A Biomechanical Analysis of Peroneus Brevis Split Lesions, Repair, and Partial Resection

BACKGROUND Peroneus brevis tendon tears are associated with chronic ankle pain and instability following sprain injuries. The aim of this study is to elucidate the biomechanical changes induced by a peroneus brevis split and surgical treatment by tubularizing suture or partial resection. METHODS Nine human lower leg specimens were biomechanically tested. Preexisting tendon pathology was ruled out by magnetic resonance imaging and histology. Specimens were subjected to sequential testing of 4 conditions of the peroneus brevis tendon: (1) native, (2) longitudinal lesion, (3) tubularizing suture, and (4) 50% resection. The outcome parameters were the tendon stiffness (N/mm) and the length variation of the split portion at 5 N load. RESULTS The median specimen age at death was 55.8 years (range 50-64 years). The longitudinal tendon split led to an elongation by 1.21 ± 1.15 mm, which was significantly reduced by tubularizing suture to 0.24 ± 0.97 mm (P = .021). Furthermore, 50% resection of the tendon elongated it by a mean 2.45 ± 1.9 mm (P = .01) and significantly reduced its stiffness compared to the intact condition (4.7 ± 1.17 N/mm, P = .024) and sutured condition (4.76 ± 1.04 N/mm, P = .011). CONCLUSION Longitudinal split and 50% resection of the peroneus brevis tendon led to elongation and loss of tendon stiffness. These properties were improved by tubularizing suture. The significance of these changes in the clinical setting needs further investigation. CLINICAL RELEVANCE Tubularizing suture of a peroneus brevis split can restore biomechanical properties to almost native condition, potentially aiding ankle stability in symptomatic cases. A split lesion and partial resection of the tendon showed reduced stiffness and increased elongation

Long-term outcomes of the four-corner fusion of the wrist: A systematic review

BACKGROUND: Four-corner fusion (4CF) is a motion sparing salvage procedure that is used to treat osteoarthritis secondary to advanced scapholunate collapse or longstanding scaphoid nonunion advanced collapse. Little is known about the long-term survivorship and outcomes of 4CF. AIM: To report on clinical and functional long-term outcomes as well as conversion rates to total wrist fusion or arthroplasty. METHODS: The systematic review protocol was registered in the international prospective register of systematic reviews (PROSPERO) and followed the PRISMA guidelines. Original articles were screened using four different databases. Studies with a minimum Level IV of evidence that reported on long-term outcome after 4CF with a minimum follow-up of 5 years were included. Quality assessment was performed using the Methodological Index for Non-Randomized Studies criteria. RESULTS: A total of 11 studies including 436 wrists with a mean follow-up of 11 ± 4 years (range: 6-18 years) was included. Quality assessment according to Methodological Index for Non-Randomized Studies criteria tool averaged 69% ± 11% (range: 50%-87%). Fusion rate could be extracted from 9/11 studies and averaged 91%. Patient-reported outcomes were extracted at last follow-up from 8 studies with an average visual analog scale of 1 ± 1 (range: 0-2) and across 9 studies with an average Disabilities of the Arm, Shoulder and Hand score of 21 ± 8 (range: 8-37). At last follow-up, the cumulative conversion rate to total wrist fusion averaged 6%. There were no conversions to total wrist arthroplasty. CONCLUSION: The 4CF of the wrist is a reliable surgical technique, capable of achieving a good long-term patient satisfaction and survivorship with low rates of conversion to total wrist fusion

