Location of the ankle center for total knee arthroplasty

Computed tomography-based morphometric analysis of normal distal tibiofibular syndesmosis in the Indian population

BACKGROUND

In suspected Ankle Instability, the parameters that can be defined in the X-ray have their limitation owing to their variability in positioning and rotation of the tibiofibular joint. This inaccuracy further increases due to variability in morphometric parameters of distal tibiofibular syndesmosis among different populations based on race and sex. This research aims to study morphometry of normal distal tibiofibular syndesmosis based on computed tomography imaging in the Indian population.

METHODS

An Prospective observational study was performed from December 2020 to October 2022 on normal ankle CT scans of 100 Indian population using axial, sagittal, and coronal CT images. Anterior and posterior tibiofibular distance, Morphology of the incisura fibularis based on depth, Tibiofibular clear space (TFCS) and tibiofibular overlap (TFO), Transverse and longitudinal length of the fibula, and Relationship between the center of the talus and the center of a line joining the outer aspect of malleoli in the coronal plane were measured and analyzed by two different observers.

RESULTS

Out of the 100 participants, 77 (77 %) were male, and 23 (23 %) were female. The overall mean age of participants was 34.69 ± 9.7 years. The incisura fibularis was concave in 54 %, and shallow in 46 %. Anterior tibiofibular distance, Posterior tibiofibular distance, and Tibiofibular overlap were significantly different in comparison to the male with female populations (p-value < 0.05).

CONCLUSION

This study gives the indices that describe normal variations in the anatomical relationship between the fibula and fibular incisure in the Indian population, which will be helpful for improving the diagnostic accuracy of distal tibiofibular syndesmoses and providing optimal treatment in order to improve functional outcomes and reduce the risk of complications.

LEVEL OF EVIDENCE

III.

Combined femoral and tibial component total knee arthroplasty device rotation measurement is reliable and predicts clinical outcome

BACKGROUND

The optimal total knee arthroplasty (TKA) rotational alignment and how best to obtain and measure it are debatable. The aim was to analyse the reliability of the Berger femoral, three different tibial and four different combined two-dimensional computer tomography (2D-CT) TKA component rotation measurements, and to ascertain which rotational values best predict a successful clinical outcome.

METHODS

The 2D-CT scans were obtained post-operatively on 60 patients who had TKA. We determined one femoral [Berger's femoral angle (BFA)], three tibial [Berger's tibial angle (BTA), anatomical tibial angle (ATA) and bimalleolar posterior tibial component angle (BM_PTCA)] and four combined [transepicondylar posterior tibial component angle (TE_PTCA), bicondylar posterior tibial component angle (BC_PTCA, transepicondylar bimalleolar angle (TE_BM) and bicondylar bimalleolar angle (BC_BM)] TKA rotation angles. We made all measures in 23 patients twice by three observers and determined inter- and intra-observer agreement using the Bland-Altman plot method. We analysed measures of 55 patients using the area under the ROC curve (AUC) analysis to ascertain the discriminative capacity of BFA, ATA, TE_PTCA and BC_PTCA for predicting a successful clinical outcome according to the Knee Society Score (KSS) threshold.

RESULTS

ATA showed the smaller inter- and intra-observer average of differences (-0.1° and 1.6°, respectively) of the studied methods followed by BFA (-0.9° and 1.4°), TE_PTCA (-2.1° and 2.7°) and BC_PTCA (-0.5° and 1.8°). BFA (-4° to 2.1° and -6.1° to 8.8°) and BC_PTCA (-4.4° to 3.4° and -7.9° to 4.4°) showed the narrower inter- and intra-observer limits of agreement. A TKA device rotation (BC_PTCA) < 0.8° of external rotation (ER) predicted a KSS and KSS knee successful outcome, and < 3.8° ER for KSS functional (AUC = 0.889; 0.907 and 0.764, respectively). BFA and ATA < 0.9° ER and < 3.9° internal rotation (IR) predicted a successful KSS knee outcome (AUC = 0.796 and 0.889, respectively).

CONCLUSION

The ATA tibial component rotation measurement was the most reliable of those studied. BFA, TE_PTCA and BC_PTCA were reliable measures for TKA femoral and combined rotation. The presence of a minimal rotation between the TKA components (BC_PTCA) and a small femoral ER or tibial IR predicted a successful KSS outcome.

LEVEL OF EVIDENCE II

Accuracy of intraoperative bone registration and stereotactic boundary reconstruction during total knee arthroplasty surgery

BACKGROUND

The intraoperative registration of the bones play a crucial role in image-based computer-assisted knee arthroplasty to achieve accurate implant placement and to create reliable stereotactic bone boundaries for robot-assisted surgical systems.

