Osteomyelitis of Long Bones

Osteomyelitis is defined as infection in bone. Osteomyelitis in long bones includes infections that differ from one another with regard to duration, etiology, pathogenesis, extent of bone involvement, and type of patient (which can be an infant, child, adult, or compromised or uncompromised host).

Etiology
In hematogenous osteomyelitis, a single pathogenic organism is almost always recovered from the bone. In infants, Staphylococcus aureus, Streptococcus agalactiae, and Escherichia coli are most frequently isolated from blood or bone.

However, in children over one year of age, Staphylococcus aureus, Streptococcus pyogenes, and Haemophilus influenzae are most commonly isolated. The incidence of Haemophilus influenza infection decreases after the age of four years.

In adults, Staphylococcus aureus is the most common organism isolated. Multiple organisms are usually isolated from bone infected as a result of direct inoculation or contiguous focus infection. Staphylococcus aureus remains the most commonly isolated pathogen. However, gram-negative bacilli and anaerobic organisms are also frequently isolated.

Pathogenesis

1. Source of Infection

Osteomyelitis can be caused by hematogenous spread, direct inoculation of microorganisms into bone, or a contiguous focus of infection. Hematogenous osteomyelitis usually involves the metaphysis of long bones in children because long bones of children have very active metabolic rates. The most common causes of direct-inoculation osteomyelitis are penetrating injuries and surgical contamination. Contiguous osteomyelitis commonly occurs in patients with severe vascular disease.

2. Host Factors

Host factors are primarily involved in the containment of the infection once it has been introduced adjacent to or into the bone. Host factors may predispose individuals to the development of osteomyelitis. Host deficiencies that lead to bacteremia favor the development of hematogenous osteomyelitis.

Host deficiencies that are involved in the direct inoculation of organisms and/or contiguous spread of infection from an adjacent area of soft-tissue infection are primarily involved in the lack of containment of the initial infection.

Some patients have an unusual susceptibility to acute skeletal infections when they have sickle cell anemia, chronic granulomatous disease, or diabetes mellitus. Many systemic and local factors influence the ability of the host to elicit an effective response to infection and treatment

Pathology

1. Acute Osteomyelitis

Acute osteomyelitis presents as inflammation accompanied by edema, vascular congestion, and small-vessel thrombosis. In early acute disease, the vascular supply to the bone is decreased by infection extending into the surrounding soft tissue. When both the medullary and the periosteal blood supplies are compromised, large areas of dead bone (sequestra) may be formed in chronic phase.

However, if treated promptly and aggressively with antibiotics and possibly with surgery, acute osteomyelitis can be arrested before dead bone presents.

2. Chronic Osteomyelitis

Pathologic features of chronic osteomyelitis are the presence of necrotic bone (sequestrum), the formation of new bone (involucrum), and the exudation of polymorphonuclear leukocytes joined by large numbers of lymphocytes, histiocytes, and occasionally plasma cells.

New bone forms from the surviving fragments of periosteum and endosteum in the region of the infection. It forms an encasing sheath of live bone, known as an involucrum, surrounding the dead bone under the periosteum.

The involucrum is irregular and is often perforated by openings through which pus may track into the surrounding soft tissues and eventually drain to the skin surfaces, forming a chronic sinus. The involucrum may gradually increase in density and thickness to form part or all of a new diaphysis.

New bone increases in amount and density for weeks or months, according to the size of the bone and the extent and duration of the infection. Endosteal new bone may proliferate and obstruct the medullary canal. After host defense or operative removal of the sequestrum, the remaining cavity may fill with new bone, especially in children. However, in adults, the cavity may persist or the space may be filled with fibrous tissue, which may connect with the skin surface by means of a sinus tract.

Views of the left wrist show a lobulated osteolytic lesion with well-defined borders and surrounding sclerosis in the distal radius. There were minimal expansion, mild periosteal reaction and soft tissue swelling.

