Ch 55 carpus, metacarpus and digits Flashcards
Carpal Bones
how many?
joints?
ginglymus (hinge) joint
Seven
- Intermedioradial carpal bone
- Ulnar carpal bone
- Accessory carpal bone
- C1-4
sesamoid bone located in the tendon of insertion of the abductor pollicis longus muscle on the medial side
antebrachiocarpal joint
middle carpal joint
metacarpophalangeal joint
carpal ligaments
short extra-articular and intra-articular ligaments, an articular disc (sometimes known as the radioulnar ligament, which connects the radius to the ulna), palmar fibrocartilage, and the joint capsule.
dorsal surface
- radioulnar ligament (articular disc)
- dorsal radiocarpal ligament
- short ulnar collateral ligament
- short radial collateral ligament
palmar side
- short radial collateral ligament
- palmar radiocarpal ligament
- palmar ulnocarpal ligament
- accessory metacarpal ligaments
- flexor retinaculum
- palmar fibrocartilage is attached to all the proximal carpal bones
metacarpal and phalanges
metacarpal
- proximal base
- a middle body
- distal head
- Metacarpals II through V are all weight bearing, but metacarpals III and IV are longer
- intermetacarpal joints are joints between the proximal ends of adjacent metacarpal bones
- interosseous metacarpal ligaments
semoids
- two palmar sesamoid bones
- joined by the intersesamoidean ligament. The lateral and medial sesamoidean ligaments
- two cruciate ligaments on the palmar aspect
- dorsal sesamoid bones are attached by the tendons of the common digital extensor
phalanges
- A joint capsule and extensor tendons unite the proximal interphalangeal joints dorsally
- palmar side, the joint capsule unites with the flexor tendons.
- collateral ligamnets
- interdigital ligaments hold the digits together and are the major supportive structures of the pad
Where are the metacarpal physes located?
When do they fuse?
MC1 proximally
MCII-V distally
Fuse by 5-6m
How are the metacarpophalangeal sesamoids numbered?
2 sesamoids per metacarpophalangeal joint, numbered 1-8 from medial to lateral
List some anatomical differences of the cat manus
- Absense of a straight medial collateral ligament
- Dogs lack a dorsal elastic ligament attachment to the head of the middle phalanx, and the shape of the head is different from that of the cat and therefore dogs canot retract their claws as cats cat
How is joint motion often graphed?
Joint angle vs %gait cycle
data show that the static carpus extension angle while standing is less than the dynamic joint angle at a walk or trot
sources of variability during data acquisition. Dog morphology, limb measurement techniques, gait speed (walk or trot), marker placement, skin movements, and the ability of the recording system to accurately identify the markers
joint angles are described in this chapter as negative in flexion and positive in extension
rapid flexion occurs and is followed by rapid extension during the swing phase.
The metacarpophalangeal joint angle at the walk changed little during the stance phase
The antebrachiocarpal joint at a walk has been reported to be approximately 18 degrees throughout most of the stance phase
at a trot > peak antebrachiocarpal joint angle was 23.9 ± 3.9
arthrodesis of antebrachiocarpal and metacarpophalangeal joints> recognized that altering normal motion of these joints will result in compensatory change in some of the joints of the ipsilateral and contralateral limbs.
What palmar ligaments have the highest elastic modulus?
How do the palmar ligaments tend to fail?
many of the injuries of the manus result from hyperextension
Acessorometacarpal ligaments
Modes of failure:
- 58.3% mid-ligament
- 22.9% avulsion fracture
- 18.8% at bone-ligament interface
Carpal Fractures
- can be difficult to diagnose on standard radiographic projections (consdier oblique etc or CT)
- comminuted and articular # likely lead to OA
Intermedioradial Carpal Bone Fractures
- reported in case series in the literature, occur in active dogs that have not sustained significant trauma
- breed predilection (Boxer, English Springer Spaniel, Setters, and Pointers)
- dorsal slab fractures,
- midbody sagittal (dorsoproximolateral to palmarodistomedial oblique)
- comminuted T-shaped fractures.
What is a proposed mechanism of nontraumatic fractures of the intermedioradial carpal bone?
Incomplete fusion of the centres of ossification
What form of intermedioradial carpal bone fractures are seen in Greyhounds?
What are the treatment options?