METHOD

This study assessed the intraoperative registration accuracy on six intact fresh frozen cadavers.

RESULTS

Rotational errors around the mechanical axis were the largest, with a standard deviation of 1.2° and outliers up to 3.7°. The mean translational errors were lower than 1 mm, with outliers up to 1.5 mm. These errors were amplified to 2 mm for the registration-based reconstruction of the posterior bone surface at the resection levels.

CONCLUSION

Given the cumulative behaviour of surgical errors, registration errors can affect the final implant positioning. Furthermore, inaccuracies in the reconstructed bone boundary directly affect the virtual stereotactic boundaries used in robotic-assisted surgery and can result in an incomplete resection or inadvertent soft tissue damage.

Comparison of tibial alignment parameters based on clinically relevant anatomical landmarks : a deep learning radiological analysis

AIMS

Accurate identification of the ankle joint centre is critical for estimating tibial coronal alignment in total knee arthroplasty (TKA). The purpose of the current study was to leverage artificial intelligence (AI) to determine the accuracy and effect of using different radiological anatomical landmarks to quantify mechanical alignment in relation to a traditionally defined radiological ankle centre.

METHODS

Patients with full-limb radiographs from the Osteoarthritis Initiative were included. A sub-cohort of 250 radiographs were annotated for landmarks relevant to knee alignment and used to train a deep learning (U-Net) workflow for angle calculation on the entire database. The radiological ankle centre was defined as the midpoint of the superior talus edge/tibial plafond. Knee alignment (hip-knee-ankle angle) was compared against 1) midpoint of the most prominent malleoli points, 2) midpoint of the soft-tissue overlying malleoli, and 3) midpoint of the soft-tissue sulcus above the malleoli.

RESULTS

A total of 932 bilateral full-limb radiographs (1,864 knees) were measured at a rate of 20.63 seconds/image. The knee alignment using the radiological ankle centre was accurate against ground truth radiologist measurements (inter-class correlation coefficient (ICC) = 0.99 (0.98 to 0.99)). Compared to the radiological ankle centre, the mean midpoint of the malleoli was 2.3 mm (SD 1.3) lateral and 5.2 mm (SD 2.4) distal, shifting alignment by 0.34^o (SD 2.4^o) valgus, whereas the midpoint of the soft-tissue sulcus was 4.69 mm (SD 3.55) lateral and 32.4 mm (SD 12.4) proximal, shifting alignment by 0.65^o (SD 0.55^o) valgus. On the intermalleolar line, measuring a point at 46% (SD 2%) of the intermalleolar width from the medial malleoli (2.38 mm medial adjustment from midpoint) resulted in knee alignment identical to using the radiological ankle centre.

CONCLUSION

The current study leveraged AI to create a consistent and objective model that can estimate patient-specific adjustments necessary for optimal landmark usage in extramedullary and computer-guided navigation for tibial coronal alignment to match radiological planning.Cite this article: Bone Jt Open 2022;3(10):767-776.

Efficacy Analysis of Selection of Distal Reference Point for Tibial Coronal Plane Osteotomy during Total Knee Arthroplasty: A Literature Review

Total knee arthroplasty is an effective treatment for end-stage knee osteoarthritis. The tibial platform osteotomy must take full account of the coronal plane, the sagittal plane, and the rotational alignment of the tibial prosthesis. During surgery, individual differences in the coronal alignment of the tibia need to be taken into account as poor alignment after surgery can lead to rapid wear of the tibial platform, reducing the longevity of the prosthesis and adversely affecting quality of life. Intraoperative tibial osteotomies are often performed using extramedullary alignment. When an extramedullary alignment approach is used, the proximal tibial osteotomy guide is usually placed in the medial third of the tibial tuberosity. There is no consensus on the most reliable anatomical landmarks or axes for achieving distal tibial coronary alignment. Anatomical points or reference axes that are highly reproducible and precise need to be identified. From available data it appears that most surgeons use the extensor hallucis longus tendon, the second metatarsal, and the anterior tibial cortex to determine the distal localization point. However, its accuracy has not been confirmed in clinical and radiographic data, and the alignment concept and preoperative planning for total knee arthroplasty has paid more attention to rotational alignment, but there are few studies on the coronal alignment of the tibia. This article reviews the recent use of the distal tibial coronal osteotomy reference point in total knee arthroplasty. However, due to there being only a small number of studies available, the evidence collected is insufficient to prove that a certain reference axis has obvious advantages and a combination of different reference points is needed to achieve the ideal lower extremity force line angle.