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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.

Das mechanische Alignment (MA) ist ein standardisiertes Vorgehen mit dem Ziel einer neutral ausgerichteten Beinachse. Eine sich naher an die Patientenanatomie orientierende Ausrichtung der Prothese kann ein Ansatz fur bessere klinische Outcomes sein. Die hier vorgestellte Operationstechnik des adjustierten mechanischen Alignments (aMA) ist eine modifizierte Extension-Gap-First-Technik, die die naturliche ligamentare Spannung des Kniegelenks berucksichtigt, sodass ligamentare Releases weitestgehend vermieden werden konnen. Das aMA kann bei primaren und sekundaren Varusgonarthrosen von bis zu 20° angewendet werden. Ziel der Operation ist eine ausgeglichene Bandspannung, die nicht uber Bandreleases, sondern uber eine femorale knocherne Korrektur erreicht wird. TEA und Sulkuslinie werden zur Kontrolle der ligamentbasierten Femurrotation markiert. Fur eine reliable Bandspannung werden die Osteophyten entfernt. Ein quantitativer Bandspanner wird unter groster Sorgfalt aufgespannt, Spaltweite sowie mediale und laterale Bandspannung werden abgelesen. Um eine Streckspaltasymmetrie zu korrigieren, wird, statt des typisch durchgefuhrten medialen Weichteilreleases, die Asymmetrie durch einen speziellen femoralen Schnittblock knochern ausgeglichen. Nun wird der Beugespalt beurteilt, wobei die transversale femorale Rotation der Weichteilspannung folgt. Der Spanner stellt einen rechteckigen Beugespalt bei ausgeglichener Bandspannung ein. Nach finaler Ausbalancierung des Spalts wird die Femurpraparation vollendet und die Probekomponenten werden eingesetzt. Hierbei wird die Rotation der Tibiakomponente durch Einlaufen festgelegt. Die vorgestellte Technik kombiniert eine Measured-Resection-Technik mit der individuellen Bandspannung. Dabei betragt die maximale Abweichung der femoralen Ausrichtung in der Koronarebene von der Neutralausrichtung 2,5°. Um Probleme zu vermeiden, empfiehlt es sich, eine sich an der Patientenanatomie orientierende Komponentenausrichtung uber eine Anpassung der Femurkomponente zu erzielen. Die Measured-Resection-Technik birgt die Gefahr der Flexionsinstabilitat. Durch die Gap-Balancing-Technik kann, prazise proximale Tibiaschnitte vorausgesetzt, eine symmetrische Bandspannung erreicht werden. Beim Ausrichten der Femurkomponentenrotation sollte auf Beugespaltstabilitat und Patellatracking geachtet werden. Langzeitstudien hoher Fallzahl sind notig, um die guten kurzfristigen Ergebnisse der vorgestellten Operationstechnik zu evaluieren.

Aims We report the natural course of Baker’s cysts following total knee arthroplasty (TKA) at short- and mid-term follow-up. Methods In this prospective case series, 105 TKA patients were included. All patients who received surgery had a diagnosis of primary osteoarthritis and had preoperatively presented with a Baker’s cyst. Sonography and MRI were performed to evaluate the existence and the gross size of the cyst before TKA, and sonography was repeated at a mean follow-up time of 1.0 years (0.8 to 1.3; short-term) and 4.9 years (4.0 to 5.6; mid-term) after TKA. Symptoms potentially attributable to the Baker’s cyst were recorded at each assessment. Results At the one-year follow-up analysis, 102 patients were available. Of those, 91 patients were available for the 4.9-year assessment (with an 86.7% follow-up rate (91/105)). At the short- and mid-term follow-up, a Baker’s cyst was still present in 87 (85.3%) and 30 (33.0%) patients, respectively. Of those patients who retained a Baker’s cyst at the short-term follow-up, 31 patients (35.6%) had popliteal symptoms. Of those patients who continued to have a Baker’s cyst at the mid-term follow-up, 17 patients (56.7%) were still symptomatic. The mean preoperative cyst size was 14.5 cm2 (13.1 to 15.8). At the short- and mid-term follow-up, the mean cyst size was 9.7 cm2 (8.3 to 11.0) and 10.4 cm2 (9.8 to 11.4), respectively. A significant association was found between the size of the cyst at peroperatively and the probability of resolution, with lesions smaller than the median having an 83.7% (36/43) probability of resolution, and larger lesions having a 52.1% (25/48) probability of resolution (p < 0.001). At the mid-term follow-up, no association between cyst size and popliteal symptoms was found. Conclusion At a mean follow-up of 4.9 years (4.0 to 5.6) after TKA, the majority (67.0%, 61/91) of the Baker’s cysts that were present preoperatively had disappeared. The probability of cyst resolution was dependent on the size of the Baker’s cyst at baseline, with an 83.7% (36/43) probability of resolution for smaller cysts and 52.1% (25/48) probability for larger cysts. Cite this article: Bone Joint J. 2020;102-B(1):132–136

