Chronic osteomyelitis

Try to refer all patients with chronic osteomyelitis[md]surgery is difficult, bloody, and dangerous. If you have to operate, do so only to relieve persistent pain or remove persistent sinuses, not merely to improve their X-rays. You will see two kinds of disease and some intermediate forms.

(1) The common form of chronic osteomyelitis with an involucrum and sequestra is the result of neglect, or treatment which was too late in the acute stage. At the right moment, when a patient's involucrum is sufficiently formed, he needs his sequestra removed and his sinuses curetted. To do this you will either have to enlarge the existing gap in his involucrum, or you will have to cut a window in it.

If an area of bone is abnormally dense on the X-ray, showing that it is dying or dead, it may be a absorbed slowly if it is attached to existing healthy bone. But if it is lying free as a sequestrum it will it act as a foreign body and will not be absorbed, so you will have to remove it. Occasionally, you can remove a small sequestrum through a sinus, but you usually need to operate.

Don't remove a sequestrum until a patient has formed enough involucrum to make a new shaft for his entire bone. Deciding when to operate is critical. Never remove a sequestrum until an X-ray shows that removing it will not leave a gap in his bone. Once you have removed a sequestrum no new involucrum will form. This is an important exception to the general rule that a foreign body should be removed immediately, especially in the presence of infection.

How can you encourage a strong involucrum to form? Encourage him to use his limb so that the newly growing bone of his involucrum is gently stressed, without being angulated or shortened. For example, in his femur put him into a hip spica, or a cast from his groin to his knee, give him crutches and allow cautious weight-bearing.

(2)Localized chronic osteitis without an involucrum, and usually with no sequestra (Brodie's abscess), takes the form of a cavity surrounded by dense sclerotic bone, and is much less common. The patient is usually an adult with a long history of localized bone pain, most often in his upper tibia or lower femur, usually without any history of an acute phase. His pain comes and goes, and gradually gets worse. When his infection flares up he has fever and a warm, painful, tender, thickened limb. X-rays show dense sclerotic bone surrounding a translucent abscess cavity. His marrow cavity is obliterated, he has no sinuses, and seldom any sequestra.

Antibiotics are unlikely to cure him. So, if you cannot refer him, explore, curette, and if possible saucerize the cavity. This will relieve his pain dramatically. If possible, leave it open to the outside, and let it granulate from the bottom. If not, leave it open to his soft tissues. If he is unwilling to accept an operation, try antibiotics for 3 weeks only.

Closing the hole in his leg. When you have removed a sequestrum, or cleared an abscess cavity, the hole that you have left behind will have to be filled somehow: (1) If you can, try to saucerize it, which means making a nearly flat surface against which muscle will lie, and eliminate any dead space. This is ideal, but is usually impossible. (2) If saucerizing it would require removing so much involucrum that it would unduly weaken the bone, make a deeper cavity, and accept dead space filled with blood clot, even though it is liable to become infected. Close it loosely with a drain. (3) You can line a gutter you have made in the tibia with a skin graft later. Don't try to make an elaborate flap, this is an expert's task.

An alternative method of closing the wound is said to have advantages under difficult conditions. Pack it with gentamicin-impregnated polymethyl methacrylate (PMMA) beads on a string (''Streptotal' beads, E Merck). Close the wound by primary closure, leave one bead outside, and pull out the string at 10 days. Get the patient up at 24 hours and consider discharging him before the beads are removed. Drains and frequent dressings are unnecessary. H[um]o[um]ok M, Lindberg L, ''The treatment of osteomyelitis with gentamicin-PMMA beads'. Tropical Doctor, 1987;17:157. OPERATE FOR PAIN AND SINUSES, NOT FOR X-RAY APPEARANCES DON'T REMOVE A LARGE SEQUESTRUM UNTIL THERE IS A STRONG INVOLUCRUM Fig. 7-6 SEQUESTRECTOMY. A, a sequestrum is presenting through a cloaca (hole) in the bone. B, the cloaca has been enlarged and the sequestrum is being removed. Kindly contributed by John Stewart.

