Comparative Analysis of Metacarpophalangeal Joint Fracture Classifications
DOI:
https://doi.org/10.52340/GBMN.2026.01.01.155Keywords:
ACE M, AO/OTA, arthroscopy, ASS MCP, fracture classification, McElfresh and Dobyns, metacarpal head fracture, metacarpophalangeal jointAbstract
Metacarpophalangeal joint fractures are complex injuries involving bone, cartilage, and soft tissue, and therefore require a multidimensional approach. To compare the main classification systems for metacarpophalangeal (MCP) joint fractures and to introduce an extended arthroscopic classification and severity score integrating articular morphology, cartilage integrity, mechanical stability, and associated intra-articular pathology. A narrative review of the literature on MCP and metacarpal head fractures was performed, focusing on the McElfresh & Dobyns classification, the AO/OTA fracture classification, and arthroscopy-based systems. The McElfresh & Dobyns system emphasizes clinical-radiologic stability and is particularly useful for fracture-dislocations. The AO/OTA classification offers universal alphanumeric coding but is relatively coarse for small joints. Arthroscopy allows direct assessment of cartilage lesions, ligamentous integrity, loose bodies, and synovitis. The proposed ACE M classification grades four domains (A0-A3, C0-C3, M0-M3, E0-E3) and yields a concise four-letter profile. The ASS MCP score sums eight components (0-3 points each; total 0-24) and stratifies injuries into four grades, each linked to a specific treatment pathway and prognosis. Low scores (Grade I-II) favor arthroscopic or arthroscopically assisted procedures, whereas high scores (Grade III-IV) usually require combined or open approaches. Based on the literature review, no single system fully captures the complexity of MCP joint fractures. Radiographic stability-oriented (McElfresh & Dobyns), universal (AO/OTA), and arthroscopic (ACE M, ASS MCP) classifications are complementary. The combined use of these systems enables multidimensional description, more precise treatment planning, and more informative reporting in clinical studies.References
Standardized description of fracture patterns.
Effective communication between clinicians.
Rational choice between conservative and operative treatment.
Comparison of outcomes in clinical research.
"Metacarpophalangeal joint fracture",
"Metacarpal head fracture",
"Fracture-dislocation",
"Classification",
"McKelfresh", "Dobbins", "AO/OTA",
"MCP arthroscopy", "Arthroscopic classification."
Original descriptions or substantive discussions of the McElfresh and Dobbins and AO/OTA classifications that addressed MCP/metacarpal head and proximal phalanx fractures.1,2
Studies or reports describing arthroscopic findings and classification concepts in metacarpophalangeal joint fractures or osteochondral lesions.
Articles that provided sufficient detail to understand the structure, use, and limitations of the classification;
Formal quality assessment or meta-analysis was not conducted due to the heterogeneity and conceptual nature of the topic.
By bone and segment (metacarpal head, diaphysis, base);
Depending on the extent of damage to the articular surface (extraarticular, partially intra-articular, fully intra-articular).
By complexity (simple, wedge-shaped, complex/comminuted). Thus, metacarpal head fractures are assigned a specific code indicating the bone, segment, and type of joint involvement.2
Domain A - articular surface (A0-A3).
Domain C - Cartilage integrity (C0-C3).
Domain M - Mechanical stability (M0-M3).
Domain E - Extraarticular data (E0-E3).
A0: Extraarticular; no intraarticular extension, unchanged surface, no step.
A1: Minimal intra-articular damage (<25% surface), single fragment, <2 mm misalignment, stable configuration.
A2: Moderate intra-articular injury (25-50% surface area), 2-3 fragments, 2-4 mm misalignment, potentially unstable fracture.
A3: Extensive intra-articular injury (>50% surface area), ≥3 fragments or comminuted, ≥4 mm misalignment, substantially unstable;
C0: Intact cartilage, smooth articular surface, no defects.
C1: Superficial damage to the articular cartilage (Outerbridge I-II), softening or fibrillation, without full-thickness damage.
C2: Deep chondral damage to the articular cartilage (Outerbridge III), partial thickness tears in the cartilage, exposed subchondral bone.
C3: Severe chondromalacia (Outerbridge IV), full-thickness loss of cartilage with large exposed bone defects.
M0: Stable joint; collateral ligaments and volar plate intact; no subluxation.
M1: Partial instability; ligament sprain or partial tear; correctable subluxation.
M2: Unstable joint; complete ligament tear or volar plate avulsion; persistent subluxation.
M3: Dislocated joint; complete disruption of the joint, dislocation difficult to correct without manipulation or open intervention; multiple soft tissue injuries.
E0: No changes; clean joint, without loose bodies and synovitis.
E1: Minor changes; mild synovitis, small cartilage fragments, minimal hemarthrosis.
E2: Significant changes; moderate-severe synovitis, multiple loose bodies (>3), large osteochondral fragments.
E3: Major changes; capsule tear, extensor mechanism damage, neurovascular involvement.
Grade I (0-6 points; minimum): Arthroscopic debridement ± percutaneous fixation. Excellent prognosis; return to activity ≈in 6-8 weeks.
Arthroscopic debridement ± percutaneous fixation.
Excellent prognosis; return to activity ≈in 6-8 weeks.
Grade II (7-12 points; moderate): Arthroscopic-assisted repositioning and internal fixation. Good to excellent prognosis; recovery ≈10-12 weeks.
Arthroscopic-assisted repositioning and internal fixation.
Good to excellent prognosis; recovery ≈10-12 weeks.
Grade III (13-18 points; severe): Combined arthroscopic and mini-open approach; joint restoration as needed. Satisfactory-good prognosis; return ≈14-16 weeks.
Combined arthroscopic and mini-open approach; joint restoration as needed.
Satisfactory-good prognosis; return ≈14-16 weeks.
Grade IV (19-24 points; critical): Open reduction and internal fixation, with possible consideration of arthroplasty. Cautious prognosis; return >16 weeks, high risk of residual symptoms.
Open reduction and internal fixation, with possible consideration of arthroplasty.
Cautious prognosis; return >16 weeks, high risk of residual symptoms.
The McElfresh and Dobyns systems are still helpful for preoperative radiographic and clinical evaluation.
AO/OTA ensures compatibility with international fracture registries.
ACE-M and ASS-MCP improve intraoperative decision making and may improve prognostic accuracy, particularly in centers routinely performing MCP arthroscopy.
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