The patient exhibits a positive Trendelenburg sign, indicating weakness in the gluteus medius and minimus muscles responsible for hip abduction and pelvic stabilization. This is likely due to injury to the superior gluteal nerve. In contrast, injuries to the inferior gluteal nerve affect the gluteus maximus muscle and result in difficulty rising from a seated position or climbing stairs. The femoral nerve is responsible for knee extension and does not play a role in hip abduction. The lateral cutaneous nerve of the thigh causes pain in the posterolateral aspect of the thigh but does not cause motor impairment, while the obturator nerve controls thigh adduction and does not cause a positive Trendelenburg sign.

Lower limb anatomy is an important topic that often appears in examinations. One aspect of this topic is the nerves that control motor and sensory functions in the lower limb. The femoral nerve controls knee extension and thigh flexion, and provides sensation to the anterior and medial aspect of the thigh and lower leg. It is commonly injured in cases of hip and pelvic fractures, as well as stab or gunshot wounds. The obturator nerve controls thigh adduction and provides sensation to the medial thigh. It can be injured in cases of anterior hip dislocation. The lateral cutaneous nerve of the thigh provides sensory function to the lateral and posterior surfaces of the thigh, and can be compressed near the ASIS, resulting in a condition called meralgia paraesthetica. The tibial nerve controls foot plantarflexion and inversion, and provides sensation to the sole of the foot. It is not commonly injured as it is deep and well protected, but can be affected by popliteral lacerations or posterior knee dislocation. The common peroneal nerve controls foot dorsiflexion and eversion, and can be injured at the neck of the fibula, resulting in foot drop. The superior gluteal nerve controls hip abduction and can be injured in cases of misplaced intramuscular injection, hip surgery, pelvic fracture, or posterior hip dislocation. Injury to this nerve can result in a positive Trendelenburg sign. The inferior gluteal nerve controls hip extension and lateral rotation, and is generally injured in association with the sciatic nerve. Injury to this nerve can result in difficulty rising from a seated position, as well as difficulty jumping or climbing stairs.

Erysipelas is a skin infection that is localized and caused by Streptococcus pyogenes. It is often seen in elderly patients with weakened immune systems, such as those with diabetes mellitus. Symptoms include a raised, painful rash with clear boundaries.

Ringworm is commonly caused by Trichophyton rubrum. This results in a circular, scaly, and itchy rash that is red in color.

While Staphylococcus epidermidis is a normal part of the skin’s flora, it is more commonly associated with infections of foreign devices and endocarditis rather than skin infections.

Understanding Erysipelas: A Superficial Skin Infection

Erysipelas is a skin infection that is caused by Streptococcus pyogenes. It is a less severe form of cellulitis, which is a more widespread skin infection. Erysipelas is a localized infection that affects the skin’s upper layers, causing redness, swelling, and warmth. The infection can occur anywhere on the body, but it is most commonly found on the face, arms, and legs.

The treatment of choice for erysipelas is flucloxacillin, an antibiotic that is effective against Streptococcus pyogenes. Other antibiotics may also be used, depending on the severity of the infection and the patient’s medical history.

ANCA Associated Vasculitis: Types, Symptoms, and Management

ANCA associated vasculitis is a group of small-vessel vasculitides that are associated with anti-neutrophil cytoplasmic antibodies (ANCA). These include granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome), and microscopic polyangiitis. ANCA associated vasculitis is more common in older individuals and presents with symptoms such as renal impairment, respiratory symptoms, systemic symptoms, vasculitic rash, and ear, nose, and throat symptoms.

To diagnose ANCA associated vasculitis, first-line investigations include urinalysis for haematuria and proteinuria, blood tests for renal impairment, full blood count, CRP, and ANCA testing. There are two main types of ANCA – cytoplasmic (cANCA) and perinuclear (pANCA) – with cANCA being associated with granulomatosis with polyangiitis and pANCA being associated with eosinophilic granulomatosis with polyangiitis and other conditions.

Once suspected, ANCA associated vasculitis should be managed by specialist teams to allow an exact diagnosis to be made. The mainstay of management is immunosuppressive therapy. Kidney or lung biopsies may be taken to aid the diagnosis.

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.

Sharpey’s fibers, which are strong collagenous fibers, attach the periosteum to the bone and extend to the outer circumferential and interstitial lamellae. Additionally, the periosteum serves as a point of attachment for muscles and tendons.

Understanding Periosteum: The Membrane Covering Bones

Periosteum is a membrane that envelops the outer surface of all bones, except at the joints of long bones. It is made up of dense irregular connective tissue and is divided into two layers: the outer fibrous layer and the inner cambium layer. The fibrous layer contains fibroblasts, while the cambium layer contains progenitor cells that develop into osteoblasts. These osteoblasts are responsible for increasing the width of a long bone and the overall size of other bone types.

