Tibial Bone Cuts Research Articles

Effect of design and surgical parameters variations in mobile-bearing versus fixed-bearing unicompartmental knee arthroplasty: A finite element analysis.

Unicompartmental knee arthroplasty (UKAs) are available in the market as fixed- and mobile-bearing (FB and MB) and can be characterised by a different set of design parameters in terms of geometries, materials and surgical approaches, with overall good clinical outcomes. However, clear biomechanical evidence concerning the consequences of variations of these features on knee biomechanics is still lacking; therefore, the present study aims to perform a sensitivity analysis to see which outcomes are affected by these variations. For both MB-UKA and FB-UKA, five design and surgical parameters were defined (bearing insert thickness, tibial component material, implant components friction coefficient, antero-posterior slope angle and level of tibial bone resection). Two control models were defined based on standard configurations for both implants. Finite element analysis was chosen to perform this study, and different parameter combinations (216 models in total) were implemented and tested at both 0° and 90° of flexion, using a previously validated finite element knee model. The results were then evaluated in terms of bone and polyethylene Von Mises stress and tibio-femoral contact area. Bearing thickness, tibial bone cut and slope angle were found to be the most sensitive parameters for both types of UKAs. Specifically, changes in these parameters in the FB-UKA appeared to induce more significant variations in the polyethylene insert (both in terms of polyethylene stress and contact area), while in the MB-UKA, these changes influenced bone stress distribution more. Surgical parameters returned to have a more significant influence than material and friction variations; furthermore, the outcomes most affected by parameter variations were the insert-related ones for FB-UKA while for the MB-UKA were the ones regarding tibial bone stresses. Not Applicable.

A novel robotic surgical assistant for total knee arthroplasty has a learning curve ranging from 6 to 14 cases and exhibits high accuracy in tibial bone cuts

BackgroundThe adoption of robot-assisted total knee arthroplasty (TKA) aims to enhance the precision of implant positioning and limb alignment. Despite its benefits, the adoption of such technology is often accompanied by an initial learning curve, which may result in increased operative times. This study sought to determine the learning curve for the ROSA (Robotic Surgical Assistant) Knee System (Zimmer Biomet) in performing TKA and to evaluate the accuracy of the system in executing bone cuts and angles as planned. The hypothesis of this study was that cumulative experience with this robotic system would lead to reduced operative times. Additionally, the ROSA system demonstrated reliability in terms of the accuracy and reproducibility of bone cuts.MethodsIn this retrospective observational study, we examined 110 medical records from 95 patients who underwent ROSA-assisted TKA performed by three surgeons. We employed the cumulative summation methodology to assess the learning curves related to operative time. Furthermore, we evaluated the accuracy of the ROSA Knee System in performing TKA by comparing planned versus validated values for femoral and tibial bone cuts and angles.ResultsThe learning curve for the ROSA Knee System spanned 14, 14, and 6 cases for the respective surgeons, with operative times decreasing by 22 min upon reaching proficiency (70.8 vs. 48.9 min; p < 0.001). Significant discrepancies were observed between the average planned and validated cuts and angles for femoral bone cuts (0.4 degree ± 2.4 for femoral flexion, 0.1 degree ± 0.6 for femoral coronal alignment, 0.3 mm ± 1.2 for distal medial femoral resection, 1.4 mm ± 8.8 for distal lateral femoral resection) and hip–knee–ankle axis alignment (0.3 degree ± 1.9 )(p < 0.05) but not for tibial bone cuts. Differences between planned and validated measurements during the learning and proficiency phases were nonsignificant across all parameters, except for the femoral flexion angle (0.42 degree ± 0.8 vs. 0.44 degree ± 2.7) (p = 0.49).ConclusionThe ROSA Knee System can be integrated into surgical workflows after a modest learning curve of 6 to 14 cases. The system demonstrated high accuracy and reproducibility, particularly for tibial bone cuts. Acknowledging the learning curve associated with new robot-assisted TKA technologies is vital for their effective implementation.

The Use of Bone Hook in the Retrieval of Tibial Bony Cut. Technical Tip

Total ankle replacement, is technically demanding. Intraoperative malleolar fracture may result because of levering on the malleoli whilst removing the distal tibial cut. The technique described of using bone hook to retrieve the distal tibial bone cut is safe and easy.

