on patient-specific variables, develop a treatment plan with a reasonable chance of success (▶Video 7.1).
Keywords: nonunion, malunion, hypertrophic, atrophic, bone graft
I. Assessment of Nonunions
Factors leading to nonunion can generally be grouped into two categories: biologic and mechanical. The assessment is a gathering of data on known factors which may have contributed to a failure of the biologic and mechanical success of the fracture healing.
A. History
1. Common presenting symptoms:
a. Pain at the fracture site (increased with weightbearing).
b. Subjective feelings of instability in the affected bone.
c. Symptoms (or history of symptoms) associated with infection: erythema, swelling, drainage, fevers, chills.
2. The data of patient-specific risk factors is obtained after completing a thorough history with each individual patient.
a. Demographic/patient directed risk factors:
i. Smoking has negative effects on many pathways necessary for bone healing.
ii. Nicotine diminishes arterial blood flow.
iii. Nonsteroidal anti-inflammatory drugs negatively affect the pathways responsible for bone healing.
iv. In some studies, female patients and older patients had an increased rate of nonunion.
v. Poor nutrition is associated with nonunion.
b. Associated comorbidities:
i. Metabolic and endocrine dysfunction can impair fracture healing.
ii. Diseases that negatively affect vascularity, such as diabetes mellitus and other vascular disorders, can impair fracture healing.
3. Fracture-dependent risk factors are independent of the patient; each practitioner must have an adequate baseline knowledge of previous reported literature on fracture healing.
a. Certain bone-specific anatomy is associated with nonunion, often due to poor vascularity in these areas. Examples include:
i. Open tibia fractures.
ii. Intracapsular hip fractures.
iii. Talar neck fractures.
iv. Proximal metadiaphyseal fifth metatarsal fractures.
b. Open fractures and bone loss are associated with increased nonunion rates. The higher the open fracture type, the greater is the risk of nonunion (and infection).
4. Risk factors from previous care:
These can be investigated using previous operative reports and medical documentation from the original perioperative period.
a. Soft tissue destruction impairs the vascularity at the fracture site.
i. Traumatic or surgical disruption—this can be due to vascular damage or due to excessive soft tissue stripping either from the injury or from a surgical procedure which was not biologically friendly.
b. Interposed soft tissue at the fracture site if the fracture was not opened and debrided.
c. History of infection at the fracture site:
i. Previously undiagnosed infection.
ii. Important to determine if the patient had cellulitis, wound drainage, or other concerning symptoms after the original treatment.
d. Improper fixation—too much or too little strain at the fracture site (refer to Chapter 4, Biomechanics of Internal Fracture Fixation, for additional details).
i. Doctor needs to critically assess the method of fixation and correlate it to the desired mode of healing at the fracture site.
ii. Too rigid fixation in a zone of comminution will lead to a lack of callus formation.
iii. Too flexible or inadequate fixation may cause excess soft callus to form without eventual maturation to rigid callus.
e. Improper fixation—residual fracture gap, especially if > 1 cm.
B. Physical exam
1. Inspection:
a. Deformity at the fracture site—look for alterations in length, alignment, and rotation. Note if deformity occurs with passive motion or only with active motion or weight bearing.
b. Current soft tissue envelope is very important in developing a treatment plan.
i. Ulceration.
ii. Open wounds.
iii. Exposed hardware.
iv. Damaged tissue.
c. Evidence of decreased vascularity to the region:
i. Previous scars.
ii. Thin or damaged skin.
iii. Atrophic or damaged muscle.
d. Evidence of vascular disease:
i. Varicosities.
ii. Cool limbs.
iii. Poor hair/nail growth.
iv. Chronic erythema of skin.
2. Palpation:
a. Tenderness at the fracture site.
b. Pathologic motion at the fracture site (should not have any detectable motion).
c. Palpable distal pulses indicate reliable overall vascularity.
d. Decreased sensation distal to the fracture site is a marker for neuropathy or nerve injury.
e. Evaluate motion at the joints above and below the nonunion site and test them both actively and passively.
3. Gait evaluation:
a. Observe for signs of muscle weakness:
i. Antalgic gait.
ii. Trendelenburg gait.
C. Imaging
1. Radiographs:
These are the mainstay of the assessment; it is important to obtain historical imaging if the patient has been treated at other facilities. Obtain full-length anteroposterior and lateral X-rays of the involved bone. Additional oblique or specialty views may be necessary depending on the location.
a. Expected results:
It is important to understand what to expect on an X-ray based on the previous method of fixation (refer to Chapter 1, Physiology of Fracture Healing, for additional information).
i. Primary bone healing—no callus.
ii. Secondary bone healing—callus formation.
b. General signs of nonunion:
i. Absence of bone bridging at the fracture site/persistent fracture line. Particularly the lack of progression on serial radiographs.
ii. Sclerotic edges at the fracture site.
iii. Implant loosening or breakage can be indicative of pathologic motion from a nonunion.
iv. Change in fracture alignment.
v. Typically painful for the patient.
c. General classification of nonunions:
It is important to have a good working knowledge of bone healing and the biomechanics of fracture repair.
i. Primarily mechanical issues.
ii. Primarily biologic issues.