Summary Phalanx Dislocations are common traumatic injury of the hand involving the proximal interphalangeal joint (PIP) or distal interphalangeal joint (DIP). Diagnosis can be made clinically and are confirmed with orthogonal radiographs. Treatment is closed reduction and splinting unless volar plate entrapment blocks reduction or a concomitant fracture renders the joint unstable. Epidemiology Incidence common injury, especially in athletes Anatomic location PIP joint dislocations volar dorsal lateral fracture-dislocations DIP joint dislocations fracture-dislocations Etiology Mechanism of injury Generally due to direct blow Fracture dislocations due to avulsion impaction shear Associated conditions swan neck deformity nail bed injuries usually associated with distal phalanx fractures Anatomy Distal Interphalangeal Joint osteology hinge joints stabilized by collateral ligaments comprised of proper and accessory collateral ligaments both originate from middle phalanx condyles proper collateral ligament inserts on volar base of distal phalanx accessory collateral ligament inserts on volar plate act as restraint against radial and ulnar deviation terminal extensor tendon inserts on dorsal base of distal phalanx FDP inserts on volar base of distal phalanx volar plate inserts on volar base of distal phalanx does not form checkrein ligaments acts as restraint against hyperextension Proximal Interphalangeal Joint osteology a hinge joint is stabilized by collateral ligaments comprised of proper and accessory collateral ligaments both originate from proximal phalanx condyles proper collateral ligament inserts on volar base of middle phalanx accessory collateral ligament inserts on volar plate act as restraint against radial and ulnar deviation central slip inserts on dorsal base of middle phalanx FDS inserts on volar shaft of middle phalanx volar plate inserts on volar base of middle phalanx forms 2 checkrein ligaments proximally that attach to proximal phalanx acts as restraint against hyperextension Presentation Physical exam inspection pain and deformity of the affected digit skin puckering may indicate interposition of soft tissues within the joint motion important to assess stability of the joint after reduction passive stability lateral stress perform with joint in full extension and in 30° of flexion assesses competency of collateral ligaments when stressed in flexion collateral ligament injury can be classified into 3 grades grade I - pain with no laxity grade II - laxity with firm endpoint and stable arc of motion grade III - gross instability with no endpoint assesses competency of secondary stabilizers (bony anatomy, accessory collateral ligaments, volar plate) when stressed in extension hyperextension assesses competency of volar plate elson test assesses integrity of central slip active stability flexion/extension ability to achieve full ROM indicates stable joint neurovascular evaluate sensation in adjacent digits traction neuropraxia may occur due to stretching of adjacent digital nerves Imaging Radiographs recommended views AP lateral oblique findings V sign results from dorsal joint widening indicates subtle subluxation Diagnosis Clinical and radiographic diagnosis confirmed by history, physical exam, and radiographs PIP Dislocations Introduction dorsal dislocations are more common than volar dislocations dorsal dislocations can lead to a swan neck deformity volar dislocations can lead to a boutonniere deformity Epidemiology incidence most commonly injured joint in the hand Classification dorsal dislocations results from PIPJ hyperextension with longitudinal compression (i.e. ball striking fingertip) leads to tearing of the collateral ligaments and shearing of the volar plate off of the base of middle phalanx commonly seen with small avulsion fracture of the base of the middle phalanx simple hyperextension deformity middle phalanx remains in contact with condyles of proximal phalanx complex bayonet deformity base of middle phalanx not in contact with condyle of proximal phalanx volar plate can act as block to reduction with longitudinal traction volar dislocations simple dislocation without rotation results from rupture of central slip rotatory dislocation with rotation results from rupture of one collateral ligament, with the other remaining intact one of proximal phalangeal condyles buttonholes between the central slip and lateral band lateral dislocations results from rupture of one collateral ligament and at least partial avulsion of volar plate from middle phalanx Treatment nonoperative closed reduction and buddy taping (or splinting) indications simple dorsal dislocation usually performed by patient simple volar dislocation lateral dislocation technique reduction if simple dorsal dislocation, reduce with force directed volarly and in flexion if complex dorsal dislocation, reduce with hyperextension of middle phalanx followed by palmar force if rotatory volar dislocation, reduce by applying