Tibial Anatomical Axis Research Articles

THE TEN-YEAR RADIOLOGICAL RESULTS OF THE UNCEMENTED OXFORD MEDIAL COMPARTMENT KNEE ARTHROPLASTY

IntroductionThe Oxford Unicompartmental Knee Replacement (OUKA) is the most popular unicompartmental knee replacement (UKR) in the New Zealand Joint Registry with the majority utilising cementless fixation. We report the 10-year radiological outcomes.MethodsThis is a prospective observational study. All patients undergoing a cementless OUKA between May 2005 and April 2011 were enrolled. There were no exclusions due to age, gender, body mass index or reduced bone density.All knees underwent fluoroscopic screening achieving true anteroposterior (AP) and lateral images for radiographic assessment. AP assessment for the presence of radiolucent lines and coronal alignment of the tibial and femoral components used Inteliviewer radiographic software. The lateral view was assessed for lucencies as well as sagittal alignment.Results687 OUKAs were performed in 641 patients. Mean age at surgery was 66 years (39–90yrs), 382 in males and 194 right sided. 413 radiographs were available for analysis; 92 patients had died, 30 UKRs had been revised and 19 radiographs were too rotated to be analysed the remainder were lost to follow-up. Mean radiograph to surgery interval was 10.2 years (7.1–16.2yrs).RLLs were identified in zone 1 (3 knees), zone 2 (2 knees), zone 3 (3 knees), zone 5 (3 knees), zone 6 (2 knees) and zone 7 (42 knees). No RLL had progressed, and no case had any osteolysis or prosthesis subsidence.Alignment in the coronal plane: mean 2.90° varus (9.30° varus - 4.49° valgus) of the tibial component to the tibial anatomic axis and the femoral component in mean 4.57° varus (17.02° varus - 9.3° valgus). Sagittal plane posterior tibial slope was a mean 6.30° (0.44° -13.60° degrees) and mean femoral component flexion of 8.11° (23.70° flexion – 16.43° extension).ConclusionThe cementless OUKA demonstrates stable fixation with low revision rates at our centre supporting results earlier published by the design centre.

Evaluation of increased posterior tibial slope as a risk factor for anterior cruciate ligament injury

Individuals who sustain anterior cruciate ligament (ACL) injury have an increased risk of developing early onset post traumatic osteoarthritis of the knee despite treatment received [1]. An increase in the posterior tibial slope is postulated to increase the risk of ACL rupture [2]. Measurement of the posterior tibial slope in individuals would serve as a means of screening and identifying those at increased risk of developing ACL injuries to take measures towards prevention. The aim was to measure and compare the mean value of the posterior tibial slope in adult patients with or without ACL injury. This was a hospital-based case-control study comprising 80 patients divided into two matched groups. Posterior tibial slope was measured on the plain lateral radiograph of the knee using the proximal tibial anatomic axis measurement protocol in all participants. Independent sample t-test was used to compare the means of the measured posterior tibial lope between cases and controls. The difference in the measured mean posterior tibial slope between the ACL injured group and the non-ACL injured group was found to be statistically significant with those in the ACL injured group having higher mean values (12.71 ± 1.2° vs 10.25 ± 1.1°) with a P value of < 0.001. Individuals with ACL injury have a significantly greater posterior tibial slope than those without ACL injury when measured on the lateral plain radiograph of the knee using the proximal tibial anatomic axis measurement protocol.

Evaluation of the relationship of posterior tibial slope with gender and age in Turkish population with 3 different methods

BackgroundThis study aimed to reveal the posterior tibial slope (PTS) angle with 3 different methods in a large case group in the Turkish population. In addition, the reproducibility of the measurement methods used was questioned while determining the age groups, gender and side relationship of this angle.Materials and methodsIn our retrospective study, radiographs of both knees were evaluated in all 610 patients (344 women, 56.4%) aged 25–65 years. PTS angles were measured by a radiologist and an orthopedist using anterior tibial cortex (ATC), posterior tibial cortex (PTC) and proximal tibial anatomical axis (PTAA) methods. The relationship of these angles with age group and gender, and the intra-class and inter-class correlations of all three methods were evaluated.ResultsThe mean and standard deviation (SD) of PTS angle was 11.03 ± 2.33° with ATC method, 6.25 ± 2.22° with PTC and 8.68 ± 2.16° with PTAA, and the difference was significant (p < .001). In the evaluation according to age groups, the highest mean PTS angles were detected in cases aged 25–35 (9.63 ± 1.97° [mean ± SD] by PTAA method), and there was a significant difference in comparison with other age groups (p < .05). In comparison with age groups, higher mean PTS angles were found in women and on the right side, but the difference was not statistically significant (p > .05). The intraclass and interclass correlation coefficient (ICC) of all three methods was excellent (ICC > 0.91).ConclusionThis study emphasizes that the mean PTS angle in Turkish population is higher than the angle values ​​recommended by prosthesis manufacturers, and factors such as patient age and gender should be calculated in order to ensure more effective prostheses to be applied to patients.