The red box encircles the sequestrum at lower part of tibia, the piece of necrotic tissue of tibial bone, that has become separated from the tibia

Signs and Symptoms

Children with hematogenous osteomyelitis may present with acute signs of infection including fever, irritability, lethargy, and local signs of inflammation. Children with hematogenous osteomyelitis usually have noninfected soft tissue enveloping the infected bone and are capable of mounting an effective response to the infection. The joint is usually spared from infection unless the metaphysis is intracapsular, as is found in the proximal part of the radius, humerus, or femur.

Adults with primary or recurrent hematogenous osteomyelitis usually present with vague symptoms consisting of nonspecific pain and low-grade fever of one to three months’ duration. However, acute clinical presentations with fever, chills, swelling, and erythema over the involved bone or bones are occasionally seen.

The source of bacteremia may be a trivial skin infection or a more serious infection such as acute or subacute bacterial endocarditis. Hematogenous osteomyelitis that involves either long bones or vertebrae is an important complication of injection drug abuse. Patients with contiguous osteomyelitis often present with localized bone and joint pain, erythema, swelling, and drainage around the area of trauma, surgery, or wound infection.

Signs of bacteremia such as fever, chills, and night sweats may be present in the acute phase of osteomyelitis but are not seen in the chronic phase. Both hematogenous and contiguous focus osteomyelitis can progress to a chronic condition. Local bone loss, sequestrum formation, and bone sclerosis are common. Persistent drainage and/or sinus tracts are often found adjacent to the area of infection. The patient usually presents with chronic pain and drainage. If fever is present, it is low grade.

External Fixation

Case summary

36 y/o, Malay gentleman

Patient drove car with around 60km/h and was crashed with lorry from front. He was loss of consciousness and was sent to emergency department by ambulance. Multiple fractures and bleeding were noted. There was an open fracture of right leg, grade 3C in Gustillo classification. X-ray of the right leg was done.

Plain x-ray of the right leg.

This is an anterior-posterior view of distal 1/3 of right knee and proximal 2/3 of right leg. The x-ray showed that there is segmented fracture of tibial plateau, both condyles are split and the tibial shaft is wedged between them, there is intraarticular extended and was type 5 in Schatzker classification. There is no shortening, angulation or rotation of the bone was seen in this view.

This is a lateral view of distal 1/3 of right knee and proximal 2/3 of right leg. The x-ray showed that there is segmented fracture of tibial plateau, There is 10 degree angulation of the tibial bone.There is no shortening or rotation of the bone was seen in this view.

External fixation was done.

This is an anterior-posterior view of distal 1/3 of right knee and proximal 2/3 of right leg. The x-ray showed that there is a interfragmentary screw fixing the fragmented tibial bone. Two pins were passed though th femur bone and another two pins were passed through the tibial bone. There is no angulation, shortening or rotation seen in this view.

This is a lateral view of distal 1/3 of right knee and proximal 2/3 of right leg. The x-ray showed that there is an interfragmentary screw on the fragments. there is no angulation, shortening and rotation of the bone was seen in this view.

External fixation is a surgical treatment which is held by transfixing screws, pins or tensioned wires which are pass through the bone above and below of the fracture site. These are then connected to an external frame or rigid bar. While reducing the fracture in all three planes, hold it in the proper alignment (adjustment of the angulation), it also allow some degree of rigidity and stability. besides it also allow adjustment of length of the bone. External fixation is commonly apply to fracture of long bones (esp. femur, tibia and humerus) and pelvic, but it can also be used for fractures of almost any part of the skeleton (example bone of the hand). Insertion of wires and half pins must be with care, by the knowledge of 'safe corridors' is to avoid nerves or vessels injury.

Indications of external fixation include:

1. Fracture associated with severe soft tissue damage.

external fixation was apply, two pins on the femur bone and two pins on the tibia bone. there are two wounds on the anterior aspect of upper half leg. The wound is measuring 5x3cm and 5x4cm. There is bleeding, no slough, granulation tissue present, slope well-defined edge. There is no maculous pin-site infection.

