Preliminary findings of morphometric analysis of ankle joint in Korean population

A bi-radial approach to define the sagittal geometry of the healthy ankle

BACKGROUND

Previous descriptions of the sagittal geometry of the tibia and talus have involved single radius curves. The purpose of this investigation was to: determine if the sagittal curvature of the medial and lateral sides of the talus and tibia can be described by dividing the condyles into anterior and posterior regions, determine tibiotalar congruency, and categorize the morphological configurations of the talus and tibia.

METHODS

Eighteen subjects underwent weightbearing CT scans and the osseous curvature was analyzed.

RESULTS

For the talus, the medial anterior radius was smaller than the lateral anterior radius. For the distal tibia, the lateral posterior radius was smaller than the medial posterior radius. Tibiotalar congruency varied by region. The most common geometric configuration was two cones, one anterior and one posterior, pointed in opposite directions.

CONCLUSION

The sagittal profiles of the tibia and talus can be more accurately described using a bi-radial approach as compared to a single radius.

Morphological variation of the hemophilic talus

Flattening of the trochlear tali is clinically observed as structural and functional changes advance in patients with hemarthropathy of the ankle. However, the degree of this flattening has not yet been quantified, and distribution of the morphological changes across the talus not yet defined. Chronologically sequential MR images of both a hemophilic patient group (N = 5) and a single scan from a nondiseased, sex-matched, control group (N = 11) were used to take four measurements of the trochlear talus morphology at three locations (medial, central and lateral) along the sagittal plane. Three ratios of interest were defined from these to assess whether the talar dome flattens with disease. The control group MRI measurements were validated against literature data obtained from CT scans or planar X-Rays. The influence of disease on talar morphology was assessed by direct comparison of the hemophilic cases with the control group. The values for all three ratios, in all locations, differed between the control and the hemophilic group. Flattening was indicated in the hemophilic group in the medial and lateral talus, but differences in the central talus were not statistically significant. This work demonstrates that morphological assessment of the talus from MR images is similar to that from CT scans or planar X-Rays. Talar flattening does occur with hemarthropathy, especially at the medial and lateral edges of the joint surface. General flattening of the trochlear talus was confirmed in this small patient sample, however the degree and rate of change is unique to each ankle.

Relevance of SPECT-CT in Complex Cases of Foot and Ankle Surgery: A Comparison With MRI

BACKGROUND

Finding the right diagnoses in patients with complex foot and ankle disorders can be challenging. Single-photon emission computed tomography and computed tomography (SPECT-CT) has shown to be feasible in foot and ankle surgery. The aim of this study was to evaluate the reliability and accuracy of SPECT-CT and thereby its impact on final treatment decision compared with magnetic resonance imaging (MRI).

METHODS

A retrospective study was performed on 49 patients treated at our institution. Experienced foot and ankle surgeons independently, and blinded, analyzed clinical data and radiographs together with MRI, SPECT-CT, or a combination of both. Based on the determined final treatment decision Cohen's kappa values were calculated to illustrate interrater and intrarater reliability.

RESULTS

The kappa values for interrater reliability were higher for SPECT-CT at .68 and MRI + SPECT-CT at .71 compared to 0.38 for MRI alone (P < .05). The kappa values for intrarater reliability of MRI + SPECT-CT were higher at .75 compared with SPECT-CT alone at .67 (P < .05) and MRI at .35 (P < .01).

CONCLUSION

We found a higher interrater and intrarater reliability for SPECT-CT compared with MRI alone for diagnosing complex foot and ankle pathologies. SPECT-CT has a high impact on final treatment decision. The main indications are bony pathologies with diagnostic uncertainty especially in closely adjacent structures as the joints of the midfoot, occult coalitio, stress fractures, verification or exclusion of nonfusion, periprosthetic disorders after total ankle replacement and osteochondral lesion in cases of combined pathologies.Levels of Evidence: Level IV: Retrospective study.

Quantitative evaluation of posterior talar subluxation in posterior malleolar fractures: A preliminary study

BACKGROUNDS

Although ankle posterior subluxation is one of the major mechanisms by which posterior malleolar fractures (PMF) contribute to a worse prognosis, there is no parameter to address it quantitatively. So, we suggest a method that can evaluate posterior talar subluxation quantitatively in PMF.

