[Difficulties and reproducibility of radiological measurement of the proximal tibial axis according to Lévigne]

Do age, gender, and region affect tibial slope? A multi-center study

INTRODUCTION

Tibial slope is a parameter that is important to recognize in knee kinematics and knee surgery. A very wide range of values governing posterior tibial slope exist in the literature. This study is based on the hypothesis that age, gender and region may have an effect on the tibial slope.

MATERIALS AND METHODS

A total of 1800 lateral knee radiographies from five different countries [Turkey, Germany, Italy, Spain, and the United Kingdom (UK)] were utilized to measure the native posterior tibial slope. Participants were categorized in deciles with each decade of age after 40 years determined as a separate age group. Accordingly, four different age categories were formed in total, namely, the 40- to 49-, 50- to 59-, 60-69, and 70- to 79-year-old groups. Patients with severe knee osteoarthritis, those with a history of arthroscopic and open surgery around the knee, and those with severe morbid obesity and those outside the specified age group were excluded from the study. The angle between the line tangential to the medial tibial plateau and the proximal anatomical axis of the tibia was measured.

RESULTS

The tibial slope values of both males and females in the Turkish population were found to be higher than those in other populations. It was observed that tibial slope values increased with age in females in all populations, except for those in the Spanish and UK populations. In the male population, it was found that tibial slope values increased with age in all populations except in the Spanish population.

CONCLUSIONS

Region, age, and gender affect tibial slope in different populations in various ways. Our study shows that the region an individual lives in and living conditions affect the tibial slope.

Custom total knee arthroplasty facilitates restoration of constitutional coronal alignment

PURPOSE

To describe a strategy for coronal alignment using a computed tomography (CT) based custom total knee arthroplasty (TKA) system, and to evaluate the agreement between the planned and postoperative Hip-Knee-Ankle (HKA) angle, Femoral Mechanical Angle (FMA) and Tibial Mechanical Angle (TMA).

METHODS

From a consecutive series of 918 primary TKAs, 266 (29%) knees received CT-based posterior-stabilized cemented custom TKA. In addition to a preoperative CT-scan, pre- and post-operative radiographs of weight-bearing long leg, anterior-posterior and lateral views of the knee were obtained, on which the FMA, TMA and HKA angles were measured. CT-based three-dimensional (3D) models enabled to correct for cases with bony wear by referring to the non-worn areas and to estimate the native pre-arthritic angles. The alignment technique aimed to preserve or restore constitutional alignment (CA) within predetermined limits, by defining a 'target zone' based on three criteria: 1) a ± 3° (range 87°-93°) primary tolerance for the femoral and tibial resections; 2) a ± 2° secondary tolerance for component obliquity, extending the bounds for FMA and TMA (range 85°-95°); 3) a planned HKA angle range of 175°-183°. Agreement between preoperative, planned and postoperative measurements of FMA, TMA and HKA angle were calculated using intra-class correlation coefficients (ICC).

RESULTS

Preoperative radiograph and CT-scan measurements revealed that, respectively, 73 (28%) and 103 (40%) knees were in the 'target zone', whereas postoperative radiographs revealed that 217 (84%) TKAs were in the 'target zone'. Deviation from the planned angles were - 0.5° ± 1.8° for FMA, - 0.5° ± 1.8° for TMA, and - 1.1° ± 2.1° for HKA angle. Finally, the agreement between the planned and achieved targets, indicated by ICC, were good for FMA (0.701), fair for TMA (0.462) and fair for HKA angle (0.472).

CONCLUSION

Using this strategy for coronal alignment, 84% of custom TKAs were within the 'target zone' for FMA, TMA and HKA angles. These findings support the concepts of emerging personalized medicine technologies, and emphasise the importance of accurate strategies for preoperative planning, which are key to achieving satisfactory 'personalised alignment' that can further be improved by customisation of implant components.

LEVEL OF EVIDENCE

IV.

