Chapter 88 - Flexural Limb Deformities Flashcards
Flexural Deformities plane
Occur in the sagittal plane
Flexural Deformities affected primarly bones or soft tissues?
Affect primarily soft tissues
Angular Limb Deformities plane
Occur in the frontal plane
Angular Limb Deformities affected primarly bones or soft tissues?
Affect primarily osseous
structures
Angular Limb Deformities treatment»
Many can initially be treated
conservatively
Flexural Deformities require imaging?
Rarely require imaging/
radiography vs angular that require radiography
Flexural Deformities treatment?
Most need immediate
conservative treatment
Flexural Deformities the farrier treatment is applied where?
Farriery is applied to the toe
or heel
Angular Limb Deformities the farrier treatment is applied where?
Farriery is applied medially
or laterally
Describe flexural deformities in horses.
They are joint abnormalities where joints are held in flexed or extended positions.
How do flexural deformities differ from angular limb deformities?
Flexural deformities affect the joint’s flexion, while angular deformities affect the alignment.
Why is the term “contracted tendons” considered incorrect for persistent hyperflexion?
Tendons are usually functionally too short rather than actually contracted.
Under what conditions do tendon contractions typically occur in horses?
After tendon injuries, often seen in adults but rarely in foals.
How are flexural deformities typically named in veterinary practice?
According to the joint involved, not the tendon.
Which limbs are more commonly affected by flexural deformities?
The forelimbs.
What is the primary difference between congenital and acquired flexural deformities?
Congenital deformities are present at birth; acquired ones develop later.
Which joints are most commonly affected by congenital flexural deformities?
The metacarpophalangeal (MCP) and carpal regions.
In which specific cases is congenital lateral luxation of the patella relevant to flexural deformities?
It can cause functional flexural deformity of the stifle.
Name two joints most frequently affected by acquired flexural deformities.
The distal interphalangeal (DIP) and MCP joints.
What factors are proposed as potential causes of congenital flexural deformities?
Intrauterine malpositioning, diseases in pregnant mares, genetic factors.
Explain the intrauterine malpositioning hypothesis in the context of congenital flexural deformities.
Crowding in the uterus, especially in large foals, can lead to deformities.
What was the observed incidence of limb contractures in fetuses and newborn foals submitted for necropsy?
20% of cases.
List any two diseases or conditions in mares that can potentially lead to flexural deformities in foals.
Locoweed ingestion and equine goiter.
How are digital hyperextension deformities in newborn foals typically caused?
By flaccidity of the flexor muscles.
Describe the symptoms of mild digital hyperextension in foals.
Foals cannot maintain toes on the ground and have acutely angled MCP or MTP joints.
Why is it generally unnecessary to perform radiographic evaluations for digital hyperextension deformities?
No abnormalities are usually found.
What are the potential complications of severe digital hyperextension deformities in foal
Skin lesions due to trauma.
What impact can severe congenital flexural deformities have on the birthing process?
They can cause dystocia (difficult birth).
How can flexural deformities be managed if identified soon after birth?
With splints or casts within 30-45 minutes.
What action should be taken if a flexural deformity is not responsive to conservative therapy?
Use splints, medical treatment, or both.
Why might radiographs be necessary in cases of severe MCP/MTP flexural deformities?
To rule out abnormal bone formations that worsen prognosis.
Describe a mild carpal flexural deformity in foals.
The foal can stand but cannot fully straighten the carpi.
What is typically the prognosis for MCP/MTP flexural deformities if there are no osseous changes?
The prognosis is good for all severity levels.
How does the inability to manually straighten the carpus affect the prognosis for a carpal flexural deformity?
Prognosis is guarded if the carpus cannot be straightened.
Why are congenital PIP joint flexural deformities rarely reported?
They often involve osseous and soft tissue abnormalities.
What is a common cause of congenital tarsal flexural deformities?
Incomplete ossification of the tarsal bones.
Why is early radiography crucial for congenital tarsal flexural deformities?
