2. PIPJ Anatomy

3. 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

4. Anatomy
 PIPJ - Hinge joint
 Arc of motion up to 1100
 Stability:
 Articular contours
 Periarticular ligaments
 Secondary stabilization by adjacent tendon &
retinacular systems

5. 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)

7. 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

10. 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

11. Check ligaments:
+Originate from periosteum of PP1 just inside walls of
A2 pulley at its distal margin and are confluent with
proximal origins of C1 pulley
+prevent hyperextension while permitting full flexion
thereby providing maximum stability with minimum
bulk

13. 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

14. 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

15. PIPJ - Secondary Stabilization
 Secondary
stabilization by
adjacent tendon &
retinacular systems

16. PIPJ dislocations

17. Dorsal PIPJ Dislocation

18. 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.

19. 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

20. 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

37. Dorsal PIPJ Dislocations
 Treatment depends on open vs closed, stable
vs unstable injuries
 Rx principles:
 Patient education
 Avoidance of prolonged immobilisation

38. 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)

39. Dorsal PIPJ Dislocations
 Complications of operative Mx:
 Redisplacement
 Angulation
 Flexion contracture
 DIPJ stiffness