Tendon and Ligament Injury Diagnosis and Treatment

Approaches to Tendon & Ligament Disease

• Presented by Jodie Daglish, BVSC MS DACVSMR MRCVS, equine sports medicine and rehabilitation clinician
• At Newmarket Equine Hospital (NEH)

Tendons and Ligaments - Learning Objectives

• Construct a differential diagnosis list based on clinical presentations associated with tendon and ligament lesions
• Select appropriate diagnostics to confirm the lesion
• Select appropriate medical, surgical and complementary treatments of the specific lesion
• Determine appropriate prognosis for the specific lesion

How to Approach a Tendon or Ligament Injury

• Determine location and severity: the function of the structure, how this has changed with injury, constituent parts, how injury affects them, and how they heal
• Restore or improve function

Injury Diagnosis

• History: Obtain a comprehensive history
• Clinical Exam: Palpation (systematic and thorough), Dynamic exam (straight line walk and trot, circles, discipline-specific exam, flexion tests/system perturbation)
• Ancillary Tests: Diagnostic analgesia (regional nerve vs. intra-synovial blocks)
• Diagnostic Imaging: Determine the "Gold Standard"

Injury Diagnosis - Palpation Findings

• Heat
• Sensitivity to digital pressure
• Swelling or thickening (focal or diffuse)
• Loss of definition of the margins of the structure
• Reduced ROM
• +/- Synovial distension

Injury Diagnosis - Dynamic Exam Findings

• Variable severity of lameness
• Mild with desmopathy
• Moderate with tendonitis, enthesopathy
• Moderate to severe with partial to complete ligament or tendon rupture
• Positive to flexion of the affected joint

Diagnostic Imaging of Soft Tissues

• Various imaging modalities are shown (e.g., radiographs, ultrasound, MRI)
• The presentation highlights the choice of imaging based on the specific clinical presentation

Injury Diagnoses - Common Soft Tissue Injuries

• Canine Front Limb: Biceps tendon, Supraspinatus tendon, Collateral ligament of the elbow, Digital flexor tendons, Flexor carpi ulnaris
• Canine Hind Limb: Cranial cruciate ligament, Gastrocnmeius +/- Common calcaneal tendon, Digital flexor tendons
• Equine Front Limb: Superficial digital flexor tendon, Deep digital flexor tendon, ALDDFT/Inferior Check Ligament, Proximal suspensory ligament, Suspensory ligament branches
• Equine Hind Limb: Proximal suspensory ligament, Medial cranial meniscotibial ligament, Suspensory ligament branches

Injury Diagnosis - Why Injuries Occur at Predilection Sites

• Degeneration: Progressive weakening due to ECM synthesis imbalances, Mechanical overuse (micro-injuries)
• Trauma: Sudden overloading, External injury

Tendon Lesion Types

• Core lesions
• Margin tears or flaps
• Fibrillation
• Avulsions/Ruptures
• Adhesions/Contractures

Ligament Lesion Types

• Strains
• Enthesopathy
• Desmopathy (sprain)
• Avulsions (partial or complete rupture)

Normal Tendon Structure and Function

• Tenocytes (fibroblasts): Arranged linearly in parallel between collagen bundles/fibres. Improved arrangement with skeletal maturation, declines with age
• Water (66%): Contributes to the tendon's structure
• Extracellular Matrix (33%): Collagen Type I (mostly, 80% dry weight), Proteoglycans (1-5%), Elastin (2%)
• Inorganic (0.2%): Minerals contribute

Normal Tendon Structure and Function (Continued)

• Diameter varies by structure (from 1.5 nm collagen molecule to 15 mm whole tendon)
• Hierarchical arrangement of collagen. Crimp and inter-fascicular tenocytes
• Tendons transmit forces between muscle and bone (mainly tensile; highest tensile strength 17x body weight)
• Compressive regions (e.g., point of hock, sites of sesamoid bones)
• Functions: concentrate muscle forces, allow directional changes of the skeleton, energy storage (elastic modulus), proprioception (Golgi tendon organ), strength depends on the number, size, and orientation of collagen type I fibres

