1. Tendon, Ligament, and Muscle Injuries
Robert A. Magnussen, MD
Assistant Professor, Department of Orthopaedic Surgery
Team Physician, OSU Sports Medicine
The Ohio State University Wexner Medical Center

2. Learning Objectives Tendon
Differentiate between tendinosis, tendinitis, and tenosynovitis
Define tendon rupture
Differentiate between acute and chronic tendon ruptures and the impact of this on treatment
Understand the concept and phases of tendon healing
Ligament
Describe the mechanisms of ligament injuries
Understand the grading of ligament sprains (Grades 1-3)
Contrast the healing of intra- versus extra-articular ligaments
List the key phases of ligament healing
Muscle
Describe te main forms of muscle injury
Describe muscle degeneration and regeneration

3. Tendon Injury
Tendon Injury

4. Background - Tendons Function Attach muscles to bones.
Transmit tensile loads allowing muscles to move the skeleton.
Composition
Mostly type I collagen (86% of dry weight)
Produced by fibroblasts.
Function
Attach muscles to bones.
Transmit tensile loads allowing muscles to move the skeleton.
Composition
Mostly type I collagen (86% of dry weight)
Produced by fibroblasts. 4

5. Meyers et al, Prog Mat Sci, 2008
Collagen Is organized into fibrils in a matrix of proteogylcans.
Fibrils arranged in parallel rows into fascicles which in turn make up tendons
Mircoscopic evaluation of fascicles reveals a crimp pattern in the collagen fibers related to the absence of proline and hyroxyprolineresidues at specific intervals. These crimps incerase the flexibility of tendons in the early portion of loading
Meyers et al, Prog Mat Sci, 2008 5

6. Tendon Disorders Tendinopathy: general term for disease of tendons.
Includes:
Tendinitis: tendon inflammation
Tendinosis: tendon degeneration
Tenosynovitis:
Inflammation of the synovial sheath surrounding a tendon
Tendinosis involves alteration to cells, collagen fibers, and matrix components 6

7. Tendinitis Refers to inflammation of tendon.
Is generally due to partial tendon tears and the associated healing response.
Histology reveals inflammatory cells, fibroblasts, evolving hematoma and granulation tissue. Evidence of prior degenerative change is also frequently seen.
Refers to inflammation of tendon.
Is generally due to partial tendon tears and the associated healing response.
Histology reveals inflammatory cells, fibroblasts, evolving hematoma and granulation tissue. Evidence of prior degenerative change is also frequently seen.

8. Tendinosis
Refers to degenerative change within the substance of tendons.
Much more common than tendinitis.
Increasingly common with increased age.
Numerous conditions are often referred to as various types of tendinitis that actually represent tendinosis.
Achilles tendinitis, patellar tendinitis, rotator cuff tendinitis, lateral epicondylitis, etc…
Refers to degenerative change within the substance of tendons.
Much more common than tendinitis.
Increasingly common with increased age.
Numerous conditions are often referred to as various types of tendinitis that acutally represent tendinosis.
Achilles tendinitis, patellar tendinitis, rotator cuff tendinitis, lateral epicondylitis, etc…

9. Tendinosis Histology reveals evidence of degenerative change:
Collagen fiber disorganization
Increased mucoid appearance
Increased vascularity (neovascularization)
Focal areas of necrosis
Inflammatory cells are generally not present
Histology reveals evidence of degenerative change:
Collagen fiber disorganization
Increased mucoid appearance
Increased vascularity (neovascularization)
Focal areas of necrosis
Inflammatory cells are generally not present

10. Tenosynovitis
Refers to inflammation of the synovial lining of a tendon.
Can be aseptic or related to infection.
Histology reveals numerous inflammatory cells invading the synovial lining of the tendon. The tendon itself is minimally involved in the process.
Refers to inflammation of the synovial lining of a tendon.
Can be aseptic or related to infection.
Histology reveals numerous inflammatory cells invading the synovial lining of the tendon. The tendon itself is minimally involved in the process.

