Tuberculous osteomyelitis of tibial diaphysis following saphenous vein graft harvest for coronary artery bypass: a case report

Abstract

Tuberculosis in the tibial diaphysis following saphenous vein graft harvest for coronary artery bypass grafting has not been reported, to the best of authors’ knowledge. We report the first such clinical case in view of its clinical rarity and as a complication of the simple procedure like saphenous vein graft harvest.

Introduction

Tuberculous infection occurring after a surgical procedure, especially in the setting of no past history or current evidence of this infection, is a rare entity. It has been proposed that Mycobacterium may involve an implant site possibly by hematogenous spread from activation of a latent distant focus or local reactivation of dormant bacteria in a previously exposed individual [1]. Such tuberculous infection, often referred to as implantation tuberculosis, is an atypical presentation. This entity is reported in the literature mostly following fracture fixation [1–4]. Sternal tuberculosis following coronary artery bypass grafting (CABG) has also been reported sparsely [5]. Implantation tuberculosis in the tibial diaphysis following saphenous vein graft harvest (SVGH) for CABG has not been reported, to the best of the authors’ knowledge as a PubMed search with MeSH Major Topics of “tuberculosis,” “tibia diaphysis,” “cardiac surgery,” and “saphenous vein graft harvest” did not reveal similar publications. We report the first such clinical case in a 60-year-old gentleman, who underwent CABG at another center for coronary artery disease (CAD). The case is presented in view of its clinical rarity and as a complication of the simple procedure like SVGH. We also discuss the pathogenesis of the condition, and possible measures to avoid this complication. The patient was informed that data concerning the case would be submitted for publication, and written informed consent authorizing the radiologic examination and photographic documentation was obtained.

Case report

A 60-year-old gentleman presented to orthopedic outpatient department with a painful swelling and pus discharge from the middle-third of his left leg for the past 21 months. The swelling was insidious on onset that started approximately 3 months after CABG procedure for CAD that was performed at another institute. The leg was apparently normal before the CABG procedure. The pain preceded the swelling by 1 month. The pain used to aggravate on prolonged standing and exertion and relieved on taking rest or analgesics. The pain was a dull aching in nature. It used to persist throughout the day and was perceived more during the nighttime. He noticed pus discharge from the distal extent of swelling around a month later. It was scanty and had a yellowish-white color. There was no history of passage of bone pieces from the discharge. During these months, he never developed high grade fever or extremely tender, hot swelling in the leg. He was being managed by regular antiseptic dressings by a local practitioner since then. There was no past history of tuberculosis or its close contacts. On examination, the vitals were stable. There was no evidence of lymphadenopathy. His physical status was good. Local examination revealed a tender, oval, well-defined, indurated swelling of 4 cm × 4 cm × 3 cm in the middle-third of the shin with skin discoloration around it (Fig. 1). A sinus with scanty discharge was present over its infero-medial aspect. Local temperature was marginally raised. There was no fluctuation. There was a linear primarily healed surgical scar of the previously harvested saphenous vein for CABG on the medial aspect of the leg which was passing over medial margin of swelling and the sinus tract was opening on it. The tibia was thickened and irregular surrounding the sinus. The rest of the organ systems (respiratory system, abdomen, nervous system) appeared normal on clinical examination.

Fig. 1.

Clinical photograph of the leg showing an oval swelling (marked with dotted oval) of approximate size 4 cm × 4 cm × 3 cm on the middle-third of the shin with surrounding skin discoloration. A sinus is also seen over its infero-medial aspect (horizontal arrow). A linear primarily healed surgical scar of the previously harvested saphenous vein for the coronary artery bypass is visible on the medial aspect of the whole leg (marked with dotted line). Vertical upward arrow is pointing toward the knee

Routine blood investigations were within normal limits except increased lymphocytes (42%) and erythrocyte sedimentation rate (ESR) (62 mm). Pus culture showed the growth of contaminants. Chest radiograph and high-resolution computed tomography (CT) were normal. Ejection fraction was 45%. Leg radiographs revealed a geographic intracortical lytic lesion in the tibia in its middle-third (Fig. 2a, b). The lesion had sclerotic rim and contained radio-opacity within it, possibly representing a sequestrum. Medial soft tissue shadow displayed multiple surgical staples that were possibly used for securing the tributaries of the saphenous vein. The sinogram established a continuity of the sinus with the underlying tibia (Fig. 2c). CT revealed a geographical lytic lesion in the antero-medial surface of the tibia that had communication with the medullary cavity in its distal aspect and contained a loose bony fragment within it (Fig. 3a, b). A provisional diagnosis of chronic osteomyelitis of the left tibia was made and the patient was classified according to Cierny and Mader staging system [6] as stage IIIB^L (anatomical type III, “localized” as cortical sequestrum that could undergo excision without compromising the bone stability; physiological class B host, “compromised” as skin condition was thought to delay wound healing). The patient underwent sinus tract excision, debridement, and sequestrectomy after utilizing previous scar and raising medial subperiosteal flap. The sequestrum was surrounded by thick caseous material. The sinus tract and infected tissues were removed and freshening of the cavity walls was done with high-speed burr. Thorough lavage was done with copious saline. The lesion was not considered to be compromising the bone strength of the tibia significantly; hence, fixation was not performed.

Fig. 2.

(a) Antero-posterior and (b) lateral view radiographs of the leg showing a geographic intracortical lytic lesion in tibia in its middle-third that has sclerotic rim and contains sequestrum. Multiple surgical staples of the previous surgery for securing the tributaries of the saphenous vein are seen in the medial soft tissue shadow. (c) Sinogram revealing the continuity of the sinus with the bony lesion

Fig. 3.

