The Role of 3D Reconstruction True-Volume Analysis in Osteochondral Lesions of the Talus: A Case Series

Weight-Bearing CT for Diseases around the Ankle Joint

Weight-bearing computed tomography (WBCT) enables acquisition of three-dimensional bony structure images in a physiological weight-bearing position, which is fundamental in understanding the pathologic lesions and deformities of the ankle joint. Over the past decade, researchers have focused on validating and developing WBCT measurements, which has significantly enhanced our knowledge of common foot and ankle diseases. Consequently, understanding the application of WBCT in clinical practice is becoming more important to produce improved outcomes in the treatment of disease around the ankle joint. This review will describe an overview of what is currently being evaluated in foot and ankle surgery using WBCT and where the course of research will be heading in the future.

Enhancing precision in osteochondral lesions of the talus measurements and improving agreement in surgical decision-making using weight-bearing computed tomography and distance mapping

PURPOSE

Weight-bearing computed tomography (WBCT) enables the creation of a three-dimensional (3D) model that represents the ankle morphology in a standing position. Distance mapping (DM) is a complementary feature that uses color coding to represent the relative intraarticular distance and can be used to outline intraarticular defects. Consequently, DM offers a novel approach to delineating osteochondral lesions of the talus (OLT), allowing for the quantification of its surface, volume and depth. The reliability of DM for OLT measurements has yet to be thoroughly evaluated. This study primarily aims to determine the reliability of DM in measuring the surface, depth and volume of OLT. A secondary objective is to ascertain whether measurements obtained through DM, when integrated with a predefined treatment algorithm, can facilitate consensus among surgeons regarding the optimal surgical intervention.

METHODS

This cohort comprised 36 patients with 40 OLTs evaluated using WBCT and DM. Two raters used DM to determine the lesion boundary (LB) and lesion fundus (LF) and calculate the lesion depth, surface and volume. The raters were asked to choose between bone marrow stimulation, autologous matrix-induced chondrogenesis and osteochondral transposition based on the measurement. Inter-rater and intra-rater agreement was measured.

RESULTS

Interclass correlation of the lesion's depth surface produced an excellent inter-rater and intra-rater agreement of 0.90-0.94 p < 0.001. Cohen's κ agreement analysis of the preferable preoperative plan produced a κ = 0.834, p < 0.001, indicating a near-perfect agreement.

CONCLUSION

WBCT-based 3D modules and DM can be used to measure the lesion's surface, depth and volume with excellent inter-rater and inter-rater agreement; using this measurement and a predetermined treatment algorithm, a near-perfect inter-rater agreement for the preoperative planning was reached. WBCT in conjunction with AI capabilities could help determine the type of surgery needed preoperatively, evaluate the hindfoot alignment and assess if additional surgeries are needed.

LEVEL OF EVIDENCE

Level III.

Statistical shape modeling of mean shape and principal variability of the human talar bone in the Chinese population

PURPOSE

The talar bone plays a crucial role in ankle biomechanics and stability. Understanding the shape variability of the talar bone within specific populations is essential for various clinical applications. In this study, we aimed to investigate the mean shape and principal variability of the human talar bone in the Chinese population using statistical shape modeling (SSM).

METHODS

CT scans of 214 tali were included to create SSM models. Principal component analysis was used to describe shape variation among the male, female, and overall groups.

RESULTS

The largest amount of variation among three groups ranges from 17.2%-18.8% of each variation. The first seven principal components (modes) captured 62.4%-67.5% of the cumulative variance. No dominant shape of the talus was found. Male tali generally have a larger size than the female tali, with the exception of the articular surface of the anterior subtalar joint.

CONCLUSIONS

SSM is an effective method of finding mean shape and principal variability. Considerable variabilities were noticed among these three groups and all principal modes of variation. No dominant talar model was found to represent the majority of tali, regardless the gender. Such information is crucial to improve the current understanding of talar pathologies and their treatment strategies.