Straightness of Central Anatomical Axes of Human Tibia–Fibula System: Role of Fibula and Its Importance in Biomechanics

Abstract Fracture may occur in human lower leg bones considering varying loads acting on them while performing various functions. Implants, commonly used in healing the fractures, must be properly aligned with the bones' anatomical axes for their proper functioning. While attempts to establish tibial anatomical axis have been made previously, combined central anatomical axis of human tibia and fibula remains unexplored. In this study, profiles of individual and combined central anatomical axes of tibia and fibula have been obtained using computed tomography (CT). These profiles are found to be approximately straight with the deviation from straight line for the centroidal axis of the combined system being approximately half of that for the tibia. It is further utilized in assessing the role of fibula in determining the critical stresses in the tibia with the help of static finite element analysis (FEA) of a tibia–fibula model. Even though fibula takes a smaller proportion of the total axial load, its absence increases the compressive stresses in the tibia due to increased bending moments at the critical cross section. Furthermore, FEA has been carried out to understand the clinical significance of the mismatch in the centroidal axis of an implant and its parent bone taking the example of the human tibia alone. FEA suggests that these central anatomical axes are in fact the load bearing axes of the bones and any misalignment of implant with the central anatomical axis may lead to patient discomfort and premature failure of the implant.

Poster 268: The Relation Between Posterior Tibial Slope Angle and Bilateral ACL Tear

Objectives: Increased posterior tibial slope (PTS) is a risk factor for primary anterior cruciate ligament (ACL) tear, as well as subsequent ACL graft tear. Prior literature has shown conflicting relationships between an increased PTS and bilateral ACL tears. The purpose of this study is to compare PTS angles for patients who had bilateral ACL tears to those who had only sustained a unilateral ACL tear. Methods: Retrospectively we identified patients who had bilateral and unilateral ACL tears at our institution over the last 10 years. Those who had bilateral surgery were matched to those who had unilateral surgery on a ratio of 1:1 based on age, sex, and BMI. Patients with unilateral ACL reconstruction were excluded if they had subsequent revisions or were less than 5 years post-operative. Lateral knee radiographs were used to measure the posterior tibial slope. The tibial axis was found using the circles measurement method which consisted of drawing circles along the tibial shaft and placing a line through the center of each to estimate the anatomical tibial axis. The PTS was then defined as the angle between the perpendicular line to this axis and the tibial plateau tangent line. Three blinded orthopedic residents performed these measurements. In addition to comparison of mean PTS between cohorts, both cohorts were stratified into “high slope” and “low slope” using 10-degress of PTS as a cutoff. An interclass correlation coefficient (ICC) was then calculated. Results: Fifty-three patients with bilateral ACL tears were successfully matched to 53 patients with unilateral tears. The average PTS in patients with bilateral ACL tears was found to be significantly higher than patients with unilateral ACL tears (11.17 vs. 9.72, p = 0.005). An intraclass correlation coefficient was calculated to 0.80 (95% confidence interval: 0.75 – 0.85). These cohorts were then stratified by the aforementioned sub-groups, finding that 69.8% of the bilateral cohort had more than 10-degrees of PTS, while this was true for only 46.4% of the unilateral cohort (p = 0.006). Conclusions: These results demonstrate that patients with bilateral ACL tears have higher PTS angles than those who only had unilateral ACL tear. Clinicians should consider routinely assessing PTS in a newly-presenting patient with an initial ACL tear, as marked deviations from the general population could be a predisposing risk factor for subsequent contralateral tear. Further prospective research is necessary to determine if patients with unilateral ACL tears who present with this radiographic finding are at greater risk for contralateral tear.

Normal coronal kinematics of dynamic alignment and bony positions relative to the ground in three-dimensional motion analysis during gait: A preliminary study.

