The most probable diagnosis for this patient is pseudogout, which is characterized by the deposition of calcium pyrophosphate dihydrate crystals in the synovium, resulting in pain during movement. The knee joint is commonly affected, and the presence of rhomboid-shaped crystals that are positively birefringent in polarised-light microscopy of joint aspirate confirms the diagnosis. Radiography may also reveal chondrocalcinosis.

A fracture would require a history of trauma and would be visible on the radiograph, neither of which is present in this case, making it an unlikely diagnosis.

Reactive arthritis is associated with immune-mediated destruction of the joint, but there is no recent history of diarrhoea, coryza, conjunctivitis, or urethritis, which are commonly associated with this condition. The light microscopy of joint aspirate and radiography findings do not support this diagnosis.

Joint infection typically presents with a hot, swollen joint that rapidly develops after a history of trauma. The joint aspirate would be expected to contain turbid fluid and grow organisms. However, none of these features are present in this patient, making joint infection an unlikely diagnosis.

Understanding Pseudogout

Pseudogout, also known as acute calcium pyrophosphate crystal deposition disease, is a type of microcrystal synovitis that occurs when calcium pyrophosphate dihydrate crystals are deposited in the synovium. This condition is commonly associated with increasing age, but younger patients who develop pseudogout usually have an underlying risk factor such as haemochromatosis, hyperparathyroidism, low magnesium or phosphate levels, acromegaly, or Wilson’s disease.

The knee, wrist, and shoulders are the most commonly affected joints in pseudogout. Diagnosis is made through joint aspiration, which reveals weakly-positively birefringent rhomboid-shaped crystals, and x-rays, which show chondrocalcinosis. In the knee, linear calcifications of the meniscus and articular cartilage can be seen.

Management of pseudogout involves joint fluid aspiration to rule out septic arthritis, followed by treatment with NSAIDs or intra-articular, intra-muscular, or oral steroids, similar to the treatment for gout. Understanding the risk factors and symptoms of pseudogout can help with early diagnosis and effective management of this condition.

The knee joint is the largest and most complex synovial joint in the body, consisting of two condylar joints between the femur and tibia and a sellar joint between the patella and femur. The degree of congruence between the tibiofemoral articular surfaces is improved by the presence of the menisci, which compensate for the incongruence of the femoral and tibial condyles. The knee joint is divided into two compartments: the tibiofemoral and patellofemoral compartments. The fibrous capsule of the knee joint is a composite structure with contributions from adjacent tendons, and it contains several bursae and ligaments that provide stability to the joint. The knee joint is supplied by the femoral, tibial, and common peroneal divisions of the sciatic nerve and by a branch from the obturator nerve, while its blood supply comes from the genicular branches of the femoral artery, popliteal, and anterior tibial arteries.

Azathioprine is an immunosuppressant that is commonly used to maintain remission in Crohn’s disease. It is metabolized into mercaptopurine, which inhibits purine synthesis and helps to control inflammation.

Infliximab is a monoclonal antibody that is sometimes used to induce remission in refractory or fistulating Crohn’s disease. It works by binding to and neutralizing tumor necrosis factor, a key mediator of inflammation.

Mesalazine is a second-line drug that is used to induce remission in Crohn’s disease after glucocorticoids. It belongs to the 5-aminosalicylate class of drugs and works by inhibiting prostaglandin secretion. It is also considered for use in maintaining remission in post-surgical Crohn’s patients.

Methotrexate is another immunosuppressant that is used as a second-line treatment for Crohn’s disease. It works by disrupting folic acid metabolism and accumulating the anti-inflammatory molecule adenosine.

Metronidazole is an antibiotic that is used to treat isolated peri-anal Crohn’s disease. It works by forming radicals that disrupt the DNA of anaerobic bacteria.

Azathioprine is a medication that is converted into mercaptopurine, which is an active compound that inhibits the production of purine. To determine if someone is at risk for azathioprine toxicity, a test for thiopurine methyltransferase (TPMT) may be necessary. Adverse effects of this medication include bone marrow depression, nausea and vomiting, pancreatitis, and an increased risk of non-melanoma skin cancer. If infection or bleeding occurs, a full blood count should be considered. It is important to note that there may be a significant interaction between azathioprine and allopurinol, so lower doses of azathioprine should be used. However, azathioprine is generally considered safe to use during pregnancy.

Although ruptures of the biceps muscle near its origin are more common, injuries to the distal portion of the muscle, where it attaches to the radial tuberosity, are less frequent but more significant from a clinical standpoint.

