Septic Arthritis & Osteomyelitis PDF

# Syptic Arthritis - It is an inflammation of joints secondary to **infectious etiology**. - May affect any joint, but the most common joints are: - Knee (50%) - Hip - Shoulder ## Risk factors: 1. Old age 2. Diabetes 3. RA 4. Liver cirrhosis 5. HIV ## Pathophysiology:...

# Syptic Arthritis - It is an inflammation of joints secondary to **infectious etiology**. - May affect any joint, but the most common joints are: - Knee (50%) - Hip - Shoulder ## Risk factors: 1. Old age 2. Diabetes 3. RA 4. Liver cirrhosis 5. HIV ## Pathophysiology: - It is mainly due to bacterial seeding of the joint ## Etiology: - There are 3 causes of this bacterial seeding of joint 1. Bacteraemia or hematogenous spread (It is the most common cause on children) 2. Direct infection. (Due to trauma or surgery) 3. Contagious spread (spread of infection on the bone medulla) - Whatever was the cause, when the bacteria reach the joint, it starts releasing "**proteolytic enzymes**", which in turn causes **articular cartilage destruction**. - The most common organism or pathogene is "**staph aureus**". - It is already a complication ## The criteria & presentation: - Joint pain. (It isn't relieved by analgesics). (It isn't provoked by activity "**Persistent pain**") - Toxic appearance. - Fever is not common - Erythema - Joint effusion - Tender joint line - Restricted ROM - Inability to bear weight. - I can't depend on the inflammation criteria as it could be any other problem that causes the inflammation. - So instead, depend on **investigations**. ## Investigations: - X-ray & MRI are not sensitive. - Musculoskeletal US could be useful. ### BUT - The gold standard is: - "Sample aspiration culture" - "Aspiration biopsy" - After collecting the sample, it should **followed by "Culture sensitivity"** to define the organism and start the proper treatment. - Sometimes we use the previous but with US or CT, which is called "guided aspiration biopsy". - You will find "**sinus discharging pus**" which is the gold standard finding that can 100% insure that it is infection. ## Lab examination: - ESR > 30 mm/h (more accurate) - CRP > 10 mg/dl - CBC > Leukocytosis, shifted to the left. - Joint aspiration will show: - WBC > 50000 - ↑ macrophages & inflammatory markers. ## Treatment: - **Drainage**. - Arthroscopic arthrotomy. (**Knee**) - Open arthrotomy (**Hip**, as it is a deep joint) - Arthrotomy = debridment & lavage. - **Antibiotic**. - IV or injection. (**For 2 weeks at least**) - Followed by oral (**For 4 weeks**) - ESR & CRP are made later for follow up. ## Complications: 1. OA 2. Osteomyelitis 3. Deformity # Osteomyelitis - Infection of the bone characterized by progressive **inflammatory destruction** and apposition of new bone. ## Risk factors: 1. Trauma or post surgery. 2. Immunodeficiency disease. 3. Diabetes. 4. Smoking 5. Peripheral vascular disorders. ## Pathophysiology: - The mechanism of spread could be: 1. **Hematogenous spread**. (Common on children). (In adults it affects the vertebrea "axial skeleton") 2. **Contiguous spread**. 3. **Direct spread**. (Open fractures or penetrating injury) ## Two stages for the disease: - Planktonic stage. - The organism here is only attached to the bone surface, which is called "**apoptosis**". - In this stage, it is simple. If you perform a proper antibiotic treatment and aggressive debridment, you should be fine. But if the infection reaches stage II, it will be a problem. - **Biofilm formation**. - The problem with this stage is that the bacteria start creating a membrane around them, this membrane is called "biofilm". This is problematic because it resists antibiotic treatment. ## Cierny mader classification ### 1- Anatomical type: | Stage | Description | | :--------------- | :-------------------------- | | Stage I | Medullary | | Stage II | Superficial | | Stage III | Localized | | Stage IV | Diffuse | ### 2- Host type: | Type | Description | | :--------------- | :------------------------------------ | | Type A | Normal without comorbidities. | | Type B | Local or systemic compromises. | | Type C | The patient is in very bad condition. | - Type A: I know my surgery will be successful for this patient. - Type B: This patient may have mild diabetes, smokes, or is on steroids. The surgery will be successful but has lower success rates than type A. - Type C: The patient is very old, has a heart surgery, etc. This patient has uncontrolled diabetes and is considered unfit for surgery and is likely going to die on the table. These patients should not be operated on. ## Clinical presentation: - Same as it was on septic arthritis. And be careful, you may find sinus discharge pus if the case was chronic and neglected, but it still very rare. ## Examination: - Test the pain & ROM of the joint above and the joint below + Nuerovascular examination to see if there is Peripheral vascular disorders or not, and because he may be type B according to host type. ## Investigations: - X-ray. - You will find "**sequestrum - involucrum**" - **Sequestrum:** black central area of bone necrosis. - **Involucrum:** a white margin of bone sclerosis. - The sequestrum is black because it represents the infection nest and is surrounded by a white rim of new bone that the body tries to form to repair it. This is called the **involucrum**. - This shows up on X-ray but only after 6 weeks after the beginning of **chronic osteomyelitis** but not acute cases. - CT. - MRI. - **Gallium bone scan**. - It is a radioactive element that is very sensitive to any site of infection, and when it is absorbed by the organisms, it appears like a black hole on the image called a "**Hot spot**". - However, this is not a very accurate test because it may detect a tumor, and not an infection. - **Lab examination:** - ESR > 30 mm/h (more accurate) - CRP > 10 mg/dl - CBC > Leukocytosis, shifted to the left - But all the previous are still not accurate because my gold standard in diagnosis of **osteomyelitis** is "**Bone culture**." - I use a bone marrow needle to take a small sample, and then perform a culture sensitivity. ## Differential diagnosis: - Tumour, fracture healing. - So, biopsy and culture is the key. ## Treatment: ### Surgical treatment - Aggressive radical debridment & irrigation (lavage) by 9L saline then fixate with plate and screw if the case was stable. - But if the metal implants were loose or unstable, it means that the infection is not completely eliminated. - The metal implant should be removed, and external fixators should be used till the infection is fully eliminated. - After 6 weeks, a second surgery should be performed by fixing the bone with an intramedullary nail and manage the dead space by bone cement for 6 weeks followed by bone graft. ### Antibiotics - For 6 weeks, divided into: - 2 weeks IV antibiotics - 4 weeks oral antibiotics