Muscle and tendon disorders Flashcards by William Hawker

What are the reported stages of muscle strain?

Stage I: myositis and bruising but architecture intact

Stage II: myositis and some tearing of the fascial sheath

Stage III: tearing of the fascial sheath, muscle fiber disruption, and hematoma formation

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What factors can impact the balance between regeneration of myofibrils and production of fibrous scar tissue?

The source of the myoblasts, an intact extracellular matrix, adequate vascularization, adequate innervation, and limited stress across the healing wound.

If the sarcolemma nuclei have survived and the endomysium is intact quick and complete repair will occur. If the sheath is damaged myofibril heads will attempt to cross the damaged area.

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What are the primary objectives of surgical muscle repair?

Maximize direct myofibril repair while minimizing the formation of scar tissue

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When should surgical rather than conservative management be recommended in patients with muscle strain?

Stage 1 and some stage 2: conservative. Consists of cold compress, NSAIDs, compression bandages. Early mobilization essential for proper myofibril orientation.

Advanced stage 2, stage 3: surgical. Debridement and direct apposition of muscle tissues (initial horizontal mattress sutures over buttons with additional appositional sutures through the fascial sheaths at the muscle ends).

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What are some reported muscle injuries of the thoracic limb?

Rupture of the origin of the long head of the triceps brachii, avulsion of the insertion of the triceps, rupture of the serratus ventralis muscle

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What are some reported muscle injuries of the pelvic limb?

Rupture of the gracilis, iliopsoas and pectineus muscle strain

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Which breed of dog is most likely to suffer from rupture of the long head of the triceps brachii, or gracilis muscle rupture?

Greyhound

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What is the treatment for rupture of the long head of the triceps brachii muscle?

Reattachment to the scapula.

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What is the treatment for avulsion of the triceps brachii tendon of insertion?

Reattachment to the olecranon. Augmentation with a synthetic graft may aid in repair. The elbow must be maintained in extension during healing (transarticular ESF, or screw between the olecranon and distal humerus).

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What is the treatment for rupture of the serratus ventralis muscle?

Conservative management or reattachment of the scapula to the thoracic wall with sutures around the rib cage.

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What is the treatment for rupture of the gracilis muscle?

Surgical repair or reattachment.

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What are the gait and stance changes commonly observed with infraspinatous contracture?

Gait: limb circumduction, flicking of the carpus.
Stance: abduction of the shoulder, adduction of the elbow, abduction of the antebrachium with external rotation

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What type of dogs are most frequently affected by infraspinatous contracture?

Medium sized working or athletic dogs.

Transient thoracic limb lameness is typically observed 4-6 weeks before onset of the physical signs of contracture.

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What is the treatment for infraspinatous contracture?

Tendenectomy of the tendon of insertion of the infraspinatous muscle

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What are the typical limb abnormalities observed with quadriceps contracture?

Leg held straight with inability to flex either the stifle or the tarsus

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What is the treatment for quadriceps contracture?

If early, aggressive physical rehabilitation can be implemented.

Surgical debridement of adhesions and lengthening of the quadriceps mechanism may be attempted, but must be followed with aggressive physical therapy.

Amputation often results.

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What is the typical signalment in cases of gracilis or semitendinosus contracture?

Middle aged German shepherds

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What is the gait abnormality in patients with gracilis or semitendinosus contracture

Affected leg is raised in a jerk-like fashion with hyperflexion of the tarsocural joint and internal rotation of the metatarsus

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Is surgical intervention recommended in instances of gracilis or semitendinosus contracture?

No, likely to recur. Condition not painful.

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How is contraction of the flexor carpi ulnaris muscle treated?

Splinting with spontaneous recovery typical within 2-3 weeks. Surgical tendenectomy can be performed if failure to resolve with conservative management

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When is surgical removal of myositis ossificans lesions recommended?

If they are causing a mechanical lameness. Often recur following removal.

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Which patients are at increased risk for myositis ossificans formation?

Patients with von Willebrands disease

What is the difference in healing between tendons with a paratenon and those that are sheathed?

Paratenon: can receive vascular buds and an influx of undifferentiated cells from the paratenon following injury. Better capacity for rapid healing (also called vascular tendons).

