Psoriatic arthritis of the knee

Knee anatomy and what happens with psoriatic arthritis

The knee joint connects the femur and tibia bones, with the kneecap as a sliding sesamoid bone. Stabilize ligaments, menisci and the strong capsule. The crucial structures in psoriatic arthritis are the joint mucosa (synovium) and the entheses – the attachment points of tendons and ligaments to the bone.

In psoriatic arthritis, the synovium becomes inflamed (synovitis) and produces increased fluid; the knee appears swollen and overheated. At the same time, inflammation of the entheses can occur, e.g. B. at the quadriceps tendon or patellar tendon insertion. In the long term, there is a risk of cartilage damage, capsular ligament loosening and, in severe cases, bony remodeling.

• Synovitis: inflamed joint mucosa with effusion
• Enthesitis: painful inflammation of the attachment (e.g. patellar tendon)
• Irritation of menisci and ligaments due to inflammation
• Muscle imbalance due to protective posture (especially quadriceps weakness)

What is Psoriatic Arthritis of the Knee?

Psoriatic arthritis is an autoimmune disease from the spondyloarthritis group. It can occur after, parallel to or, more rarely, before skin psoriasis. The knee is one of the most commonly affected large joints. The course is individual: from symptoms that occur in fits and starts to chronic, active inflammation.

It is typical that other structures can be involved in addition to the knee: finger or toe joints (dactylitis “sausage fingers/toes”), Achilles tendon, plantar fascia and nail changes. The infestation can be unilateral or bilateral.

Symptoms and course

• Pain in the knee, often independent of stress and even at rest
• Swelling/effusion with a feeling of tension, overheating and redness
• Morning stiffness (>30 minutes), start-up pain
• Restriction of movement, limping, loss of strength
• Pressure pain at the tendon base (e.g. below/above the kneecap)
• Accompanying: skin psoriasis, nail changes, dactylitis, back pain

Flare-ups can be caused by infections, stress or mechanical overload. Untreated inflammation increases the risk of structural damage. Early anti-inflammatory action can improve the prognosis.

Causes and risk factors

Psoriatic arthritis occurs due to miscontrolled immune reactions. Genetic factors (including HLA variants) increase susceptibility. Environmental and lifestyle factors can trigger inflammation without being the sole cause.

• Genetics: familial accumulation, associations with HLA-B27, etc.
• Immunological dysregulation with synovial and entheseal inflammation
• Mechanical triggers: microtrauma, excess weight, incorrect loading
• System factors: metabolic syndrome, smoking
• Skin involvement: The extent of psoriasis partly correlates with joint risk

Differential diagnoses for an inflamed knee

A painfully swollen knee has various possible causes. A careful assessment prevents misdiagnosis and unnecessary therapy.

• Rheumatoid arthritis of the knee
• Gout or pseudogout (CPPD)
• Septic arthritis (joint infection – emergency)
• Knee osteoarthritis (with activated inflammation)
• Reactive arthritis after infections
• Meniscus or ligament injuries, bone marrow edema

If there is fever, severe redness and severe pain, an infection must be ruled out quickly - time counts here.

Diagnostics: step by step

In practice, we rely on structured, guideline-based diagnostics. Ultrasound-assisted punctures increase safety and significance.

Conservative therapy: basis of treatment

The aim is to control inflammation, relieve pain, maintain mobility and prevent subsequent damage. The therapy is put together individually, depending on activity, comorbidities and everyday needs.

• Education and joint protection: load-adapted activity, break management, use of aids.
• Physiotherapy: mobilization, stretching, strength-building exercises (quadriceps/hips), proprioceptive training.
• Ergonomics and everyday life: climbing stairs, changing between sitting and standing, techniques that are gentle on the joints at work.
• Cold therapy for acute inflammation; Warmth rather in cases of stiffness outside of the acute episode.
• Medication: NSAID/COX-2 inhibitors for a limited time and taking risks into account (stomach, kidney, heart). No parallel NSAID double.
• PPI gastric protection as required, individual benefit-risk assessment.
• Weight management and exercise (cycling, swimming, aqua jogging), quitting smoking.
• Bandages/Orthoses: temporary for relief and proprioception.