During gait, healthy knee coronal kinematics of each bony axis and lower extremity alignment are important because they could be useful as reference data for several surgeries and provide clarification of the etiology of diseases around the knee in healthy participants; however, it remains unknown. The objective of this study was to clarify the kinematics of lower extremity alignment and the bony axes relative to the ground during gait, focused on the coronal plane, in healthy individuals by applying our unique three-dimensional (3D) motion analysis. The study included 21 healthy individuals, including 9 healthy females and 12 healthy males with an average age of 36 ± 17 years. Knee kinematics were calculated in a gait analysis by combining the data from a motion-capture system and a 3D lower-extremity alignment assessment system on biplanar long-leg radiographs by using a 3D-2D registration technique. The main kinematic parameters were the dynamic position change relative to the ground, applying the femoral anatomical axis (FAA), tibial anatomical axis (TAA), and dynamic alignment in the coronal plane during the stance phase of gait. The average changes in FAA, TAA, and dynamic varus alignment were 3.7° ± 1.2°, 3.5° ± 0.8°, and 3.0° ± 1.2°, respectively. The TAA tilted laterally during the loading response and a plateau area appeared afterwards; the FAA gradually inclined laterally until the terminal stance phase, and the dynamic alignment showed varus angular change during the loading response. The tibia and femur were found to change approximately 2-5° of the position of the bony axes relative to the ground. In terms of clinical relevance, our findings can be used to clarify the etiology of diseases around the knee joint and as reference data for surgeries.

High prevalence of increased posterior tibial slope in ACL revision surgery demands a patient-specific approach.

To determine the prevalence of an "increased posterior tibial slope (PTS)" (PTS ≥ 12°) in a population with one, two or ≥ three anterior cruciate ligament (ACL) graft insufficiencies. Furthermore, to investigate whether the prevalence of an increased PTS and the absolute PTS increases with an increasing number of ACL graft insufficiencies, as well as to determine the survival time of the first ACL graft. Patients diagnosed with an ACL graft insufficiency between January 2021 and March 2022 were included. The PTS was measured using the proximal anatomical tibial axis on long lateral knee radiographs. Patients were divided into 3 groups depending on the number of ACL graft insufficiencies: group A (1 graft insufficiency), group B (2 graft insufficiencies) and group C (≥ 3 graft insufficiencies). The prevalence of increased PTS and absolute PTS between groups was compared alongside the survival of the first ACL graft between patients with or without increased PTS. Two-hundred and six patients (147 males/59 females) met the inclusion criteria. 73 patients showed an increased PTS [prevalence 35% [95% confidence interval (CI) (29%; 42%)]. 155 patients were found in category A, 42 patients in B and 9 patients in C. The prevalence of increased PTS for group A, B and C was, 32% [95% CI (25%; 40%)], 38% [95% CI (23%; 53%)] and 78% [95% CI (51%; 100%)], respectively. The prevalence of increased PTS and mean PTS did not increase significantly between group A and B. However, both parameters increased significantly between group A and C, and group B and C (p < 0.05). The survival time of the first ACL graft in patients with or without an increased PTS was 3 (interquartile range (IQR) 5) and 6years (IQR 9), respectively (p < 0.05). There is a 35% prevalence of increased PTS in the studied ACL graft insufficient patient cohort. The survival of the first ACL graft is shorter in patients with an increased PTS. Surgeons should be aware of the high prevalence of increased PTS when consulting patients for revision ACL reconstruction as it is an important risk factor for recurrent instability.

Progress on measurement of tibial posterior slope and its biomechanical relationship with posterior cruciate ligament

The most reliable and convenient measurement method of tibial posterior slope(TPS) and its biomechanical relationship with posterior cruciate ligament (PCL) are still controversial. For X-ray measurement, it is recommended to use full-length lateral X-ray of the lower extremity in quatrous section, which has advantage of highly repeatable and common in the daily diagnosis and treatment process, but it is only applicable to patients with tibial rotation within 15°. When the rotation exceeds 30°, it is difficult to identify the inner contour of platform and is no applicable. If it is only used for daily diagnosis and treatment evaluation, when tibial rotation angle is less than 15°, lateral knee X-ray also has a certain reference significance, but the accuracy could not meet requirements of higher clinical research. For CT measurement method, it could correct tibial rotation, but using the fitting point to measure tibial posterior slope on three-dimensional CT reconstruction is only applicable to knee joint without degeneration, more osteophyte affects the way of using fitting point to determine the plane of tibia with real tibia platform conformity degree, have some limitations. For measurement of MRI, it could not only correct tibial rotation, but also minimize the effect of osteophytes by using tibial anatomical axis as the reference axis, which is a good measurement method. For the biomechanical relationship between tibial posterior slope and tibial posterior slope, increased tibial posterior slope indirectly alleviates tension of PCL through tibial anterior displacement or directly reduces load on posterior cruciate ligament in tibial osteotomies, suggesting a protective mechanism for tibial posterior slope;in total knee arthroplasty with cruciate ligament preserved, the size of tibial posterior slope will affect roll back mechanism of femur. When affected knee with PCL injury, it should be avoid to release then aggravate injury, and the stress could be alleviated by increasing tibial posterior slope appropriately. There has been no unified conclusion on the range of tibial posterior slope that is most beneficial to PCL. The natural tibial posterior slope is between 7 ° and 10°, which is considered to be the most beneficial to protection of PCL, but further studies are needed according to the differences in patients' bone status, surgical methods and so on.