Posterior Tibial Slope and a New Morphometric Method With Multiplanar Reconstruction Technique in a Turkish Sample

Aim: The posterior tibial slope (PTS) is important in planning many orthopedic procedures. The aim of the study is to outline a PTS measurement method using multiplanar reconstruction (MPR) in knee computed tomography (CT) images.

Methods: MPR reconstruction was performed on pre-captured CT angio images of 124 patients. A standard tibial axis was created. Then, using reference points, the PTS was measured separately for the medial PTS (MPTS) and lateral PTS (LPTS). To identify an intra- and interobserver error, the technical error of measurement (TEM), relative TEM (rTEM), and coefficient of reliability (R) of the measurement were analyzed.

Results: The study enrolled 124 patients (88 males, 36 females) from 18 to 92 years old. The average MPTS 8.63 ± 2.7° and LPTS 7.77 ± 3.1° were significantly different (p < 0.05). However, there was no difference between the sexes (p = 0.52 for MPTS; p = 0.9 for LPTS). The R for intraobserver reliability was 0.942 for the MPTS and 0.943 for the LPTS, and that for interobserver reliability was 0.815 and 0.806, respectively.

Conclusions: PTS measurement from CT images appears advantageous as it eliminates measurement limitations due to tibial rotation and has high intra- and interobserver consistency.

Morphometric study of gender difference in osteoarthritis posterior tibial slope using three-dimensional magnetic resonance imaging

Posterior tibial slope (PTS) is an important parameter of sagittal alignment associated with postoperative stability and kinematics after total knee arthroplasty (TKA). However, data are limited regarding the innate gender differences in PTS in Koreans. The current study separately measured the PTS of the medial and lateral tibial plateau on magnetic resonance images of 511 patients with knee joint osteoarthritis who had Kellgren and Lawrence grade 3 and 4 (430 women, 81 men) and compared the measurements between and within the genders. The tibia was then rotated to the tibial plateau with the tibial centroid axis and the PTS was evaluated from best-fit planes on the surface of the proximal tibia and individually for the medial, lateral, and overall plateaus. The average overall PTS was 10.0° ± 3.5°. The average overall PTS of the female and male patients was 10.2° ± 3.4° and 8.8° ± 4.0°, respectively. The average medial PTS was 10.4° ± 4.0°, significantly greater than the mean lateral PTS of 8.7° ± 3.9° (P < 0.05). The average medial and lateral tibial slopes for female patients were 10.7° ± 3.8° and 8.8° ± 3.8°, respectively, while the average medial and lateral tibial slopes for male patients were 8.9° ± 4.8° and 7.9° ± 4.7°, respectively. The medial and overall PTS were significantly greater in female patients than in male patients (P < 0.05). The results showed a gender difference in PTS and that medial PTS was greater than lateral PTS. These findings have clinical relevance in knee reconstructive surgery for determining ideal placement of the posterior slope tibial component. Surgeons should be aware of variability and gender differences in the tibial slope of patients undergoing TKA.

[Imaging and preoperative planning for osteotomies around the knee]

Physiologic alignment of the human lower leg is well defined. The etiology for malalignment comprises constitutional, degenerative and posttraumatic conditions. Osteotomies around the knee can correct the malalignment, provided that the origin of deviation is in proximity of the knee center. Crucial factors for the evaluation of axis deviation are the weight-bearing line, the mechanical axes of femur and tibia, the joint line angles and the center of the hip, knee and upper ankle joint. Careful preoperative planning is mandatory for reproducible clinical results. For the treatment of varus osteoarthritis of the knee, a slight overcorrection to the 62% width of the lateral tibial plateau is frequently advocated. In valgus knees, a correction of the postoperative weight-bearing line to physiologic conditions (44% of the lateral tibial width) is regarded to be sufficient. Recently, individualized planning of the correction angle is advocated to better address the underlying pathology of each patient.

Tibial plateau slopes in Indian patients with or without anterior cruciate ligament injury: a magnetic resonance imaging study

PURPOSE

To compare anterior cruciate ligament (ACL)-injured and ACL-intact patients as well as males and females in terms of tibial plateau slopes to determine their association with ACL injury.

