Imprecise prediction of implant sizes with preoperative 2D digital templating in total knee arthroplasty

PURPOSE

To analyze the match between preoperatively determined implant size (2D templating) and intraoperatively used implant size in total knee arthroplasty (TKA). Also examined were the factors that might influence templating accuracy (gender, surgeon experience, obesity, etc.).

MATERIALS AND METHODS

The study was retrospective and conducted in a specialized ENDOCERT arthroplasty center. Digital templating was done with the MediCAD software. If the planned and implanted TKA components (both femur and tibia) were the same size, the match was classified "exact." A deviation of ± one size (at the femur or tibia or both) was classified "accurate." A deviation of ± two or more sizes (at the femur or tibia or both) was classified "inaccurate." Obesity, gender, implant type and surgeon experience were investigated for potential influence on templating accuracy. Chi-square tests and Cohen's weighted kappa test were used for statistical analysis.

RESULTS

A total of 482 cases [33.6% male, 66.4% female, age 69 ± 11, body mass index (BMI) 30.3 ± 5.8] were included. When the femur and tibia were taken together, exact size match was observed in 34% (95% CI 29.9-38.3%) of cases, accurate size match in 57.5% (95% CI 53-61.8%) and inaccurate size match in 8.5% (95% CI 6.3-11.2%). Inaccurate size match prolonged operative time (p = 0.028). Regarding the factors potentially influencing templating accuracy, only gender had a significant influence, with templating being more accurate in men (p = 0.004). BMI had no influence on accuracy (p = 0.87). No effect on accuracy was observed for implant type and surgeon experience.

CONCLUSIONS

The accuracy of 2D size templating in TKA is low, even in a specialized ENDOCERT arthroplasty center. The study findings challenge the usefulness of preoperative 2D size templating and highlight the importance of more reliable templating methods.

LEVEL OF EVIDENCE

Level III (retrospective observational study).

Material modifications enhancing the antibacterial properties of two biodegradable poly(3-hydroxybutyrate) implants

The aim of this study was to evaluate the antimicrobial efficacy of adding a gentamicin palmitate (GP) coating and zirconium dioxide (ZrO₂) to biodegradable poly(3-hydroxybutyrate) (PHB) to reduce biofilm formation. Cylindrical pins with and without a coating were incubated in Müller-Hinton broth inoculated with 2 × 10⁵ colony-forming units (CFU) ml-1 of Staphylococcus aureus for 2 d or 7 d, then sonicated to disrupt biofilms. Pure PHB (PHB + GP) and PHB pins with ZrO₂ added (PHBzr + GP) were coated with GP and compared with PHB pins lacking a coating (PHB). Cells (CFU) were counted to quantify the number of bacteria in the biofilm and a cell proliferation assay was employed to evaluate metabolic activity, and scanning electron microscopy (SEM) was performed to visualize the structure of the biofilm. After 2 d of incubation there were significantly more cells in biofilms on PHB pins than PHB + GP and PHBzr + GP pins (p < 0.0001), and cells in the sonication fluid obtained from GP-coated pins exhibited significantly lower metabolic activity than cells from uncoated PHB pins (p < 0.0001). After 7 d of incubation metabolic activity was lowest for PHBzr + GP, with significant differences between PHB and PHBzr + GP (p = 0.001). SEM revealed more cells attached to the surface, and more structured biofilms, on pins without a coating. Coating pins with GP significantly reduced early biofilm formation on PHB implants. This could lower the potential risk of surgical site infections when using PHB implants. Addition of ZrO₂ might further enhance the antibacterial properties. Such modification of the implant material should therefore be considered when developing new biodegradable PHB implants.

Bildgebende Diagnostik patellofemoraler Störungen

Hintergrund

Patellofemorale Störungen sind häufig. Zur diagnostischen Abklärung gehört neben einer spezifischen Anamnese und detaillierten körperlichen Untersuchung auch die bildgebende Diagnostik. Das Ziel dieses Artikels ist es, die verschiedenen bildgebenden Techniken darzustellen, die zur Diagnostik patellofemoraler Störungen angewandt werden.

Material und Methoden

Es erfolgte eine Suche der in der Literatur beschriebenen bildgebenden Techniken sowie der darin ersichtlichen Befunde bei patellofemoralen Störungen.