A novel way of quantifying bone defect in primary total knee replacements using plain radiographs.

Bone defect assessment in primary advanced knee arthritis can present a challenge for the surgeon and lead to unfavourable outcomes if not adequately determined during preoperative planning. The aim of this study was to introduce a new, simple and quick way to assess and quantify bone defect using short film radiographs and utilising it to choose the total knee prosthesis. This is a prospective case series of patients who underwent TKA (Total Knee Arthroplasty) using various types of prostheses. Three different angles - Tibiofemoral angle, MPTA (medial proximal tibial angle), and JLCA (joint line convergence angle) - were measured preoperatively to evaluate limb alignment, placement of the tibial, and femoral components of total knee prosthesis. Postoperatively roentgenographic index introduced by Lotke et al was used to assess our preoperative methodology. The American knee society score was used pre- and postoperatively up to one year. A total of eight knees of six patients were analysed (four males, two females). The mean age of the patients was 57.75±5.701 years. All the knees were in varying degrees of varus deformity preoperatively. The accuracy of the preoperatively used radiological angles was analysed by postoperative measurement of tibiofemoral angle (d), tibial anatomical axis (b) and femoral anatomical axis (a), and Roentgenographic index as suggested by Lotke et al. Postoperatively, all the knees were in valgus with tibiofemoral angle (d) 6.50±0.926, tibial component alignment (b) mean was 89±1.195, and femoral component alignment (a) mean was 5.13±0.991 valgus. Mean roentgenographic index was 89.38±3.292. American knee society score improved at one-year follow-up postoperatively and was statistically significant with p<0.001. In this study, a new classification for bone defects in primary arthritic knees by utilising simple plain radiograph short films and as a guide for implant selection is proposed.

Comparison of Robotic and Conventional Unicompartmental Knee Arthroplasty Outcomes in Patients with Osteoarthritis: A Retrospective Cohort Study.

Robotic-arm-assisted unicompartmental knee arthroplasty (RUKA) was developed to increase the accuracy of bone alignment and implant positioning. This retrospective study explored whether RUKA has more favorable overall outcomes than conventional unicompartmental knee arthroplasty (CUKA). A total of 158 patients with medial compartment osteoarthritis were recruited, of which 85 had undergone RUKA with the Mako system and 73 had undergone CUKA. The accuracy of component positioning and bone anatomical alignment was compared using preoperative and postoperative radiograph. Clinical outcomes were evaluated using questionnaires, which the patients completed preoperatively and then postoperatively at six months, one year, and two years. In total, 52 patients from the RUKA group and 61 from the CUKA group were eligible for analysis. The preoperative health scores and Kellgren–Lawrence scores were higher in the RUKA group. RUKA exhibited higher implant positioning accuracy, thus providing a superior femoral implant angle, properly aligned implant placement, and a low rate of overhang. RUKA also achieved higher accuracy in bone anatomical alignment (tibial axis angle and anatomical axis angle) than CUKA, but surgical time was longer, and blood loss was greater. No significant differences were observed in the clinical outcomes of the two procedures.

Is Proximal Tibia Sufficient for Accurate Measurement of Tibial Slope Angles on Three-dimensional Tomography-based Anatomical Models?

