Adrian Skwara

Sagittal plane kinematics of fixed- and mobile-bearing total knee replacements

PurposeThe objective of this prospective, randomized, patient- and observer-blinded study was to analyze, in vivo, the knee joint kinematics in the sagittal plane in a patient population that had received either a fixed or a mobile TKA.MethodsThirty-one patients (57 knees) were evaluated by means of fluoroscopy during unloaded flexion and extension against gravity as well as during step up and step down with full weight bearing. In these 31 patients, 22 fixed-bearing TKAs, 16 mobile-bearing TKAs, and 19 natural knee joints were included. Fluoroscopic radiographs were evaluated by measuring the “patella tendon angle” in relation to the knee flexion angle, as a measure of anteroposterior translation, as well as the “kinematic index,” as a measure of reproducibility.ResultsDuring unloaded movement, fluoroscopic analysis did not show a significant difference between both types of prosthesis design and the natural knee. In the weight-bearing movement, both types of TKA designs revealed a more linear patellar tendon angle curve, with a greater angle in extension and in flexion than in the natural knees. In the mobile-bearing group, interindividual deviations from the mean during weight-bearing movements were significantly less than in the fixed-bearing group.ConclusionsNo functional advantage of mobile-bearing TKA over fixed-bearing devices could be found. Both TKA designs showed the typical kinematics of an anterior instability. These results only apply to cruciate retaining mobile-bearing TKA with a bearing that allows both rotation and anteroposterior translation, using a sagittal plane kinematics analysis evaluated by such methodology. A possible influence of less variability of the kinematic pattern on clinical results still needs to be confirmed.Level of evidenceProspective comparative study, Level II.

Changes of gait patterns and muscle activity after intraarticular treatment of patients with osteoarthritis of the knee: a prospective, randomised, doubleblind study.

Evaluation of gait performance and muscle activity patterns as well as clinical efficacy and safety after intraarticular injections with hyaluronan (Ostenil) compared with triamcinolone (Volon A10) injections in patients with knee osteoarthritis. This was a prospective, randomised, double-blind clinical trial evaluating the influence of five injections of hyaluronan or triamcinolone on gait pattern and muscle activity. For the clinical evaluation visual analogue scale, Lequesne index, and Knee Society Score were used. Quality of life was estimated with the SF-36. The definitive analysis was performed on the population who received all five injections and were examined in the two follow-up visits. Fifteen patients were treated with triamcinolone and 20 with hyaluronan. Significant improvement could be demonstrated for pain scale and clinical scores in both groups. Gait patterns showed significant differences only for Knee Abduction Moment (p=0.007) in the hyaluronan group and for Maximum Vertical Force 1 and 2 between the both groups in the follow up visit (p=0.018) (p=0.019). In both groups there was no significant difference regarding to muscle activity. Quality of life showed no changes in all visits between the groups. Hyaluronan was not superior to triamcinolone. The results suggest that treatment with hyaluronan can reduce pain and improve knee function. A significant short term improvement in gait and muscle activity patterns, however, was not observed, in either hyaluronan or triamcinolone.

Decrease in the expression of the type 1 PTH/PTHrP receptor (PTH1R) on chondrocytes in animals with osteoarthritis

BackgroundTo evaluate the expression of the type 1 PTH/PTHrP receptor (PTH1R) on chondrocytes from hyaline cartilage over the course of osteoarthritis (OA).MethodsIn 12 NZW rabbits, the anterior cruciate ligament (ACL) was resected to create anterior instability of the knee. In 12 control rabbits, only a sham operation, without resection of the ACL, was performed. Four animals from each group were killed at 3, 6, and 12 weeks. After opening the knee joint, OA was macroscopically graded and hyaline cartilage of the load-bearing area was evaluated histologically according to the Mankin scale and by immunostaining for PTH1R.ResultsThere was a positive linear correlation between the time after surgery and the macroscopic and histologic OA scores. The scores in the control group were constant over the time course. Immunostaining showed significantly less expression of PTH1R in the experimental compared to the control group after 6 (P < 0.05) and 12 weeks (P < 0.01). In the experimental group, a negative linear correlation between PTH1R expression and macroscopic and histologic grades was found.ConclusionsThe results show an in vivo decrease in the expression of PTH1R on chondrocytes over the time course of OA. Further studies are needed to evaluate whether new treatment approaches could evolve from this knowledge.