Aspects of chemically modified nucleosides in RNA solid-phase synthesis and NMR spectroscopy

ursprüngliche Ansicht, dass eine RNA Sequenz einer einzigen, klar definierten Sekundärstruktur entspricht, wurde in den letzten Jahrzehnten weithin vom realistischeren Bild abgelöst, dass die biologische Funktion der RNA stark mit der Fähigkeit zusammenhängt ein ganzes Ensemble an unterschiedliche Strukturen einzunehmen. Obwohl es wohl-etablierte Techniken gibt, um statische Strukturen zu untersuchen, gibt es immer noch einen Mangel an praktikablen Methoden um strukturelle Veränderungen von RNA und vorübergehend, gering besetzte Zustände („angeregte Zustände“) oder dynamische Eigenschaften zu untersuchen. Um bessere Einblicke in biologische Prozesse zu bekommen, an denen RNA beteiligt ist, sind verbesserte Methoden um das dynamische Verhalten von RNA zu analysieren dringend notwendig. Die Verwendung von NMR aktiven RNA Sonden, ist ein weit verbreiteter Ansatz um strukturelle Veränderungen von RNA oder dynamische Flexibilität von Biomolekülen zu untersuchen. Einige Studien mit 19F NMR Sonden wurden in der Vergangenheit sehr erfolgreich in unserem Labor durchgeführt. Fluor kommt nicht natürlich in RNA Molekülen vor, bietet jedoch mehrere Vorteile für die Verwendung in der NMR Spektroskopie, wie die 100% natürliche Häufigkeit des NMR aktiven 19F Isotops (Spin ), große Anisotropie der chemischen Verschiebung und Dispersion und enge Signale, wegen der schnellen transversalen Relaxation. Ein einzelnes Fluoratom in einem großen Biomolekül, resultiert jedoch oft in Sensitivitätsproblemen wie schlechtem Verhältnis von Signal zu Rauschen und breiten Signalen. Um für dieses Problem einen Lösung anzubieten, wurde 2‘-deoxy-2‘-SCF3 Adenosin und 2‘-deoxy-2‘-SCF3 Guanosine synthetisiert, in Analogie zur Arbeit an 2‘-deoxy-2‘-SCF3 Uridin, publiziert von Fauster et al., 2012. Die SCF3-Gruppe stellt ein isolobales Spinsystem dar (keine Protonen Entkopplung notwendig), enthält drei chemisch äquivalente Fluoratome, was in einer Signalzunahme um den Faktor drei resultiert und einem einzigen scharfen Signal. Die erhaltenen Bausteine wurden in RNA eingebaut und ihre Fähigkeit RNA sekundär strukturellen Veränderungen zu untersuchen konnten gezeigt werden. Wenn die in RNA neue Funktionalität jedoch in einer doppelsträngigen Region positioniert wurde, führte das zu einer sehr ausgeprägten Destabilisierung des RNA Doppelstranges. Es wurde die Hypothese aufgestellt, die dann bestätigt werden konnte, dass das von der Verschiebung der Zucker Konformation von der in RNA natürlichen C2‘-endo zur C3‘-endo Konformation kommt, welche zu einer Störung der Wasserstoffbrückenbindung und des Basestackings führt. Da Nukleosidmodifikationen die ein thermodynamisches Design des RNA Doppelstranges erlauben besonders für RNA interferenz (RNAi) Anwendungen erwünscht sind, wurde die SCF3-Gruppe in RNAi Experimenten am BASP1 Gen in Hühner DF1 Zellen angewandt (in Kollaboration mit Markus Hartl und Klaus Bister vom Institut für Biochemie, CMBI, Universität Innsbruck). Zusätzlich soll erwähnt werden, dass für die Synthese von 2‘-deoxy-2‘-SCF3 Guanosine eine Schutzgruppenstrategie verwendet wurde, die auf der Arbeit von Simeone et al., 2011 basiert. Dadurch konnten typische Schwierigkeiten in der chemischen Synthese von Guanosinderivaten, wie schlechte Löslichkeit, hohe Polarität und lange mehrschrittige Prozeduren, die unweigerlich zu geringen Gesamtausbeuten führten vermieden werden. Das führte zur Idee, dieses Schutzgruppenkonzept für die Guaninbase direkt in der RNA Festphasensynthese zu verwenden. Dafür wurden 2‘-geschützte (TBDMS, TOM) O6-tbu, N2-boc2 oder N2-Hboc Guanosinphosphoramiditbausteine synthetisiert