To prevent irreversible bone damage.
Identify the anatomical area affected in foals with a ruptured common digital extensor tendon.
The dorsolateral aspect of the carpus.
Explain the walking posture of a foal with a ruptured common digital extensor tendon.
The foal throws forelimbs forward, extends, retracts, and may knuckle at the MCP joint.
Why might a ruptured common digital extensor tendon be misclassified as a flexural deformity?
It appears as a flexural deformity but lacks tendon support.
Describe the knuckling behavior observed in foals with a ruptured common digital extensor tendon.
They knuckle at the MCP joint when walking.
Why are radiographs often unnecessary for diagnosing flexural deformities?
They are generally diagnosed based on clinical signs.
How can incomplete ossification of certain bones complicate the prognosis for flexural deformities?
It can be associated with angular and flexural deformities.
What role does cross-linking of elastin and collagen play in flexural deformities?
Defects in cross-linking are associated with deformity development.
What treatment is recommended for foals with incomplete ossification of cuboidal bones?
Stall rest until ossification is complete.
What symptoms would indicate that radiographic evaluation is necessary for flexural deformities?
Severe deformity or suspected abnormal bone formation.
How do radiographic findings affect the management of flexural deformities?
They help identify osseous abnormalities impacting prognosis.
Why is excessive exercise contraindicated for foals with digital hyperextension deformities?
Fatigue may aggravate the problem.
What immediate action is required for severe digital hyperextension deformities?
Prompt treatment to prevent necrosis and skin excoriation.
What type of shoe might help foals with severe digital hyperextension?
Glue-on shoes or extensions with palmar/plantar support.
Why are analgesics typically unnecessary for digital hyperextension deformities?
Pain is usually minimal or absent.
When might toe trimming or rasping be unnecessary in treating digital hyperextension?
In mild cases where the condition self-corrects.
Why should adhesives be used cautiously in foals younger than 3 weeks?
To avoid heat trauma to delicate feet.
What risk is associated with leaving toe extensions on too long?
Constriction and deformation of the foot.
Why is light bandaging recommended for foals walking on the back of their pasterns?
To minimize skin trauma without fully supporting the limb.
What is the consequence of using splint bandages or casts on foals with digital hyperextension?
Loss of tone in flexor tendon units and risk of pressure sores.
Why might padding be applied over braces on the foot for digital hyperextension?
To protect the palmar/plantar region and reduce hyperextension.
Why is tenoplasty generally not recommended for foals with digital hyperextension?
It’s not favored in small or miniature foals with the condition.
What initial non-surgical approach can help treat congenital flexural deformities?
Moderate exercise without overtiring.
How does overexertion affect foals with carpal flexural deformities?
It leads to muscular fatigue and worsens the deformity.
What drug is commonly used for congenital flexural deformities?
Oxytetracycline administered intravenously.
How quickly can deformities correct after oxytetracycline administration?
Within 24 to 48 hours in young foals.
What is the hypothesized mechanism of oxytetracycline in treating flexural deformities?
Inhibition of collagen gel contraction and MMP-1 reduction in myofibroblasts.
What serious side effect of oxytetracycline has been reported?
Acute renal failure in a foal, treated with hemodialysis.
Which NSAID is often prescribed for flexural deformities pain?
Phenylbutazone or flunixin meglumine.
What precaution should accompany NSAID use in foals?
Use of gastric protectants like omeprazole or ranitidine.
How do toe extensions help foals with flexural deformities?
They delay breakover and increase tensile forces in flexor tendons.
What might happen if toe extensions aren’t braced back properly?
It could cause distraction, infection, and separation of the hoof wall.
Why is acrylic useful for securing toe extensions?
It interdigitates with the dorsal hoof wall, adding stability.
What typically occurs two weeks after applying dorsal extensions for mild DIP deformities?
The extensions are removed or detach as the deformity corrects.
Why are half-limb casts beneficial for DIP joint flexural deformities?
They immobilize and relax musculotendinous units.