Tibial slope measurements performed using only the proximal part of tibia ignore the native tibial anatomical axis. Our first aim is to measure the native medial, lateral and total tibial slope angles of gender groups using the whole tibial anatomical axis on computerized tomography-based three-dimensional anatomical models. The second aim is to determine the correlation between proximal and whole tibial anatomical axis for measurement of medial, lateral, and total tibial slope angles. We randomly selected 100 females and 100 males between 18-60 years of age. Three-dimensional anatomical models of right and left tibia were created. The gender-specific differences of medial, lateral, and total tibial slope angles according to proximal and whole tibial anatomical axis were measured. Correlation coefficients (r) of medial, lateral, and total tibial slope angles measured with proximal and whole tibial anatomical axis were calculated. The mean age was 47.1 years. A statistically significant difference was observed between female (7.1 ± 3) and male (8.2 ± 2.5) groups in terms of mean lateral tibial slope angles according to the whole tibial anatomical axis (p=0.008). A strong correlation between proximal and whole tibial anatomical axis for all tibial slope angle measurements was detected. The method we determined for 3D measurement of medial, lateral and total tibial slope angles using proximal tibial anatomical axis has a strong correlation with slope angles measured in accordance with the whole tibial anatomical axis. Our 3D tibial slope angle measurement method on the proximal tibia has high reliability and could be used in the daily practice.

Medial and Lateral Posterior Tibial Slope Are Independent Risk Factors for Noncontact ACL Injury in Both Men and Women.

Background:Higher posterior tibial slope (PTS) is a risk factor for anterior cruciate ligament (ACL) injury in men and women. The individual contribution of the lateral (LPTS) and medial (MPTS) slope has not yet been investigated.Purpose:To determine whether either the LPTS or the MPTS is an independent risk factor for ACL injury, and to determine sex-specific differences between patients with ACL-deficient and ACL-intact knees.Study Design:Cohort study; Level of evidence, 3.Methods:We reviewed knee magnetic resonance (MR) images performed on ACL-deficient and ACL-intact knees between January 2018 and June 2020 at a single institution. Inclusion criteria were isolated ACL injury and noncontact mechanism (ACL-deficient group) and nonspecific knee pain and no history of injury (ACL-intact group). Exclusion criteria for both groups were the following: previous knee surgery; meniscal, collateral ligament, posterior cruciate ligament, or multiligamentous injuries; radiological evidence of osteoarthritis; and chondral damage on the tibia. The MR images were used to establish the posterior bony slope at 25%, 50%, and 75% from the medial and/or lateral border of the tibial plateau with respect to the proximal tibial anatomic axis. One-way analysis of variance (ANOVA) was used to determine differences in PTS at the 25%, 50%, and 75% distances for the medial and lateral tibial plateau between the groups and between the sexes.Results:Overall, 325 images were included (mean age, 36.1 ± 11.1 years; 142 ACL-deficient images [82 men and 60 women]; 183 ACL-intact images [112 men and 71 women]). MPTS and LPTS were significantly higher at 25%, 50%, and 75% in the ACL-deficient group (range, –2.7° to –5.7°) compared with the ACL-intact group (range, –2.1° to 1.5°; P = .00001). Similarly, MPTS and LPTS were significantly different in men versus women (P = .00001). ANOVA revealed that there were no significant differences in PTS between men and women for all measures (MPTS, LPTS, ACL-deficient, ACL-intact; P = .68).Conclusion:The study results demonstrated that higher MPTS and LPTS is a potential risk factor for ACL injury in both men and women. However, despite being highly statistically significant, the differences between groups and sexes were small and may not be clinically relevant.

Establishing a New Patient-Specific Implantation Technique for Total Ankle Replacement: An In Vitro Study.

Revision rates after total ankle replacements (TARs) are higher compared with other total joint replacements. The present study aimed to establish a new patient-specific implantation (PSI) technique for TAR. A total of 10 complete Caucasian cadaver legs had whole leg computed tomography scans. The individual geometrical ankle joint axis was determined, and based on this axis, the position of the prosthesis was planned. We assessed prosthesis placement, guiding block position, and preoperative and postoperative ankle rotational axes. The guiding block position interobserver reliability was 0.37 mm 0.45 (mean ± SD) for the tibial guiding block. The value for the first talar guiding block was 1.72 ± 1.3 mm and for the second talar guiding block, 0.61 ± 0.39 mm. The tibial slope as well as the frontal angles of the anatomical tibial axis compared to the tibial and talar articular surfaces showed no statistically relevant differences with numbers available. The deviation of the assessed preoperative joint axis to the postoperative joint axis was 14.6° ± 7.8. The present study describes the results of an establishing process of a new PSI technique for TAR. The reliability of guiding block positioning and, thereby, prosthesis placement is sufficient. Biomechanical study.

