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  1. 1. PIPJ Anatomy
  2. 2. Proximal Interphalangial Joint Anatomical & functional locus of finger function Site of most common ligament injury in the hand Most ligament injury are incomplete with maintenance of joint congruity & stability In certain injuries (eg. Lateral dislocations & hyperextension injuries) --> complete rupture of one or more supporting structures Treatment based on accurate diagnosis of pathological lesions & degree of clinical dysfunction
  3. 3. Anatomy PIPJ - Hinge joint Arc of motion up to 1100 Stability:  Articular contours  Periarticular ligaments  Secondary stabilization by adjacent tendon & retinacular systems
  4. 4. Anatomy - Bony Factors Head of PP - 2x concentric condyles seperated by an intercondylar notch Condyles (PP) articulate with 2x concave fossa in the broad, flattened base of MP separated by a median ridge Tongue-and-groove contour & breadth of congruence add stability by resisting lateral & rotatory stress (esp. when PIPJ is fully extended)
  5. 5. Anatomy - Ligamentous factors Radial & ulnar collateral ligaments Primary restraints to radial & ulnar deviation force Proper & accessory component Both arise from the concave fossae on lateral aspects of each condyle & pass obliquely & volary to their insertions Anatomically confluent but distinguished by their points of insertion Proper collateral lig. --> volar 1/3 base of MP Accessory collateral lig. --> volar plate
  6. 6. Anatomy - Volar Plate  Floor of joint  Suspended laterally by collateral ligs.  Distal portion inserts across volar base of MP (only densely attached at its lateral margins - col. lig. insertion)  Thinner centrally & blends with MP volar periosteum  Central portion tapers proximally into an areolar sheet & laterally thickens to form a pair of check ligaments  Secondary stabilizer against lateral deviation esp when PIPJ extended but only when collaterals torn
  7. 7. Check ligaments:+Originate from periosteum of PP1 just inside walls ofA2 pulley at its distal margin and are confluent withproximal origins of C1 pulley+prevent hyperextension while permitting full flexionthereby providing maximum stability with minimumbulk
  8. 8. PIPJ Stability  Key: strong conjoined attachment of the paired collateral lig. & the volar plate into the volar 1/3 of the MP  Ligament-box configuration produces a 3D strength that strongly resists PIPJ displacement  For MP displacement to occur, the ligament-box complex must be disrupted in at least 2 planes
  9. 9. PIPJ Stability Based on load to failure cadeveric studies & clinical observation, collateral ligs. fail proximally about 85% of the time while the volar plate avulses distally up to 80% of the time At lower angular velocities of side-to-side deformation, the collateral ligs. tend to fail in their midsubstance
  10. 10. PIPJ - Secondary Stabilization  Secondary stabilization by adjacent tendon & retinacular systems
  11. 11. PIPJ dislocations
  12. 12. Dorsal PIPJ Dislocation
  13. 13. Dorsal PIPJ Dislocations Mechanism: PIPJ hyperextension combined with some degree of longitudinal compression Frequently occurs in ball-handling sports Usually produces soft tissue or bone injury to the distal insertions of the 3D ligament-box complex. The greater the longitudinal force, the more likelihood for fracture dislocation Rarely, VP ruptures volarly & become interposed within the PIPJ causing irreducible dislocation Volar fracture may even become trapped within the flexor sheath and inhibit motion.
  14. 14. Dorsal PIPJ Dislocations  Type I (hyperextension): VP avulsed; incomplete longitudinal split in col. ligs.; articular surfaces remain congruous.  Type II (dorsal dislocation): complete rupture VP; complete split in col. ligs.; MP resting on dorsum of PP.  Type III (fracture-dislocation): disruption at the volar base of MP where VP is inserted; stable vs unstable injuries
  15. 15. Dorsal PIPJ Dislocations  Stable Type III:  fracture < 40% of volar base MP; significant portion of col. ligs. still attached; possible congruous reduction  Unstable Type III:  fracture > 40% of volar base MP; little or no col. ligs. attached; congruous reduction unlikely; depressed volar articular defect
  16. 16. Dorsal PIPJ Dislocations Treatment depends on open vs closed, stable vs unstable injuries Rx principles:  Patient education  Avoidance of prolonged immobilisation
  17. 17. Dorsal PIPJ Dislocations Operative Mx:  Debridement & joint washout for open injuries  Dorsal block splinting  ? Role of primary VP repair  Other specific techniques for unstable PIPJ injuries:  Dynamic skeletal traction  Extension block pinning  Trans-articular pinning  ORIF  Volar plate arthroplasty  FDS tenodesis (for chronic hyperextension deformity of PIPJ)
  18. 18. Dorsal PIPJ Dislocations Complications of operative Mx:  Redisplacement  Angulation  Flexion contracture  DIPJ stiffness