2. Fracture associated with nerve and vessel damage.
3. Severely comminuted and unstable fracture
4. Non-union where dead or sclerotic fracture fragment can be excised and fragments brought together by fixator
5. Fracture of pelvic which cannot be held by other method
6. Infected fracture
7. Severe multiple injuries

Complications

1. Damage to soft tissue structures.
Surgeon must familiar with the anatomy and the 'safe corridor' to prevent injured to the nerves and vessels.

2. Overdistraction.
Fragments of the bone must come to contact for union to be occur. If there is no contact between of the fragments, union may be delayed or prevented.

3. Pin-track infection.
This is rare but is the most complicated. Therefore, meticulous pin-site care is essential. If infection is occur, administered of antibiotics must be immediate.

Type 2 Diabetes Mellitus and its related foot complications in Malaysia

Incidence of Type 2 Diabetes Mellitus in Malaysia:

In Malaysia, the First National Health and Morbidity Survey (NHMS 1) conducted in 1986 reported a prevalence of diabetes mellitus of 6.3% [1]. In the Second National Health and Morbidity Survey (NHMS 2) in 1996, the prevalence had risen to 8.3% [2]. The prevalence of diabetes had increased drastically to 14.9 per cent in 2006 for the same age group; an increase of 80% based on the Third National Health and Morbidity Survey 2006 (NHMS 3) [3]. Currently, it is estimated that one out of eight Malaysians aged 30 years and above has diabetes, which amounts to over 1.6 million adults in Malaysia. The World Health Organisation (WHO) has estimated that in 2030, Malaysia would have a total number of 2.48 million diabetics compared to 0.94 million in 2000 - a 164% increase.

Incidence of foot related complications:

Foot ulceration associated with infection is one of the leading causes of hospitalization patients with diabetes mellitus. Approximately 15% of all patients with diabetes will develop a foot or leg ulceration at some time during the course of their disease.[1-3]

Several population-based studies report an annual incidence of diabetic foot ulceration in the range of 2% to 3% in patients with either Type 1 or Type 2 diabetes, while the prevalence varies between 4% and 10%

Numerous risk factors for diabetic foot ulceration have been ascertained. Aside from the major factors of neuropathy, ischemia, pressure (trauma), and infection, multiple other contributory factors interact to produce foot lesions. Intrinsic risk factors include metabolic or biologic characteristics that may or may not be causally related to diabetes but do contribute to the aetiology of ulceration.

Symptom of diabetes:

48% of patients above the age of 30 years old are not aware that they have diabetic. The majority are asymptomatic. Patients should be aware of common symptoms of diabetes which include polyuria (increased frequency of urination), polydipsia (increased thrist), easily tired and sudden unexplained weight loss [4].

Classification diabetic foot complications
Diabetic Foot Problems are best classified according to King’s Classification [5].
Stage 1: Normal
Stage 2: High Risk
Stage 3: Ulcerated
Stage 4: Cellulitic Stage
Stage 5: Necrotic
Stage 6: Major Amputation

Post Ray’s amputation+ incision and drainage

The surgical wound located at the dorsal surface of the right foot. The wound bed consists of granulation tissues and slough. This is not a well-healing wound.

Investigations

Glycosylated hemoglobin level must be taken to obtain information of the patient’s glucose control over the past 3 months. This investigation is based on the fact that in the normal 120 day life span of the red blood cell, excess glucose molecules will react with hemoglobin, forming glycosylated hemoglobin. In individuals with poorly controlled diabetes, the level of glycosylated hemoglobins will be elevated.

Plain radiograph of foot and ankle can also be taken to make sure there is no involvement of bone to rule out osteomyelitis.

Doppler ultrasound also is significant to investigate the peripheral circulation of foot to prevent ischemia.

Diabetic Foot Care Treatment

Self-Care at Home

A person with diabetes should do the following:

• Foot examination: Examine your feet daily and also after any trauma, no matter how minor, to your feet. Report any abnormalities to your physician. Use a water-based moisturizer every day (but not between your toes) to prevent dry skin and cracking. Wear cotton or wool socks. Avoid elastic socks and hosiery because they may impair circulation.