The aim of this study was to demonstrate, whether the degree of limb alignment correction in varus knee osteoarthritis correlated with an increase in ankle symptoms and to define a cut-off value concerning the degree of correction above which to expect ankle problems. Ninety-nine consecutive patients with preoperative intraarticular varus knee deformities who underwent total knee arthroplasty were retrospectively analyzed. Patients were examined clinically (Knee Society Score, Forgotten Joint Score, Foot Function Index, Range of Motion of the knee and ankle joint, pain scales) as well as radiologically. The mean follow-up time was 57 months. The degree of operative limb alignment correction strongly correlated with the Foot Function Index (R = 0.91, p

Anteroposterior (AP) whole leg radiographs (WLR) in the standing position for assessment of the mechanical leg axis are generally performed preoperatively for the planning of total knee replacement (TKR) and postoperatively to assess the leg axis. The objective of the present study was to investigate whether, if preoperative WLR are available, postoperative AP standard knee radiographs in the standing position are sufficient for calculating the mechanical leg axis. In the present prospective study, the mechanical and the anatomical leg axes were determined on the basis of WLR from 104 patients prior to implantation of a TKR and the difference was calculated. Twelve weeks postoperatively, standing long AP radiographs and WLR were prepared. In addition, the mechanical axis was calculated by adding the preoperative difference between the anatomical and mechanical axis to the anatomical axis from the postoperative AP radiographs. Accuracy, bias and level of agreement for calculated relative to measured mechanical alignment were determined. Mean accuracy of calculated mechanical alignment was 0.5° ± 0.4°, and mean bias was 0.0° ± 0.6° (p = 1.00). Bland–Altman analysis revealed a 95% upper and lower level of agreement of − 1.3° and 1.3°, respectively. A preoperative WLR and a postoperative long AP knee standard radiograph are sufficient to determine the mechanical leg axis after TKR. If these are available, it is possible to do without WLR after TKR, particularly since they involve higher radiation exposure, are time-consuming, and are also prone to errors in the first postoperative weeks. II diagnostic study.

Standardized outcome measures are crucial for the evaluation of different treatment and rehabilitation regimes in patients after total knee arthroplasty (TKA). Performance-based measures are necessary to capture different aspects of physical function. High reliability and agreement of five performance-based measures were hypothesized to differentiate between measurement error and change in test performance. Secondary outcomes are the correlation of performance-based measurements to KSS and WOMAC prior to surgery (baseline) and 10 weeks thereafter (t3). The test–retest reliabilities and agreements of the 1-m walk test, the stair-climbing test, the timed-up-and-go test, the weight-balanced-chair-rising test and the isometric maximum knee extension force in patients undergoing total knee replacements were studied. The intraclass correlation coefficient was calculated and a Bland–Altman analysis performed. The weight-balanced-chair-rising test showed a symmetry at baseline = 0.77, 5 ± 1 days after surgery (t1) = 0.50, 9 ± 1 days (t2) = 0.59 and (t3) = 0.80. All performance tests showed high intraclass correlation coefficients (ICC = 0.81–0.99). The 10-m walk test, stair climbing test, and the timed-up-and-go test showed high agreement in the Bland–Altman analysis. The Bland–Altman analysis for the weight-balanced-chair-rising test and isometric knee extension force indicated high agreement at 5 and 9 days postoperatively, but the relative measurement error increased pre- and 10 weeks postoperatively. In conclusion, symmetry, as an important outcome after TKA, is a reliable and rather unique item that should unquestionably be added to established measurements like walking tests or survey-based function assessment. The implementation of standardized performance-based measures to assess physical function in rehabilitation procedures will help to improve the more objectively based assessment of different rehabilitation protocols. II.