Predicting postoperative coronal alignment after fixed-bearing unicompartmental knee arthroplasty using a new morphological assessment method: the arithmetic hip-knee-ankle angle

PurposeOnly a few reports have been published so far on factors that predict postoperative coronal alignment after unicompartmental knee arthroplasty (UKA). The purpose of this study is to clarify the relationship between the arithmetic hip-knee-ankle angle (aHKA) and postoperative coronal alignment after medial fixed-bearing UKA.MethodsOne hundred and one consecutive patients (125 knees) who underwent medial fixed-bearing UKA were assessed. Pre- and postoperative coronal HKA angles, lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and the thickness of the tibial and femoral bone cut were measured. aHKA was calculated as 180° − LDFA + MPTA. Correlations between postoperative HKA angle and aHKA, LDFA, and MPTA were investigated by single regression analysis. After the patients were divided into three groups according to the postoperative HKA angle, i.e., HKA angle > 180°, 175° < HKA angle ≤ 180°, and HKA angle ≤ 175°, aHKA, LDFA, MPTA, preoperative HKA angle, and the thickness of the distal femoral as well as tibial bone cut were compared among the three groups.ResultsaHKA and MPTA were positively correlated with postoperative HKA angle, while no correlation was found between postoperative HKA angle and LDFA. Among the three groups classified by postoperative HKA angle, significant differences were found in aHKA, MPTA, and preoperative HKA angle, while no significant difference was found in LDFA and the amount of distal femoral and tibial osteotomies.ConclusionsaHKA was correlated with postoperative HKA angle after medial fixed-bearing UKA, which was probably due to the influence of MPTA.

Improving alignment in total knee arthroplasty: a cadaveric assessment of a surgical navigation tool with computed tomography imaging

Purpose To investigate the accuracy of an imageless, optical surgical navigation tool to assist with femoral and tibial bone cuts performed during TKA. Patients and methods Six board-certified orthopedic surgeons participated in a laboratory cadaver investigation, performing femoral and tibial bone cuts with the assistance of a computer navigation tool. Femoral and tibial varus/valgus, tibial slope, femoral flexion, and both femoral and tibial rotation measurements from the device were compared with angular measurements calculated from computed tomography (CT) images of the knees. Results Measurements with the navigation tool were highly correlated with those obtained from CT scans in all three axes. For the distal femoral cut, the absolute mean difference in varus/valgus was 0.83° (SD 0.46°, r = 0.76), femoral flexion was 1.91° (SD 1.16°, r = 0.85), and femoral rotation was 1.29° (SD 1.01°, r = 0.88) relative to Whiteside’s line and 0.97° (SD 0.56°, r = 0.81) relative to the posterior condylar axis. For the tibia, the absolute mean difference in varus/valgus was 1.08° (SD 0.64°, r = 0.85), posterior slope was 2.78° (SD 1.40°, r = 0.60), and rotation relative to the anteroposterior axis (posterior cruciate ligament to the medial third of the tibial tuberosity) was 2.98° (SD 2.54°, r = 0.79). Conclusion Utilization of an imageless navigation tool may aid surgeons in accurately performing and monitoring femoral and tibial bone cuts, and implant rotation in TKA and thus, more accurately align TKA components.

Does measuring the medial gap before bone resection in total knee arthroplasty provide optimum gap adjustment and prevent bone recutting?

This study aimed to demonstrate that measuring the medial gap before bone resection during total knee arthroplasty (TKA) provides an optimum gap adjustment in varus knees. In this study, patients were separated into two groups. Group 1 included patients whose medial joint gap was measured before bone resection and Group 2 included patients who underwent conventional technique without measuring. The medial joint gap was measured with a custom-made gap measuring device up to the point that the knee was corrected and aligned along its mechanical axis. Medial joint gap distances, distal medial femoral bone cut thicknesses, amounts of tibial resection calculated; gap internal distances measured after cutting and the thicknesses of the trial inserts were recorded. A comparison was made between the groups concerning the number of patients requiring an additional tibial bone cut and the distribution of insert thicknesses. Extra tibial bone resections were performed in two (5.7%) patients in Group 1 and 10 (28.6%) patients in Group 2. In Group 1, where the medial joint gap was measured, the need for an additional bone resection was statistically less (p=0.018). In comparing the distribution of insert size by group, the number of patients on whom an 8 mm insert had been used was significantly greater in Group 1 (p=0.024). The findings obtained in this study suggest that measuring the medial joint gap before bone resection in total knee arthroplasty may prevent repeated bone recutting and additional bone resections.

