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ALLINEAMENTO DELLA COMPONENTE TIBIALE NELL'ARTROPROTESI DI GINOCCHIO EVITANDO ERRORI DI POSIZIONAMENTO CAUSATI DALLA TORSIONE TIBIALE
No full textINTRODUZIONE
Una delle possibili cause di errori di posizionamento della componente tibiale nelle protesi di ginocchio (PTG) quando viene utilizzata l’asta extramidollare, è insita nella morfologia tibiale che presenta una torsione longitudinale lungo il suo asse. E’stato evidenziato che a causa di ciò, l’epifisi distale della tibia è extraruotata rispetto a quella prossimale di circa 20-30° per cui se l’asta extramidollare vien posizionata nella cavigliera al centro della distanza intermalleolare, vi sono rischi elevati di posizionare la componente tibiale in varo. Utilizzando le strumentazioni standard vengono riportate percentuali di outliers (con allineamento in varo-valgo > di 3°) tra il 2% ed il 40%; tali percentuali sono state confermate anche in studi recenti che hanno riscontrato malallineamenti coronali in oltre il 20% dei casi. Al fine di bypassare questa problematica è stato suggerito di allineare l’asta extramidollare in linea con l’asse anteroposteriore (AP) dell’epifisi prossimale di tibia (asse tra l’inserzione tibiale del legamento crociato posteriore (LCP) ed il 1/3 mediale della tuberosità tibiale) lasciando l’asta extramidollare libera di ruotare alla caviglia, ossia senza allinearla a reperi anatomici definiti.
MATERIALI E METODI
Sono stati analizzati 120 pazienti (134 ginocchia) sottoposti a PTG con strumentario standard. I primi 65 pazienti (41 donne e 24 uomini con età media di 74,4 anni, per un totale di 72 ginocchia) (gruppo 1), sono stati trattati consecutivamente con tecnica standard mentre il secondo gruppo di 55 pazienti ( 32 donne e 23 uomini, con un età media di 71,6 anni, per un totale di 62 ginocchia) (gruppo 2), sono stati trattati consecutivamente con tecnica di allineamento dell’asta extramidollare solo prossimale. In particolare, nel primo gruppo l’asta extramidollare è stata allineata prossimalmente all’asse tibiale anteroposteriore (AP) precedentemente riportato e distalmente ad un punto situato 5 mm medialmente alla distanza intermalleolare; nel secondo gruppo l’asta extramidollare è stata allineata prossimalmente come nel primo gruppo mentre distalmente, in accordo alla nuova metodica utilizzata, non è stata allineata ad alcun repere anatomico ma lasciata libera di ruotare intorno alla cavigliera. Ciò comportava che l’asta extramidollare tendeva ad allinearsi verso il malleolo mediale nei pazienti con marcata torsione tibiale e verso il centro della distanza intermalleolare in quelli con torsione tibiale lieve. L’allineamento coronale della componente tibiale è stato valutato su radiografie in toto dell’arto inferiore effettuate 3-6 mesi dopo l’intervento. In particolare, è stato misurato l’angolo tra asse meccanico femoro-tibiale (angolo AMFT) e l’orientamento delle componenti rispetto all’asse meccanico. Un angolo tra asse meccanico femorale e tibiale compreso tra 0 e 3° ed un allineamento della componente tibiale o femorale compresi tra 0 e 3°, sono stati considerati nel range di normalità mentre tutti i pazienti in cui tali angoli superavano i 3° sono stati considerati come outliers. Il t-test ed il test di Fischer sono stati utilizzati per comparare gli angoli di allineamento nei 2 gruppi e i risultati clinici. L’intraclass correlation coefficient (ICC) è stato utilizzato per valutare l’accuratezza delle misurazioni tra osservatori e intra-osservatore.