The effect of anatomical tibia vara on the coronal alignment of tibial component in total knee arthroplasty: A radiographic analysis

Survivorship in total knee arthroplasty depends on the restoration of the coronal alignment of its components. Failure to restore this may decrease the longevity of TKR. The prevalence of tibia vara in patients with osteoarthritis of the knee undergoing TKA is quite high. We wanted to assess the effect of the varus angulation in the proximal metaphysis of the tibia on tibial component malposition in the coronal plane in patients undergoing total knee replacement. Patients who underwent TKA for primary osteoarthritis of the knee and with more than two years of follow-up were included. The extra-articular tibial deformity was assessed by measuring the angle between the anatomical and mechanical axis of the tibia. The coronal alignment of the femoral and tibial components was measured using lateral distal femoral angle and medial proximal tibial angle.Preoperatively,73 (90.12%) patients were having a neutral tibial anatomical axis and 8(9.9%) patients were having varus angulation in the proximal tibia.Postoperatively,18(22.2%) patients had a neutral mechanical axis. There were 14(17.2%) patients with more than 3 degrees of varus mechanical axis and 41(50.6%) patients had less than 3 degrees of varus mechanical axis alignment. 2 (2.5%) patients had more than 3-degree valgus mechanical axis and 6 (7.4%) had less than 3 degrees valgus mechanical axis. Postoperatively, out of 8 patients with pre-operative tibia vara, only 2(25%) patients had neutral placement of the tibial component. 6 (75%) had both tibial and femoral component malalignment. Out of the 73 patients with pre-operatively neutral tibial axis, 40(54.7%) patients had both tibial and femoral component malalignment. 8 (11%) patients had only tibial and 9(12.3%) patients had only femoral component malalignment. In 16 (19.1%) patients, there was no malalignment of both. There was no significant relationship between the tibial anatomical axis malalignment and the tibial component alignment in patients undergoing TKA for primary osteoarthritis.

Posterior tibial slope measurements based on the full-length tibial anatomic axis are significantly increased compared to those based on the half-length tibial anatomic axis.

This study aimed to compare the difference in posterior tibial slope (PTS) measurements based on the full-length and half-length tibial anatomic axes of the same group of patients. It was hypothesized that the obtained PTS values would be affected by the length of tibia chosen during the measurements. Full-length true lateral tibia radiographs were obtained for each patient who underwent anterior cruciate ligament reconstruction (ACLR) in our department. PTS measurements were obtained by measuring the angle between the full-length or half-length tibial anatomic axis and an average of the lateral and medial tibial plateau. The anatomic axis was defined as the center of the tibial diaphysis. The PTS measurements from the full-length and half-length true lateral tibia radiographs were obtained and compared. Additionally, the absolute difference and the relationship between the two PTS measurements were calculated and analyzed. A total of 200 ACL-injured patients were included in this study. The average PTS values using the anatomic axis were 15.9 ± 3.7° and 14.1 ± 3.7° on full-length and half-length true lateral tibial radiographs. There was a significant difference between the measurements with the full-length and half-length tibial radiographs (P < 0.01). Additionally, 49.5% (n = 99) of patients had ≥ 2.0° differences between the full-length and half-length anatomic axis PTS measurement techniques; meanwhile, a strong and significant linear relationship (r = 0.95; P < 0.001) was identified between the two PTS measurements. There were significant differences and linear relationships between PTS measurements that measured the anatomic axis from full-length and half-length true lateral tibia radiographs. Therefore, the obtained PTS values were strongly associated with the length of tibia chosen during the measurements. Surgeons should pay more attention to the measurement techniques and the tibial length when considering the role of PTS in ACL injury and ACLR failure. Knowledge of the association is very important for calculating potential closing wedge proximal tibial osteotomies to correct excessive PTS in the setting of ACLR failures. IV.

Relationship between the bony correction angle and mechanical axis change and their differences between closed and open wedge high tibial osteotomy

BackgroundThe purpose of this study was to investigate the relationship between the bony correction angle and mechanical axis change and their differences between closed wedge high tibial osteotomy (CWHTO) and open wedge high tibial osteotomy (OWHTO).MethodsA total of 100 knees of 89 patients who underwent OWHTO (50 knees) or CWHTO (50 knees) between 2011 and 2015 with a clinical follow-up for 1 year and a radiological follow-up for 1 month were investigated in a case control study. Anteroposterior radiographs of the knee and full-length leg were taken in the standing position using digital acquisition. The femorotibial angle (FTA), % mechanical axis deviation (MAD), % anatomical tibial axis deviation (ATAD), % mechanical tibial axis deviation (MTAD), mechanical medial proximal tibial angle (mMPTA), and joint line convergence angle (JLCA) were measured on preoperative and postoperative radiographs using a dedicated software.ResultsCWHTO resulted in a greater variation between the tibial anatomical and mechanical axes than OWHTO (P < 0.05), and a greater soft tissue correction than OWHTO (P < 0.05). However, no significant difference was found between CWHTO and OWHTO in the ratio of MAD change to the correction angle. When the osteotomy was planned with the same bony correction angle, %MAD passed more laterally in OWHTO than in CWHTO (P < 0.05). These results suggested a lesser valgus bony correction ratio due to greater medial shift of the tibial axis and greater valgus compensation of the soft tissue in CWHTO compared to OWHTO.ConclusionsThe ratio of mechanical axis shift to the correction angle differed in preoperative planning, but postoperative alignment was comparable between opening wedge and closed wedge high tibial osteotomy.