und in einer ‚proof of principal‘ Studie verwendet. Bereits die ersten Ergebnisse waren sehr vielversprechend und ermöglichten die Isolierung von RNA hoher Qualität und vollständig entschützt unter standard Entschützungs- und standard RNA Aufarbeitungsbedingungen. Zusätzlich konnten die Vorteile des Konzepts für den chemischen Syntheseweg, durch die Synthese von 2‘-deoxy-2‘-SCF3, O6-tbu, N2-boc2 Guanosinphosphoramidit, 2‘-O-[(3-phthalimidopropoxy)methyl], O6-tbu, N2-Hboc Guanosinphosphoramidit und von 2‘-deoxy-2‘-azido, O6-tbu, N2-boc2 Guanosinphosphordiester Bausteins gezeigt werden. Trotzdem soll erwähnt werden, dass bei RNA die mit dem neuen Boc-Schutzgruppenkonzept synthetisiert wurden eine geringe Menge (3-8%) an tert-butyl-RNA Addukt beobachtet wurde, welche jedoch gut vom Hauptprodukt durch HPLC Anionenaustausch Chromatographie trennbar war. Meiner Meinung nach, wird dieser kleine Nachteil mehr als wettgemacht durch die Vorteile für die chemische Synthese der Guanosinderivate. Basierend auf Fluorsonden, eine neuen 19F Carr-Purcell-Meiboom-Gill Relaxation Dispersions Methode wurde in Kollaboration mit Christoph Kreuz und Martin Tollinger entwickelt und untersucht, die eine neue Möglichkeit darstellt um RNA Dynamik zu bestimmen. Diese Methode erlaubt die präzise und genaue Messung von dynamischen Gleichgewichten und den Übergang zwischen unterschiedlichen Zuständen. Außerdem hilft es, Probleme die von klassischen CPMG Experimenten bekannt sind zu überwinden, wie Signalüberlappung, 13C13C skalare Kopplung und die besonders arbeitsintensive Probenpräparation in Kombination mit langen Messzeiten. Um einen Proton-entkoppelten 19F-NMR Sonde zu erhalten, wurde der 5-F,6-D Uridinphosphoramiditbaustein synthetisiert und an bestimmten Positionen in RNA eingebaut. Die Methode wurde an mehreren Beispielen in einer ‚proof of principal‘ Studie bestätigt und die klare Dateninterpretation, kurzen Messzeiten und hohe Genauigkeit wurde gezeigt.original view that one single RNA sequence corresponds to one single secondary structure was widely superseded in the past decades with the more realistic picture that the biological function of RNA is strongly connected with its ability to dynamically sample an entire ensemble of different structures. Although there are well established techniques to investigate static structures, there is still a lack of practicable methods to analyze RNA structural transitions, transiently, low populated states (so called excited states) or dynamic features. In order to get more profound insights into biological processes, in which RNA participates, improved methods to determine the dynamic behavior of RNA are urgently needed. The application of NMR sensitive RNA probes is a widely used approach for the investigation of RNA structural rearrangement or dynamic flexibility of biomolecules. Some studies using 19F NMR probes were very successfully executed in our laboratory in the past. Fluorine, which is naturally not occurring in RNA molecules, offers numerous advantages for its use in NMR spectroscopy, like 100% abundance of the NMR active 19F isotope (spin ), high chemical shift anisotropy and dispersion, narrow signals due to fast transversal relaxation. A single fluorine atom in a large biomolecule, often results in sensitivity problems, like bad signal to noise ratio and broad signals. In order to offer a solution to this problem, the 2'-deoxy-2'-SCF3 adenosine and 2'-deoxy-2'-SCF3 guanosine were synthesized, in analogy to work on uridine, published by Fauster et al., 2012. The SCF3 moiety constitutes an isolobal spin system (no proton decoupling necessary), containing three chemically equivalent fluorine atoms what results in a threefold intensity