Oblique midbody fractures of the right limb
Chip or avulsion at the attachment of the palmar carpometacarpal ligament or the oblique part of the short radial collateral ligament
Tx
- Lag screw
- Headless self-compressing cannulated screw (5 cases, good outcome)
- K-wires
- Excision of fragments
- External coaptation (incomplete or nondisplaced) > difficult to speculate about the true outcome
splint or cast, for 6 weeks following surgery and to severely limit patient activity.
Osteoarthritis is an expected outcome even after anatomic repair
outcome related to restoration of joint surfaces and severity of OA
dorsal surgical approach
palmaromedial surgical approach
repair midbody intermedioradial carpal bone fractures
Accessory Carpal Bone Fractures
right carpus (80%) in greyhound
proposed mechanism
- full weight bearing on carpus
- accessory carpal bone is acting as a fulcrum for the palmar carpal ligaments and the flexor tendons to prevent hyperextension of the carpus
large clinical study, all type II and type III fractures were present in combination with type I fractures.
91% of the 11 dogs followed in the study returned to racing after successful surgical repair
Tx
- fragment removal
- internal fixation, usually with a 1.5 or 2.0 mm screw in lag fashion or positional.
preserve the paired accessorometacarpal ligaments and the accessoroulnar carpal ligaments during the repair
- type I and type II > examine the articular surface
- Type V > considered nonsurgical
- External coaptation
- Data are insufficient to predict long-term outcome
What are the types of accessory carpal bone fracture?
Type I (67%): Avulsion of distal margin at articular surface. Attached of ligament to ulnar carpal bone. Ia palmerolateral, Ib palmaromedial
Type II (13%): Proximal margin of the articular surface. Attachment of ligaments to distal radius and ulna
Type III (3%): Avulsion of distal surface at palmar end. Attach to MC IV and V
Type IV (12%): Avulsion at insertion of flexor carpi ulnaris at caudoproximal surface
Type V (5%): comminuted
What are the guidelines for deciding if MC/MT fractures require surgery?
- More than 2 MC/MTs fractured in same manus
- Fractures involving both the primary weight bearing bones
- Articular
- Displaced by over 50%
- Involve the base of MC/MT II/V (collateral attachment)
- Large-breed or athletic/working dog
surgical fixation with bone plates may have improved alignment of the fractures radiographically > No study has demonstrated that any for of treatment if better than any other
largest studies are retrospective
MC/MT fractures
All treatments (conservative or surgical) had a modest complication rate
all methods of internal fixation use implants that are not rigid. Therefore, patients have external coaptation regardless
unclear whether external bandages or coaptation significantly protects the internal fixation implants
body is the most commonly fractured area
complications
- delayed union or nonunion,
- osteomyelitis,
- implant loosening,
- bandage-associated disease,
- osteoarthritic changes,
- synostoses.
How are MC injuries classified in racing Greyhounds?
Which are most commonly fractured?
Type 1: Endosteal and cortical bone thickening, clinical lame on day of and after the race. Rest for 3m with gradual return
Type 2: Minimally displaced hairline fractures. External coaptation for 6-8wk
Type 3: Complete, displaced fractures. Surgery and external coaptation
MCV of left thoracic limb and MCII of right limb most common
A study of 23 dogs, only 4 returned to race in more than 10 races with some success
MC/MT fractures surgery
alignment and apposition of fractures before placement of the coaptation
medial/lateral surgical approach MC II/V
dorsal approach directly over the metacarpal
A tourniquet
Avulsion fractures:
- bones is a ligament attachment site
- screws in lag fashion or pin and tension band
- If the fragment is too small, digit can be amputated if only one metacarpal bone is affected
diaphyseal fractures:
- IM pin placed in normograde fashion
- dowel pinning
- 1.5 or 2.0 mm plate and screws
- External skeletal fixation with small pins and epoxy putty bars/spider
unclear whether the plates interfere with the extensor tendons
Digit Fractures and Luxations
Traumatic fractures
- splint coaptation for 4 to 8 weeks
- sufficient size, small bone plates or screws placed in lag fashion can be used to repair diaphyseal or avulsion #
- digit can be amputated
Proximal interphalangeal joint sprains or luxations
- rest and nonsteroidal antiinflammatory medications +/- splint
- Arthrodesis with a dorsal plate
Splint not necessary for more than 6 to 8 weeks.
Radiographic evidence of bone healing will lag behind clinical callus formation of these small bones
What is a potential cause of sesamoid disease?
What sesamoids are most commonly effected?
