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° smaller on MRI compared with radiographs (4.8° ± 2.4° versus 8.2° ± 2.8°, respectively). The reproducibility was slightly better on radiographs than MRI (± 0.9° versus ± 1.4°). Twenty-one of the 100 cases had more than a 5° difference (range, −8.7° to 8.9°) 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.

/pdf/novel-measurement-technique-of-the-tibial-slope-on-194q95nvb6.pdf

Novel measurement technique of the tibial slope on conventional MRI.

Introduction Few data exist regarding the outcome and survivorship of medial UKA in patients with minor varus alignment. The purpose of this study was therefore to analyse the clinical results of medial UKA implanted with no more than 7° of varus, and to verify whether there was a relationship between limb alignment and overall outcomes. Material and methods One hundred and twenty five medial fixed-bearing UKAs with no more than 7° of varus were retrospectively analysed. The varus/valgus inclination and thickness of the bone cuts were performed relating to the proximal tibial epiphyseal axis. Patients were assessed with the IKS scores and range of knee motion. The subjects were classified into three groups according to the postoperative femoro-tibial mechanical alignment angle (group A: −2° to 1°; group B: 2° to 4°; group C: 5° to 7°). Results The mean follow-up was 7.6years (range, 3.5–9.3). IKS knee scores increased proportionally with increasing varus according to a linear relationship ( p ≪0.01). Additionally, IKS knee scores were significantly higher in group B and still higher in group C if compared to those in group A ( p =0.003). Finally, a significantly higher frequency of IKS function scores>90 points in subjects with femoro-tibial mechanical alignment angle≥4° was found ( p =0.009). Conclusions Minor varus alignment does not compromise the mid- to long-term outcome of a medial UKA, and gives better results compared to neutral or close-to-neutral alignment. Level of evidence IV — Retrospective case series study.

Minor varus alignment provides better results than neutral alignment in medial UKA

Background:There are currently limited human in vivo data characterizing the role of the meniscus in load distribution within the tibiofemoral joint.Purpose/Hypothesis:The purpose was to compare th...

/pdf/in-vivo-tibial-cartilage-strains-in-regions-of-cartilage-to-1yjqy45s6r.pdf

In Vivo Tibial Cartilage Strains in Regions of Cartilage-to-Cartilage Contact and Cartilage-to-Meniscus Contact in Response to Walking.

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). 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). 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). 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. IV.

/pdf/custom-total-knee-arthroplasty-facilitates-restoration-of-1g7f3xsu8i.pdf

Custom total knee arthroplasty facilitates restoration of constitutional coronal alignment.

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 ( 3°) 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.

/pdf/varus-inclination-of-the-proximal-tibia-or-the-distal-femur-zb4klz2wop.pdf

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

Resume La mesure radiographique de l’axe epiphysaire proximal du tibia mise au point par Levigne a ete proposee pour differencier le varus tibial constitutionnel de l’usure osseuse. Les auteurs ont etudie la reproductibilite intra- et inter-observateur d’une telle mesure. Cinquante cliches telemetriques du membre inferieur de face ont ete realises chez 50 patients volontaires, indemnes de toute pathologie connue du genou, choisis au hasard dans une population d’operes du membre superieur. Quatre series de mesures independantes ont ete realisees par trois operateurs differents. La reproductibilite intra- et inter-observateur a ete etudiee par le calcul du coefficient de correlation intraclasse ρ.L’axe epiphysaire proximal n’a pu etre determine sur 7 a 18 des 50 cliches selon les operateurs. Les 3 observateurs n’ont ete capables de realiser toutes les mesures que pour 25 patients seulement. La reproductibilite intra-observateur etait consideree comme bonne (ρ = 0,62). La reproductibilite inter-observateur etait consideree comme moyenne (ρ = 0,41). La technique de Levigne ne semble pas pouvoir etre utilisee de facon fiable pour definir des indications chirurgicales differentes selon la morphologie de l’extremite proximale du tibia.

Difficultés et reproductibilité de la mesure radiographique de l’axe épiphysaire proximal du tibia selon la technique de Lévigne

Purpose: Knowledge of the radiological axes in the normal lower limb is important for correction and reconstruction surgery. Classically, the femorotibial mechanical axis presents a zero angle on the anteroposterior view, with 3° femoral valgus being compensated by an equivalent tibial varus. Reference data have however been established with questionable methodology because they have been obtained with small selected samples. Material and methods: We obtained teleradiograms of the lower limbs in 100 healthy volunteers free of any disease of the lower limbs and selected randomly among patients undergoing surgery for trauma or degenerative lesions of the upper limb. The following angles were measured by the same senior surgeon: mechanical femorotibial angle, orientation of the femoral condylar complex in relation to the mechanical axis of the femur, angle between the mechanial axis and the anatomic axis of the femur, orientation of the tibial plateaux in relation to the mechanical axis of the tibia. Results: Sixty-nine men and 31 woman, mean age 39 years (range 17 – 62 years) participated in this study. The mean mechanical femorotibial angle was 179° (SD 3°, median 179°, range 168°–185°). The mean orientation of the femoral condylar complex in relation to the femoral mechanical axis was 91° (SD 2°, median 91°, range 86°–98°); 17 subjects had the classical value of 93°. The mean angle between the mechanical and anatomic axis of the femur was 6° (SD 1°, median 6°, range 3°–9°); 29 subjects had the classical value of 7°. The mean orientation of the tibial plateaux in relation to the mechanical axis of the tibia was 88° (SD 2°, median 88°, range 82°–84°); 14 subjects had the classical value of 87°. Discussion and conclusion: The values considered to be normal in the literature only included 15–20% of the subjects in this study. Although there could be a theoretical selection bias in this series, it can be assumed that there is a wide dispersion of “normal” values around the means. The pertinence of this dispersion in clinical practice remains to be established. The question of individualising reconstruction or prosthetic procedures is raised.

Radiological assessment of lower limb alignment in the normal subjet: angles observed in 100 healthy subjects

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Difficultés et reproductibilité de la mesure radiographique de l’axe épiphysaire proximal du tibia selon la technique de Lévigne

Radiological assessment of lower limb alignment in the normal subjet: angles observed in 100 healthy subjects