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Purpose The purpose of this study was to quantify the influence of medial open wedge high tibial osteotomy on patellar kinematics using optical computer navigation, as anterior knee pain infrequently occurs postoperatively and the reason is still being unknown. Methods Ten medial open wedge high tibial osteotomies at supratuberosity level in 5 full body specimens were performed. The effect of the surgical procedure on patellar kinematics, measured at 5 and 10 degrees of leg alignment correction angle, was analyzed and compared to native patellar kinematics during passive motion—regarding patella shift, tilt, epicondylar distance and rotation. Linear mixed models were used for statistical analysis, a two‐sided p value of ≤ 0.05 was considered statistically significant. Results Tilt behavior, medial shift and epicondylar distance did not show a significant difference regarding natural patellar kinematics at both osteotomy levels. Both osteotomy correction angles showed a significant less external rotation of the patella (p Conclusions Except less external rotation of the patella, medial open wedge high tibial osteotomy does not seem to relevantly alter patellar alignment during passive motion. Future clinical studies have to prove the effect of MOWHTO on patellar kinematics measured in this experimental setup, especially regarding its influence on anterior knee pain.

Weight-bearing long-leg radiographs are commonly used in orthopaedic surgery. Measured parameters, however, change when radiographs are conducted in different rotational positions of the leg. It was hypothesized that rotational errors are regularly present in long-leg radiographs resulting in wrong measurements. In 100 consecutive long-leg radiographs conducted according to the method of Paley, rotation was assessed by fibular overlap. Angular parameters in radiographs (mechanical lateral proximal femoral angle (mLPFA), mechanical lateral distal femoral angle (mLDFA), angle between the anatomical and mechanical femoral axis (AMA), mechanical medial proximal tibia angle (mMPTA), mechanical lateral distal tibial angle (mLDTA), and the mechanical femoral and tibial axis (mFA–mTA) were measured and deviations related to malrotation calculated. An average internal rotation of 8 degrees was found in lower limbs showing a range between 29 degrees of internal and 22 degrees of external rotation. As a result, mean differences before and after rotational correction for measured parameters (mLPFA, mLDFA, AMA, mMPTA, mLDTA, mFA–mTA) ranged between 0.4 and 1.7 degrees (−2.1; 5.6 95% confidence interval [CI]). In conclusion, malrotation of lower limbs is regularly present in long-leg radiographs. As all measured parameters are influenced by malrotation, correct lower limb rotation needs to be verified.

Trochlear dysplasia is one of the most important pathomorphologies predisposing to patellofemoral instability. The development of the trochlea groove is not well understood so far. We hypothesized that the underlying pathology of trochlear dysplasia is a medial hypoplasia. 110 magnetic resonance imaging (MRI) scans from adult knees, 55 with and 55 without trochlear dysplasia were analyzed. On the axial and sagittal T2 MRI sequences, the height (h), width (w) and depth (d) of the medial (MC) and lateral femoral condyle (LC) as well as the depth of the trochlea groove (dTG) were measured using a three-dimensional measuring algorithm. For all calculated values of the lateral femoral condyle, the comparison of both groups showed no significant difference (p = 0.95, p = 0.11, p = 0.07). The depth of the trochlear groove (dTG) showed significant lower values in the study group (p

The influence of different implantation techniques in TKA on tibiofemoral kinematics was analysed in few investigations so far. However, the influence on patellar kinematics remain unclear. The aim of the present investigation was to compare patellar kinematics of the natural knee with those of knees after both kinematically and mechanically aligned TKAs. Patellar kinematics of ten cadaveric knees before and after TKAs implanted using both a kinematic and mechanic alignment technique were investigated and compared using a commercial optical computer navigation system. There was a statistically significant difference between natural patellar kinematics and both implantation techniques analysing mediolateral shift. Patellar lateral tilt showed significant better results in the kinematically compared to the mechanically aligned TKAs. In terms of patella rotation, the patella of both mechanically and kinematically aligned TKAs showed significant higher values for external rotation compared to the natural knee. Regarding epicondylar distance again a significant better restoration of natural kinematics could be found in the kinematically aligned TKAs. Kinematically aligned TKAs showed a better overall restoration of patellar kinematics compared to a conventional mechanical alignment technique. In terms of clinical usefulness, the present study highlights the potential benefit for clinical outcome using a kinematically aligned implantation technique in TKA to achieve a better restoration of natural patellofemoral kinematics.

Background Patellar instability has a high incidence and occurs particularly in young and female patients. If the patella dislocates for the first time, treatment is usually conservative. However, this cautious approach carries the risk of recurrence and of secondary pathologies such as osteochondral fractures. Moreover, there is also risk of continuous symptoms apparent, as recurrent patella dislocation is related to patellofemoral osteoarthritis as well. An initial surgical treatment could possibly avoid these consequences of recurrent patella dislocation. Methods A prospective, randomized-controlled trial design is applied. Patients with unilateral first-time patella dislocation will be considered for participation. Study participants will be randomized to either conservative treatment or to a tailored patella stabilizing treatment. In the conservative group, patients will use a knee brace and will be prescribed outpatient physical therapy. The surgical treatment will be performed in a tailored manner, addressing the pathologic anatomy that predisposes to patella dislocation. The Banff Patellofemoral Instability-Instrument 2.0, recurrence rate, apprehension test, joint degeneration, and the Patella Instability Severity Score will serve as outcome parameters. The main analysis will focus on the difference in change of the scores between the two groups within a 2-year follow-up. Statistical analysis will use linear mixed models. Power analysis was done for the comparison of the two study arms at 2-year follow-up with regard to the BPII Score. A sample size of N = 64 per study arm (128 overall) provides 80% power (alpha = 0.05, two-tailed) to detect a difference of 0.5 standard deviations in a t-test for independent samples. Discussion Although several studies have already dealt with this issue, there is still no consensus on the ideal treatment concept for primary patellar dislocation. Moreover, most of these studies show a unified surgical group, which means that all patients were treated with the same surgical procedure. This is regarded as a major limitation as surgical treatment of patella dislocation should depend on the patient’s anatomic pathologies leading to patellar instability. To our knowledge, this is the first study investigating whether patients with primary patella dislocation are better treated conservatively or operatively with tailored surgery to stabilize the patella. Trial registration The study will be prospectively registered in the publicly accessible database www.ClinicalTrials.gov.

