Overstretching Expectations May Endanger the Success of the “Millennium Surgery”

Total hip arthroplasty (THA) is an extremely successful treatment strategy. Patient expectations, however, have increased; if not properly guided by surgeons, at present, patients expect next to pain-free restoration of the joint and a fast return to work and sports. While the revision rates after THA also increased in younger patients, knowledge on musculoskeletal loads still remains sparse, and the current recommendations on postoperative rehabilitation are based on expert opinions only. The aim of this study was to unravel biomechanical contact conditions in "working age" (60 years, 67.7 +/- 8.6 years) patients during activities recommended post-THA. We hypothesized that working age patients would show substantially increased hip contact loads compared to older patients. The in vivo joint contact force (F-res) and torsion torque (M-tors), reflecting the main contact load situation, experienced during activities of daily living and sports activities were measured in a unique group of 16 patients with instrumented THA. We summarized patient activities and sports recommendations after THA mentioned within the literature using PubMed (without claim of completeness). The measurements showed that younger working age patients experienced significant (p = 0.050) increased M-tors (21.52 +/- 9.11 Nm) than older retirement age patients (13.99 +/- 7.89 Nm) by walking. Bowling, as a recommended low-impact sport, was associated with F-res of up to 5436 N and M-tors of up to 108 Nm in the working age group, which were higher than the F-res (5276 N) and M-tors (71 Nm) during high-impact soccer. Based on our results, age was proven to be a discriminator in joint loading, with working age patients presenting with increased loads compared to retirement age patients, already during daily activities. The current patient recommendations have led to further increased joint loadings. If THA cannot be delayed in a patient, we propose counselling patients on a carefully considered return to sports, focusing on low-impact activities, as indicated hereby. The findings from this work illustrate the need to provide critical feedback to patient expectations when returning to work and sports activities. Patients returning to more intensive sports activities should be carefully monitored and advised to avoid as much overloading as possible

Laminar air flow reduces particle load in TKA—even outside the LAF panel: a prospective, randomized cohort study

Purpose: Released particles are a major risk of airborne contamination during surgery. The present prospective study investigated the quantitative and qualitative particle load in the operating room (OR) depending on location, time of surgery and use of laminar air flow (LAF) system. Methods: The particle load/m(3) was measured during the implantation of 12 total knee arthroplasties (6 x LAF, 6 x Non-LAF) by using the Met One HHPC 6 + device (Beckmann Coulter GmbH, Germany). Measurement was based on the absorption and scattering of (laser) light by particles and was performed at three different time-points [empty OR, setting up, ongoing operation) at 3 fixed measurement points [OR table (central LAF area), anaesthesia tower (marginal LAF area), surgical image amplifier (outside LAF area)]. Results: Independent of time and location, all measurements showed a significantly higher particle load in the Non-LAF group (p < 0.01). With ongoing surgical procedure both groups showed increasing particle load. While there was a major increase of fine particles (size < 1 mu m) with advancing activity in the LAF group, the Non-LAF group showed higher particle gain with increasing particle size. The lowest particle load in the LAF group was measured at the operating column, increasing with greater distance from the operating table. The Non-LAF group presented a significantly higher particle load than the LAF group at all locations. Conclusion: The use of a LAF system significantly reduces the particle load and therefore potential bacterial contamination regardless of the time or place of measurement and therefore seems to be a useful tool for infection prevention. As LAF leads to a significant decrease of respirable particles, it appears to be a protective factor for the health of the surgical team regardless of its use in infection prevention. Level of evidence: I

Correction of severe valgus osteoarthritis by total knee arthroplasty is associated with increased postoperative ankle symptoms

