General Principles in the Assessment and Treatment of Nonunions

Matthew J. Weresh, MD

Original Author: Peter Cole, MD; March 2004

New Author: Matthew J. Weresh, MD; Revised August 2006

Definitions

• Nonunion: A fracture that has not and is not going to heal

• Delayed union: A fracture that requires more time than is usual and ordinary to heal

Previous Definitions of Nonunion

• Nonunion: A fracture that is a minimum of 9 months post occurrence and is not healed and has not shown radiographic progression for 3 months

Orthopaedic Advisory Panel: Food & Drug Administration, 1986

• Waiting 9 months or more is often inappropriate:– Prolonged morbidity– Inability to return to work– Narcotic dependence– Emotional impairment

• Definition of nonunion should not limit or prevent appropriate and timely intervention

– “The best treatment for nonunions is prevention”

Sir John Charnley

“The designation of a delayed union or nonunion is currently made when the surgeon believes the fracture has little or no potential to heal.”

Donald Wiss M.D. & William Stetson M.D.

Journal American and Orthopedic Surgery 1996

Classification of Nonunions

• Two important factors for consideration

• (1) Presence or absence of infection

• (2) Vascularity of fracture site

Classification

• (1) Hypertrophic

• (2) Oligotrophic

• (3) Avascular

Weber and Cech, 1976

Hypertrophic

• Vascularized

• Callus formation present on x-ray

• Elephant foot - abundant callus• Horse hoof - less abundant callus (see diagram)

Oligotrophic

• No callus on x-ray

• Vascularity is present on bone scan

Avascular

• Atrophic or similar to oligotrophic on x-ray

• Ischemic or cold on bone scan

Hypertrophic (elephant foot)

Hypertrophic (horse hoof)

Oligotrophic or atrophic

Incidence of Nonunion

Boyd et.al Connolly

No. 842(1965) No.602 (1981)

Tibia 35 % 62%

Femur 19% 23%

Humerus 17.5% 7%

Forearm 15.5% 7%

Clavicle 2% 1%

*Increasing frequency of tibial nonunion over time

Increasing relative incidence of tibial and femoral nonunion most likely secondary to improved limb salvage techniques

Etiology of Nonunion: Systemic

• Malnutrition

• Diabetes (neurovascular)

• Smoking

Malnutrition• Adequate protein and energy is required for

wound healing

• Screening test: – serum albumin– total lymphocyte count

• Albumin less than 3.5 and lymphocytes less than 1,500 cells/ml is significant

Seltzer et.al. JPEN 1981

Diabetes(Neuropathic Fractures)

• Neuro arthropathy is not entirely the result of unprotected weight bearing on an insensate joint

• Inability to control response to trauma can result in hyperemia, osteopenia, and osteoclastic bone resorption

Neuropathic Fracture Nonunions

• Treatment, conservative (bracing) and operative, are fought with complications

• No currently accepted algorithm

• Consider use of biphosphonates to decrease osteolytic response

Shelby et.al. Diab. Med. 1994

Connolly J.F. and Csencsitz T.A. CORR #348 1998

Young e.t. al. Diab. Care 1995

McCormack R.G. e.t. al. JBJS 1998

Smoking

• Decreases peripheral oxygen tension

• Dampens peripheral blood flow

• Well documented difficulties in wound healing in patients who smoke

Schmite, M.A. e.t. al. Corr 1999

Jensen J.A. e.t. al. Arch Surg 1991

Smoking vs. Fracture Healing

• Most information is anecdotal

• No prospective randomize studies on humans

• Retrospective studies show time to union– 69% delay in radiographic union with smoker (2 of 44

nonunions in smokers vs. 0 of 59 nonunion in nonsmokers) increased incidence of nonunion with smokers

Schmitz, M.A. e.t.al. CORR 1999

Etiology of Nonunion(Local Factors)

• Infection

• Energy of fracture mechanism

• Mechanical factors of fracture configuration– Increased motion between fracture fragments– Inadequate fixation– Wolf’s Law - lack of physiologic stresses to bone

• Anatomic location

Infection

“Of all prognostic factors in tibia fracture care, that implying the worst prognosis was infection”

Nicoll E.A. CORR 1974

The inflammatory response to bacteria at the site of the fracture disrupts callus, increases gap between fragments, and increases motion between fragments.

Energy of Fracture Mechanism

• Initial fracture displacement

• Fracture pattern i.e: – comminution– bone loss– segmental patterns

• Soft tissue disruption (vascularity and oxygen delivery)

Initial Fracture Displacement

• Delayed union and nonunion were nearly three times as frequent in tibia fractures with moderate to severe displacement as compared to fractures with slight displacement.