Early Outcomes of Modified Technique of Mobile Bearing Unicondylar Knee Replacement.

Recent years have seen a resurgence in utilization of partial knee replacement. One such device frequently used is Oxford partial knee implant (OPK). Deeper tibial bone cut while performing OPK replacement may risk early failure. We prospectively looked at early outcomes of a modified technique (MT) of OPK replacement adopted by our centre to save tibial bone stock at 24months of follow up as compared to designer group described technique (DT) as a prospective cohort. At 2years follow up New Knee Society Score showed patient satisfaction (38.25 in DT vs 39.02 in MT, p value 0.10), objective (92.77 in DT vs 91.07 in MT, p value 0.21), expectation scores (14.77 in DT vs 14.85 in MT, p value 0.81) and activity (60.72 in DT vs 68.17 in MT, p value 0.79 were similar in MT group as compared to DT. The stair climbing ability (22.46 in MT vs 29.96 in DT, p value < 0.001) and getting up from chair (13.16 in MT vs 19.80 in DT, p value < 0.001), was better with MT group but most other patient performance scores were similar as assessed by DOP (Delaware Osteoarthritis Profile). Both groups had failure rate of 5% at 24months follow up. MT resulted in similar early outcomes in terms of patient reported outcomes, satisfaction and performance as compared to DT group. The MT to save tibial bone stock did not compromise early outcomes and can be utilised in certain patients with higher risk of tibial failure.

Bone Cut Accuracy in Total Knee Arthroplasty: Do Conventional Cutting Guides Stay True to the Planned Coronal Orientation of the Components?

Background: Total knee arthroplasty (TKA) has become the gold standard for the definitive treatment of knee osteoarthritis. One crucial aspect in the implantation of a TKA is the precise orientation of the femoral and tibial components. The main purpose of the present study is to assess, in patients undergoing total knee replacement, whether the difference between the planned angulation in the distal femoral cut and the angulation obtained in the postoperative radiological control is low enough to consider the conventional bone-cutting guides reliable. Methods: A retrospective study was designed with a consecutive series of patients who had undergone primary total knee arthroplasty using conventional instrumentation over one year. The authors analysed the main variable (bone cuts) while considering different variables (age, gender, surgeon, prosthesis, laterality, constraint, body mass index and alignment) to identify different patient patterns that justify the results in the main variable. Descriptive variables were analysed using the Mann–Whitney U and Kruskal–Wallis tests. Additionally, the correlation between continuous variables was explored in accordance with the Spearman correlation. Results: A total of 340 patients with a mean age of 75 ± 9.16 years were finally included in the present study. The mean absolute error of the main variable for the femoral coronal bone cut was 1.89° (SD 1.53). For the tibial coronal bone cut, it was 1.31° (SD 2.54). These values correspond to what remains after subtracting the radiological angulation obtained in the postoperative period from the planned intraoperative angulation of the distal femoral cut. No associations were observed between the main variable (the angulation of the proximal tibial cut and distal femoral cut) and the rest of variables for either the femur or tibia. Conclusion: A discrepancy between the planned angulation and the final radiological measure on the coronal plane of the femur and tibia using conventional cutting guides has been demonstrated. The degree of deviation is low enough that it probably does not affect clinical outcomes. Therefore, the use of conventional cutting guides will continue to be an appropriate tool to perform bone cuts in knee replacement surgery.

Independent of the preoperative coronal deformity, adjusted mechanical alignment leads in a high percentage to non-anatomical tibial and femoral bone cuts.