increase, and one single, sharp signal. The resulting building blocks were incorporated into RNA and their ability to investigate RNA secondary structure rearrangements could be demonstrated. However, if the novel moiety resided in a double stranded region, it led to profound destabilisation of the RNA duplex. It was hypothesized, and then affirmed, that this results from a shift of the sugar pucker from the in RNA naturally occurring C2-endo to the unusual C2-endo conformation, which led to disruption of hydrogen bonding and base stacking interactions. Since nucleoside modifications, which allow a defined thermodynamic design of an RNA duplex, are highly desired for RNA interference (RNAi) applications and therefore, the 2-SCF3 modification was tested in RNAi experiments on the BASP1 gene in chicken DF1 cells (in collaboration with Markus Hartl and Klaus Bister, Institute for Biochemistry, CMBI, University of Innsbruck). Additionally, it should be mentioned that in the 2'-deoxy-2'-SCF3 guanosine synthesis pathway a guanine nucleobase protection group pattern, based on work of Simeone et al., 2011, was applied. This allowed overcoming common difficulties of guanosine derivatives in chemical synthesis like bad solubility, high polarity, and long multistep procedures, which inevitably resulted in low overall yields. This led to the idea to apply this guanosine base protection concept directly in RNA solid-phase synthesis. Therefore 2-protected (TBDMS, TOM) O6-tbu, N2-boc2 or N2-H(boc) guanosine phosphoramidite building blocks were synthesized to be applied in a prove of principal study. Already the first results were found to be very promising, allowing the isolation of high quality, fully unprotected, crude RNA after standard RNA solid-phase synthesis and standard RNA processing. Additionally, the benefits of the concept in the chemical synthetic pathway were illustrated by the successful synthesis of 2 modified guanosine derivatives, namely the 2'-deoxy-2'-SCF3 O6-tbu, N2-boc2 guanosine phosphoramidite, the 2-O-[(3-phthalimidopropoxy)methyl], O6-tbu, N2-H(boc) guanosine phosphoramidite and the 2-deoxy-2-N3, O6-tbu, N2-boc2 guanosine phosphodiester building block. However, it should be mentioned, that the RNA synthesized with the novel boc-protected guanosine derivatives resulted in the formation of a minor amount (3-8%) of tert-butyl RNA adducts, which were well separable in HPLC anionic exchange chromatographic analysis. In my opinion this drawback is more than over-compensated by the benefits in the chemical synthesis of the guanosine derivatives. Based on fluorine probes, a novel 19F based Carr-Purcell-Meiboom-Gill relaxation dispersion (CPMG RD) method was developed in collaboration with Christoph Kreutz and Martin Tollinger and investigated, which offers another possibility to determine RNA dynamics. This method enables precise and accurate measurements of dynamic equilibria and the interconversion of different states. Additionally it helps to overcome the problems of signal overlap, 13C13C scalar coupling and the highly laborious sample preparations combined with long experimental times, known from classical CPMG experiments on RNA. In order to provide a proton decoupled 19F-NMR probe, the 5-F,6-D uridine phosphoramidite building block was synthesized, and incorporated into RNA at distinct positions. The method was confirmed in a prove of principal study and the straight-forward data interpretation, short experimental times and high accuracy was demonstrated on a few examples.eingereicht von Mag. rer. nat. Lukas JudZusammenfassung in deutscher SpracheKumulative Dissertation aus Acht ArtikelnUniversität Innsbruck, Dissertation, 2016OeBB(VLID)137595

