Axis In Sagittal Plane Research Articles

Clinical three-dimensional anatomy of the femur considering navigation-aided surgery of total knee arthroplasty in Japanese patients

PurposeFew studies exist regarding sagittal alignment describing femur morphology in navigation-aided surgery. This study investigated the three-dimensional (3D) sagittal femoral alignment of the whole femur. MethodsSeventy-three consecutive patients (59 females, 14 males, mean age: 76.1 years), yielding 140 femurs, were included in this study. A computed-tomography-based patient-specific 3D femur model was used to define a mechanical axis-based reference plane. Proximal and distal femoral axis angles (PFA, DFA) to the reference plane were measured in 3D using custom software. PFA and DFA represent the proximal and distal inclination of the femoral anatomical axis in sagittal plane, respectively. ResultsPFA (10.6 ± 1.5°) was greater than DFA (2.6 ± 1.6°; P < 0.0001). DFA in females (2.3 ± 1.4°) was smaller than in males (3.9 ± 1.7°; P < 0.0001). ConclusionThis is the first report of measurement of femoral sagittal alignment related to both 3D anatomy and decision making of femoral flexion angle using navigation surgery for total knee arthroplasty. This report shows a robust DFA measurement that could be used as a template for femoral implants flexion angle when performing both conventional and navigated total knee arthroplasty.

Femur deformity correction planning in sagittal plane using mechanical axis

Recently, deformity correction planning using reference lines and angles is a standard procedure. At the same time, both anatomical and mechanical axes are used for the frontal plane. However, until nowadays, there was no algorithm for planning femoral deformity correction in the sagittal plane based on the mechanical axes of the bone fragments. The aim of this study was to develop a method of femur deformity correction planning in the sagittal plane based on mechanical axes. Materials and Methods: On the basis of computer tomography data of 23 adults with nondeformed femurs, we measured the angular relationships between the anatomical axis of the proximal femur in sagittal plane and mechanical axis (∠maj) and the angular relationships between the femoral neck axis and mechanical axis in sagittal plane (∠laj). Results: It was found that ∠maj was 16.0° ±7.6°, and ∠laj was 10.2° ±2.4°. Based on the data obtained, we developed a method for planning the correction of femoral deformities in the sagittal plane. According to this method, the mechanical axis of the proximal bone fragment can be determined using any of three options: (1) “Joint line based.” In this method, the proximal joint line of the femur is drawn, then from the center of the femur head with the angle 85° (mean value of mPPFA) to this line is drawn a line that is mechanical axis; (2) “Femoral neck based.” The neck axis is drawn first, then from the center of the femur head with the angle 16° (mean value ∠maj) to this line is drawn a line that is mechanical axis; and (3) “Anatomical axis based.” First, the anatomical axis of the proximal femur is drawn, then a line parallel to the anatomical axis from the center of the femoral head is drawn, then a line at an angle of 10° (mean value ∠laj) to it is drawn, that is the mechanical axis. Determination of the mechanical axis of the distal fragment in sagittal plane is made by the following: the distal joint line is drawn and divided into five equal segments. Then, the point located on the border of the front 2/5 and the rear 3/5 of the segment is found. From that point, at an angle of 81° (mean mPDFA), a mechanical axis of the distal femur fragment is drawn. The intersection of the mechanical axes of the proximal and distal fragments defines the apex of the deformity. Conclusion: The proposed method for planning deformity correction based on mechanical axes for the sagittal plane complements the existing planning methods for the frontal plane and improves the quality, namely the accuracy of preoperative planning.

The geometrical axis of the talocrural joint—Suggestions for a new measurement of the talocrural joint axis

BackgroundDespite intensive research there is no consensus about the talocrural joint axis. The aim of the present study is a new method to determinate the geometric rotational axis of the talocrural joint. MethodsWe analyzed 98 CT-scans of full cadaver Caucasian legs. We generated three-dimensional reconstruction models of the talus. A best fitting cone was orientated to the talar articular surface. The geometric rotational axis was defined to be the axis of this cone. ResultsThe geometric rotational axis of the talocrural joint is orientated from lateral–distal to medial–proximal (85.6°±10 compared to anatomical tibial axis in torsional plane), from posterior–distal to anterior–proximal (81.43°±44.35 compared to anatomical tibial axis in sagittal plane) and from posterior–medial to anterior–lateral (169.2°±5.91 compared to intermalleolar axis in axial plane). ConclusionsThe consideration of our results might be helpful for better understanding of ankle biomechanics.

