Hip joint septic arthritis causing hip pain is a purulent joint disorder known as suppurative arthritis of the hip joint. Bacteria, virus or fungus causes joint infection. Joint infection causes tissue destruction resulting in pus or purulent secretions within the joint consist of dead cells, tissue debris and synovial fluid mixed with bacteria and blood cells.
Causes of Hip Joint Septic Arthritis
- Bacterial Infection of Hip Joint– Most common cause of septic arthritis.
- Staphylococcus Aureus– Seen more often in young adult.
- Hemophilus Influenza– Often seen in children.
- Streptococci– Most common cause of bacterial arthritis in all age groups.
- Neisseria Gonorrhea– Seen in young adult.
- Escherichia Coli– Seen in elderly debilitating patients, IV drug users and seriously ill patients.
- Pseudomonas Aeruginosa– Observed in children following penetrating wound close to knee joint.
- Systemic Infection Of Hip Joint
- Bacteremia– Bacterial or viral infection of soft tissue and organs like lungs, kidney and intestine spreads into blood. Bacteria are carried by blood to distant organ and infiltrate into tissue from capillary circulation.
- Abscess of Distant Organ– Abscess often infiltrate into blood stream from rupture capillary wall and spreads as tiny drops (emboli) to distant organs and joints. Joint spread of abscess emboli may affect single or multiple joints.
- Spread of Infection To Adjacent Tissue Causing Severe Hip Pain
- Adjacent Wound Infection– Trauma or fall causes skin laceration, muscle tears or fracture of the extremity bones. Infection of skin laceration over hip joint may cause abscess within subcutaneous tissue and muscles. Abscess may spread into hip joint resulting in septic arthritis of hip joint causing severe intractable hip pain.
- Osteomyelitis– Osteomyelitis is an infection of bone. Infection caused by Osteomyelitis of adjacent femur or pelvis may spread to hip joint causing hip pain.
- Adjacent Soft Tissue Infection– Soft tissue infection around hip joint like dermatitis, carbuncle, tendinitis and subcutaneous abscess may spread into hip joint resulting in moderate to severe hip pain in addition to soft tissue pain.
- Hip Joint Pain and Infection Associated With Prosthesis-
- Hip Pain and Infection Following Hip Joint Prosthetic Surgery-Total or partial hip joint replacement involves metal prosthesis. Prosthesis is treated as a foreign body by a healthy surrounding tissue. Hip Pain and Infection associated with prosthetic hip joint is extremely difficult to treat with antibiotics. Lack of blood vessels within and around the prosthesis results in low white blood cells count and also prevents antibiotics coming in contact with bacteria. Low white blood cell count is unable to prevent bacterial rapid multiplications. Often prosthesis has to be removed to treat infection with antibiotics. Revision of total hip joint replacement is considered once all the studies including study of joint fluid indicates the joint is germ-free and disinfected.
- Penetrating Trauma Resulting in Hip Joint Septic Arthritis
- Depth of penetrating wound could be superficial or deep. Deep penetrating wound over hip joint if not treated appropriately results in abscess formation. Deep tissue abscess close to joint may spread within the joint causing septic arthritis and severe hip pain.
- Pre-Existing Inflammatory Hip Joint Disease
- Inflammatory Joint Disease– Inflammatory joint diseases like osteoarthritis, gout, rheumatoid arthritis and lupus may promote infection in immune suppressed patients. Septic arthritis associated with inflammatory hip joint disease results in intense hip pain which is often difficult to treat.
- Weak Immune System Resulting in Septic Hip Joint Arthritis
- Anti-inflammatory Medications such as NSAIDs and corticosteroid causes decreased soft tissue immunity surrounding the joint. Such condition often promotes bacterial, viral or fungal infection. Hip pain is often resistant to opioids and NSAIDS.
- Immunosuppressant– Immunosuppressant medications are often prescribed to treat rheumatoid arthritis and psoriatic arthritis. Infection of inflammatory joint is common when treated with immunosuppressant.
- Skin Infection
- Psoriasis-Infected psoriatic skin lesion may be a source of bacteria. Patient is often treated with anti inflammatory or immunosuppressant medication resulting in reduced immunity against infection. Bacterial infection may spread through blood from skin and cause hip joint infection. Hip Pain is often severe in psoariatic arthritis. Hip Pain becomes difficult to treat when caused by septic psoariatic arthritis.
Symptoms and Signs of Septic Arthritis of Hip Joint
Symptoms of Hip Joint Septic Arthritis
Septic purulent hip arthritis is a Medical Emergency and patient should be treated with appropriate antibiotics as soon as possible.
- Hip Pain– Is severe, intensity of pain changes from mild to severe rapidly.
- Loss of Appetite– Infection follows loss of appetite and loss of weight.
- Fatigue– Patient feels weak and activities become restricted.
- Generalized Weakness– Weakness observed secondary to loss of appetite, fatigue and fever.
- Monoarthritis– Joint infection is often unilateral, bilateral septic arthritis is very rare.
Signs of Hip Joint Septic Arthritis
- Hip Joint Swelling– Fluctuating swelling is observed over the hip joint secondary to pus and synovial fluid in the joint causing separation of head of the femur from sockets. Consistency is soft.
- Redness Over Hip Joint Skin over the hip joint is red indicating sign of inflammation.
