The EOS 3D imaging system reliably measures posterior tibial slope

Tibial derotational osteotomy for idiopathic tibial torsion: A systematic review of surgical indications based on clinical presentation and measurement technique

PURPOSE

The aim of this systematic review was to identify the surgical indications of tibial derotational osteotomy (TDO) in patients with idiopathic external tibial torsion (ETT) and identify common measurement thresholds for surgical correction.

METHODS

A systematic search of MEDLINE and Embase via Ovid, Cochrane Library via Wiley, Web of Science, Scopus, SPORTDiscus via EBSCOhost, ClinicalTrials.gov, WHO ICTRP and Global Index Medicus databases was performed with search terms reflecting the concepts of idiopathic tibial torsion, TDOs, and surgical indications. Studies reporting surgical indications and measurement methods of idiopathic tibial torsion in patients who underwent TDO were included. Two authors independently screened articles and extracted data that was characterized with descriptive statistics.

RESULTS

Seventeen studies were identified for inclusion, with 460 tibias and 351 patients. Nearly all patients who underwent surgery had either anterior knee pain or patellar instability, even if other indications were present. Of all included patients, the most common surgical indications for TDO were anterior knee pain (88%), patellar instability (59%), gait dysfunction (41%) and cosmetic deformity (12%). Twelve studies (71%) cited multiple of these indications as reasons for surgery. On physical exam, tibial torsion was measured most commonly by thigh-foot angle (59%) (TFA) and transmalleolar axis (24%) (TMA). In terms of TFA, the most frequently reported cut-off for ETT was >30° (35%). Computerized tomography (CT) was used by nine studies (53%). The most common CT axes used to measure ETT were the TMA with respect to the posterior tibia condylar axis or the bicondylar tibia axis.

CONCLUSION

Anterior knee pain and/or patellar instability are common indications for TDO in patients with idiopathic tibial torsion. Standardized TFA thresholds (>30°) and CT measurement methods (TMA and posterior tibia condylar or bicondylar tibial axis) may help further establish objective surgical indications.

LEVEL OF EVIDENCE

IV.

Measurement of tibial slope using biplanar stereoradiography (EOS®)

OBJECTIVES

Posterior tibial slope (PTS) is an important anatomic parameter of the knee related to anteroposterior instability. Biplanar stereoradiography allows for simultaneous low-dose acquisition of anteroposterior and lateral views with 3D capability, enabling separate lateral and medial plateau analyses. We aimed to evaluate the possibility and compare the reproducibility of measuring medial and lateral PTS on EOS® images with two different patient positionings and compare it with CT of the knees as the gold standard.

METHODS

This is a retrospective study including volunteers who underwent lower limb stereoradiography and knee CT from 01/08/2016 to 07/31/2019. Sixty legs from 30 patients were studied. PTS were measured using stereoradiography and CT by two radiologists. Intraclass correlation was used to calculate intrarater and interrater reproducibilities. Pearson's correlation coefficients were used to calculate the correlation between stereoradiography and CT. We also compared the reproducibility of the stereoradiography of volunteers with 2 different positionings.

RESULTS

The mean stereoradiography PTS values for right and left knees were as follows: lateral, 12.2° (SD: 4.1) and 10.1° (SD: 3.5); medial,12.2° (SD: 4.4) and 11.6° (SD: 3.9). CT PTS mean values for right and left knee are as follows: lateral, 10.3° (SD:2.5) and 10.6° (SD: 2.8); medial: 8.7° (SD: 3.7) and 10.4° (SD: 3.5). Agreement between CT and EOS for angles between lateral and medial PTS was good (right, 0.874; left, 0.871). Regarding patient positioning on stereoradiography, interrater and intrarater reproducibilities were greater for patients with nonparallel feet (0.738-0.883 and 0.870-0.975).

CONCLUSIONS

Stereoradiography allows for appropriate delineation of tibial plateaus, especially in patients with nonparallel feet, for the purpose of measuring PTS. The main advantage is lower radiation doses compared to radiography and CT.

Deep learning-based identification of spine growth potential on EOS radiographs

OBJECTIVES

To develop an automatic computer-based method that can help clinicians in assessing spine growth potential based on EOS radiographs.

METHODS

We developed a deep learning-based (DL) algorithm that can mimic the human judgment process to automatically determine spine growth potential and the Risser sign based on full-length spine EOS radiographs. A total of 3383 EOS cases were collected and used for the training and test of the algorithm. Subsequently, the completed DL algorithm underwent clinical validation on an additional 440 cases and was compared to the evaluations of four clinicians.

RESULTS

Regarding the Risser sign, the weighted kappa value of our DL algorithm was 0.933, while that of the four clinicians ranged from 0.909 to 0.930. In the assessment of spine growth potential, the kappa value of our DL algorithm was 0.944, while the kappa values of the four clinicians were 0.916, 0.934, 0.911, and 0.920, respectively. Furthermore, our DL algorithm obtained a slightly higher accuracy (0.973) and Youden index (0.952) compared to the best values achieved by the four clinicians. In addition, the speed of our DL algorithm was 15.2 ± 0.3 s/40 cases, much faster than the inference speeds of the clinicians, ranging from 177.2 ± 28.0 s/40 cases to 241.2 ± 64.1 s/40 cases.