Influence of a training session on postural stability and foot loading patterns in soccer players

Sport specific movements coming along with characteristic plantar pressure distribution and a fatigue of muscles result in an increasing postural sway and therefore lead to a decrease in balance control. Although single soccer specific movements were expatiated with respect to these parameters, no information is available for a complete training session. The objective of the present observational study was to analyze the direct influence of soccer training on postural stability and gait patterns and whether or not these outcomes were altered by age. One hundred and eighteen experienced soccer players participated in the study and were divided into two groups. Group 1 contained 64 soccer players (age 13.31±0.66 years) and Group 2 contains 54 ones (age 16.74±0.73 years). Postural stability, static plantar pressure distribution and dynamic foot loading patterns were measured. Our results showed that the soccer training session, as well as the age, has relevant influence on postural stability, while the age only (excluding the training) has an influence on static plantar pressure distribution. The parameters of dynamic assessment seem therefore to be affected by age, training and a combination of both. Training and young age correlate with a decreased postural stability; they lead to a significant increase of peak pressure in the previously most loaded areas, and, after reaching a certain age and magnitude of absolute values, to a change in terminal stance and preswing phase of the roll-over. Moreover, younger players show an inhomogenous static plantar pressure distribution which might be the result of the decreased postural control in the young age.

Revision of tibial TKA components: bone loss is independent of cementing type and technique: an in vitro cadaver study

BackgroundDifferent bone cements and various cementation techniques can lead to different bone loss in revision surgery. We investigated the degree of tibial bone loss depending on different cements and techniques.Methods30 tibia specimens were matched into three groups (10 each). In all cases Genesis II tibia component were implanted. In two groups, the tibia base plate alone was cemented with Palacos® R+G and Refobacin® Bone Cement R. In the third group, both tibial base plate and tibial stem were cemented with Palacos® R+G. Afterwards, the specimens were axial loaded with 2000 N for 10,000 cycles. Tibial components were explanted and the required time to explantation was recorded. Bone loss after explantation was measured by CT.ResultsOn CT, there was no significant difference in bone loss between cementing techniques (p = 0.077; 95% CI -1.14 - 21.03) or the cements themselves (p = 0.345; 95% CI -6.05 - 16.70). The required time to explantation was 170.6 ± 54.89, 228.7 ± 84.5, and 145.7 ± 73.0 seconds in the first, second, and third groups, respectively.ConclusionsCement technique and type do not influence tibial bone loss in simulated revision surgery of the tibial component in knee arthroplasty.

Damages of the tibial post in constrained total knee prostheses in the early postoperative course – a scanning electron microscopic study of polyethylene inlays

BackgroundInvestigation of the risk of fracture of the polyethylene (PE) inlay in constrained total knee prostheses.MethodsThree unused and seven polyethylene inlays that had been implanted in a patients knee for an average of 25.4 months (min 1.1 months, max 50.2 months) were investigated using scanning electron microscopy (SEM). All inlays were of the same type and size (Genesis II constrained, Smith & Nephew). The PE surface at the transition from the plateau to the post was analyzed.ResultsThe unused inlays had fissure-free surfaces. All inlays that had been implanted in a patients knee already had distinct fissures at the front and backside of the post.ConclusionThe fissures of the transition from the plateau to the post indicated a loading-induced irreversible mechanical deformation and possibly cause the fracture of the inlay.

Initial stability of a new cementless fixation method of a tibial component with polyaxial locking screws: a biomechanical in vitro examination

IntroductionCementless fixation of the tibial component is critical as reduced initial stability leads to implant failure. In this experimental in vitro study, a new fixation method of the tibial component using polyaxial locking screws is evaluated using Roentgen stereophotogrammetric analysis (RSA).Materials and MethodsA special prototype of a tibial component with four polyaxial locking screws was tested on 10 fresh-frozen human tibia specimens. The components were tested with an axial load of 2000 N for 10,000 cycles. Radiographs in two views were performed before loading, after 1000 and after 10,000 cycles, respectively. Besides rotation and translation along the x-, y-, and z-axes, endpoints for RSA were maximum subsidence (MaxSub), maximum lift off (MaxLiftOff) and maximum total point motion (MTPM).ResultsMaxSub increased from −0.5 mm (SD = 0.2) after 1000 cycles to −0.9 mm (SD = 1.1). MaxLiftOff was 0.1 mm after 1000 cycles and did not increase after 10,000 cycles. The MTPM was 0.7 mm (SD = 0.3) after 1000 cycles and 1.1 mm (SD = 1.1) after 10,000 cycles. Two out of nine implants showed an MTPM ≥ 1.0 mm after 10,000 cycles.ConclusionsPolyaxial locking screws can potentially improve the initial stability of tibial components. The results of this study indicate that the use of such screws in total knee arthroplasty may be of interest in the future. Further experimental and clinical investigation is needed.