RISULTATI
L’angolo AMFT è risultato essere 0.8° ± 1.7 nel gruppo 1 (range -3.2°- 6.8°) e 0.6° ± 1.8 nel gruppo 2 (range -2.3°- 6.1°) (n.s.). Un angolo AMFT nel range di normalità è stato riscontrato in 55 ginocchia ( 76% ) del gruppo 1 e in 53 (85%) del gruppo 2 (n.s.). L’allineamento della componente femorale rispetto all’asse meccanico è risultata essere in media 2.4° ± 1.8 nel gruppo 1 (range -3.3 – 6.5) e 1.8° ± 2 (range -2.6 – 5) nel gruppo 2 (n.s.). La percentuale di mal allineamenti nel piano coronale della componente femorale è risultata essere 26% (19 ginocchia) nel gruppo 1 e 27% (17 ginocchia) (ns). L’allineamento della componente tibiale sul piano coronale era in media -2.2° ± 1.7 nel gruppo 1 (range ¬-5.3° -2.2°) e - 0.7° ± 1.8 nel gruppo 2 (range -4°- 2.9°)(p=0.001). Un malallineamento in varo della componente tibiale è stato riscontrato in 16 ginocchia (22%) del gruppo 1 ed in 2 ( 3.2%) del gruppo 2 (p=0.001). Un malallineamento in valgo è stato riscontrato in 2 ginocchia (2.7%) del gruppo 1 ed in 2 (3.2%) del gruppo 2.
CONCLUSIONI
I risultati di questo studio hanno evidenziato che utilizzando una tecnica chirurgica in cui l’asta extramidollare venga allineata alla proiezione anteriore dell’asse meccanico tibiale solamente al livello prossimale, è possibile neutralizzare l’influenza della torsione tibiale sulla traslazione anteriore dell’asse meccanico e ridurre in questo modo la percentuale di malallineamenti in varo della componete tibiale.Background: A major issue in achieving a correct coronal alignment of tibial component in total knee arthroplasty (TKA) is tibial torsion, i.e., the axial rotation of the tibia along its longitudinal axis, which causes a rotational mismatch between proximal and distal epiphysis. It has been reported that, due to tibial torsion, the distal epiphysis is externally rotated compared to the proximal one by an average of 19°- 28°. This leads to a lateral shift of the anterior projection of the mechanical axis at the ankle joint compared to AP axes at the proximal tibia. As a result, if the extramedullary rod is not shifted medially at the ankle joint to compensate for tibial torsion a varus tibial cut is likely to occur.
Objectives: In this study we investigated the accuracy of a new surgical technique in which the influence of tibial torsion on the alignment of the tibial component is bypassed by positioning the extramedullary guide in line with the proximal tibia only.
Materials and methods: 120 patients (134 knees) who underwent TKA were analysed. 65 patients (41 women and 24 men with a mean age of 74.4 yrs, 72 knees) (group 1), were consecutively treated with standard technique while in the second group of 55 patients ( 32 women e 23 men, with a mean age of 71.6 yrs, 62 knees) (group 2), were consecutively treated with the proximal alignment technique. In particular, the extramedullary guide was set, at the proximal tibia, in line with an anterior projection of mechanical axis (AP axis) connecting the posterior tibial notch with the medial 1/3 of the tibial tuberosity (TT), in both groups. At the distal tibia, the extramedullary guide was set, in group 1, to a point located 5 mm medially to the center of the intermalleolar distance and, in group 2, in line with the proximal alignment on the TT, the extramedullary rod being locked in neutral alignment (varus-valgus = 0) in the malleolar clamp. The coronal alignment of tibial and femoral component was assessed by calculating the angle between their respective mechanical axes and a line tangent to the plateau of tibial component and to the distal condyles of femoral component, respectively. The measurements were repeated in the sagittal plane. A MFT angle of 0° ± 3° of varus (-) / valgus (+) and a component alignment of 0° ± 3° varus (-) / valgus (+), were considered within the normal range
Results: The MFT angle was 0.8° ± 1.7 in gr. 1 (range -3.2°- 6.8°) and 0.6° ± 1.8 in group 2 (range -2.3°- 6.1°) (n.s.). The MFT was within the normal range in 55 knees (76%) in group 1 and in 53 (85%) in group 2 (n.s.). The coronal alignment of the tibial component averaged -2.2° ± 1.7 in gr. 1 (range ¬-5.3° -2.2°) and - 0.7° ± 1.8 in group 2 (range -4°- 2.9°)(p=0.001). A varus malalignment of the tibial component was found in 16 knees (22%) in gr. 1 and in 2 in gr. 2 ( 3.2%) (p=0.001).