- Warmth– Skin is warm to touch, redness and warm joint indicates signs of inflammation and purulent secretion in the joint.
- Joint Movements– Movements are restricted and any movement triggers severe pain.
- Fever– Over 38.5 C or 101.3 F.
- Joint Damage– Septic hip joint arthritis often damages cartilage, tendon, joint ligament and surface of the bone underneath cartilage.
Diagnosis and Investigations for Hip Joint Septic Arthritis
Diagnoses of Hip Joint Septic Arthritis
- Unilateral Hip Joint Pain
- Skin over Infected Hip Joint- Warm and Red.
Investigation For Hip Joint Septic Arthritis
Specific Test for Septic Arthritis of Hips
- WBC– White blood cell count is high.
- ESR- Erythrocyte sedimentation rate (ESR) is increased during active inflammation as well as infection is presented as septic hip joint disease. ESR is specific test used to observe the prognosis of the disease during active treatment with antibiotics. Otherwise ESR is also elevated in Rheumatoid Arthritis, Osteoarthritis and Psoriatic Arthritis.
Tests to Rule Out Other Diseases Causing Hip Joint Pain
- Rheumatoid Factors (RF)– RF is a protein molecule known as antibodies. Blood examination of 70% to 90% of patients suffering with rheumatoid arthritis. Test is performed to rule out rheumatoid arthritis.
- Serum Cytokines– Cytokines and related protein factors are elevated in early stages of rheumatoid disease. Cytokine factors are used as a marker to diagnose early stage of rheumatoid arthritis.
- HLA-B27 Genetic Marker– Test is performed to rule out psoriatic arthritis. Test is positive in inflammatory joint diseases like Psoriatic hip joint disease, Ankylosing Spondylitis and Reiter’s syndrome.
Joint Fluid Analysis (Arthrocentesis)-
- Aspiration Test– Joint fluid is aspirated under aseptic condition and tested for infections. Test involves-
- Bacterial Culture.
- Antibiotic Sensitivity Test– Bacterial cultures are treated with several antibiotics to evaluate which antibiotic is most effective to treat infection.
- Evaluate the white blood cell count in purulent discharge aspirated from septic arthritis. White blood cell count is significantly increased in Septic Arthritis.
- Ultrasound Test- May reveal joint effusion.
- X-Ray-Findings are as follows-
- Joint effusion and joint space may be filled with pus and synovial fluid.
- Joint space is wide.
- MRI-Findings are as follows-
- Uneven cartilage linings and joint surface is observed in later stages.
- Joint space is filled with pus or synovial fluid.
- Joint subluxation may be observed in long standing advanced disease.
- Synovial membrane thickening and perisynovial edema are seen.
- Bone marrow abnormalities may be observed if osteomyelitis is the caused of hip joint infection.
Treatment for Hip Joint Septic Arthritis
Conservative Treatment for Hip Joint Septic Arthritis
- Heat or Cold Therapy
- Assistive Devices for Ambulation- Cane, walker or wheelchair.
- Weight Loss.
- Exercise or Yoga Therapy
Specific Treatment for Hip Joint Septic Arthritis
- Pain Caused by Hip Joint Septic Arthritis
- NSAIDs for septic arthritis pain.
- Opioids- Is indicated if NSAIDs are not effective to relieve septic arthritis pain.
- Antidepressant Analgesics– Is indicated if NSAIDS and Opioids are not effective to treat neuropathic pain caused by hip joint septic arthritis.
- Antiepileptic Analgesics– Is alternative to antidepressant analgesics and is indicated if NSAIDS and Opioids are not effective to treat neuropathic pain caused by hip joint septic arthritis.
- Infection Causing Hip Joint Septic Arthritis
- Oral Antibiotics– Oral route is selected if infection is mild and duration of symptoms is short since the beginning of initial symptoms of pain.
- Intravenous Antibiotics– Septic hip joint arthritis is often medical emergency and intravenous antibiotic is the route of antibiotic treatment.
- Arthrocentesis and Antibiotic Injection– antibiotics are injected in the hip joint during Arthrocentesis procedure
- Inflammation Caused by Hip Joint Septic Arthritis –
- Anti-Inflammatory Medications– Hip Joint Septic Arthritis Inflammation is treated with NSAIDs like Motrin and Celebrex.
- Muscle Spasm Secondary to Hip Joint Septic Arthritis – Muscle spasm is treated with muscle relaxants. Following muscle relaxants are often used-
Physical Therapy for Hip Joint Septic Arthritis
PT is indicated for following clinical manifestations
- Muscle Spasm
- Joint Stiffness
- Joint Instability
- Abnormal Gait
Surgery to Treat Hip Joint Septic Arthritis
- Joint Aspiration and Injection of Antibiotics– Aseptic aspiration of the joint is performed under aseptic condition to remove pus and also inject antibiotics directly into the joint.
- Joint Debridement-Severe hip joint damage and destruction is treated with surgical debridement and aspiration of pus.
- Hip Joint Replacement-Head of the femur, neck of the femur and acetabulum is replaced with artificial metal prosthesis.
- Partial Hip Joint Replacement– Head of the femur or neck of the femur is replaced with artificial metal prosthesis.
- Hip Resurfacing– The surface of the head of the femur and acetabulum is replaced and covered with cobalt metal cap.
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