The purpose of this study was to quantify the influence of medial open wedge high tibial osteotomy on patellar kinematics using optical computer navigation, as anterior knee pain infrequently occurs postoperatively and the reason is still being unknown.Ten medial open wedge high tibial osteotomies at supratuberosity level in 5 full body specimens were performed. The effect of the surgical procedure on patellar kinematics, measured at 5 and 10 degrees of leg alignment correction angle, was analyzed and compared to native patellar kinematics during passive motion-regarding patella shift, tilt, epicondylar distance and rotation. Linear mixed models were used for statistical analysis, a two-sided p value of ≤ 0.05 was considered statistically significant.Tilt behavior, medial shift and epicondylar distance did not show a significant difference regarding natural patellar kinematics at both osteotomy levels. Both osteotomy correction angles showed a significant less external rotation of the patella (p 0.001, respectively) compared to natural kinematics.Except less external rotation of the patella, medial open wedge high tibial osteotomy does not seem to relevantly alter patellar alignment during passive motion. Future clinical studies have to prove the effect of MOWHTO on patellar kinematics measured in this experimental setup, especially regarding its influence on anterior knee pain.

Background:The operative therapy of patellofemoral arthritis requires an individual approach depending on the underlying injury. However, the literature lacks recommendations for its course of action.Purpose:To generate an expert recommendation of therapy for different patellofemoral abnormalities in patients suffering from isolated patellofemoral arthritis.Study Design:Consensus statement.Methods:To generate recommendations, the AGA Patellofemoral Committee performed a consensus process using the Delphi method based on the available literature on isolated patellofemoral arthritis.Results:In most statements and recommendations, a high percentage of consensus could be found. However, also in the expert group of the AGA Patellofemoral Committee, some controversies on the treatment of patellofemoral arthritis exist.Conclusion:The operative therapy of isolated patellofemoral arthritis is a challenging topic that leads to controversial discussions, even in an expert group. With this consensus statement of the AGA Patellofemoral Committee, recommendations on different operative treatment options were able to be generated, which should be considered in clinical practice.

Anterior knee pain after total knee arthroplasty (TKA) remains a widely discussed postoperative complication. In contrast to sports traumatology, the role of the dissected medial patellofemoral ligament (MPFL) using a medial parapatellar approach in TKA has not been discussed so far. In the present study, it was hypothesized that the attempted repair of the MPFL in TKA by simple closure of the joint capsule may not be successful in some cases, causing anterior knee pain. Furthermore, it was hypothesized, that the success of repair might be influenced by femoral component rotation. Forty patients received their TKA in a ligament-balanced and forty patients in a conventional measured-resection technique. After implantation of the TKA using a medial parapatellar approach, two titan clips were attached on both sides of the capsule incision. 3 days and 3 months after surgery, the dehiscence of the two clips was measured on skyline patella radiographs; additionally patellar tilt, shift, the Knee Society Score and the Feller Score were obtained. 48 patients showed an increase of capsule dehiscence. Patients with a capsule dehiscence of more than 4 mm showed significantly less improvement in the Feller score 3 months postoperatively than patients with a capsule dehiscence ≤4 mm. Regarding the radiological measurements and the clinical outcome, no significant difference between the ligament-balanced and the measured-resection group was found. The present results suggest that the successful repair of the MPFL after using a medial parapatellar approach in TKA could reduce the high rate of postoperative anterior knee pain. Furthermore, the appearance of capsule dehiscence and anterior knee pain does not seem to be dependent on the used operative technique.

Rotation of the lower limb in weight bearing long leg radiographs has a great impact on measured component and lower limb alignment parameters. We asked which rotational errors of long leg radiographs are present in a high volume centre and which radiological and clinical consequences arise regarding measured coronal component and lower limb alignment after total knee arthroplasty. In 100 long leg radiographs coronal femoral and tibial component alignment and hip knee ankle angle (HKA) were measured. Present rotational errors in long leg radiographs were determined by fibular overlap and its impact on alignment parameters calculated. A mean internal rotation of 8.1° (9.3 SD) with a range between 36° of internal and 16° of external rotation was found in long leg radiographs. This resulted in mean differences between measurements before and after rotational correction regarding femoral and tibial component alignment and HKA of 0.6–0.8° (range 3.5° valgus and 1.6° varus error). Clinically, 11 out of 100 patients were wrongly assigned to either mal- or well-alignment (neutral mechanical alignment within ±3° varus or valgus). Surgeons should be aware of potential rotational errors in long leg radiographs after total knee arthroplasty resulting in wrong measurements. In case of rotational errors, radiographs should be repeated or rotational corrections calculated. For study purposes only radiographs after rotational correction should be accepted.

