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Introduction: MPFL reconstruction is widely and successfully used for treating patella instability, either as a standalone procedure or in combination. Although different techniques allow for MPFL reconstruction, the use of a free tendon graft is one of the most commonly used. The phenomenon of tunnel widening or tunnel enlargement is well described in ACL reconstruction, but so far only little effort has been put into evaluating this phenomenon after MPFL reconstruction., Materials and Methods: Patients who received an MPFL reconstruction with a free gracilis tendon graft were identified by review of patient files. Additional clinical examination and magnetic resonance imaging were performed to assess tunnel enlargement and clinical outcome., Results: Fifty-one knees of 49 patients (34 female, 17 male) with a mean follow-up of 3.0 ± 1.4 years were included in this study. Mean age at the time of surgery was 22.6 ± 8.5 years. Mean Tegner score decreased from preoperative 5.3 ± 2.0 to 4.0 ± 1.4 postoperative. Postoperative IKDC and Kujala scores were 74 ± 16 and 80 ± 15, respectively. Twenty-three patients showed a tunnel enlargement at follow-up examination. Of these 23 patients, 20 showed a tunnel that was positioned too proximal, whereas only 13 of the 28 patients showing no enlargement had a tunnel that was positioned too proximal (p = 0.0033). Interestingly, patients showing a tunnel enlargement at follow-up examination also showed significantly better Kujala (84 ± 12 vs. 75 ± 16; p = 0.03) and IKDC scores (80 ± 7 vs. 70 ± 19; p = 0.02) when compared to the non-enlarged group., Conclusion: Tunnel enlargement after MPFL reconstruction with a free gracilis tendon graft seems to be connected to mechanical overload due to a proximal malposition of the femoral tunnel. Interestingly, this did not influence clinical outcome as patients with tunnel enlargement showed better Kujala and IKDC scores.

Purpose: Femoral component malrotation in total knee arthroplasty (TKA) is clinically proven to cause dissatisfaction and impaired function. This study is an attempt to characterize the tibiofemoral kinematics following femoral malrotation in posterior stabilized (PS) TKA. It was hypothesized that internal malrotation would introduce the most pronounced changes., Methods: Six fresh-frozen cadaver specimens were mounted in a kinematic rig. Three motion patterns were applied with the native knee and following PS TKA (passive motion, open chain extension, and squatting) while infrared cameras recorded the trajectories of markers attached to femur and tibia. Three different femoral implants were tested: a conventional posterior stabilized component, and adapted components of the same implant with 5° of intrinsic external and internal rotation, respectively., Results: The implantation of the PS TKA resulted in less tibial internal rotation (squat 33-70°, p < 0.05) and the medial femoral condyle shifted posteriorly especially in deep flexion (squat 84-111°, p < 0.05). Internal component malrotation caused internal rotation and abduction of the tibia in flexion (squat 33-111°, p < 0.05), an elevated (squat 43-111°, p < 0.05) and more anterior (passive 61-126°, p < 0.05) located medial femoral condyle and a lateral femoral condyle located more posterior and inferior (squat 73-111°, p < 0.05) than in the neutrally aligned TKA. External component malrotation caused only little changes under passive motion. Under a squat there was less internal rotation and more adduction to the tibia (33-111°, p < 0.05). The medial femoral condyle was moved more posterior (squat 59-97°, p < 0.05), the lateral femoral condyle more superior (squat 54-105°, p < 0.05) than in the neutrally aligned TKA., Conclusion: The greatest differences to the native tibiofemoral kinematics were introduced by internal rotation of the femoral component. Also neutrally and externally rotated femoral components introduce kinematic changes, but to a lesser extent. With respect to the alterations introduced to kinematics internal malrotation should be avoided when performing PS TKA.

