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.