CHRONIC LONG BONE OSTEOMYELITIS AND LIMB LENGTH DISCREPANCY: A PROSPECTIVE SERIES OF 42 PATIENTS

Abstract

A number of series report limb length discrepancy in long bone chronic osteomyelitis, however in most cases, it is shortening of the affected bone. This is thought to be due to damage in the affected growth plate leading to early growth arrest. However, it is known that the inflammatory state of chronic osteomyelitis results in an increased blood supply and, as in other conditions such as rheumatoid arthritis, the increased blood supply results in overgrowth of the affected bone.

In order to study the effect of long bone chronic osteomyelitis on limb length, we designed a prospective trial of 42 consecutive patients presenting to our unit with chronic osteomyelitis of a long bone. The inclusion criteria were all patients presenting with a long bone osteomyelitis. There were no exclusion criteria. The mean age at presentation was 10.3 years. The mean duration of symptoms of 18.2 months prior to presentation. For 37 (88%) of patients the cause of osteomyelitis was haematogenous. On examination, 3 (7%) patients had shortening of the long bone compared to the unaffected side (of an average of 2.5cm), whilst 13 (31%) patients had overgrowth of the affected bone (average overgrowth 2.2cm). The most common bone affected was the tibia (20/42, 48%), followed by the femur (8/42, 19%) and the humerus (6/42, 14%).

All patients underwent radiographic analysis, and the average percentage of long bone affected was 59%. 8/42 (12%) of patients had at least one physis affected (2 of these patients had undergrowth and 1 had overgrowth).

This large prospective series of patients is the first in the world literature to show the effect of osteomyelitis on the growth of long bones, in particular an overgrowth rate of 31%. We suggest that the mechanism for this is related to the duration of symptoms. In areas of the world where there is poor access to health care, there is consequently a prolonged period of increased blood supply as a result of inflammation. This increased blood supply may make limb length discrepancy is more likely to be due to overgrowth rather than undergrowth.