Normal Tendon Structure and Function - Additional Notes

• Toe region: Non-linear stretch, elimination of crimp; Linear deformation, area of curve where stiffness is determined; Yield region, irreversible lengthening of the tendon; Failure, rupture (approx. 4-10% strain)
• Protective mechanisms: Tendon sheaths (longer surface protection), Bursae (single point protection), Design to protect from shear damage, and Dictates tendon orientation

Normal Ligament Structure and Function

• Ligaments transmit forces between bone and bone: mainly tensile, structural integrity of joints
• Compared to tendon a ligament has: increased % type III collagen (lower volume collagen type 1), higher number of cells, increased PG at high compression sites
• Location: Incorporated into joint capsule (e.g., collaterals, suspensory ligament branches), Intra-synovial (e.g., Cr & Ca CXL, straight distal sesamoidean ligament)

Response of Tendons & Ligaments to Injury

• Tendons: Ultrasound enlargement, intra-tendinous oedema, hypoechoic foci, peritenon thickening, loss of myotendinous/osseous-tendon junctions, increased stiffness, reduced elasticity, reduced ROM
• Ligaments: Minimal oedema, loss of ligament definition, peri-ligamentous thickening, enthesopathy, increased stiffness, reduced/increased ROM

Pathophysiology of Tendon and Ligament Injuries

• A sliding scale from physiological modeling to failure
• Factors like degeneration, mechanical overuse, and trauma can contribute to injury

Ageing and Injury of Tendons

• Darker brown and reddish center at post-mortem due to degeneration
• Focal sites of chondroid metaplasia (high pressure sites)
• Pathological remodeling and progression to injury (tendons and ligaments)
• Predisposed sites (high-strain sites)
• Excessive stretching beyond elastic loading capacity leads to micro-damage and can cause failure
• Microdamage causes fibril breakdown, collagen disruption, loss of structural crosslinks between collagen fibres, chondroid metaplasia, and ischemia

Healing of Tendons and Ligaments

• Inflammation (24 hrs-14 days): Oedema, increased temperature, pain, loss of function
• Repair (2-28 days, peaking at 21 days): Proliferation of tenocytes, production of new ECM
• Remodelling (60+ days): Consolidation of repaired tissue and maturation, aim to minimize scar tissue formation
• Healing events: Intra-synovial and extra-synovial healing; Blood supply is key factor; acute vs. chronic lesions; dependent on duration of lesion
• Factors influencing healing: Severity of lesions, duration of lesion, poor blood supply leads to slower healing

Treatment of Tendons and Ligaments

• Goals: Resolve pain and inflammation, restore function, optimize function
• Treatment options: Many, but few used in isolation; best outcomes found with controlled and gradually increasing exercise, eccentric loading of affected structures, Gold standard (e.g., heel raises)
• Surgical Treatments: Aim to minimize adhesion formation, improve gliding function, remove contamination
• Arthroscopic/endoscopic debridement (equine), tenorrhaphy/tenodesis, open surgical repair (more typical in canine), tenorrhaphy, tenotomy.
• Material Selection for Tenorrhaphy/repair: Should be easy to pass through tissue, non-irritant, good knot security, adequate strength
• Treatment Options: Monofilament nylon, Polypropylene, Polydioxanone
• Ligament Surgical Repair (Mostly canine): Aim to restore joint stability, suture repair as for tendons, anchor through bone tunnel or suture anchor (if tissue destroyed), screw and washer for avulsions; prosthetics/implants
• Restore function = Requires Time: increasing use of biologics, mesenchymal stem cells, adipose-derived stem cells, platelet-rich plasma, autologous protein solution, exercise.
• Optimal Function: Rehabilitation, controlled exercise programs, walking, underwater treadmill, pole work, daily stretches, modalities (Laser, ECSWT, cryotherapy). Prevents adhesions
• Prevention of injury: Starting from low level exercise , gradual loading, warm-up and cool-down periods, regular stretching, hydration, rest days, appropriate nutrition, adequate support

Summary

• Thorough examination and diagnostics critical
• Tendons and ligaments need time, appropriate exercise, and often structural repair for optimal function
• Client education and cooperation are key for positive outcomes

References

• A plethora of references for tendon & ligament physiology, common diseases. Specific titles of books are provided