Exploring a bone for pus

If you suspect that a patient has osteomyelitis, the critical procedure is to drill his painful tender bone. There is little point in aspirating it first, except sometimes to localise the site, because you will have to drill it anyway, even if aspiration is negative. If you don't find pus, or tissue fluid under pressure when you drill, you can now be sure he has not got osteomyelitis in that part of that bone, and you have done him no harm.

Although a single drill hole will drain a small abscess, it will not drain a large one, so if your drill finds pus, drill a line of at least three staggered holes at least 1 cm apart in the length of his bone. If you find pus under his periosteum, you may find that it has made its own hole in the bone: if this is big enough there is no need to drill.

NEVER HESITATE TO DRILL FOR PUS

EXPLORING ACUTE OSTEOMYELITIS INDICATIONS. Operate on any patient, particularly a child with a history of 48 hours or more of fever and a painful bone.

EQUIPMENT. A general set (4.12). One light-toothed dissecting forceps. One light plain dissecting forceps. Four light bone levers. Four heavy bone levers. One periosteal elevator. A bone drill, or a carpenter's twist drill with a 4 mm bit: don't use a smaller one.

ANAESTHESIA. Mark the tender area on his skin before you anaesthetize him. Give him ketamine or a general anaesthetic. If he is a sickler, give him 50% oxygen, make sure that he wakes quickly postoperatively, and leave an airway in until he is fully awake.

A TOURNIQUET should always be used, if the site makes it possible[md]see Section 7.4.

INCISION. Expose his bone on either side of the point of greatest tenderness. Try to incise over a bony surface which is covered with muscle, rather than one which is covered only with skin. Make the incision long enough, and start it at the epiphysis. Incise his oedematous subcutaneous tissues.

If you find pus in his muscles away from the bone, don't automatically think that he has pyomyositis. Explore deeper by blunt dissection and make sure that the pus is not arising in his bone, and has escaped into his muscles. If the pus is close to the bone, it is probably coming from a subperiosteal abscess. Use bone levers to retract his soft tissues.

If you don't find pus in his muscles, continue your incision down to the periosteum. Incise it longitudinally.

If pus immediately floods up from under his periosteum, there are three possibilities: (1) If there is no obvious hole, drill; it will help drainage. (2) If there is a big hole, the bone is already adequately decompressed, so there is no point in drilling. (3) If there is a small hole, drilling may help pus to drain.

Drill a minimum of 3 holes into the bone in a lazy zig-zag line, starting about 1 cm from the epiphyseal line and at least 1 cm apart. Make a separate small incision in the periosteum for each drill hole. Drill vertically, not obliquely, because drilling will be easier. If no pus or tissue fluid under pressure comes out, he has probably not got osteomyelitis[md]provided you really have drilled the tender area.

If pus flows from the first hole, send a specimen for culture. Drill two or more holes 1 cm apart in a lazy zig-zag line down the shaft of his bone until only blood or tissue fluid flows out of the hole from healthy bone.

Close most of the wound loosely with a corrugated drain, in the most dependent part of the wound.

CAUTION ! (1) Don't elevate his periosteum, because the bone under it will die. (2) Don't elevate too much muscle either, because periosteum receives its blood supply from the muscles over it. (3) Don't incise his periosteum beyond his epiphyseal line, or you may spread the infection to his epiphysis. (4) Don't remove any periosteum, because the bone under the raw area will not regenerate. (5) Never drill a row of holes across a bone, because they weaken it. (6) A single drill hole will not drain an abscess sufficiently.

POSTOPERATIVELY, if there is any danger that the bone might break, apply a plaster gutter splint. In his lower femur or upper tibia, apply skin traction. If his limb is painful, elevate it.

If at 2 weeks, the lesion is clinically quiescent, and X- rays show no bone necrosis, stop antibiotics. Otherwise continue them for a maximum of 6 weeks. Follow him up for 3 months; if his X-ray is normal then you need not see him again.

CAUTION ! If the bone is very osteoporotic, apply a cast before he is discharged to prevent a pathological fracture, especially if his leg is involved.

DIFFICULTIES [s7]WITH ACUTE OSTEOMYELITIS If a child has X-RAY CHANGES WHEN YOU FIRST SEE HIM, chronic osteomyelitis will follow. Proceed as above: pus in his tissues or under his periosteum will need draining. If, when you open his periosteum, you cannot see any obvious holes in his bone, drilling it will still be useful.

If he is UNDER 6 MONTHS, osteomylitis arising in the metaphysis is inevitably complicated by septic arthritis. Drain the joint also. Bone necrosis is less likely, because the arteries are not end arteries.

Fig. 7-5 UNTREATED OSTEOMYELITIS. A, late osteomyelitis of the knee with a severe valgus deformity. B, destruction of the humerus causing angulation, combined with contractures of the elbow and wrist. C, osteomyelitis in several joints. This patient could run with simple boots after his exostosis had been excised, and both his Achilles tendons had been lengthened. So save a patient's limb if you possibly can: amputation is almost always avoidable. Kindly contributed by Ronald Huckstep.