Accuracy and Reproducibility of a Patient-Specific Instrumentation in Total Ankle Arthroplasty

Category:Ankle ArthritisIntroduction/Purpose:Ankle arthritis (OA) is a frequent and debilitating disease with the two primary surgical options being ankle arthrodesis or total ankle arthroplasty (TAA). TAA has the advantages maintenance of range of motion (ROM), a more normalized gait and potentially improved functional outcome over arthrodesis. Malaligned protheses have been demonstrated to have increased peak component pressures, potentially leading to component loosening, failure and overall worse outcomes. One TAA system uses pre-op CT to build patient-specific surgical instrumentation, with purported benefit of more reliable and accurate component positioning. The goal of this study is to evaluate reproducibility and accuracy of this system by surgeons without affiliation with the prosthesis design team.Methods:A retrospective radiological study was performed including two centers with four fellowship-trained foot and ankle surgeons using the patient-specific TAA system. All patients operated on between 2015-2018 were included. The primary outcome was alignment of the tibial implant in coronal and sagittal orientation relative to the tibia anatomic axis. All measurements were performed in duplicate an orthopaedic foot and ankle fellow and a musculoskeletal fellowship-trained radiologist. Secondary outcomes included accuracy of prediction of tibial and talar component size implanted compared to the engineered pre-operative plan, rate of prosthesis revision (at least one component) and overall re-operation rate.Results:79 patients were included in the final review. The mean absolute deviation of the tibial component from tibial anatomical axis was 1.31° +/- 1.14in the coronal plane and 2.68°+/- 1.74 in sagittal alignment. 94.7 % of the implants were implanted within 3°of varus or valgus and 73.7% within 3°of dorsiflexion or plantiflexion. 86 % of the implanted tibial component were of the size predicted by the pre-op plan whereas it was found to be the case in 63 % of the talar component.At a mean follow-up of 22 months(3-52), two TAA (2.5%) have been revised due to aseptic tibial implant loosening.Conclusion:The patient-specific guide has been found to be a reliable system for coronal tibial implant alignment but less in the sagittal plane in the hand of surgeons not involved in the design of any TAA system. Accuracy of prediction of the tibial component size is high, moderate on the talar side. In this series there was a low rate of early component revision (2.5 %).

Evaluation of tibial rotational axis in total knee arthroplasty using magnetic resonance imaging

Surgeon-dependent factors such as optimal implant alignment of the tibial component are thought to play a significant role in the outcome following primary total knee arthroplasty (TKA). In addition, tibial component malrotation is associated with pain, stiffness, and altered patellofemoral kinematics in TKA. However, measuring tibial component rotation after TKA is difficult. Therefore, the purpose of this study was to find a reliable method for positioning the tibial component in TKA. To investigate the morphology of the tibial plateau, 977 patients' knees (829 females and 148 males) were evaluated using MRI. The relationships between the femoral transepicondylar axis (TEA), Akagi line, posterior tibial margin (PTM), medial third of the tibial tubercle (MTT), and anatomical tibial axis (ATS) were investigated in this study. In addition, gender difference in tibial rotational alignment were evaluated. Relative to the TEA, the MTT and ATS were externally rotated by 0.5° ± 4.4° and 0.5° ± 5.4°, respectively, while Akagi line and PTM were internally rotated by 3.7° ± 4.5° and 9.9° ± 6.1°, respectively. Gender differences were found in MTT, Akagi line and ATS (P < 0.05). Our result showed that the rotational alignment led to notable variance between femoral and tibial components using fixed bone landmarks. The MTT and ATS axes showed the closest perpendicular aspect with projected TEA. And the MTT and Akagi axes showed the reduced variance. In addition, PTM is not a reliable landmark for rotation of the tibial component. Based on the results of this study, surgeons may choose the proper anteroposterior axis of the tibial component in order to reduce rotational mismatch and improve clinical outcomes.

