Restoration Of Mechanical Alignment Research Articles

1064 Extra-Articular Tibial Deformity Management in Total Knee Replacement

Abstract Aim In knee replacements, restoration of mechanical alignment is essential. Patients with extra-articular deformities (EAD) pose challenges in planning knee replacements. We present a method, based on our experience and review of literature on planning knee replacement surgery, in the presence of extra-articular coronal plane deformity of the tibia. Method Retrospective analysis was made of six patients with EAD of the tibia who underwent knee replacement at our centre. Mechanical axis of the tibia is considered and positioning of the tibia component is planned perpendicular to the mechanical axis of the tibia. The integrity of the collaterals determines the need for correction. Tibial resection >15mm from medial or lateral aspect of the tibia is an indication for corrective osteotomy prior to replacement surgery. The hip knee ankle angle (HKA) was noted. Pre-operative, post-operative clinical score, degree of constraints and post-operative complications were recorded. A post-operative long leg alignment radiograph was obtained. Result All patients had total knee replacement without correction of deformity. Adequate alignment of the limb and restoration of mechanical axis was achieved in all six patients without the need for correction of tibial deformity. All patients had improvement in their HKA angle and Oxford knee score. No re-operations were required, and no complications recorded. Conclusions Our study will help provide guidance on operative planning and decisions making for patients with extra-articular coronal plane tibial deformities.

Robotic arm assisted total knee arthroplasty workflow optimization, operative times and learning curve

Robotic arm assisted total knee arthroplasty (RTKA) has many potential benefits including advanced preoperative templating, restoration of mechanical alignment, accuracy of bony resection, robust safety mechanisms, and dynamic gap balancing. One of the most frequently quoted drawbacks preventing experienced surgeons from adopting this technology is the perceived increase in surgical time. This technique paper outlines the general concepts used to improve operating room efficiency as well as the step-by-step workflow to consistently perform RTKA with surgical times under 60 minutes. Although the clinical and functional results of RTKA are just beginning to be described in literature, this manuscript demonstrates that with proper technique and workflow, surgical time should not be a significant factor to deter surgeons from adopting this new technology.

Total Knee Arthroplasty in Patients With Extra-Articular Deformity: Restoration of Mechanical Alignment Using Accelerometer-Based Navigation System

BackgroundTotal knee arthroplasty (TKA) in patients with post-traumatic extra-articular deformity (EAD) is difficult to manage using conventional instrumentation techniques. In this study, we evaluate whether accelerometer navigation system can be a valuable option to make accurate bone resections and restore the neutral mechanical axis in complex TKA patients with EAD. MethodsFrom May 2015 to June 2017, 18 consecutive TKA were performed in 18 patients with knee osteoarthritis with associated EAD. An accelerometer-based navigation system was used to guide tibial and femoral resection in the coronal and sagittal plane. Postoperative lower limb alignment in coronal plane and component position in coronal and sagittal plane was measured through full-leg weight-bearing X-ray. Clinical score were recorded using the Knee Society Score at the final follow-up. ResultsThe mean hip-knee-ankle angle was 0.9° ± 1.4° varus alignment. The coronal alignment of the femoral component was 89.2° ± 1.9°, and the coronal alignment of the tibial component was 89.4° ± 2.1°. The sagittal alignment of the femoral component was 93.2°± 1.9°, and the sagittal alignment of the tibial component was 84.4° ± 3.1°. At the final follow-up, the Knee Society Score was 89 points (range, 82-100), and the functional score was 86.7 points (range, 60-100). No intraoperative and postoperative surgical complications were reported using this technology. ConclusionAccelerometer-based navigation is accurate in achieving neutral mechanical alignment and optimal implant position after TKA in patients with EAD. This system should be considered a valuable option to the more complex technique of computer navigation or robotic surgery.

Evolution of customization design for total knee arthroplasty

Total Knee Arthroplasty (TKA) is a highly successful surgical procedure with more than 600,000 TKA's performed annually in the US. Interest in improving surgical outcomes has led to improvements in surgical technique, instrumentation, and implant design. Computer navigation and robotic systems were introduced to further refine the mechanical alignment of joint replacement procedures. The cost to implement some of these technologies and the additional time required in the operating room to utilize these developments has limited the acceptance of them broadly. The introduction of custom instrumentation and cutting blocks based on computed tomography (CT) or magnetic resonance imaging (MRI) has allowed for better restoration of mechanical alignment. Unfortunately, little has changed in patient satisfaction in the past ten years. The recent introduction of patient specific instrumentation and patient specific implants is another step forward to restore the pre-deformity anatomy and joint geometry. This new technology can benefit the hospital by improving operating room time efficiencies through having shorter set-up times, and the elimination of cleaning, sterilization and inventory costs. The patient can potentially benefit by a shorter operative time, improved postoperative alignment and better fitting implants.

Metal-reinforced Cement Augmentation for Complex Talar Subsidence in Failed Total Ankle Arthroplasty

There are limited options for failed total ankle arthroplasty (TAA) with major talar bone loss and component subsidence. Surgical options for this condition include revision arthroplasty, salvage arthrodesis, or amputation. Revision arthroplasty generally has been considered in situations of loose components with minimal bone loss or use of expensive custom-fabricated prosthetic components with elongated stems. Historically, failure that involves major talar bone loss has been considered resistant to reconstruction, and responsive only to complex arthrodesis or amputation. In this report, we describe a unique method of restoring talar support and preserving ankle function after failed TAA with major talar bone loss and component subsidence. Talar reconstruction using metal-reinforced bone cement augmentation is combined with the Inbone (Wright Medical Technology, Inc., Arlington, TN) total ankle system to restore talar height and ligamentous support. This technique has been used successfully in the last 4 years for various patterns of talar bone loss and obviates the need for custom components. When successfully performed, the revision technique results in restoration of mechanical alignment, anatomic height, and component support, in addition to providing substantial symptomatic relief.

Correction of axial and rotational alignment after medial and lateral releases during balanced gap TKA

Background and purpose Restoration of mechanical alignment after total knee arthroplasty can be achieved with ligament releases. Several previously described sequences and results achieved with cadaver knees, with measured resection implantation techniques, may not be applied to the balanced gap technique. We investigated the peroperative effect of stepwise soft tissue releases following the “tightest structure first” on leg axis in extension and femur rotation in flexion.Methods During PCL-retaining total knee arthroplasty (TKA), using a balanced gap technique in 54 patients we determined the effect of each ligament release using a navigation system while the knee was distracted with a tensor in extension and flexion. The effect on alignment in extension and on femoral rotation in flexion was measured for each release separately.Results In more than half of the patients, one or more ligament releases were necessary. Release of the posteromedial condyle led to a minor effect on leg axis in extension and femoral rotation in flexion, release of the superficial medial collateral ligament to a few degrees, mainly in extension. Release of the iliotibial tract led to a small correction of leg alignment in extension. There was no statistically significant difference in the alignment-correcting effect of a release dependent upon the sequence in which the structure was released.Interpretation In PCL-retaining TKA, a stepwise “tightest structure first” protocol for ligament releases in extension with the balanced gap technique results in effective, gradual, alignment correction in extension, and limited femoral rotating effects in flexion.