Purpose: The aim of this study was to assess the mid-term clinical outcome of the ankle joint after total knee arthroplasty (TKA) in high-grade valgus osteoarthritis. Methods: In this case–control study, n=36 patients with a preoperative mechanical tibiofemoral angle (mTFA)≥15° who underwent TKA between December 2002 and December 2012 were included. The control group (mTFA<15°) of n=60 patients was created using case matching. Radiological [mechanical tibiofemoral angle (mTFA) and ankle joint orientation to the ground (G-AJLO)] and clinical parameters [Foot Function Index (FFI), Knee Society Score, Forgotten Joint Score, and Range of Motion (ROM)] were analysed. The mean follow-up time was 59 months (IQR [56, 62]). Results: The degree of correcting the mTFA by TKA signifcantly correlated with the postoperative FFI (R=0.95, p<0.05), although the knee and ankle joint lines were corrected to neutral orientations. A cut-of value of 16.5° [AUC 0.912 (0.85–0.975 95% CI), sensitivity=0.8, specifcity=0.895] was calculated, above which the odds ratio (OR) for developing ankle symptoms increased vastly [OR 34.0 (9.10–127.02 95% CI)]. ROM restrictions of the subtalar joint displayed a strong sig nifcant correlation with the FFI (R=0.74, p<0.05), demonstrating that decreased ROM of the subtalar joint was associated with aggravated outcomes of the ankle joint. Conclusions: In this study, higher degrees of leg axis correction in TKA were associated with increased postoperative ankle symptoms. When TKA is performed in excessive valgus knee osteoarthritis, surgeons should be aware that this might trigger the onset or progression of ankle symptoms, particularly in cases of a stif subtalar joint. Level of evidence III

The Recovery of Weight-Bearing Symmetry After Total Hip Arthroplasty Is Activity-Dependent

This study aimed to characterize ipsilateral loading and return to weight-bearing symmetry (WBS) in patients undergoing total hip arthroplasty (THA) during activities of daily living (ADLs) using instrumented insoles. A prospective study in 25 THA patients was performed, which included controlled pre- and postoperative follow-ups in a single rehabilitation center of an orthopedic department. Ipsilateral loading and WBS of ADLs were measured with insoles in THA patients and in a healthy control group of 25 participants. Measurements in the THA group were performed at 4 different visits: a week pre-THA, within a week post-THA, 3-6 weeks post-THA, and 6-12 weeks post-THA, whereas the healthy control group was measured once. ADLs included standing comfortably, standing evenly, walking, and sit-to-stand-to-sit (StS) transitions. All ADLs were analyzed using discrete methods, and walking included a time-scale analysis to provide temporal insights in the ipsilateral loading and WBS waveforms. THA patients only improved beyond their pre-surgery levels while standing comfortably (ipsilateral loading and WBS, p < 0.05) and during StS transitions (WBS, p < 0.05). Nevertheless, patients improved upon their ipsilateral loading and WBS deficits observed within a week post-surgery across all investigated ADLs. Ipsilateral loading and WBS of THA patients were comparable to healthy participants at 6-12 weeks post-THA, except for ipsilateral loading during walking (p < 0.05) at the initial and terminal double-leg support period of the stance phase. Taken together, insole measurements allow for the quantification of ipsilateral loading and WBS deficits during ADLs, identifying differences between pre- and postoperative periods, and differentiating THA patients from healthy participants. However, post-THA measurements that lack pre-surgery assessments may not be sensitive to identifying patient-specific improvements in ipsilateral loading and WBS. Moreover, StS transitions and earlier follow-up time points should be considered an important clinical metric of biomechanical recovery after THA

CNS targets of adipokines

This is the author accepted manuscript. The final version is available from American Physiological Society via the DOI in this record.Our understanding of adipose tissue as an endocrine organ has been transformed over the last twenty years. During this time a number of adipocyte-derived factors or adipokines have been identified. This paper will review evidence for how adipokines acting via the central nervous system (CNS) regulate normal physiology and disease pathology. The reported CNS-mediated effects of adipokines are varied and include the regulation of energy homeostasis, autonomic nervous system activity, the reproductive axis, neurodevelopment, cardiovascular function, and cognition. Due to the wealth of information available and the diversity of their known functions, the archetypal adipokines leptin and adiponectin will be the focused on extensively. Other adipokines with established CNS actions will also be discussed. Due to the difficulties associated with studying CNS function on a molecular level in humans, the majority of our knowledge, and as such the studies described in this paper, comes from work in experimental animal models; however, where possible the relevant data from human studies are also highlighted