METHODS

We retrospectively analyzed 37 patients with posterior malleolar fractures. The patients were divided into two groups: PMF without posterior talar subluxation (n = 18) and with posterior talar subluxation (n = 19). We measured the distance between the arc center of the talus and the anterior tibia (TAD), the percentage of articular involvement of the fracture fragment, the inter-fragment distance (IFD) and articular step-off. We analyzed significant differences and the correlations between the two groups for each index. The estimated area of the receiver operating characteristic (ROC) curve was calculated, and cutoff values were suggested to discriminate posterior talar subluxation.

RESULTS

TAD, IFD, and articular step-off were significantly greater in patients with posterior talar subluxation. (TAD: 14.3 vs. 2.8 mm, p < 0.001, IFD: 7.8 vs. 4.0 mm, p < 0.001, articular step-off: 3.6 vs. 2.0 mm, p = 0.004). The ROC curve showed that TAD was most useful to determine cutoff values for posterior talar subluxation. The area under the curve for TAD was 1.000, and the appropriate cutoff value was 5 mm. When a TAD of > 5 mm was used as a threshold, a sensitivity of 100% and a specificity of 100% were achieved in determining the presence of posterior talar subluxation. Also, higher TAD was correlated with IFD and articular step-off.

CONCLUSIONS

TAD can be a useful parameter for evaluating the posterior talar subluxation in PMF. It can reflect not only the degree of fracture displacement but also posterior talar subluxation quantitatively.

Three-dimensional morphological analysis and clinical application of ankle joint in Chinese population based on CT reconstruction

PURPOSE

To study the anatomical features of the ankle joint in Chinese northeast healthy adults and provide accurate data for the design of the total ankle arthroplasty (TAA) prosthesis.

METHODS

Computer tomography (CT) images from 156 healthy subjects, 86 males and 70 females, were collected and reconstructed through Mimics software. The 3D morphology of the distal tibia/fibula section and the whole talar was analyzed by measuring 28 parameters including maximal tibial thickness (MTiTh), anterior-posterior inclination angle, trochlea tali width (TaW), distal tibial width (TiW) and trochlea tali arc chode length (TaAL) and calculating MTiTh/TiW, TaAL/TaW. Gender difference and accuracy of CT images were evaluated. The measurements were compared with previously reported data from Caucasian subjects and Asian subjects. Statistical analysis was conducted by independent-samples t test through SPSS software.

RESULTS

(1) Twenty two out of the 28 parameters were found significantly different between males and females. Most of the parameters in males were found larger than that in females (p < 0.05). (2) The difference was found larger in comparison with the Caucasian subject groups than that with Asian subject groups. (3) All the selected 11 parameters measured by CT images were found to be smaller than those by X-ray images (p < 0.05).

CONCLUSION

The morphological parameters were found different between the Caucasian and Chinese northeast populations. Precise data of the ankle joint morphology were provided for the design and clinical application of TAA in the Chinese population.

Ankle morphometry based on computerized tomography

BACKGROUND

Thorough understanding of the morphometry of the ankle joint is crucial to optimize conservative and operative therapy of ankle joint disorders. Despite recent improvements, basic anatomic and biomechanical correlations of the ankle joint including the orientation of the ankle joint axis and joint morphology as its key biomechanical features are not sufficiently recorded to date. The aim of this study was the evaluation of the ankle morphometry to gain information about the ankle joint axis.

MATERIAL AND METHODS

In this study 98 high-resolution CT-scans of complete Caucasian cadaver legs were analysed. Using the software Mimics and 3-Matic (Materialize) 22 anatomic parameters of the talocrural joint were assessed, including the length, width and surface area of the tibial and talar articular areas. Additionally, the radii of the articular areas, the medial distal tibial angle and the height of the talar dome were determined.

RESULTS

The radius of the central trochlea tali was 44.6±4.1mm (mean±SD). The central trochlea tali arc length was 40.8±3.0mm and its width was 27.4±2.5mm. Additionally we determined 47.0±4.4mm for the tibial sagittal radius, 27.6±3.0mm for the tibial arc length and 27.4±2.5mm for the central tibial width.

CONCLUSION

The present study describes the three-dimensional morphometry of Caucasian ankle joints in detail. This dimensional analysis of the ankle joint will inform the development and placements of implants and prostheses.