traction to finger with MCP and PIP joints in 90° of flexion flexion relaxes volarly displaced lateral band, allowing it to slip back dorsally assess stability after reduction buddy taping to adjacent finger for 3-6 weeks if dorsal dislocation that is stable after reduction lateral dislocation extension block splinting if dorsal dislocation that is unstable after reduction extension splinting for 6-8 weeks if volar dislocation operative open reduction indication failed closed reduction in closed dorsal dislocations, reduction is usually prevented by volar plate interposition in open dorsal dislocations, reduction is usually prevented by dislocated FDP tendon in lateral dislocations, reduction is usually prevented by lateral band interposition technique dorsal dislocations perform dorsal approach with incision between central slip and lateral band rotatory volar dislocations perform dorsolateral approach Complications PIP flexion contracture (pseudoboutonniere) may develop but usually resolves with therapy more commonly seen in volar dislocations swan neck deformity occurs secondary to a volar plate injury seen in dorsal dislocations extensor lag seen in volar dislocations PIP Fracture-Dislocations Introduction PIPJ fracture-dislocations can be volar or dorsal volar lip fractures are the most common fracture pattern seen with dorsal dislocations highly comminuted fracture may occur, known as "pilon" Pathophysiology mechanism of injury avulsion in dorsal PIPJ fracture-dislocations, hyperextension leads to failure of the volar plate resulting in rupture or avulsion of the middle phalangeal volar lip in volar PIPJ fracture-dislocations, hyperflexion leads to failure of the central slip resulting in rupture or avulsion of the middle phalangeal dorsal lip impaction shear axial loading of the finger with the PIPJ in flexion or extension leads to dorsal and volar fracture-dislocations, respectively Classification Hastings Classification (based on amount of P2 articular surface involvement) Type I < 30% (stable) Type II 30-50% (tenuous) Type III > 50% (unstable) Treatment nonoperative closed reduction and splinting indications if < 40% joint involved and stable technique extension block splinting if dorsal fracture-dislocation extension splinting if volar fracture-dislocation outcome regardless of treatment, must achieve adequate joint reduction for favorable long-term outcome operative CRPP vs. ORIF indications if > 40% joint involved and unstable outcomes articular surface reconstruction is desirable, but not necessary for a good clinical outcome PIP subluxation inhibits the gliding arc of the joint and leads to a poor clinical outcome dynamic distraction external fixation indications highly comminuted "pilon" fracture-dislocations volar plate arthroplasty vs. arthrodesis indications chronic injuries hemi-hamate arthroplasty indications younger patients with significant (~50%) middle phalanx joint involvement not amenable to ORIF Technique reduction of the middle phalanx on the condyles of the proximal phalanx is the primary goal adequate volar exposure of the volar plate requires resection of proximal portion of C2 pulley entire A3 pulley distal C1 pulley DIP Dislocations & Fracture-Dislocations Introduction DIPJ dislocations are usually dorsal or lateral volar dislocations are rare often associated with open wounds due to tight soft tissue envelope Classification DIPJ dislocations dorsal volar rare lateral DIPJ fracture-dislocations volar associated with avulsion of dorsal lip/terminal tendon dorsal associated with avulsion of volar lip/FDP Treatment nonoperative closed reduction +/- splinting indications first line of treatment technique if dorsal DIPJ dislocation, reduce with longitudinal traction, direct pressure on dorsal aspect of distal phalanx, and DIPJ flexion perform thorough irrigation and debridement if open dorsal splinting in slight flexion for 2-3 weeks if dorsal dislocation that is unstable after reduction extension splinting for 6 weeks if volar dislocation tuft fractures require no specific treatment can consider temporary splinting, and rarely may require pinning operative open reduction +/- FDP repair indications if two reduction attempts fail in closed dorsal DIPJ dislocation, volar plate interposition is most common block to reduction FDP may be blocking reduction if injury is open in volar DIPJ dislocation, terminal tendon interposition can prevent reduction technique perform FDP repair if dorsal fracture-dislocation where FDP is attached to volar fragment may require percutaneous pinning to support nail bed repair volar plate arthroplasty indications if > 40% joint involved and unstable arthrodesis indications highly comminuted injuries without significant soft tissue loss or vascular injury amputation indications highly comminuted injuries with significant soft tissue loss or neurovascular injury Complications DIPJ stiffness mallet finger deformity seen with volar dislocations