SPECT/CT imaging features of cystic degeneration of the talus and their relation to pathological findings

Background

Osteochondral lesions of the talus (OLTs) are a common orthopedic condition. The image presentation is very similar to that of ischemic necrosis of the talus complicated by a talar neck fracture, but the two are very different lesions. When abnormalities in bone density (or signal) of the talar body (apex of the fornix) with concomitant bone defects and cystic changes are found on X-ray, computed tomography (CT), or magnetic resonance imaging, it is important to accurately determine the nature of the lesion and make a correct diagnosis for the treatment and prognosis of the patient. The purpose of this study was to explore the imaging features of three-phase single-photon emission computed tomography (SPECT)/CT images of cystic lesions of the talus.

Methods

A total of 189 patients with chronic pain in the ankle joint suspected to be caused by cystic degeneration of the talus were enrolled. All patients underwent 99mTc-methyl diphosphonate (99mTc-MDP) three-phase SPECT/CT bone imaging and delayed scans in our hospital. The location, range of involvement, classification, CT value, and radioactivity uptake of the sclerotic areas of cystic lesions on the talus, and the continuity of the articular surface, were recorded. All recorded parameters were analyzed in comparison with pathological results.

Results

Eighty-three percent (157/189) of the talar cysts were located on the medial fornix, largely involving the anterior middle part (43.27%), with larger cysts involving the posterior part (9.6%). Sixty-three percent (119/189) of the patients had type I lesions and 37% (70/189) had type II lesions. The articular surface of the medial dome of the talus was intact in all patients, but the subchondral bony articular surface was rough in 88% (166/189) of patients. The coincidence rate for the location, type, and range of involvement of cystic lesions with the pathological results was 87.83% (166/189). The mean CT value of the cystic lesions was 45 ± 15 HU (30–60 HU). The percentages of pathological chondrogenesis in high CT value ≥ 50 HU (19/70) and low CT value < 50 HU (51/70) groups were 89.47% (17/19) and 29.14% (15/51) (χ² = 20.12, p < 0.001), respectively. The target/background ratio (T/B ratio) of the radioactivity-uptake area of the talus vault was 2.0 ± 0.5 (1.5–2.5). The percentages of pathological new trabecular bone in those with a T/B ratio ≥ 2.0 (157/189) and T/B ratio < 2.0 (32/189) were 82.80% (130/157) and 25.00% (8/32; χ² = 45.08, p < 0.001), respectively.

Conclusions

Three-phase bone imaging could identify damage of the talus caused by cystic degeneration, while delayed SPECT/CT images showed advantages for displaying bone microstructure, blood supplement, and bone metabolism when examining the location, range of involvement, classification, and repair of cystic lesions of the talus.

Comparing the Efficacy of True-Volume Analysis Using Magnetic Resonance Imaging With Computerized Tomography and Conventional Methods of Evaluation in Cystic Osteochondral Lesions of the Talus: A Pilot Study

Background: Osteochondral lesions of the talus (OLT) often require advanced imaging if they prove to be refractory to preliminary microfracture. Orthopedic surgeons may misinterpret the size and morphology of the OLT when evaluating through conventional methods. The purpose of this study was to evaluate MRI as a modality for calculating true-volumes and compare its utility to that of CT true-volume and conventional methods of measuring lesion size.

METHODS

With IRB approval, an institutional radiology database was queried for patients with cystic OLT that had undergone and failed microfracture and had compatible CT and MR scans between 2011 and 2016. Five lesions, previously analyzed and described in the literature using CT true-volume, were selected. 10 orthopedic surgeons independently estimated the volume of these 5 OLT via standard MRI. Next, 3D reconstructions were created and morphometric true-volume (MTV) analysis measurements of each OLT were generated. The percent change in volumes from CT and MR was compared based upon MTVs determined from 3D reconstructive analysis.

RESULTS

The volume calculated using conventional methods in CT and MR scans grossly overestimated the size by of the OLT by 285-864% and 56-374% respectively when compared to 3D true-volume analysis of those CT and MR scans.

CONCLUSIONS

This study demonstrates that true-volume is more accurate for calculating lesion size than conventional methods. Additionally, when comparing MRI and CT, thin slice CT true-volume is superior to MRI true-volume. True-volume calculation improves accuracy with CT and MRI and should be recommended for use in revision OLT cases.Levels of Evidence: Level III: Case control study.

