Distribution of Subchondral Bone Puncture Strength in the Talus and Tibial Plafond: A Biomechanical Study

Investigation on the contour and bone mineral density of the distal tibial cutting surface used for total ankle arthroplasty

PURPOSE

This study was designed to investigate (1) the contour of the distal tibial cutting surface, and (2) the bone mineral density (BMD) of the distal tibial cutting surface used during total ankle arthroplasty (TAA).

METHODS

Eight-four distal tibial models were created using foot and ankle computerized tomographic (CT) images taken from normal people. The distal tibial cutting surface for TAA was determined to be 10 mm proximal to the tibial plafond. The bony contour and BMD values were determined from the CT image at that level. A bounding box was made on the contour and the width and length of the contour was measured. Regional BMD was evaluated by Hounsfield units (HU) value measurement, with 7 regions of interest (ROI) on 8 different directions for all the 84 CT images. Two different observers made independent measurements and mean HU values for all the 56 ROIs were calculated.

RESULTS

Great variations were found among the contours of the cutting surface especially in term of the shape of the anterior and posterior tibial tubercle, and the fibular notch. These variations could be grouped into six categories. For the BMD of the cutting surface, the medial border of the cutting surface did not included cortical bone. The HU value of seven ROIs, which included cortical bone, were significantly greater than all the other ROIs. Few statistical differences were found by multiple comparisons among HU value of all the 49 ROIs without cortex.

CONCLUSIONS

Great variability existed in the shape and the BMD of the distal tibial cutting surface.

Osteochondral Lesions of the Distal Tibial Plafond: A Systematic Review of Lesion Locations and Treatment Outcomes

BACKGROUND

Osteochondral lesions of the tibial plafond (OLTPs) remain less common than osteochondral lesions of the talus (OLTs), but recognition of the condition has increased.

PURPOSE

To systematically evaluate the literature on lesion locations and treatment outcomes of OLTPs, whether in isolation or in combination with OLTs.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A search was performed using the PubMed, Embase, and CINAHL databases for studies on lesion locations or with imaging or treatment outcomes of OLTPs. Case reports and reports based on expert opinion were excluded. Lesion locations as well as outcome measure results were aggregated. The Methodological Index for Non-randomized Studies score was used to assess methodological quality when applicable.

RESULTS

Included in this review were 10 articles, all published in 2000 or later. Most studies were evidence level 4, and the mean Methodological Index for Non-randomized Studies score was 8.6 (range, 8-10). Overall, 174 confirmed OLTP cases were identified, and the mean patient age was 38.8 years. Of the 157 lesions with confirmed locations, the most common was central-medial (32/157; 20.4%). Of 6 studies on treatment outcomes, all but 1 evaluated bone marrow stimulation techniques. Microfracture of small lesions (<150 mm2) was the most common treatment utilized. Imaging and functional outcomes appeared favorable after treatment. The data did not support differences in outcomes between isolated OLTPs and OLTPs with coexisting OLTs.

CONCLUSION

Osteochondral lesions of the distal tibia most commonly occurred at the central-medial tibial plafond. Microfracture of small lesions was the most common treatment utilized, and clinical and magnetic resonance imaging results were favorable, although data were heterogeneous. Areas for future research include the following: the effect of patient factors and additional pathologies on outcomes; larger or deeper lesion treatment; more direct comparisons of outcomes between kissing or coexisting lesions and isolated lesions; and head-to-head comparison of treatments, such as microfracture, bone marrow-derived cell transplantation, and osteochondral autografts/allografts.