hand-e Surgical Video of ORIF PIPJ fracture dislocation through a volar approach by Tuckman:
For ASSH's Hand-e Surgical Video of Hemi-hamate reconstruction of PIPJ fracture dislocation by Izadi:
Middle Phalanx volar plate avulsion fracture without dislocation
- Avulsion fractures of the dorsal base of the middle phalanx represent detachment of the insertion of the central tendon, which can result from an anterior PIP joint dislocation.10
- Volar plate avulsion fractures of the PIP joint usually occur due to passive hyperextension or a dorsal dislocation, and they most often involve only a small fragment of the middle phalangeal base avulsed by the detached volar plate.9,13
- Lateral intra-articular middle phalanx fractures are usually ligamentous avulsion fractures.13
Imaging
- Plain AP and lateral X-ray views are needed.
Treatment
- Dorsal lip avulsion fractures of the middle phalanx caused by the central slip bony avulsions can be treated with closed reduction and dynamic extension splinting of the PIP joint. If closed reduction fails, operative fixation of the fracture fragment or tendon reinsertion should be considered.13
- Volar plate avulsion fractures can be treated conservatively with buddy taping or dorsal block splinting if there is no potential for redislocation.12,13
- Active ROM exercises should be initiated early to minimize stiffness and edema.13
- If the fracture fragment involves more than 40% of the articular surface, instability of the joint can result, and protective dorsal extension block splinting or surgery may be needed in these cases to maintain PIP joint stability. Surgical options include volar plate arthroplasty, ORIF, closed reduction with K-wire fixation, extension block pinning, open fracture repair, and hemihamate autografting procedures.12,13
- If the dorsal avulsed fragment is displaced more than 2 mm, accurate reduction and internal or percutaneous pin fixation are necessary to prevent extensor lag and subsequent boutonnière deformity.10
- Another surgical option for chronic volar plate avulsion fractures is the “volar plate arthroplasty,” in which the volar plate is detached from the middle phalanx, but its soft-tissue attachment to the bone in the volar aspect of the proximal and middle phalanges is maintained, and the distal edge of the volar plate is advanced into the defect in the middle phalanx volar lip. Before advancing the volar plate, the fracture fragment is removed.14
- Buddy taping and early ROM are recommended for lateral middle phalanx avulsion fractures unless there is unacceptable joint incongruity.13
Complications
- Infection
- PIP joint stiffness and flexion contracture
- PIP joint pain
- PIP joint instability
Outcomes
- The “volar plate arthroplasty” has led to significant improvements in ROM, pain, and overall function, and may be considered a respectable option for chronic volar plate avulsion fractures.14
Middle Phalanx Base Pilon fracture
- The term “pilon fracture” is used to describe comminuted articular fractures at the base of the middle phalanx where part of the articular surface of the middle phalanx at the PIP joint is driven into the proximal metaphysis of the base of the middle phalanx.10
- A pilon fracture results from an axial load that causes central articular depression and variable splay of the dorsal/volar and radial/ulnar margins of the bone.10,15
- Disruption in the continuity of the palmar restraints of the collateral ligaments and palmar plate complex with the bony buttress provided by the palmar lip of the middle phalanx base allow dorsal subluxation.15
Imaging
Treatment
- Treating pilon fractures is an ongoing and challenging problem, and consensus is still lacking as to the best treatment approach.
- Conservative options include immobilization and splinting.10,15
- Surgical options include ORIF, skeletal traction through the middle phalanx, and distraction dynamic external fixation (DDEF).10,15
- ORIF is often a technically difficult procedure because of comminution of the bone fragments; stiffness is a common problem, and there is a need for bone grafting.10
- The hemihamate autograft procedure is also precluded because the dorsal cortex is usually fractured.10
Complications
- Infection
- Pain
- Stiffness
- Instability
- Posttraumatic osteoarthritis
Outcomes
- Immobilization and splinting alone have both produced poor outcomes in terms of stiffness, pain, and markedly reduced ROM.10
- Traction and ORIF have led to similar results, and neither was able to accomplish anatomic articular restoration or help patients regain full mobility.10
- Dynamic distraction external fixation (DDEF) has been found to elicit positive outcomes, helping to maintain reduction and restore digital ROM. Early return to work, good pain relief, and high level of patient satisfaction have also been achieved through this procedure, but it is technically demanding and requires significant hand therapy.15
Related Anatomy
- The middle phalanx consists of a distal phalangeal head that articulates at the distal interphalangeal (DIP) joint with the distal phalanx, a narrow diaphyseal shaft, a proximal metaphysis, and a base that articulates at the PIP joint with the proximal phalanx. The base of the middle phalanx has a dorsal and volar lip.
- The ligaments associated with the middle phalanx at the DIP and PIP joints are the dorsal capsule, the collateral ligaments (proper and accessory collaterals), and the volar plates. The retinacular ligament that runs obliquely along the middle phalanx is the final ligament associated with the middle phalanx.
- Tendon attachments include the flexor digitorum superficialis tendon, which is inserted by two slips on either side of the base of the middle phalanx and the extensor tendons. The central slip inserts into the dorsal lip of the base of the middle phalanx, and the terminal extensor tendon traverses the middle phalanx and then inserts into the distal phalanx. The median band of the extensor digitorum tendon passes to the base of the middle phalanx.
- There is a basic anatomical difference between the proximal and middle phalanges: the proximal phalanges have a longer, wider intramedullary canal with more cancellous bone, whereas the middle phalanges have a shorter, narrower intramedullary canal with more cortical bone.16 In general, fractures through cortical bone heal slower than fractures in cancellous bone.
Incidence and Related injuries/conditions
- Metacarpal and phalangeal fractures account for nearly half of all hand injuries that present to the emergency room.15
- Fractures of the middle phalanx are relatively uncommon. Literature reporting their incidence is sparse, but it is approximated that only 10% of all phalangeal fractures occur in the middle phalanx.8
- Phalangeal fractures account for 23% of all below-elbow fractures.18
- Unstable fracture-dislocations of the PIP joint have an estimated annual incidence of 9 per 100,000.11
- Published statistics on the incidence of distal and middle phalanx fractures compared with all fractures of the hand are also scarce.1
- While spiral and oblique fractures of the shaft are more common in the proximal phalanx, transverse fractures tend to be more common in the middle phalanx.10