What is the treatment for a Salter-Harris (S-H) 2 thumb proximal phalange physis injury?

Treatment of Salter-Harris Type 2 Thumb Proximal Phalanx Fracture

For Salter-Harris type 2 fractures of the thumb proximal phalanx, treatment depends critically on fracture displacement and stability: non-displaced or minimally displaced fractures (<2-3mm) with a stable joint should be treated with rigid thumb spica immobilization for 3-6 weeks, while fractures with >3mm displacement or joint instability require surgical fixation with open reduction and K-wire placement. 1, 2, 3

Initial Assessment

When evaluating these injuries, obtain at minimum 2-view radiographs (PA and lateral), though adding an oblique view increases diagnostic yield 1. Key radiographic features to assess include:

• Fracture displacement: Measure the gap between fragments—displacement >3mm is a surgical indication 1
• Joint stability: Perform lateral stress testing of the metacarpophalangeal joint 2
• Associated injuries: Look for clinical signs of nail-bed laceration (subungual hematoma, nail plate subluxation, eponychial fold laceration, bleeding from under the nail plate) which may indicate an open fracture requiring surgical exploration 4

Treatment Algorithm

Non-Operative Management (Minimally Displaced, Stable Fractures)

For fractures with <2-3mm displacement and no lateral instability on stress testing 1, 2:

• Immobilize with a thumb spica cast or splint for 3-6 weeks 1, 3
• The modified thumb spica cast should incorporate the thumb in a balanced position while allowing full wrist flexion and extension 3
• Obtain follow-up radiographs at 10-14 days to ensure fracture position is maintained 1
• Non-operative treatment achieves excellent outcomes even with fibrous non-union (60% rate), provided the joint remains stable 2

Surgical Management (Displaced or Unstable Fractures)

Surgery is indicated when 1, 2, 4:

• Fracture displacement exceeds 3mm 1
• Lateral instability is present on stress testing 2
• Clinical features suggest nail-bed laceration (which occurs in 82% of cases with clinical signs and requires exploration) 4
• Soft-tissue interposition is suspected (found in 47% of explored fractures) 4

Surgical technique consists of open reduction with K-wire fixation, which provides excellent long-term outcomes 5, 4. At exploration, repair any nail-bed lacerations identified 4.

Common Pitfalls

• Uninterrupted immobilization is critical—even brief splint removal can restart the healing timeline 6
• Do not miss open fractures: Any clinical sign of nail-bed injury warrants surgical exploration, as 82% will have a nail-bed laceration and 47% will have soft-tissue interposition blocking reduction 4
• Beware of the "Seymour fracture": Salter-Harris fractures with nail-bed injury are open fractures requiring surgical debridement and repair 7, 4
• Infectious complications occur in approximately 8% of surgically treated cases 4

Expected Outcomes

With appropriate treatment, patients achieve 2, 5:

• Full range of motion and grip strength equivalent to the uninjured side 2
• Return to all sporting activities and employment 2
• 93% report no pain on movement 2
• Minor diaphyseal constriction may occur but does not affect function 5