Sheathed: much more reliant on their intrinsic blood supply for healing

What are some examples of vascular and avascular tendons?

Vascular: tendon of gastroc and triceps.
Avascular: digital flexor tendons

How is gap formation important in tendon healing?

Presence of a gap will result in interposition of fibrous tissue and impeded healing

What is the strength of the tendon at 6-weeks post repair and 1 year post-repair?

6-weeks: 56% 1-year: 79% Tendon must be supported throughout the first 3-weeks of healing as it loses strength during this time.

What tendon suture patterns are designed for use in flat tendons?

Locking loop (Kessler), Krackow

What tendon suture patterns are designed for use in round tendons?

Three loop pulley

How long should a tendon be protected following surgical repair?

At least the first 3 weeks (bandages, casts, transarticular screws, or transarticular ESF). After 3 weeks some loading is useful to ensure development of correct alignment of collagen within the tendon.

If injury to the digital flexor tendons occurs below the separation of the tendon into individual digital slips, how many individual tendons will require repair in cases of laceration?

Eight (4 superficial, and 4 deep). Repair should be augmented with a flexion bandage for 3-weeks, followed by a bandage in a normal weight bearing position for an additional 3 weeks.

What is a common sequelae of failure to repair the deep flexor tendons following injury?

Decubital ulcers of the metacarpal or metatarsal pads. Flattened digits.

Which breed of dog is most commonly affected by medial displacement of the tendon of origin of the biceps brachii muscle?

Racing greyhounds

How is medial displacement of the tendon of origin of the biceps brachii muscle surgically treated?

Surgical replacement or repair of the transverse humeral retinaculum. If repair not possible tendon can be transected and reattached to the proximal portion of the humerus.

What is the prognosis for surgical treatment of medial displacement of the tendon of origin of the biceps brachii muscle surgically treated?

Fair to good

What is the surgical treatment for avulsion of the long digital extensor tendon?

Reattachment using a screw and washer, or resection (if chronic) and reattachment to the proximolateral tibia

What is the most likely signalment for a patient with avulsion of the long digital extensor tendon?

Immature large breed dogs

What is the treatment for displacement of the long digital extensor tendon?

Small bridge of suture across the extensor groove

In a study by Duffy 2019 in Vet Surg, did the addition of epitendinous sutures to either a 3-loop pulley or locking loop repair of the superficial digital flexor tendon result in increased strength and resistance to gap formation?

Yes. The 3-loop pulley was also stronger than the locking loop repair when used alone.

According to Duffy 2020 in Vet surg, what autologous structure may be useful in augmenting 3-loop pulley repair of a lacerated gastrocnemius tendon? What autologous structure was used by Duffy 2021 in Vet Surg?

Lateral digital flexor. Increased failure forces by 2 fold, eliminated 1 and 3mm gap formation, with 85% of augmented structures failing at the myotendinous junction. In 2021 Duffy described use of an accessory tendon (common tendon of the gracilis, biceps femoris and semitendinosis) graft. Increased failure forces by approximately 2x.

According to Duffy 2020 in Vet surg, which epitendinous suture pattern(s) was associated with the highest mean yield, peak and failure loads when combined with a core locking loop for repair of the superficial digital flexor tendon? 1) Partial circumferential epitendinous suture (180 degrees on the palmar side) 2) 360 degree ES with double knot technique 3) 360 degree ES with single knot

Circumferential patterns had increased yield, peak, and failure loads as compared to partial circumferential suturing.

According to Eby 2020 in Vet Surg, which epitendinous suture pattern(s) were associated with the highest yield, peak and failure loads when used to augment locking loop repair of the superficial digital flexor tendon? 1) No ES 2) Smooth ES 3) Vloc ES 4) Quill ES 5) Stratafix ES

All ES outperformed no ES. Stratafix performed better than other barbed sutures and was equivalent to monofilament ES.

In a study by Duffy 2021 in Vet Surg, was there a biomechanical difference between 3-loop pulley constructs and a novel barbed suture pattern augmented with epitendinous sutures for repair of the superficial digital flexor tendon?

No difference between barbed and 3-loop locking suture, although use of epitendinous sutures in both groups increased failure loads by 80%.