Special characteristics must be taken into consideration for replacement arthroplasty in the elderly. The indications, preoperative preparation, postoperative care, implant selection, intraoperative technique, as well as clinical results reveal sometimes substantial differences compared to younger patients. Based on these findings it is important to individualize the approach to patient therapy, especially due to distinct differences between chronological and biological age in the elderly, in association with the level of activity and expectations on the new joint. All types of implants, each with implant-specific characteristics that must be taken into consideration, are available independent of the age of the patient. In summary, attributes such as stability and pain-free mobility have to be given priority in the elderly.

Introduction. Patellar instability (PI) is a common finding in children. Current parameters describing patellofemoral joint alignment do not account for knee size. Additionally, most parameters utilize joint-crossing tibiofemoral landmarks and are prone to errors. The aim of the present study was to develop a knee size-independent parameter that is suitable for pediatric or small knees and determines the malpositioning of the distal patellar tendon insertion solely utilizing tibial landmarks. Methods. Sixty-one pediatric knees were included in the study. The tibial tubercle posterior cruciate ligament distance (TTPCL) was measured via magnetic resonance imaging (MRI). The tibial head diameter (THD) was utilized as a parameter for knee size. An index was calculated for the TTPCL and THD (TTPCL/THD). One-hundred adult knees were analyzed to correlate the data with a normalized cohort. Results. The THD was significantly lower in healthy females than in males (69.3 mm ± 0.8 mm vs. 79.1 mm ± 0.7 mm; p<0.001) and therefore was chosen to serve as a knee size parameter. However, no gender differences were found for the TTPCL/THD index in the healthy adult study cohort. The TTPCL/THD was significantly higher in adult PI patients than in the control group (0.301 ± 0.007 vs. 0.270 ± 0.007; p=0.005). This finding was repeated in the PI group when the pediatric cohort was analyzed (0.316 ± 0.008 vs. 0.288 ± 0.010; p=0.033). Conclusion. The TTPCL/THD index represents a novel knee size-independent measure describing malpositioning of the distal patellar tendon insertion determined solely by tibial landmarks.

Correct rotational implant alignment is associated with increased postoperative function and implant survival in total knee arthroplasty (TKA). Due to conformity between tibial and femoral implants, particularly in full extension, we assumed a mutual interference of femoral and tibial component rotations. We, therefore, hypothesized that different rotational alignments of the tibial or femoral components change the rotational postures between the tibia and femur after TKA. In 10 healthy knees of whole body cadavers, TKA was performed. Both femoral and tibial components were implanted in different internal (6 degrees) and external (3 and 6 degrees) rotational alignments. Consequential osseous rotational changes between the tibia and the femur were measured in full extension using a commercial computer navigation device. External rotation of the femoral component resulted in significant external rotation of the tibia, while external rotation of the tibial component caused a significant internal rotation of the tibia. The opposite applied to femoral and tibial component internal rotations. Therefore, largest changes of the osseous tibiofemoral rotational postures were found by the combination of 6 degrees femoral component internal and 6 degrees tibial component external rotations (mean 11.2 degrees, standard deviation 5.0, p < 0.001), as both cause tibial internal rotation. In conclusion, the present results suggest that axial component alignment significantly affects lower limb rotational alignment. However, its clinical impact on forefoot progression, Q-angle, the patella, collateral, and cruciate ligaments, and surrounding soft tissues has to be clarified in further clinical and biomechanical studies.

Die Dyskinesie der Patella stellt ein relevantes Problem nach primarer Knietotalendoprothetik dar. Die Patellanavigation ermoglicht die Darstellung der Patellakinematik intraoperativ in Echtzeit bei dynamischer Untersuchung. In dem Videobeitrag wird die Technik der Patellanavigation bei der Knietotalendoprothetik demonstriert und eine mogliche Konsequenz der Messung dargestellt. Im berichteten Fall zeigt sich nach Implantation ein vermehrter lateraler Tilt nach Implantation der Knietotalendoprothese. Durch eine laterale Retinakulumerweiterungsplastik kann der vermehrte Tilt reduziert werden. In ausgewahlten Fallen ist die Patellanavigation geeignet, die Kinematik der Patella intraoperativ vor und nach Prothesenimplantation zu messen. Intraoperativ konnen dann noch Modifikationen der Implantatpositionierung oder erganzende Weichteileingriffe eine patellofemorale Dyskinesie verhindern.

