Lecture 34 4/15/25 Flashcards
What is the anatomy of the tendon?
-dense band of fibrous connective tissue
-contains thick, closely packed parallel bundles of longitudinally oriented collagen
-tenoblasts are arranged in long parallel rows in the spaces between collagenous bundles
What is the primary tendon bundle?
coherent bundles of collagenous fibrils lying between rows of fibroblasts and encircled by their anastomosing processes
What are primary tendon bundles grouped into?
fascicles/secondary bundles
What are fascicles grouped into?
tertiary bundles
How long does it take for a tendon to renew all of its collagen?
6 months
What are the characteristics of the endotenon?
-lies between the tendon bundles
-carries vessels, nerves, and lymphatics
-an extension of the epitenon
What are the characteristics of the paratenon?
-elastic and pliable
-long fibers to allow tendon to move back and forth
-encloses the tendon outside of the epitenon
-not present when there is a tendon sheath
What are the characteristics of the tendon sheath?
-comparable to a joint capsule
-has outer fibrous sheath and inner synovial membrane
-synovial membrane folds around tendon to create visceral and parietal layers that are continuous along the mesotenon fold
What are annular ligaments/retinacula?
strong fibrous bands that act to maintain the tendon in its correct position
What are the 4 sources from which tendons can receive blood?
-the muscle to which it is attached
-the bone to which it is attached
-a mesotendon or vinculum within a synovial sheath
-the paratenon if no sheath exists
Which portions of the tendon can the muscle and bone supply with blood?
the proximal and distal 25% of the tendon (middle 50% needs other sources)
What are the mechanical properties of tendons?
-possess great tensile strength
-have low extensibility
-serve primarily as a force transmitter
-dynamic amplifier during rapid muscle contraction
-elastic energy store
-force attenuator during rapid and unexpected movement
-exhibit both an elastic phase and visco-elastic phase during stress
What are the characteristics of tendon healing?
-tendons undergo both intrinsic and extrinsic healing
-tendons without a blood supply will heal via intrinsic method; endotenon cells function as active fibroblasts
-nearly all tendon healing occurs via extrinsic method
-peritendinous tissue is disrupted and healing proceeds via classic wound healing phases
-vessel ingrowth from surrounding tissues is vital to extrinsic method
Why is it important to engage in early passive loading of tendons during healing?
-major disadvantage of extrinsic healing is the development of adhesions
-passive loading allows collagen fibers to orient along lines of stress
-passive loading decreases adhesion formation
What are the characteristics of tendinitis/bowed tendon?
-occurs secondarily to overloading, excessive external pressure, or external bow
-classified as high, mid, or low bow depending on location
-may involve SDF, DDF, or both
-diagnosis based on clinical signs and ultrasound
What are the key aspects of treatment for acute tendinitis?
-reduce inflammation
-support injured limb
What are the characteristics of surgical correction for chronic tendinitis?
-tendinitis of the SDF tendon may be treated with both superior check ligament desmotomy and tendon splitting
-tendinitis of the DDF tendon likely to be treated with just tendon splitting, but can do an inferior check ligament desmotomy if indicated
What are the medical therapy options for chronic tendinitis?
-shockwave therapy
-stem cells
-bone marrow
-platelet rich plasma
What should the follow up care be for surgical or medical treatment of tendinitis?
-controlled exercise
-monitoring of lesions with ultrasound and adjusting exercise accordingly
What are the characteristics of treatment for traumatic division of a flexor tendon?
-tendon ends should be reunited as soon as possible
-want to use a triple locking loop or three-loop pulley
-suture material should be inert, non-reactive, and large in size
-limb should be cast for 28 days
-after casting limb should be heavily bandaged and passive loading begun
-external coaptation and wound management indicated for large deficits
-may need extended heel shoe
What are the characteristics of treatment for traumatic division of digital extensor tendons?
-good prognosis with treatment
-cast or bandage in normal extension
-healing via granulation with excellent compensation
-may need extended toe shoe to prevent fetlock knuckling
What are the characteristics of acquired contracture?
