Rheumatological Examination of the Hands — Written Clinical Reasoning

SAQ 1 — Rheumatological Hand Examination: Diagnosis, Disease Activity, and Management Plan (20 marks, 30 minutes)

Prompt: Outline your systematic approach to this patient's hand examination, addressing: (a) the six-step examination routine and how each step contributes to the diagnosis; (b) the interpretation of the findings and the most likely diagnosis with its classification criteria; (c) the disease activity assessment using the DAS28; (d) the differential diagnosis and how you would exclude the key mimics; (e) the investigations you would arrange; and (f) the integrated management plan including the hand-specific functional and pharmacological interventions. [1]

Model Answer

(a) The six-step examination routine (4 marks): [1]

My systematic routine is performed in the same order every time: inspection, palpation, range of motion, function, additional sites, and neurovascular assessment. Each step builds on the last and contributes to the diagnosis. [1]

On inspection, the symmetrical deformity pattern with ulnar deviation and palmar subluxation at the MCPs, the swan-neck deformity (PIP hyperextension with DIP flexion), the Z-deformity of the thumb, and the sparing of the DIP joints frame the diagnosis of rheumatoid arthritis at a glance. The soft, boggy quality of the swelling distinguishes synovitis from the bony osteophytes of osteoarthritis. The rheumatoid nodules on the extensor surface indicate seropositive, more aggressive disease. [1]

On palpation, I confirm the synovitis at each joint by feeling for boggy, warm, tender swelling. I feel the temperature (warm — active inflammation), the texture (no sclerodactyly — rules out systemic sclerosis), and the crepitus (soft in RA, not the coarse bony crepitus of OA). I squeeze across the metacarpal heads and palpate each PIP and DIP individually, counting the swollen and tender joints for the DAS28. [1]

On range of motion, I test active movement at the MCPs (make a fist), the PIPs and DIPs, the wrists (flex, extend, ulnar and radial deviate), and the thumb (opposition). If active is limited, I test passive to distinguish a fixed structural deformity from pain limitation. [1]

On function, I test grip strength (squeezing my fingers), pinch grip (the OK sign), writing the name, picking up a coin, and turning a key. These five tasks reveal the real-world impact and are mandatory in the DCE. [1]

On additional sites, I examine the elbows for rheumatoid nodules and psoriatic plaques, the shoulders for glenohumeral involvement and rotator cuff pathology, and I note the cervical spine for atlantoaxial subluxation risk. [1]

On neurovascular, I palpate the radial pulse and assess capillary refill, test median and ulnar nerve sensation, and perform the Tinel sign and the Phalen test for carpal tunnel syndrome — a common complication of RA from flexor tenosynovitis at the wrist. [1]

(b) Diagnosis and classification criteria (4 marks): [1]

The most likely diagnosis is seropositive rheumatoid arthritis with active synovitis and extra-articular nodular disease. The symmetrical small-joint polyarthritis involving the MCPs, PIPs, and wrists with sparing of the DIP joints, the boggy warm tender swelling indicating active synovitis, the prolonged morning stiffness, and the rheumatoid nodules (indicating seropositive disease) are the classic clinical picture. [1]

The 2010 ACR/EULAR classification criteria classify definite RA when there is synovitis in at least one joint, no better alternative diagnosis, and a score of six or more from four domains: joint involvement (based on the number and size of small and large joints involved), serology (RF and anti-CCP), acute phase reactants (CRP and ESR), and symptom duration (at least six weeks) [1]. This patient, with 14 swollen joints including small joints, a high ESR, and symptoms lasting years, clearly meets these criteria.

(c) Disease activity assessment with DAS28 (3 marks): [1]

The DAS28 is the standard composite measure of RA disease activity [2]. The 28 joints assessed are the ten MCPs, the ten PIPs, both wrists, both elbows, both shoulders, and both knees. The DIPs, ankles, and MTPs are not counted. For each joint, I record whether it is swollen and whether it is tender, giving a swollen joint count (here 14 of 28) and a tender joint count (here 18 of 28). The DAS28 combines these counts with the ESR (here 52 mm per hour) and the patient global assessment on a visual analogue scale.

The thresholds are: over 5.1 is high disease activity, 3.2 to 5.1 is moderate disease activity, 2.6 to 3.2 is low disease activity, and under 2.6 is remission. This patient, with 14 swollen joints, 18 tender joints, and an ESR of 52, is in high disease activity and requires escalation of DMARD therapy under the treat-to-target strategy, aiming for remission or low disease activity. [1]

(d) Differential diagnosis and exclusion of mimics (3 marks): [1]

The differential diagnosis of a symmetrical inflammatory small-joint polyarthritis includes: rheumatoid arthritis (the leading diagnosis), psoriatic arthritis (symmetrical variant), systemic lupus erythematosus (Jaccoud arthropathy), viral arthritis (parvovirus B19, hepatitis B and C, rubella), and crystal arthropathy (polyarticular gout or pseudogout). [1]

I exclude the mimics by: checking the DIP joints and the nails (PsA spares the MCPs and involves the DIP, with nail pitting and dactylitis), testing the reducibility of the deformities (Jaccoud arthropathy of SLE is reducible and non-erosive), taking a drug, alcohol, and viral exposure history (viral arthritis is acute and self-limiting, usually resolving within six weeks), and checking the serum urate and examining for tophi (polyarticular gout produces chalky white tophi and episodic acute attacks). The ANA, anti-dsDNA, RF, anti-CCP, and viral serology will discriminate in the laboratory phase. [1]

(e) Investigations (3 marks): [1]