Conclusion: The accuracy of extramedullary instrumentation in achieving a proper coronal alignment of the tibial component may be affected by tibia torsion, which causes a lateral shift of the anterior projection of the mechanical axis at the ankle joint where the extramedullary rod should be aligned. Our results showed that the effects of tibial torsion on the alignment of extramedullary instrumentation may be neutralized by setting the extramedullary rod in line with the AP axis in the proximal tibia only. This technique was found to reduce the rate of malalignment of the tibial component
PRESERVAZIONE DEL LEGAMENTO CROCIATO POSTERIORE DURANTE IL TAGLIO TIBIALE NELL'ARTROPROTESI DI GINOCCHIO
No full textINTRODUZIONE
Una lesione iatrogena del LCP potrebbe spiegare il rollback paradosso che talvolta si può osservare nei pazienti con una protesi CR. Alcuni autori suggeriscono di delimitare con osteotomo un’isola cortico-spongiosa subito anteriormente al LCP. Tuttavia l’efficacia di tale tecnica non è dimostrata. L’utilizzo di una tecnica che prevede l’esecuzione di un doppio taglio si è dimostrata superiore sia in termini di migliore articolarità del ginocchio che di preservazione del normale rollback femorale rispetto alla tecnica standard.
Scopo di questo studio è stato valutare i risultati clinici e radiografici di un gruppo di pazienti operati di PTG in cui il taglio tibiale è stato eseguito con una tecnica alternativa atta a preservare l’inserzione del LCP.
METODI
Sono state analizzate due serie consecutive di pazienti sottoposti a PTG. Nella prima il taglio tibiale è stato eseguito “in blocco” (50 pazienti, gruppo di controllo). Nella seconda (50 pazienti, gruppo di studio) il taglio tibiale è stato eseguito in 2 tempi, ossia è stato effettuato un primo taglio dello spessore di 5 mm fino alla corticale tibiale posteriore atto a preservare l’inserzione del LCP, ed un secondo taglio di altri 5 mm per ottenere lo spessore adeguato all’impianto della componente tibiale. Tutti i pazienti sono stati sottoposti a controllo clinico con il KSS e radiografico a 3,6 e 12 mesi dopo l’intervento.
RISULTATI
A 3 e 6 mesi dall’intervento, il KSS era di 70 e 79, rispettivamente nel gr.controllo e 69 e 81 nel gr.di studio (p>0.05); a 12 mesi dall’intervento era 91 e 93,5, rispettivamente (p=0.05). L’articolarità del ginocchio all’ultimo follow-up è risultata in media di 111° nel gruppo controllo e 119° in quello di studio (p=0.04). L’esame radiografico standard eseguito nella massima flessione del ginocchio ha evidenziato un rollback chiaramente ridotto in 18 pazienti (36%) del gruppo controllo ed in 3 (6%) di quelli del gruppo di studio (p=0.0001).
CONCLUSIONI
Per ridurre i rischi di lesionare il LCP nelle protesi di ginocchio CR, è possibile effettuare un doppio taglio tibiale, il primo di uno spessore tale da preservare con certezza il LCP ed il secondo per raggiungere i 9-10mm necessari per l’impianto della componente tibiale
DIFFERENZE TRA STELI RETTI CON ESTESO RIVESTIMENTO IN IDROSSIAPATITE E POSSIBILI IMPLICAZIONI CLINICHE
No full textRecentemente sono stati introdotti diversi steli femorali apparentemente alquanto simili per geometria e per estensione del rivestimento in idrossiapatite (HA). Lo scopo di questo studio è stato di valutare le caratteristiche geometriche di 5 di questi steli per verificare se possono essere utilizzati in modo intercambiabile o se, invece, dovrebbero essere utilizzati con indicazioni differenti.
MATERIALI E METODI Sono stati analizzati i diametri coronali e sagittali a livello prossimale (calcar), intermedio e distale (1cm prossimale al tip dello stelo) in tutte le taglie di 5 steli apparentemente simili, ossia lo stelo Corail (Depuy), Avenir Mueller (Zimmer), Polarstem (Smith&Nephiew), Trendhip (Aesculap) e H-max (Lima). Di ciascuno stelo è stato poi calcolato il “Flare-Index” (FI) ed il “Tapered- index” ossia il rapporto tra il diametro prossimale e distale e tra l’area dello stelo calcolata su un taglio assiale a livello prossimale e distale, rispettivamente. Per l’analisi statistica sono stati utilizzati tests non parametrici (Kruskan-Wallis e il Mann-Whitney).
