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Purpose: Flexion in a stiff total knee arthroplasty (TKA) can be improved by manipulation under anaesthesia (MUA). Although this intervention usually results in an improvement in range of motion, the expected result is not always achieved. The purpose of this study is to determine which factors affect range of motion after manipulation in patients with a stiff total knee.Methods: After exclusion (n = 22), the data of 158 patients (138 knees) with a stiff knee after TKA who received a manipulation under anaesthesia between 2004 and 2014 were retrospectively analysed. Pre-, peri- and post-operative variables were identified and examined for their influence on flexion after the manipulation using Kruskal-Wallis and Mann-Whitney U tests and Spearman correlations.Results: After MUA, a mean improvement in flexion of 30.3° was observed at the final follow-up. Preoperative TKA flexion, design of TKA and interval between TKA procedure and MUA were positive associated with an increase in flexion after MUA. MUA performed 12 weeks or more after TKA procedure deteriorated the outcome.Conclusions: Three factors, pre-TKA flexion type of prosthesis and interval between TKA procedure and manipulation under anaesthesia, were found to have impact on flexion after TKA and MUA were identified. Results are expected to be inferior in patients with low flexion before TKA procedure or with a long interval (>12 weeks) between the TKA procedure and the manipulation under anaesthesia.Level Of Evidence: IV. [ABSTRACT FROM AUTHOR]

Background: Most knee surgeons have believed during TKA neutral mechanical alignment should be restored. A number of patients may exist, however, for whom neutral mechanical alignment is abnormal. Patients with so-called "constitutional varus" knees have had varus alignment since they reached skeletal maturity. Restoring neutral alignment in these cases may in fact be abnormal and undesirable and would likely require some degree of medial soft tissue release to achieve neutral alignment.Questions/purposes: We investigated what percentage of the normal population has constitutional varus knees and what are the contributing factors.Subjects and Methods: We recruited a cohort of 250 asymptomatic adult volunteers between 20 and 27 years old for this cross-sectional study. All volunteers had full-leg standing digital radiographs on which 19 alignment parameters were analyzed. The incidence of constitutional varus alignment was determined and contributing factors were analyzed using multivariate prediction models.Results: Thirty-two percent of men and 17% of women had constitutional varus knees with a natural mechanical alignment of 3° varus or more. Constitutional varus was associated with increased sports activity during growth, increased femoral varus bowing, an increased varus femoral neck-shaft angle, and an increased femoral anatomic mechanical angle.Conclusions: An important fraction of the normal population has a natural alignment at the end of growth of 3° varus or more. This might be a consequence of Hueter-Volkmann's law. Restoration of mechanical alignment to neutral in these cases may not be desirable and would be unnatural for them. [ABSTRACT FROM AUTHOR]

Unlabelled: There is an ongoing debate whether gender differences in the dimensions of the knee should influence the design of TKA components. We hypothesized that not only gender but also the patient's morphotype determined the shape of the distal femur and proximal tibia and that this factor should be taken into account when designing gender-specific TKA implants. We reviewed all 1000 European white patients undergoing TKA between April 2003 and June 2007 and stratified each into one of three groups based on their anatomic constitution: endomorph, ectomorph, or mesomorph. Of the 250 smallest knees, 98% were female, whereas 81% of the 250 largest knees were male. In the group with intermediate-sized knees, female knees were narrower than male knees. Patients with smaller knees (predominantly female) demonstrated large variability between narrow and wide mediolateral dimensions irrespective of gender. The same was true for larger knees (predominantly male). This variability within gender could partially be explained by morphotypic variation. Patients with short and wide morphotype (endomorph) had, irrespective of gender, wider knees, whereas patients with long and narrow morphotype (ectomorph) had narrower knees. The shape of the knee is therefore not only dependent on gender, but also on the morphotype of the patient.Level Of Evidence: Level I, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Post-steroid septic arthritis can be treated with irrigation pump assisted arthroscopic synovectomy. The high-intra-articular fluid pressures can force the pyogenic fluid into a pre-existing Baker's cyst. The cyst can rupture and with the pre-existing steroid induced immune-suppression, the calf abscess will be hard to control. Therefore, thorough investigation with an ultrasound-guided aspiration followed by an early drainage of the collection is warranted and mandatory. Close monitoring for the development of a deep thrombosis of the popliteal vein is required. [ABSTRACT FROM AUTHOR]

