Unbelievable Bacteria- Part II

Why do open fractures have increased risk for infection?

The presence of bacteria within an open wound increases the risk of colonization when hardware is used. Once the hardware is colonized, the bacteria grows rapidly. During the rapid growth phase, the bacteria secretes a polysaccharide sugar layer, called a “biofilm”, or slime layer that encases the bacteria. This biofilm provides protection to the bacteria against the body’s defenses and antibiotics.

biooo

Within the biofilm, there are channels that allow the bacteria to pass nutrients, messaging signals, and even DNA to each other. The bacteria pass on their DNA by:

passDNA

  1. Transformation
  2. Transduction
  3. Conjugation

Transformation is when a bacterial cell ruptures, releasing its DNA, which is then taken in by another bacteria. Transduction occurs when DNA is transferred from one bacterium to another by a virus. Phage DNA and proteins are made and bacterial chromosomes are broken up, completing the gene transfer. The phage release themselves from the host, carrying either bacterial or phage DNA. Conjugation occurs when two bacteria attach themselves together with a sex pilus and exchange their DNA.

How does the bacteria become resistant to antibiotics?

beta

The bacteria can alter the genes they express by as much as 50-60%. By doing this, the bacteria can produce enzymes such as beta-lactamases, which destroy certain antibiotics before they can reach their target site. They can also make Efflux pumps which expel antibacterial agents from the cell before it can reach its target site. Finally, by expressing different genes, the bacterial cell wall can be altered to no longer contain the binding site of the antibiotic agent. Because the antibiotics cannot break through the biofilm and access the bacteria, the bacterium in the biofilm can become up to a thousand times more resistant to the antibiotics by the different mechanisms previously discussed.

If there is biofilm on the hardware, what can the physician do?

xfix

The only proven treatment, is to remove the hardware and wash the wound. However, removal of the hardware is a problem if the fracture is not healed and the fixation is needed. The physician may decide to suppress the infection, leaving the hardware until the fracture has improved. Or, the physician may decide the remove the hardware and seek an alternative method for stabilizing the fracture, such as an external fixator, and then using a biological material to help heal the fracture.

These are the issues that make infection with hardware so complex!

Advertisements

Low Back Pain- Disc Herniation

The spine is comprised of bony vertebrae separated by discs. The neural structures of the spine include the spinal cord (T12-L1), The conus medullaris—which is the lower end of the spinal cord, and the Cauda Equina, which is the division of multiple nerve roots beginning at the level of L1. Conditions of the lumbar spine including disc herniation are a main cause of lower back pain.

needs edits

The lumbar spine (lower back) consists of five vertebrae numbered L1-L5. These vertebrae are attached to the sacrum at the lower end of the spine. The discs between the vertebrae are round cushioning pads which act as shock absorbers. In a normal disc, there are two layers—the inner disc layer, which is comprised of soft gelatinous tissue and known as the Nucleus Pulposus, and the outer disc layer—which is made up of thick strong tissue, which is known as the Annulus Fibrosis. Behind this disc lies the spinal nerve root and the cauda equina. A major disc herniation of the lumbosacral region could affect the nerve roots.

parts

 

In about 95% of all disc herniation cases, the L4-L5 or L5-S1 disc levels are involved. Herniation of the L4-L5 disc will affect the L5 nerve root. Herniation of the L5-S1 disc will affect the S1 nerve root.

spinesections

There are three types of disc herniation:

  1. Protrusion/ Bulge- A bulging disc with intact annular and posterior longitudinal ligament fibers
  2. Disc Herniation
    • Type A—Disruption of inner annular fibers with intact outer annular fibers
    • Type B—Disrupted annulus with tail of disc material extending into the disc space
  3. Sequestration
    • Free fragment without tail extending into disc space
    • Fragment may be reabsorbed spontaneously
    • May get better with the use of an epidural

sequest

There are three typical locations for disc herniation as well:

  1. Central
    • Involves multiple nerve roots
    • Predominantly causes low back pain more than leg pain
    • May cause incontinence of the bladder and bowel
    • Urgent surgical treatment if patient presents with neurological deficits
  2. Posterolateral—usual location, most commonly involving one nerve root (the lower one)
    • For example: L4-L5 posterolateral herniation will involve L5 nerve root
  3. Foraminal
    • Occurs in 8-10% of cases
    • Involves the exiting nerve
    • Example: L4-L5 foraminal herniation will involve the L4 nerve root

Discogenic Back Pain is an internal disc disruption with early disc degeneration. Pain gets worse with flexion and sitting but, gets slightly better with extension. Forward flexion is limited on the exam and there are no radicular symptoms.

