Poor accuracy of plain radiographic measurements of prosthetic migration and alignment in total ankle replacement

Development and validation of a clinical tool to semi-automatic measure three-dimensional TAR alignment on two-dimensional radiographs

BACKGROUND

Malalignment is often postulated as an important reason for the high failure rate of total ankle replacements (TARs). The correlation between TAR malalignment and clinical outcome, however, is not fully understood. Improving and expanding radiographic TAR alignment measurements in the clinic might lead to a better insight into the correlation between malalignment and the clinical outcome. This study aims to develop and validate a tool to semi-automatic measure TAR alignment, and to improve alignment measurements on radiographs in the clinic.

METHODS

A tool to semi-automatically measure TAR alignment on anteroposterior and lateral radiographs was developed in MATLAB. Using the principle of edge contouring and the perpendicular relationship between the anteroposterior and lateral radiographs, the exact configuration of the TAR components can be found. Two observers validated the tool by measuring TAR alignment of ten patients using the tool. The Intraclass Coefficient (ICC) was calculated to assess the reliability of the developed method. The results obtained by the tool were compared to clinical results during radiographic follow-up in the past, and the accuracy of both methods was calculated using three-dimensional CT data.

RESULTS

The tool showed an accuracy of 76% compared to 71% for the method used during follow-up. ICC values were 0.94 (p < 0.01) and higher for both inter-and intra-observer reliability.

CONCLUSIONS

The tool presents a reproducible method to measure TAR alignment parameters. Three-dimensional alignment parameters are obtained from two-dimensional radiographs, and as the tool can be applied to most TAR designs, it offers a valuable addition in the clinic and for research purposes.

Corin ankle arthroplasty: Case-series

BACKGROUND

Total Ankle Arthroplasty (TAA) is complex and can bring a wide variety of complications. Implant revision rates can vary from 4% to 8% in 5 years. Recent publications have shown good results in the short and intermediate follow-up and high patient satisfaction. The pre- and postoperative evaluation of these patients should include physical examination and objective radiographic measurements, which may have predictive value for implant failures and survivorship. In this paper we will present the results obtained with 29 patients treated with the Zennith (Corin Group, UK) total ankle prosthesis in Brazil.

METHODS

This paper presents the results obtained with 29 patients treated with the Corin-Zennith prosthesis in three tertiary hospitals in Brazil, with an average follow-up of 5 years. The patients were submitted to clinical and radiographic evaluation. There were seventeen women and twelve men, ranging in age from 35 to 76 years, who were submitted to surgical treatment between January 16, 2013 and May 5, 2017.

RESULTS

Seven patients (24%) presented cysts, being 4 (13.7%) tibial cysts and 3 (10.3%) tibial and talar cysts. Six patients (20.6%) presented talar subsidence and 3 (10.3%) presented tibial subsidence. Three patients (10.3%) presented component wear. VAS reduced and AOFAS and ROM increased in the post-operative period. The development of Cysts was associated with the theta angle and the difference in LTS (between the post and preoperative period) was associated with tibial subsidence. The complications rate was 44.8%, the revision rate was 6.9% and the survivorship rate was 93.1%.

CONCLUSION

The Corin-Zennith prosthesis demonstrated to be a safe implant for improving functional parameters. Functional outcomes were not influenced for most commonly measured radiographic parameters. Further studies are needed to better understand these associations.

Tarsometatarsal bone remodelling after subtalar arthroereisis

PURPOSE

Subtalar arthroereisis has been described for the treatment of flexible juvenile flatfoot. However, the mechanism responsible for deformity correction has not yet been investigated adequately. The aim of this study was to document the effect of subtalar arthroereisis on the tarsometatarsal bone morphology.

METHODS

We retrospectively reviewed the clinical and radiological data of 26 patients (45 feet) with juvenile flexible flatfoot deformity treated by subtalar arthroereisis at our department between 2000 and 2018. Radiological evaluation included angular measurements of tarsometatarsal bone morphology as well as hindfoot and midfoot alignment. Mean radiographic follow-up was 19.4 months (sd 8.8; 12 to 41).

RESULTS

A significant change of angular measurements of tarsometatarsal bone morphology was found after subtalar arthroereisis (p < 0.001). While there was an increase of the distal medial cuneiform angle (DMCA) and the medial cuneo-first metatarsal angle on the anteroposterior view, a decrease of the naviculo-medial cuneiform angle and the medial cuneo-first metatarsal angle was seen on the lateral view. Furthermore, we found significant improvements of all hindfoot and midfoot alignment parameters except the lateral tibio-calcaneal angle and the calcaneal pitch angle (p < 0.001).

