Acute osteomyelitis

Typically, a child from a poor family living under very unhygienic conditions presents with fever and an exquisitely painful tender bone near a joint which he is unwilling to move. Or, his mother may bring him to you with fever, pain, and a limp. When you first see him the tender area will probably not yet have started to swell. Soft tissue swellling is a late sign which shows that pus has already started to spread out of the bone.

Unfortunately, many children present late after they have already sought help from traditional practitioners. Often, the history is atypical and may be misleading: (1) There may be no history of an acute illness; the first sign may be a boil-like lesion which discharges spontaneously or is incised, and which is followed by a chronically discharging sinus. (2) If an infant is very ill, he may have no fever and few general signs of infection. (3) He may have signs of a severe general infection, but few local signs. So beware of osteomyelitis in any ill child who is not using one of his limbs.

X-rays are of little help in the early stages because periosteal elevation, and bone rarefaction, which are the first signs, do not appear until after infection is established[md]if the patient is over 15 years you may not see them for 10 days. Later, you will see new bone laid down under the periosteum, and patchy rarefaction. In neonates bone changes appear about the 5th day, but even this is too late for diagnosis and treatment at the optimum time.

The only sure way to confirm or exclude osteomyelitis is to incise the periosteum and drill the bone[md]urgently. In an early case fluid under pressure comes out of the hole, but this soon becomes pus. Only if nothing comes out can you be sure that a child has not got osteomyelitis[md]in that bone. Many doctors are only used to soft tissue surgery[md]they don't like drilling bone and look upon it as specialized orthopaedics. The main message of this chapter is that you must drill urgently and early! If you don't have a surgical drill, use a carpenter's drill. Unlike acute ostemyelitis, operations for chronic osteomyelitis are never urgent, and you may be able to refer the patient.

Do your utmost to drain pus from a patient's infected bone before it has stripped the periosteum off the shaft. After this has happened, the bone can only heal by forming a sequestrum and an involucrum, with all the disability that this causes. Early treatment needs early diagnosis, so everyone who provides primary medical care must be aware of osteomyelitis. Make sure that your staff in the clinics know about it, and immediately refer any child with fever and a painful limb which is not obviously pyomyositis. Because of the common practice of giving antibiotics and seeing if the patient improves, osteomyelitis is apt to be one of the worst treated diseases in primary care. One reason why it is such an important disease in the developing world, whereas it has almost disappeared elsewhere, is that patients are so often referred to hospital late, after they have been mismanaged in peripheral units.

Any of the diseases in the list below can cause pain, fever, and inability to move a limb. Local redness and oedema are later signs. The important decision is not what the exact diagnosis is, but whether you should drill or not. The site of the greatest tenderness (at the end of a metaphysis near a joint) is a useful point of differential diagnosis, and so is the young age of the patient. The tenderness is localized and is greatest on direct pressure and percussion.

MURARULAL (9 years) was brought in by his mother with a one- day history of a limp. He was tender over his right fibula and had a mild fever, but no other signs, and no X-ray changes. The diagnosis was uncertain, so his his fibula was explored. It looked normal when it was exposed, but even so it was drilled. Pus came out under pressure. His wound was dressed and left open and he was given an antibiotic. He rapidly improved and his wound healed spontaneously. A month later he had no limp and no discharge, but an X-ray showed periosteal elevation. A year later his X-ray was normal.]] BUROO (8 years) was admitted with a swelling over the upper end of her right tibia for 4 days. A small abscess pointed. This was incised and drained. A week later an X-ray was taken and considered normal. After three months of antibiotic treatment, her wound was still discharging, and X-rays showed obvious chronic osteomyelitis. LESSON (1) If osteomyelitis is a possibility, drill the bone, especially the upper tibia. (2) Drill it even if it looks normal when you expose it. If Buroo's bone had been drilled early, she would have been spared many years of disability. (2) When you have found pus, leave the wound open. FEVER AND A TENDER BONE ARE THE CRITICAL SIGNS

DIAGNOSING OSTEOMYELITIS If a child is acutely tender over a bone, he has osteomyelitis until you have proved otherwise. If his mother tells you that he has had an injury, remember that she may be wrong, and have invented an injury to explain his symptoms. 50% of patients with osteomyelitis have a history of minor trauma to the affected limb within 14 days of the onset of infection. X- rays don't help in the early diagnosis of osteomyelitis (see above), but they will exclude a fracture.

If she complains that he is ill and is not using a limb, poliomyelitis is a possibility, but there is no swelling and no bony tenderness.

If the tenderness is in his soft tissues, rather than over a bone, he is more likely to have cellulitis or pyomyositis than osteomyelitis.

If his lower leg is swollen, oedematous, tender and warm, but the tenderness is not particularly localized over a bone, should you explore it or not? Its exact site may help you to decide. If you are still in doubt, be safe[md]drill. You will probably operate on some cases of cellulitis unnecessarily, but if you don't operate, you will miss osteomyelitis.

If the point of maximal tenderness is over a joint, not over the adjacent bone, and all its movements are exquisitely painful, he probably has a primary septic arthritis. Aspirate his joint and if necessary, drain it.

If he has fever and an acutely painful hip which he refuses to move, he has osteomyelitis of the neck of his femur with septic arthritis (they are in effect the same disease). Aspirate to confirm that pus is present (7.17). Drill his upper femur and its neck, and drain his hip (7.18).

If his muscles are swollen and tender, he probably has pyomyositis[md]feel the site of tenderness carefully.

If sickle-cell disease is common in your district, suspect that infarction of the bone which is common in this condition may be causing his symptoms if: (1) Several of his bones are involved. (2) An unusual bone is involved, such as his skull, or the small bones of his hands or feet, particularly if he is an infant. Osteomyelitis can complicate avascular necrosis, so he may have both diseases. There is no certain way of distinguishing a sickle-cell crisis from osteomyelitis except by drilling. An SS patient is usually obvious clinically, but SC patients (quite common in West Africa) are not. If he is a sickler, a wait of 24 hours is reasonable, because the pain of an infarct improves rapidly.

If lesions in his hands are causing diagnostic difficulties, remember that: (1) Tuberculous dactylitis is much less painful than sickle-cell dactylitis. (2) Syphilis will probably show abundant new bone-formation elsewhere.

If his disease is some weeks old, but there are no signs of new bone-formation on his X-ray, suspect that he has tuberculosis, or AIDS, or both. This is most likely to be a diagnostic problem in the spine. Tuberculosis usually forms no new bone, whereas chronic pyogenic osteomyelitis is more likely to. Patients with AIDS make very little involucrum.

If there is much swelling, but not much fever, suspect that he may have a sarcoma, which can mimic subacute osteomylitis and may cause fever. X-rays should distinguish it. Confirm it by biopsy.

If he has pain in many joints, he probably has a rheumatic polyarthritis. Rheumatic fever and parvovirus infections are other acute and subacute causes.

If he has any other septic lesion, such as a carbuncle or middle ear disease, suspect this may be the source of his osteomyelitis.

If the diagnosis is still difficult, consider brucellosis, yaws, syphilis, and leprosy.

Fig. 7-4 DIAGNOSING OSTEOMYELITIS. A, and B, the critical signs are fever and a painful tender bone, especially close to an epiphysis. C, the only way to confirm or exclude osteomyelitis is to drill the bone. If a patient comes when pus is already present, he is too late to be easily cured, so try to diagnose osteomyelitis [f10]before [f11]this stage.