Introduction: The aim of this investigation was to analyse "total blood loss" (TBL), "blood transfusion rate" (BT) and the "amount of transfused blood units" (BU) between the different primary shoulder arthroplasty (SA) types: reverse, anatomical and stemless. Only primary SA was included. Further goal was to identify risk factors for TBL, amount of BU and BT rate., Methods: A retrospective charts analysis of patients who received primary SA for degenerative shoulder pathology in our institution between 2004 and 2016 was performed. The demographic data, co-morbidities, haemoglobin and hematocrit level, BT rate, amount of transfused BU etc. were collected. TBL was estimated. Linear regression, log-linear poisson regression and logistic regression were used to compare the outcomes TBL, amount of transfused BU and BT rate, respectively, between different prosthesis types., Results: Of 278 patients included in this study 209 received reverse, 57 anatomical and 12 stemless SA. Mean TBL was 392.7 ml in reverse, 394.6 ml in anatomical and 298.3 ml in stemless SA. The BT rate and mean amount of BU were, respectively, 14.4% and 0.32 in reverse and 8.77% and 0.23 in anatomical SA. None of the patients with stemless arthroplasty received BT. Significant risk factors for elevated TBL are operation time, higher BMI, male sex. Significant risk parameters for BT and higher amount of transfused BU are low BMI, cemented arthroplasty, coronary heart disease, ASA score > 2 and previous therapy with vitamin K antagonists., Conclusion: Although there were little differences between the blood transfusion rates in reverse vs. anatomical arthroplasty, there was no difference in total blood loss between these different prosthesis types. None of the patients with stemless arthroplasty received blood transfusion. There are various risk factors affecting total blood loss and blood transfusion rate. However, risk parameters influencing blood transfusion may be different to them affecting total blood loss.

Background: Chondrosarcoma is the second most common primary malignant bone tumor. Because of their heterogeneity, with differences in invasive and metastatic behavior, it is important to identify biological markers that will allow for a more accurate estimation of prognosis in patients with these tumors. Matrix metalloproteinases (MMP) play a crucial role in tumor progression, invasion and metastasis. The mechanism of tumor progression dependent of MMPs is complex and influences malignant transformation, angiogenesis and tumor growth at the primary and metastatic sites. The purpose of this study was to investigate immunohistochemicaly the influence of MMP-1, MMP-3, MMP-9 and MMP-13 expression on prognostic parameter in chondrosarcoma., Methods: We investigated tissue samples of 28 patients with chondrosarcoma. Immunohistochemical staining to evaluate the expression of MMP-1, MMP-3, MMP-9 and MMP-13 was performed. Subsequently, the expression level was correlated with metastatic potential, histological grading and overall survival in patients with this neoplasm., Results: In consideration of semi quantitative scoring 64% of chondrosarcoma were scored as positive for MMP-1, 46% for MMP-3, 61% for MMP-9. The specimens had shown no expression of MMP-13. High expression of MMP-9 was associated with better histological differentiation, decreased metastatic potential and favourable overall survival. No correlation was found for expression of MMP-1, MMP-3 or MMP-13., Conclusions: MMP-1, MMP-3 and MMP-9 are expressed in chondrosarcoma. Our findings suggest that the expression of MMP-9 is associated with clinical outcome parameters in chondrosarcoma.

Background: Ankle tape is widely used by athletes to prevent ankle sprain. Although there is growing evidence that ankle tape improve joint position sense, but yet it is not clear even if tape improve joint position sense after muscle fatigue, because fatigue impair joint position sense and raise the risk of ankle sprain. The aim of this study is to examine the effect of ankle tape on joint position sense after local muscle fatigue., Method: This trial is a randomized controlled trial. 34 healthy subjects participated in this trial. Subjects were randomized distributed into two groups: with tape and without tape. Active and passive absolute error and variable error mean values for two target positions of the ankle joint (15° inversions and inversion minus 5°) before and after fatigue protocol consisted of 30 consecutive maximal concentric/concentric contractions of the ankle evertors and invertors. In this trail joint position sense for all subjects was assessed using The Biodex System isokinetic dynamometer 3, this system is used also for fatigue protocol., Results: For the variable error (VE), significant mean effect was found for active joint position sense in 15° of inversion after muscle fatigue (P < 0, 05). It was a significant decrease in the work in the last third of inversion detected (P < 0, 05). There was no significant main effect found for fatigue index of eversion., Conclusion: Ankle tape can improve joint position sense at the fatigue session when joint position sense becomes worse. As a result, ankle tape may be useful to prevent ankle sprain during playing sports. We suggest athletes and individuals at risk of ankle sprain to apply taping before high-load activity., Trial Registration: The study was retrospectively registered on the ISRCTN registry with study ID ISRCTN30042335 on 12th December 2017.

