A Nine-Year-Old With a Malunited Little Finger Phalangeal Neck Fracture
A 9-year-old boy is referred five weeks after a fall on the playground. He was treated elsewhere in a ulnar gutter splint for a fracture of the neck of the little finger proximal phalanx. Radiographs now show a united fracture with 45 degrees of apex volar angulation and about 3 mm of dorsal translation of the condylar fragment. He holds the little finger slightly flexed at rest, has a 25-degree extension lag at the proximal interphalangeal joint, and cannot flex the proximal interphalangeal joint past 60 degrees. The metacarpophalangeal joint is supple, there is no rotational overlap, and the other digits are normal. His parents ask whether the finger will straighten out on its own as he grows.
1. Which pediatric phalangeal fractures remodel, which do not, and does this one require correction? Defend your answer on biomechanical grounds rather than by naming a rule.
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Remodeling is a function of location. Fractures adjacent to a physis, such as a Salter-Harris II fracture at the base of the proximal phalanx, remodel well because the growth plate and its intact periosteal envelope can reorient subsequent growth. The phalangeal neck has no adjacent physis and is surrounded by periosteum that is stripped at the time of injury; there is no mechanism by which angulation at the neck can correct itself. Even 15 to 20 degrees of neck angulation persists.
Biomechanically, with 45 degrees of apex volar angulation the condylar fragment sits dorsally and no longer lies coaxial with the shaft. The collateral ligaments, which originate on the condyles, are placed under asymmetric tension, and the base of the middle phalanx articulates with a head that is out of line with the shaft. The consequence is not merely a crooked finger: the arc of proximal interphalangeal motion is lost, which is exactly what he demonstrates with a 25-degree extension lag and flexion limited to 60 degrees.
At five weeks the fracture is united and the soft tissues are already contracting. The deformity will not improve; it will become harder to correct. Corrective osteotomy is indicated, and the only real question is timing.
2. Describe your corrective plan: timing, approach, fixation, and rehabilitation, including any growth-related considerations.
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Timing: within the next few weeks, after acute swelling has settled but before the volar plate and collateral ligaments become a fixed contracture. Do not wait for remodeling that will not occur, and do not wait so long that the joint itself stiffens beyond the reach of therapy.
Approach: mid-axial or dorsal, working between extensor tendons and protecting the dorsal sensory branches. The malunion is identified by the cortical step at the neck. Perform a closing-wedge or rotational osteotomy to restore the head to the shaft axis; a small bone hook can help define the plane.
Fixation: Kirschner wires driven through the condyles into the shaft, or a small lag screw if the fragment permits. Before closing, confirm with fluoroscopy that the collateral origins are isometric and that the proximal interphalangeal joint has a full passive arc; if it does not, release the accessory collateral ligament or volar plate as needed.
Growth: the osteotomy is distal to the proximal phalanx physis, so the growth plate is not at risk; nonetheless avoid wires crossing the physis.
Rehabilitation: protected immobilization for three to four weeks, with the interphalangeal joints exercised in extension between periods of splinting, then active motion with a hand therapist, a night extension splint for six weeks, and no forceful passive mobilization. Warn the family that the final arc may be a few degrees short of normal.
3. What went wrong at the initial presentation, and what should have happened? How does that shape the conversation with the parents now?
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At presentation, a phalangeal neck fracture in a child is not a cast-and-wait fracture. Acceptable position is anatomic or near-anatomic. If closed reduction under fluoroscopy does not achieve that, percutaneous pinning, or open reduction if closed means fail, is indicated. A single post-reduction film is also insufficient: repeat radiographs at one and two weeks are needed, because displacement recurs as swelling subsides and the splint loosens.
The error was applying the general pediatric principle that children remodel to a location where it does not apply. The same principle holds for the condylar region of the distal phalanx and for displaced intra-articular fractures anywhere in the hand.
The conversation now should be direct and non-defensive: explain why the neck behaves differently from the base, that the finger will not straighten on its own, and that an osteotomy offers a good but slightly less predictable result than pinning at the time of injury would have. Set expectations for stiffness and for hand therapy, give the family time to ask questions, and document the discussion. If the family is understandably upset with the outside provider, keep the focus on the child's plan and the timeline.