CONCLUSIONS

Our algorithm demonstrated comparable or even better performance compared to clinicians in assessing spine growth potential. This stable, efficient, and convenient algorithm seems to be a promising approach to assist doctors in clinical practice and deserves further study.

CLINICAL RELEVANCE STATEMENT

This method has the ability to quickly ascertain the spine growth potential based on EOS radiographs, and it holds promise to provide assistance to busy doctors in certain clinical scenarios.

KEY POINTS

• In the clinic, there is no available computer-based method that can automatically assess spine growth potential. • We developed a deep learning-based method that could automatically ascertain spine growth potential. • Compared with the results of the clinicians, our algorithm got comparable results.

Quantitative Skeletal Imaging and Image-Based Modeling in Pediatric Orthopaedics

PURPOSE OF REVIEW

Musculoskeletal imaging serves a critical role in clinical care and orthopaedic research. Image-based modeling is also gaining traction as a useful tool in understanding skeletal morphology and mechanics. However, there are fewer studies on advanced imaging and modeling in pediatric populations. The purpose of this review is to provide an overview of recent literature on skeletal imaging modalities and modeling techniques with a special emphasis on current and future uses in pediatric research and clinical care.

RECENT FINDINGS

While many principles of imaging and 3D modeling are relevant across the lifespan, there are special considerations for pediatric musculoskeletal imaging and fewer studies of 3D skeletal modeling in pediatric populations. Improved understanding of bone morphology and growth during childhood in healthy and pathologic patients may provide new insight into the pathophysiology of pediatric-onset skeletal diseases and the biomechanics of bone development. Clinical translation of 3D modeling tools developed in orthopaedic research is limited by the requirement for manual image segmentation and the resources needed for segmentation, modeling, and analysis. This paper highlights the current and future uses of common musculoskeletal imaging modalities and 3D modeling techniques in pediatric orthopaedic clinical care and research.

The tibial tubercle-trochlear groove distance: a comparison study between EOS and MRI in the paediatric population

OBJECTIVE

This study aims to compare the relative reliability and accuracy of TT-TG measurements in EOS with that of MRI in a paediatric population.

METHODS

Patients were included if they underwent both an MRI and EOS scans and were under the age of 16. Two authors recorded the TT-TG distances on each modality at two separate time points. In the EOS images, the distance between the two points was measured in the horizontal 2D plane. In the MRI images, it was done in the plane referenced by posterior femoral condylar axis. The intra- and inter-rater reliability was assessed in each modality and between modalities.

RESULTS

Twenty-seven patients (30 knees), 14 males, and 13 females with an average age of 13 years (range: 7-16 years) were included in the study. The mean TT-TG distance on EOS scan and MRI scan was 14 mm. On inter- and intra-observer analysis, both imaging modalities had excellent reliability (0.97 ICC for EOS and 0.98 ICC for MRI inter-observer) and repeatability (0.98-0.99 ICC for EOS and 0.99 ICC for MRI for intra-observer). However, on comparing the two imaging modalities (EOS vs MRI), the ICC was fair (0.56 ICC for rater 1 and 0.65 ICC for rater 2).

CONCLUSION

While the EOS TT-TG measurements were precise and reproducible, they were only moderately comparable to MRI TT-TG measurements. Consequently, EOS TT-TG measurements should not be used for decision-making without the development of EOS-specific TT-TG values that indicate the need for distal realignment surgery.

LEVEL OF EVIDENCE

Level II.

Changes in Parameters after High Tibial Osteotomy: Comparison of EOS System and Computed Tomographic Analysis

Unintended rotation of the distal tibia occurs during medial open-wedge high tibial osteotomy (MOWHTO). Computed tomography (CT) is the standard method of measuring lower limb alignment; however, the new low-dose EOS system allows three-dimensional limb modeling with automated measurements of lower limb alignment. This study investigated the differences between the changes in lower limb alignment profiles obtained using the EOS system and CT in patients who underwent MOWHTO. We investigated whether any factors contributed to the degree of deformation. Thirty patients were prospectively enrolled between October 2019 and February 2023. Changes in femoral and tibial torsion, femorotibial rotation, and posterior tibial slope were measured using pre- and post-MOWHTO CT and EOS images. We found no significant difference in pre- and postoperative tibial torsion or posterior tibial slope between CT and EOS. No variables showed a significant correlation with changes in the tibial torsion or posterior tibial slope. This study confirmed the possibility that the EOS system could replace CT in measuring changes in several parameters pre- and postoperatively. Furthermore, we confirmed that the distal tibia tended to be internally rotated after MOWHTO; however, we found no significantly related parameters related to deformation caused by MOWHTO.