Background: Septic arthritis after arthroscopic anterior cruciate ligament reconstruction is a rare complication. In the literature, several different managements are proposed. Hypothesis: The graft can be retained during treatment of a septic arthritis after anterior cruciate ligament reconstruction. Study Design: Case series; Level of evidence, 4. Methods: A retrospective analysis of knee joint infections occurring after arthroscopically assisted anterior cruciate ligament reconstructions was conducted. Fifteen patients were treated for postoperative septic arthritis of the knee after anterior cruciate ligament reconstruction between 1996 and 2005. All patients underwent an urgent extensive arthroscopic debridement (wash-out and synovectomy) and parenteral antibiotics and oral antibiotics subsequently. Repetitive wash-outs were performed if necessary. The average time at follow-up for our series was 58 months (range, 9-99 months). Results: Only 1 graft was removed during debridement because it was nonfunctional. All other patients retained their anterior cruciate ligament reconstruction. There was no reinfection. There were 2 traumatic reruptures. We evaluated 11 patients: in 6 patients the Lachman test showed a translation of more than 3 mm, but all patients had a firm endpoint and there was no subjective instability. Early signs of radiological degeneration were seen in 3 patients. The value for the Lysholm knee scoring scale was 83, on average, ranging from 57 to 100. Regarding the International Knee Documentation Committee score, 2 patients had a final evaluation of normal, 7 patients nearly normal, and 2 patients abnormal. Conclusion: The graft can be retained during treatment of septic arthritis after anterior cruciate ligament reconstruction. [ABSTRACT FROM AUTHOR]

Total knee arthroplasty is today a successful procedure in relieving pain and functional restoration of patients with advanced knee disease. Our knowledge on indications, surgical technique and prosthetic design have evolved over the past years to such an extent that a consistent and durable outcome can be obtained in the majority of cases. Some controversies that were debated in the past have today been resolved; others are still open for discussion.In this paper, a general overview on the current 'state of the art' in primary knee arthroplasty is given. [ABSTRACT FROM AUTHOR]

Introduction: Prevalence of unexpected positive intraoperative cultures (UPIC) in revision total knee arthroplasty (TKA) is reported to be 8.32% with largely varying findings in individual studies (5.92-62.07%) due to a heterogeneity in preoperative diagnostic work-up and diagnostic criteria for periprosthetic joint infection (PJI). When diagnosed as unsuspected PJI, re-revision rate is reported to be as high as 18.45% compared to 2.94% in patients with UPIC classified as contamination (p = 0.0237). We performed a monocentric retrospective analysis of revision TKA surgery to determine prevalence of UPIC, risk of developing a subsequent PJI and re-revision rate after 24 months compared to those without UPIC., Materials and Methods: All presumed aseptic total knee revision procedures from 2008 until 2017 were retrospectively reviewed. Single stage femorotibial revisions of TKA with at least 3 intraoperative cultures and a minimum follow-up of 24 months were included, whereas partial revisions or revisions from unicompartimental knee prosthesis to TKA were excluded. Demographic data were collected as well as initial reason for revision, preoperative aspiration results, micro-organism identified and postoperative antibiotics' administration. Primary outcome was survival rate after 24 months with differentiation based on UPIC interpretation: sterile, contamination, unsuspected PJI., Results: Of 256 included cases, 75 (29.3%) were found to have at least 1 UPIC during revision surgery, 72% of whom a single UPIC was found. Thirty-four cases (13.28%) were interpreted as unsuspected PJI and therefore treated with antibiotics. In total, 13 of the 256 patients (5.08%) had to be re-revised during follow-up with 7 PJI (2.73%), none of them developing reinfection defined as PJI with the same microorganism. A statistically significant trend towards earlier failure in the unsuspected PJI group compared to the contaminant group was not observed. However, a higher incidence of re-revisions attributed to septic reasons was noted in the former group., Conclusions: Presence of UPIC in presumed aseptic revision TKA does not correlate with a lower survival rate, but a higher incidence of subsequent PJI was observed in cases interpreted as unsuspected PJI., Competing Interests: Declarations. Competing interests: The authors have no competing interests to declare that are relevant to the content of this article., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Patellofemoral pain, maltracking and instability remain common and challenging complications after total knee arthroplasty. Controversy exists regarding the effect of kinematic alignment on the patellofemoral joint, as it generally leads to more femoral component valgus and internal rotation compared to mechanical alignment. The aim of this systematic review is to thoroughly examine the influence of kinematic alignment on the third space., Methods: A systematic search of the Pubmed, Cochrane and Web of Science databases was performed to screen for relevant articles published before 7 April 2024. This led to the final inclusion of 42 articles: 2 cadaveric, 9 radiographic, 12 computer simulation and 19 clinical studies. The risk of bias was evaluated with the risk of bias in non-randomised studies - of interventions tool as the lowest level of evidence of the included clinical studies was IV. The effects of kinematic alignment on patellar kinematics and kinetics, trochlear anatomy reconstruction and patellofemoral complication rate were investigated., Results: Kinematic