The technique of adjusted mechanical alignment (AMA) in total knee arthroplasty (TKA) has been described to achieve alignment and balancing goals in varus knees in a high percentage, albeit at the price of non-anatomical bone cuts. The purpose of this study was to analyze (1) whether AMA achieves similar alignment and balancing results in different types of deformity and (2) whether they can be achieved without altering the native anatomy. A series of 1000 patients with hip-knee-ankle (HKA) angles from 165° to 195° were analyzed. All patients were operated using AMA technique. According to the preoperative HKA angle, three groups of knee phenotypes (varus, straight, valgus) were defined. The bone cuts were analyzed for being anatomic (< 2mm deviation of individual joint surface) or non-anatomic (> 4mm deviation of individual joint surface). AMA reached the goals for postoperative HKA in over 93% in every group (varus: 636 cases, 94%, straight: 191 cases, 98%, valgus: 123 cases, 98%). In 0° extension, the gaps were balanced in varus knees in 654 cases (96%), in straight knees in 189 cases (97%) and in valgus knees in 117 cases (94%). A balanced flexion gap was found in a similar number of cases (varus: 657 cases, 97%, straight: 191 cases, 98%, valgus: 119 cases, 95%). In the varus group, non-anatomical cuts were performed at the medial tibia (89%) and the lateral posterior femur (59%). The straight group showed similar values and distribution for non-anatomical cuts (medial tibia: 73%; lateral posterior femur 58%). Valgus knees showed a different distribution of values, being non-anatomical at the lateral tibia (74%), distal lateral femur (67%) and posterior lateral femur (43%). In all knee phenotypes, the AMA goals were achieved in a high percentage by altering the patients' native anatomy. In varus knees, the alignment was corrected by non-anatomical cuts at the medial tibia, and in valgus knees at the lateral tibia and the lateral distal femur. All phenotypes showed non-anatomical resections on the posterior lateral condyle in approximately 50% of cases. III.

Augmented Reality Navigation Can Achieve Accurate Coronal Component Alignment During Total Knee Arthroplasty.

Background Computer-navigated knee arthroplasty has been shown to improve accuracy over conventional instruments. The next generation of computer assistance is being developed using augmented reality. The accuracy of augmented reality navigation has not been established. Methods From April 2021 to October 2021, a prospective, consecutive series of 20 patients underwent total knee arthroplasty utilising an augmented reality-assisted navigation system (ARAN). The coronal and sagittal alignment of the femoral and tibial bone cuts was measured using the ARAN and the final position of the components was measured on postoperative CT scans. The absolute difference between the measurements was recorded to determine the accuracy of the ARAN. Results Two cases were excluded due to segmentation errors, leaving 18 cases for analysis. The ARAN produced a mean absolute error of 1.4°, 2.0°, 1.1°and 1.6° for the femoral coronal, femoral sagittal, tibial coronal and tibial sagittal alignments, respectively. No outliers (absolute error of >3°) were identified in femoral coronal or tibial coronal alignment measurements. Three outliers were identified in tibial sagittal alignment, with all cases demonstrating less tibial slope (by 3.1°, 3.3° and 4°). Five outliers were identified in femoral sagittal alignment and in all cases, the component was more extended (3.1°, 3.2°, 3.2°, 3.4° and 3.9°). The mean operative time significantly decreased from the first nine augmented reality cases to the final nine cases by 11 minutes (p<0.05). There was no difference in the accuracy between the early and late ARAN cases. Conclusion Augmented reality navigation can achieve accurate alignment of total knee arthroplasty with a low rate of component malposition in the coronal plane. Acceptable and consistent accuracy can be achieved from the initial adoption of this technique, however, some sagittal outliers were identified and there is a clear learning curve with respect to operating time. The level of evidence was IV.

Unrestricted kinematic alignment corrects fixed flexion contracture in robotically aligned total knees without raising the joint line in extension