Background The apparently physiological kinematics of the bicruciate-stabilized total knee arthroplasty (BCS TKA) systems have been attributed to the anterior and posterior post-cam mechanism. Although comparisons between TKA designs with either a retained or a sacrificed cruciate ligament have been conducted, we are not aware of any analyses of 2 implants with identical bearing geometry but different cruciate-ligament strategies under equal loading conditions. Knowledge about the kinematic effect of the different cruciate ligament strategies would potentially be valuable to facilitate preoperative planning and decision-making with regard to selecting the most appropriate implant for a patient. Methods This retrospective study included 20 patients: 10 treated with a BCS and 10 treated with a cruciate retaining (CR) TKA. Fluoroscopic analyses during high-flexion activities (unloaded flexion-extension and loaded lunge) were conducted at 24 months postsurgery. All patients completed the Knee Society Score, Forgotten Joint Score, and High-Flexion Knee Score questionnaires preoperatively and postoperatively. Results The BCS cohort showed greater femoral lateral rollback as well as a medial pivot in both activities. In contrast, the CR cohort showed a significant increase in anterior translation on the medial compartment as well as almost absent femoral lateral rollback. Higher clinical scores were observed in the BCS cohort. Conclusions At 24 months postsurgery, despite equal bearing geometry, retention of the posterior cruciate ligament in the CR cohort apparently was insufficient to reduce anterior shift. The BCS cohort showed expected knee joint kinematics; however, the kinematics in this cohort could eventually benefit from a smooth transition between the interchanging surfaces. Further investigation should be focused on the surgical technique and its interaction with the TKA design. Level of evidence Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

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.

Mechanical alignment (MA) is a standardized procedure that aims to achieve a neutrally aligned leg axis. An alignment of the prosthesis closer to the patient's anatomy can be an approach for better clinical outcomes. The surgical technique of adjusted mechanical alignment (aMA) presented here is a modified extension-gap-first technique that takes into account the natural ligamentous tension of the knee joint so that ligamentous releases can be avoided as far as possible.The aMA technique can be used for primary and secondary varus gonarthrosis of up to 20° of varus.The aim of the operation is to achieve a balanced ligament tension through a femoral osseous correction rather than ligament releases. TEA and the sulcus line are marked to control the ligament-based femoral rotation. The osteophytes are removed to ensure a reliable ligament tension. A quantitative ligament tensioner is stretched with great care, and gap width as well as medial and lateral ligament tension are read off. In order to correct an extension gap asymmetry, instead of the typical medial soft tissue release, the asymmetry is compensated by a special femoral cutting block. Now, the flexion gap is assessed, whereby the transverse femoral rotation follows the soft tissue tension. The tensioner adjusts a rectangular flexion gap with balanced ligament tension. After a final balancing of the gaps, the femoral preparation is completed and the trial components are inserted. Here, the rotation of the tibial component is set by repeated flexion-extension cycles.The technique presented combines a measured-resection technique with individual ligament tension. The maximum deviation of the femoral alignment in the coronal plane from the neutral alignment is 2.5°. In order to avoid problems, it is recommended, as with the described technique, to achieve a component alignment based on the patient anatomy by adjusting the femoral component. The measured-resection technique carries the risk of flexion instability. With the gap-balancing technique symmetrical ligament tension can be achieved, assuming precise proximal tibial cuts. When aligning the femoral component rotation, flexion gap stability and patella tracking should be considered. Long-term studies of high case numbers are necessary to evaluate the good short-term results of the presented surgical technique.EINLEITUNG: Das mechanische Alignment (MA) ist ein standardisiertes Vorgehen mit dem Ziel einer neutral ausgerichteten Beinachse. Eine sich näher an die Patientenanatomie orientierende Ausrichtung der Prothese kann ein Ansatz für bessere klinische Outcomes sein. Die hier vorgestellte Operationstechnik des adjustierten mechanischen Alignments (aMA) ist eine modifizierte Extension-Gap-First-Technik, die die natürliche ligamentäre Spannung des Kniegelenks berücksichtigt, sodass ligamentäre Releases weitestgehend vermieden werden können.Das aMA kann bei primären und sekundären Varusgonarthrosen von bis zu 20° angewendet werden.Ziel der Operation ist eine ausgeglichene Bandspannung, die nicht über Bandreleases, sondern über eine femorale knöcherne Korrektur erreicht wird. TEA und Sulkuslinie werden zur Kontrolle der ligamentbasierten Femurrotation markiert. Für eine reliable Bandspannung werden die Osteophyten entfernt. Ein quantitativer Bandspanner wird unter größter Sorgfalt aufgespannt, Spaltweite sowie mediale und laterale Bandspannung werden abgelesen. Um eine Streckspaltasymmetrie zu korrigieren, wird, statt des typisch durchgeführten medialen Weichteilreleases, die Asymmetrie durch einen speziellen femoralen Schnittblock knöchern ausgeglichen. Nun wird der Beugespalt beurteilt, wobei die transversale femorale Rotation der Weichteilspannung folgt. Der Spanner stellt einen rechteckigen Beugespalt bei ausgeglichener Bandspannung ein. Nach finaler Ausbalancierung des Spalts wird die Femurpräparation vollendet und die Probekomponenten werden eingesetzt. Hierbei wird die Rotation der Tibiakomponente durch Einlaufen festgelegt.Die vorgestellte Technik kombiniert eine Measured-Resection-Technik mit der individuellen Bandspannung. Dabei beträgt die maximale Abweichung der femoralen Ausrichtung in der Koronarebene von der Neutralausrichtung 2,5°. Um Probleme zu vermeiden, empfiehlt es sich, eine sich an der Patientenanatomie orientierende Komponentenausrichtung über eine Anpassung der Femurkomponente zu erzielen. Die Measured-Resection-Technik birgt die Gefahr der Flexionsinstabilität. Durch die Gap-Balancing-Technik kann, präzise proximale Tibiaschnitte vorausgesetzt, eine symmetrische Bandspannung erreicht werden. Beim Ausrichten der Femurkomponentenrotation sollte auf Beugespaltstabilität und Patellatracking geachtet werden. Langzeitstudien hoher Fallzahl sind nötig, um die guten kurzfristigen Ergebnisse der vorgestellten Operationstechnik zu evaluieren.