Anatomy of the Radius Bone

The radius bone is one of the two long bones in the forearm that extends from the lateral side of the elbow to the thumb side of the wrist. It has two expanded ends, with the distal end being the larger one. The upper end of the radius bone has articular cartilage that covers the medial to lateral side and articulates with the radial notch of the ulna by the annular ligament. The biceps brachii muscle attaches to the tuberosity of the upper end.

The shaft of the radius bone has several muscle attachments. The upper third of the body has the supinator, flexor digitorum superficialis, and flexor pollicis longus muscles. The middle third of the body has the pronator teres muscle, while the lower quarter of the body has the pronator quadratus muscle and the tendon of supinator longus.

The lower end of the radius bone is quadrilateral in shape. The anterior surface is covered by the capsule of the wrist joint, while the medial surface has the head of the ulna. The lateral surface ends in the styloid process, and the posterior surface has three grooves that contain the tendons of extensor carpi radialis longus and brevis, extensor pollicis longus, and extensor indicis. Understanding the anatomy of the radius bone is crucial in diagnosing and treating injuries and conditions that affect this bone.

Wharton’s duct is encircled by the lingual nerve, which is responsible for providing sensory innervation to the front two-thirds of the tongue.

Anatomy of the Submandibular Gland

The submandibular gland is located beneath the mandible and is surrounded by the superficial platysma, deep fascia, and mandible. It is also in close proximity to various structures such as the submandibular lymph nodes, facial vein, marginal mandibular nerve, cervical branch of the facial nerve, deep facial artery, mylohyoid muscle, hyoglossus muscle, lingual nerve, submandibular ganglion, and hypoglossal nerve.

The submandibular duct, also known as Wharton’s duct, is responsible for draining saliva from the gland. It opens laterally to the lingual frenulum on the anterior floor of the mouth and is approximately 5 cm in length. The lingual nerve wraps around the duct, and as it passes forward, it crosses medial to the nerve to lie above it before crossing back, lateral to it, to reach a position below the nerve.

The submandibular gland receives sympathetic innervation from the superior cervical ganglion and parasympathetic innervation from the submandibular ganglion via the lingual nerve. Its arterial supply comes from a branch of the facial artery, which passes through the gland to groove its deep surface before emerging onto the face by passing between the gland and the mandible. The anterior facial vein provides venous drainage, and the gland’s lymphatic drainage goes to the deep cervical and jugular chains of nodes.

The patient’s blood test indicates a decrease in red blood cells, white blood cells, and platelets, which is known as pancytopenia. This condition is caused by severe bone marrow suppression, which is a common side effect of methotrexate. Anemia, on the other hand, would only result in a low hemoglobin level and cannot account for the low platelet and white blood cell counts.

Methotrexate is an antimetabolite that hinders the activity of dihydrofolate reductase, an enzyme that is crucial for the synthesis of purines and pyrimidines. It is a significant drug that can effectively control diseases, but its side-effects can be life-threatening. Therefore, careful prescribing and close monitoring are essential. Methotrexate is commonly used to treat inflammatory arthritis, especially rheumatoid arthritis, psoriasis, and acute lymphoblastic leukaemia. However, it can cause adverse effects such as mucositis, myelosuppression, pneumonitis, pulmonary fibrosis, and liver fibrosis.

Women should avoid pregnancy for at least six months after stopping methotrexate treatment, and men using methotrexate should use effective contraception for at least six months after treatment. Prescribing methotrexate requires familiarity with guidelines relating to its use. It is taken weekly, and FBC, U&E, and LFTs need to be regularly monitored. Folic acid 5 mg once weekly should be co-prescribed, taken more than 24 hours after methotrexate dose. The starting dose of methotrexate is 7.5 mg weekly, and only one strength of methotrexate tablet should be prescribed.

It is important to avoid prescribing trimethoprim or co-trimoxazole concurrently as it increases the risk of marrow aplasia. High-dose aspirin also increases the risk of methotrexate toxicity due to reduced excretion. In case of methotrexate toxicity, the treatment of choice is folinic acid. Overall, methotrexate is a potent drug that requires careful prescribing and monitoring to ensure its effectiveness and safety.

The most common cause of osteomyelitis is Staphylococcus aureus, a bacteria that is normally found on the skin and mucus membranes but can become pathogenic in individuals who are immunocompromised or have risk factors for infections. Clostridium perfringens, Pseudomonas aeruginosa, and Staphylococcus epidermidis are not common causes of osteomyelitis, although they may cause other types of infections.

Understanding Osteomyelitis: Types, Causes, and Treatment

Osteomyelitis is a bone infection that can be classified into two types: haematogenous and non-haematogenous. Haematogenous osteomyelitis is caused by bacteria in the bloodstream and is usually monomicrobial. It is more common in children and can be caused by risk factors such as sickle cell anaemia, intravenous drug use, immunosuppression, and infective endocarditis. On the other hand, non-haematogenous osteomyelitis is caused by the spread of infection from adjacent soft tissues or direct injury to the bone. It is often polymicrobial and more common in adults, with risk factors such as diabetic foot ulcers, pressure sores, diabetes mellitus, and peripheral arterial disease.