Dual Sequential Short Anterior Correction in Double Major Adolescent Idiopathic Scoliosis

STUDY DESIGN retrospective comparative study. INTRODUCTION The standard surgical technique for double major adolescent idiopathic scoliosis (AIS) has been the fusion of both thoracic and thoracolumbar/lumbar curves from the posterior approach. Although short anterior correction is established in AIS with single thoracic or thoracolumbar/lumbar curves, anterior correction in double major curves has not yet been described. The purpose of this study is to compare this novel technique with standard posterior pedicle screw instrumentation in double major AIS. METHODS 19 consecutive patients with a double major AIS were treated surgically either with pedicle screw instrumentation and posterior fusion (n = 11) or dual anterior short instrumentation and fusion (n = 8) of both curves. The mean follow-up was 5.6 ± 3 years (2-10 years). Clinical and radiologic results, results of pulmonary function, and Scoliosis Research Society (SRS) questionnaire are analyzed and compared. RESULTS The length of fusion was 7.6 ± 0.7 vertebrae with the anterior technique and 12 ± 1 vertebrae with the posterior technique (p < .001). Cobb angle correction was 78% and 53% in thoracic curves, and 80% and 59% in lumbar curves with posterior and anterior technique respectively (p < .05). The preoperative pulmonary function remained unchanged to the last follow-up in both groups. The scores of SRS-24 questionnaire were similar preoperatively and at the last follow-up in both groups. CONCLUSION This novel technique of dual sequential short anterior correction is an alternative to the standard posterior long fusions in the double major AIS. A significantly less amount of mobile segments needs to be fused leaving the thoracolumbar junction mobile and saving at least one lumbar mobile segment distally. LEVEL OF EVIDENCE Level III

Correction of complex three-dimensional deformities at the proximal femur using indirect reduction with angle blade plate and patient-specific instruments: a technical note

BACKGROUND Corrective osteotomies for complex proximal femoral deformities can be challenging; wherefore, subsidies in preoperative planning and during surgical procedures are considered helpful. Three-dimensional (3D) planning and patient-specific instruments (PSI) are already established in different orthopedic procedures. This study gives an overview on this technique at the proximal femur and proposes a new indirect reduction technique using an angle blade plate. METHODS Using computed tomography (CT) data, 3D models are generated serving for the preoperative 3D planning. Different guides are used for registration of the planning to the intraoperative situation and to perform the desired osteotomies with the following reduction task. A new valuable tool to perform the correction is the use of a combined osteotomy and implant-positioning guide, with indirect deformity reduction over an angle blade plate. RESULTS An overview of the advantages of 3D planning and the use of PSI in complex corrective osteotomies at the proximal femur is provided. Furthermore, a new technique with indirect deformity reduction over an angle blade plate is introduced. CONCLUSION Using 3D planning and PSI for complex corrective osteotomies at the proximal femur can be a useful tool in understanding the individual deformity and performing the aimed deformity reduction. The indirect reduction over the implant is a simple and valuable tool in achieving the desired correction, and concurrently, surgical exposure can be limited to a subvastus approach

Mal-angulation of femoral rotational osteotomies causes more postoperative sagittal mechanical leg axis deviation in supracondylar than in subtrochanteric procedures

PURPOSE Alteration of the postoperative frontal mechanical leg axis is a known problem in femoral rotational osteotomies. However, the maintenance of the sagittal mechanical leg axis seems also important. Goal of this study was to investigate the impact of femoral rotational osteotomies on the sagittal mechanical leg axis and to identify the degree of mal-angulation of the osteotomy planes that alter the postoperative sagittal alignment relevantly. METHODS Using 3D bone models of two patients with a pathologic femoral torsion (42° antetorsion and 6° retrotorsion), subtrochanteric and supracondylar rotational osteotomies were simulated first with an osteotomy plane perpendicular to the mechanical femoral axis (baseline osteotomy plane), second with predefined mal-angulated osteotomy planes. Subsequently, five different degrees of rotation were applied and the postoperative deviations of the sagittal mechanical leg axes were analyzed. RESULTS Using the baseline osteotomy plane, the sagittal mechanical leg axis changed by 0.4° ± 0.5° over both models. Using the mal-angulated osteotomy planes, maximum deviation of the sagittal mechanical leg axis of 4.0° ± 1.2° and 11.0° ± 2.0° was observed for subtrochanteric and for supracondylar procedures, respectively. Relevant changes of more than 2° were already observed with mal-angulation of 10° in the frontal plane and 15° of rotation in supracondylar procedures. CONCLUSION Relevant changes of the postoperative sagittal mechanical leg axis could be observed with just slight mal-angulation of the osteotomy planes, in particular in supracondylar procedures and in cases with higher degrees of rotation. However, osteotomies perpendicular to the femoral mechanical axis showed no relevant alterations