Conservative measures are regularly reviewed and adjusted. If activity continues despite basic measures, we examine joint and systemic options.

Near-joint and intra-articular measures

• Joint puncture and effusion relief: reduces pressure pain and allows diagnostics.
• Corticosteroid injection (ultrasound-guided): can locally attenuate an attack; Limit frequency and dose.
• Infiltration close to the entheses: in selected cases, careful indication.
• Hyaluronic acid: can relieve symptoms of accompanying knee osteoarthritis; with primary inflammatory activity the effect is limited.
• PRP (platelet-rich plasma): evidence for PsA of the knee is limited; Use only after detailed information and when conservative standard measures have been exhausted.

Injections do not replace systemic inflammation control in generalized PsA. They are building blocks to control local complaints.

Systemic therapy: collaboration with rheumatology

If disease activity persists or multi-joint involvement occurs, disease-modifying therapy (DMARD) is useful. This is usually done by a rheumatologist; We coordinate the local knee treatment and coordinate with each other.

• Conventional DMARDs: methotrexate, leflunomide, sulfasalazine.
• Biologics: TNF-α, IL-17 or IL-23 inhibitors, among others.
• Targeted synthetic DMARDs: JAK inhibitors.
• Consider skin involvement: close collaboration with dermatology.
• Monitoring: Laboratory and infection controls, check vaccination status (killed vaccines preferably under immunosuppressive therapy).

The selection depends on the clinical picture, comorbidities and patient preferences. A regular follow-up assessment (treat-to-target) supports control of the inflammation.

When does an operation make sense?

Surgery is not the first priority for psoriatic arthritis. The aim is to achieve good control if possible through conservative and systemic measures. Surgical procedures are considered if structural damage and relevant functional limitations persist despite therapy.

• Arthroscopic synovectomy: in selected cases for treatment-resistant local synovitis.
• Corrective procedures for misalignments only after careful examination of the indications.
• Knee endoprosthesis for advanced destruction and functional limitation.

Operational planning is carried out on an interdisciplinary basis. Immunosuppressants may need to be adjusted perioperatively; this will be coordinated with rheumatology.

Living with psoriatic arthritis: everyday life and training

• Exercise in doses but regularly: endurance sports that are gentle on the joints (cycling, swimming, cross trainer) are ideal.
• Strength training 2-3 times/week, focusing on quadriceps, hips and core; Adjust intensity to inflammatory status.
• During thrust: reduce load, cool, elevate; build mobility and strength outside of the push.
• Diet: Mediterranean-oriented can have a beneficial effect on inflammatory processes; Losing weight relieves pressure on the knee.
• Occupation/ergonomics: height-adjustable workplace, alternate sitting and standing activities, avoid stairs if the knee is acutely irritated.
• Mental health: stress management, sleep, support with pain or physical therapy programs if necessary.

Individual resilience varies. Structured activity planning that is adapted to the course of events helps to avoid setbacks.

Warning signs: when to clarify quickly?

• Acute, extremely painful, hot, red knee with fever: suspected infection - seek medical advice immediately.
• Severe pain at rest at night, pronounced restriction of movement despite rest.
• Newly occurring mechanical blockages after trauma (e.g. laceration).
• Pronounced swelling with skin tension, numbness or a feeling of paralysis.

Your orthopedic contact point in Hamburg

We offer a structured assessment and conservative treatment of psoriatic arthritis of the knee - from ultrasound to targeted punctures/injections to training and everyday life planning. When it comes to systemic therapy, we work closely with rheumatology and dermatology.

Location: Dorotheenstraße 48, 22301 Hamburg. Arrange your appointment easily online or by email. We take the time to answer your questions and work with you to create a realistic, everyday plan.