Patellar maltracking due to incorrect component alignment is considered as a main reason for anterior knee pain after total knee arthroplasty (TKA). In contrast to coronal and axial component placement, the influence of sagittal component alignment on patellar kinematics has not been investigated so far. In ten lower cadaveric limbs, TKAs were implanted using a commercial computer navigation system. In six knees, the femoral component was aligned in 5° and in four knees in 0° of flexion, respectively. Patellar kinematics were registered by means of a computer navigation system using an additional patella tracking array and correlated with femoral and tibial sagittal component alignment. Sagittal component alignment significantly altered patellar mediolateral shift (p

The influence of cruciate-ligament-retaining (CR-TKA) and cruciate-ligament-substituting (CS-TKA) TKA on tibiofemoral kinematics was analysed in many investigations. However, the influence on patellar kinematics is unclear so far. The aim of this study was to compare patellar kinematics of the natural knee with those after CR- and CS-TKA. Patellar kinematics of nine healthy whole-body cadaveric knees before and after CR- and CS-TKA was investigated using a commercial optical computer navigation system. Patellar kinematics of the healthy knee was compared with those after CR- and CS-TKA. No significant difference between the natural knee and the knee after TKA or between both types of TKA for patellar kinematics could be found. Interestingly, both types of TKA resulted in a more medial patellar shift and a contrary patellar tilt and rotation behaviour. CR- and CS-TKA resulted in smaller values for patellar epicondylar distance at all flexion angles. Our study found no influence of prosthesis type on patellar kinematics. Factors like component alignment and prosthesis design seem to be more important in terms of adequate restoration of patellar kinematics in TKA than whether choosing CR- or CS-TKA.

BackgroundTotal hip arthroplasty (THA) could be associated with a higher failure rate in patients after osteonecrosis of the femoral head (ONFH) compared to a patient population with primary osteoarthritis prior THA, especially regarding the acetabular component. One major reason could be the compromised acetabular bone quality. Therefore, we performed a retrospective case matched study to assess: 1) Is there a difference in periprosthetic bone mineral density between patients with an ONFH prior THA and controls? 2) Do patients with an ONFH prior THA have a lower bone mineral density compared to controls? 3) Which region in the periprosthetic bone stock is more likely to present differences in periprosthetic bone mineral density between both groups?HypothesisWe hypothesized that there is a poorer bone mineral density (BMD) in the periacetabular bone stock in patients with an ONFH prior THA compared to controls receiving a THA due to primary osteoarthritis.Patients and methodsWe compared the BMD of 50patients with ONFH to 50controls with primary osteoarthritis prior THA using the same implant in mean 5years after surgery by means of dual energy X-ray absorptiometry (DXA). We analysed 3acetabular ROIs according to DeLee and Charnley in a modified measurement technique.ResultsIn ROI 3, representing acetabulum's upper aspect, statistically significant lower BMD values for the ONFH group could be found (P

Kinematically aligned total knee arthroplasty is associated with superior pain relief, increased flexion and a more normal feeling knee. It was hypothesized that due to restoring the knee’s natural anatomy, kinematically aligned knees show more physiological tibiofemoral kinematics than mechanically aligned knees. Investigations were performed in nine healthy cadaveric knees of whole bodies fixed by the Thiel method. Tibiofemoral kinematics of healthy knees and after kinematically and mechanically aligned total knee arthroplasty were assessed between 0° and 90° of flexion by a navigational device. Regarding tibial internal rotation or femoral roll back, respectively, kinematically aligned total knee arthroplasties showed no significant differences between 0° and 70° of flexion in comparison to knees before total knee arthroplasty. In contrast, mechanically aligned total knee arthroplasties showed significant changes between 10° and 90° of flexion. Kinematically aligned knees showed a significant changed abduction/adduction between 20° and 70° of flexion, mechanically aligned knees within 20° and 90° of flexion. In the present study setting kinematically aligned total knee arthroplasties showed more natural and physiological tibiofemoral kinematic pattern with regard to tibial internal rotation or femoral rollback, respectively, and tibial adduction than mechanically aligned total knee arthroplasties. While these results may support promising early clinical results of kinematical alignment proposing a better function, long-term results especially implant survival need to be awaited.

Purpose Several navigation-based kinematic studies of the knee have been published recently, but little information is available about reproducibility and reliability of the acquired data. The aim of the present study first is to determine reproducibility and reliability of kinematical measurements of healthy knees and knees after TKA (total knee arthroplasty) with regards to rotational and translational measurement parameters. Second the mathematical background, applicability, and limitations of investigating navigation-based kinematics should be compiled. Methods Using cadavers fixed by the Thiel method, in ten knees reproducibility of obtained angular and translational kinematic parameters were investigated before and after total knee arthroplasty. For this reason agreement of obtained data of a first and a second movement cycle and the same after a surgical intervention was assessed using a commercially available navigational device. Results For both angular and translational parameters in healthy knees and knees after total knee arthroplasty mean differences between measured parameters of the first and second movement cycle and after surgical intervention of less than 0.5° or millimeters (standard deviation 1.3 or less) or a inter class correlation of 0.92 and more, respectively, was found. Discussion Use of a commercial navigation system allows highly accurate investigations of knee kinematics in cadavers before and after TKA. This technique, which does not require any specific technical knowledge of the investigator, is in accordance with current accepted biomechanical methods.

Intramedullary rods are widely used to align the distal femoral cut in total knee arthroplasty. We hypothesised that both coronal (varus/valgus) and sagittal (extension/flexion) cutting plane are affected by rotational changes of intramedullary femoral alignment guides. Distal femoral cuts using intramedullary alignment rods were simulated by means of a computer-aided engineering software in 4°, 6°, 8°, 10°, and 12° of valgus in relation to the femoral anatomical axis and 4° extension, neutral, as well as 4°, 8°, and 12° of flexion in relation to the femoral mechanical axis. This reflects the different angles between anatomical and mechanical axis in coronal and sagittal planes. To assess the influence of rotation of the alignment guide on the effective distal femoral cutting plane, all combinations were simulated with the rod gradually aligned from 40° of external to 40° of internal rotation. Rotational changes of the distal femoral alignment guides affect both the coronal and sagittal cutting planes. When alignment rods are intruded neutrally with regards to sagittal alignment, external rotation causes flexion, while internal rotation causes extension of the sagittal cutting plane. Simultaneously the coronal effect (valgus) decreases resulting in an increased varus of the cutting plane. However, when alignment rods are intruded in extension or flexion partly contradictory effects are observed. Generally the effect increases with the degree of valgus preset, rotation and flexion. As incorrect rotation of intramedullary alignment guides for distal femoral cuts causes significant cutting errors, exact rotational alignment is crucial. Coronal cutting errors in the distal femoral plane might result in overall leg malalignment, asymmetric extension gaps and subsequent sagittal cutting errors.

