Identification of normal and pathological posterior inter-malleolar ligament with dedicated high-field vs low-field MRI. A pilot study

Morphological study of CT image of posterior pilon variant fracture and its possible clinical significance

OBJECTIVE

The incidence of posterior pilon variant fractures has been underestimated. The purpose was to study the characteristics of posteromedial (PM) and posterolateral (PL) fragments in CT imaging of posterior pilon variant fractures, and to provide help for clinical diagnosis and treatment.

METHODS

CT imaging data of 109 cases of posterior pilon variant fractures in our hospital from January 2013 to December 2020 were retrospectively analyzed. According to Mason and Molloy classification, PM fragments were further divided into pilon subtypes and avulsed subtypes. The largest actual area of fragments in axial and sagittal were selected as the study plane, and the maximum axial lengths of X, Y and Z, α angle, β angle, fragment area (S1-7) and fragment area ratio (FAR1-4), interfragmentary (IF) angle, and back of tibia (BT) angle were measured.

RESULTS

A total of 109 cases were included in this study, 61 of whom were pilon subtypes [90.16% were supination-external rotation (SER) injuries]. 48 cases were avulsed subtypes [81.25% were pronation-external rotation (PER) injuries]. Pilon subtypes were larger than avulsed subtypes in X, Y, Z, α₂ Angle, β₂ Angle, fragment area and ratio, and IF and BT angle (P < 0.05). There was no difference between α₁ and β₁ angle (P > 0.05).

CONCLUSION

The morphology of pilon subtype was larger than that of avulsion subtype. According to fragment size, morphology, and injury mechanism, two fragments of pilon subtype should be anatomic reduction and fixation. However, the PL fragment of avulsion subtype should to be fixed, while PM fragment may only need conservative treatment.

CT Analysis of the Posteromedial Fragment of the Posterior Malleolar Fracture

BACKGROUND

To date, there have been no studies describing the characteristics of posteromedial fragment in the posterior malleolus fracture. The aim was to investigate the variability of posteromedial fracture fragments to enable better surgical planning.

METHODS

All Mason and Molloy type 2B fractures, defined as fracture of both the posterolateral and the posteromedial fragments of the posterior malleolus, from our database were identified to analyze the preoperative computed tomography scan. The posteromedial fragment was investigated in 47 cases (mean age, 46.6 years; 11 male, 36 female).

RESULTS

Morphologically, the fracture could be divided into 2 subtypes: (1) a large pilon intra-articular fragment (mean of X axis: 33.0 mm, Y: 30.7 mm, Z: 31.7 mm) presented in 29 cases with mean interfragmentary angle of 32.1 and back of tibia angle of 32.7 degrees (this was seen in 25 of 27 cases with supination injury pattern); and (2) a small extra-articular avulsion fragment (mean of X axis: 9.6 mm, Y: 13.2 mm, Z: 11.5 mm) present in 18 cases with a mean interfragmentary angle of 11.0 and back of tibia angle of 10.1 degrees. It was seen in 80% of pronation injuries.

CONCLUSION

The avulsion type of the posteromedial fragment of posterior malleolus fracture was more common in pronation injuries, likely the result of traction by the intermalleolar ligament, and the pilon type was more common in supination injuries, likely the result of the rotating talus impaction. Because of the intra-articular involvement, we believe the pilon type should undergo fixation to achieve articular congruity, unlike the avulsion type which may only function as a secondary syndesmotic stabilizer.

LEVEL OF EVIDENCE

Level III, retrospective comparative series.

The value of the simplified RAMRIS-5 in early RA patients under methotrexate therapy using high-field MRI

BACKGROUND

The aim of the study was to evaluate a simplified version of the Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) for five joints of the hand (RAMRIS-5) in patients with early rheumatoid arthritis (RA) before and after the initiation of methotrexate (MTX) therapy using high-resolution, 3-T magnetic resonance imaging (MRI).

METHODS

Twenty-eight patients with a seropositive, early RA (disease duration of less than 6 months (range 2-23 weeks)) according to 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) criteria (mean age 56.8 years, range 39-74) were prospectively assessed with a baseline investigation including clinical assessment (disease activity score of 28 joints (DAS-28) and C-reactive protein (CRP)) and 3-T MRI of the clinically dominant hand. Follow-up visits were performed 3 and 6 months after initiation of a MTX therapy at baseline. MRI scans were analyzed in accordance with RAMRIS and the simplified RAMRIS-5.

RESULTS

DAS-28 and CRP decreased significantly after initiation of MTX therapy. Even though erosion scores increased over time, RAMRIS and RAMRIS-5 also decreased significantly after the start of therapy. There was a strong correlation between the total RAMRIS-5 and RAMRIS at baseline (r = 0.838; P <0.001) and follow-up (3 months: r = 0.876; P <0.001; 6 months: r = 0.897; P <0.001). In the short term (3-month follow-up), RAMRIS and RAMRIS-5 demonstrated similar ability to detect changes for all subgroups (bone edema, erosion, and synovitis). In the long-term comparison (6-month follow-up), RAMRIS-5 also showed similar effectiveness when detecting changes in bone edema and erosion compared with RAMRIS. Deviations occurred regarding only synovitis, where change was slightly higher in RAMRIS-5: SRM (RAMRIS) = 0.07 ± 0.14; SRM (RAMRIS-5) = 0.34 ± 0.06.

CONCLUSIONS

Three-Tesla MRI-based RAMRIS-5 is a simplified and resource-saving RAMRIS score which compares favorably with the RAMRIS when detecting changes in early RA. Even though there is a slight abbreviation between RAMRIS-5 and the original score regarding the change of synovitis, it may be used for diagnosis and therapy monitoring in follow-up evaluations.