Posteromedial Open-Wedge High Tibial Osteotomy to Avoid Posterior Tibial Slope Increase

The primary aim was to evaluate the influence of the surgical modification on posterior tibial slope (PTS) and patellar height in open-wedge high tibial osteotomy (OWHTO). The secondary aim was to evaluate the influence of preoperative mechanical axis deviations (MA) on PTS METHODS: Between January 2014 and February 2016, patients with a diagnosis of medial-compartment osteoarthritis who had undergone OWHTO with posteromedial osteotomy technique with a minimum follow-up of 3 months were included in this retrospective study. Preoperative and postoperative PTS angles with 3 different methods and patellar heights with respect to the Insall-Salvati and Caton-Deschamps indices were measured on lateral radiographs by 2 observers. Patients were grouped according to preoperative MA (either <10° or ≥10°). PTS changes were compared between groups RESULTS: Thirty consecutive knees of 28 patients were evaluated. Preoperative mean PTS angles were 9.50° ± 4.47° (posterior tibial cortex referenced), 11.51° ± 4.50° (tibial anatomical axis referenced), and 10.80° ± 4.58° (posterior fibular cortex referenced); postoperative angles were 6.10° ± 4.23°, 8.78° ± 4.57°, and 8.11° ± 4.55°, respectively. PTS was significantly decreased postoperatively with respect to all 3 methods (P < .0001). Mean preoperative and postoperative Insall-Salvati indices were 1.04 ± 0.16 and 1.07 ± 0.17, respectively (P= .088). Mean preoperative and postoperative Caton-Deschamps indices were 0.87±0.18 and 0.78 ± 0.18, respectively (P= .017). PTS changes were not statistically significant between groups with respect to MA (P values .861, .723, and .727, respectively) CONCLUSIONS: It is possible to preserve and even decrease PTS with an OWHTO performed posterior to MCL in a posteromedial to anterolateral direction. Level IV, retrospective case series.

Effects of sagittal tibial osteotomy on frontal alignment of the knee and patellar height.

The aim of this study was to evaluate the radiographic effect of sagittal tibial osteotomy (STO), flexion tibial osteotomy (FTO) and deflexion tibial osteotomy (DTO) around the knee. It has been hypothesized that proximal STO modifies patellar height and could cause varus/valgus changes of the anatomical tibial axis: The purpose of the study was to verify this and to analyse these modifications. Patients underwent proximal STO in our department between 2007 and 2018: overall 28 consecutive patients (19 males, 9 females; 28 knees). Twelve patients underwent DTO, and 16 patients underwent FTO. Two independent observers measured the pre-operative and post-operative radiological indexes: posterior tibial slope, Caton-Deschamps Index (CDI) and Modified Insall-Salvati Index (MISI) in the lateral views; medial Tibial Plateau-Tibial Shaft (mTPTS) and medial Femoral Shaft-Tibial Shaft (mFTA) anatomical angles were measured in the frontal plane. No complications were reported at the average follow-up of 1.6 ± 1.1years. The mean mTPTS significantly increased from 0.6° ± 2.4° pre-operatively to 2.9° ± 2.6° of varus post-operatively (DTO (pre-operative 0.3 ± 3.1°, post-operative 2.4 ± 2.1°, ns); FTO (pre-operative 0.9 ± 1.9°, post-operative 3.2 ± 3.0°, P < 0.05)). The mean mFTA significantly reduced from 186.2° ± 4.9° pre-operatively to 182.7° ± 3.9° post-operatively (DTO (pre-operative 183.4 ± 3.3°, post-operative 180.6 ± 3.5°, ns); FTO (pre-operative 188.5 ± 4.9°, post-operative 184.4 ± 3.4°, P < 0.05)). The overall analysis reported no differences statistically significant in patellar height indexes. The main finding of this study is that STO slightly modifies tibial anatomical axes. This finding is more evident in FTOs. This surgical technique, due to its design, does not influence the patellar height. The tibial tuberosity osteotomy, performed in most of the cases to better expose tibial metaphysis and to avoid patellar tendon damages, provides another benefit that is the possibility to easily preserve the native patellar height. Sagittal tibial osteotomies slightly modify tibial anatomical axes in frontal plan without influencing the patellar height. This surgical procedure resulted to be effective and reliable in correcting the sagittal knee alignment but reporting, particularly of FTO, varus changes of anatomical tibial axis.