Computerized tomography of the leg: (a) sagittal and (b) axial views showing the intracortical lytic lesion predominantly involving the antero-medial surface of the tibia and communicating with the medullary cavity in its distal aspect and containing the sequestrum within it

The pus culture report was negative for pyogenic organisms. Acid fast bacilli were not demonstrable on Ziehl-Neelsen staining. Smear microscopy revealed the presence of necrotizing epithelioid granulomatous reaction and Langerhans giant cells. Polymerase chain reaction (PCR) for Mycobacterium tuberculosis was positive. Later, culture was also found to be positive for Mycobacterium tuberculosis.

The patient was initiated on standard multidrug antitubercular chemotherapy (isoniazide(H) 5 mg/kg; rifampicin(R) 10 mg/kg; pyrazinamide(Z) 25 mg/kg; ethambutol(E) 15 mg/kg; along with pyridoxine 10 mg). The alternate day drug therapy consisted of an intensive phase isoniazid, rifampicin, pyrazinamide, ethambutol (HRZE) for the initial 2 months, and a maintenance phase isoniazid, rifampicin (HR) for the next 4 months. The wound took 4 weeks of regular anti-septic dressings to heal. The pain subsided over the next 6 weeks. He was asymptomatic when contacted by telephone at the 12-month follow-up. He passed away 15 months later while asleep.

Discussion

Tuberculous osteomyelitis of the tibial diaphysis is reported for its rarity and as a complication of the SVGH in a 60-year-old gentleman, who underwent CABG 2 years ago and developed swelling and discharge from the leg 3 months later. The diagnosis was established by clinico-radiological correlation and pathological findings. The lesion was healed following sequestrectomy and antituberculous chemotherapy.

Infections following surgery are primarily considered to be pyogenic in nature. A high index of suspicion is usually required to consider the possibility of non-pyogenic infections. The condition may remain undiagnosed for months or even years, which contributes significantly to the morbidity [1–5, 7, 8]. “Implantation” tuberculosis is one such rare entity and has been reported sparsely in the literature. This entity has been reported in literature following fracture fixation in both closed [1–4] and open cases [1, 4], sternotomy fixation in open heart surgery [5], prosthetic joint infection [7], and arthroscopic anterior cruciate ligament reconstruction [8]. Implantation tuberculosis of tibial diaphysis following SVGH is exceedingly rare and such a case has not been reported before.

Infection of the diaphyseal region of long bones is otherwise a rare entity [9]. Such atypical presentation in our skeletally mature patient evoked a suspicion in our minds for probability of a postoperative infection. Moreover, it became clinically evident 3 months following surgery. The etiological diagnosis in such cases is established by biopsy and cultures and usually proves to be pyogenic in nature. In light of the above facts, we considered the probable diagnosis to be chronic pyogenic osteomyelitis. To our surprise, intra-operative features and the histopathological features were consistent with tuberculous infection. A retrospect insight suggested that the correct diagnosis could have been considered preoperatively also. Radiographs showed cortical localized diaphyseal osteomyelitis of the medial subcutaneous surface of tibia. India is an endemic zone for tuberculosis and total tuberculosis (TB) incidence is 26,90,000 (highest figures in the world), the rate being 136–273 cases/100,000 population [10]. With such a high burden, there may be a possibility that operating rooms may also harbor Mycobacterium strains which may infect the operating wounds. Such an implantation may lead to a clinical infection in due course especially in vulnerable patients. Contributory factors in our patient were old age and low immunity following stress of major cardiovascular intervention.

The “implantation” osseous tuberculosis has been reported in literature following bony surgeries only [1–5, 7, 8]. Our patient underwent a soft tissue procedure of SVGH and subsequently developed this bony infection. In our opinion, the development of osseous tuberculosis following a soft tissue procedure could be possible because of faulty closure of the surgical wound. Since the medial surface of the tibia is subcutaneous, the periosteum could have been accidentally taken in the suture bite during the subcutaneous layer closure of the saphenous vein graft harvest site. The infection of this suture material would have extended the infection to the surface of the bone. Though our hypothesis remains conjectural, it, theoretically, supports the development of diaphyseal cortical localized osteomyelitis of the medial subcutaneous surface of the tibia. Isolated involvement of the antero-medial cortex of the tibial diaphysis along the line of the previous incision scar seems to be in favor of Mycobacterium being inoculated during the surgical procedure, rather than coming from the hematogenous route as such a spread would have caused medullary infection of the bone [9].

The evacuation of abscesses and sequestrectomy, an operative treatment similar to that for chronic pyogenic osteomyelitis, is required for the effective treatment in addition to antituberculous chemotherapy [9]. Wounds in tuberculous osteomyelitis may be closed primarily unless it is complicated by a secondary pyogenic infection. Our patient did not require additional soft tissue procedure. However, the wound took 4 weeks of regular dressings to heal as anticipated because the pocket of pus over the middle-third of the shin adjacent to the sinus would have compromised the vascularity of overlying skin.

To summarize, implantation tuberculosis of the tibial diaphyseal following a soft tissue procedure is an extremely rare complication. The authors aim to present the clinical course of this rare entity to make orthopedic surgeons aware of this possibility.

Funding

They did not receive grants from any commercial entity in support of this work.

The manuscript has been read and approved by all the authors and requirement for authorship of this document has been met. Each author believes that the manuscript represents honest work.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Informed consent

A written informed consent was obtained from the patient authorizing radiological examination, photographic documentation, and surgery. He was also informed that the data concerning the case would be submitted for publication and he consented.

Human and animal rights

There were no infringements of human/ animal rights in this investigation.

Ethical committee approval

Since this is a case report, we didn't take the ethical clearance as there was no change in the treatment protocol.