Background: An increasing demand for total knee arthroplasty (TKA) has pushed innovations in the industry and created a promising new technique called patient specific instruments (PSI). Early reports had promising results such as reducing operative time, cost, and improved alignment. More recent reports are conflicting., Objective: We aimed to evaluate bleeding, operative time, complication rates, and in-hospital stay., Methods: A monocentric retrospective analysis was performed on a total of 961 patients that met inclusion criteria. Four different TKA Systems, two of which were performed using conventional instrumentation (CI) (n= 768) and two with PSI (n= 193) were trialed under the same conditions by three senior surgeons. Operative time, complications, bleeding, range of motion, and length of stay were analyzed., Results: There was no difference in operative time (p= 0.991) and length of hospital stay (p= 0.371) between PSI and CI approaches. Complication rates were lower in the PSI group. CI patients showed less non-compensated blood loss (p< 0.001) but required more transfusions (5.8% vs. 1.5%, p= 0.014)., Conclusions: There was no difference in duration of surgery, length of stay, and total blood loss when performing TKA with PSI or CI. There were fewer complications in the PSI group. It remains debatable whether these findings justify routine use of PSI in TKA.

Background: Knee and hip replacement surgery are still the mainstay therapy for osteoarthritis. In spite of the improvement of techniques and implants, anemia is a relatively common complication, with transfusion rates of up to 23% in some centers., Objective: The purpose of the study was to determine a correlation of transfusions to complications including infection since this topic is still being debated or even disputed in the literature., Methods: This is a level III, single center retrospective observational cohort study of 2760 unilateral primary knee and hip replacements. Preoperative assessment, the number of transfusions and the occurrence of complications were collected and the correlations were analyzed using analysis of variance and logistic regression., Results: Fifteen percent of all patients developed at least one complication. Transfusion rate was 9%. Risk factors for receiving a transfusion were female gender, hip replacement, American Society of Anesthesiologists' Score (ASA) > III, history of myocardial infarction, chronic cardiac disease, diabetes mellitus, chronic kidney disease, and length of surgery. The risk factors for developing a complication were: ASA score, presence of chronic renal insufficiency, and transfusion during hospital stay. Transfusion increases the risk of complications and infection rate. Complication rate with transfusion was 34.7% and without transfusion 13.2%. Infection rate without transfusion was 0.4% and with transfusion 2.82%., Conclusions: The complication rate is higher in transfused patients. The number of complications rises linearly with the number of transfusions. Infection rate is also higher after a transfusion. Efforts should be made to reduce the transfusion rate.

Purpose: Balancing mobile-bearing (MB) unicondylar knee arthroplasty (UKA) is challenging. If performed improperly, potential complications include pain, implant loosening, or progression of osteoarthritis in the preserved compartment. The purpose of this study was to document effects of improper balancing on knee kinematics and joint contact stress. It was hypothesized that over-stuffing would lead to more valgus and higher lateral contact force., Methods: Seven fresh-frozen cadaver legs were mounted in a kinematic rig that applied three motion patterns to the specimens: passive flexion-extension, open chain extension, and squatting. During testing, an infrared camera system recorded the trajectories of markers rigidly attached to femur and tibia, while a pressure sensor measured contact pressure in the lateral compartment. Prior computer tomography scans allowed identification of coordinate frames of the bones and calculations of anatomical rotations and translations. Collateral ligament strains were calculated, and quadriceps forces recorded. Following testing on the native knee, a medial MB UKA was implanted in each specimen and all motion trials were repeated. Three inlay thicknesses were tested to simulate optimal balancing as well as under- (1 mm thinner) and over-stuffing (1 mm thicker) of the medial compartment relative to the optimal thickness., Results: Under-stuffing of the medial compartment leads to kinematics closest to the native knee. Subjectively balanced and over-stuffed MB UKA knees were in more valgus. Lateral peak contact stress was higher from mid- to deep flexion following UKA in all three tested states; however, these results were not significant. Peak strain in the superficial medial collateral ligament (sMCL) was significantly higher in MB UKA, regardless of the inlay thickness mainly in mid-flexion. Inlay thickness had no significant impact on measured quadriceps force during squatting., Conclusion: The results underline the importance of optimal balancing. Over-stuffing should be avoided as it results in the largest kinematic changes relative to the native condition and induces higher strains in the sMCL. Based on the kinematic findings, it is advisable to use thinner inlays, as long as this is not compromising stability or risking inlay luxation.