Background The number of cases of orthopedic surgery is still increasing and postoperative pain management is of great importance for the patients. Therefore, in this study factors influencing the pain and the developement of pain in general in the first 7 days after total knee arthroplasty were examined. Material and methods A total of 28 patients were included in this prospectively designed trial and underwent total knee arthroplasty with psoas compartment and sciatic nerve regional anesthesia and additionally propofol sedation. Postoperative pain scores were documented using a numerical rating scale (NRS) and anthropometric data and perioperative parameters were correlated with the postoperative pain score. Results Evaluation of the pain values per interval showed that the maximum and the mean postoperative pain levels decreased up to day 4 after surgery and then increased. No significant effects of the analyzed parameters age, body mass index (BMI), duration of surgery and catheter indwelling time could be found. Female patients had significantly more pain than males in this collective. Conclusion The results show that there were no factors which have a significant influence on the degree of postoperative pain. Female patients suffered from more pain than males. There was an increase in pain after postoperative day 4 which might be the effect of more extensive mobilization and reduced effects of regional anesthesia. It is important that pain is treated in the early postoperative period.

Postoperative Wundinfektionen gehoren zu den haufigsten nosokomialen Infektionen. Aufgrund der hohen Inzidenz postoperativer Wundinfektionen kommen Strategien zur Vermeidung nosokomialer Infektionen hochste Bedeutung zu. Evidenzbasierte Masnahmen, wie die korrekte Gabe einer perioperativen Antibiose, Handehygiene, die Vermeidung einer praoperativen scharfen Rasur oder die Sanierung einer Kolonisation mit Staphylococcus aureus sind in nationalen und internationalen Empfehlungen gelistet. Doch nach wie vor existieren zahlreiche wissenschaftlich nicht bestatigte Masnahmen im Rahmen der perioperativen Infektionsprophylaxe, wie die Fortfuhrung einer perioperativen Antibiotikagabe uber mehrere Tage oder die Verwendung von OP-Helmen. Diese Masnahmen sind nicht wissenschaftlich belegt und sollten daher nicht zur Anwendung kommen. Nur die konsequente Anwendung von evidenzbasierten Masnahmen ist nachweislich infektionspraventiv.

Im Bereich der Hufte geschilderte Beschwerden sind oft nur schwer einzuordnen. Dies hat zum einen damit zu tun, dass Schmerzprojektion und Uberlappungen vorliegen konnen. Daher muss die gesamte Lenden-Becken-Huft-Region als eine Einheit verstanden werden, bei der es bei Veranderungen zu Ausstrahlungen im gesamten Bereich kommen kann. Zum anderen ist die Huftregion als solche von einer Vielfalt von anatomischen Strukturen gepragt. So konnen verschiedene Muskelanteile in ihrer Funktion beeintrachtigt sein und Lagebeziehungen der knochernen Strukturen oder auch Veranderungen der ubrigen Weichteile wie Ligamente, Sehneneinstrahlungen und Labrum Pathologien aufweisen. Differenzialdiagnostisch mussen auch die Leiste als Schwachstelle des Peritoneums und der Gefasverlauf berucksichtigt werden. Daher sind auch eine ausfuhrliche und zielgerichtete Anamnese, eine detaillierte funktionelle Prufung und vor allem spezifische Untersuchungen und Tests erforderlich, um die vorliegende Pathologie genauer einzugrenzen und uber gezielte, zum Teil weitergehende diagnostische Masnahmen eine definitive Abklarung zu erreichen. Der Orthopade muss wissen, welche Auffalligkeit zu welchen Problemen fuhren kann und welche anatomischen Strukturen Irritationen ausgesetzt sind. Die durch die klinische Untersuchung gewonnenen Ergebnisse sind die Grundlage fur eine gezielte bildgebende Diagnostik und folgerichtige Therapie.

Despite different surgical patellar interventions, the decision how to treat the patella during TKA remains controversial. The purpose of this study was to quantify the effect of different reconstructive patellar interventions on patellar kinematics during TKA using optical computer navigation. We implanted ten navigated TKAs in full body specimens. During passive motion, the effect of different surgical patellar interventions on patellar kinematics was analysed. A contrarily tilt behaviour was observed in the TKA group without patellar intervention compared to the natural knee. Lateral release led to similar tilt values ( P P

The number of total hip and knee arthroplasties (THA and TKA) is steadily increasing. Many factors that influence pain have been reported, but little is known about the correlation between the time of day and the duration of surgery and postoperative pain. On one hand, surgical interventions are performed faster due to economic pressure; on the other hand, obtaining sound surgical skills and a thorough education are most important for young surgeons, particularly at university hospitals. Amidst these different interests, it is the patient who should be the focus of all medical efforts. Therefore, our study investigated the effects of the time of day and the duration of total knee and hip arthroplasty on postoperative pain perception and patient satisfaction. 623 patients were analyzed 24 h after primary total knee or hip arthroplasty regarding pain, patient satisfaction, and side effects by means of the questionnaires of the German-wide project Quality Improvement in Postoperative Pain Management (QUIPS). The time of day and the duration of knee or hip arthroplasty were not correlated with maximum, minimum, and activity-related pain and patient satisfaction rated on a numeric rating scale (NRS). This study is the first to show that neither the time of day nor the duration of surgery has any influence on patient satisfaction and postoperative pain 24 h after total knee or hip arthroplasty; regarding these aspects, young orthopaedic surgeons may be trained in the operating theatre without time pressure.