• Eliminate obstacles: Move or remove any items you are likely to trip over or bump your feet on. Keep clutter on the floor picked up. Light the pathways used at night - indoors and outdoors.

• Toenail trimming: Always cut your nails with a safety clipper, never a scissors. Cut them straight across and leave plenty of room out from the nailbed or quick. If you have difficulty with your vision or using your hands, let your doctor do it for you or train a family member how to do it safely.

• Footwear: Wear sturdy, comfortable shoes whenever feasible to protect your feet. To be sure your shoes fit properly, see a podiatrist (foot doctor) for fitting recommendations or shop at shoe stores specializing in fitting people with diabetes. Your endocrinologist (diabetes specialist) can provide you with a refferel to a podiatrist ororthopedist who may also be an excellent resource for finding local shoe stores. If you have flat feet, bunions, or hammertoes, you may need prescription shoes or shoe inserts.

• Exercise: Regular exercise will improve bone and joint health in your feet and legs, improve circulation to your legs, and will also help to stabilize your blood sugar levels. Consult your physician prior to beginning any exercise program.

• Smoking: If you smoke any form of tobacco, quitting can be one of the best things you can do to prevent problems with your feet. Smoking accelerates damage to blood vessels, especially small blood vessels leading to poor circulation, which is a major risk factor for foot infections and ultimately amputations.

• Diabetes control: Following a reasonable diet, taking your medications, checking your blood sugar regularly, exercising regularly, and maintaining good communication with your physician are essential in keeping your diabetes under control. Consistent long-term blood sugar control to near normal levels can greatly lower the risk of damage to your nerves, kidneys, eyes, and blood vessels.

Medical Treatment

• Antibiotics: If the doctor determines that a wound or ulcer on the patient’s feet or legs is infected, or if the wound has high a risk of becoming infected, such as a cat bite, antibiotics will be prescribed to treat the infection or the potential infection. It is very important that the patient take the entire course of antibiotics as prescribed. Generally, the patient should see some improvement in the wound in two to three days and may see improvement the first day. For limb-threatening or life-threatening infections, the patient will be admitted to the hospital and given IV antibiotics. Less serious infections may be treated with pills as an outpatient The doctor may give a single dose of antibiotics as a shot or IV dose prior to starting pills in the clinic or emergency department.

• Referral to wound care center: Many of the larger community hospitals now have wound care centers specializing in the treatment of diabetic lower extremity wounds and ulcers along with other difficult-to-treat wounds. In these multidisciplinary centers, professionals of many specialties including doctors, nurses, and therapists work with the patient and their doctor in developing a treatment plan for the wound or leg ulcer. Treatment plans may include surgical debridement of the wound, improvement of circulation through surgery or therapy, special dressings, and antibiotics. The plan may include a combination of treatments.

• Referral to podiatrist or orthopedic surgeon: If the patient has bone-related problems, toenail problems,corn and callus hammertoes, bunions, flat feet, heel spurs, arthritis, or have difficulty with finding shoes that fit, a physician may refer you to one of these specialists. They create shoe inserts, prescribe shoes, remove calluses and have expertise in surgical solutions for bone problems. They can also be an excellent resource for how to care for the patient’s feet routinely.

• Home health care: The patient’s doctor may prescribe a home health nurse or aide to help with wound care and dressings, monitor blood sugar, and help the patient take antibiotics and other medications properly during the healing period.

References

1. National Health and Morbidity Survey 1986

2. National Health and Morbidity Survey 1996

3. National Health and Morbidity Survey 2006

4. Mafauzy M. Diabetes Mellitus in Malaysia. Medical Journal of Malaysia. 2006.

5. Edmonds ME and Foster AVM. Managing the diabetic foot, 2nd ed. (Blackwell, London, 2005).

Malaysia endocrine and metabolic society,Ministry of health,acdemic of medicine malaysia,Persatuan diabetic malaysia.