A systematic review on diagnosing deltoid ligament injuries: are we missing a uniform standard

Key points

1. 0190% of studies relied on radiologic findings alone to decide whether to treat the deltoid ligament
2. 02The Medial Clear Space (MCS) was the most commonly assessed parameter, but cut-off values ranged from 1 mm to 6 mm
3. 03The external rotation stress test under fluoroscopy was the most frequently used stressed radiograph
4. 04Only 2 of 31 studies differentiated between the superficial (SDL) and deep deltoid ligament (DDL) preoperatively
5. 05MRI sensitivity/specificity for SDL injury was 83%/94% and for DDL 69%/98%, but MRI was used in only one study for diagnosis

How it was conducted

Design

Systematic review following PRISMA guidelines, with prospective registration (PROSPERO ID: CRD42022307112)

Databases searched

MEDLINE (PubMed), Scopus, Central, and EMBASE searched from inception to February 2022

Included studies

31 original clinical or cadaveric/biomechanical studies meeting PICOS criteria; biomechanical studies without a diagnostic approach were excluded

Data extracted

Study type, level of evidence, diagnostic methods used, differentiation of deltoid ligament layers, syndesmotic injuries, and cut-off values

Risk of bias

Assessed using the MINORS criteria; non-randomized non-comparative studies averaged 8/16, comparative studies 13/24, and RCTs 15/24

What they found

• 28 of 31 studies (90%) based indication to treat on radiologic findings only
• Stressed radiographs were used in 15 studies, unstressed radiographs in 7, one used both, and 4 did not specify
• The external rotation stress test (ERST) was the most applied stressed radiograph (n=12)
• MCS was the most commonly assessed parameter (n=27), either alone (n=22) or combined with other parameters (n=5)
• MCS cut-off values varied between 1 mm and 6 mm; 4 mm was the most frequently used value
• DeAngelis et al. reported a false-positive deltoid rupture rate of 54% when using 4 mm MCS as cut-off compared to arthroscopy
• MRI sensitivity/specificity for SDL injuries: 83%/94%; for DDL: 69%/98% compared to intraoperative findings (Crim et al.)
• Ultrasound sensitivity/specificity in fracture cases reported as high as 100%/90% (Rosa et al.), but only 1 study used sonography
• Only 2 studies (9%) differentiated between DDL and SDL preoperatively (one by MRI, one by sonography)
• 65% of studies did not differentiate between SDL and DDL for diagnostic purposes
• 81% of studies set the treatment indication at a single time point; 6 studies re-evaluated at different time points
• 18 of 31 studies differentiated between syndesmotic and deltoid ligament injury
• Non-randomized comparative studies averaged 13/24 MINORS points (n=16); RCTs averaged 15/24 (n=5)

Limitations

• Extreme heterogeneity across included studies in tests used, cut-off values, and timing makes pooled conclusions unreliable
• Restriction to English-language publications may have excluded relevant studies
• Studies with fewer than 10 patients were excluded, which may have omitted useful diagnostic data
• No included study used arthroscopy as a reference standard systematically, limiting evaluation of diagnostic accuracy

Why it matters

For patients

Patients with ankle fractures and suspected deltoid ligament injury may be over- or under-treated because no reliable, agreed-upon diagnostic test exists to identify this injury accurately before surgery.

For clinicians

Clinicians cannot directly compare outcomes across studies or choose a best diagnostic approach because cut-off values, imaging modalities, and timing of assessment vary enormously between published reports.

For readers

This review maps the current diagnostic chaos in deltoid ligament injury management and makes a clear case for high-quality RCTs and standardized diagnostic protocols before treatment efficacy can be properly evaluated.