Nicoll E.A., 705 cases, 1964

Fracture Pattern

• Fracture patterns in higher energy injuries (i.e.: comminution, bone loss, or segmental patterns) have a higher degree of soft tissue and bone ischemia

Soft Tissue Disruption

• 1. Introgenic

• 2. Traumatic

Traumatic Soft Tissue Disruption

• Incidence of nonunion is increased with open fractures

• More severe open fracture (i.e. Gustillo III B vs Grade I) have higher incidence of nonunion

Gustilo et.al.Jol 1984 Widenfalk

et.al.Injury 1979 Edwards et.al.

Ortho Trans 1979 Velazco et.al.

TBJS 1983

Introgenic

• Excessive soft tissue dissection and periosteal stripping at time of previous fixation

Tscherne Soft Tissue Classification

• Not all high energy fractures are open fractures. This classification emphasizes the importance of viability of the soft tissue envelope at the zone of injury.

Fractures with Soft Tissue Injuries

Springer Verlag 1984

Soft Tissue Classification• Grade 0: Soft tissue damage is absent or

negligible

• Grade I: Superficial abrasion or contusion caused by fragment pressure from within

• Grade II: Deep, contaminated abrasion associated with localized skin or muscle contusion from direct trauma

• Grade III: Skin extensively contused or crushed, muscle damage may be severe. Subcutaneous avulsion, possible artery injury, compartment syndrome

Revascularization of ischemic bone fragments in fractures is derived from the soft tissue. If the soft tissue (skin, muscle, adipose) is ischemic, it must first recover prior to revascularizing the bone.

E.A. Holden, JBJS 1972

Mechanical Factors

• Excessive motion at fracture secondary to poor fixation, failed fixation, or inadequate immobilization

• Lack of physiologic mechanical stimulation to fracture area (i.e. nonweight bearing, fracture fixed in distraction, adynamic environment with external fixation)

Anatomic Location of Fractures

• Some areas of skeleton are at risk for nonunion due to anatomic vascular considerations i.e.:– Proximal 5th metatarsal, femoral neck, carpal

scaphoid

Diagnosis of Nonunion- History

• Nature of original injury (high or low energy)

• Previous open wounds of injury site

• Pain present at fracture site

• Symptoms of infection i.e. – Antalgic gait or decrease use secondary to pain

• History of any drainage or wound healing difficulties

Examination• Alignment

• Deformity

• Soft tissue integrity

• Erythema, warm, drainage

• Vascularity of limb– Pulses, transcutaneous oximetry

• Stability at fracture site– Pain assessed during this portion of examination

X-rays

• AP, lateral, and oblique (45degree internal and 45 degree external)

• In majority of cases, this is all that is required to confirm nonunion

• Examination under fluoroscopy to check for motion can occasionally be helpful also

Tomography• Linear tomograms

– Helpful if metallic hardware present

• Helps to identify persistent fracture line in:– Hyptrophic nonunions in which x-rays are not

diagnostic and pain persists at fracture site

• Computed tomography and MRI are replacing linear tomography if no hardware present

Subclinical Undetected Infection

• The main diagnostic dilemma in evaluation of nonunions

Radionuclide Scanning

• Technetium - 99 diphosphonate– Detects repairable process in bone ( not specific)

• Gallium - 67 citrate– Accumulate at site of inflammation (not specific)

• Sequential technetium or gallium scintigraphy– Only 50-60% accuracy in subclinical ostoemyelitis

Esterhai et.al. J Ortho Res. 1985

Smith MA et.al. JBJS Br 1987

Indium III - Labeled Leukocyte Scan• Good with acute osteomyelitis, but less

effective in diagnosing chronic or subacute bone infections

• Sensitivity 83-86%, specificity 84-86%

• Technique is superior to technetium and gallium to identify infection

Nepola JV e.t. al. JBJS 1993

Merkel KD e.t. al. JBJS 1985

MRI• Abnormal marrow with increased signal on T2

and low signal on T1• Can identify and follow sinus tacts and

sequestrum• Mason study- diagnostic sensitivity of 100%,

specificity 63%, accuracy 93%

Berquist TH et.al. Magn Res Img

Modic MT et.al. Rad. Clin Nur Am 1986

Mason MD et.al. Rad. 1989

Tissue Biopsy• Antibiotic discontinued for 72 hours prior to

biopsy

• Multiple representative biopsy specimens should be obtained

• Cultures sent for gram stain, aerobic, anerobic, fungal, and acid fast studies

• Open biopsy techniques can be inconclusive due to problem of detecting bacteria protected by an external glycocalyx