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.

The mechanical axis of the lower limb has shown to vary between different weight-bearing conditions and change after total knee arthroplasty (TKA). The purpose of this study was to investigate the correlation between mechanical axis alignment in standing long-leg radiographs and limb loading after TKA. Mechanical axis of the lower limb and limb loading have been prospectively evaluated in 115 patients 10 days and 3 months after TKA. By the moment of standing long-leg radiography for analysis of the mechanical leg axis, two digital scales separately captured the load of each limb. Mechanical axis changed from an initial − 1° ± 2° valgus alignment to a varus axis of + 1° ± 2° (p

It was hypothesized that malrotation of femoral component in total knee arthroplasty (TKA) will significantly impact clinical outcome. Eighty-eight consecutive patients with primary osteoarthritis of the knee were prospectively evaluated. They received a cemented posterior stabilized TKA (NexGen, Zimmer/Biomet® Inc., Warsaw, IN, USA). The femoral component was placed in 3° of external rotation referenced to the posterior condylar line. Postoperatively, a CT scan was performed to evaluate rotation of femoral component in the transverse plane. SF-36, KSS, and WOMAC, as well as their range of motion was assessed prior to surgery, after 6 and 24 months. Data are presented as mean and standard deviation (SD), as well as range if applicable. Correlation analysis was performed between the placement of the femoral component in the transverse plane and the clinical outcome. Femoral component placement was on average 0.1° [SD 2.5°, range − 6.5° to + 6.5°] referenced to the surgical transepicondylar line showing a wide range between the two landmarks after surgery. After 6 months, WOMAC category ‘physical function’ correlated significantly with femoral component rotation (r = − 0.28, p = 0.007). After 24 months, WOMAC categories ‘physical function’ and ‘pain’ correlated significantly with femoral rotation (r = − 0.41, p

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.

Standing long-leg radiographs allow assessment of the mechanical axis in the frontal plane before and after total knee arthroplasty (TKA). An alteration in loading, and hence in the forces acting on the knee joint, occurs postoperatively. We therefore postulated that the mechanical axis measured in the long-leg standing radiograph would change within the first year after TKA.Standing long-leg radiographs of 156 patients were performed 7 days, 3 months, and 12 months after TKA with determination of mechanical axis of the lower limb.Seven days after surgery, the mechanical axis amounted 0.8° ± 1.7° valgus. Three months after the operation, at 1.3° ± 1.3° varus, it was significantly different (P.001) from the primary measurement. No further alteration in the mechanical axis occurred during the first year after TKA. This difference was even more pronounced (P.001) in patients with a postoperative lack of complete extension. Seven days after surgery, they had a valgus axis deviation of 1.6° ± 1.6°; after 3 months, the measurement amounted 1.2° ± 1.3° varus.Measured by a standing long-leg radiograph, the frontal mechanical axis after TKA changes over time. The predictive power of a standing long-leg radiograph in the first week after surgery is limited because limb loading is altered because of pain and is therefore nonphysiological. The actual mechanical axis resulting after TKA can only be assessed in a standing long-leg radiograph at physiological loading.

Individual implant alignment in total knee arthroplasty (TKA) has seen growing interest over the past years. This study therefore aimed to develop a surgical technique for implant alignment based on native ligament tension, and to present the results obtained using this technique. 25 patients were included in this prospective study. Patient-specific instrumentation (PSI) was used for the resection of the extension gap. Ligament tension was measured after the 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 to 3 months postoperatively. The postoperative whole-leg axis was 2.8° ± 1.6° varus. Patients achieved a flexion of 118° ± 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 ligament tension based femoral implant alignment together with PSI. It was shown to be safe, with encouraging clinical and radiological results. Level of Evidence: Therapeutic study level IV

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.