SEQUESTRECTOMY INDICATIONS. If possible refer the patient. If you cannot refer him, consider removing any sequestrum which you cannot remove through a sinus. Don't operate to remove a large sequestrum until: (1) The involucrum extends across the defect that will follow. (2) The involucrum is made of rigid bone. If you remove a sequestrum too early, involucrum will not form to bridge the gap. (3) His limb must be capable of being supported, either by the remaining healthy shaft, or by a sufficiently strong involucrum.

CAUTION ! If you remove the sequestrum too early the involucrum will stop making new bone, and will collapse, so that he has no hope of a sound limb.

ANTIBIOTICS. Culture the pus and give the appropriate antibiotic for at least 4 days before you operate, and for at least 2 weeks afterwards.

X-RAYS. Examine AP and lateral films carefully to see where the sequestra are. If ordinary films don't show enough detail inside the bone, take more with greater penetration.

METHYLENE BLUE may help to show up sequestra during an operation. Get it from the laboratory, sterilize a 1% solution, and inject it into the sinus 24 hours beforehand. It will stain everything blue, except the sequestra, which will remain white.

EQUIPMENT. As for acute osteomyelitis (7.5), plus 6 and 10 mm osteotomes and gouges; 10 and 15 mm chisels; a 250 g mallet, a Volkmann's scoop, a curved sequestrum forceps, and a bone nibbler. In the thigh you will need strong retractors, a strong assistant, and a good light. Sterile saline to flood the wound.

ANAESTHETIC. Ketamine (A 8.1) or general anaesthesia (A 10.1). Have blood cross matched, and a drip running.

TOURNIQUET. Bleeding can be alarming, because infected tissues are very vascular, so always use a tourniquet (3.9), unless you are operating on the patient's proximal femur or humerus, or he has sickle-cell disease (7.4). His anatomy may be very distorted, and if you don't use a tourniquet, important structures will be even more difficult to recognize. If you happen to see any vessels as you operate, tie them.

INCISION. Drape everything so as to leave only the operation site exposed. Wrap the distal part of his limb in a towel. Start by probing any sinuses to see where they go. They often go to the same place. Where possible, make one of the standard incisions described later. These are given for the entire length of the bone. You will usually only need part of an incision. Very often it will include the draining sinuses. If possible, make the incision over one of the larger gaps in the involucrum. The tissues will be tough, so use a sharp scalpel.

Open his indurated periosteum in the length of the incision, and elevate it on each side. Either: enlarge an existing gap in the involucrum with a gouge. Or: drill holes so as to outline a window, as in Fig. 7-6. Then open it with an osteotome.

CAUTION ! (1) Scar tissue may have disturbed the normal position of the nerves and arteries. (2) Don't break the bone. If you have carefully outlined the window with drill holes, this will be less likely.

Use a hammer and gouges or chisels to cut bits of bone from the involucrum until you get to his marrow cavity. Look for sequestra inside it.

Sequestra move separately from the surrounding involucrum. If they have been covered by tissues they are ivory white and have a brittle texture which is different from ordinary bone. If they have been exposed to the air they may be black or grey.

Use a hammer and gouge to chip away the involucrum around each sequestrum so that you can remove it. To minimize weakening, window the bone longitudinally. Round or taper the ends of the window; these will be stronger and allow it to fill with soft tissue more easily. Pull out sequestra with sequestrectomy forceps. If necessary, remove more involucrum to free a sequestrum. There will be pus, but usually not much.

When you have removed all the sequestra you can find, explore the abscess cavity up and down quite widely with a probe. If necessary, extend the skin incision and enlarge the hole in the involucrum until you have explored the whole cavity. Scrape the granulation tissue in its walls with a bone curette (Volkmann's spoon), until you reach healthy bone. If sinus tracts in the soft tissues are short, excise them. If they are long, curette them.

If bone overhangs the edge of the cavity, chisel it away. When necessary, flood the wound with warm saline and suck it out.

CAUTION ! (1) If the operation is to succeed, you must remove all sequestrated bone. The X-rays will suggest how much there is, but expect to find more.

CLOSURE. If possible, don't close the wound. Instead, leave it open and allow his soft tissue to fall into it, as in Fig. 7-10. Or, close the soft tissues loosely over the bone and keep the most dependent place open with a corrugated drain. Fix the drain to the wound with a stitch, because it may go inside the wound, get lost, and act as a foreign body.

