Tuberculous Dactylitis – Spina Ventosa

Boyer is credited with the first anatomical description of spina ventosa (spina = short bone;

ventosa = inflated with air) in the short long bones in 1803,

Case Report :

A 7 year-old male was brought with complaint of draining sinus from the dorsal aspect

of right hand. Initially he had pain in right hand five months back for which symptomatic

treatment was given, following which he developed a soft tissue swelling in the hand. After a trivial trauma pus started discharging from the involved site. Despite broad spectrum antibiotic therapy, there was no clinical improvement.

Discussion :

Skeletal tuberculosis is relatively uncommon compared to the pulmonary form of tuberculosis. Only 1/3rd of patients with bone tuberculosis are diagnosed with concomitant active pulmonary disease. In fact, bones and joints are affected in 1%–3% of all cases and the spine and the hip are most commonly involved. It occurs in 1–5% of children who have untreated initial pulmonary TB. The incidence of tubercular dactylitis among children with TB is reported to be 0.65-6.9%. The bones of the hands are more frequently affected than bones of the feet. In the feet, the calcaneus is the bone most commonly involved. In infancy and childhood before the epiphyseal centres are well established, the hematopoietic marrow in the short bones offers a fertile field for hematogenous bacterial implants. The infection rapidly involves the entire marrow space. Tuberculous granulation tissue expands the relatively soft cortex as it is resorbed or infarcted by the underlying process. The resultant fusiform expansion of the bone with thinned cortex and relatively radiolucent marrow space due to trabecular destruction resembles an inflated balloon. Typically, there is no periosteal layering or thickening, and sequestration ordinarily does not occur. Sclerosis may be seen in long standing cases. In natural course, the disease heals with shortening of the involved bone and deformity of the neighbouring joint. The condition usually presents as a painless swelling of a digit of few months’ duration. The main differential diagnoses include sickle cell dactylitis which exhibits features similar to that of tubercular dactylitis but is characteristically bilateral and dissolution of the sickle cell lesions is typically followed by irregularly sclerotic new bone formation. Other differential diagnoses are congenital syphilis, pyogenic osteomyelitis, fungal infections and tumors. In syphilis, the bone is thickened by periosteal reaction. Clinically, pyogenic osteomyelitis tends to be acutely painful, swollen, and hot, with generalized fever. Tuberculous osteomyelitis is more often only mildly painful, pyrexia is minimal, and the whole condition is relatively benign.

Diagnosis of tubercular dactylitis is made on radiographic features as explained above and culture of Mycobacterium tuberculosis. As it is a paucibacillary lesion, it becomes difficult to demonstrate or culture acidfast mycobacteria from these lesions. However, the gold standard for the diagnosis of osseous tuberculosis is culture of Mycobacterium tuberculosis from bone tissue. The significance of a history of trauma, reported by one third of patients, is unknown. Pulmonary tubercular involvement is uncommon in cases of tubercular dactylitis. In endemic regions, the clinical features, radiological appearance and elevated ESR are sufficient to diagnose tuberculosis and begin treatment. Management is essentially by antitubercular drugs, rest to the involved part in functioning position and early active exercise1. Current recommendations for the treatment include a two month initial phase of Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol followed by a six to 12 month regimen of Isoniazid and Rifampicin. Few studies argue that six month of antitubercular treatment is appropriate for tubercular dactylitis because of its paucibacillary nature.