PurposeMechanically Aligned Total Knee Arthroplasty (MA TKA) typically addresses fixed flexion contractures (FFC) by raising the joint line during extension. However, in unrestricted Kinematically Aligned TKA (KA TKA) utilizing a caliper-based resection technique, the joint line is not raised. This study aims to determine the efficacy of KA TKA in restoring full extension in patients with FFC without increasing distal femoral resection, considering tibial bone resection and sagittal component positioning.MethodsA retrospective study was conducted by a single surgeon, involving patients who underwent primary robotically assisted cruciate retaining unrestricted KA TKA between June 1, 2021, and December 1, 2022. Complete intraoperative resection and alignment data were recorded, including the thickness of distal femoral and proximal tibial bone cuts. Patients with a preoperative FFC ≥ 5° (study group) were compared to those with FFC < 5° (control group). The impact of variations in tibial resection and sagittal component positioning was assessed by comparing the heights of medial and lateral resections, sagittal femoral component flexion, and tibial slope. Group comparisons were analyzed using the Wilcoxon Signed Rank Test, with a significance level set at p < 0.05.ResultsA total of 48 KA TKA procedures met the inclusion criteria, with 24 performed on women. The mean preoperative FFC in the study group was 11.2° (range: 5–25°), while the control group exhibited 1° (range: 0–4°) (p < 0.001). There were no statistically significant differences observed between the study and control groups in terms of distal femoral resections, both medially (p = 0.14) and laterally (p = 0.23), as well as tibial resection heights, both medially (p = 0.66) and laterally (p = 0.74). The alignment of the femoral component flexion and tibial slope was comparable between the two groups (p = 0.31 and p = 0.54, respectively). All patients achieved within 5 degrees of full extension at closure.ConclusionRobotic arm-assisted unrestricted KA TKA effectively restores full extension without raising the joint line during extension for patients with a preoperative fixed flexion contracture.Level of evidenceIII.

The severity of preoperative varus deformity affects the feasibility of correcting lower limb alignment with medial unicompartmental knee arthroplasty

BackgroundThe relationship between the severity of preoperative varus deformity and the amount of its correction in unicompartmental knee arthroplasty (UKA) as well as the thickness of the insert has not been well known. MethodsOne hundred and three patients who underwent medial fixed-bearing UKA with the use of the spacer block method were assessed. After the component gap in extension was measured using a UKA tensor, the pre-osteotomy gap was calculated from the thickness of the bone cuts. The relationship between the preoperative hip–knee–ankle (HKA) angle as well as the pre-osteotomy gap and the amount of change in HKA angle were analysed. Also, preoperative HKA angle and the thickness of the bone cuts were compared among groups by the insert thickness. ResultsThe mean preoperative HKA angle was 7.7 ± 3.1° varus. Patients with more varus deformity and those with a wider pre-osteotomy gap showed a more valgus change in HKA angle. As for the thickness of the insert, the preoperative HKA angle of the patients with the thinnest insert was significantly smaller (less varus) than that of those with the thicker insert while no statistically significant difference was found among the insert groups regarding the amount of the bone cuts. ConclusionsThe severity of the preoperative varus deformity as well as the intraoperative pre-osteotomy gap related to the amount of change in HKA angle. As thick inserts tended to be used in severe varus knees, the tibial bone cut can be reduced in such cases.

Difference between medial and lateral tibia plateau in the coronal plane: importance of preoperative evaluation for medial unicompartmental knee arthroplasty

BackgroundSetting bone cutting levels for different joint line orientations of the medial and lateral tibia plateaus in individual patients is not clear. We aimed to evaluate the difference between joint line orientation of the medial and lateral tibia plateaus relative to the horizontal line of mechanical axis of tibia as tibial plateau difference (TPD) for an optimal tibial bone cut in medial unicompartmental knee arthroplasty (UKA) and determine which factors could influence TPD. We aimed to investigate the effect of preoperative TPD on polyethylene liner size in medial UKA.MethodsTPD in the coronal plane were measured in 181 female patients (181 knees). To determine the morphology of proximal tibia according to the severity of osteoarthritis, the patients were classified into three groups based on diagnosis and treatment: 80 who underwent robot-assisted medial UKA, 45 who underwent total knee arthroplasty (TKA), and 56 with early-stage osteoarthritis (OA) who had conservative management. Also, we divided the medial UKA group into two groups according to TPD (greater than or less than 5 mm) and compared polyethylene liner sizes.ResultsNo significant difference was observed in TPD (p = 0.662), difference between the medial and lateral femoral condyle levels (p = 0.54), medial proximal tibial angle (p = 0.169), or posterior tibial slope (p = 0.466) among the three groups. Increased TPD was significantly associated with increased mechanical femorotibial angle(mFTA) (p < 0.01). The medial UKA group was divided into two groups according to TPD greater or less than 5 mm. Thicker polyethylene liners were used for groups with TPD greater than 5 mm (8.5 ± 0.7 mm versus 8.2 ± 0.3 mm, p = 0.01). Additionally, the proportion of patients using the thinnest polyethylene (8 mm) in each TPD group (greater or less than 5 mm) was higher in patients with TPD less than 5 mm (82.4% versus 58.7%, p = 0.038).ConclusionsPreoperative measurement of TPD is important to help surgeons predict the most appropriate bone cutting level in the coronal plane in primary medial UKA. Tibial bone resection would be likely to be thicker than needed in patients with increased TPD in medial UKA.