Combining patient-specific instrumentation (PSI) with a balancer device in total knee arthroplasty (TKA) to achieve functional femoral rotational alignment is a novel technique. The primary goal of this study was to introduce a new method to combine PSI with a gap-balancing technique and to determine the impact of the technique on rotation of the femoral component. Twenty-five primary TKAs (15 women, 10 men) were prospectively studied. All TKAs involved PSI with an associated gap-balancing device. Front plane alignment was performed intraoperatively with the PSI, followed by rectangular, symmetrical extension and creation of a flexion gap using the balancer device to set the femoral rotation. Femoral component rotation was between 3° internal and 6° external rotation versus the transepicondylar axis. There were no postoperative signs of patellofemoral dysfunction. In no cases was the resulting joint line displacement >3 mm. The mean elevation was 1.2 ± 0.9 mm (range 0–3). The leg axis was straight in all cases (±3°), at a mean of 1.6° ± 1.0° varus (range 0°–3° varus). PSI was with the gap-balancing technique was successfully used without affecting anatomical alignment. With the balancer device, PSI can be used more widely than techniques based solely on landmarks, as the soft-tissue tension can be taken into account, thus virtually eliminating flexion instabilities.

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.

Patient-specific instrumentation (PSI) uses 3D preoperative imaging to produce individualized cutting blocks specific to patients’ anatomy and according to the preoperative plan with the aim to reduce the number of mechanical leg alignment (MLA) outliers, to improve implant positioning and to decrease surgery time. The primary purpose of this study was to investigate the efficacy of a specific PSI in comparison with standard instrumentation (SI) in reducing the number of MLA outliers. It was hypothesized that the number of MLA outliers would be significantly lower in the PSI group. A multicenter randomized controlled trial was implemented. There were 59 patients in the PSI group and 66 in the SI group. The absolute number of outliers outside the ± 3° target neutral MLA was compared between the groups with a Chi-square test. As secondary outcomes, the Knee Society Score (KSS) and the Knee Injury and Osteoarthritis Outcome Score (KOOS) were compared between the groups preoperatively and at 90-day follow-up. There were 15 (26.3%) MLA outliers in the PSI group and 8 (12.3%) in the SI group. The number of outliers was not independent from the group ( X 2 (1) = 3.8, p = 0.04; Relative risk = 1.5). Preoperatively, there were no significant differences between the groups when comparing their KSS and KOOS sub-scores. At 90 days postoperatively, the patients in the SI group showed better KOOS-Quality of Life (KOSS-QOL) in comparison with the PSI group (p

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.

While patient-specific instrumentation (PSI) in total knee arthroplasty (TKA) allows for transfer of the preoperative plan onto bony landmarks, the soft tissue balancing is not affected. The goals of this randomized clinical trial were to compare PSI and the measured resection technique (conventional) with PSI and the gap balancing technique. Fifty patients were randomized to TKA with conventional PSI (PSI-S) (n = 25) or to PSI with additional gap balancing (PSI-GB) (n = 25). All patients were clinically examined at 3 and 12 months postoperatively. Data on the range of motion, the Knee Society Score, the Western Ontario and McMasters Universities Osteoarthritis Index, the High-Flexion Knee Score (HFKS), and the Forgotten Joint Score (FJS) were compiled at follow-up. Statistically significant improvements were found for all clinical parameters in the PSI-GB group compared to the PSI-S group at 3 months postoperatively and for FS, FJS, and HFKS at 12 months. However, the relevance of these differences, as well as their effect on long-term outcomes, needs to be evaluated further. In conclusion, patient-specific instrumentation combined with gap balancing yielded good early clinical outcomes.

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.

The purpose of this study was to determine if intraoperative navigation predicted final implant position of total knee arthroplasties (TKAs) performed with patient-specific instrumentation (PSI). We retrospectively reviewed 60 TKAs performed with PSI and imageless navigation. These values were compared to postoperative coronal alignment based on long-leg radiographs, as well as rotation and tibial slope based on CT scans. The intraoperative coronal position of the tibia as measured by the intraoperative navigation indicated a significantly higher deviation from the neutral mechanical axis than the actual final position (P=0.03). Similarly, tibial slope and femoral component rotation measured by intraoperative navigation significantly deviated from the final slope and femoral component rotation (P0.0001). In conclusion, intraoperative navigation of PSI position showed a significantly high deviation from the true final implant position.Level III, therapeutic. See Instructions to Authors for a complete description of levels of evidence.