Increased lateral tibial posterior slope is related to tibial tunnel widening after primary ACL reconstruction.

PURPOSE: The purpose of the study was to determine the influence of femoral and tibial bone morphology on the amount of femoral and tibial tunnel widening after primary anatomic ACL reconstruction. It was hypothesized that tibial and femoral bone morphology would be significantly correlated with tunnel widening after anatomic ACL reconstruction. METHODS: Forty-nine consecutive patients (mean age 21.8 ± 8.1 years) who underwent primary single-bundle anatomic ACL reconstruction with hamstring autograft were enrolled. Two blinded observers measured the bone morphology of tibia and femur including, medial and lateral tibial posterior slope, medial and lateral tibial plateau width, medial and lateral femoral condyle width, femoral notch width, and bicondylar width on preoperative magnetic resonance imaging (MRI) scans. Tibial and femoral tunnel width at three points (aperture, mid-section, and exit) were measured on standard anteroposterior radiograph from 1 week and 1 year postoperatively (mean 12.5 ± 2 months). Tunnel width measurements at each point were compared between 1 week and 1 year to calculate percent of tunnel widening over time. Multivariable linear regression was used to analyze correlations between bone morphology and tunnel widening. RESULT: Increase in lateral tibial posterior slope was the only independent bony morphology characteristics that was significantly correlated with an increased tibial tunnel exit widening (R = 0.58). For every degree increase in lateral tibial posterior slope, a 3.2% increase in tibial tunnel exit width was predicted (p = 0.003). Excellent inter-observer and intra-observer reliability were determined for the measurements (ICC = 0.91 and 0.88, respectively). CONCLUSION: Increased lateral tibial posterior slope is an important preoperative anatomic factor that may predict tunnel widening at the tibial tunnel exit. In regard to clinical relevance, the results of this study suggest that lateral tibial posterior slope be measured preoperatively. In patients with increased lateral tibial posterior slope, more rigid graft fixation and a more conservative physical therapy regiment may be preferred. Level of evidence IV.

Increased lateral tibial slope predicts high-grade rotatory knee laxity pre-operatively in ACL reconstruction.

PURPOSE: To determine the influence of anatomical features of both the tibia and femur on quantitative pivot shift of anterior cruciate ligament (ACL)-injured patients. METHODS: Fifty-three consecutive ACL-injured patients (mean age 26 ± 10.1 years, 36 males) who underwent ACL reconstruction were prospectively enrolled. Two blinded observers measured the parameters of medial and lateral tibial slope, femoral condyle width, notch width, bicondylar width and tibial plateau width on magnetic resonance imaging. The same examiner performed pivot shift under anaesthesia, while a previously validated image analysis technique was used to quantify knee kinematics during examination. The median lateral compartment translation detected during pivot shift testing (2.8 mm) was used to classify patients into "low-grade rotatory laxity" (≤2.8 mm) and "high-grade rotatory laxity" (>2.8 mm) groups. RESULTS: Twenty-nine subjects were grouped as "low-grade rotatory laxity", and 24 subjects were grouped as "high-grade rotatory laxity". Of the tested bone morphologic parameters, lateral tibial plateau slope was significantly greater in "high-grade rotatory laxity" group (9.3° ± 3.4°) compared to "low-grade rotatory laxity" group (6.1° ± 3.7°) (p < 0.05). Lateral tibial plateau slope was a significant predictor of "high-grade rotatory laxity" (odds ratio 1.27, p < 0.05). A tibial slope of 9° and greater predicted "high-grade rotatory laxity" (sensitivity 63 %; specificity 72 %). CONCLUSION: Increased slope of the lateral tibial plateau might be an important anatomical variable predicting high-grade rotatory laxity in patients with ACL injury. The finding can be useful in the clinical setting in predicting potential non-copers to conservative therapy and aid in the individualization of the reconstructive procedures of patients. LEVEL OF EVIDENCE: Prospective diagnostic study, Level II.

Increased lateral femoral condyle ratio measured by MRI is associated with higher risk of solitary meniscus injury.