Tibial reference point in total knee arthroplasty in patient with proximal tibia vara: A case report.

IntroductionCenter of the intercondylar eminence at the proximal tibia had been widely used as a reference point for tibial bone cut in the Total Knee Arthroplasty (TKA) procedure. However, in the presence of preexisting tibia vara, the center of intercondylar eminence as tibial bone cut reference point often leads to varus malalignment after TKA procedure.Case report75 years old male patient complained of worsening pain on the left knee. The patient has had a history of knee osteoarthritis for the past seven years. The radiograph on the right knee revealed osteoarthritis grade 3 and left knee osteoarthritis grade 4, both with tibia vara. We planned to perform total knee arthroplasty surgery on his left knee with a preoperative planning tibial reference point of 10 mm lateral to the center. Six months after the knee replacement, there was minimal pain on activity, and full ROM was achieved on his left knee. On the radiographic X-ray evaluation, the alignment between the tibial implant surface and mechanical axis is 0.43 degrees valgus.Clinical discussionIn a varus knee malignment, the mechanical axis passes through one-third of the medial side of the knee, which makes the medial side of the implant wear off faster, resulting in the collapse of the medial tibia, thus decreasing implant survival and increasing the need for revision for TKA.ConclusionIn patients with preexisting tibia vara, tibial bone cut reference point planning before TKA procedure is important to provide longevity of implant survival and better quality of life.

Does measuring the medial gap before bone resection in total knee arthroplasty provide optimum gap adjustment and prevent bone recutting?

Objectives:The aim of this study was to demonstrate that measuring the medial gap before bone resection during total knee arthroplasty (TKA) provides an optimum gap adjustment in varus knees.Methods:Patients were separated into two groups, Group 1 being those whose medial joint gap was measured prior to bone resection and Group 2 comprising those who underwent conventional measured resection technique without measuring. The medial joint gap was measured with a custom-made gap measuring device up to the point that the knee was corrected and aligned along its mechanical axis. Medial joint gap distances, distal medial femoral bone cut thicknesses, amounts of tibial resection calculated, gap internal distances measured after cutting, and the thicknesses of the trial inserts were recorded. A comparison was made between the groups in terms of the number of patients requiring an additional tibial bone cut and the distribution of insert thicknesses.Results:Extra tibial bone resections performed in two (5.7%) patients in Group 1 and in 10 (28.6%) patients in Group 2. In Group 1, where the medial joint gap was measured, the need for an additional bone resection was statistically less. (p=0.018). In the comparison of distribution of insert size by group, the number of patients on whom an 8 mm insert had been used was significantly greater in Group 1 (p=0.024).Conclusion:Measuring the medial joint gap prior to bone resection in total knee arthroplasty may prevent repeated bone recutting and additional bone resections. Furthermore, we can use this method to avoid the disadvantages of the measured resection technique.

Choice of a Method for Blocked Intramedullary Osteosynthesis in Tibial Fractures in the Context of Topographic-Anatomical Research

