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Background and Objective: It is evident from the national joint registries that numbers of revision knee arthroplasty operations are rising. The aim of this article is to introduce a new robotic-assisted approach in UKA to TKA revision arthroplasty and investigate the alignment accuracy, implant component use and surgery time and to compare it to primary robotic-assisted TKA arthroplasty., Methods: This retrospective, case-control study included patients undergoing image-less robotic-assisted revision arthroplasty from UKA to TKA (n = 20) and patients undergoing image-less robotic-assisted primary TKA (control group, n = 20) from 11/2018 to 07/2020. The control group was matched based on the BMI and natural alignment. Comparison of groups was based on postoperative alignment, outlier rate, tibial insert size, lateral bone resection depth, incision-to-wound closure time. All surgeries were performed by a single senior surgeon using the same bi-cruciate stabilizing TKA system. Statistical analysis consisted of parametric t‑testing and Fisher's exact test with a level of significance of p < 0.05., Results: The two groups showed no differences in mean BMI, natural alignment (p > 0.05) and mean overall limb alignment. No outlier was found for OLA and slope analysis. The smallest insert size (9 mm) was used in 70% of the cases in the revision group (n = 14) and in 90% of the cases in the primary group (n = 18, p = 0.24), distal femoral and tibial resection depth showed no statistical difference (p > 0.05). The incision to wound closure time was longer in the revision group but showed no significant difference., Conclusion: Image-less robotic-assisted revision arthroplasty from UKA to TKA showed a comparable surgery time, and alignment accuracy in comparison to primary robotic-assisted TKA. Comparable bone preservation and subsequent tibial insert size use was observed for both groups., (© 2021. The Author(s).)

End-of-stem pain after knee and hip arthroplasty with diaphyseal supportive stems is a frequently overlooked and potentially underestimated complication. A commonly recurring clinical phenome is the symptom-free interval after surgery of weeks to months, with new onset of symptoms under stress only later. The patient is often again reliant on walking sticks. End-of-stem pain is a diagnosis of exclusion. Pain is projected into the tip of the stem, and if differential diagnoses such as loosening are excluded, then the patient might be treated with a "bending-plate". Since bone cement has a similar elastic modulus to human cortical bone, a change of method to a cemented implant can also be expedient. In the primary situation, in addition to cemented stems, the use of "split-stems" could be useful. After revision surgery of any kind, a timely cessation of pain confirms the diagnosis.

Background: Kinematic alignment is a philosophy for individual knee prosthesis implantation in a three-dimensional view. The key of the concept is to understand the femoral flexion-extension axis as the centre of a cylinder within the posterior condyles. This axis defines the knee in three dimensions over the entire range of motion. The tibia follows the femur, is balanced on the knee in extension and flexion, and shows individual laxities in flexion and deep flexion., Impacts: As a consequence, limbs will be reconstructed along their constitutional leg axis, which in most patients is different to a straight hip-knee-ankle centre axis. The method aims at perfectly reconstructing the natural joint lines, which in many patients leads to the natural oblique joint lines. This results in considerable advantages, as the natural stability of the knee is restored, and native patella kinematics are maintained. From a static view, polyethylene and the implant-bone interface may be vulnerable to mechanical overloading due to altered adductor moments. However, a growing body of evidence shows that naturally oriented knee joints show a more balanced loading pattern. Moreover, dynamic gait patterns actually show the mechanism of even reduced knee adductor moments, explaining the clinical results of up to 10 years follow up.

Background: Kinematic alignment recently became an alternative alignment option for total knee arthroplasty (TKA). Beside previous studies assessing mechanical alignment in comparison to unintentional malalignment of TKA in terms of implant survival and clinical outcome, more and more studies have focused on the direct comparison of intentional kinematic alignment with mechanical alignment of the prosthesis. In the past 5 years the number of studies with respect to kinematic alignment has risen from 11 to 91 studies., Aim: The aim of this review article is to give a narrative overview of the current literature in the debate concerning kinematic and mechanical alignment in TKA.