RISULTATI
La lunghezza dello stelo è risultata variare tra 115 (Corail) e 134 mm (Trendhip) nella taglia più piccola e tra 169 (Trendhip) e 190mm (Corail) in quella più grande. L’angolo meta-diafisario è risultato variare tra 163° e 171°. L’analisi statistica ha evidenziato una differenza significativa (p=0.001) tra il diametro coronale prossimale dei vari steli mentre i diametri sagittali non hanno evidenziato differenze significative. Una differenza significativa è stata anche riscontrata tra i vari steli nel flare-index ed il tapered-index (p=0.003 e p=0.001).
DISCUSSIONE
I risultati hanno evidenziato che esistono differenze geometriche significative tra i vari steli analizzati per cui alcuni di questi steli hanno una forma decisamente più a cuneo di altri. Questi risultati suggeriscono che nei femori di tipo A di Dorr, sarebbe preferibile utilizzare uno stelo con un tapered index più elevato in modo da evitare una fissazione prevalentemente diafisaria, mentre l’opposto, ossia uno stelo con basso tapered index, dovrebbe essere preferito nei femori di tipo C.
CONCLUSIONI
Gli steli in titanio con esteso rivestimento in HA tipo Corail, per quanto simili in apparenza, presentano significative differenze nella loro geometria. La conoscenza di tali differenze può essere di aiuto al chirurgo nello scegliere lo stelo più idoneo alla morfologia del femore da operare.Background
Several tapered stems with similar geometry and extensive hydroxyapatite coating have recently been introduced. It is not clear, however, whether they share the same design or whether exhibit any difference that might affect their clinical performances.
Hypothesis
We analysed 5 look-alike tapered titanium femoral stem with extensive hydroxyapatite coating to establish whether they exhibit similar geometric features and may therefore be used indifferently when a cementless stem is indicated.
Methods
Fifty stems of 5 different brands were analysed. Measurements including stem length, coronal and sagittal diameters, length stem shoulder and meta-diaphyseal angle were performed on digitalized templates. The ratio between the proximal and distal coronal diameters of the stems and that between the proximal and distal cross-sectional area were calculated as a flare index and tapered index, respectively. Measurements were compared on all available sizes of each brand and on selected comparable sizes showing a similar coronal diameter in the middle portion of the stem.
Results
The coronal and sagittal diameters between brands differed up to 4.4 mm and 3.3 mm, respectively. A significant difference between stems of different brands was found in the flare index and tapered indexes when either all available sizes or only comparable sizes were analysed. A significant difference was also found among the different brands in the length of stem shoulder and in the meta-diaphyseal angle.
Conclusions
Look-alike tapered stems should not be used indifferently since they may actually exhibit different geometric features potentially affecting their clinical performances
RISULTATI PRELIMINARI DI UNA PROTESI DI GINOCCHIO POSTEROSTABILIZZATA CON DISEGNO POST-CAM PER OTTIMIZZARE IL ROLLBACK FEMORALE
No full textDiversi studi hanno evidenziato che la maggioranza dei pazienti operati di artroprotesi di ginocchio riporta risultati clinici soddisfacenti a lungo termine. Tuttavia recentemente è anche emerso che una percentuale di circa il 20-30% dei pazienti operati presenta una ripresa funzionale incompleta e riferisce uno scarso miglioramento dopo l’intervento. Una delle possibili cause di insuccesso della protesi di ginocchio è il mancato recupero della normale biomeccanica articolare per cui il rollback femorale è insufficiente, eccessivo o comunque non avviene con un pivot mediale come nella norma. In questo studio vengono riportati i risultati clinici e radiografici di una nuova protesi di ginocchio postero stabilizzata dotata di sistema post-cam disegnato per produrre un rollback femorale più rispettoso della normale biomeccanica articolare.
MATERIALE E METODI
E’ stata analizzata prospettivamente una serie di 45 pazienti sottoposti ad artroprotesi di ginocchio PS cementata. La serie era composta da 31 donne e 14 uomini con un’età media di 76 anni (range 68-91 anni).
L’impianto utilizzato prevede un sistema post-cam asimmetrico che limita il rollback mediale mantenendo invariato quello laterale con lo scopo di garantire un pivotal motion mediale che si avvicini più possibile a quello del ginocchio normale. Dopo l’intervento i pazienti sono stati controllati clinicamente con il KSS e la VAS e radiograficamente con rdx standard e nella massima flessione, dopo 2,6 e 12 mesi dall’intervento.