Child Abuse

Child abuse most often occurs under 3 years of age, and if it is not recognized and reported, repeat abuse may occur in 40% of the cases. Death can occur in up to 5% of cases.

Risk factors for Child Abuse include:

  • Being the first born child
  • Single Parent
  • Stepchild
  • Disabled Child
  • Parents were abused

It is important to rule out osteogenesis imperfecta and metabolic bone disease.

femurfx

Suspect Child abuse if:

  • There is a fractured femur in an infant before walking age
    • The most common orthopaedic injury associated with child abuse is a femur fracture
  • Multiple fractures in different stages of healing
    • Callus and periosteal reaction is seen
  • Unwitnessed spiral fracture
    • Spiral fractures are not a good criteria because most of them are accidental
  • Multiple soft tissue bruising
    • Skin lesions are the most common
    • Bone fracture is the second most common

skin lesions

  • Corner fracture
    • Metapheseal fracture especially in the distal femur and proximal tibia
    • Child abuse should be considered when health care providers see cornercornerfx fractures in children before they are of walking age.
  • Posterior rib fracture from a squeezing injury
  • If there is a transepiphyseal separation in the humerus
    • In Newborns
      • The olecranon moves posteriorly
      • Looks like an elbow dislocation
    • Older Child
      • Separation of the distal humerus usually occurs in younger ages

Discrepancy in the history is a clue. It is hard to explain the injury and match it with the given mechanism of the injury. Injuries in abuse mostly occur at the humerus, tibia, and femur (more in the diaphysis). When child abuse is suspected in a patient it is important to recognize the symptoms, be non-judgmental, and obtain a skeletal survey. If you suspect abuse and a skeletal survey is negative, obtain a bone scan to verify. Then consult protective services. The most frequent cause of long-term morbidity in an abused child is a head injury.

Salter-Harris Fracture Classifications

The Salter-Harris fracture is a common injury in children, involving the growth plates of the long bones. Approximately 15% to 30% of all childhood fractures are growth plate fractures and are common in the lower leg bones (tibia and fibula). It is important to detect these fractures as they may affect the growth of the bone if not treated properly.

There are five types of Salter-Harris fractures. The higher the type number, the more complications associated with the fracture.

typeIfx
Type I

Type I

Only 5% of fractures are Type I. It may be difficult to diagnose unless there is obvious displacement and sometimes the diagnosis is a clinical one. Type I fractures occur though the weak zone of the provisional calcification and are known for their fast healing and rare complication rate.

Type II:

typeIIfx
Type II

Approximately 75% of fractures are type II. These fractures occur at the physis (growth plate) and metaphysis – and when the corner of the metaphysis separates (Thurston-Holland Sign). The fragment usually stays with the epiphysis while the rest of the metaphysis will displace. Typically, healing is fast and growth is usually okay; however, distal femur fractures may result in growth deformity.

 

Type III:

10% of fractures are Type III, which are defined as fractures of the growth plate and epiphysis, or even a split of the epiphysis. The fractures extend into the articular surface of the bone and will require reduction of the joint. In distal femur fractures it may result in a growth deformity.

typeIIIfx
Type III

Type IV:

About 10% of fractures are Type IV fractures—which pass through the epiphysis, physis (growth plate), and the metaphysis. Type IV fractures can cause complications such as growth disturbance and angular deformity.

TYPEivfx
Type IV

Type V:

Type V fractures are uncommon, only occurring about 5% of the time. In type V fractures, compression or a crush injury of the growth plate takes place. This fracture has no association with the epiphysis or metaphysis and an initial diagnosis may be difficult. Despite being uncommon, these fractures have the highest incidence of growth deformity and disturbance.

typeVfx
Type V