Phases of Healing

SALLY WHITE, MOTSTHE UNIVERSITY OF MISSISSIPPI

MEDICAL CENTER

Phases of Healing

Phases of Healing

There are 3 main phases of healing for soft tissue Inflammatory Phase

Typically begins within the first 6-8 hours Time frame: 2-5 days Macrophages become the dominate cell type to debride damaged tissue

Proliferation Phase Fibroblast cells mark the beginning of this phase

Lay down at collagen matrix Site appears red due to need for oxygen Collagen deposition occurs

Remodeling/Maturation Phase Collagen production and degradation equalize Strength approaches about 50% of tissue’s normal strength about 3

months post injury

All phases over-lap

Patient Factors Affecting Healing

Diabetes Mellitus Diabetic scars have less collagen Collagen that is laid down is more brittle than normal May not have good blood supply; especially to distal extremities

Malnutrition Slow healing due to breakdown of protein source for energy May have vitamin deficiency

Age Increase in age is an increase in healing time

Smoking Infection to Site/ Re-injuryLocal Skin TensionIschemia/Hypoxia

Tendons

Are cord-like structures that attach muscles to bones

Can be classified as gliding or vascular Gliding: Enclosed in the tendon sheath- the synovial

sheath Common example: Flexor tendons in the Hand

Vascular: Are surrounded by connective tissue Achilles Tendon

Tendons are stronger per unit area than muscle, and their tensile strength equals that of bone, although it is flexible and slightly extensible.

Collagen constitutes 75% of the dry tendon weight and functions chiefly to withstand and transmit large forces between muscle and bone.

Tendons

Common Tendon Injuries

Common Injuries: Tendonitis- Inflammation

Common areas: RTC (supraspinatus), lateral epicondylitis, patellar tendon

Tendinosis- Degenerative Chronic, accompanied by pain and associated with

thickening of the tendon itself

Paratenonitis- Inflammatory disorder of tissue surrounding the tendon (sheath) Common cause: Repetitive friction Also goes by: Peritendonitis, Tenosynovitis

Tendon Phases of Healing

Initial Inflammatory phase Begins within 24 hours of injury Neutrophils enter injury site Tenocytes migrate to wound gradually for type-III collagen synthesis initiation

Therapy during this phase: Controlled stretch to increase collagen synthesis and to improve fiber

alignment. Gentle passive range of motion can result in higher tensile strength.

Repetitive motion can increase DNA content and increase protein synthesis.

Proliferative Phase Last up to 6 weeks Tendon fibroblast synthesizing collagen and other matrix components Synthesis of type III collagen peaks- water content remains high

Tendon Phases of Healing Continued

Remodeling Phase Week 6- Up to 1 year post injury

Broken down into 2 stages Consolidation- Week 6-10

Type-I collagen Collagen fibers align in the direction of stress response

Maturation- Week 10+ Gradual change of fibrous tissue to scar-like tendon

tissue over the course of a year

Ligaments

Ligaments are the most frequently injured tissues within a joint.

When a ligament is overloaded, or exposed to tensions greater than the structure can sustain, the tissue fails, resulting in partial or complete ligament discontinuities, more commonly known as disruptions or tears.

Ligaments

Ligament injures create disruptions in the balance between joint mobility and stability, causing abnormal force transmission, which results in damage to other structures in and around the joint.

The long-term consequence of non-healed ligament injury is osteoarthritis, the most common joint disorder.

Ligaments heal through a distinct sequence of cellular events that take place in three consecutive stages.

Ligament Phases of Healing

Acute inflammatory phase Begins within minutes of injury and continues over the

next 48 to 72 hours. Blood collects at the site of injury and platelet cells

interact with certain matrix components, changing their shape and initiating clot formation.

When stimulated by growth factors, neutrophils, monocytes, and other immune cells migrate to the injured tissue where they ingest and remove debris and damaged cells: thereby initiating matrix turnover.

Ligament Phases of Healing

Proliferative phase Begins when immune cells release various growth factors

and cytokines: which initiates fibroblast proliferation signals for rebuilding of the ligament tissue matrix.

The tissue formed initially appears as disorganized scar tissue, consisting of more blood vessels, fat cells, fibroblasts, and inflammatory cells than normal ligament tissue contains.

Over the next several weeks, fibroblast cells deposit various types of collagen, proteoglycans, glycoproteins, and other proteins into the matrix.