RISULTATI
IL KSS e la VAS preoperatorie erano in media 37,4 e 8.3, rispettivamente. A 3 e 6 mesi dall’intervento, il KSS era di 75 e 84, rispettivamente; a 12 mesi dall’intervento era 95.2. La VAS media era 5.1 e 3,7 a 3 e 6 mesi ripspettivamente e 2.8 a 12 mesi dall’intervento, con un miglioramento statisticamente significativo ad ogni controllo. L’articolarità del ginocchio all’ultimo follow-up è risultata in media di 122° . L’esame radiografico eseguito nella massima flessione del ginocchio ha evidenziato un rollback apparentemente fisiologico in tutti i pazienti.
DISCUSSIONE
Sebbene diversi modelli di artroprotesi di ginocchio abbiano riportato risultati soddisfacenti in termine di ripresa funzionale e risoluzione della sintomatologia dolorosa, il ripristino di una normale biomeccanica articolare è ancora obbiettivo difficilmente raggiunto in molti pazienti operati. In alcuni casi la presenza di un rollback paradosso o comunque inadeguato è causa di dolore o limitazione articolare nella flessione del ginocchio. In questo studio sono stati analizzati i risultati preliminari di un nuovo modello di protesi posterostabilizzata con sistema post-cam atto a produrre un rollback asimmetrico più fisiologico rispetto a quello delle artroprotesi in commercio. I risultati di questo studio in una serie preliminare di pazienti hanno evienziato che tale impianto sembra garantire un’ottima articolarità in flessione già dai primi mesi dell’intervento, con un rollback femorale apparentemente conservato.
CONCLUSIONI
I risultati preliminari a breve termine di un limitato gruppo di pazienti in cui è stata impiantata un’artroprotesi di ginocchio dotata di un peculiare sistema post-cam atto a garantire un rollback prevalentemente laterale, sono stati incoraggianti dal punto di vista clinico-funzionale. Studi a medio-lungo termine dovranno analizzare i potenziali vantaggi di tale nuovo disegno di portesi rispetto ad una protesi postero-stabilizzata convenzionale
Are Tapered Titanium Stems With A Similar Geometry And Hydroxyapatite Coating Extension All The Same?
No full textBackground
Several studies have shown that Corail stem provides high rates of satisfactory clinical results at long term follow-ups. Early concerns were possible complications related to such extensive HA coating, including HA resorption, delamination, osteolysis and early wear (1,2), as well as the risk of subsidence in collarless stems (3). However, long-term results have shown that the risk of coating-related complications is low (4-6), while stem subsidence may occur with different effects on the clinical outcome (7-10). In view of the long-term survival rate of the original stem, several tapered titanium femoral stem with extensive hydroxyapatite coating (TTSs-EHAC) have been introduced on the market in recent years. These stems resemble the original one in terms of geometry and extension of the HA coating, with no apparent differences between them.
Objectives
The purpose of this study was to compare the geometry of the original TTS-EHAC with that of 4 similar stems recently introduced; our hypothesis was that these new stems, despite appearing to duplicate the original one, actually have a different geometry that may affect their clinical indications. Study design and method: The coronal and sagittal geometry of the original Corail (CO) (DePuy, Johnson & Johnson, USA) and of four similar TTSs-EHAC, i.e. Trendhip (TH) (B.Braun-Aesculap, Germany), H-Max (HM) (Lima Corporate, Italy), Polarstem (PS) (Smith & Nephew, USA) and Avenir Muller (AM) (Zimmer, USA), were analysed (Fig.1). The assessment of the stem geometry included the measurement of the medio-lateral and antero-posterior diameters in the coronal and sagittal planes at the level of the proximal-medial extension of the HA coating, 10 mm proximally to the distal tip and in the middle between the two points (Fig 2). The total length of the stem, the length of the stem shoulder, defined as the tilted portion of the proximal and lateral side of the stem and the angle between a line tangent to the stem shoulder and the diaphyseal portion of the stem (meta-diaphyseal angle), were analysed (Fig. 2). The flare index (FI) of the stem was defined as the ratio between the coronal diameter of the stem measured at the level of the proximal-medial extension of the HA coating (A diameter, Fig. 2) and the coronal diameter measured 1 cm proximal to the tip of the stem (C diameter, Fig.2). The tapered index (TI) was calculated as the ratio between the cross-sectional area measured at the level of the proximal-medial extension of the HA coating and the cross-sectional area measured 1 cm proximal to the tip of the stem (Fig. 2). To assess any differences in stem geometry between brands, the coronal and sagittal diameters, flare indexes and tapered indexes were compared in all the sizes available for each brand as well as in the subgroup of comparable size. Measurements were performed on all the sizes of each brand on digitalized images of stem templates provided by the manufactures using AUTOCAD software Statistical analysis included Kruskal-Wallis and Mann-Whitney tests to detect any differences between the coronal and sagittal diameters, flare index and tapered index between stems of the five brands.