Both Magnetic Resonance Imaging and Computed Tomography Are Reliable and Valid in Evaluating Cystic Osteochondral Lesions of the Talus

Background

Compared with computed tomography (CT), magnetic resonance imaging (MRI) might overestimate the condition of osteochondral lesions of the talus (OLTs) owing to subchondral bone marrow edema and the overlying cartilage defect. However, no study has compared MRI and CT directly in evaluating OLTs with subchondral cysts.

Purpose

To compare the reliability and validity of MRI and CT in evaluating OLTs with subchondral cysts.

Study Design

Cohort study (diagnosis); Level of evidence, 2.

Methods

An institutional radiology database was queried for inpatients diagnosed with OLTs with subchondral cysts who had undergone surgical treatment between May 2015 and October 2019. A total of 48 patients met the inclusion criteria. Based on our measurement method, 2 experienced observers who were blinded to the study independently measured the length, width, and depth of the cysts using MRI and CT. The classification of cystic lesions was also performed based on MRI and CT findings.

Results

Interobserver reliability was almost perfect, with intraclass correlation coefficients (ICCs) ranging from 0.935 to 0.999. ICCs for intraobserver reliability ranged from 0.944 to 0.976. The mean size of cysts measured on MRI (length, 13.38 ± 4.23 mm; width, 9.28 ± 2.28 mm; depth, 11.54 ± 3.69 mm) was not significantly different to that evaluated on CT (length, 13.40 ± 4.08 mm; width, 9.25 ± 2.34 mm; depth, 11.32 ± 3.54 mm). The size of subchondral cysts was precisely estimated on both MRI and CT. The MRI classification and CT classification revealed almost perfect agreement (kappa = 0.831).

Conclusion

With our measurement method, both MRI and CT were deemed to be reliable and valid in evaluating the size of subchondral cysts of OLTs, and the MRI classification was well-correlated with the CT classification. The presented measurement method and classification systems could provide more accurate information before surgery.

Comparison of autologous osteoperiosteal cylinder and osteochondral graft transplantation in the treatment of large cystic osteochondral lesions of the talus (OLTs): a protocol for a non-inferiority randomised controlled trial

INTRODUCTION

Large cystic osteochondral lesions of the talus (OLTs) have been shown to have inferior clinical outcomes after reparative techniques such as bone marrow stimulation. Autologous osteochondral transplantation has been viewed as an alternative choice for treating these lesions, but donor-site morbidity has limited its application. Excellent clinical outcomes have been shown in repairing these types of lesions with autologous osteoperiosteal grafts, and these outcomes are achieved at a low cost and without donor-site morbidity in the normal knee joint. This will be the first randomised controlled trial to compare the two surgical techniques, and recommendations for the treatment of patients with large cystic OLTs will be provided.

METHODS AND ANALYSIS

A non-inferiority randomised controlled trial will be conducted. A total of 70 participants with clinically diagnosed large cystic OLTs will be randomly allocated to either the experimental group or the control group at a ratio of 1:1. The experimental group will be treated with autologous osteoperiosteal cylinder graft transplantation, while the control group will be treated with autologous osteochondral transplantation. The primary outcome measure will be the American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Score and the Short Form 12 (SF-12) questionnaire. Secondary outcome measures will include the secondary arthroscopy International Cartilage Repair Society score, the Magnetic Resonance Observation of Cartilage Repair Tissue score, the Tegner activity level score, the visual analogue scale, routine X-rays, CT and complications. These parameters will be evaluated preoperatively, as well as at 3, 6, 12, 24, 36 and 60 months postoperatively. In this trial, we hypothesised that both procedures offer good results for the treatment of patients with large cystic OLTs, and occurrence of donor-site morbidity in autologous osteoperiosteal cylinder graft transplantation group is less than that in autologous osteochondral transplantation group.

ETHICS AND DISSEMINATION

The current study was approved by the board of research ethics of Peking University Third Hospital Medical Science Research Ethics Committee. The results of this study will be presented at national and international conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03347877.