CONCLUSION

Our data support the theory of tarsometatarsal bone remodelling, which may contribute to the effect of subtalar arthroereisis for the treatment of flexible juvenile flatfoot.

LEVEL OF EVIDENCE

IV.

Biomechanical Evaluation of the Accuracy in Radiographic Assessment of Femoral Component Migration Measurement after Total Hip Arthroplasty

INTRODUCTION

Implant subsidence is one criteria utilized to monitor for prosthesis loosening after total hip arthroplasty (THA) with initial implant subsidence assessment often done utilizing plain radiographs. The specific aim of this study was to identify the most reliable references when using plain radiographs to establish an image magnification with the goals being easy to use, inexpensive, reliable, and accurate.

METHODS

Two femoral stem implants (stem lengths: 127 mm, 207 mm) were utilized to simulate hemiarthroplasty of the hip with composite femurs. Different combinations of femoral stem distances from the radiographic film (ODD), source-detector differences (SDD), hip rotation, and hip flexion were elected. Standardized anterior-posterior pelvis for each parameter combination setup were taken. Radiographic measurements (head diameter, stem length, stem seating length) were undertaken five times by three examiners. Radiographic image magnification factors were generated from two references (head diameter and stem length). Radiograph measurement reproducibility and stem seating length errors using these magnification factors were evaluated.

RESULTS

High level of repeated measurements reliability was found for head diameter (99 ± 0%) and stem length (90 ± 7%) measurements, whereas seating length measurements were less reliable (76 ± 6%). Stem length error using the femoral head magnification factor yielded 11% accuracy. Stem seating length error using both magnification factors were not reliable (< 7% accuracy). All parameters, except SDD, showed significant effect on calibrated measurement error.

CONCLUSION

Current methods of assessing the implant subsidence after THA are inaccurate and unreliable. Clinicians should recognize these limitations and be cautious when diagnosing implant stability using plain radiographs alone.

Is Plain Anterior-Posterior Radiograph of the Pelvis Adequate for Assessment of Radiographic Implant Migration Evaluation in Total Hip Arthroplasty?

INTRODUCTION

A commonly utilized method of measuring femoral stem migration in total hip arthroplasty (THA) on plain anteroposterior (AP) pelvis radiograph with referenced image magnification has not been rigorously evaluated. This study aims to validate the reproducibility of the methods used in this technique.

METHODS

A retrospective study of the standardized AP pelvis radiographs of patients who had undergone THA utilizing a Corail® femoral stem was performed from June 2012 through December 2017. Radiological evaluation (head diameter, stem length, and stem seating length) were undertaken at three clinical follow-up times. Each radiographic measurement of each radiograph was repeated five times. Outcomes investigated included inter- and intra-radiograph reproducibility evaluation and radiographic image magnification. The stem length error and stem subsidence were also evaluated.

RESULTS

Two hundred THA patients met the inclusion/ exclusion criteria. The intra-radiograph reproducibility of the stem length and head diameter measurements have at least "good" reproducibility with repeated measurements falling within 0.5 mm for both measurements. The reliability for femoral stem seating length measurements has "questionable/poor" reproducibility. The inter-radiograph reproducibility was, however, substantially lower. High level of unreliable measurements with values less than 0.0 mm for both femoral stem length errors (55%) and femoral stem subsidence (32%) measurements. Less than 45% accuracy (femoral stem length error: 33%; femoral stem subsidence: 44%) to within 3 mm error.

CONCLUSIONS

This study demonstrates that the assessment of radiographic implant migration after THA made on a sequence of plain AP pelvis radiograph have poor reproducibility.Level of Evidence: III.

Reliability of hindfoot alignment measurements from standard radiographs using the methods of Meary and Saltzman

BACKGROUND

Few methods have been described for measuring hindfoot alignment from an anteroposterior view. The objective of this study was to compare two methods of angular measurement based on the views of Meary and Saltzman.

METHODS

Thirty asymptomatic volunteers were included. Four radiographs were performed: the views of Meary and Saltzman with parallel feet and with the Fick correction. The reproducibility was determined by the inter- and intraobserver variability (ICC).

RESULTS

Meary's method revealed a mean valgus angulation of 3.9° (SD 3.47°). The reliability was extremely variable with a mean ICC of 0.59. The best reproducibility was obtained with Meary's method with and without Fick correction.

CONCLUSION

The results of this study show that the reliability of the angular measurements depends on the radiographic view and measurement method chosen. The lateral Fick correction did not counteract the influence of tibial rotation. The same method should be used consistently.

