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Due to the high heterogeneity in outcome measures after total hip arthroplasty (THA), the prospective observational study investigated the relationships between symmetry-based (SBMs), performance-based (PBMs), and functional outcome measures in THA patients to determine necessary or redundant categories of tests. The study material consisted of 24 patients with end-stage hip osteoarthritis scheduled for THA. The patients were examined one day before surgery and consecutively on the 4th day, 9th day, and 10th week postoperatively using the SBMs (weight-bearing chair-rising test, measurements of the maximal isometric torque of the quadriceps muscle); the PBMs (10-m walk, timed up-and-go, and stair-climbing tests); and the functional outcome measure (Harris Hip Score). The results obtained in a given category of tests at different time points were compared, and the correlations between the tests were determined. The reliability of the outcome measures was determined. The results of tests in the studied categories statistically significantly (p < 0.05) improved at the 10th week postoperatively compared to preoperative results. No strong correlations were revealed between the three studied types of outcome measures in THA patients. Therefore, none of them can be considered redundant. It also means that the relevance of symmetry for a core measurement set to describe the domain function in THA patients must be further clarified.

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/m3 was measured during the implantation of 12 total knee arthroplasties (6 × LAF, 6 × 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 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.

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.

Objectives: Baker's cysts are not uncommon in patients eligible for total knee arthroplasty (TKA). There is a paucity of medium-term studies that assess the natural course of Baker's cyst following TKA. In this study, we report the one and five year outcome of patients to elucidate the state[for full text, please go to the a.m. URL], Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2019)

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 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 significantly correlated with the postoperative FFI (R = 0.95, p R = 0.74, p 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 stiff subtalar joint. Level of evidence III.

The knee joint center of rotation is altered in the absence of the anterior cruciate ligament, which leads to substantially higher variance in kinematic patterns. To overcome this, total knee arthroplasty (TKA) designs with a high congruency in the lateral compartment have been proposed. The purpose of this study was to analyze the influence of a lateral pivot TKA-design on in-vivo knee joint kinematics. Tibiofemoral motion was retrospectively addressed in 10 patients during unloaded flexion-extension and loaded lunge using single plane fluoroscopy. During the unloaded flexion-extension movement, the lateral condyle remained almost stationary with little rollback at maximum flexion. The medial condyle exhibited anterior translation during the whole flexion cycle. During the loaded lunge movement, a higher degree of rollback compared to the unloaded activity was observed on the lateral condyle, whereas the medial condyle remained almost stationary. The results showed a clear lateral pivot during the unloaded activity, reflective of the implant's geometric characteristics, and a change to a medial pivot and a higher lateral rollback during the weight-bearing conditions, revealing the impact of load and muscle force. It remains unclear if the kinematics with a lateral TKA design could be considered as physiological, due to the limited knowledge available on native knee joint kinematics.

Background: There is an ongoing debate whether patients with constitutional varus should be restored to neutral mechanical alignment following total knee arthroplasty (TKA). Objective: The aim of this retrospective cohort study is to determine whether mild unintentional postoperative varus alignment (3°–6°) influences TKA outcome in patients with and without preoperative varus alignment due to medial osteoarthritis of the knee. Methods: We analyzed 172 consecutive TKA cases between April 2011 and May 2014. Patients were divided into four groups based on their preoperative and postoperative hip-knee-ankle angles (HKA): preoperative varus ≤ 3° with postoperative varus position ≤ 3° (Group 1, n = 47); preoperative varus >3° with postoperative varus ≤ 3° (Group 2, n = 104); preoperative varus ≤ 3° with postoperative varus malalignment > 3° (Group 3, n = 3); and preoperative varus > 3° with postoperative varus malalignment > 3° (Group 4, n = 18). Patients were followed up until 2 years postoperatively. Results: Knee Society Score and Western Ontario and McMaster University Osteoarthritis Index scores for all study groups increased following TKA, with no postoperative differences at any time point. Group 4 performed significantly better on the Forgotten Joint Score than Group 2 (p = 0.019). Group 4 performed significantly better on the High Flexion Knee Score than Group 2 (p = 0.004) and Group 1 (p = 0.019). All other between-group differences were not statistically significant. Conclusion: Residual postoperative varus alignment of the lower limb does not appear to adversely affect clinical outcome following TKA for varus-type osteoarthritis.