What is the main limitation of splints compared to casts?
Splints may move and create pressure sores if not secured well.
What are some materials used to make splints?
PVC, wood, thermoplastic, fiberglass.
What potential complications arise with improperly applied splints?
Pressure sores or even distal limb necrosis.
How often should splints be reset in foals with flexural deformities?
Daily, to examine for rubbing or other complications.
What drug class is useful for sedation during splint application?
α2-Adrenoreceptor agonists (e.g., xylazine or detomidine).
What analgesic combination might be used for newborns in splinting?
Midazolam or diazepam with an opioid for pain control.
Why should α2 agonists be avoided in foals under 2 months?
Due to undesirable respiratory and cardiovascular effects.
Why might splints be preferred over casts for mild carpal flexural deformities?
hey provide adequate support without full immobilization.
What condition might foals with MCP/MTP joint deformities and lax tendons require?
Splinting that avoids incorporating the foot.
Why is padding important when applying splints?
To protect skin from excoriation and avoid rotation of the splint.
Why is regular padding replacement essential in splinted foals?
To reduce the risk of pressure sores.
What should be done if a splinted foal can’t rise and nurse independently?
Assist them until they can stand unaided.
Why might anti-inflammatory drugs be needed in tendon stretching procedures?
To manage pain from soft tissue and joint capsule stretching.
Surgical treatment is most commonly carried out for________flexural deformities
Surgical treatment is most commonly carried out for carpal flexural deformities
What material should be used to make custom-fitted splints?
Casting materials or thermoplastic shaped to the limb’s contour.
Describe the surgical technique for carpal flexural deformity
GA - LR or DR (if billateral) - limb uppermost - 3- to 5-cm-long lateral skin incision is made just proximal to the accessory carpal bone. The tendons of insertion of the ulnaris lateralis and flexor carpi ulnaris are identified deep to the fascia, isolated by blunt dissection and transected approximately 2 cm proximal to the accessory carpal bone. If these tendons are the structures preventing extension of the carpus, once they have been transected surgically, the limb can be manually straightened. Routine closure of subcutis and skin is performed; a vertical incision is made over the lateral aspect of the accessory carpal bone and the tendons identified deep to the fascia. It is advisable to manipulate the limb immediately before surgery, while the foal is under anesthesia, to ascertain if these tendons tighten when forceful carpal extension is applied.
Figure 88-9. The same foal as in Figure 88-8. Because of a lack of extensor support, the foal was unable to walk without stumbling. Application of a distal limb splint improved the foal’s ability to walk and support weight on the limb.
Figure 88-10. (A) A newborn foal with marked digital hyperextension in the hindlimbs. (B) The same foal immediately after application of a pair of Dallmer glue-on shoes. A clear plastic wrap (not shown) is used to ensure good contact between shoe and hoof during the hardening process of the polymethyl methacrylate (PMMA). Note the ability of the foal to bear weight on the soles after shoe application.
Figure 88-13. A foal with flexural deformities of both carpi, which were treated with application of splints, oxytetracycline, and analgesics. Because both forelimbs were splinted, the foal required assistance to stand but could walk in the splints unaided once it was upright.
Figure 88-11. Application of metal plantar extensions in a standing sedated foal with a severe digital hyperextension in the hind feet. The metal strips are curved over the toe and secured to the foot with acrylic.
Figure 88-12. A foal with marked digital hyperextension shod with metal palmar extensions, which have been covered with padding and elastic bandage to provide additional protection to the palmar pasterns and to prevent injury to the mare and foal from the metal extensions
Figure 88-14. A PMMA toe extension applied to a foal following a desmotomy of the accessory ligament of the deep digital flexor tendon for treatment of a flexural deformity of the distal interphalangeal joint. The toe extension stretched the deep digital flexor musculotendinous unit, and by filling the gap between the toe extension and the dorsal hoof wall with acrylic, the distraction forces between the hoof wall and the underlying laminae are neutralized.