11. Summary of Tendinopathy
Pathological Diagnosis
Concept
(macroscopic pathology)
Histological Findings
Tendinosis
Intratendinous degeneration (commonly due to ageing, microtrauma, vascular compromise)
Collagen disorientation, disorganisation and fibre, separtion by an increase in mucoid ground substance, increased prominence of cells and vascular spaces with or without neovascularization and focal necrosis or calcification.
Tendinitis/ Partial rupture
Symptomatic degeneration of the tendon with vascular disruption and inflammatory repair response.
Inflammatory response, including fibroblastic and myofibroblastic proliferation, haemorrhage and organising granulation tissue.
Summary of Tendinopathy Graph
Khan et al, Sports Med 1999

12. Tendon Rupture
Often results from eccentric loading beyond the capacity of the tendon.
Tendons are able to stretch less than ligaments without suffering injury due to their collagen alignment – less crimping.
Injury occurs on a continuum as load increases:
Strain / Partial rupture
Complete rupture
Often results from eccentric loading beyond the capacity of the tendon.
Tendons are able to stretch less than ligaments without suffering injury due to their collagen alignment – less crimping.
Injury occurs on a continuum as load increases:
Strain / Partial rupture
Complete rupture 12

13. Tensile Properties
Toe region is straightening / alignment of crimped fibrils parallel with force.
Stiffness:
Slope in linear region
Ultimate load
Energy absorbed
Area under the curve

14. Tendon Rupture
Complete ruptures can occur in normal tendons if a sufficiently large load is applied.
More commonly, complete tears occur in the setting of pre-existing degenerative change that has weakened the tendon and predisposed it to rupture with a smaller load.
Complete ruptures can occur in normal tendons if a sufficiently large load is applied.
More commonly, complete tears occur in the setting of pre-existing degenerative change that has weakened the tendon and predisposed it to rupture with a smaller load.

15. Implications for Treatment
Acute Traumatic Tears:
Acute traumatic tendon ruptures are generally treated with operative repair.
End-to-end repair or direct re-insertion of avulsions to their native bony attachments is frequently possible.
Acute Tramatic Tears:
Acute traumatic tendon ruptures are generally treated with operative repair.
End-to-end repair or direct re-insertion of avulsions to their native bony attachments is frequently possible.

16. Implications for Treatment
Chronic Attritional Tears:
Chronic degenerative change (tendinopathy) can lead to gradual loss of tendon integrity without an acute traumatic event.
Most commonly seen in the rotator cuff tendons.
Such tears are often asymptomatic if other muscles have adapted to perform the function of the degenerated tendon (eg arm abduction).
Chronic Attritional Tears:
Chronic degenerative change (tendinopathy) can lead to gradual loss of tendon integrity without an acute traumatic event.
Most commonly seen in the rotator cuff tendons.
Such tears are often asymptomatic if other muscles have adapted to perform the function of the degenerated tendon (eg arm abduction).

17. Implications for Treatment
Chronic Attritional Tears
Asymptomatic tears of this type often do not require treatment.
If symptoms develop:
Nonoperative treatment is the first line, focus on restoring function though compensation using intact muscle groups.
Such as the deltoid functioning to list the arm following attritional tear of the supraspinatus muscle.
If nonoperative treatment fails, surgical repair may be performed but is often compromised by lack of normal quality tissue for repair.
Chronic Attritional Tears
Asymptomatic tears of this type often do not require treatment.
If symptoms develop:
Nonoperative treatment is the first line, focus on restoring function though compensation using intact muscle groups.
Such as the deltoid functioning to list the arm following attritional tear of the supraspinatus muscle.
If nonoperative treatment fails, surgical repair may be performed but is often compromised by lack of normal quality tissue for repair.

18. Inflammatory Fibroblastic Remodeling Tendon Healing 3-5 Days
Fibrin clot produced
Fibroblastic
1-6 Weeks
Production of collagen and matrix to form a disorganized tendon “callus”.
Inflammatory
3-5 Days
Fibrin clot produced
Fibroblastic
1-6 Weeks
Production of collagen and matrix to form a disorganized tendon “callus”.
Remodeling
6 Weeks – 9 Months
Reorganization of collagen into cross-linked organized pattern.
Remodeling
6 Weeks – 9 Months
Reorganization of collagen into cross-linked organized pattern. 18

19. Tendon Healing 3 days 1 week 2 weeks 3 weeks Image 1
3 days: clot with some fibroblasts
Image 2
1 week: Undif. Fibroblasts, capillary buds. Collagen synthesis has begun
Image 3
2 weeks: Fibrous bridge forming. Collagen perpendicular to tendon axis
Image 4
3 weeks: collagen fibers align parallel

20. Tendon Healing IMAGE Remodeling continues for months:
Increased ultimate tensile load
Decreased scar mass
This effect is diminished in the absence of loading.