I would arrange: a full blood count (anaemia of chronic disease, thrombocytosis in active inflammation), ESR and CRP (inflammatory markers), rheumatoid factor and anti-CCP (serology — anti-CCP is more specific for RA), ANA and anti-dsDNA (to screen for SLE), serum urate (to exclude gout), LFTs and U and E (baseline before DMARD therapy), viral serology (parvovirus B19, hepatitis B and C, HIV if indicated), and hand and foot X-rays (looking for periarticular osteopenia, marginal erosions at the MCPs and MTPs, and joint space narrowing — the characteristic radiographic features of RA). [1]

I would also arrange a chest X-ray and consider pulmonary function tests (RA is associated with interstitial lung disease and pleural disease), and an echocardiogram if there are cardiovascular concerns. [1]

(f) Integrated management plan (3 marks): [1]

The management is integrated and multidisciplinary: [1]

Pharmacological: Early and aggressive DMARD therapy is the cornerstone, initiated within the window of opportunity (the first three to six months). The treat-to-target strategy aims for remission or low disease activity. First-line is conventional synthetic DMARDs: methotrexate (the anchor drug, 10 to 25 mg once weekly, oral or subcutaneous, with folic acid supplementation), often combined with sulfasalazine and hydroxychloroquine (triple therapy). If the target is not met, escalate to biologic DMARDs (TNF inhibitors, rituximab, tocilizumab, abatacept) or targeted synthetic DMARDs (JAK inhibitors). Short-term oral or intra-articular corticosteroids for bridge therapy during flares. NSAIDs for symptomatic pain relief. [1]

Non-pharmacological and functional: Referral to a hand therapist for joint protection education, splinting (resting splints for the wrists during flares, working splints for activity), range of motion exercises to prevent contracture, and strengthening exercises. Occupational therapy for aids and adaptations (tap turners, jar openers, button hooks). [1]

Surgical: Referral to a hand surgeon for consideration of synovectomy, tendon repair or reconstruction (for extensor tendon rupture), joint arthroplasty (silicone implant arthroplasty for destroyed MCPs), or wrist fusion — in the patient with pain or functional loss unresponsive to medical therapy. [1]

Longitudinal: Regular rheumatology review with serial DAS28 assessments, annual cardiovascular risk assessment (RA carries an increased cardiovascular risk equivalent to diabetes), bone density monitoring (osteoporosis risk from both the disease and the corticosteroids), and vaccination (influenza, pneumococcal, hepatitis B, and zoster before starting biologics). [1]

SAQ 2 — Psoriatic Arthritis Hand Examination: The Dactylitis and Nail Changes (10 marks, 15 minutes)

Prompt: A 38-year-old man presents with uniform swelling of the entire left fourth finger (dactylitis), isolated swelling of the right index distal interphalangeal joint, nail pitting and onycholysis of multiple nails, and well-demarcated scaly plaques on the extensor surfaces of both elbows and at the umbilicus. Address: (a) the most likely diagnosis; (b) the classification criteria and how this patient meets them; (c) how you distinguish this from rheumatoid arthritis; and (d) the key hand findings that are pathognomonic for this condition. [1]

Model Answer

(a) Diagnosis (2 marks): The most likely diagnosis is psoriatic arthritis, distal interphalangeal predominant pattern, with dactylitis, nail involvement, and psoriatic skin disease. [1]

(b) Classification criteria (3 marks): The CASPAR criteria (Classification Criteria for Psoriatic Arthritis) require inflammatory articular disease (joint, spine, or entheseal) plus at least three points from: current psoriasis (2 points), a personal history of psoriasis (1, unless current psoriasis is present), a family history of psoriasis (1), current dactylitis or a history recorded by a rheumatologist (1), radiographic juxta-articular new bone formation (1), rheumatoid factor negativity (1), and nail dystrophy including onycholysis, pitting, and hyperkeratosis (1) [3]. This patient scores at least: current psoriasis (2) plus dactylitis (1) plus nail dystrophy (1) plus RF negativity (assumed, 1) — a total of 5, well above the threshold of 3.

(c) Distinction from RA (3 marks): Psoriatic arthritis differs from RA in five key respects: (1) the distribution is asymmetrical, not symmetrical; (2) the DIP joints are commonly involved (RA spares them); (3) dactylitis (sausage digit) is characteristic and is not seen in RA; (4) nail changes (pitting, onycholysis) are present in PsA but absent in RA; and (5) the rheumatoid factor is typically negative in PsA, while it is positive in the majority of RA patients. The MCP joints, heavily involved in RA, are relatively spared in PsA. [1]

(d) Pathognomonic hand findings (2 marks): The dactylitis (sausage digit) — the uniform swelling of an entire digit from combined joint and tendon sheath inflammation — is the most specific sign of PsA at the hand. The nail pitting and onycholysis, especially adjacent to an involved DIP joint, reflect the shared enthesis between the nail bed and the distal interphalangeal joint and are another hallmark. In advanced disease, the pencil-in-cup deformity at the DIP on X-ray and the telescoping of the fingers (arthritis mutilans, or opera-glass hand) are pathognomonic but now rare with modern therapy. [1]

Aletaha et al. (2010 ACR/EULAR RA criteria), Arthritis Rheum 2010; Prevoo et al. (DAS28), Arthritis Rheum 1995; Taylor et al. (CASPAR criteria), Arthritis Rheum 2006; Neogi et al. (2015 ACR/EULAR gout criteria), Arthritis Rheumatol 2015; Aringer et al. (2019 EULAR/ACR SLE criteria), Arthritis Rheumatol 2019; van den Hoogen et al. (2013 ACR/EULAR SSc criteria), Arthritis Rheum 2013; RACP DCE Examination Handbook; MRCP PACES. [1]