What are the Eichenholtz stages and Sanders‑Frykberg anatomical classifications used to grade Charcot arthropathy?

Grading Systems for Charcot Arthropathy

Charcot arthropathy is classified using two complementary systems: the Eichenholtz staging system (which describes disease activity and progression) and the Sanders-Frykberg anatomical classification (which describes the anatomical location of involvement).

Eichenholtz Staging System

The Eichenholtz classification describes three radiographic stages of disease progression, though this system has significant limitations as it misses the earliest stage 1:

Stage 0 (Not in Original Eichenholtz Classification)

• Clinical signs of inflammation (warm, red, swollen foot) with normal plain X-rays 2, 1
• Bone and joint abnormalities are only visible on MRI, not plain radiographs 2, 1
• This earliest stage can heal without significant arthropathy if treated promptly with offloading 1
• Critical pitfall: Eichenholtz failed to recognize this stage because he relied solely on plain X-rays, which led to inevitable progression to deformity in his patients 1

Stage I (Development/Fragmentation)

• Periarticular fragmentation and joint debris on imaging 3
• Active bone and joint destruction with fractures and dislocations 4
• Clinical signs of acute inflammation present 3

Stage II (Coalescence)

• Absorption of bone debris and early bone healing 3
• Beginning of fracture consolidation 4
• Decreased inflammation compared to Stage I 3

Stage III (Reconstruction/Consolidation)

• Complete bone healing and remodeling 3
• Residual deformity may be present 4
• Resolution of inflammation 3

Important limitation: The Eichenholtz classification showed only "moderate to good" inter-reader reliability (ICC 0.68-0.87) in validation studies, making it the least reliable of the major classification systems 3.

Sanders-Frykberg Anatomical Classification

This anatomical system demonstrates "excellent" inter-reader reliability (ICC 0.96-0.98) and is the most reliable classification for Charcot arthropathy 3:

Type I: Forefoot

• Involves metatarsophalangeal and interphalangeal joints 3, 4

Type II: Tarsometatarsal (Lisfranc) Joints

• Most common location of Charcot involvement 4, 5
• Affects the midfoot at the tarsometatarsal articulations 3

Type III: Naviculocuneiform, Talonavicular, and Calcaneocuboid Joints

• Midfoot involvement at Chopart's joint level 4, 6

Type IV: Ankle and Subtalar Joints

• Involves the tibiotalar and subtalar articulations 4, 6
• Often requires tibiocalcaneal arthrodesis when surgical intervention is needed 6

Type V: Calcaneus

• Isolated calcaneal involvement 3

Clinical Application and Reliability

The Sanders-Frykberg classification should be the primary anatomical classification system used, as it demonstrated superior reliability compared to the alternative Brodsky-Trepman system 3:

• Sanders-Frykberg: "Excellent" reliability (ICC 0.96-0.98) 3
• Brodsky-Trepman: "Good to excellent" reliability (ICC 0.81-0.93) 3
• Eichenholtz: "Moderate to good" reliability (ICC 0.68-0.87) 3

Modern Classification Considerations

A proposed MRI-based classification superseding Eichenholtz includes two severity grades (0 and 1, based on absence/presence of cortical fractures) and two stages (active/inactive, based on presence/absence of skeletal inflammation) 1. This addresses the critical limitation that the original Eichenholtz system missed the earliest, potentially reversible stage of disease.

Key clinical point: The combination of both systems provides comprehensive assessment—Sanders-Frykberg identifies the anatomical location for treatment planning, while staging (preferably MRI-based) determines disease activity and guides the intensity and duration of offloading treatment 3, 1.