Ergebnisse

Die Bildgebung des Patellofemoralgelenks muss sowohl eine Beurteilung von Traumafolgen bzw. einer Degeneration des Gelenks als auch eine Analyse der für die patellofemorale Instabilität relevanten anatomischen Risikofaktoren ermöglichen. Die Basisdiagnostik hierfür stellt das Röntgen in 3 Ebenen dar. Eine Ganzbeinstandaufnahme ermöglicht die Detektion von Achsfehlstellungen. Der Goldstandard zur Bestimmung von Torsionsfehlern und dem TT-TG–Abstand (Distanz zwischen der Tuberositas tibiae und der Trochleagrube) ist die Computertomographie (CT). Die Magnetresonanztomographie (MRT) ermöglicht eine dreidimensionale Darstellung der Weichteilstrukturen wie dem medialen patellofemoralen Ligament (MPFL) sowie eine Beurteilung der Trochleamorphologie. Die SPECT-CT („single photon emission computed tomography“) zur Darstellung des Knochenstoffwechsels bleibt speziellen Fragestellungen vorbehalten.

Diskussion

Die bildgebende Diagnostik patellofemoraler Störungen ist multimodal. Entsprechend der Fragestellung reicht die Diagnostik von der alleinigen Basisdiagnostik bis hin zu innovativen Untersuchungstechniken wie der SPECT-CT.

[Operate, cancel, postpone or select?]

Gefäßchirurgische Zentren in Österreich (n = 15) wurden Mitte April 2020 mit erklärendem Begleitschreiben des Vorstands der Österreichischen Gesellschaft für Gefäßchirurgie (ÖGG) eingeladen, an einer Onlineumfrage über die Implikationen der COVID-19-Pandemie teilzunehmen. Insgesamt 12 Zentren (80 %) haben den Fragebogen ausgefüllt.

Alle Zentren waren mit positiv getesteten Patienten und 75 % auch mit positiv getesteten Mitarbeitern konfrontiert. Deutlich seltener war dies jedoch an den gefäßchirurgischen Abteilungen (positiv getestete Patienten in 25 %/Mitarbeiter in 33 %). Elektive Eingriffe wurden an allen Abteilungen entweder gestoppt (abgesagt oder verschoben) oder selektiv eingeschränkt. Dies betraf u. a. auch symptomfreie Patienten mit Karotisstenose, Aortenaneurysma kleiner 7 cm, peripherem Aneurysma, PAVK im Stadium II nach Fontaine oder Varikose. In allen Zentren wurden weiterhin uneingeschränkt gefäßchirurgische Notfälle behandelt. Uneinheitlich war das Vorgehen bei chronischen Ulzera, chronischer Mesenterialinsuffizienz, symptomfreiem Aortenaneurysma größer 7 cm und in der Shuntchirurgie.

Insgesamt war v. a. die zum Zeitpunkt der OP-Verschiebungen unklare Befristung der Maßnahmen problematisch, somit war auch das Risiko der abgesagten bzw. hinausgezögerten Behandlung nicht leicht abschätzbar. Für die Indikationen mit uneinheitlichem Vorgehen sollte unizentrisch und multizentrisch das Ergebnis der Patienten analysiert werden, auch hinsichtlich der mit der Verschiebung assoziierten psychologischen Belastung. Zudem bedürfen auch die aufgrund der COVID-19-Pandemie erfolgten Veränderungen im Alltag einer kritischen Auswertung, auch hinsichtlich demografischer und geografischer Unterschiede. Es ist anzunehmen, dass die Auswirkungen der COVID-19-Pandemie langfristig bedeutsam sind.

Results of universal ultrasound screening for developmental dysplasia of the hip: a prospective follow-up of 28 092 consecutive infants

AIMS

The purpose of this study was to analyze the incidence of the different ultrasound phenotypes of developmental dysplasia of the hip (DDH), and to determine their subsequent course.

PATIENTS AND METHODS

A consecutive series of 28 092 neonates was screened and classified according to the Graf method as part of a nationwide surveillance programme, and then followed prospectively. Abnormal hips were followed until they became normal (Graf type I). Type IIb hips and higher grades were treated by abduction in a Tübinger orthosis until normal. Dislocated hips underwent closed or open reduction.

RESULTS

Overall, 90.2% of hips were normal at birth. Type IIa hips (8.9%) became normal at a median of six weeks (interquartile range (IQR) 6 to 9). Type IIc and IId hips (0.67%) became normal after ten weeks (IQR 7 to 13). There were 19 type lll and eight type lV hips at baseline. There were 24 closed reductions and one open reduction. No late presentations of DDH were detected within the first five years of life.

