Pastern Flashcards
Where do these fragments origonate from and what proportion of front vs hind limbs are affected in TBs?
Origonate in the origin of the collateral sesamoidean ligament (navicular suspensory)
92% HLs
8% FLs
Origin and insertion of the collateral sesamoidean ligament (CSL)
Originates from the dorso-distal aspect of P1, where it is partially blended with the collateral ligament of the PIPj.
Courses distally and palmar/plantarly to insert on the abaxial and proximal border of the navicular bone
Run palmar to CDET & dorsal to colatteral ligaments of the PIPj
What proportion of TBs treated with ASY removal of dorsal pastern fragmentation raced post-operatively, as reported by Moyer et al (2019 VS)?
Where were most of these fragments located (limb and laterality) and what is their suspected aitiology?
69% of treated horses were able to race PO (vs 76% of controls; no sig diff)
Fragments were most commonly in the hind limbs (92%) and most commonly medially (83%)
Fragments were assoc with the origin of the collateral sesamoidean ligament, immediately dorsal to the origin of the PIPj collateral lig on dorsodistal P1
Suspected traumatic aitiology - avulsion fracture of soft immature bone - vs DOD
SDFT origin and insertion site(s)
Origin: Forelimb - medial humeral epicondyle
Hind limb: supracondyloid fossa of the femur
Insertion (all limbs): Distal palmar/plantar proximal phalynx and proximal palmar/plantar middle phalynx
Additional insertion via medial and lateral retinaculum in hind limbs
DDFT origin and insertion site(s)
Origin: 3 heads in the forelimb:
a) humeral head - medial humeral epicondyle
b) radial head - caudomedial radius (landmark in carpal sheath tenoscopy)
c) ulnar head - medial olecranon
The 3 heads converge proximal to the carpal sheath
2 heads in the hind limb:
a) Lateral digital flexor tendon (larger) - runs in the tarsal sheath over sustentaculum tali
b) Medial digita flexor tendon (smaller) - runs over proximal tubercle of the talus medially, joins LDFT in the proximal metatarsus
Insertion (al limbs): facies flexoria of P3 - broad fan-line insertion
What novel pastern joint injection technique was described by Mereu et al (2019 VS) and what was the injection site
Dorsoproximal midline (DPM) approach
Needle placed midline, 1cm distal to a point halfway between the dorsal coronet and the dorsoproximal extent of P1
What were 4 main findings of Mereu et al (VS 2019) WRT comparison of 4 pastern joint injection techniques?
1) No sig diff in injection accuracy between all techniques (DLF, DLS, PP, DPM)
2) DLS technique was associated with the highest number of time the needle was repositioned
3) DLS technique was also associated with the highest incidence of iatrogenic cartilage damage
4) Novel DPM technique was accurate with no cartialge damage, but was assoc w SQ contrast in 9/15 - may limit dx/tx utility
Give an advantage and disadvantage of the novel dorsoproximal midline pastern injection technique described by Mereu et al (2019 VS)
+ High accuracy (13/15 limbs = 86.6%)
+ No iatrogenic cartilage damage
- High incidence of SQ contrast - may limit usefullness in blocking/medicating
List 5 approaches to the pastern joint.
- Palmaroproximal
- Lateral
- Dorsal
- Dorsolateral
- Dorsolateral flexed
- Dorsoproximal midline
Landmarks and needle insertion site for palmaroproximal approach to the pastern joint
Needle is inserted into a “V”-shaped depression formed by the palmar aspect of the P1 dorsally and the lateral branch of the SDF as it inserts on the middle phalanx palmarodistally. The needle is directed distomedially at an angle of 30° from the transverse plane
Landmarks and needle insertion site for dorsal/dorsolateral approaches to the pastern
Main landmark is a line connecting the medial and lateral palpable prominences of distal P1
Needle can be inserted on this line or 1cm above or below, either on dorsal midline or to the lateral side of CDET. If injecting above this line, need to angle distomedially
Lateral approach to the pastern joint
Needle inserted directly through the lateral collateral ligament midway between the eminences for the attachment of the collateral ligament on the proximal and middle phalanges. The needle is directed in a slightly proximal to distal direction
Palmarolateral approach to the pastern
The site of needle insertion is immediately proximal to the transverse bony prominence on the proximopalmar border of the middle phalanx. The needle is inserted perpendicular to the sagittal plane close to the palmar border of the proximal phalanx
Expected outcomes following conventional PIPj arthrodesis (ie not standing minimally invasive)
72 to 85% return to intended use
Most recent paper is Herthel 2016 EVJ -
74% TBs/WBs and 87% QHs had successful outcomes
13/23 TB/WBs (57%) returned to competition
24/38 (63%) QHs returned to successful competition
Those undergoing HL arthrodesis regardless of breed and use, were more likely to achieve successful competition - 33/45 hindlimbs (73%) and 4/16 forelimbs (25%)
Describe the steps for standing pastern arthrodesis (Heaton et al VCOT 2019)
- ↓4 and IA local
- 1.5’ needle marked placed 1-2cm above the joint in central P1 to determine site of 1st screw
- 1.5 cm vertical stab through skin & CDET dorsally for screw insertion in P1 in a dorsoproximal to palmaro(plantaro)-distal direction
- 4mm drill bit started perpendicular to P1 then directed distally once purchase achieved to cross the joint and then engage the palmar or plantar eminence of proximal P2 w rad guidance.
- In 2 limbs, the central P1 drill hole 5.5 mm to allow lag fashion insertion, remaining 13 were only position screws
- Repeat medial and lateral to the 1st so that 3 5.5. positional TA screws inserted (2 in 1, 4 in 1)
- Skin incisions closed and bandage placed, no cast PO