What breeds are predisposed?
- Sesamoids II and VII have significantly fewer vascular foramina on the bones than all other sesamoids
- II and VII most commonly effected
- Greyhounds and Rottweiler overrepresented
sesamoid disease
causes?
causes of sesamoid disease
- trauma,
- congenital disorders of ossification,
- degenerative joint diseases from abnormal forces,
- osteonecrosis secondary to vascular compromise
dogs that present with thoracic limb lameness will have additional orthopedic conditions that could be the primary cause of the lameness because sesamoid disease is often subclinical
STUDY: observational study comparing the long-term outcomes of a group of dogs treated conservatively versus surgically
- Better clincal results and less OA change in those threated conservatively with rest
- try conservative management first are fair for the level of evidence.
- Surgery is limited to removal
What is the most common injury of the canine carpus?
Hyperextension
causes: fall from heights, jumps, no trauma i.e. immune-mediated arthropathies
Palmar Ligaments and Palmar Fibrocartilage injury
- results in loss of palmar support and hyperextension of the carpus.
- Both medial and lateral collateral ligaments have a role in preventing carpal hyperextension.
- Luxation of the carpus may occur at the proximal (antebrachiocarpal), middle carpal, or distal (carpometacarpal) level
- antebrachiocarpal joint was injured in 50% of the cats
Dx
- routine lateral and dorsopalmar views, stress lateral (with the carpus in extension) and medial and dorsopalmar stress
- Conservative management of carpal hyperextension is rarely successful
- Pancarpal or partial carpal arthrodesis is generally accepted as the best treatment
PCA plates
- Review: clinical/biomechanical studies of plates demonstrates that despite differences biomechanically, all plates can be used successfully.
- Comparison 2.7/3.5 mm hybrid and the 3.5 mm DCP > significant difference between bending moments at failure, favoring the hybrid
- percentage of bone diameter removed for screw placement is important
CastLess vs hybrid (finite element model).
- bone distal to the last metacarpal screw had the greatest stress
- CastLess plate had 20% less risk of metacarpal fracture than the hybrid
- no significant differences in the stiffness
- failure rarely due to plate breakage and usually due to technical mistakes
locking alps vs hybrid
- no difference
Pancarpal specialty plates
stepped hybrid plates
designed with a smaller metacarpal screw, a long version
best angle of 10 to 12 degrees of extension without manual bending
CastLess plate is designed with the distal screws engaging metacarpals III and IV at an angle of 8 degrees.
Carpal Luxation
- location (antebrachiocarpal, middle carpal, or carpometacarpal) is considered severe and will likely require a pancarpal arthrodesis
- Complete luxations are uncommon compared with subluxations
Metacarpophalangeal Osteoarthritis
36 dogs with radiographic osteoarthritis were identified, but only 9 of those dogs presented with osteoarthritis as a clinical problem
- were clinical were more likely to have swelling over the affected digits.
- Metacarpals IV and V were affected more often
- periosteal reaction is extensive (up to 33% of the length of the metacarpal bone) > smooth with no destructive lesions
- distinguish from primary bone neoplasia of a metacarpal bone
Reconstruction of the flexor carpi ulnaris tendon with a fascia lata autograft in two dogs with carpal hyperextension
Yuichiro Tani 2022
Damage to the FCU tendon were located at the ulnar head on ultrasonographic and intraoperative examinations
immobilized by a type I external skeletal fixation for 6 weeks
No recurrence of carpal hyperextension
was observed over 36 months after surgery
hyperextension due to disruption of the palmar ligament or some kind of
tendon injury, the only tendon involved in stability during extension of the carpus is that of the flexor carpi ulnaris muscle (FCU)
FCU
- humeral head (caput humerale), medial
epicondyle of the humerus
ulnar head (caputulnare), proximomedial ulna
- both muscle bellies insert onto the accessory carpal bone
Retrospective Comparison of Titanium Hybrid Locking Plate (ALPS) with Stainless Steel Hybrid Dynamic Compression Plate for Pancarpal Arthrodesis: 23 Dogs
Chong 2022
Median follow-up time was 1,157 days (range: 62– 1,902 days) for ALPS group and 340 days (range: 43–1,465 days) for HDCP
Major and minor complications and surgical site infection rates were not statistically different between the two groups.