With increasing numbers of primary knee arthroplasties, the relevance and frequency of prosthesis replacement operations are increasing with a time lag. Two-zone anchoring is important. Due to bony defects, the articular surface can often no longer be used as a possible anchoring zone, so the fixation must take place in the metaphyseal and diaphyseal area of the bone. If, for various reasons, the defect is too pronounced for regular care, individually-manufactured implants can be used. These are produced on the basis of a preoperative CT as part of a two-stage change using industrial 3D printers and so-called additive manufacturing.

Introduction: Femoroacetabular impingement of the hip is considered a prearthrotic deformity, which should be treated at an early state to prevent complications., Material: This video demonstrates the arthroscopic-assisted mini-open technique for the treatment of femoroacetabular impingement of the hip. In the case presented a combined Pincer and Cam-deformity is treated with rim trimming, translabral labral refixation with two suture anchors and reconstruction of the head-neck junction., Conclusion: The arthroscopic-assisted mini-open technique is a safe and reproducible procedure for treatment of femoroacetabular impingement. It provides an alternative to hip arthroscopy and an additional treatment option in the portfolio of hip surgeons.

Introduction: Over the past decades many innovations were introduced in total knee arthroplasty (TKA) focusing on implant longevity and higher procedural precision; however, there are still a high number of dissatisfied patients. It was reported that better anatomical alignment may result in improved patient outcome; however, current technologies have limitations to achieve this. The aim of this video article is to describe the technique of individualized alignment in TKA with the use of image-based robotic assistance., Methods: The technology is based on an individual patient knee model computed from segmented computed tomography (CT) scans. A preoperative planning of prosthesis position is conducted following the principle of kinematic alignment. Intraoperatively the soft tissue envelope is recorded and the computer predicts the gap balance based on the virtual planning. The prosthesis position is then adapted to achieve balanced gaps and to avoid soft tissue release. This technique is shown in a cadaver operation and clinical examples of two patients are described., Results: With the combination of anatomically oriented prosthesis positioning and minor adaptations with respect to the soft tissue, an individualized alignment is achieved with reduced need of soft tissue release. The robotic-assisted surgery guarantees a precise implementation of the planning. The initial experience showed a promising outcome in short-term follow-up.

Background: There are still a high number of dissatisfied knee arthroplasty patients. This situation has not changed much for decades, despite many innovations focusing on implant longevity and higher procedural precision. In this context, there is a growing discussion on possible systematic errors made in knee arthroplasty, especially regarding the alignment philosophy of the implants., Objective: It was reported that a more anatomical alignment might result in improved patient outcome. However, current technologies have severe limitations to achieving optimized and individual alignment. In this context, the aim of this manuscript was to assess whether image-based robot-guided knee arthroplasty might represent an opportunity for achieving individualized alignment., Methods: The literature on this subject was evaluated and analyzed. Furthermore, research projects and expert recommendations were discussed., Results: The precision of preoperative planning is higher with robotic techniques than with other computer-assisted or manual technologies. In addition, the individual soft tissue situation of the patient is taken into account and the prosthesis position is optimized. This ensures optimum soft tissue balancing and stability of the prosthesis., Conclusion: Modern robot-assisted systems are the mechanical bridge between imaging and patient. This technique provides objective control over the results produced with alternative alignments. This applies to both the prosthesis position itself and the resulting soft tissue balancing.

Background: The story of ShapeMatch® custom-fit cutting guides for primary total knee arthroplasty (TKA) is special compared to other available techniques. First, it was the first such patient-specific instrument (PSI) on the market. Second, the underlying philosophy of kinematic alignment is unique compared to other competitors. Finally, it is the only PSI technique that has been withdrawn from the market., Objectives and Methods: The objective of this paper is to summarize the history of the ShapeMatch® technology and to review the current literature regarding clinical evidence for kinematically aligned TKA., Results and Conclusions: In the recent literature, faster rehabilitation, better knee function and higher patient satisfaction are described for kinematically aligned TKA compared to conventional alignment. However, there is also evidence for inaccuracies by using the PSI technology as a possible cause of treatment failures. Due to those problems, this technology was recalled from the market. As an alternative method to achieve kinematic alignment in TKA, manual as well as computer-assisted techniques are currently under development and are discussed here.