A real 3D measurement technique for the tibial slope: differentiation between different articular surfaces and comparison to radiographic slope measurement

BACKGROUND The tibial slope plays an important role in knee surgery. However, standard radiographic measurement techniques have a low reproducibility and do not allow differentiation between medial and lateral articular surfaces. Despite availability of three-dimensional imaging, so far, no real 3D measurement technique was introduced and compared to radiographic measurement, which were the purposes of this study. METHODS Computed tomography scans of 54 knees in 51 patients (41 males and 10 females) with a mean age of 46 years (range 22-67 years) were included. A novel 3D measurement technique was applied by two readers to measure the tibial slope of medial and lateral tibial plateau and rim. A statistical analysis was conducted to determine the intraclass correlation coefficient (ICC) for the new technique and compare it to a standard radiographic measurement. RESULTS The mean 3D tibial slope for the medial plateau and rim was 7.4° and 7.6°, for the lateral plateau and rim 7.5° and 8.1°, respectively. The mean radiographic slope was 6.0°. Statistical analysis showed an ICC between both readers of 0.909, 0.987, 0.918, 0.893, for the 3D measurement of medial plateau, medial rim, lateral plateau and lateral rim, respectively, whereas the radiographic technique showed an ICC of 0.733. CONCLUSIONS The proposed novel measurement technique shows a high intraclass agreement and offers an applicable opportunity to assess the tibial slope three-dimensionally. Furthermore, the medial and lateral articular surfaces can be measured separately and one can differentiate the slope from the plateau and from the rim. As three-dimensional planning becomes successively more important, our measurement technique might deliver a useful supplement to the standard radiographic assessment in slope related knee surgery. LEVEL OF EVIDENCE Level III, diagnostic study

Applicability of augmented reality in orthopedic surgery - A systematic review

BACKGROUND: Computer-assisted solutions are changing surgical practice continuously. One of the most disruptive technologies among the computer-integrated surgical techniques is Augmented Reality (AR). While Augmented Reality is increasingly used in several medical specialties, its potential benefit in orthopedic surgery is not yet clear. The purpose of this article is to provide a systematic review of the current state of knowledge and the applicability of AR in orthopedic surgery. METHODS: A systematic review of the current literature was performed to find the state of knowledge and applicability of AR in Orthopedic surgery. A systematic search of the following three databases was performed: "PubMed", "Cochrane Library" and "Web of Science". The systematic review followed the Preferred Reporting Items on Systematic Reviews and Meta-analysis (PRISMA) guidelines and it has been published and registered in the international prospective register of systematic reviews (PROSPERO). RESULTS: 31 studies and reports are included and classified into the following categories: Instrument / Implant Placement, Osteotomies, Tumor Surgery, Trauma, and Surgical Training and Education. Quality assessment could be performed in 18 studies. Among the clinical studies, there were six case series with an average score of 90% and one case report, which scored 81% according to the Joanna Briggs Institute Critical Appraisal Checklist (JBI CAC). The 11 cadaveric studies scored 81% according to the QUACS scale (Quality Appraisal for Cadaveric Studies). CONCLUSION: This manuscript provides 1) a summary of the current state of knowledge and research of Augmented Reality in orthopedic surgery presented in the literature, and 2) a discussion by the authors presenting the key remarks required for seamless integration of Augmented Reality in the future surgical practice. TRIAL REGISTRATION: PROSPERO registration number: CRD42019128569