21. Rehabilitation following injury
Rehabilitation of a healing tendon is driven by the stages of healing
Joints are immobilized in the inflammatory period and early remodeling to allow for production of new collagen and prevent injury of the repair tissue
As remodeling proceeds, load is progressively increased via increased range of motion and eventually strengthening activities to maximize return of function
Rehabilitation of a healing tendon is driven by the stages of healing
Joints are immobilized in the inflammatory period and early remodeling to allow for production of new collagen and prevent injury of the repair tissue
As remodeling proceeds, load is progressively increased via increased range of motion and eventually strengthening activities to maximize return of function

22. Ligament Injury
Ligament Injury

23. Ligament Function
Ligaments connect bones and provide stability to joint.
Especially at the extremes of motion.
Ligament dysfunction allows abnormal motion between bones where they articulate.
Ligaments connect bones and provide stability to joint.
Especially at the extremes of motion.
Ligament dysfunction allows abnormal motion between bones where they articulate.

24. Ligament Injury
Similar to tendons, ligaments fail when they are exposed to tensile loads that are beyond their capacity to resist.
Such loads are often placed when joints bend in unnatural directions.
Joint dislocation is frequently associated with ligamentous injury.
Similar to tendons, ligaments fail when they are exposed to tensile loads that are beyond their capacity to resist.
Such loads are often placed when joints bend in unnatural directions.
Joint dislocation is frequently associated with ligamentous injury.

25. Ligament Injuries Ligament injuries are called sprains.
Note the distinction from muscle/tendon injuries which are often termed strains.
Ligament injuries are called sprains.
Note the distinction from muscle/tendon injuries which are often termed strains.

26. Ligament Injuries Grade 1
Ligament is damaged by not appreciably stretched.
No increased joint laxity is noted on physical examination.
Ligament may be tender to palpation and painful if loaded.
Grade 2
Ligament is damaged and stretched but remains in continuity.
Increased joint laxity is noted on physical examination but an endpoint is noted.
Ligament is tender to palpation and painful if loaded.
Sprains to all ligaments can be graded on a scale from 1 to 3 depending on the severity of the injury.
Grade 1
Ligament is damaged by not appreciably stretched.
No increased joint laxity is noted on physical examination.
Ligament may be tender to palpation and painful if loaded.
Grade 2
Ligament is damaged and stretched but remains in continuity.
Increased joint laxity is noted on physical examination but an endpoint is noted.
Ligament is tender to palpation and painful if loaded.
Grade 3
Ligament is completely ruptured.
Increased joint laxity is noted on physical examination without an endpoint.
May be associated with a dislocation of the joint.
Grade 3
Ligament is completely ruptured.
Increased joint laxity is noted on physical examination without an endpoint.
May be associated with a dislocation of the joint.

27. Extra-articular Ligaments
Ligaments located outside of joint capsules have high healing capacity.
Commonly injured extra-articular ligaments:
Collateral ligaments of the knee
Collateral ligaments of the elbow
Ankle ligaments
Ligaments located outside of joint capsules have high healing capacity.
Commonly injured extra-articular ligaments:
Collateral ligaments of the knee
Collateral ligaments of the elbow
Ankle ligaments

28. Acute Medial Collateral Ligament (MCL) Injury of the Knee
IMAGE
A T2-weighted image of an acute knee injury demonstrates edema and a complete (Grade 3) tear of the MCL.

29. Intra-articular Ligament
Ligaments inside the joint have significantly reduced healing capacity due to the fibrolytic and anti-coagulative environment inside the joint.
Commonly injured intra-articular ligaments:
Cruciate Ligaments of the knee (ACL and PCL)
Scapholunate ligament in the wrist .
These ligaments generally will not heal without surgery to repair or reconstruct.
Ligaments inside the joint have significantly reduced healing capacity due to the fibrolytic and anti-coagulative environment inside the joint.
Commonly injured intra-articular ligaments:
Cruciate Ligamens of the knee (ACL and PCL)
Scapholunate ligament in the wrist .
These ligaments generally will not heal without surgery to repair or reconstruct.

30. Acute Anterior Cruciate Ligament ACL
Injury of the Knee
IMAGE
A T2-weighted image of an acute knee injury demonstrates a complete tear of the ACL.