Background: Past studies found that an increased lateral femoral condyle ratio is associated with anterior cruciate ligament injuries, but it is not clear if there is a link between MRI-measured lateral femoral condyle ratios and meniscal injuries. MRI provides a more accurate selection of measurement planes. Compared to X-rays, it further reduces data errors due to non-standard positions. Objective: To study the relationship between knee bone morphology and Solitary meniscal injuries by MRI. Methods: A total of 175 patients were included in this retrospective case-control study, including 54 cases of pure medial meniscus injury, 44 cases of pure lateral meniscus injury as the experimental group, and 77 control subjects. MRI images were used to measure the femoral notch width, femoral condylar width, femoral notch width index, lateral femoral condylar ratio (LFCR), posterior tibial slope, medial tibial plateau depth, and meniscus slope. In addition, carefully check for the presence of specific signs such as bone contusions and meniscal extrusions. Comparing the anatomical differences in multiple bone morphologies between the two groups, a stepwise forward multifactorial logistic analysis was used to identify the risk factors for Solitary meniscal injuries. Finally, ROC curves were used to determine the critical values and best predictors of risk factors. Results: MTS, LTS, and LFCR ended up as independent risk factors for meniscus injury. Among all risk factors, LFCR had the largest AUC of 0.781 (0.714-0.848) with a threshold of 72.75%. When combined with MTS (>3.63°), diagnostic performance improved with an AUC of 0.833 (0.774-0.892). Conclusion: Steep medial tibial plateau slope, steep lateral tibial plateau slope angle, and deep posterior lateral femoral condyles on MRI are independent risk factors for meniscal injuries. In patients with knee discomfort with the above imaging findings (X-ray, MRI), we should suspect and carefully evaluate the occurrence of meniscal injuries. It not only provides a theoretical basis to understand the mechanism of meniscus injury but also provides theoretical guidance for the prevention of meniscus injury and the development of intervention measures. Level of evidence III.

Mechanical properties of multi-force vs. conventional NiTi archwires.

AIMS: Mechanical properties along the length of latest generation "multi-force" archwires were measured and compare with commercially available thermally activated and non-thermally activated nickel-titanium (NiTi) archwires. MATERIALS AND METHODS: A modified deflection test was used to produce load/deflection curves for different positions along the lengths of a sample of 114 NiTi archwires composed by thermal NiTi, non-thermal NiTi, two types of multi-force NiTi and one type of multi-force copper archwires of various cross-sections (0.016â€¯× 0.016 inch, 0.016â€¯× 0.022 inch, 0.018â€¯× 0.025 inch and 0.019â€¯× 0.025 inch). The length, slope and mean force expressed were calculated from the resulting unloading plateaus, enabling comparison between types of archwire at different points along their lengths. RESULTS: Among conventional thermal, conventional nonthermal and multiforce archwires, all parameters investigated were statistically different, whereby the performance of the latter was superior. Multi-force archwires displayed 27% and 31% lighter mean forces in the upper and lower arches, respectively, in addition to 62% and 40% reductions in unloading plateau slope and length, respectively, as compared to conventional CuNiTi wires. Comparison of the different types of multi-force wires tested revealed statistically significant differences in the three parameters, depending on the testing position but irrespective of their cross-section. CONCLUSIONS: Although conventional archwires display identical behaviour along their lengths, as advertised the multi-force archwires do indeed exert a progressive force which differs between anterior, medial and posterior sections. The multi-force wires provide lighter, more prolonged and constant forces than conventional wires without cross-section-dependent variation.

Eight-plate epiphysiodesis: are we creating an intra-articular deformity?

Aims: Guided growth using eight-plates is commonly used for correction of angular limb deformities in growing children. The principle is of tethering at the physeal periphery while enabling growth in the rest of the physis. The method is also applied for epiphysiodesis to correct limb-length discrepancy (LLD). Concerns have been raised regarding the potential of this method to create an epiphyseal deformity. However, this has not been investigated. The purpose of this study was to detect and quantify the occurrence of deformities in the proximal tibial epiphysis following treatment with eight-plates. Patients and Methods: A retrospective study was performed including 42 children at a mean age of 10.8 years (3.7 to 15.7) undergoing eight-plate insertion in the proximal tibia for correction of coronal plane deformities or LLD between 2007 and 2015. A total of 64 plates were inserted; 48 plates (34 patients) were inserted to correct angular deformities and 16 plates (8 patients) for LLD. Medical records, Picture Archive and Communication System images, and conventional radiographs were reviewed. Measurements included interscrew angle, lateral and medial plateau slope angles measured between the plateau surface and the line between the ends of the physis, and tibial plateau roof angle defined as 180° minus the sum of both plateau angles. Measurements were compared between radiographs performed adjacent to surgery and those at latest follow-up, and between operated and non-operated plateaus. Statistical analysis was performed using BMDP Statistical Software. Results: Slope angle increased in 31 (49.2%) of operated epiphyses by a mean of 5° (1° to 23°) compared with 29 (31.9%) in non-operated epiphyses (p = 0.043). Roof angle decreased in 29 (46.0%) of operated tibias and in 25 (27.5%) of non-operated ones by a mean of 5° (1° to 18°) (p = 0.028). Slope angle change frequency was similar in patients with LLD, varus and valgus correction (p = 0.37) but roof angle changes were slightly more frequent in LLD (p = 0.059) and correlated with the change in inter screw angles (r = 0.74, p = 0.001). Conclusion: The use of eight-plates in the proximal tibia for deformity correction and limb-length equalization causes a change in the bony morphology of the tibial plateau in a significant number of patients and the effect is more pronounced in the correction of LLD. Cite this article: Bone Joint J 2018;100-B:1112-16.