CONCLUSION

The incidence of DDH was eight per 1000 live births. The treatment rate was 1% (n = 273). The rate of first operations on the newborn hip was 0.86, and rate of open surgery was 0.04. The cumulative rate of open surgery was 0.07. The authors take the view that early identification and treatment in abduction of all dysplastic hips in early childhood reduces the rate of open reduction and secondary DDH-related surgery later in life. Cite this article: Bone Joint J 2018;100-B:1399-1404.

[Operative therapy of isolated patellofemoral arthritis. Biomechanics as a guide]

BACKGROUND

The treatment of patellofemoral arthritis places high demands on orthopedists. The exact analysis of the underlying pathobiomechanical relationships is the basis for every therapy decision.

METHODS

Soft tissue procedures, such as medial patellofemoral ligament (MPFL) reconstruction for stabilization and bone interventions for alignment optimization (e.g. tuberosity transfer and corrective osteotomy) can play a role in treatment. In cases of advanced patellofemoral arthrosis these interventions can be used as well as in combination with partial joint replacement. For the choice of implant the use of anatomical prosthesis types is recommended because with these components the number of additional procedures can be reduced.

CONCLUSION

The success of patellofemoral prosthetics depends mainly on the recognition of biomechanical deviations. If these can be corrected the risk of implant failure can be reduced.

Injury of the right and left inferior epigastric artery during the implantation of a stand-alone ALIF cage through a left retroperitoneal approach: a case report

Various perioperative vascular complications of anterior lumbar spine procedures have been described in orthopaedic literature. We report the unusual case of a perioperative bleeding from the right and left epigastric inferior artery occurring when using a stand-alone ALIF device (Synfix, Synthes, Oberdorf, Switzerland) at the L5/S1 level through an anterior left retroperitoneal approach. The primary stability of the Synfix is achieved by four divergent screws which are inserted through the anteriorly located plate into the neighbouring vertebral endplates. For the screw insertion the surrounding structures have to be mobilized more extensively than during a “standard” anterior lumbar interbody fusion (ALIF) procedure. The epigastric inferior arteries were embolized by applying polyvinyl alcohol particles and metal coils. The retroperitoneal haematoma caused herniation of the external rectus sheath. Hence revision surgery with removal of the haematoma and resuturing of the rectus sheath were performed. Insertion of divergent screws of the Synfix device may cause severe distension and rupture of the epigastric vessels. This case shows that a lesion of the right epigastric artery may be a hazard even in left retroperitoneal approaches. To the author’s knowledge this is the first case describing a lesion of the right epigastric artery during an ALIF procedure through a left retroperitoneal approach.

[Detection of inferior products in arthroplasty and implementation of findings: a retrospective analysis of the Boneloc incident]

AIM

By a retrospective assessment of the Boneloc incident, a bone cement which had an inferior outcome in terms of survival rate, the value of published datasets for the detection of inferior outcomes was evaluated.

METHOD

A structured literature review of English and German peer reviewed journals was conducted. The articles were assessed with respect to revision rate and statements about the product. In a standardised methodology, adjusted for number of cases and follow-up period, the revision rate was calculated. Main goal was to assess the agreement of published information from different datasets.

RESULTS

In the first 4 years after Boneloc had been brought on the market exclusively experimental studies were published, most of which were in favour of the product. In 1995, clinical studies, migration analyses and register-based articles were published. Most of them reported about inferior results, in the same year Boneloc was taken from the market worldwide. Sample-based clinical follow-up studies were not able to contribute to the decision-making process, they were published with a delay of several years and were underpowered from a statistical point of view. All of them published critical statements--after the product had no longer been available on the market for many years. The average revision rate in sample-based studies exceeded the reference value in the Norwegian Arthroplasty Register 7.35-fold. When the inferior results with Boneloc were published, the product had already disappeared from the national markets in Scandinavian countries' operating registers. The central position of orthopaedic scientific societies in the entire outcome monitoring system in these countries seems to be a key factor for success and rapid reaction to identified problems.

CONCLUSION

Arthroplasty registers and migration analyses have the highest value for the rapid and reliable detection of inferior outcomes in comparative analyses of published articles. Experimental studies did not agree with the performance of the product in a retrospective view, the data cannot be transferred from the estimation of future clinical outcome like survival rates. The involvement of scientific societies in the assessment and dissemination of the results is a key factor to realise potential benefit by an advanced quality monitoring project like arthroplasty registers.