31. Ligament Healing
Extra-articular ligaments heal through four predictable phases:
Inflammatory response
Cell proliferation
Remodeling
Scar maturation
Healed ligaments are generally more bulky and not as strong as native tissue.
Extra-articular ligaments heal through four predictable phases:
Inflammatory response
Cell proliferation
Remodeling
Scar maturation
Healed ligaments are generally more bulky and not as strong as native tissue.
West and Fu, OKU 8, Ch 2, 2005

32. Muscle Injury
Muscle Injury

33. Muscle Injury Mechanisms
Muscle can be injury through two primary means:
Indirect Injury
An outside force overpowers the muscles ability to respond normally.
Includes both acute strains and delayed onset muscle soreness .
Direct Injury
Direct laceration or contusion to the muscle.
Muscle can be injury through two primary means:
Indirect Injury
An outside force overpowers the muscles ability to respond normally.
Includes both acute strains and delayed onset muscle soreness .
Direct Injury
Direct laceration or contusion to the muscle.

34. Indirect Muscle Injury
Generally occurs when the muscle is being loaded eccentrically.
Injuries are on a continuum from microscopic damage to partial tears to complete ruptures.
Fatigued muscles that cross two joints are especially prone to injury:
Hamstrings, rectus femoris, gastrocnemius
Generally occurs when the muscle is being loaded eccentrically.
Injuries are on a continuum from microscopic damage to partial tears to complete ruptures.
Fatigued muscles that cross two joints are especially prone to injury:
Hamstrings, rectus femoris, gastrocnemius

35. Delayed Muscle Soreness
Occurs hours following intense exercise.
Lasts 1 to 5 Days
Nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to reduce symptoms.
Occurs hours following intense exercise.
Lasts 1 to 5 Days
Nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to reduce symptoms.

36. Muscle Repair
Skeletal muscle is relatively stable tissue with relatively low turnover in the normal physiologic state.
Less than 1-2% of cells turn over weekly in the adult.
However, skeletal muscle does have the ability to repair itself following significant injury.
Skeletal muscle is relatively stable tissue with relatively low turnover in the normal physiologic state.
Less than 1-2% of cells turn over weekly in the adult.
However, skeletal muscle does have the ability to repair itself following significant injury.

37. Muscle Repair
Following significant injury, muscle repair proceeds through stages:
Degenerative Stage
Regenerative Stage
Following significant injury, muscle repair proceeds through stages:
Degenerative Stage
Regenerative Stage

38. Muscle Degeneration Normal skeletal muscle tissue Muscle degeneration
Begins with the necrosis of muscle fibers.
Fiber necrosis triggers the invasion of inflammatory cells – neutrophils followed by macrophages .
IMAGE
Normal skeletal muscle tissue in cross section. A myofiber is noted with the arrow and the vascular bundle with the arrowhead.
Histology of muscle degeneration features necrotic myofibers (arrows) with large numbers of inflammatory cells (3 days post-injury).
Charge and Rudnicki, Physiol Rev, 2004

39. Muscle Regeneration Muscle degeneration Muscle Regeneration
Following the degenerative phase, myogenic cells move into the area, enlarge, and fuse, forming new muscle fibers.
IMAGE
Histology of muscle degeneration features necrotic myofibers (arrows) with large numbers of inflammatory cells (3 days post-injury).
Regeneration features the regenerating, growth and fusion of new myogenic cells. Regenerating fibers are smaller in caliber and feature central nuclei (arrows). (10 days post-injury.
Charge and Rudnicki, Physiol Rev, 2004

40. Myositis Ossificans
Is a pathologic condition in which calcification occurs within muscle tissue, leading to bone formation outside of normal bone tissue (heterotopic ossification).
It is generally associated with trauma to the muscle.
Is a pathologic condition in which calcification occurs within muscle tissue, leading to bone formation outside of normal bone tissue (heterotopic ossification).
It is generally associated with trauma to the muscle.

41. Myositis Ossificans Damron et al, JBJS-Am, 2003 IMAGE
Axial CT image of a patient with myositis ossificans of the quadriceps muscle (arrow).
Damron et al, JBJS-Am, 2003

42. Tendon Ligament and Muscle Injuries Quiz

43. Please direct questions to: robert.magnussen@osumc.edu

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