Chapter 4: Healing Trajectories


  • Douglas Queen BSc, PhD, MBA



Accurate and clinically practical methods for measuring the rate of wound healing are necessary before calculating healing rates and distinguishing wound progression, stalled wounds and a worsening wound status.

If a wound is not at least 20% to 40% smaller by week 4, it is unlikely to heal by week 12 (Sibbald et al, 2021). Stalled (healable) wounds should be reevaluated for alternate diagnoses; consider wound biopsy, further investigation, and/or referral to an interprofessional assessment team to optimize treatment. Healing trajectory can be assessed in the first 4 to 8 weeks to predict if a wound is likely to heal by week 12, provided there are no new complicating factors (Laporte et al, 2015). Changes in the wound, the individual or their environment, may necessitate the reclassification of a wound to the maintenance or nonhealable category.

Wound healing trajectories are a useful tool for evaluation of time to healing, especially with the utilization of clinical data. Wound healing trajectories are an important evaluation tool for acute wounds and chronic wounds including venous stasis ulcers, diabetic foot ulcers, pressure injuries and others.

Learning Objectives

  1. Describe chronic would healing trajectories
  2. Compare the concepts of chronic wound healing trajectories, wound healability classifications and treatment interventions
  3. Identify the benefits of early healing time predictions


Chronic wounds heal slowly and this contributes to the significant management cost (Han and Ceilley, 2017). Classification of wound healability is one of the first steps providers must take after an accurate diagnosis is established. In some cases, interprofessional input may be required to determine an accurate diagnosis, complicating factors and wound healing classification. These are holistic and fundamental first steps in the Wound Bed Preparation paradigm.

Generally, chronic wounds are classified into one of three categories: healable, maintenance, and nonhealable. Providers readily accept that the wound healability classification may change. Wound healing is impacted by many factors and can be complex. Changing health status, lifestyle choices and available resources also influence approaches to chronic wounds and healing outcomes.

As a patient with a chronic wound enters the health care system or moves between sectors, baseline wound assessments are performed. Wound measurements must be standardized (longest length × widest width at 90° or head-to-toe & side-to-side) as part of this initial assessment process. Subsequent wound assessments must utilize the same methodology so that comparisons can determine the healing trajectory.

Evaluate Chronic Wound Healing

If a wound is not at least 20% to 40% smaller by week 4, it is unlikely to heal by week 12. Providers are required to calculate and communicate the rate of healing (healing trajectory) as outlined in Table 1. Note the healing trajectory over time can be either positive (smaller) or negative (larger).

Table 1. Evaluating the Rate of Healing of a Chronic Wound:  

How to Calculate Wound Surface Area from Two Assessments 4 weeks apart

 Longest length (cm)    ✕    widest width (cm)                        = surface area (cm2)

(In any direction)           (perpendicular to the length)

Example: First visit, surface area is 4cm ✕ 2cm = 8cm2

Second visit, surface area is 4cm ✕ 1cm = 4cm2

How to Calculate Percentage of Wound Healing (Wound Healing Trajectory)

 First visit area (cm2) MINUS Second visit area (cm2) = difference in surface area

Example from above: 8cm2 – 4cm2 = 4cm2

Difference in Surface Area / First visit Surface area X 100 = reduction of wound surface area  between visits

=4cm2 / 8cm2 ✕ 100 = 50% wound surface area reduction between visits

This wound is in a positive wound healing trajectory as it is getting smaller.

Reference: Sibbald, et al, Wound Bed Preparation, 2021

Stalled (healable) wounds should be re-evaluated, often requiring further investigations (e.g., wound biopsy, other tests) for possible alternate diagnosis along with treatment change. Referral to an interprofessional assessment team to optimize management may be necessary, that will often result in improved wound outcomes.

Healing trajectory can be assessed in the first 4 to 8 weeks to predict if a wound is likely to heal by week 12, provided there are no new complicating factors.

For the stalled non-healable and maintenance wounds, re-evaluating by means of assessments and measurements still play a role in ongoing monitoring. When the goal is to prevent further deterioration, maintaining a neutral healing trajectory may be confirmed. A negative healing trajectory may occur in the non-healable wound where efforts shift to patient centered concerns including pain management, exudate, smell and comfort strategies.

Providers can use the healing trajectory (positive, neutral or negative percentage of wound closure over time) to inform the treatment and intervention plans.

Local wound care strategies (Sibbald et al, 2021) will vary by the wound healing classification as illustrated below.

  • Healable Wounds: have the potential to heal (Sibbald et al, 2012)
    These wounds have sufficient vascular supply, the underlying cause can be corrected & general health can be optimized (Sibbald et al, 2012).
    The goal is for closure of the wound in a timely fashion with ongoing functional integrity including prevention of recurrences.
  • Maintenance Wounds: have healing potential, but various patient factors are compromising current wound healing (Orsted et al, 2010).
    The goal is not necessarily to heal the wound, but to reduce the risk of infection and further deterioration while promoting client self-management and independence of the wound care regime.
  • Nonhealable Wounds:  Lack the ability to heal due to untreatable causes such as terminal disease, end-of-life or other organ failures (Despatis, 2008).
    The goal is to promote comfort and reduce the risk of infection and possibly prevent further deterioration.

Both maintenance and non-healable wounds are the most challenging from both the clinician’s and patient’s perspective, in addition to being resource intensive to the healthcare system. A systematic review explored the evidence for nonhealable and maintenance wound management and proposed an interprofessional referral pathway for these wounds based on the findings (Boersema G.C. et al., 2021).

Table 2. Local wound care strategies are customized for each wound healing classification

Wound Healing Classification Considerations Sharp Surgical Debridement
(All with adequate pain management strategies implemented)
Inflammation/Infection Management
(when 3 or more NERDS or STONEES criteria confirmed)
Moisture Management
Healable Provide moist environment Active (within the scope of provider) Treat inflammation/infection (topically or systemic) Moisture balance
Promote granulation
Maintenance Decrease moisture and bacteria Conservative (no bleeding) Bacterial reduction
Topical antisepsis/ systemic antimicrobial
Moisture reduction
Prevent deterioration
Nonhealable Decrease moisture and bacteria Contraindicated in some cases
Gentle removal of non-viable necrotic tissue if needed
Bacterial reduction
Topical antisepsis/ systemic antimicrobial
Moisture reduction
Prevent infection
Enhance comfort

Adapted from Sibbald et al, 2015 and Sibbald et al, 2021.