Blocked intramedullary osteosynthesis has become a "gold standard" for the treatment of patients with diaphyseal fractures of the tibia. However, there is still debate about the importance and necessity of reaming the bone marrow cavity when performing intramedullary osteosynthesis.The aim is to study the individual features of the structure of the medullary cavity of the tibia in relation to intramedullary osteosynthesis, as well as to evaluate the effect of blocked intramedullary osteosynthesis with preliminary reaming and without reaming of the bone marrow cavity on the vascular supply of the tibia.Material and methods. Using morphometric and radiological methods, an experimental topographical and anatomical study was carried out on 26 dry preparations and histotopograms-plates of tibial bone cuts, as well as on 10 lower limbs of corpses with X-ray contrast injection of arterial vessels. Statistical analysis was performed using the Student's parametric test and the nonparametric MannWhitney test.Results. Particular attention was paid to the detailed study of the main parameters of the tibial bone marrow cavity that are important for the technology of blocked intramedullary osteosynthesis (size, shape and curves of the bone marrow cavity, architectonics of its narrow part, density and distribution of spongy matter in it, topography of the a. nutricia tibialis channel and distribution of its branches). To assess the invasiveness of osteosynthesis on 10 anatomical objects with preliminary injection of vessels of the lower extremity with X-ray contrast mass, blocked intramedullary osteosynthesis of the tibia with and without reaming of the bone marrow cavity was modeled.Conclusion. It was concluded that any variant of intramedullary rod insertion is accompanied by damage to a. nutricia tibialis in a narrow part of the bone marrow cavity, and reaming of the bone marrow cavity has certain advantages in view of the pronounced individual differences in the structure of the tibia.

Reproducing the Native Posterior Tibial Slope in Cruciate-Retaining Total Knee Arthroplasty: Technique and Clinical Implications.

Total knee arthroplasty (TKA) profoundly influences knee biomechanics. Using an arbitrary (often 3° to 5°) posterior tibial slope (PTS) in all cases seldom will restore native slope. This study examined whether the native PTS could be reproduced in cruciate-retaining TKA and how this would influence clinical outcome. Radiographic and clinical outcomes of 215 consecutive TKAs using the PFC sigma cruciate-retaining implant were evaluated. The tibial bone cut was planned to be made parallel to the native anatomical slope in the sagittal plane. The PTS was measured with reference to the proximal tibial medullary canal (PTS-M) and the proximal tibial anterior cortex (PTS-C) on true lateral radiographs using a picture achieving and communication system. Knee range of motion (ROM), Knee Society Score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Short Form Health Survey (SF-12) were evaluated. Mean preoperative PTS-M was 6.9°±3.3°, and mean postoperative PTS-M was 7.0°±2.4°. Mean preoperative PTS-C was 12.2°±4.2°, and mean postoperative PTS-C was 12.6°±3.4°. Preoperative and postoperative PTS were not significantly different for both techniques (P>.05). An arbitrary 3° as an acceptable range for PTS-M was achieved in 144 knees (67%) (group 1), and 71 knees (33%) had a difference of more than 3° (group 2). Group 1 had a significantly larger gain in ROM (P=.04) as well as improved Knee Society, WOMAC, and SF-12 physical scores compared with group 2 (P<.01). The modified surgical technique reproduced the native tibial slope in cruciate-retaining TKA. Reproduction of the native PTS within 3° resulted in better clinical outcomes manifested by gain in ROM and knee functional outcome scores. [Orthopedics. 2020; 43(1):e21-e26.].

A modified technique for tibial bone sparing in unicompartmental knee arthroplasty.

Previously, the authors modified the surgical technique to preserve tibial bone mass for Oxford unicompartmental knee arthroplasty (UKA). The purpose of this study was to determine the clinical outcomes and values of this modified technique. Clinical data of 34 consecutive patients who underwent the unilateral modified UKA technique (modified group, 34 knees) were retrospectively analyzed. To compare the outcome, a match-paired control group (conventional group, 34 knees) of an equal number of patients using the conventional technique system in the same period were selected and matched with respect to diagnosis, age, pre-operative range of motion (ROM), and radiological grade of knee arthrosis. Clinical outcomes including knee Hospital for Special Surgery (HSS) score, ROM, and complications were compared between the two groups. Post-operative radiographic assessments included hip-knee-ankle angle (HKA), joint line change, implant position, and alignment. The mean follow-up time was 38.2 ± 6.3 months. There was no difference in baseline between the two groups. The amount of proximal tibial bone cut in the modified group was significantly less than that of the conventional group (4.7 ± 1.1 mm vs. 6.7 ± 1.3 mm, t = 6.45, P < 0.001). Joint line was elevated by 2.1 ± 1.0 mm in the modified group compared with -0.5 ± 1.7 mm in the conventional group (t = -7.46, P < 0.001). No significant differences were observed between the two groups after UKA with respect to HSS score, VAS score, ROM, and HKA. Additionally, the accuracy of the post-operative implant position and alignment was similar in both groups. As for implant size, the tibial implant size in the modified group was larger than that in the conventional group (χ = 4.95, P = 0.035). The modified technique for tibial bone sparing was comparable with the conventional technique in terms of clinical outcomes and radiographic assessments. It can preserve tibial bone mass and achieve a larger cement surface on the tibial side.