IntroductionThere is a lack of harmonising measures for clinical trials on total joint replacement (TJR) that would allow for results from TJR studies to be compared or pooled. The Outcome Measures in Rheumatology (OMERACT) TJR core domain set is already endorsed among patients and physicians in the USA and Australia. Physiotherapists use different types of measurements compared to orthopaedic surgeons while both make substantial contributions to research in the field of TJR. To achieve consensus on core measurements sets, patients, physiotherapists and orthopaedic surgeons need to achieve consensus on the core domains for TJR trials.Methods and analysisFor this multistage study, first, the OMERACT TJR core domain set survey will be translated to German and validated according to WHO guidelines. Next, the TJR core domain set will be considered for endorsement in different German stakeholder groups including patients, physiotherapists and orthopaedic surgeons.Ethics and disseminationEthical approval for this protocol was given by the ethics committee of the Brandenburg University of Technology Cottbus—Senftenberg (BTU—CS, EK 2019—2). This article is based on the protocol version 2.5 from 6 May 2020. Anonymous data will be presented only. We will publish the results in peer-reviewed publications and at international conferences.Trial registration numberGerman Clinical Trials Registry (DRKS00016015).

Mechanical axis of the lower limb assessed in standing long-leg radiographs was demonstrated to change within the first three postoperative months after total knee arthroplasty (TKA). The underlying mechanism including the influence of limb loading for the change in mechanical axis alignment after TKA has not been evaluated so far. Mechanical axis of the lower limb and limb loading were evaluated in 115 patients 10 days and 12 weeks after TKA. Mechanical axis was measured in standing long-leg radiographs while limb loading was simultaneously assessed using a scale. Absolute and relative limb loading with their correlation to the mechanical axis were calculated. Mechanical axis in patients with postoperative complete extension (n = 100) changed from an initial -0.82° ± 1.9° valgus alignment to a varus axis of +0.6° ± 1.5 (p < 0.01). This change in alignment was accompanied by an increased limb loading from 89.9% 10.7% to 93.0% 7.0% (p < 0.01). The mechanical axis highly/significantly correlated with relative limb loading in both measurements (r = 0.804, p < 0.001 respectively r = 0.562, p < 0.001). These alterations and distinctions were much more pronounced in patients with postoperative incomplete extension. Mechanical axis of the leg significantly changes while limb loading increases within the first three postoperative months after TKA. The postoperative alignment highly correlates with the loading of the lower limb. Therefore, the actual mechanical axis can only be assessed at physiological limb loading in long-leg radiographs at complete extension with full weight bearing.

The purpose of this paper is to present a clinical validation of a novel technology called ’3XPlan’ which allows for 3D prosthesis planning using 2D X-ray radiographs. After a local institution review board (IRB) approval, 3XPlan was evaluated on 25 patients TKA. Pre-operatively, all the patients underwent a CT scan according to a standard protocol. All the CT images were segmented to extract 3D surface models of both femur and tibia, which were regarded as the ground truth. Additionally, 2 X-ray images were acquired for each affected leg and were used in ’3XPlan’ to derive patient-specific models of the leg. For 3D models derived from both modalities (CT vs. X-ray), five most relevant anatomical parameters for planning TKA were measured and compared with each other. Except for tibial torsion, the average differences for all other anatomical parameters are smaller than or close to 3 degrees.

Background There continues to be a lack of evidence to support physiotherapeutic rehabilitation measures after total knee arthroplasty (TKA), especially in the area of functional test procedures, which are indispensable for assessing perioperative physiotherapeutic interventions, including their efficacy. Objective A multi-stage, randomised, controlled study design is concerned with the establishment of an evidence-based perioperative physiotherapeutic treatment programme to evaluate physical functional test procedures with regard to their predictive value and the efficacy of physiotherapeutic interventions. Setting The RCT will be realised in a medical clinic in the department of orthopaedics, sports medicine and rehabilitation. Participants A first stage will include young, healthy subjects (Group A) and subjects who are due to undergo TKA and are then to be treated with a standard rehabilitation programme (Group B). Design Selected promising physical functional test procedures will be tested for their reliability. Inter-tester reliability will be determined in Group A. The test-retest reliability at different perioperative timepoints will be determined in Group B. Measurements The following test procedures will be investigated for reliability: 10-m walk test, timed up and go, three times sit to stand, isometric maximal force of knee extension, stair climbing and the cumulative leg circumference. In addition, these test procedures will be correlated among each other and with the WOMAC and KSS for selected aspects of validity. In a second stage, the reliable test procedures will be applied to investigate selected promising physiotherapeutic interventions. Conclusions The investigation could change perioperative assessments and physiotherapeutic treatment in patients who have undergone TKA.

