Tuberculosis of Bone & Joints

Pathogenesis

The lower half of the upper vertebra and the upper half of the lower vertebra and the disc, they arise from the same mesodermal somite. Thus they have the same segmental artery supplying it. So, the tubercular bacilli always involves two vertebrae and one disc called as para discal lesion. It's also called a disease involving bone and the cartilage. TB involves the vertebral body, which is anterior to neural tissue. So, it's an anterior disease. Single vertebra and posterior elements involvement is not TB. The vertebra, the pedicles, lamina, spinous process or the transverse process, all these are called as the posterior elements of the spine.  

Paradiscal Lesion

Spinous processes are rare but the rarest is Facet joints. 

Pott's Spine

Is a 2 vertebral disease, involves vertebra and disc, bone and cartilage, paradiscal and its anterior disease. Posterior elements and single vertebral disease is malignancy. In the spine most commonly involves the dorsal lumbar spine, or dorsal lumbar junction (D₁₁-D_{12 and} L₁)

Winking Sign

Every vertebra has 2 eyes and one nose. Whenever malignancy destroys vertebra, firstly it affects the pedicle (one eye). When one eye is gone, it is called as winking owl sign. When both the eyes are gone , it is called blind bat sign. 

Aneurysmal Sign

It means abscess erodes the vertebra. 

Pott Spine Clinically

First symptom is back pain. First sign is tenderness. First neurological sign is an increased deep tendon reflex. 

• Weakness in the lower limb
• Bowel bladder involvement
• >50% sensory loss
• Xray and MRI shows paradiscal lesion

Treatment 

Anti tubercular therapy plus surgery (when indicated). Rifampicin is the drug of choice. For bacterium tuberculosis, combination therapy is the best. 

Middle Path Regimen (surgery when indicated)

Indications of surgery

• Bowel bladder involvement
• In Spite of treatment , patient is worsening
• Not improving

Surgery

The disease is on the anterior side, so the approach is to enter from the left side. There are 2 approaches

• Anterolateral decompression + bone grafting.
• Anterior decompression + bone grafting
• Never touch posterior elements in Pott's spine

Good Prognostic Factors

• Young age
• Early disease
• Active disease
• Slow worsening
• Normal spinal cord (First involvement is motor, than sensory, than urinary)

Prognostic factors for TB spine

Cobra Plate Is Used For Hip Arthrodesis

• Arthrodesis-  Surgical fusion-bony-painless. Not a preferred surgery
• Ankylosis- pathological fusion of a joint
• Fibrous Ankylosis-painful-TB hip and knee/ Rheumatoid arthritis
• Bony Ankylosis-painless-septic arthritis>TB Spine/AS

Joint Replacement

Insert implant inside the bone directly. The bone will grow over the porous elements and attains a very strong implant bone contact called as uncemented replacement or can have layers of cement between the implant and the bone called as cemented replacement. 

Hemiarthroplasty

Only the femoral part with the head and the neck is half replacement. When replaced half, it can be 2 types

1. Austin Moore- It has 2 holes
2. Thompson Prosthesis- Has no holes

Total Hip Replacement

When replace acetabulum along with femur

Complications of THR

• Infection
• Dislocation
• High mortality- Myocardial infarction> cardiac respiratory arrest (PE- Thrombolysis)

Metal Associated Complications

• Hypersensitivity
• Renal insufficiency
• Teratogenicity
• Chromosomal abnormalities
• Carcinogenesis

Babock’s Triangle

Osteopenic area in between trabeculae is labelled as Babocks triangle. It is deficient in the monocyte macrophage system, which causes hip infection.

Stages of TB Hip-Babocks Traingle

• Commonest site of TB Hip is acetabulum
• Synovitis-FABER
• Early arthritis< 1cm shortening +FADIR
• Late arthritis> 1cm shortening + FADIR
• Wandering acetabulum
• Fibrous ankylosis

TB of KNEE

There is gradual pain because Tb is chronic infection and also there is limp and flexion

Triple deformity

Tuberculosis in the initial stage will have limp and pain but if left untreated, it will develop a triple deformity

• Posterior subluxation of Tibia
• External rotation of leg
• Flexion of knee

We hope this article has helped you understand the Tuberculosis of Bone & Joints in detail. For more such information, download the PrepLadder app and study with Dream Team Next Edition (India’s top Medical facutly).