Der Einfluss der Patellakinematik auf die tibiale Rotation nach Knie-Totalendoprothesen-Implantation / Influence of patellar position on tibial rotation after total knee arthroplasty

Zusammenfassung Ziel: Die Implantation von Knietotalendoprothesen erfordert in der Mehrzahl die Resektion des vorderen Kreuzbandes. Aufgrund entstehender ligamentärer Insuffizienz ist die tibiale Rotation verstärkt von anderen Faktoren abhängig. Die vorliegende Studie diente zur dynamischen in vitro-Messung des Einflusses der durch die mediolaterale Patellaposition bestimmten Zugrichtung des Kniestreckapparates auf die tibiale Rotation nach Implantation von zwei unterschiedlichen Knieendoprothesen. Material und Methode: Patella- und Tibiakinematik wurden zunächst anhand von 10 physiologischen, „fresh-frozen” humanen Kniegelenkspräparaten in einem Kniegelenkskinemator, der einen isokinetischen Extensionsversuch simuliert, ermittelt. Anschließend erfolgte die Messung nach Implantation der Interax®- bzw. Genesis II®-Knieendoprothese in je fünf Präparaten und eine Bewertung von signifikanten Unterschieden der Kniegelenkskinematik. Ergebnisse: Die maximale mediale Position der physiologischen Patella betrug -6,6 mm (entspricht Lateralisierung) relativ zum Tibiazentrum, die maximale tibiale Außenrotation 4,1°. Nach Implantation der Genesis II®-Knieendoprothese verringerte sich die tibiale Außenrotation signifikant (p=0,03) bei relativer Medialisierung der Patella (p=0,01), wohingegen sich nach Implantation der Interax®-Knieendoprothese eine signifikant (p=0,01) erhöhte tibiale Außenrotation bei einer physiologisch entsprechenden Lateralisierung der Patella zeigte. Schlussfolgerung: Die Ergebnisse der Studie lassen einen wesentlichen Einfluss der mediolateralen Patellaposition auf die tibiale Rotation nach Implantation einer Knieendoprothese vermuten, wobei keines der getesteten Prothesensysteme in der Lage ist, eine physiologische Gelenkkinematik vollständig zu reproduzieren.

Role of Electrochemically Activated Solution in Asepsis in Osteoblasts and Chondrocytes in vitro

ABSTRACT Purpose: Implant infections are severe complications in orthopedic surgery. Treatment using antibiotics is often unsuccessful without removing the implant due to biofilm formation. In this context, antiseptics may be a potential option. These solutions have a wide antimicrobial spectrum but often cause damage to the local cell populations. In these cases, electrochemically activated solutions (ECAS) may be an alternative. Methods: Staphylococcus aureus was cultured overnight on polyethylene platelets under different growing conditions (standard-/-different biofilm inducing conditions). The samples were treated with an ECAS (0%–30%) and analyzed with regard to their antimicrobial efficacy and their effect on biofilm structures by determining the living bacterial count and scanning electron microscopy. Osteoblast and chondrocyte cell lines (MG-63, and CAL-78, respectively) were cultured to confluence and treated with an ECAS. Total cell count, metabolic activity using FDA staining, and proliferation using Ki67 staining were analyzed. Results: ECAS showed antimicrobial activity in concentrations <1%. In cases of biofilm formation, bacterial toxicity could be detected at concentrations from 3.75 –7.5%. At these same concentrations, a visible change in biofilm structure was observed. Regarding biocompatibility rates, up to 7.5% (of osteoblasts) and 3.75% (of chondrocytes) had little influence on metabolic activity and proliferation. Conclusion: ECAS provide good antimicrobial efficacy while maintaining high biocompatibility. These results suggest that these solutions may provide promising alternatives in the treatment of implant-associated infections.

Korrelation von elektromyographischen und klinischen Ergebnissen nach bikondylären Kniegelenksprothesen / Correlation of Electromyographic and Clinical Results Following Implantation of Bicondylar Knee Prostheses

Aim of the study: To investigate clinical findings in patients receiving bicondylar sledge prostheses, and their correlation with electromyographic measurements in comparison with healthy volunteers. Material and Methods:An average of 31.9 months after implantation of a bicondylar sledge prosthesis, 15 patients were clinically examined and compared with 11 control subjects. Electromyographic measurements of the rectus femoris, vastus medialis and lateralis, semitendinosus, biceps femoris, tibialis anterior, and gastrocnemius muscles were obtained. Results: All clinical scores were significantly poorer in the patient group. The activity of the vastus lateralis was significantly reduced. The activity in the lower leg of the operated side was significantly higher than in the control group. Significant differences were found in the tibialis anterior and gastrocnemius muscles between controls and patients. Analysis of the correlation between the clinical scores and the electromyographic measurements showed no significance. Conclusion: The clinical results correlated only slightly with the electromyographic activity of the muscles investigated. The commonly presumed quadriceps insufficiency was not confirmed.