SPECT/CT in Postoperative Foot and Ankle Pain

Postoperative pain is a clinically relevant issue in orthopedic patients, affecting more than 40% 1 year after foot and ankle surgery. Because of the very complex anatomy with many different joints and several motion axes, clinical examination and conventional imaging are sometimes not sufficient to identify a local pain generator. Local uptake of bone-seeking radiopharmaceuticals is known to correlate accurately with sites of pain generating foci and, thus, bone scintigraphy has been an established method to evaluate these respective patients for many years. However, the specificity is rather low if only planar images are acquired. The development of SPECT and especially of hybrid SPECT and CT imaging has significantly enhanced the specificity of this technique. The combination of both functional and morphological imaging, ideally performed with a dedicated SPECT/CT system to minimize misregistration owing to motion artifacts and to enhance image quality by attenuation correction, allows an early and reliable detection of pathologic bone processes, even in patients where radiological imaging with MRI or CT is hampered by metal implants. In diabetic patients with a neuropathic Charcot osteoarthropathy, infection can be differentiated from inflammatory bone alterations (causing bone marrow edema) almost certainly using SPECT/CT with radiolabeled white blood cells and antigranulocyte antibodies, allowing an individual and precise treatment planning either in the initial course of the disease or even after surgery. This article reviews the most frequent clinical challenges in patients after foot and ankle surgery, including a description of the various surgical procedures, the different imaging options with their advantages and disadvantages, and aims to integrate bone SPECT/CT into the clinical diagnostic workup.

Experience with Navigation in Total Ankle Arthroplasty. Is It Worth the Cost?

Optimal placement of correctly sized total ankle replacement (TAR) implants is elemental to prolonging the working life. The negative mechanical effects of implant malalignment are well characterized. There is one FDA-approved navigated TAR system with limited but encouraging outcomes data. Therefore, its value can be estimated only based on benefits other than a proven clinical outcomes improvement over conventional systems. These include unique preoperative planning through 3-dimensional templating and virtual surgery and the patient-specific cut guides, which also reduce overall instrumentation needed for the case. To better inform this conversation, well-observed longitudinal outcomes studies are warranted.

Reliability of the Radiographic Sagittal and Frontal Tibiotalar Alignment after Ankle Arthrodesis

Background

Accurate measurement of the tibiotalar alignment is important in radiographic outcome assessment of ankle arthrodesis (AA). In studies, various radiological methods have been used to measure the tibiotalar alignment leading to facultative misinterpretation of results. However, to our knowledge, no previous study has investigated the reliability of tibiotalar alignment measurement in AA. We aimed to investigate the reliability of four different methods of measurement of the frontal and sagittal tibiotalar alignment after AA, and to further clarify the most reliable method for determining the longitudinal axis of the tibia.

Methods

Thirty-eight weight bearing anterior to posterior and lateral ankle radiographs of thirty-seven patients who had undergone AA with a two screw fixation technique were selected. Three observers measured the frontal tibiotalar angle (FTTA) and the sagittal tibiotalar angle (STTA) using four different methods. The methods differed by the definition of the longitudinal tibial axis. Method A was defined by a line drawn along the lateral tibial border in anterior to posterior radiographs and along the posterior tibial border in lateral radiographs. Method B was defined by a line connecting two points in the middle of the proximal and the distal tibial shaft. Method C was drawn „freestyle”along the longitudinal axis of the tibia, and method D was defined by a line connecting the center of the tibial articular surface and a point in the middle of the proximal tibial shaft. Intra- and interobserver correlation coefficients (ICC) and repeated measurement ANOVA were calculated to assess measurement reliability and accuracy.

Results

All four methods showed excellent inter- and intraobserver reliability for the FTTA and the STTA. When the longitudinal tibial axis is defined by connecting two points in the middle of the proximal and the distal tibial shaft, the highest interobserver reliability for the FTTA (ICC: 0.980; CI 95%: 0.966–0.989) and for the STTA (ICC: 0.997; CI 95%: 0.996–0.999) is provided. Intergroup analysis for FTTA measurements revealed a statistically significant difference between the method in which the lateral border of the tibia was used to determine the longitudinal axis of the tibia, and the other methods in which the longitudinal axis was defined by bisecting the tibia.

Conclusions

When the longitudinal axis of the tibia is defined by connecting two points in the middle of the proximal and the distal tibial shaft for measuring the FTTA and STTA, the most favorable interobserver reliability is provided. Therefore, this method can be recommended for evaluating the frontal and the sagittal alignment on anterior to posterior and lateral radiographs after ankle arthrodesis.