The McElfresh and Dobyns system

The clinical-radiological, stability-oriented classification that considers:

•       The location and direction of the damaged area of the joint.

•       The presence and degree of underpronation or prolapse.

•       Joint behavior after closed fixation (fixable vs. non-fixable, stable vs. unstable).

•       Distinguish between simple and complex fractures (without displacement). This classification is closely related to the treatment of acute cases and helps determine the need for intraoperative stabilization.1

​

The McElfresh and Dobyns system: (i) emphasizes joint stability and post-alignment behavior; (ii) has a direct impact on decisions regarding emergency and early post-traumatic care; and (iii) is intuitive for traumatologists and vascular surgeons. However, it does not include a specific assessment of cartilage or intra-articular loose bodies, and therefore cannot be considered a universal system.

​

AO/OTA classification

The AO/OTA system provides a global alphanumeric classification scheme for fractures of the entire skeleton, including clusters. When classifying fractures of the MCF joint, they are coded as:

• 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

 

The present system is a universal standard and suitable for registries, epidemiological studies, and multicenter trials. The AO/OTA system enables comparison of the fractures in other areas. However, it has the following drawbacks: (i) the coding categories are relatively broad and not targeted at small funds; (ii) it does not reflect minor injuries to the articular surface or cartilage; and finally, (iii) it does not directly include a soft tissue stability assessment scheme.

​

Advanced arthroscopic classification (ACE-M):

The classification is based on four domains:

• Domain A - articular surface (A0-A3).

• Domain C - Cartilage integrity (C0-C3).

• Domain M - Mechanical stability (M0-M3).

• Domain E - Extraarticular data (E0-E3).

 

Each domain is scored from 0 (no relevant pathology) to 3 (most severe pathology).

 

Domain A - Articular surface:

• 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;

 

Domain C - Cartilage integrity;

• 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.

 

Domain M - Mechanical stability

• 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.

 

Domain E - Additional data

• 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.

 

The MCF joint fracture is summarized by a four-letter code (e.g., A2-C2-M1-E2), which provides a concise qualitative description that is directly related to arthroscopic findings.

 

The Arthroscopic Severity Assessment Scale (ASS-MCP)

This scale converts qualitative arthroscopic data into a numerical severity index. Eight components are scored on a scale of 0 to 3 (0=none, 3=most severe), yielding a total score of 0 to 24.4 (Tab.1).5,6

The interpretation of the total ASS-MCP score is as following:

• Grade I (0-6 points; minimum):

  • 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.

• Grade III (13-18 points; severe):

  • 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.

 

TABLE 1.  Arthroscopic Severity Assessment Scale for the metacarpophalangeal Joint (ASS-MCP)