Plate fracture occurred in 2/15 ALPS PCA and screw loosening occurred in 4/14 HDCP PCA. Full function was achieved in 8/12 and 8/11 of ALPS and HDCP cases, respectively, which was not statistically different
major complications: 26-35%
SSI: 30-35%
conclusion: Given the relatively poor
results and high complication rates in both our ALPS and HDCP cohort, further improvements required
Excessive plate bending can increase the
bending moment over the contoured length which results in
increased plate deformation during loading.16 This may have
contributed to two plate fractures seen in the ALPS cohort
Recent PCA plate designs are
longer, with MCov of 65 to 74% reported for stepped hybrid plates9 and 75.8 to 92.5% for castless plates7 compared with 56.5% for our HDCP cohort and 74% for ALPS
Screw loosening rates
11.2 to 28.6%3,10 have been reported for HDCP,
whereas lower screw loosening rates of 0 to 7.6%3,7, 7.6%2
and 11%9 have been reported for castless plates
Postoperative metacarpal fracture rates
for HDCP, castless plates and
stepped hybrid plates were reported at 7.7, 1.9, and 3.8%
respectively
lower bending stiffness and strength of the
ALPS compared with the HDCP are due to titanium having a
lower modulus of elasticity compared with stainless steel.
Healing of PCA is reported to plateau after 84 days (12 weeks) which
was postulated to be due to load-sharing of the bone plate
during locomotion
cases that
have received bilateral PCA could have been assessed separately
from unilateral PCA cases, as the outcome and complications
may differ significantly;
Outcome of rest with or without bandaging
for treatment of carpal flexural contracture deformities in puppies: 47 puppies and 75 joints (2000–2018)
Petazzoni 2022
retrospective,
All dogs responded to conservative management, with all dogs regaining full extension of the antebrachiocarpal joint and ambulating normally at the time of the final visit
For dogs with grade 3 severity, however, mean time to recovery was significantly shorter for dogs treated with rest and bandaging than for dogs treated with rest alone.
MANAGEMENT OF FELINE
CARPAL INJURIES
What are the options and
when is arthrodesis indicated
Rachel M Basa and Kenneth A Johnson 2019
cats only have a single short radial collateral ligament, also known as the medial collateral ligament. This means that, in the cat, antebrachiocarpal subluxation is possible with rupture of the dorsal joint capsule
and short radial collateral ligament alone.
Diagnosis of an isolated short radial collateral
ligament injury can be made using stress
radiography. In the cat, valgus stress does not create significant medial opening of the joint spaces, despite the presence of an injured short radial collateral ligament. Varus stressed radiographs are often more useful
determining which ligaments
and joint levels are affected requires careful
examination and often stress radiography. When pancarpal arthrodesis is performed in the cat, it has been reported to reduce the height of jumping and to increase reluctance to climb. This is speculated to be due to reduced pronation and supination movement of the carpus.
Evidence base: The current evidence base for
management of feline carpal injuries is grade III or IV, with most of the studies being retrospective case series
The authors believe that ligamentous injury is common enough to warrant
routine use of stress radiography where there is a known traumatic carpal injury,
and that primary repair with rigid fixation will provide a more favourable outcome
than using pancarpal arthrodesis as a first-line treatment.
✜ Pancarpal arthrodesis should remain a salvage procedure, reserved
for select cases and those with ongoing pain and lameness.
Kinematics of the Feline Antebrachiocarpal Joint from Supination to Pronation
Rachel M. Basa 2021
The proximal row of carpal bones translate and rotate independently from the ulna in the cat during pronation of the antebrachium. This may have future
implications in the diagnosis and management of feline carpal injuries involving the antebrachiocarpal joint.
feline carpal joint is not purely a ginglymus
because movements other than flexion and extension at the level of the antebrachiocarpal joint may occur
PCA > important to understand the extent to which this surgical procedure may compromise supination and pronation.
Comparison between high-field 3 Tesla MRI and computed
tomography with and without arthrography for visualization
of canine carpal ligaments: A cadaveric study
Castelli 2019
Prospective descriptive study.
Study population: Cadavers from dogs weighing more than 20 kg
Arthrography improved the capabilities of MRI but not of CT for
visualization of the canine carpal ligaments. Magnetic resonance arthrography was
particularly useful for evaluation of the stabilizers of the antebrachiocarpal joint.
Clinical significance: 3 Tesla MRA and MRI allow excellent visualization of the
ligamentous morphology and may be helpful in the diagnostic process of carpal
sprains in dogs.
Preliminary results
