Diagnostic challenges and eponyms in tuberculous arthritis

We read with interest the case series by Luo et al., which documented cases of tuberculous arthritis involving the hip and knee [1]. Notably, two of the patients in this series lacked overt risk factors typically associated with an increased risk for tuberculosis. Diagnosing tuberculous arthritis in a joint can be challenging and is often not initially considered in patients presenting with monoarticular arthritis, leading to delays in diagnosis and increased morbidity [2]. Physicians may not always consider or assess for factors that predispose patients to tuberculous arthritis. Furthermore, the absence of pulmonary manifestations, along with nonspecific symptoms and an indolent disease course, further complicates and delays recognition and diagnosis.

Three eponymous signs – Phemister, Gauvain, and Hefke-Turner – are notable in cases of monoarticular arthritis. Although not discussed by Luo et al., we believe it is important to remind physicians of these physical examination signs and findings, which are useful in diagnosing monoarticular arthritis. These bedside tools can be valuable in facilitating and expediting diagnosis at an early stage of the disease.

Dallas B. Phemister (1882–1951) described specific radiographic findings in joints affected by tuberculosis. In joints such as the hip and ankle, where articular surfaces remain in contact, radiographs show “regional bone atrophy, reduction or loss of density of the shadow of bony articular cortex, and preservation of the normal width of the cartilage space of the joint.” (p.750–751) [3]. In contrast, in joints like the knee and shoulder, where there are areas of non-contacted cartilage, radiographic findings include:

[R]egional bone atrophy, diminution or loss of the shadow of bony articular cortex in non-contacted regions and preservation of the shadow of boney articular cortex of the cartilage space in the contacted region of the condyles and tuberosities. Eventually the entire articular cartilage may be destroyed. This results roentgenologically in a narrowing or complete loss of the cartilage space of the joint (p.751) [3].

This latter pattern is often referred to as the “Phemister triad” [4], characterized by juxta-articular osteopenia and/or osteoporosis or regional bone atrophy, peripheral osseous erosion involving the boney articular cortex in contacted regions, and gradual narrowing of the joint space [3,4].

Sir Henry J. Gauvain (1878–1945) described a physical sign in 1918, indicating spasms of the muscle involving and surrounding the hip joint as an early indicator in patients with tuberculosis [5]. The sign is elicited as follows:

If the femur, on the affected side, be grasped firmly in the region of the condyles it will be found that the head of the bone may be gently rotated within the acetabulum, either inward or outward, through a varying but often considerable angle. When this movement is checked but the disease remains active, a further slight sharp rotation is instantly followed by spasmodic muscular contraction, not confined to muscles about the joint but extending to the abdomen and visible in the abdominal muscles, or still more easily demonstrated in the palm of the hand is placed on the abdomen between the iliac spines. Quite a gently and painless but sharp rotary movement is sufficient to provoke this reflex spasm of the abdominal muscles (p.666) [5].

Hans W. Hefke (1871–1964) and Vernon C. Turner (1907–1959) described the radiographic appearance of the hip in patients with tuberculosis in 1942, which they termed the “obturator sign”:

The obturator sign consists in a widening and a change in the contour of the normal obturator shadow. This widening may be from slight to very marked and four gradations, from 1 to 4, have been made more or less arbitrarily. Grade 2 was considered to include those cases in which the shadow was approximately twice the normal width; Grade 4, more than four times the normal; and Grades 1 and 3 were placed correspondingly. In most instances the opposite hip may be taken as the normal. In a very small number of cases it was noted that the obturator shadow was obscured. It was impossible to determine the border of the shadow because of haziness. After making the study the conclusion was reached that an obscured obturator shadow is a positive finding indicative of hip-joint pathology (p.861) [6].

Compared to patients with septic arthritis, the obturator shadow in patients with active tuberculosis of the hip is more obscured or widened, rather than presenting as a bulge with sharp, curved margins.

Tuberculous arthritis is a rare manifestation of extrapulmonary tuberculosis. Three diagnostic clues – two radiographic signs (Phemister and Hefke-Turner) and one physical examination sign (Gauvain) – are associated with tuberculous arthritis. Although the sensitivity, specificity, and clinical utility of these signs and the triad are not yet well-established, raising awareness among physicians is crucial. Further studies are needed to define their clinical application and validate their use in routine practice.

Funding

None.

CRediT authorship contribution statement

Jacob Draves: Writing – review & editing, Writing – original draft, Conceptualization. Halil Tekiner: Writing – review & editing, Writing – original draft, Conceptualization. Steven H. Yale: Writing – review & editing, Writing – original draft, Conceptualization. Eileen S. Yale: Writing – review & editing, Writing – original draft, Conceptualization.