Increased valgus laxity in flexion with greater tibial resection depth following total knee arthroplasty.

Soft tissue balancing is of central importance to outcome following total knee arthroplasty (TKA). However, there are lack of data analysing the effect of tibial bone cut thickness on valgus laxity. A cadaveric study was undertaken to assess the biomechanical consequences of tibial resection depth on through range knee joint valgus stability. We aimed to establish a maximum tibial resection depth, beyond which medial collateral ligament balancing becomes challenging, and a constrained implant should be considered. Eleven cadaveric specimens were included for analysis. The biomechanical effects of increasing tibial resection were studied, with bone cuts made at 6, 10, 14, 18 and 24mm from the lateral tibial articular surface. A computer navigation system was used to perform the tibial resection and to measure the valgus laxity resulting from a torque of 10Nm. Measurements were taken in four knee positions: 0° or extension, 30°, 60° and 90° of flexion. Intra-observer reliability was assessed. A minimum sample size of eight cadavers was necessary. Statistical analysis was performed using a nonparametric Spearman's ranking correlation matrix at the different stages: in extension, at 30°, 60° and 90° of knee flexion. Significance was set at p < 0.05. There was no macroscopic injury to the dMCL or sMCL in any of the specimens during tibial resection. There was no significant correlation found between the degree of valgus laxity and the thickness of the tibial cut with the knee in extension. There was a statistically significant correlation between valgus laxity and the thickness of the tibial cut in all other knee flexion positions: 30° (p < 0.0001), 60° (p < 0.001) and 90° (p < 0.0001). We identified greater than 5° of valgus laxity, at 90° of knee flexion, after a tibial resection of 14mm. Increased tibial resection depth is associated with significantly greater valgus laxity when tested in positions from 30° to 90° of flexion, despite stability in extension. Greater than 5° of laxity was identified with a tibial resection of 14mm. When a tibial bone cut of 14mm or greater is necessary, as may occur with severe preoperative coronal plane deformity, it is recommended to consider the use of a constrained knee prosthesis.

Different osteotomy solutions influence future total knee arthroplasty in patients with multiapical lower extremity deformities

Background: Although osteotomy achieves success on correction of lower extremity deformities, a future total knee arthroplasty (TKA) is sometimes inevitable. The zigzagged fumer and tibia after previous osteotomy can somehow influence TKA. This study aimed to figure out how different osteotomy solutions, specifically, single-level or multi-level osteotomies, influence TKA in patients with multiapical lower limb deformities. Methods: A 25-year-old female of varus deformity on both lower extremities was studied. Single-level osteotomy solutions were used to correct deformities. A templating (both two- and three-dimensional) of posterior-stabilized high-flex implant was performed for pre-TKA planning, under the circumstances of both real single-level and simulated multi-level osteotomy solutions. Parameters according to specific nomenclature were measured. Results: The average location of the center of rotation of angulation was 17 cm from the knee joint orientation line on the left side, and 12 cm on the right. On the assessment of deformity correction, the medial proximal tibial angle (MPTA) improved from 76° to 87° on the left side and from 72° to 96° on the right. The mechanical lateral distal tibial angle (mLDTA) changed from 109° to 101° on the left side and from 98° to 90° on the right. Pre-TKA templating showed that the depths of the proximal tibial bone cut were different on both sides under single or multiple level osteotomy. Thus, the selected sizes of tibial component were different accordingly. Attributed to angulation of tibial anatomical axis, an impingement of the tibial stem upon the proximal lateral tibial cortex would likely occur on the right side after single osteotomy. Conclusions: Prior correction procedures influence future TKA in patients with severe multiapical deformities in lower extremities. A sufficient and excellent preoperative plan of osteotomy is necessary not only for achieving present correction of alignment, but also for achieving a successful TKA yet to come.