Results: When all the sizes of the various brands were considered, a significant difference was found in the overall flare index and tapered index (p= 0.001 and p<0.001, respectively) while coronal and sagittal diameters, per se, were not different with the exception of the proximal coronal diameter which was significantly different in HM and AM (p=0.04).
Comparable Sizes
Six classes of sizes for each of the 5 brands (30 stems) yielded a comparable diameter in the middle portion of the stem (B diameter). The differences in B-diameter between the stems of each class of comparable sizes averaged 0.8 mm (range 0.5-1.3mm). A significant difference was found in the flare index (p=0.01) and tapered index (p=0.002) of comparable sizes between the different brands (Fig. 3). A significant difference was detected between the 5 brands in the length of stem shoulder (p=0.04). The meta-diaphyseal angle ranged between 163° and 171° (p<0.001). Conclusion: Several TTSs-EHC have recently been introduced on the market. Their geometry is similar and includes a tapered shape with a quadrangular cross section and a proximal flared portion in both planes. Horizontal and vertical groves are present on the porous coating, which is entirely covered with HA to enhance mechanical stability. As these stems closely resemble each other and no investigation has previously been conducted to detect any differences between them, it might be assumed that any one of these stems can be used indifferently whenever a cementless stem is indicated. Our results have shown that the flare index and tapered index yielded a significant difference when all the brands were considered; when each stem was matched with the others, the difference in flare index was still significant between HM and all the remaining stems except PS. The tapered index, which takes into account the ratio between the proximal and distal cross-sectional areas of the stem, differed significantly both when all brands were analysed together and when each stem was compared with the others. As the number of sizes of the five brands ranges between 8 and 11, to compare stems of similar size, we selected 30 stems, 6 for each brand, with a similar coronal diameter in the middle portion of the stem. The analysis of these 30 stems showed that both the flare index and tapered indexes differ significantly among the 5 stems analysed. These findings indicate that some of these stems exhibit a significantly more pronounced funnel shape than others, thus suggesting that their biomechanical behavior may vary in different morphologies of the proximal femur.
We suggest that these stems are not used indifferently in any patient in whom a cementless stem is indicated but rather on the basis of a pre-operative planning in which the stem showing the best fit and fill is selected
Improving Sagittal Alignment Of Tibial Component In TKA With Extramedullary Instrumentation
No full textOBJECTIVE
The sagittal slope of the tibial component may be implicated in the clinical performances and longevity of total knee arthroplasty (TKA). Extramedullary instrumentations are widely used in TKA. A few investigations suggested that the proximal portion of tibial crest and fibular diaphyseal axis are closely parallel to the tibial mechanical axis in the sagittal plane. However, to what extent these anatomical references may guide the surgeon to achieve a proper sagittal alignment of tibial component has yet to be established. The object of this study was to analyse the relationship between an extramedullary instrumentation, positioned parallel to the sagittal mechanical axis, and the anterior tibial profile and to establish whether two or more portions in the anterior tibial profile may be identified to place the extramedullary rod parallel to the sagittal mechanical axis.
MATERIALS AND METHODS
Fifty cadaveric dried tibiae of Caucasian individuals were analyzed. A standard intramedullary rod used to perform the tibial cut in TKA was inserted into the medullary canal as reference for the mecanichal axis of the tibia in the sagittal plane. A standard tibial cutting block used for TKA was connected to the intramedullary rod and set at 0° varus/valgus and 0° sagittal slope. The tibial cutting block was secured with 2 pins to the proximal part of the tibia 10 mm from the tibial plateau, to simulate a standard tibial cut. An extramedullary rod was then inserted into the tibial cutting block to evaluate its relationship with the entire anterior tibial profile. A standard lateral radiograph was taken having placed each tibia with its antero-posterior axis parallel to the horizontal plane to obtain a correct lateral view radiograph. When the extramedullary rod was not parallel to the intramedullary one, it was adjusted on the cutting block until the two rods were parallel each other. The distance between the anterior profile of the tibia and the extramedullary rod was assesses using AUTOCAD software at points located every 10 mm. A mathematical model was then applied to take into account the different tibial length and to measure the distance between the anterior tibial border and the extramedullary rod at interval of 2% of the entire tibial length. This generated 38 measurements along the anterior border of for each tibia, included between 20% and 95% of the whole tibial length from the tibial plateau to the distal metaphysis. A paired t-test (significance p<0.05) was used to assess the difference in the distance from the anterior tibial border and the extramedullary rod between different points of the anterior tibial border.