If you leave the wound open, apply vaseline gauze followed by plenty of plain gauze.

If the wound is deep and large, pack it with ribbon gauze or a bandage.

Apply a pressure dressing for the first 48 hours, but watch his circulation distally. After some weeks there will be a floor of healthy granulation tissue, which will either epithelialize spontaneously, or can be grafted. As you change the dressings you will find that fewer are needed as it closes. A large wound takes a long time to close.

CAUTION ! (1) Vaseline gauze is a useful first dressing; thereafter use plain gauze. (2) Remove all the dressings you put into a wound. If any fragments remain, they will act as foreign bodies, and cause infection to persist. If you use pieces of gauze to pack a wound, knot them together, so that you can pull them all out at the same time.

POSTOPERATIVELY, the wound will ooze. If he is anaemic and ill, consider transfusing him, but remember the danger of HIV. Do all you can to improve his nutrition.

He will need quantities of sterile dressings. Change them daily at first, then twice a week, until his wound is small enough for you to treat him as an outpatient. Remove any dead tissue as necessary. Encourage him to use his limb, to walk with crutches without weight-bearing if the lesion was in the leg, and to use his arm as much as he can. In severe cases this active movement will encourage the periosteum to produce a really robust involucrum, which will not happen if he rests his limb completely.

If his involucrum might fracture, apply a cast and window it. Or, in the leg, apply skin traction. If a large area of bone has been destroyed, careful splinting is essential.

X-ray him at a convenient time postoperatively. This is only necessary to assess the strength of his leg for weight bearing, or, if sinuses persist, to look for more sequestra.

LOCALIZED OSTEITIS [s7]BRODIE'S ABSCESS This is the sclerosing type of osteomyelitis. Follow most of the steps above. Use gouges and chisels to remove enough sclerotic bone to reach the abscess cavity. Curette it, saucerize it if you can; failing this, leave it with gently sloping edges. Pack the medulla with sterile gauze as described above.

DIFFICULTIES [s7]WITH CHRONIC OSTEOMYELITIS If he BLEEDS SEVERELY into his dressings, take him back to the theatre, open the wound, tie off any bleeding vessels, repack it tightly, and apply a pressure bandage. Back in the ward raise his limb, and put a cradle over it, so that you can inspect it readily. Don't leave a pressure dressing in place for more than 48 hours, or it will promote infection.

If PUS CONTINUES TO DISCHARGE from his wound it may be due to: (1) Inadequate excision of fibrous tissue and curettage of the granulations. (2) Leaving sequestra behind. (3) Leaving a swab or piece of dressing or vaseline gauze in the wound. (4) Not opening up the cavity in the bone widely enough.

If his leg has united in a DEFORMED POSITION, accept it if you can.

If he has a PATHOLOGICAL FRACTURE, splint his limb in the correct position in a cast until it has healed soundly. While it is healing pay special attention to the alignment of his knee and ankle. Keep the wound open, dress and toilet it regularly. Skin traction is suitable for the femur and upper tibia, especially under the age of 14. Bone traction is contraindicated because you should not put a pin through bone if there is infection nearby. This may be unavoidable if there is significant shortening (unusual).

If you are wondering if AMPUTATION is justified, refer him for a second opinion before you do so. It may be indicated if: (1) The infection is so extensive that antibiotics and surgery have been unable to cure him. (2) So much bone has to be removed that his leg would work better with an amputation and a prosthesis. (3) His life is in danger from infection. (4) He is in constant pain.

If osteomyelitis has followed the ILL-ADVISED APPLICATION OF A PLATE, remove it. The only exception is an AO compression plate. If this is still maintaining compression, leave it. If it is holding a gap open between the fractured ends, remove it.

If he is an INFANT, his bone will probably heal well, even after you have removed a large sequestrum. If an operation is needed, don't hesitate to operate as soon as a satisfactory involucrum has formed.

If he has SICKLE-CELL DISEASE, he is likely to form new bone particularly slowly.

If he has ARC, (he is HIV-positive with weight loss and lymphadenopathy), he may have an unusual type of low-grade slowly progressive and sometimes multiple osteitis, with little sclerosis or involucrum and no large sequestra. Infection may spread from his tibia through his knee to his femur. Antibiotics have little effect, and you will probably have to amputate.