Few data exist of kinematics of knees with varus and valgus deformities combined with osteoarthritis. The purpose of this study was to reveal different (1) tibiofemoral kinematics, (2) medial and lateral gaps, and (3) condylar liftoff of osteoarthritic knees with either varus or valgus deformity before and after total knee arthroplasty (TKA). For this purpose, 40 patients for TKA were included in this study, 23 knees with varus deformity and 17 knees with valgus deformity. All patients underwent computer navigation, and kinematics was assessed before making any cuts or releases and after implantation. Osteoarthritic knees with valgus deformity showed a significant difference in tibia rotation relative to the femur with flexion before and after TKA, whereas knees with varus deformity did not. Knees with a valgus deformity showed femoral external rotation in extension and femoral internal rotation in flexion, whereas knees with a varus deformity revealed femoral internal rotation in extension and femoral external rotation in flexion. In both groups, gaps increased after TKA. Condylar liftoff was not observed in the varus deformity group after TKA. In the valgus deformity group, condylar liftoff was detected after TKA at knee flexion of 50 degrees and more. This study revealed significant differences in tibiofemoral kinematics between osteoarthritic knees with a varus or valgus deformity before and after TKA. Valgus deformities showed a paradoxic movement pattern. These in vivo intraoperative results need to be confirmed using fluoroscopic or radiographic three-dimensional matching before and after TKA.

Aims and Objectives: In recent years, a steadily increasing number of total knee arthroplasty implants have been reported. After having ameliorated operation techniques and material, pain management and anesthetic methods have come into focus. Various anesthesia procedures for the surgical procedure itself as well as pain management programs have been developed. One of the main goals is to reduce postoperative pain and enable better and faster mobilization in the postoperative period. The present study aims to compare the use of general and regional anesthesia and their combination in terms of perioperative pain management and patient satisfaction. Materials and Methods: In the present cohort study, 15.326 patients were examined in 46 orthopedic departments after knee replacement surgery from 2009-2015. The parameters were analyzed on the first postoperative day as part of the project “QUIPS - Quality Improvement in Postoperative Pain Management”, an initiative to compare the outcome parameters in participating hospitals. Primary outcome values were pain levels (activity, minimum and maximum pain, and pain management satisfaction) on a NRS scale. Pain medication necessity was analyzed using the WHO pain ladder classification. Parameters were compared between the types of anesthesia used: general, regional and combination anesthesia. Results: Pain scores and pain management satisfaction were significantly better in the groups of either spinal or peripheral anesthesia combined with general anesthesia (p0.001, respectively). Patients who received the combination of general and spinal anesthesia were associated with the lowest need for opioids (p0.001). Conclusion: The use of a combined general and spinal anesthesia as well as using a combination of general and peripheral anesthesia in knee arthroplasty was associated with a highly significant advantage to other anesthetic techniques regarding perioperative pain management in daily clinical practice, but maybe below clinical relevance. Furthermore they were associated with positive tendency considering side effects and subjective well-being parameters.

Background Patellofemoral instability may lead to osteoarthritis, anterior knee pain, and patellar luxation. The purpose of this study was to conduct an exploratory investigation into the difference of patellar kinematics of healthy knees during extension/flexion cycles in neutral, varus and valgus alignment. Methods The three-dimensional patellar kinematics of 10 lower extremities of whole body cadavers were examined during passive motion, in neutral position, and under valgus and varus stress. Kinematics was recorded by means of an optical computer navigation system. Results The study samples did not significantly differ with regard to mediolateral patellar shift and epicondylar distance. Varus stress led to significantly higher external rotation than valgus stress ( P = 0.04) and to a significantly higher lateral patellar tilt than neutral position ( P = 0.016) and valgus stress ( P = 0.016). No difference was found between valgus stress and neutral position. Conclusion Analysis of tibiofemoral alignment alone is insufficient for predicting patellar kinematics.

Background In comparison to coronal, sagittal, and rotational alignment, translational alignment parameters have been widely neglected in total knee arthroplasty (TKA) so far. As there is a certain variable range of possible component placement in mediolateral, ventrodorsal, and proximodistal direction, we hypothesized that relative positions between the femoral and tibial bones are changed after TKA, resulting in a subluxation of knees. Methods In 10 knees of Thiel-embalmed whole body cadavers, the relative position between the femur and the tibia during passive flexion was measured before and after TKA by means of a navigational device. Results After TKA, in extension, femoral bones in average shifted 5.3 mm (standard deviation [SD] = 4.0, P = .002) laterally and 2.4 mm (SD = 3.1, P = .038) proximally in extension which, however, decreased throughout flexion. Furthermore, the ventrodorsal femoral position was altered, resulting in a slight relative dorsal shift (2.6 mm, SD = 4.5, P = .099) in extension, which continuously changed into a ventral shift (2.6 mm, SD = 4.3, P = .087) during flexion. Conclusion The present investigation reveals changed translational parameters between the tibia and the femur after TKA. The resulting subluxation of the knee may be responsible for changed kinematic patterns. These changes in tibofemoral position should be considered in future biomechanical studies. Main reasons for this effect might be a noncentral placement of tibial and femoral implants in relation to the proximal tibial and distal femoral anatomy, obscured intraoperative articular geometry, symmetric implants, and operative techniques. Smaller steps between different component sizes, asymmetric tibial implant design, or individual (anatomic) implants could help to minimize subluxation in TKA.