Gristina AG el.al

Inst Con Lect 1990

Treatment

• Nonoperative

• Operative

Nonoperative

• Ultrasound

• Electric stimulator

• Bone marrow injection

Ultrasound• Ultrasound fracture stimulation devices

have shown ability to increase callus response in fresh fractures (shortens time for visible callus on x-ray)

• Prospective randomized trial in nonunion population has not been done

• Use in nonunions remains theoretical Goodship & Kenwright

JBJS 1985

Electric Stimulation

• Piezoelectric nature of bone - stress generated electric potentials exist in bone and are related to callus formation Fukada & Yasuda,J Phys Soc Jpn 1957 Busse H CAL e.t. al. Science 1962

• Electromagnetic fields influence vascularization of fibrocartilage, cell proliferation & matrix production

Monograph Series,AAOS

Three Modalities of Electric bone Growth Stimulators

• 1. Direct current - percutaneous or implanted electrodes

• 2. Electromagnetic stimulation - uses time varying magnetic fields (noninvasive)

• 3. Capacitive coupling - uses electrodes placed on skin (noninvasive)

Two Attempts at Well Controlled Double Blind (placebo) Studies on Nonunion

Healing with Electric Stimulation• 1. Pulsed electromagnetic fields

– Tibial delayed unions 16-32 weeks from injury– 45% united in active device group– 14% united in placebo group

(P < 0.02) Sharrard JBJS e.t. al 1990

• 2. Capacitive coupling– 6 of 10 with active device healed– 0 of 11 with placebo device healed

(P < 0.004) Scott

G and King JBJS 1994

Contraindication to Electric Stimulation

• Synovial pseudoarthrosis

• Electric stimulation does not address associated problems of angulation, malrotation and shortening

Unanswered Questions

• When is electric stimulation indicated

• Which fracture types are indicated

• What are the efficacy rates• What time after injury is best for

application

Ryaby JT Corr 1998

Bone Marrow Injection

• Percutaneous bone marrow injected to level of fracture

• 9 of 10 delayed tibia fractures united

• 80% of 100 tibial fracture patients united when in conjunction with adequate fixation

• *Nonradomized and anecdotal studies

Connolly J., CORR. 1995

Surgical Treatment

• Fibular osteotomy

• Bone graft

• Plate osteosynthesis

• Intramedullary nailing

• External fixation

Fibular Osteotomy

• Fibula can distract or unweight physiologic forces seen in the tibia Teitz, C.C. e.t.al.JBJS 1980

• Often used as adjunctive procedure to assist with deformity correction and surgical stabilization of tibia

• Dynamizes tibial to augment healing environment

Bone Grafting

• Osteoinductive - contain proteins or chemotactic factors that attract vascular ingrowth and healing – i.e.. demineralized bone matrix & BMP’s

• Osteoconductive - contains a scaffolding for which new bone growth can occur

– i.e. allograft bone, calcium hydroxyappatite

Bone Grafting

• Used to stimulate biologic response of healing in nonunions (usually atrophic nonunions)

• Also used to fill defects in fracture zone – i.e. up to 6 cm intercalary defects of long bones)

Bosse, MJ e.t.al. JBJS 1989

rhBMP-2

• 44% reduction in need for secondary intervention in the treatment of acute open tibial fractures

» Gorender,S e.t.al. JBJS 2002

rhBMP-2

• Reduces incidence of nonunion in high risk fractures

• Believed to reduce the need for autologous bone grafting

• Theoretically makes sense in the operative treatment of nonunions

Plate Osteosynthesis• Corrects malalignment

• Restores function & stabilizes fracture fragments directly

• Compresses fragments in some circumstances to augment healing

• Allows patients to mobilize surrounding joints and dynamize fracture environment

• Requires adequate skin and soft tissue coverage

• Often used with adjunctive bone graft

Locking Plate Technology

• Will give better fixation in pathologic bone

• Most likely will prevent early failure – Occasionally seen with traditional compression

plating techniques

Intramedullary Nailing

• Mechanically stabilizes long bone nonunions as a load sharing implant

• Corrects malalignment

• Reaming is initially detrimental to intramedullary blood supply, but it does recover and is believed to stimulate biologic healing at fracture

• Allow patient to mobilize surrounding joints and dynamize fracture environment

Intramedullary Nailing

• Can be performed without direct exposure or dissection of the fracture soft tissue envelope

• Nonapplicable in articular fractures

External Fixation• Correct malalignment• Used primarily in management of infected nonunions• Allows for repeated debridements, soft tissue

reconstructive procedures, and adjunctive bone-grafting• Small wire ring fixators can also allow for bone

transport into large intercalary defects• Ring fixators can also generate large compressive

forces at fracture to allow mobilization of joints and improve fracture healing environment

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