Three-dimensional Analysis of the Talocrural Joint Axis

Category: Ankle Introduction/Purpose: The total ankle replacement (TAR) is increasingly used in cases of severe ankle arthritis. Although the knowledge about joint kinematics is crucial for designing and positioning of TAR there is no consensus about the talocrural joint axis. The aim of the present study was the determination of the kinematic rotational axis of the talocrural joint as an orientation for prosthesis positioning. Methods: We analyzed 96 CT-scans of full cadaver caucasien legs. With the software Mimic, 3-Matic (both Materialize) and GOM inspect we generated three-dimensional reconstruction models of the talus and a best fitting cone orientated to the talar articular surface. The kinematic rotational axis was defined to be the axis of this cone. Results: The determination of the kinematic rotational axis showed a high inter- and intrarater reliability. The kinematic rotational axis of the talocrural joint is orientated from lateral-distal to medial-proximal (84.9° ± 8.5 compared to mechanical tibial axis in frontal plane), from dorsal-proximal to anterior-distal (93.1° ± 42.3 compared to mechanical tibial axis in sagittal plane) and from dorsal-lateral to anterior-medial (169.0° ± 6.7 compared to mechanical tibial axis in axial plane). A high standard deviation especially in the sagittal plane was noteworthy. Conclusion: With the present study we present a new reproducable single-axis model of the talocrural joint. Our data showed relevant interindividual variations. The consideration of these variations might support the development of patient-specific TAR implantation techniques.

The Ipsilateral Adjacent Laminae

A retrospective radiographic analysis and applied anatomical study. The aim of this study was to evaluate the relationships between the ipsilateral lamina/laminae and pedicle axis in the sagittal plane, and the feasibility of free hand pedicle screw placement in subaxial cervical spine without intraoperative fluoroscopic guidance. The morphology of subaxial cervical spine pedicle has been studied extensively. However, to our knowledge, no study has specifically evaluated the relationships between the ipsilateral lamina/laminae and pedicle axis in the sagittal plane on computed tomography (CT) reconstruction images. Axial CT images of 70 adult cases were obtained. Multi-directional pedicle axis reconstruction images of subaxial cervical spines were analyzed. Both the angle formed by the direction of ipsilateral lamina to the pedicle axis in the oblique sagittal plane (lamina-pedicle angle, LPA) and the angle formed by the tangential line passing the ipsilateral adjacent outer laminae cortex to the pedicle axis in the oblique sagittal plane (tangential line pedicle angle, TPA) were recorded. On the basis of the radiographic data, a "T"-shaped guiding tool was designed, and the accuracy of free hand subaxial pedicle screw placement using the guiding tool was evaluated in 12 cadavers. A total of 350 vertebrae were analyzed. Averaged LPA ranged from 72.2 degrees at C3 to 84.2 degrees at C6, averaged TPA ranged from 89.8 degrees at C3 to 90.7 degrees at C6. The TPA showed a high level of consistency close to a right angle. A total of 115 inserted subaxial cervical pedicle screws on 12 cadavers were evaluated. The rate of screw insertion without pedicle wall penetration was 98%, and the rate of pedicle wall penetration of more than 2 mm in the sagittal plane was 0%. The TPA serves to be a reliable guide in determining the direction of subaxial cervical pedicle axis in the sagittal plane. Free hand placement of subaxial pedicle screw is feasible under the guidance of the newly designed guiding tool based on TPA. 5.

On Unsatisfactory Outcomesof Transpedicular Fixation

Objective. The analysis of structure and frequency of unsatisfactory outcomes occurring after transpedicular spinal fusion. Material and Methods. The results of spinal fusion with internal transpedicular constructions in 96 patients with uncomplicated fractures in the lower thoracic and lumbar spine were assessed. Results. The following unsatisfactory outcomes were revealed within 1 to 5 years after surgery: breakage of rods – 9 cases, surface soft tissue inflammation – 3, screw misplacement outside anatomical landmarks – 2, kyphotic deformity, changing spinal axis in sagittal plane – 2, preservation of preoperative vertebral wedging after removal of the construction – 7 cases. Сonclusion. Complex systemic prevention of unsatisfactory outcomes and optimization of preoperative stage allow improving treatment results in patients with uncomplicated fractures of lower thoracic and lumbar vertebra.

Bony Landmarks for Determining the Mechanical Axis of the Femur in the Sagittal Plane during Total Knee Arthroplasty

BackgroundThere is no accepted landmark for the mechanical axis of the femoral axis in sagittal plane in conventional total knee arthroplasty.MethodsAs palpable anatomic landmarks of the femur, lateral epicondyle, and anterior margin of the greater trochanter were identified. The line connecting these two landmarks was defined as the "palpable sagittal axis". The mechanical axis of the femur was compared with the palpable sagittal axis and the distal femoral anterior cortex axis. These axes were also compared with sagittal bowing of the femur.ResultsThe distal femoral anterior cortex axis and the palpable sagittal axis were flexed by 4.1° and 2.4° more than the sagittal mechanical axes, respectively (p < 0.05). However, the palpable sagittal axis was not correlated with sagittal bowing of the femur (Spearman's rs, 0.17; p = 0.14).ConclusionsThe palpable sagittal axis showed a consistent relationship with the sagittal mechanical femoral axes regardless of the severity of the sagittal bowing of the femur.