Background During flexion, normal knee kinematics consists of a complex combination of rolling, gliding, and rotation between femur and tibia. Although in vivo studies have shown wide interindividual variability, we hypothesized that knee kinematics is either correlated to the anatomy of the individual knee joint or to the anatomic alignment of the entire lower extremity. Methods The passive kinematics of 10 healthy knees was assessed in whole cadavers using a commercial computed tomography–free navigation device with intracortical pins. Rotational limb alignment or local anatomic parameters obtained by computed tomography scan or within a navigational procedure were correlated to tibial internal rotation and tibiofemoral abduction during flexion. Results Mean tibial adduction in full extension was 3.3° (range −2.2° to 7.8°). Tibial abduction and internal rotation showed significant interindividual variability, measuring 3.9° (range −0.8° to 9.7°) and 4.9° (range −3.5° to 14.8°) during flexion. An increase in both the mechanical tibiofemoral axis and the mechanical lateral distal femoral angle correlated with increased tibial internal rotation, whereas a decrease in the mechanical medial proximal tibial angle and an increase in the mechanical tibiofemoral axis were associated with increased tibial adduction. Conclusion The main finding of the present study is that knee kinematics is influenced by both intra-articular and extra-articular parameters. These results may be of interest in component alignment in total knee arthroplasty, correction of deformities, and malalignment after fracture healing of the lower extremity. Possible relationships should be investigated in future studies.

In total knee arthroplasty (TKA), intramedullary guides are often used for aligning the distal femoral cutting block. Because of the highly varying angles between the mechanical axis and the anatomical femoral axis (AMA), different valgus pre-sets have been recommended. The present study investigated the optimal valgus pre-set (measuring the AMA in long-leg radiographs or at 5°, 6°, 7° or 8° valgus) to align the cutting block perpendicularly to the mechanical axis. The AMA was preoperatively measured in weight-bearing long-leg radiographs. After alignment of the cutting block by means of an intramedullary rod, deviation of the block from the mechanical femoral axis was measured with a pinless navigation device. The true AMA (tAMA) was calculated by adding the valgus pre-set of the alignment rod to the deviation measured with the navigation device. Mean deviations between the tAMA and (a) the AMA measured by the surgeon, (b) the AMA calculated with the computer software, (c) 5°, (d) 6°, (e) 7° and (f) 8° valgus pre-sets were measured for each patient. The lowest mean differences were determined. The 40 knees measured showed a mean tAMA of 7.2° valgus (1.7 SD) (range 4°–11.5°). The following mean differences and 95 % limits of agreement were calculated: 2.2 (−1.2, 5.5) to the tAMA for the 5° valgus pre-set, 1.2 (−2.2, 4.5) for 6°, 0.2 (−3.2, 3.5) for 7° and −0.8 (−4.2, 2.5) for 8°. AMA measurements by the surgeon and with the digital medical planning software yielded mean differences of 0.6 (−3.1, 4.3) and 0.4 (−4.1, 4.8), respectively. In the present setting, the best mean distal femoral cutting block alignment perpendicular to the mechanical femoral axis could be achieved with a valgus pre-set of 7° and not by measuring the AMA. Nevertheless, we recommend conducting weight-bearing radiographs of the entire leg prior to TKA for easy detection of any anatomical varieties, old fractures, long stems of total hip arthroplasties or cement. However, surgeons must be aware that exact coronal component alignment can only be achieved by navigational devices. Diagnostic study, Level II.

Trabecular properties in osteonecrosis of the femoral head (ONFH) are altered for bone volume and structure in the femoral head and proximal femoral canal. We analysed the periprosthetic bone mineral density (BMD) as a correlate to bony ingrowth in patients with ONFH who received a cementless THA. We performed a matched-pair analysis of 100 patients with ONFH (n = 50) and primary osteoarthritis (n = 50) who received the same, unilateral cementless THA. We compared the periprosthetic BMD 5 years after surgery by means of dual energy X-ray absorptiometry (DXA) analysing the seven femoral regions of interest (ROIs) according to Gruen. Within the ONFH group, significantly lower BMD values were found in the ROI 1 and 7 (p