RESULTS
Three tibiae showing a sagittal deformity which caused a malalignment of the intramedullary rod with respect to the sagittal mechanical axis were excluded, leaving 47 tibiae eligible for the study. The average tibial length was 31.98 mm (range 28.28-37.5mm, SD 2.3). The distance from the anterior tibial border and the extramedullary rod showed a non-linear distribution, the lower values being found at 20% of the tibial length and the higher between 70% and 80% of the tibial length. Between 80% and 90% of the tibial length, the distance between the anterior tibial border and the extramedullary rod decreased but it was still significantly greater than in the proximal tibia. The anterior tibial border showed much less variability among individuals in the proximal diaphysis than in the middle-distal diaphysis and distal metaphysis.
CONCLUSIONS
Although the anterior profile of tibial border is commonly used as intraoperative reference for the sagittal alignment of the tibial component, to our knowledge no study has analysed its relationship with the mechanical axis, along the whole tibial length. This study has shown that when the extramedullary rod is placed at the same distance from the anterior tibial border at 2 points located at 56% and 90% of the tibial length , the extramedullary rod is likely to be aligned with the sagittal mechanical axis
A passive exoskeleton can push your life up: Application on multiple sclerosis patients
No full textIn the present study, we report the benefits of a passive and fully articulated exoskeleton on multiple sclerosis patients by means of behavioral and electrophysiological measures, paying particular attention to the prefrontal cortex activity. Multiple sclerosis is a neurological condition characterized by lesions of the myelin sheaths that encapsulate the neurons of the brain, spine and optic nerve, and it causes transient or progressive symptoms and impairments in gait and posture. Up to 50% of multiple sclerosis patients require walking aids and 10% are wheelchair-bound 15 years following the initial diagnosis. We tested the ability of a new orthosis, the “Human Body Posturizer”, designed to improve the structural and functional symmetry of the body through proprioception, in multiple sclerosis patients. We observed that a single Human Body Posturizer application improved mobility, ambulation and response accuracy, in all of the tested patients. Most importantly, we associated these clinical observations and behavioral effects to changes in brain activity, particularly in the prefrontal cortex
Higher rates of fully preserved posterior cruciate ligament in total knee arthroplasty using a double tibial cut: a prospective randomized controlled trial
Full text linkPurposeIn cruciate retaining total knee arthroplasty, posterior cruciate ligament damage may occur during tibial cutting. A prospective randomized study was conducted to investigate whether a novel tibial cutting technique was more effective than the currently used techniques.Materials and methodsPatients undergoing cruciate retaining total knee arthroplasty were recruited in a prospective, randomized, controlled trial. In 25 patients (group 1) the tibial cut was performed using a double tibial cut technique; in 25 (group 2) and 25 (group 3) patients, the bone island and en bloc resection techniques were performed, respectively. Posterior cruciate ligament integrity and femoral rollback were assessed at the end of surgery. The Oxford Knee Score, WOMAC score and range of motion were assessed postoperatively.ResultsPosterior cruciate ligament was completely preserved in 92% of patients in group 1 and in 64% in group 2 and 3, respectively (p = 0.03). The Oxford Knee Score and WOMAC scores did not differ between groups (p = 0.4). The mean knee flexion was 126.4 degrees, 121.5 degrees and 123.9 degrees in groups 1, 2 and 3, respectively (p = 0.04). The femoral rollback at 120 degrees flexion was 80.7%, 72.2% and 75.4% in groups 1, 2 and 3, respectively (p = 0.01).ConclusionsThe double cut technique preserves the posterior cruciate ligament at significantly higher rates than the bone island or en bloc resection techniques. Better posterior cruciate ligament preservation may improve the femoral rollback and knee flexion.Level of evidenceProspective randomized controlled trial, Level I
Preserving the PCL during the tibial cut in total knee arthroplasty
No full textPurpose
Previous studies have shown that the PCL insertion may be damaged during the tibial cut performed in total knee arthroplasty. We investigated the maximum thickness of a tibial cut that preserves the PCL insertion and to what extent the posterior slope of the tibial cut and that of the patient’s tibial plateaus affect the outcome.
