Kanavel's four cardinal signs of flexor tenosynovitis are one of the most important surgical emergency frameworks in hand surgery — they must be memorised by every GP who examines hands: (1) Finger held in slight flexion at rest (the position of minimum tenosynovial tension); (2) Uniform fusiform swelling of the entire finger ('sausage finger' — the swelling follows the tendon sheath from distal palm to fingertip); (3) Intense pain on passive extension of the finger (as the inflamed sheath is stretched); (4) Tenderness along the course of the flexor tendon sheath on palpation (palmar surface from A1 pulley to fingertip). Suspected pyogenic flexor tenosynovitis needs same-day ED/hand-surgery assessment — not every case needs a 999 ambulance. The flexor tendon sheath is a closed space with poor blood supply, and delay may result in tendon necrosis, adhesions, stiffness and loss of function; treatment may involve operative washout, IV antibiotics chosen by local microbiology guidance, elevation and splinting.

Dupuytren's contracture management briefly included collagenase clostridium histolyticum (Xiapex), but it was withdrawn from the UK and EU market in March 2020 and NICE TA459 was withdrawn — current options are needle fasciotomy and fasciectomy. GPs should know the referral criteria for this condition (more common in men, older age, Northern European descent, diabetes, alcohol, epilepsy/phenobarbitone). The tabletop test is a useful functional assessment, but a positive test is not automatically a reason for referral within 1–2 weeks. Refer routinely to hand surgery/hand therapy if contracture affects function, MCP contracture is approximately 30° or more, there is progressive PIP contracture, the patient cannot place the hand flat, or there is diagnostic uncertainty or concern about another mass; increase urgency with rapid progression, severe functional limitation or neurovascular compromise. The MCP joint contracture at ≥30° is the standard threshold for intervention (percutaneous needle fasciotomy or surgical fasciectomy; collagenase (Xiapex) is no longer available in the UK). Needle fasciotomy: cord divided percutaneously under local anaesthetic — quicker recovery but higher recurrence; lower efficacy for PIP contractures. Surgical fasciotomy/fasciectomy: higher correction rate, more invasive. GPs who observe progressive Dupuytren's contracture without referral when the patient has functional impairment are missing an intervention window.

The joint aspiration and synovial fluid analysis is the single most important investigation in distinguishing septic arthritis from crystal arthropathy (gout or pseudogout) in an acutely swollen hot joint — and GPs cannot usually perform this in primary care, making prompt same-day hospital assessment essential. The synovial fluid findings: septic arthritis: turbid fluid, raised white cell count (predominantly polymorphs), organisms on Gram stain or culture — a negative Gram stain does not exclude infection. Gout: needle-shaped negatively birefringent sodium urate crystals under polarised light microscopy. CPPD (pseudogout): positively birefringent rhomboid calcium pyrophosphate crystals. The critical overlap: septic arthritis and crystal arthropathy can coexist in the same joint — a crystal-positive fluid does not exclude concurrent infection. Do not delay transfer for community investigations: the receiving service arranges aspiration where feasible, and antibiotics are given promptly after cultures unless the patient is septic or clinically unstable.

Anti-CCP is a useful test for rheumatoid arthritis, and positivity predicts a more erosive disease course — but referral is driven by the clinical finding of persistent synovitis, not by serology. NICE NG100 recommends urgent specialist referral for persistent synovitis of undetermined cause, especially with small hand/foot joint or multiple joint involvement, or a delay of 3 months or more before presentation, even if RF, anti-CCP and inflammatory markers are normal. Rheumatology aims to start conventional DMARD treatment as soon as possible, ideally within 3 months of onset of persistent symptoms, because early treatment can prevent joint destruction, deformity and disability. The practical primary care standard: request RF (anti-CCP if RF negative) and ESR/CRP at the same consultation, but make the urgent rheumatology referral at the same time rather than waiting for the results.

Corticosteroid injection for trigger finger can be offered in primary care where the clinician is trained and the local protocol permits, and never when infection is suspected. The injection is given at the A1 pulley (proximal flexor crease, over the MCP joint) into the tendon sheath, not the tendon. Preparation, dose and any repeat interval should come from the local formulary/procedure protocol rather than a generic algorithm. Discuss recurrence, skin depigmentation/subcutaneous atrophy, transient hyperglycaemia (warn people with diabetes), infection and tendon injury. Review according to symptoms, complications, diabetes control and the local procedure protocol.

Colchicine prophylaxis when initiating allopurinol helps prevent the well-known phenomenon of mobilisation gout — when urate-lowering therapy begins, the rapid fall in serum urate mobilises monosodium urate crystals from existing tissue deposits, triggering inflammatory attacks. Flares are common in the first months of urate-lowering therapy and many patients stop allopurinol, incorrectly attributing the flares to the drug itself. NICE NG219 recommends discussing flare prophylaxis and, if the person chooses it, offering colchicine while titrating, if suitable (dose per NICE/SPC, with attention to renal/hepatic function, age and interacting medicines). The critical prescribing communication: 'Allopurinol is working correctly even if you get a gout attack in the first few months — do not stop the allopurinol. The colchicine is to protect you during this initial period.'

DMARD monitoring in primary care is a shared-care responsibility that requires systematic organisation, but there is no single schedule for all DMARDs: monitoring varies with the drug, dose and duration, renal/hepatic function, abnormal results or dose changes, and specialist advice. Use the local shared-care protocol for the particular DMARD, including its action thresholds, and keep a clear monitoring template in the clinical record. The MHRA Yellow Card scheme should be used to report serious adverse effects.

The HAVS (Hand-Arm Vibration Syndrome) is an occupationally prescribed disease that GPs can diagnose and facilitate compensation claims for — it affects workers using vibrating hand-held tools (pneumatic drills, grinders, chainsaws, road breakers) and causes: Raynaud's phenomenon of the fingers (vibration white finger — a specific occupational form of Raynaud's), sensorineural hand-arm vibration (SNHAV — peripheral neuropathy causing tingling, numbness, reduced grip), and musculoskeletal effects (carpal tunnel syndrome, reduced dexterity). Exposure is regulated by the Control of Vibration at Work Regulations 2005 (employers report diagnosed HAVS under RIDDOR), and it is a Prescribed Disease under the Industrial Injuries Disablement Benefit scheme (PD A11 for the vascular and sensorineural components; PD A12 for carpal tunnel syndrome from vibrating tools). GPs who see construction or manufacturing workers with Raynaud's or neuropathic hand symptoms should take a detailed occupational history (years of vibration tool use, daily exposure hours) and refer to the occupational health physician for formal HAVS assessment (the employer, not the GP, makes the RIDDOR report).

The 'safe splinting' principle for mallet finger must be communicated precisely to patients — failure to maintain the DIP joint in continuous extension is a common reason for treatment failure. The splint keeps the DIP extended while allowing PIP movement, and the patient should understand that accidental DIP flexion usually means restarting the period of continuous splinting; follow the local hand-therapy protocol on duration and night splinting. The correct patient instruction: 'When you need to clean under the splint, hold the finger completely straight with your other hand before removing the splint, then slide the splint off — keeping the finger extended throughout. Clean underneath it while keeping the finger straight, then slide the splint back on.' A patient who removes a mallet splint without understanding this principle risks treatment failure. Document this instruction in the clinical notes.