Painful arthroplasty with disproportionate pain: Recognition and management of complex regional pain syndrome

Table 1 Clinical features distinguishing complex regional pain syndrome from other causes of persistent pain following total joint arthroplasty[1,6,20-22]

Feature	CRPS	PJI	Aseptic loosening	Arthrofibrosis	Peripheral nerve injury
Typical onset	Usually within weeks of surgery	Early postoperative or delayed presentation	Gradual over months to years postoperatively	Weeks to months postoperatively	Immediate or early postoperative period
Pain character	Disproportionate burning pain with allodynia or hyperalgesia	Deep aching pain with swelling	Mechanical pain worsened with activity	Painful stiffness with restricted motion	Neuropathic pain in a defined nerve distribution
Sensory findings	Diffuse hypersensitivity	Typically absent	Absent	Absent	Sensory deficits localized to affected nerve
Skin/trophic changes	Color/temperature changes, edema, sweating changes, trophic changes	Local inflammatory changes possible	Absent	Absent	Typically absent
Range of motion	Pain-limited motion	Limited secondary to pain or effusion	May be painful with instability	Markedly restricted with firm mechanical endpoint	May be limited by pain or weakness
Motor findings	Weakness, tremor, or guarding	Usually absent	Mechanical instability possible	Joint stiffness predominant	Weakness in affected nerve distribution
Laboratory findings	Typically normal inflammatory markers	Elevated ESR and CRP; abnormal synovial fluid analysis	Typically normal inflammatory markers	Normal inflammatory markers	Normal inflammatory markers
Imaging findings	Usually normal or nonspecific	Evidence of effusion or implant-related infection	Radiolucent lines, component migration, or loosening	No implant failure; postoperative fibrosis may be present	Usually normal prosthetic image
Diagnostic considerations	Budapest criteria, multisystem involvement	Joint aspiration and culture remain diagnostic standard	Radiographic evidence of implant failure	Clinical restriction in motion without autonomic findings	Electromyography or nerve conduction studies may assist diagnosis

Complex regional pain syndrome features derived primarily from the Budapest criteria and current diagnostic guidelines. CRPS: Complex regional pain syndrome; PJI: Periprosthetic joint infection; ESR: Erythrocyte sedimentation rate; CRP: C-reactive protein.

Table 2 Summary of available evidence evaluating sympathetic nerve blocks in complex regional pain syndrome[12,18,31,33,35-37]

Ref.	Study type	Population	Arthroplasty specific	Block type	Take-home message	Duration of relief	Key limitations
Ferraro et al[31]	Overview of systematic reviews	Adults with CRPS	General CRPS	Multiple interventions including sympathetic blockade	Evidence remains low certainty; definitive benefit unclear	Variable	Limited high-quality trials
Lee et al[33]	Retrospective cohort	Lower-extremity CRPS	General CRPS	Lumbar sympathetic block with botulinum toxin A/B	Type B toxin produced longer pain relief	Approximately 15 days (type A) vs approximately 69 days (type B)	Small sample size; non-arthroplasty population
Hartrick et al[35]	Prospective observational study	CRPS patients	General CRPS	Sympathetic block	Early response associated with better outcomes	Variable	No standardized protocol; heterogenous population
Adam et al[12]	Case report	Multiple revision THA	THA	Sympathetic block	Marked pain reduction after failed treatments	Pain free at 6 months	Single case report
Zanotti et al[36]	Case report	Elective THA patients	THA	Sympathetic block	Progressive symptom resolution	Resolution by 8 months, symptom free at 6-year follow-up	Very small sample size
Royeca et al[37]	Case report	Post-TKA CRPS	TKA	Multimodal management (limited block data)	Highlights diagnostic difficulty and variable outcomes	Variable	Limited evidence; primarily descriptive
Harden et al[18]	Evidence-based review	CRPS patients	General CRPS	Sympathetic blockade	May provide temporary pain relief and facilitate rehabilitation	Variable	Limited high-quality evidence; variable response

Evidence types and methodological limitations are presented descriptively because this narrative review did not perform a formal systematic risk-of-bias or certainty-of-evidence assessment. CRPS: Complex regional pain syndrome; THA: Total hip arthroplasty; TKA: Total knee arthroplasty.