Femoral stem version has a major influence on impingement and early post-operative stability after total hip arthroplasty (THA). The main objective of this study was to evaluate the validity of a novel radiological method for measuring stem version. Anteroposterior (AP) radiographs and three-dimensional CT scans were obtained for 115 patients (female/male 63/72, mean age 62.5 years (50 to 75)) who had undergone minimally invasive, cementless THA. Stem version was calculated from the AP hip radiograph by rotation-based change in the projected prosthetic neck–shaft (NSA*) angle using the mathematical formula ST = arcos [tan (NSA*) / tan (135)]. We used two independent observers who repeated the analysis after a six-week interval. Radiological measurements were compared with 3D-CT measurements by an independent, blinded external institute. We found a mean difference of 1.2° (sd 6.2) between radiological and 3D-CT measurements of stem version. The correlation between the mean radiological and 3D-CT stem torsion was r = 0.88 (p < 0.001). The intra- (intraclass correlation coefficient ≥ 0.94) and inter-observer agreement (mean concordance correlation coefficient = 0.87) for the radiological measurements were excellent. We found that femoral tilt was associated with the mean radiological measurement error (r = 0.22, p = 0.02). The projected neck–shaft angle is a reliable method for measuring stem version on AP radiographs of the hip after a THA. However, a highly standardised radiological technique is required for its precise measurement. Cite this article: Bone Joint J 2015; 97-B:306–11.

Background and purpose Postoperative anterior knee pain is one of the most frequent complications after total knee arthroplasty (TKA). Changes in patellar kinematics after TKA relative to the preoperative arthritic knee are not well understood. We compared the patellar kinematics preoperatively with the kinematics after ligament-balanced navigated TKA. Patients and methods We measured patellar tracking before and after ligament-balanced TKA in 40 consecutive patients using computer navigation. Furthermore, the influences of different femoral and tibial component alignment on patellar kinematics were analyzed using generalized linear models. Results After TKA, the patellae shifted statistically significantly more laterally between 30° and 60°. The lateral tilt increased at 90° of flexion whereas the epicondylar distance decreased between 45° and 75° of flexion. Sagittal component alignment, but not rotational component alignment, had a significant influence on patellar kinematics. Interpretation There are major differences in patellar kinematics between the preoperative arthritic knee and the knee after TKA. Combined sagittal component alignment in particular appears to have a major effect on patellar kinematics. Surgeons should be especially aware of altering preoperative sagittal alignment until the possible clinical relevance has been investigated.

Aims and Objectives: Correct implant alignment is a well known factor for good functional results and increased implant survival after total knee arthroplasty (TKA). However, in present studies only coronal, sagittal and rotational alignment parameters have been considered, while translational parameters, the relative position between the femur and the tibia in medio-lateral, ventro-dorsal and proximo-distal direction are widely neglected. Due to variable mediolateral, proximodistal and ventrodorsal component placement in TKA, we hypothesised changed relative positions between the femoral and tibial bone resulting in a subluxation of knees after TKA. Materials and Methods: In nine Thiel embalmed whole body cadavers without any history of orthopaedic surgeries, fracutres and osteoarthritis, the relative positions between the femoral and tibial bones were measured between 0 and 90° of flexion before and after TKA (DePuy PFC Sigma, CR, fixed bearing) by means of a navigation system (Brainlab 2.6, Feldkirchen). To compare femoral positions before and after TKA, a paired t-test was used. A two-sided p-value of Results: In full extension, the femoral bones shifted 5.7 mm laterally(SD 4.0, p=0.003), and 2.7 proximally (SD 3.1, p=0.030), which decreased up to 90° of flexion to a lateral shift of 3.7 mm (SD 3.5, p=0.006) and proximal shift of 0.9 mm (SD 1.6, p=0.144). The femoral bones were located more dorsal in extension (2.8 mm dorsally (SD 4.8, p=0.113) which changed to a more ventral position in flexion (2.8 mm, SD 4.2, p=0.077). Conclusion: In the present setting, total knee arthroplasty resulted in significant changes of translational positions between the femoral and tibial bones, thus subluxation of knees. Major reasons for that might be a non centered placement of tibial or femoral implants, symmetric implants which do not respect individual anatomy, operative techniques, and large steps between two component sizes. Subluxation might cause an altered tension of the ligaments and consequently change tibiofemoral or patellar kinematics or tensioning of the periarticular soft tissue resulting in pain. However, clinical trials are necessary to evaluate clinical impact of the presented results.

Background Total hip arthroplasty (THA) could be associated with a higher failure rate in patients after osteonecrosis of the femoral head (ONFH) compared to a patient population with primary osteoarthritis prior THA, especially regarding the acetabular component. One major reason could be the compromised acetabular bone quality. Therefore, we performed a retrospective case matched study to assess: (1) is there a difference in periprosthetic bone mineral density between patients with an ONFH prior THA and controls? (2) Do patients with an ONFH prior THA have a lower bone mineral density compared to controls? (3) Which region in the periprosthetic bone stock is more likely to present differences in periprosthetic bone mineral density between both groups? Hypothesis We hypothesized that there is a poorer bone mineral density (BMD) in the periacetabular bone stock in patients with an ONFH prior THA compared to controls receiving a THA due to primary osteoarthritis. Patients and methods We compared the BMD of 50 patients with ONFH to 50 controls with primary osteoarthritis prior THA using the same implant in mean 5 years after surgery by means of dual energy X-ray absorptiometry (DXA). We analyzed 3 acetabular regions of interest (ROIs) according to De Lee and Charnley in a modified measurement technique. Results In ROI 3, representing acetabulum's upper aspect, statistically significant lower BMD values for the ONFH group could be found (P Discussion The results indicate a poorer periacetabular BMD in patients with ONFH prior THA which might be responsible for premature loosening of the acetabular cup in THA. Due to a lack of literature, further clinical investigations are required to confirm our results. Level of evidence Level III: retrospective case control study.