alignment closely restores native patellar kinematics and kinetics, better reproduces native trochlear anatomy than mechanical alignment and leads to a 0%-11.4% incidence of patellofemoral complications. A more valgus joint line of the distal femur can cause lateral trochlear undercoverage and a trochlear angle orientation medial to the quadriceps vector when applying kinematic alignment, both of which can be solved by using an adjusted design with a 20.5° valgus trochlea., Conclusion: Kinematic alignment appears to be a safe strategy for the patellofemoral joint in most knees, provided that certain precautions are taken to minimize the risk of complications., Level of Evidence: Level IV clinical studies, in vitro research., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Purpose: The purpose of this study was to investigate the influence of increasing the tibial boundaries in functional alignment on femoral component orientation in total knee arthroplasty (TKA)., Methods: A retrospective review of a database of robotic-assisted TKAs using a digital joint tensioning device was performed (BalanceBot®; Corin). A total of 692 TKAs with correctable deformity were included. Functional alignment with a tibia-first balancing technique was simulated by performing an anatomic tibial resection to recreate the native medial proximal tibial angle within certain boundaries (A, 87-90°; B, 86-90°; C, 84-92°), while accounting for wear. After balancing the knee, the resulting amount of femoral component outliers in the coronal and axial plane was calculated for each group and correlated to the coronal plane alignment of the knee (CPAK) classification., Results: The proportion of knees with high femoral component varus (>96°) or valgus (<87°) alignment increased from 24.5% (n = 170) in group A to 26.5% (n = 183) in group B and 34.2% (n = 237) in group C (p < 0.05). Similarly, more knees with high femoral component external rotation (>6°) or internal rotation (>3°) were identified in group C (33.4%, n = 231) than in group B (23.7%, n = 164) and A (18.4%, n = 127) (p < 0.05). There was a statistically significant (p < 0.01) overall increase in knees with both femoral component valgus <87° and internal rotation >3° from group A (4.0%, n = 28) to B (7.7%, n = 53) and C (15.8%, n = 109), with CPAK type I and II showing a 12.9- and 2.9-fold increase, respectively., Conclusion: Extending the tibial boundaries when using functional alignment with a tibia-first balancing technique in TKA leads to a statistically significant higher percentage of knees with a valgus lateral distal femoral angle < 87° and >3° internal rotation of the femoral component, especially in CPAK type I and II., Level of Evidence: Level IV., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Purpose: Strategies to further improve patient satisfaction after total knee arthroplasty include the introduction of new alignment philosophies and more precise instruments such as navigation and robotics. The aim of this study was to investigate the effect of a combination of image-based robotic assistance and the use of modern alignment strategies on the resulting joint line obliquity as well as femoral component rotation and to compare this between varus, neutral and valgus knees., Methods: This retrospective study included 200 patients who received a robotic-assisted total knee arthroplasty (MAKO ® , Stryker) using functional alignment between 2018 and 2020. The patients were divided into a varus (103 patients), neutral (57 patients) and valgus (40 patients) group. The intraoperatively recorded bone cuts and resulting joint line obliquity were identified and compared to values obtained with a robotic computer simulation of kinematic alignment., Results: The mean femoral coronal alignment of the varus, neutral and valgus group, respectively, equalled 0.5° (± 1.1°), 1.1° (± 0.8°) and 1.6° (± 0.7°) of valgus with functional alignment and 2.1° (± 2.1°), 4.1° (± 1.7°) and 6.2° (± 1.7°) of valgus with kinematic alignment. The mean femoral axial alignment of the valgus group resulted in 0.8° (± 2.0°) of internal rotation with functional alignment and 3.9° (± 2.8°) of internal rotation with kinematic alignment. Overall, 186 knees (93%) could be balanced while respecting certain safe zones by using functional alignment as opposed to 54 knees (27% and none in the valgus group) when applying kinematic alignment. Kinematic alignment led to a combination of femoral component valgus and internal rotation of more than 3° in 22 valgus knees (55%), 10 neutral knees (18%) and 3 varus knees (3%) compared to none in each group when applying functional alignment with safe zones., Conclusions: Robotic-assisted kinematic alignment leads to a combination of excessive valgus and internal rotation of the femoral component in valgus and to a lesser extent also in neutral knees when compared with functional alignment., Level of Evidence: IV., (© 2023. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Purpose: Despite widespread adoption of NAVIO robotic-assisted total knee arthroplasty (NAVIO RATKA) in clinical practice, clinical outcome in terms of adverse events and complications remains unclear. The purpose of this study was to compare adverse events, length of stay, surgical time, hemoglobin drop, early readmission rate and revision rate between conventional TKA (CTKA) and NAVIO RATKA., Methods: This single-centre retrospective cohort analysis compared 230 NAVIO RATKA patients to 489 CTKA patients with a minimal follow-up of 12 months. Baseline demographic and comorbidity parameters were collected, as well as length of stay, revision rate and reason for revision, early readmission rate (< 6w) and reason for readmission, post-operative hemoglobin levels, adverse events, surgical time and operating room time. Data were compared using Mann-Whitney U test for continuous data without normal distribution and ordinal data, categorical variables were compared using the Chi-square or Fisher exact test., Results: There were no clinically relevant baseline demographic or comorbidity differences between groups. CTKA had shorter length of stay than NAVIO RATKA (5.0 days vs 5.4 days, p = 0.010) but trended towards a higher reoperation rate (4.1% vs 1.7%, p = .144, n.s). No differences were found in hemoglobin drop, readmission rate or overall incidence of adverse events, but CTKA showed more hematoma formation (1.6% vs 0%, p = .044) and higher incidence of periprosthetic joint infection (PJI) (1% vs 0%, p = n.s.), whilst NAVIO RATKA showed more periprosthetic fractures and persistent wound drainage (0.4% vs 2.2%, p = .038 and 0.6% vs 4.3%, p = .001, respectively). Surgical time remained significantly longer in NAVIO RATKA during all 230 cases (87 min vs 67.6 min) and showed a continuous downward trend., Conclusions: This study further validates the usage of NAVIO RATKA as a safe method to perform TKA, with comparable short term outcomes to CTKA in terms of early revisions and adverse events. Surgeons should be mindful of the differing adverse event profile in NAVIO RATKA and adjust their patient selection accordingly to ensure optimal outcomes. In addition, surgeons using NAVIO RATKA should expect a linear learning curve and a surgical time exceeding that of CTKA., Level of Evidence: Level III (therapeutic retrospective cohort study)., (© 2023. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

At the time of return-to-sport, anterior cruciate ligament reconstructed athletes still show altered neuromechanics in their injured leg during single leg hopping tasks. Part of these alterations can be magnified when these athletes are fatigued. So far, little is known whether fatigue-induced landing alterations persist after return-to-sport. Therefore, the aim of this study was to evaluate whether these alterations persist in the six months following return-to-sport. Sixteen anterior cruciate ligament reconstructed athletes performed five unilateral hop tasks before and after a fatigue protocol. The hop tasks were executed at three different time points (return-to-sport, 3 and 6 months post-return-to-sport). A 2-by-3 repeated measures ANOVA was performed to evaluate whether fatigue-induced landing alterations persisted 3 and 6 months following return-to-sport. At 6 months following return-to-sport, fatigue still induces a reduction in hamstring medialis activation and an increase in the knee abduction moment during a vertical hop with 90-degree inward rotation. Most fatigue-induced landing alterations present at the time of return-to-sport normalize after resumption of sports activities. However, a larger knee abduction moment in the injured leg after resumption of sports activities can still be observed., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Introduction: The aim of this study was to examine if robotic-assisted total knee arthroplasty (RATKA) is cost- and time-effective in terms of implant stock and perioperative parameters, as optimizing perioperative efficiency may contribute to value-based care., Materials and Methods: Four hundred thirty-two consecutive patients who received primary total knee arthroplasties (TKAs) from May 2017 to March 2020 in a regional hospital were included in this study. Operating room time (OR time), surgical time, number of trays, insert thickness, and length of stay (LOS) were assessed and compared for a cohort group with navigation-assisted procedures to a group with robotic-assisted procedures (MAKO, Stryker, USA). Prediction of implant size was assessed for the robotic-assisted group. The Mann-Whitney U test was used for comparisons between groups when the normality assumption was not met. Categorical variables were assessed using the Fisher's exact test. p < 0.05 was considered statistically significant., Results: In the RATKA group, we noticed a significant mean reduction of 11 min in total OR time (p < 0.001), the use of thinner insert (p < 0.001), and a shorter mean length of stay of 1 day (p < 0.001). Compared to the navigation group, surgical time was not significantly longer, nor clinically relevant (0.238). In 76.9% of the robotic-assisted cases, the estimated implant size was equal to the final size and in all other cases, the preoperative implant size was oversized., Conclusion: The introduction of the MAKO robotic-assisted total knee arthroplasty resulted in a gain in operating room time, a thinner and more predictable insert thickness, a shorter length of stay in hospital, and less instrumentation compared to navigation-assisted procedures. Level of evidence Level III, Retrospective cohort study., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Recurrent patellar dislocation is most commonly treated with an isolated medial patellofemoral ligament reconstruction using autograft tissue. Harvest and fixation of these grafts have some theoretical disadvantages. With this Technical Note, we aim to describe a simple reconstruction of the medial patellofemoral ligament using high-strength suture tape with a soft-tissue fixation on the patellar side and an interference screw fixation on the femoral side, avoiding some of these possible disadvantages., (© 2023 The Authors.)