Figure 88-16. A custom-made splint for a foal with a flexural deformity of the MCP region. The splint has been made using the normal MCP region as a template and is now ready to be placed on the limb with a flexural deformity. The extent of the deformity can be seen as the disparity between the splint and the affected limb.
Figure 88-17. A foal with a severe flexural deformity in the carpal region, which was unresponsive to treatment.
Figure 88-18. A stage I flexural deformity of the DIP joint. Note that the dorsal hoof wall has not passed the vertical and that the distodorsal tip of the hoof wall has flared from the forces caused by the abnormal foot position.
Figure 88-3. A newborn foal with mild digital hyperextension. Note the skin over the heel bulbs is in contact with the ground; the skin must be protected from excoriation.
Figure 88-1. A congenital flexural deformity of the stifle caused by lateral luxation of the patella secondary to hypoplasia of the trochlear groove.
Figure 88-4. A premature foal showing severe digital hyperextension. The foal responded quickly to restricted exercise.
Figure 88-5. A congenital flexural deformity of the MTP joint. The foal responded to splinting, oxytetracycline administration, and analgesics
Figure 88-6. (A) A marked bilateral flexural deformity of the carpi. The foal is unable to completely straighten the limbs. (B) The foal 8 weeks after treatment with tube casts for 4 days.
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Figure 88-8. Rupture of the common digital extensor tendon in the right forelimb of a young foal, which can create the appearance of a flexural deformity. Note the characteristic bulge over the dorsolateral aspect of the carpus. The foal also has a moderate carpal valgus deformity in the left forelimb.
Figure 88-7. (A) Lateromedial (LM) radiographic view of a newborn foal with an anomaly of the proximal MTIII. The small tarsal bones have not been irretrievable damaged. The foal was treated with exercise restriction. (B) The same foal as a yearling with acceptably normal radiographs.
Figure 88-6. (A) A marked bilateral flexural deformity of the carpi. The foal is unable to completely straighten the limbs. (B) The foal 8 weeks after treatment with tube casts for 4 days.
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Figure 88-4. A premature foal showing severe digital hyperextension. The foal responded quickly to restricted exercise.
Figure 88-3. A newborn foal with mild digital hyperextension. Note the skin over the heel bulbs is in contact with the ground; the skin must be protected from excoriation.
Figure 88-15. (A) A 4-month-old foal with a stage I flexural deformity in the DIP joint. The hoof wall is flared and cracked and bruising of the wall is evident; (B) The same foal after trimming of the foot with removal of excess heel and removal of the broken hoof at the toe. Note the foal cannot place the heel to the ground; (C) The foal after application of an acrylic toe extension; the foal can now place the heel to the ground. (
Figure 88-21. Surgical technique of desmotomy of the ALDDFT (inferior check ligament desmotomy). (A) Location of the surgical site on the medial, or in most cases the lateral, side of the limb (dotted line). (B) The paratenon enclosing the deep flexor tendon and the accessory ligament is incised. (C) The accessory ligament is isolated along its division plane with the deep digital flexor tendon. a, Musculus interosseus (suspensory ligament); b, accessory ligament of the deep digital flexor tendon; c, deep digital flexor tendon; d, superficial digital flexor tendon. (D) The isolated and elevated accessory ligament is transected along the dotted line.
Figure 88-22. A toe extension incorporated into a shoe for treatment of an acquired flexural deformity of the MCP joint.
Figure 88-23. Surgical technique of ALSDFT (superior check ligament desmotomy). (A) Location of the surgical site relative to the anatomic landmarks: cephalic vein, distal radial physis, and chestnut. (B) The tendon sheath of the flexor carpi radialis muscle is incised. (C) The flexor carpi radialis tendon is retracted, allowing visualization of the craniolateral tendon sheath wall. The site of the desmotomy incision is marked with a dotted line over the accessory ligament, which is at this location part of the craniolateral tendon sheath wall. (D) The accessory ligament desmotomy is completed, allowing digital access to the radial head of the deep digital flexor muscle. (