-usually unilateral
-result of prolonged decreased weight bearing
-DDF tendon usually involved
-can also have a bilateral forelimb SDF tendon contracture; most common in rapidly growing horses around 2 years old
What are the characteristics of acquired contracture therapy?
-depends on the tendon involved
-conservative therapy may be possible in early cases
-surgical intervention includes superior and/or inferior check ligament desmotomy
-severe causes require tenotomy of involved tendons
-suspensory ligament and caudal joint capsule may be involved in chronic cases
What are the characteristics of tenosynovitis?
-distention of tendon sheath that is usually a reaction to hard work
-usually not accompanied by heat or pain
-more often the result of chronic insult to the tendon sheath
-insult causes a transient over-production and/or decreased absorption of synovial fluid
What are the common sites of tenosynovitis?
-digital flexor sheath at the level of the fetlock
-extensor tendon sheaths on anterior aspect of carpus
-deep digital flexor sheath at level of the tarsus
How is tenosynovitis diagnosed?
-visual appearance
-palpation
-ultrasound
What are the characteristics of tenosynovitis treatment and prognosis?
*synovial distention options:
-rest, wraps and hydrotherapy
-drain and wrap
-drain, inject steroids, and wrap
*fibrous distention option:
-heat and therapeutic ultrasound
*prognosis:
-good to grave if septic
What are the characteristics of ligaments?
-similar to tendons in structure, function, and physiology
-ligaments run from bony origin to bony insertion without incorporation of muscle mass
-usually injured by one or more severe traumatic incidences
What are the important conditions that affect the ligaments?
-suspensory ligament desmitis (mid to distal or proximal)
-check ligament desmitis
-distal sesamoidean ligament desmitis
What are the characteristics of suspensory ligament desmitis in the forelimb?
-occurs most often in trotters and pacers
-gait specific malady
-seen in gaited horses and thoroughbreds as well
-one acute misstep or overreaching incident may initiate a desmitis
How is suspensory ligament desmitis in the forelimb diagnosed?
-visual
-palpation
-nerve blocks/local infiltration
-radiographs
-ultrasound
-MRI (gold standard
What are the treatment options for acute suspensory ligament desmitis in the forelimb?
-rest
-hydrotherapy
-butazolidin
-wraps
What are the treatment options for chronic suspensory ligament desmitis in the forelimb?
-heat
-soaks
-ultrasound
-injectable sclerotics (old therapy)
-surgery
-shockwave therapy
-stem cells or platelet rich plasma
What are the characteristics of suspensory desmitis in the rear limb?
-seen most frequently in performance horses that use rear end
-frequently misdiagnosed as bone spavin/arthritis
-usually a chronic problem that improves with rest before worsening with work again
-primarily involves proximal suspensory
How is suspensory desmitis in the rear limb diagnosed?
-diagnostic nerve blocks
-ultrasound
-radiographs
-scintigraphy
-MRI (gold standard)
What are the medical treatment options for suspensory desmitis in the rear limb?
-prolonged rest
-stem cells or platelet rich plasma
-shockwave therapy
What is the surgical treatment for suspensory desmitis in the rear limb?
neurectomy of the deep branch of the lateral plantar nerve
What is the prognosis for suspensory desmitis in the rear limb?
-guarded to poor with just rest
-fair with shockwave therapy
-fair to good with neurectomy or regenerative medicine
What is the cause of check ligament desmitis?
-though to occur due to overextension of carpus and/or fetlock
How is check ligament desmitis diagnosed?
-ruling out all other lower limb lameness causes
-palpation of check ligament
-local infiltration of anesthetic
-radiographs
-ultrasound
What are the treatment options for check ligament desmitis?
*acute:
-rest
-local steroids
*chronic:
-rest
-shockwave
*all:
-regenerative medicine
What are the characteristics of distal sesamoidean ligament desmitis?
-involves a group of three separate sets of compact, strong ligaments that anchor proximal sesamoid bones at level of fetlock
-ligament groups are short/cruciate, oblique, and straight
-ligaments typically only injured via direct trauma
-overstressing of this region usually manifests as a sesamoid fracture or suspensory desmitis
-very serious injury best treated with regenerative medicine and extended rest
-ultrasound good for dx; MRI gold standard
-prognosis for normal function is guarded