METHODS

Magnetic resonance images (MRI) of the knee of 310 male and 179 female skeletally mature Indian patients (mean age, 40 years) with (n=170+29) or without (n=140+150) ACL injury were reviewed. Their medial and lateral tibial plateau slopes (MTPS and LTPS), medial tibial plateau depth (MTPD), and lateral tibial plateau height (LTPH) were measured using MRI.

RESULTS

The ACL-injured and ACL-intact groups were comparable in terms of MTPS (6.72º vs. 6.73º, p=0.07), LTPS (5.68º vs. 5.70º, p=0.09), MTD (1.74 vs. 1.73 mm, p=0.356), and LTH (2.21 vs. 2.22 mm, p=0.393). Males and females were also comparable in terms of MTPS and LTPS in both ACL-injured and ACL-intact groups.

CONCLUSION

ACL-injured and ACL-intact patients as well as males and females were comparable in terms of the tibial plateau slope parameters.

Computer-assisted total knee arthroplasty: impact of the surgeon's experience on the component placement

INTRODUCTION

Accuracy of implant positioning in total knee arthroplasty (TKA) has a major impact on postoperative outcomes. We investigate the accuracy of positioning of multiples values simultaneously in TKA navigated, even among novice users.

METHOD

The "novice" group included the first 91 knees operated on by 10 operators new to navigation and the "experienced" group 174 knees by an experienced navigator. Deviations from the preoperative planning were graded as optimal (≤3°), acceptable (4°-5°) or non-acceptable (≥5°). Moreover, the percentage of the three values fulfilling simultaneously the objective was calculated.

RESULTS

No significant difference in the number of non-acceptable results was found. The common objective for these three values was achieved within 5° in 96 % in the novice group and 98 % in the experienced one.

CONCLUSION

The satisfactory HKA alignment was not the result of reversed errors between the tibia and the femur, since it correlated the successful simultaneous results of alpha and beta angles.

Correlation between posterior offset of femoral condyles and sagittal slope of the tibial plateau

The aim of this study was to address, in normal knees, the variability of posterior offset of femoral condyles and tibial slope, and the presence of any correlation between the two that might be needed to achieve an adequate joint motion in flexion. Magnetic resonance images of normal knees of 80 subjects, 45 males and 35 females, with a mean age of 38.9 years, were analysed. Measurements were performed by two independent observers using an imaging visualization software. The tibial slope averaged 8 and 7.7 °, on the medial and lateral sides, respectively (P = 0.2); the mean posterior offset of femoral condyles was 27.4 and 25.2 mm on the two sides, respectively (P = 0.0001). The variation coefficient of the condylar offset and tibial slope was 11.5 and 38%, respectively. In the medial compartment, a significant correlation was found between the femoral condylar offset and the tibial slope, while the same was not observed in the lateral compartment of the knee. Magnetic resonance imaging allows the assessment of tibial slope and femoral condylar offset in the medial and lateral side separately, taking into account any difference between the two compartments. The sagittal tibial slope exhibits a greater variability compared with the posterior offset of femoral condyles. The correlation found, in the medial compartment, between the tibial slope and femoral condylar offset suggests that the reconstitution of the proper morphology of the posterior part of the knee joint may be necessary to obtain a full range of motion in flexion after total knee replacement.

Influence of cartilage and menisci on the sagittal slope of the tibial plateaus

We analyzed the magnetic resonance studies of the knee in 80 subjects, 45 men and 35 women with a mean age of 38.9 years, who showed no pathological condition of the joint. Using an imaging visualization software, the sagittal longitudinal axis of the tibia was identified. The angle between this axis and a line tangent to the bone profile of the tibial plateau (bone slope) and to the superior border of the menisci (meniscal slope) were calculated. Thickness of anterior and posterior portion of menisci and underlying cartilage were also measured. The bone slope averaged 8° and 7.7° on the medial and lateral sides, respectively. The mean meniscal slope was 4.1° and 3.3° on the medial and lateral sides, respectively, with a significant difference compared with the bone slope. Menisci and underlying cartilage were significantly thicker in their posterior than their anterior portion (7.6 and 5.2 mm, respectively, in the medial compartment; 8.6 and 5.2 mm, respectively, in the lateral compartment). The presence of cartilage and menisci implies a significant decrease in the posterior tibial slope. In the lateral compartment, the greater the bone slope, the larger the difference between bone and meniscal slope, which means that a marked posterior tilt of the lateral tibial plateau is decreased by the cartilage and meniscus. These findings should be taken into account in planning surgical procedures which affect the slope of the articular tibial surface.