The impact of mal-angulated femoral rotational osteotomies on mechanical leg axis: a computer simulation model

BACKGROUND: Subtrochanteric or supracondylar femoral rotational osteotomies are established surgical treatments for femoral rotational deformities. Unintended change of the mechanical leg axis is an identified problem. Different attempts exist to plan a correct osteotomy plane, but implementation of the preoperative planning into the surgical situation can be challenging. Goal of this study was to identify the critical threshold of mal-angulation of the osteotomy plane and of femoral rotation that leads to a relevant deviation of the postoperative mechanical leg axis using a computer simulation approach. METHODS: Three-dimensional (3D) surface models of the lower extremity of two patients (Model 1: 42° femoral antetorsion; Model 2: 6° femoral retrotorsion) were generated from computed tomography data. First, baseline subtrochanteric and supracondylar rotational osteotomies, perpendicular to the femoral mechanical axis were simulated. Afterwards, mal-angulated osteotomies in sagittal and frontal plane followed by different degrees of rotation were simulated and frontal mechanical axis was analyzed. RESULTS: 400 mal-angulated osteotomies have been simulated. Mal-angulation of ±30° with 30° rotation showed maximum deviation from preoperative mechanical axis in subtrochanteric osteotomies (4.0° ± 0.4°) and in supracondylar osteotomies (12.4° ± 0.8°). Minimal mal-angulation of 15° in sagittal plane in subtrochanteric osteotomies and mal-angulation of 10° in sagittal plane in supracondylar osteotomies altered the mechanical axis by > 2°. Mal-angulation in sagittal plane showed higher deviations of the mechanical axis (up to 12.4° ± 0.8°), than in frontal plane mal-angulation (up to 4.0° ± 1.9°). CONCLUSION: A femoral rotational osteotomy, perpendicular to the femoral mechanical axis, has no considerable influence on the mechanical leg axis. However, mal-angulation of femoral rotational osteotomies showed relevant changes of the mechanical leg axis. In supracondylar respectively subtrochanteric procedures, mal-angulation of only 10° in combination with already 15° of femoral rotation respectively mal-angulation of 15° in combination with 30° of femoral rotation, can lead to a relevant postoperative mechanical leg axis deviation of more than 2°, wherefore these patients probably would benefit from the use of navigation aids

Meniscus sizing using three-dimensional models of the ipsilateral tibia plateau based on CT scans - an experimental study of a new sizing approach

PURPOSE Selection of a meniscus allograft with a similar three-dimensional (3D) size is essential for good clinical results in meniscus allograft surgery. Direct meniscus sizing by MRI scan is not possible in total meniscectomy and indirect sizing by conventional radiography is often inaccurate. The purpose of this study was to develop a new indirect sizing method, based on the 3D shape of the ipsilateral tibia plateau, which is independent of the meniscus condition. METHODS MRI and CT scans of fifty healthy knee joints were used to create 3D surface models of both menisci (MRI) and tibia plateau (CT). 3D bone models of the proximal 10 mm of the entire and half tibia plateau (with / without intercondylar area) were created in a standardized fashion. For each meniscus, the best fitting "allograft" couple out of all other 49 menisci were assessed by the surface distance of the 3D meniscus (best available allograft), of the 3D tibia plateau (3D-CT) and by the radiographic method of Pollard (2D-RX). RESULTS 3D-CT sizing was significantly better by using only the half tibia plateau without the intercondylar area (p < 0.001). But neither sizing by 3D-CT, nor by 2D-RX could select the best available allograft. Compared to 2D-RX, 3D-CT sizing was significantly better for the medial, but not for the lateral meniscus. CONCLUSIONS Automatized, indirect meniscus sizing using the 3D bone models of the tibia plateau is feasible and more precise than the previously described 2D-RX method.. However, further technical improvement is needed to select always the best available allograft