Aims and Objectives: Baker’s cysts are common in knees with degenerative changes. Common opinion is that most them vanish after treatment of the intraarticular knee disorder. The present study aimed to evaluate the fate of Baker’s cyst and its associated symptoms after TKA. Materials and Methods: In this prospective study, 105 patients with a MRI verified Baker’s cyst, primary OA and an appointment for TKA were included. Three patients were lost to follow-up (two died and one septic TKA removal). Mean age was 70.1 ± 7 years. Ultrasound was performed to evaluate the existing and the gross size of the cyst was performed before and one year (mean 12.3 ± 1.1 months) after TKA. Additionally, Baker’s cyst associated symptoms were recorded Results: After one year, Baker’s cysts were still detected in 85.3% of the patients (n = 87). There was a significant reduction in Baker’s cyst associated symptoms from before (70.6%) to after surgery (31.4%; p < 0.0001). No patients developed new Baker’s cyst associated symptoms. However, out of the 72 patients that reported preoperatively about Baker’s cyst associated symptoms, one year after surgery 44.4% (n = 32) of the patients still complained about Baker’s cyst associated symptoms. The size of Baker’s cysts decreased significantly from pre- (mean 1447 mm2) to postoperative (969 mm2) ultrasound assessment (p < 0.0001). Conclusion: Baker’s cysts vanished only in a small amount of patients (15%) one year after TKA. Nevertheless in this in general considered successful surgery, in close to half of the patients (44.4%) with preoperative Baker’s cyst associated symptoms, these symptoms did not vanish until one year after TKA. Thus, it might be worthwhile to evaluate its treatment options and include them in future treatment plans.

Introduction The proper management of total knee arthroplasty (TKA) in patients with severe deformities regarding the preferable prosthetic design and the required amount of constraint is a controversial subject. In the absence of any high-level clinical evidence, we designed a randomised clinical trial to investigate if rotating hinged (RTH) and constrained condylar knee (CCK) designs yield similar outcomes. Methods and analysis This study is a multicentre, randomised clinical trial including two groups of 85 patients. Patients will be randomised to a CCK knee design group or an RTH knee design group. Patients will be followed for 2 years. The study will be designed as an equivalence trial. The primary study outcome will be the postoperative functional outcome as measured by the self-administered Knee Injury and Osteoarthritis Outcome Score. Secondary outcomes will be postoperative joint awareness during various activities of daily living as measured by the Forgotten Joint Score-12, the Knee Society Score, along with the incidence and location of radiolucent lines using the Knee Society TKA radiographic evaluation system. Ethics and dissemination This study is approved by the ethics committee of the Landesarztekammer Brandenburg ((S 10(a)/2013) from 27.08.2013, amended on 25.04.2016) and will be conducted according to the principles of the World Medical Association Declaration of Helsinki and the ISO14155:2011. Trial registration number DRKS00010539.

Background:Previous studies have shown a high incidence of complications with a bi-cruciate stabilized (BCS) guided-motion total knee arthroplasty (TKA) design, which led to recent modifications of the design by the manufacturer.Objective:The current study was undertaken to assess whether the use of this TKA system with an extension-first surgical technique is associated with a similar rate of short-term adverse outcome as reported in literature.Material and Methods:This retrospective study enrolled 257 consecutive patients (257 knees) undergoing TKA for osteoarthritis of the knee, with the first 153 receiving cemented Journey BCS I implants and the remaining 104 receiving cemented Journey BCS II implants when these became available.Results:Mean follow-up time for the cohort was 24.5 ± 7.8 months (range, 12 - 36 months). There were no cases of stiffness. Incidence of iliotibial friction syndrome was considered low: three (2.0%) knees in the BCS I group and two (1.9%) in the BCS II group (p = 0.676). Five (2.5%) knees presented with mild instability in midflexion, three (2.0%) in the BCS I group and two (1.9%) in the BCS II group (p = 0.676). One patient with a BCS I implant required reoperation for aseptic loosening 23 months postoperatively. At one-year follow-up, there were no clinically relevant differences in any of the clinical outcomes.Conclusion:When used in combination with an extension-first surgical technique, good early functional results with an acceptable rate of complications were obtained with both the original and the updated Journey BCS knee implant.

Background Patient-specific instrumentation in TKA has the proposed benefits of improving coronal and sagittal alignment and rotation of the components. In contrast, the literature is inconsistent if the use of patient-specific instrumentation improves alignment in comparison to conventional instrumentation. Depending on the manufacturer, patient-specific instrumentation is based on either MRI or CT scans. However, it is unknown whether one patient-specific instrumentation approach is more accurate than the other and if there is a potential benefit in terms of reduction of duration of surgery.

