Tuberculosis (TB) is a contagious infectious disease, causing about 1.7 million deaths each year. With the introduction of the first TB vaccine in 1924, the severity of the disease diminished greatly in modern countries. Despite the decline, TB infection has increased recently with the advent of drug-resistant strains and the rise of HIV (World Health Organization 2006).

Because bone reacts in a limited number of ways to disease, interpreting skeletal lesions can be extremely complex. Nevertheless, Eyler et al (1996) reported that “the most common condition associated with rib enlargement was pulmonary TB”. There is a disparity in the reported rate of skeletal lesions from TB in recent studies; Kelley and Micozzi (1984), using the Hamann-Todd Collection in Cleveland, found that 8.8% of individuals who died from TB displayed rib periostitis on the visceral (interior) rib surface. Santos and Roberts (2001, 2006) reported a much higher frequency in the Coimbra Collection in Portugal: 90.9% of juveniles and 85.7% of adults with pulmonary TB presented rib periostitis.

This study will expand on the work of previous authors on the diagnosis of tuberculosis in skeletal remains. The frequency of rib lesions in individuals with pulmonary TB will be compared to those who died from general tuberculosis and those from a non-tuberculosis disease. An additional facet of this research is quantifying and evaluating the concomitant occurrence of rib and spine lesions.

Materials and Methods

The individuals studied are part of the Robert J. Terry Anatomical Skeletal Collection, housed at the National Museum of Natural History in Washington, D.C. The collection began in early 20th century, acquired from St. Louis hospitals and morgues for use in cadaver research. The 1,728 individuals in the Terry Collection are well-documented, with cause of death and pathological conditions for each on file.

• Age at death of sample ranged from 17 to 84 years

• Sex and ancestry were recorded as 104 males and 46 females, with 102 Blacks, 45 Whites, and 3 Asians

• Sample was clustered into three groups according to reported cause of death: 50 who died from pulmonary tuberculosis, 50 from general (non-specific) tuberculosis, and 50 from a non-respiratory disease

• The individuals were randomly-selected from each subgroup

The focus of study was inflammatory changes, osteoblastic and osteoclastic activity, to the visceral surface of the ribs and to the anterior bodies of the vertebrae.

• Bones were examined under a magnifying lamp

• Cause of death was not known at time of examination

• Changes quantified according to following morphological range:

“0” normal bone with no visible change

“1” mild periostitis, or new growth, and/or osteolytic lesions

“2” moderate periostitis and/or osteolytic lesions

“3” extensive periostitis and/or osteolytic lesions

• Quantity and location of the vertebral and spinal lesions recorded

Results and Discussion

Frequency of Rib and Spine Lesions

66% of individuals dying from pulmonary TB, 62% of those from non-specific TB, 16% of those from a non-tuberculosis disease had new bone formation on their ribs. The differences were highly significant (P<0.0001, P<0.001, respectively).

38% of the pulmonary TB, 36% of the non-specific TB, and 8% of the non-tuberculosis individuals demonstrated lesions on both the ribs and vertebrae, which was highly significant (P=0.0004, P=0.0007, respectively).

Other Studies on Rib Lesions

The results of the Roberts et al (1994) study on the Terry Collection are not significantly different from the results of the present study (61.6% versus 66% for pulmonary TB; 61.9% versus 64% for all TB; and 15.2% versus 16% for non-TB individuals).

Comparisons between Santos and Roberts (2006) study on the Coimbra Collection required the restriction of present study sample to individuals below 40 years since the Coimbra Collection is comprised of younger aged individuals. The current study, under 40 only, revealed no significant differences to the Santos and Roberts results.

The Santos and Roberts (2001) study was done only on juveniles, aged 7-21. Although the reported frequencies are similar to those of the under 40 group in the current study, the sample sizes are too small to test for significance.

The higher incidence of lesions in younger individuals would likely be attributable to the more virulent nature of the tuberculosis infection in younger adults, causing the lesions on the ribs but also killing the host relatively fast. In older individuals, a more chronic pattern would be seen.

Diagnosis of TB from Skeletal Remains:

Since bone will only respond to infection in three major ways, observed bony lesions can have differential diagnoses. Thus, a greater assessment of lesion distribution in the skeleton is necessary to accurately determine the disease causing the bony response.

Many individuals in the Terry Collection are reported to have died from non-specific tuberculosis. Considering that pulmonary TB accounts for at least 70% of all cases (Santos and Roberts 2006), some may have certainly died from the pulmonary form but this was not specified in the cause of death.

Some portion of the non-TB sample may have also been victim to tuberculosis, which lead to the death of the individuals by decreasing their immunity to other more acute illnesses, such as pneumonia, or from other complications, such as heart congestion.

Further study:

To better understand the interaction of tuberculosis on the spine and the ribs, especially between the sexes, a greater number of individuals need to be sampled to allow for more significant comparisons. Refinement of the stages of lesion expression and recording of other lesions in the skeleton need to be made to evaluate the severity and extent of skeletal lesions as related to pulmonary versus extra-pulmonary tuberculosis.

References

Eyler W, Monein L, Beute G, Tilley B, Shultz L, Schmitt W. 1996. Rib enlargement in patients with chronic pleural disease. Am J Radiol 167:921-926.

Kelley M, Micozzi M. 1984. Rib lesions in chronic pulmonary tuberculosis. Am J Phys Anthropol 65:381-386.

Roberts CA, Lucy D, Manchester K. 1994. Inflammatory lesions of ribs: an analysis of the Terry Collection. Am J Phys Anthropol 95:169-182

Santos AL, Roberts C. 2001. A picture of tuberculosis in young Portuguese people in the early 20th century: a multidisciplinary study of the skeletal and historical evidence. Am J Phys Anthropol 115:38-49

Santos AL, Roberts C. 2006. Anatomy of a serial killer: differential diagnosis of tuberculosis based on rib lesions of adult individuals from the Coimbra Identified Skeletal Collection, Portugal. Am J Phys Anthropol 130:38-49

World Health Organization. Tuberculosis. March 2006. http://www.who.int/mediacentre/factsheets/fs104/en/

This research was supported by the Notre Dame Internship Program in Anthropology.