A new surgical technique for a better outcome after total kneearthroplasty

Die Implantation einer Kniegelenktotalendoprothese ist eine erfolgreiche und kosteneffiziente Methode zur Behandlung der Arthrose des Kniegelenks. Die Implantatüberlebensraten haben sich stetig verbessert. Jedoch sind nach wie vor nicht alle Patienten mit dem Ergebnis des Eingriffs zufrieden. Die Gründe dafür sind vielschichtig und werden sowohl von patientenabhängigen als auch patientenunabhängigen Faktoren beeinflusst. Die sozioökonomischen Auswirkungen der hohen Prävalenz von Restbeschwerden sind erheblich. Es besteht darum die dringende Notwendigkeit, das Outcome zu optimieren. Der kausale Zusammenhang zwischen Outcome und der mechanischen Funktionalität der Knieendoprothese ist unbestritten. Sowohl die Ausrichtung der Prothesenkomponenten, wie auch die Bandspannung bestimmen die Kinematik des Kniegelenks und damit die Funktion. Diese Determinanten wurden von uns in diversen Studien untersucht. Bei der Verwendung von konventionellen Instrumenten ist die Positionierung der Prothesenkomponenten im Raum ein bekanntes Problem. Patientenspezifische Instrumente können hier zu einer verbesserten Präzision führen. In unseren Untersuchungen fanden wir in allen untersuchten Ebenen eine verbesserte und reproduzierbare Implantationsgenauigkeit mit patientenspezifischen Instrumenten gegenüber der konventionellen Technik. Dabei schneiden die auf der Basis der MRTTechnologie gefertigten Blöcke in der koronaren postoperativen Beinachse besser ab. In der zweiten Arbeit zeigten wir, dass sich die Navigation nicht für eine zuverlässige Vorhersage der Komponentenposition eignet. Bei der Verwendung von Schnittblöcken ist es also nicht sinnvoll, aufgrund einer navigierten Kontrolle auf die exakte Implantatposition zu schließen. Bisher kamen patientenspezifische Instrumente ausschließlich bei Landmarken orientierten Operationstechniken zur Anwendung. Die Literatur zeigt, wie zu erwarten war, dass die alleinige Anwendung der patientenspezifischen Instrumente keine besseren klinischen Ergebnisse hervorbringt. Die von uns entwickelte Operationstechnik wurde in einer randomisierten Studie mit 25 Patienten überprüft. Unsere Untersuchungen zeigen sehr gute frühe klinische Ergebnisse. In der Studiengruppe waren keine Weichteilreleases notwendig. Nach unserem Wissen ist dies die erste Studie, die die potenziellen Vorteile der patientenspezifischen Instrumente mit der Gap-Balancing-Technik verbindet. Mit der Kombination aus patientenspezifischen Instrumenten und Gap-Balancing umgeht man die möglichen Nachteile der reinen Measured-Resection-Technik. Wir konnten zeigen, dass die kinematische Implantatausrichtung am Femur mit patientenspezifischen Instrumenten möglich ist. Dies kann den Anwendungsbereich der patientenspezifischen Instrumente in Zukunft erweitern, denn die neuen Ansätze wie True Measured Resection und Gap- Balancing setzen eine noch höhere Präzision und Flexibilität bei der Instrumentierung voraus. Die heute auf dem Markt befindlichen patientenspezifischen Instrumente, Computernavigationssysteme und Operationsroboter sind geeignet, das erforderliche Maß an Präzision zu erreichen. Patientenspezifische Instrumente können als Teil einer Prozessoptimierung die intraoperativen Abläufe verbessern, die Fehlerquoten verringern, sowie eine Individualisierung der Kniegelenktotalendoprothetik ermöglichen. Die Individualisierung wird sich sowohl auf das Design, als auch auf die Ausrichtung der Implantate auswirken. Implantatkomponenten müssen künftig in der Lage sein die individuelle, natürliche Kinematik des Kniegelenkes wiederherzustellen. Eine starre, landmarkenbasierte Ausrichtung wird zunehmend einer individuellen, kinematischen weichen. Dazu sind epidemiologische Studien notwendig, um Erkenntnisse über die präarthrotische Morphologie des Kniegelenks zu gewinnen. Außerdem gilt es zu klären, welche Tibiaposition zum Beispiel beim Varus-Morphotyp anzustreben ist, und welche Grenzen zu beachten sind. Dynamische und funktionelle Untersuchungen sind notwendig um die komplexe Kinematik des Kniegelenkes zu verstehen. Die Neuen, elektronischen Sensoren in den Probeinlays liefern erste interessante Daten zur Druckverteilung im ersetzten Kniegelenk. Die von uns durchgeführten Untersuchungen sind erste Schritte auf dem Weg zur individuellen und selektiven Kniegelenkendoprothetik.The individual anatomical reconstruction has been practised successfully in total hip arthroplasty for many years, the ideal implant position in TKA remains unknown. The main result of this work is that the newly developed surgical technique made it possible to combine measured resection PSI with a kinematic implant alignment for the first time. Adjustment of the bone resections in line with ligament tension was performed on the femur only, as higher failure rates are described for varus malpositioning of the tibia. If results are reliable, the soft tissue can be gradually released additionally to the adjusted femoral cut using the technique of Whiteside et al.. Changing to a neutral mechanical alignment at this time should be avoided, as the re- adjustment of the femoral cut will result in an elevation of the joint line and the need for more excessive medial soft tissue releases. Safe implementation of this surgical technique therefore seems to be possible without the risk of major outliers in the coronal plane. Regarding femoral rotation, this technique used a ligament-balanced approach like that in the conventional gap-technique. As the flexion gap symmetry and not the TEA is the reference for femoral rotation, it can deviate from the TEA. The three-month clinical follow-up showed a significant improvement in mobility and function compared with the preoperative findings. Consistent with these results, several studies have shown that a moderate residual postoperative varus in varus osteoarthritis leads to equally good and in some cases to superior outcomes. Whether this residual varus is associated with a shorter implant survival remains a subject of controversy. Comparative studies with a longer follow-up will follow. The present technique may not be feasible in cases of more severe deformity, extra-articular deformities or ligament instability. This surgical technique requires the use of special instruments and so for the time being it can only be performed in conjunction with the specific implant used. In conclusion, for the first time, the new surgical technique described here permits a functional, ligament-balanced implant alignment based on PSI. It was shown to be safe, with encouraging clinical and radiological results. Therefore, the advantages of the two surgical approaches can be used synergistically