Methods
MR images of 83 knees were analysed. The maximum thickness of a tibial cut that preserves the PCL using a posterior slope of 0°, 3°, 5° and parallel to the patient’s slope of the tibial plateau, was evaluated. Correlations between the results and the degrees of the posterior slope of the patient’s tibial plateaus were also investigated.
Results
The maximum thickness of a tibial cut that preserves the entire PCL insertion was, on average, 5.5, 4.7, 4.2 and 3.1 mm when a posterior slope of 0°, 3°, 5° and parallel to the patients’ tibial plateaus was used, respectively. When the 25th percentile was considered, the maximum thickness of a tibial cut that preserved the PCL was 4 and 3 mm with a tibial cut of 0° and 5° of posterior slope, respectively. The maximum thickness of a tibial cut that preserved the PCL was significantly greater in patients with a sagittal slope of the tibial plateaus more than 8° than in those with a sagittal slope less than 8°.
Conclusion
In cruciate retaining implants, the PCL insertion may be spared in the majority of patients by performing a tibial cut of 4 mm, or even less when a posterior slope of 3°–5° is used. The clinical relevance of our study is that the execution of a conservative tibial cut, followed by a second tibial resection to achieve the thickness required for the tibial component to be implanted, may be an alternative technique to spare the PCL in CR TKA.
Level of evidence
II
Tibial component alignment in total knee arthroplasty may improve by setting extra-medullary instrumentation to the proximal tibia only
No full textCurrent instrumentations in TKA is not entirely satisfactory since a varus malalignment of tibial component has been reported in 2% to 40% of cases. This result may partially be due to tibial torsion, which cause a lateral shift of the anterior projection of the mechanical axis at the ankle joint compared to a-p axis of proximal tibia. In this study we investigated the accuracy of a new surgical technique in which the influence of tibial torsion on the alignment of the tibial component is bypassed by positioning the extramedullary rod in line with the proximal tibia only, with no references at the ankle joint.
MATERIALS AND METHODS: Eighty-six consecutive patients (94 knees) who underwent conventional TKA were included in the study. The extramedullary guide for the tibial cut was set at the proximal tibia, in line with an anterior projection of mechanical axis connecting the posterior tibial notch with the medial 1/3 of the tibial tuberosity in both groups. At the distal tibia, extramedullary rod was set, in the first 47 knees (group 1), to a point located 5 mm medially to the center of the intermalleolar distance, while in the second 47 knees (group 2), it was left free to rotate in the axial plane according to the proximal tibial alignment. Mechanical femorotibial angle(MFT) and tibial component alignment was assessed postoperatively on long standing radiographs.
RESULTS: The mean MFT angle was 3.4°± 1.9 in group 1 (range -3° to 7°; 95% CI, 2.9°- 3.8) and 2.7° ± 1.8 in group 2 (range -2° to 6.5°; 95% CI, 2.2 - 3.1) (p=0.07). A MFT angle in the normal range was found in 36 knees (77%) in group 1 and 40 (85%) in group 2 (p=0.2). A malalignment of the tibial component >3° in the coronal plane was present in 16 knees of group 1 (34%); in 2 of them it was greater than 4°. In group 2, two knees showed a malalignment of the tibial component>3° (4%) (p=0.0001 vs group 1), none of whom greater than 4°.
DISCUSSION: A major issue in achieving a correct coronal alignment of tibial component in TKA is tibial torsion, which causes a rotational mismatch between proximal and distal epiphysis . If the extramedullary rod is not translated medially at the ankle joint to compensate for tibial torsion, a varus tibial cut is likely to occur. In keeping with this, a varus malalignment of the tibial component is the most frequent error found when extramedullary systems are used .
CONCLUSIONS: Our results demonstrated that malalignment of tibial component in coronal plane may be reduce using a surgical technique in which he possible effects of tibial torsion are bypassed setting the extramedullary rod in line with proximal tibial references only
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