Background: We report an unusual case of a 38-year-old physically active patient, who suffered a Ewing sarcoma during adolescence and was therefore treated with a tumor endoprostheses ex domo (replacement of distal femur and proximal tibia). Since then he had undergone a couple of surgical interventions for revision and is currently suffering from persistent pain in the leg concerned. An aseptic loosening of the tibial component was evident after radiologic examinations. Because he had suffered for so long our patient refused further surgery to retain the affected limb and he preferred amputation., Objectives: We would have taken the risk of a femoral residual limb that is much too short compared with a classical above-knee amputation. In this regard we saw difficulties in exoprosthetic treatment with functional limitations that could easily have influenced the outcome negatively., Method: Consequently, we decoupled the tibial component from the femoral one within the knee joint and thus performed a knee disarticulation leaving the femoral component., Results: Postoperatively, we found a mostly harmonious gait pattern with a pure mechanical interim prosthesis regarding time-distance parameters, which may be even further improved with the final prosthesis. Sagittal joint angles are comparable to conventionally knee exarticulated ones., Discussion: To date, no comparable case of such an alloarthroplasty, which could regain mobility with an exoprosthetic treatment has been highlighted in the literature. In the result, a knee disarticulation within the area of a knee arthroplasty leaving the femoral component is not inferior to"ordinary" knee disarticulation.

Background: Against the background that 20 % of patients are dissatisfied after total knee arthroplasty, there is ongoing controversy about optimal alignment. In this context, orientating the prosthetic components to the natural kinematic axes of the knee appears to be an interesting new concept., Methods: The objective of this paper is to provide a critical review of the current literature and our own research data regarding the concept of kinematically aligned total knee arthroplasty with the current evidence base and potential limitations., Results and Discussion: In the recent literature faster rehabilitation, better knee function, and higher patient satisfaction are described compared to conventional alignment, even if the postoperative alignment deviates more than 3° from the mechanical axis. However, the technique may not be suitable for every patient and pathology, and further research is necessary to set the correct indication.

Background: It is well known that morbidity rates of arthroplasties are inversely related to procedure volume. In the department of orthopaedics at a German medical school, a performance of certification of high-volume center for total hip and knee arthroplasties, called the EndoCert(®) Initiative, was started. This project was initiated by the German society of orthopaedic surgery (DGOOC) to secure the quality of total knee and hip arthroplasties., Objectives: The aim of this study is to evaluate effects of certification, pathwaycontrolled therapy and quality indicators on outcome in arthroplasty three years after implentation., Materials and Methods: Arthroplasties performed in this certified center for total hip and knee arthroplasties were evaluated. Outcome was evaluated after the implementation of quality indicators and clinical pathways., Results: After establishment of certification in the center for total hip and knee arthroplasties morbidity rates decreased as quality increased., Conclusion: The implementation of pathway-controlled therapy and quality indicators in a high-volume center for total joint arthroplasties shows better clinical results. Capital investment and efforts are legitimated.

Background: The primary goal of computer-assisted surgery (CAS) in total knee arthroplasty is to increase the accuracy in terms of prosthesis positioning. In theory, this would lead to longer implant survival and a reduction of malpositioning. Thus, a better clinical outcome and lower revision rates would be expected. However, the necessary technical equipment represents significant additional effort and cost factors which are not included in the current diagnosis-related groups (DRG) system., Objective: The objective of this article is a critical review of the current literature to examine whether these costs are reasonable by taking the additional benefits of the technology into account., Methods: This review is based on a selective PubMed search on CAS and navigation in primary total knee arthroplasty., Results: The current evidence base on CAS suggests that at least the primary outcome parameter, the improvement of the radiological alignment, is achieved by the technique. However, the claimed secondary effects are not yet proven. In particular, an improvement of clinical outcome and patient satisfaction has not been demonstrated so far. Furthermore, there is some evidence of increased complication rates by the use of CAS., Conclusion: Against this background and with respect to further cost-benefit analyses, the technology has to be reviewed critically. In particular, low-volume units do not seem to benefit from the use of CAS. However, the assessment of long-term effects is still pending.