Periosteum is very sensitive to manipulation as it has nociceptive nerve endings. It also provides nourishment by supplying blood to the bone. The membrane is attached to the bone by strong collagenous fibers called Sharpey’s fibers, which extend to the outer circumferential and interstitial lamellae. Additionally, periosteum provides an attachment for muscles and tendons.

After a bone fracture, the progenitor cells develop into osteoblasts and chondroblasts, which are essential to the healing process. Periosteum that covers the outer surface of the bones of the skull is known as pericranium, except when referring to the layers of the scalp. Understanding periosteum is crucial in comprehending bone structure and the healing process after a bone fracture.

The patient has been experiencing chronic pain throughout her body for the past 6 months. Rheumatoid arthritis is unlikely as the pain does not seem to be originating from the joints. Fibromyalgia and polymyalgia rheumatica are the two most probable diagnoses, but the absence of weight loss and fever makes polymyalgia rheumatica less likely. Therefore, fibromyalgia is the most likely diagnosis. The patient also reports feeling tired and having sleep disturbances, which are common symptoms of fibromyalgia.

1: This condition primarily affects individuals over 50 years old and is associated with elevated levels of inflammatory markers like ESR and CRP. It is linked to giant cell arteritis, but serum CK and muscle biopsy results are normal.
2: Fibromyalgia is characterized by widespread musculoskeletal pain and tenderness in various points of the body.
3: The patient has not reported any muscle weakness. If weakness in the shoulder region was present, polymyositis would be a more probable diagnosis.
4: This inflammatory musculoskeletal condition primarily affects the axial skeleton and is strongly associated with the HLA-B27 histocompatibility complex. The initial symptom is typically lower back pain due to sacroiliitis.
5:

Fibromyalgia is a condition that causes widespread pain throughout the body, along with tender points at specific anatomical sites. It is more common in women and typically presents between the ages of 30 and 50. Other symptoms include lethargy, cognitive impairment (known as fibro fog), sleep disturbance, headaches, and dizziness. Diagnosis is made through clinical evaluation and the presence of tender points. Management of fibromyalgia is challenging and requires an individualized, multidisciplinary approach. Aerobic exercise is the most effective treatment, along with cognitive behavioral therapy and medication such as pregabalin, duloxetine, and amitriptyline. However, there is a lack of evidence and guidelines to guide treatment.

Understanding Tumour Necrosis Factor and its Inhibitors

Tumour necrosis factor (TNF) is a cytokine that plays a crucial role in the immune system. It is mainly secreted by macrophages and has various effects on the immune system, such as activating macrophages and neutrophils, acting as a costimulator for T cell activation, and mediating the body’s response to Gram-negative septicaemia. TNF also has anti-tumour effects and binds to both the p55 and p75 receptor, inducing apoptosis and activating NFkB.

TNF has endothelial effects, including increased expression of selectins and production of platelet activating factor, IL-1, and prostaglandins. It also promotes the proliferation of fibroblasts and their production of protease and collagenase. TNF inhibitors are used to treat inflammatory conditions such as rheumatoid arthritis and Crohn’s disease. Examples of TNF inhibitors include infliximab, etanercept, adalimumab, and golimumab.

Infliximab is also used to treat active Crohn’s disease unresponsive to steroids. However, TNF blockers can have adverse effects such as reactivation of latent tuberculosis and demyelination. Understanding TNF and its inhibitors is crucial in the treatment of various inflammatory conditions.

The ulna serves as the insertion point for the brachialis muscle, while the remaining muscles are inserted onto the radius.

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.

The function of flexor digitorum profundus is to flex the fingers at both interphalangeal joints and the metacarpophalangeal joints, with a specific responsibility for flexing the distal interphalangeal joint. In contrast, flexor digitorum superficialis only flexes the metacarpophalangeal and proximal interphalangeal joints of the fingers, and must be isolated from the action of flexor digitorum profundus to assess its function. Flexor hallucis longus, on the other hand, flexes the joints of the great toe but not the distal interphalangeal joints.

The forearm flexor muscles include the flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum superficialis, and flexor digitorum profundus. These muscles originate from the common flexor origin and surrounding fascia, and are innervated by the median and ulnar nerves. Their actions include flexion and abduction of the carpus, wrist flexion, adduction of the carpus, and flexion of the metacarpophalangeal and interphalangeal joints.

The patient has both osteoarthritis and rheumatoid arthritis, with the latter affecting the smaller joints of the hands and feet. Methotrexate is a commonly used immunosuppressive medication for rheumatoid arthritis, but it can cause hepatotoxicity as a significant side effect.

Although fat emboli are a potential risk after orthopaedic surgery, they usually cause neural and respiratory symptoms rather than liver damage. Additionally, the onset of fat emboli occurs within hours to days after the operation, not three months later.

While calcium channel blockers, ACE inhibitors, and opioid medications have their own side effects, they typically do not affect liver function.

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.