Is noncontact ACL injury associated with the posterior tibial and meniscal slope?

BACKGROUND

The risk of noncontact ACL injury reportedly is increased in patients with a greater posterior tibial slope (PTS), but clinical data are inconsistent. It is unclear whether the medial and lateral PTSs have a different impact on this connection. It also is unknown whether the meniscal slope (MS) is associated with ACL injury.

PATIENTS/METHODS

Using MRI, we compared the medial and lateral PTSs and MSs separately in 55 matched pairs of patients with isolated noncontact ACL injuries and a control group.

RESULTS

Neither the PTS nor the relative difference between the medial and lateral PTSs differed between groups. In contrast, the lateral MS was greater with ACL injuries: 2.0° versus -2.7° in males with and without ACL injury and 1.7° versus -0.9 in females. Uninjured females had a greater PTS than males: 4.9° versus 3.0° in females and males medially, respectively; 5.7° versus 4.0° lateral.

CONCLUSIONS

There is no obvious link between the medial or lateral PTSs and ACL injury, and there is no obvious link between the relative difference in the medial and lateral PTSs and noncontact ACL injury. However, a greater lateral MS may indicate a greater risk of injury. The PTS can differ between the genders but the average difference is small.

LEVEL OF EVIDENCE

Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Novel measurement technique of the tibial slope on conventional MRI

The posterior inclination of the tibial plateau, which is referred to as posterior tibial slope, is determined routinely on lateral radiographs. However, radiographically, it is not always possible to reliably recognize the lateral plateau, making a separate assessment of the medial and lateral plateaus difficult. We propose a technique to measure the plateaus separately by defining a tibial longitudinal axis on a conventional MRI. The medial plateau posterior tibial slope obtained from radiographs was compared with MR images in 100 consecutive patients with knee pain when ligament or meniscal injury was assumed. The posterior tibial slope on MRI correlated with those on radiographs. The mean posterior tibial slope was 3.4 degrees smaller on MRI compared with radiographs (4.8 degrees +/- 2.4 degrees versus 8.2 degrees +/- 2.8 degrees , respectively). The reproducibility was slightly better on radiographs than MRI (+/- 0.9 degrees versus +/- 1.4 degrees ). Twenty-one of the 100 cases had more than a 5 degrees difference (range, -8.7 degrees to 8.9 degrees ) between the medial and lateral plateaus. The proposed technique allows measurement of the posterior tibial slope of the medial and lateral plateaus on a standard knee MRI. By using this novel measurement technique, a reliable assessment of the medial and lateral tibial plateaus is possible.

LEVEL OF EVIDENCE

Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Varus inclination of the proximal tibia or the distal femur does not influence high tibial osteotomy outcome

We have analysed retrospectively the influence of different sources of knee deformity on failure of closing wedge high tibial valgus osteotomy (HTO). Preoperative frontal plane varus deformities of the lower extremity, distal femur and proximal tibia, and medial convergence of the knee joint line were assessed on a standard whole leg radiograph in 76 patients. Using the logistic regression model, the probability of survival for HTO was 77% (SD 4%) at 10-years follow-up. Varus deformity of the lower extremity (< 175 degrees ), and medial convergence of the knee joint line (> 3 degrees ) were identified as preoperative risk factors for conversion to arthroplasty (P = 0.03 and P = 0.006). We found no evidence that varus inclination of the proximal tibia or distal femur influences long-term survival of HTO.