A bi-cruciate stabilized (BCS) guided-motion total knee arthroplasty (TKA) design was introduced to improve knee kinematics by more closely approximating those of a normal knee. Previous studies have shown a high incidence of complications with this implant type, which led to recent modifications of the design by the manufacturer. The current study was undertaken to assess whether the use of a guided-motion knee system with an extension-first surgical technique is associated with a similar rate of short-term adverse outcome as reported in literature. The secondary aim was to assess if there were any differences between the original and modified implant designs. This retrospective study enrolled 204 consecutive patients (204 knees) undergoing TKA for osteoarthritis of the knee, with the first 154 receiving cemented Journey BCS I implants and the remaining 51 receiving cemented Journey BCS II implants when these became available. At follow-up, patients were tested for the presence of iliotibial friction syndrome (ITB-F) and midflexion instability. Knee score and function score were taken preoperatively, at one year, and at final follow-up. Outcome data between the two implant types were compared using the Mann-Whitney test. No patients were lost to follow-up. Mean follow-up time for the cohort was 24.5 ± 7.8 months (range, 12 - 36 months). There were no cases of stiffness (flexion < 90°). Incidence of ITB-F syndrome was considered low: three (2.0%) knees in the BCS I group and two (3.9%) in the BCS II group (p = 0.367). Five (2.5%) knees presented with mild instability in midflexion, three (2.0%) in the BCS I group and two (3.9%) in the BCS II group (p = 0.367). One patient with a BCS I implant required reoperation for aseptic loosening 23 months postoperatively. At one-year follow-up, there were no significant differences in range of motion, knee score, or function score. When used in combination with an extension-first surgical technique, good early functional results with an acceptable rate of complications were obtained with both the original and the updated Journey BCS knee implant. Long-term follow-up studies are needed to confirm our findings.

AIM: To introduce the navigation system of software and instruments designed specifically for revision total knee arthroplasty (TKA). METHODS: We present an imageless navigation system for revision TKA, with optical point and tracker identification to assess kinematic and anatomical landmarks. The system automatically positions the cutting guides with a motorized cutting unit. The cutting unit is placed on the distal femur with a femoral clamp and acts as a rigid body and the base for all femoral cuts. The surgical technique for using the navigation system for revision TKA is based on the technique used in primary TKA. However, there are some important differences. The most notable are: (1) differences in estimation of the position of the primary implant relative to the bone and the mechanical axes; (2) the specific possibilities the revision navigation software offers in terms of optimal joint level positioning; and (3) the suggested “best fit” position, in which the clock position, stem position and offset, femoral component size, and mediolateral position of the femoral component are taken into account to find the optimal femoral component position. We assessed the surgical technique, and accompanying software procedural steps, of the system, identifying any advantages or disadvantages that they present. RESULTS: The system aims to visualize critical steps of the procedure and is intended as a tool to support the surgeon in surgical decision-making. Combining a computer-assisted cutting device with navigation makes it possible to carry out precise cuts without pinning. Furthermore, the femoral clamp provides a stable fixation mechanism for the motorized cutting unit. A stable clamp is paramount in the presence of periarticular bony defects. The system allows the position of the primary implant relative to the bone and mechanical axes to be estimated, at which point any malalignments can be corrected. It also offers an optimal joint level position for implantation, and suggests a “best fit” position, in which the clock position, stem position and offset, femoral component size, and mediolateral position of the femoral component are considered. The surgeon can therefore make decisions intraoperatively to maximise alignment and, hence, outcomes. Based on the intraoperative findings of joint stability, the surgeon can modify the preoperative plan and switch from a constrained condylar system to a hinged version, or vice versa. CONCLUSION: The system is flexible and easy to learn and allows improvements in workflow during TKA.

Aims and Objectives: The use of patient-specific instruments (PSI) in total knee arthroplasty (TKA) has seen growing interest over the past years. A potential disadvantage of PSI is that functional implant alignment is not applicable in this technique. This study therefore aimed to develop a surgical technique for ligament-balanced implant alignment based on PSI, and to present the results obtained using this technique. Materials and Methods: 25 patients were included in this prospective study. PSI was used for the resection of the extension gap. Ligament tension was measured after removal of all accessible osteophytes. In the event of asymmetry, the distal femur resection was adjusted up to 2.5° using an adjustable cutting block. The aim was to achieve a symmetrical extension gap without release, not a neutral leg axis. Femoral rotation was aligned on the basis of ligament tension. Patients were followed up 3 months postoperatively. Results: The postoperative whole-leg axis was 2.8°±1.6° varus. Patients achieved a flexion of 118.9°±9°, a Knee Score of 91.5±3.2 and a Function Score of 86.8±8.3 points. 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.