According to Chiu 2021 in Vet Surg, which 3 novel suture patterns outperformed a 3-loop pulley pattern for repair of superficial digital flexor tendons?

Exposed double cross lock, embedded double cross lock, modified tang.

In a study by McKay 2023 in Vet Surg, which of the following constructs used to augment patellar tendon repair with a locking loop and epitendinous suture was the most biomechanically stable? 1) Transpatellar TBW 2) Suprapatellar TBW 3) Combined TBW

Combined TBW. Increased yield, peak and failure loads.

In a study by Wilson 2023 in JAVMA, was there a suspected inherited familial risk for fibrotic myopathy in the German shepherd?

Yes - pedigree analysis supported an inherited familial risk. Males were overrepresented.

In a study by Abbey 2021 in JSAP, what was the rate of mineralization of the supraspinatous tendon in non-lame dogs?

4% (suggests that mineralization may be associated with thoracic limb lameness when identified)

In a study by Jury 2021 in JSAP, what technique was used successfully in the repair of luxation of the superficial digital flexor tendon? In what direction was the luxation most frequently observed?

Primary repair of the medial retinaculum, lateral retinacular release with placement of a k-wire into the lateral process of the calcaneal tuberosity (see image). Lateral luxation was observed in all cases expect for 1 case of medial luxation. Shetland sheepdogs were overrepresented. No post-operative immobilization was used and all cases returned pre-injury level of activity.

In a study by Goh 2022 in JSAP, what percentage of dogs undergoing surgical repair of a superficial digital flexor tendon luxation suffered re-luxation? What increased the risk of surgical failure? Did limb immobilization for longer than 6-weeks significantly affect the surgical outcome?

15% had reluxation, with 13% having a persistent lameness despite no re-luxation. Use of absorbable rather than non-absorbable suture increased the risk of failure by 60%. Surgical failure was also more common in cases managed with non-rigid immobilization post-op. Limb immobilization for longer than 6 weeks was not associated with increased success as compared to shorter periods of immobilization.

In a study by Cocca 2020 in VCOT, did the addition of an interlocking horizontal mattress epitendinous suture pattern increase the yield, failure forces, and occurrence of 3mm gap formation in a canine common calcaneal laceration model?

Yes - loads at yield, peak and failure were all increased by 2 times, and gap formation was significantly reduced.

In a study by Baroncelli 2021 in VCOT, what technique was used to immobilize the tarsocrural joint after surgical repair of rupture of the common calcaneal tendon?

Calcaneotibial locking plate (no major complications). The approach is indicated in the attached image.

In a study by Curcillo 2021 in VCOT, which of the following multi-strand repair techniques for repair of a gastrocnemius tendon had the highest strength and least gap formation? 1) Two strand 2) Four strand 3) Six strand

Six strand

In a study by O'Byrne 2022 in VCOT, was a 3- or 4-loop pulley suture pattern biomechanically superior in repair of a cadaveric canine gastrocnemius tendon? Which pattern resulted in less gap formation?

The 4-loop pulley was biomechanically superior and required a greater load for 1mm and 3mm gap formation.

In a study by Haubler 2023 in JFMS, were injuries to the feline calcaneal tendon more commonly closed or open? What Meutstege classification was most common? In a follow-up study by the same author what percentage of cats were treated surgical for CCT injury? What two methods of post-operative tarsal joint immobilization were most commonly used? What was the most common short-term minor complication? What percentage of cats were free of lameness at long term evaluation?

Closed injuries were most common (70%). 32% of injuries were atraumatic, and 38% were traumatic. Increasing age increased the risk of atraumatic injury. Meutstege type IIc injuries were most common (see image). Although acute injuries were more likely to be Meutstege type I. 83% of cats were surgically treated. The two most common methods of stabilization were transarticular ESF (57%) or calcaneotibial screw (33%). The most common short term complication were pin tract infections related to the transarticular ESF. 86% of cats were free of lameness at long term follow-up.

What suture technique for repair of common calcaneal tendon rupture is depicted as described in Schulz 2019 in Vet Surg?

Loop suture pattern with FiberWire, secured in the calcaneus with a bone tunnel.