Physiological joint line total knee arthroplasty designs are especially sensitive to rotational placement - A finite element analysis.

Mechanical and kinematical aligning techniques are the usual positioning methods during total knee arthroplasty. However, alteration of the physiological joint line and unbalanced medio-lateral load distribution are considered disadvantages in the mechanical and kinematical techniques, respectively. The aim of this study was to analyse the influence of the joint line on the strain and stress distributions in an implanted knee and their sensitivity to rotational mal-alignment. Finite element calculations were conducted to analyse the stresses in the PE-Inlay and the mechanical strains at the bone side of the tibia component-tibia bone interface during normal positioning of the components and internal and external mal-rotation of the tibial component. Two designs were included, a horizontal and a physiological implant. The loading conditions are based on internal knee joint loads during walking. A medialization of the stresses on the PE-Inlay was observed in the physiological implant in a normal position, accompanied by higher stresses in the mal-rotated positions. Within the tibia component-tibia bone interface, similar strain distributions were observed in both implant geometries in the normal position. However, a medialization of the strains was observed in the physiological implant in both mal-rotated conditions with greater bone volume affected by higher strains. Although evident changes due to mal-rotation were observed, the stresses do not suggest a local plastic deformation of the PE-Inlay. The strains values within most of the tibia component-tibia bone interface were in the physiological strain zone and no significant bone changes would be expected. The physiological cut on the articular aspect showed no detrimental effect compared to the horizontal implant

Bacterial Colonization of Irrigation Fluid during Aseptic Revision Knee Arthroplasty

Surgical risk factors for periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) are the subjects of ongoing research. It is unclear if there are specific locations of the surgical area that might act as a pathogen source. Due to the fact that bacterial replication occurs preferably under humid conditions, it was our aim to investigate if irrigation fluid reservoirs on the surgical covers are subject to bacterial colonization. We prospectively observed 40 patients with scheduled aseptic 1-stage TKA revision. At time intervals of 30 min, irrigation samples were tested for microbiological colonization. Additionally, the suction tip was investigated at the end of surgery. Overall, a bacterial detection rate of 25% was found (57/232 samples). Analysis for any positive microbial detection revealed pathogen findings of irrigation fluid in 41.7% of samples after 30 min with a constant increase up to 77.8% after 90 min. Twenty-three percent of suction tips showed bacterial colonization. Coagulase-negative staphylococci, accounting for the majority of PJI, were the predominant pathogens. After an average follow-up of 17 months, no PJI was confirmed. Despite the substantial bacterial load of irrigation fluid, PJI rates were not elevated. Nevertheless, we recommend that irrigation fluid reservoirs should be prevented and not withdrawn by suction