The collagen becomes aligned with the long axis of the ligament during this time; however, the newly-formed collagen fibrils are abnormal and smaller in diameter than normal ligament tissue.

Ligament Phases of Healing

Remodeling phase Collagen maturation begins, often lasting for months

to as long as years after the initial injury. The tissue matrix starts to resemble normal ligament

tissue; however, critical differences in matrix structure and function persist. Evidence suggests that the injured ligament structure is

replaced with tissue that is grossly, histologically, biochemically, and biomechanically similar to scar tissue

Bone Healing

Bone heals with bone- which is unlike any other tissue which heals with scar tissue

Type of healing (primary or secondary) depends on method of treatment of the fracture

Primary Bone Healing/Direct or Primary Cortical

The cortex of the bone attempts to directly re-establish continuity

Rigid stabilization/Fixation

Some regions of the cortex are in direct contact with other cortical region at fracture site

There is no callus formation

Contact Healing Gap Healing

Healing takes place across contact area (<0.01mm)

Bone reconstruction begins with direct formation of lamellar bone

Initiated by formation of “cutting cones” close to fracture line

When small gaps (1mm) form between bone ends and interfragmentary deformation is very low

Healing involves the osteoblast cells to invade blood vessels- concentric bony rings around Haversian systems & osteoclasts to remodel

Primary Healing

Secondary Bone Healing

This is how the majority of bones healAlso called indirect bone healingRelies on the periosteum for the healing

processThe amount of callus formation depends on

the stability of the fracture

Phases of secondary bone healing

Impaction Phase Bone absorbs the energy; fractures along the line of least

resistance Impact damages the bone, bone marrow, periosteum,

adjacent soft tissue, and vessels within the bone

Inflammatory Phase Begins immediately after initial disruption and last 3-4

days Hematoma forms- which is critical to healing. It allows for

structural stability and is the framework for the new bone Thrombosis occurs Pain, swelling and heat at fracture site

Secondary Bone Healing

Repair Phase Last about 2 weeks Growth of new capillaries Slight gain in mechanical strength of fracture Soft callus formation

Callus Mineralization Stage Begins 1 week after soft callus formation. This stage can last 4-16 weeks Increased oxygen tension The amount of callus is dependent on stability of fracture fragments

The more motion at the fracture site will result in larger callus formation

Initiation of controlled AROM can begin between 3 and 6 weeks post-injury if the fixation of the fracture is adequate

Bone Healing

Remodeling Phase Can take several years to complete Bone continues to form and becomes more compact Dependent on adequate blood supply and stability

Wound Healing

Wounds/Burns

Inflammatory Last 3-5 Days Bacteria is phagocytosed and removed from site Begin the cleaning of the site

First Part of Inflammatory Phase: Vascular response Main task: stop hemorrhage

Second Part: Cellular Response Fibrin and other proteins act as glue for wound site

Therapy: Edema reduction, wound care and maintenance, early range of motion, positioning and splinting

Wounds/Burns

• Proliferative Angiogenesis, collagen deposition, formation of

granulation tissue, epithelialization, and wound contraction

Fibroblast arrive to further strengthen the wound

Therapy: Edema reduction, Wound care and maintenance, early range of motion, positioning and splinting, stretching and strengthening

Wounds/Burns

Remodeling Collagen is remodeled and realigned along the tension

lines Scar maturation takes 6-18 months This stage is fragile and can take up to 2 years for a

severe burn patient

Therapy: Range of motion, strengthening and reconditioning, scar management techniques

References

Hauser, R.A., Dolan, E.E., Phillips, A.C., Moore, R.E., & Woldin, B.A. Ligament Injury and healing: a review of current clinical diagnostics and therapeutics. The Open Rehabilitation Journal, 2013, 6, 1-20.

McCulooch, J.M. & Kloth, L.C. (year), Rehabilitation of the burned individual. In Wound Healing- Evidence Based Management (4 ed, pp. 357-390)

Pendleton, H.M. & Schultz-Krohn, W. Pedretti’s Occupational Therapy Practice Skills for Physical Dysfunction (6th edition, 994-995, 1005-1007, 1022-1024)

Sharma, P. & Maffulli, N. Tendon injury and teniopathy: healing and repair. J Bone Joint Surg. Am. 87:187-202, 2005. doi: 10.2106/JBJ5.D.01850.