Staphylococcus aureus is the most common cause of osteomyelitis, except in patients with sickle-cell anaemia where Salmonella species are more prevalent. To diagnose osteomyelitis, MRI is the imaging modality of choice, with a sensitivity of 90-100%.

The treatment for osteomyelitis involves a course of antibiotics for six weeks. Flucloxacillin is the preferred antibiotic, but clindamycin can be used for patients who are allergic to penicillin. Understanding the types, causes, and treatment of osteomyelitis is crucial in managing this bone infection.

Psoriasis is caused by type 1 helper T cells that participate in the cellular immune response, as opposed to type 2 helper T cells.

Psoriasis: A Chronic Skin Disorder with Various Subtypes and Complications

Psoriasis is a prevalent chronic skin disorder that affects around 2% of the population. It is characterized by red, scaly patches on the skin, but it is now known that patients with psoriasis are at an increased risk of arthritis and cardiovascular disease. The pathophysiology of psoriasis is multifactorial and not yet fully understood. It is associated with genetic factors such as HLA-B13, -B17, and -Cw6, and abnormal T cell activity that stimulates keratinocyte proliferation. Environmental factors such as skin trauma, stress, streptococcal infection, and sunlight exposure can worsen, trigger, or improve psoriasis.

There are several recognized subtypes of psoriasis, including plaque psoriasis, flexural psoriasis, guttate psoriasis, and pustular psoriasis. Each subtype has its own unique characteristics and affects different areas of the body. Psoriasis can also cause nail signs such as pitting and onycholysis, as well as arthritis.

Complications of psoriasis include psoriatic arthropathy, metabolic syndrome, cardiovascular disease, venous thromboembolism, and psychological distress. It is important for patients with psoriasis to receive proper management and treatment to prevent these complications and improve their quality of life.

Azathioprine is known to cause pancreatitis, which is likely the adverse effect experienced by this patient. It is possible that the patient was prescribed azathioprine after presenting with severe bloody diarrhea, a symptom of an acute flare-up of ulcerative colitis. Other drugs listed are not commonly associated with pancreatitis, although erythromycin may have a weak association. For more information on serious adverse effects of the listed drugs, please refer to the table below.

Drug Serious adverse effects
Paracetamol Hepatotoxicity
Amitriptyline Anticholinergic side effects
Erythromycin GI disturbance and prolongs QT interval
Azathioprine Bone marrow depression and pancreatitis

Azathioprine is a medication that is converted into mercaptopurine, which is an active compound that inhibits the production of purine. To determine if someone is at risk for azathioprine toxicity, a test for thiopurine methyltransferase (TPMT) may be necessary. Adverse effects of this medication include bone marrow depression, nausea and vomiting, pancreatitis, and an increased risk of non-melanoma skin cancer. If infection or bleeding occurs, a full blood count should be considered. It is important to note that there may be a significant interaction between azathioprine and allopurinol, so lower doses of azathioprine should be used. However, azathioprine is generally considered safe to use during pregnancy.

The deep peroneal nerve innervates all the muscles in the anterior compartment, including the Tibialis anterior, Extensor digitorum longus, Peroneus tertius, and Extensor hallucis longus. Additionally, the Anterior tibial artery is also located in this compartment.

Muscular Compartments of the Lower Limb

The lower limb is composed of different muscular compartments that perform various actions. The anterior compartment includes the tibialis anterior, extensor digitorum longus, peroneus tertius, and extensor hallucis longus muscles. These muscles are innervated by the deep peroneal nerve and are responsible for dorsiflexing the ankle joint, inverting and evert the foot, and extending the toes.

The peroneal compartment, on the other hand, consists of the peroneus longus and peroneus brevis muscles, which are innervated by the superficial peroneal nerve. These muscles are responsible for eversion of the foot and plantar flexion of the ankle joint.

The superficial posterior compartment includes the gastrocnemius and soleus muscles, which are innervated by the tibial nerve. These muscles are responsible for plantar flexion of the foot and may also flex the knee.

Lastly, the deep posterior compartment includes the flexor digitorum longus, flexor hallucis longus, and tibialis posterior muscles, which are innervated by the tibial nerve. These muscles are responsible for flexing the toes, flexing the great toe, and plantar flexion and inversion of the foot, respectively.

Understanding the muscular compartments of the lower limb is important in diagnosing and treating injuries and conditions that affect these muscles. Proper identification and management of these conditions can help improve mobility and function of the lower limb.