70.Muscle_tendon_Dz Flashcards
what is the most common type of muscle-tendon injury
STRAIN or overstretchingusually occurs at the myotendinous unit/junctionoccurs when active contraction and passive extension occur simultaneouslymuscles that cross >2 joints are more prone to injury
three stages of muscle strain
- myositis and bruising2. myositis with mild tearing3. tearing of the fascial sheath with muscle fiber disruption
two ways muscles heal
- direct regeneration of myofibril (as long as sarcolemma survived insult and if endomysium is intact)2. fibrous scar tissue production
surgery management of muscle stage 2 or 3 damage with tearing
–recommended for more severe injuries to appose the muscle and limit scar formation–surgery should take place once initial inflammation has receded (2-3 days)–evacuate/debride hematoma–long lasting monofilament absorbable suture–horizontal mattresses to oppose (use FASCIA and buttons/stents); can augment with additional sutures in apposition
excessive scar tissue in muscle can reduce its function by how much
50%
muscle tendon injury common in greyhound
avulsions/rupture of long head of triceps—can feel depression caudal and distal to scapulaalso see rupture of gracilius muscle
what muscle must be damaged when a scapular displacement is seen
serratus ventralis muscle
ruptured gracilus muscle
Greyhound, German shepherd, Foxhound
most common muscles presenting with strain injury
iliopsoas (attaches to lesser trochanter)pain on direct palpation and hip extension/internal rotation25% iliopsoas and pectineus involved
define muscle contracture
abnormal shortening of tissue rendering the muscle highly resistant to stretch–infraspinatus–quadriceps–gracilis/semitendinosus-flexor carpi ulnaris
characteristic of infraspinatus muscle contracture
elbow adducted, forelimb abduction and externally rotatedcircumduction of limb during walkatrophy over the shoulderunilateral; biphasic lamenesstendinectomy along with release from fibrotic tissue
quadriceps femoris muscle contracture
devastating consequence of femora fx in young dogs without rehab (stifle flexion)with contracture flexion is loss, stifle and tarsus is extendedprevention is key bc surgical correction has limited success
gracilus and semitendinosus muscle contracture
German Shepherd dogjerk like raised affect leg with hyper flexion of tarsocrucal joint and internal rotation of metatarsusNOT painful
flexor carpi ulnaris contracture
flexure deformity of puppies (or carpal hypo extension)bilateraltendon is palpably tightreversible with time +/- splints
tendon healing
SLOW depends on influx of new fibroblasts to produce new collagen
difference btwn sheathed and unsheathed or paratenon tendons and healing
paratenon (unsheathed) obtain vascular supply and source of cells from surrounding tissues; heal more rapidly; also termed vascular tendons: GASTROCNEMIUS, TRICEPSsheathed tendons are avascular; depend mush more on intrinsic blood supply for healing; also want minimal gap to minimize scar: DIGITAL FLEXOR TENDONS
how much strength does a tendon have after suture repair (6 weeks post op)
at 6 weeks post op tendon only has 56% original strengthwill slowly increase to about 80% at a year post opnormal muscle contraction puts only 25-33% strain on tendons therefore strength at 6 weeks is sufficient for activity
principles of tendon repair
- restore Fx (tensile strength) and gliding function2. minimize gap/scar formation potential3. minimize debridement to maintain normal working length of tendon4. do NOT place incision onto of tendon (scar may form near tendon); keep incision parallel to tendon5. minimize crush handling of tendon (use small pins, needles to manipulate)6. monofilament nonabsorbable or long lasting absorbable7. minimize tension on tendon by extending/flexing nearby joints8. tendon suture patterns for approximation of tendon ends9. +/- augmentation with appositional suture around tendon with smaller size10. immobilization at least 3 weeks (bandage-cast,splint, transarticular screw, transarticular ESF)
tendon suture patterns
- locking loop (Kessler)-flat2. Bunnel3. F-N-N-F4. three loop pulley—round (increased resistance to pullout)5. continuous cruciate pattern–flat6. Krackow –flat
common mistake for repair of severed digital flexor tendons
mistake is to only repair to superficial part of the tendon and missing the deep part of the digital flexor tendonsanimal wear bear weight on metatarsal/carpal pad –chronically lame with soresthere should be 4 deep and 4 superficial requiring repairflexion bandage (NWB and rids tension on tendons) 3 weeks; Normal bandage additional 3 weeks
injuries to the tendon of origin of the biceps brachii muscle
O: supraglenoid tubercle avulsion or ruptureor medial displacement of tendon because of transverse humeral ligament rupturesurgery: tenodesis and/or repair of transverse humeral ligament
injury to the long digital extensor tendon
avulsion off of the lateral aspect of the distal femur in immature large breed dogsor displacement from extensor groovetenodesis, reattachment of avulsed piece, or suture across the extensor groove to keep from displacement