Background: The recently reintroduced bicruciate retaining Total Knee Arthroplasty (BCR TKA) is an effort to reproduce kinematics closer to the native knee. However, there is no data on appropriate balancing with this implant. Balancing is crucial and challenging as medial and lateral polyethylene (PE) inlays are modular, which allows for placement of different thicknesses in the medial and lateral compartments. This study aimed at providing a detailed kinematic view on balancing BCR TKA., Methods: Seven fresh frozen cadaver legs were mounted in a kinematic rig that applied squatting under application of physiologic quadriceps and hamstring forces. Additionally, specimen laxity was assessed using Lachman tests and varus/valgus stress tests. Following testing on the native knee, a BCR TKA was implanted in each specimen and all trials were repeated. Using one millimeter increments, five inlay thicknesses were tested to simulate optimal balancing, symmetric under-, and overstuffing, valgus constellation, and varus constellation., Results: Overall, knee kinematics following BCR TKA seem to be very close to the native knee. The changes as introduced to tibiofemoral kinematics through over- or understuffing the polyethylene inserts are affecting the system only to a minor degree and generally lack statistical significance. Reproduction of the tibial varus via PE-Inlays did not lead to kinematics much closer to the native knee., Conclusions: The changes introduced to tibiofemoral kinematics by removal of the conforming meniscus and cartilage and replacement with a flat PE insert and femoral component are of more impact than different inlay sizes and their combinations for a BCR TKA., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Purpose: The recently reintroduced bicruciate-retaining Total Knee Arthroplasty (BCR TKA) is an interesting approach in the quest for close replication of knee joint biomechanics and kinematics closer to the native knee. Therefore, this study aimed at providing a detailed biomechanical view on the functional resemblance of BCR TKA to the native knee joint., Methods: Seven fresh-frozen full leg cadaver specimens (76 ± 10 year) were mounted in a 6 degrees-of-freedom kinematic rig that applied a dynamic squatting motion knee flexion. Two motion patterns were performed pre- and post-implantation of a fixed bearing BCR TKA: passive flexion-extension and squatting while an infrared camera system tracked the location of reflective markers attached to the tibia and femur. Additionally, specimen laxity was assessed using Lachman tests and varus/valgus stress tests in triplicate., Results: Overall, differences in tibiofemoral kinematics between native knee and BCR TKA were small. Some minor differences appeared under the load of a squat: less internal tibial rotation and some minor paradoxical anterior translation of the medial femoral condyle during mid-flexion. BCR TKA may slightly elevate the joint line. Knee laxity as measured by the Lachman and varus/valgus tests was not significantly influenced by BCR TKA implantation., Conclusion: As both cruciate ligaments are preserved with BCR TKA the unloaded knee closely resembles native knee kinematics including preserving the rollback mechanism. The loss of the conforming anatomy of menisci and tibial cartilage and replacement via a relatively flat polyethylene inlay may account for the loss of tibial internal rotation and the slight paradoxical AP motion of the medial femoral condyle with BCR TKA. This phenomenon reproduces findings made earlier with fixed bearing unicondylar knee arthroplasty.

Aims: We sought to establish whether an oxidised zirconium (OxZr) femoral component causes less loss of polyethylene volume than a cobalt alloy (CoCr) femoral component in total knee arthroplasty., Materials and Methods: A total of 20 retrieved tibial inserts that had articulated with OxZr components were matched with 20 inserts from CoCr articulations for patient age, body mass index, length of implantation, and revision diagnosis. Changes in dimensions of the articular surfaces were compared with those of pristine inserts using laser scanning. The differences in volume between the retrieved and pristine surfaces of the two groups were calculated and compared., Results: The loss of polyethylene volume was 122 mm 3 (standard deviation (sd) 87) in the OxZr group and 170 mm 3 (sd 96) in the CoCr group (p = 0.033). The volume loss in the OxZr group was also lower in the medial (72 mm 3 (sd 67) versus 92 mm 3 (sd 60); p = 0.096) and lateral (49 mm 3 (sd 36) versus 79 mm 3 (sd 61); p = 0.096) compartments separately, but these differences were not significant., Conclusion: Our results corroborate earlier findings from in vitro testing and visual retrieval analysis which suggest that polyethylene volume loss is lower with OxZr femoral components. Since both OxZr and CoCr are hard surfaces that would be expected to create comparable amounts of polyethylene creep, the differences in volume loss may reflect differences in the in vivo wear of these inserts. Cite this article: Bone Joint J 2017;99-B:793-8., (©2017 The British Editorial Society of Bone & Joint Surgery.)

Introduction: Different dissection studies as well as comparative studies about the anterolateral ligament of the knee (ALL) already exist and the structure's topology and properties have been shown. However, most of the studies investigating the ligament were performed in embalmed knees, which is thought to change the structural integrity of ligaments and thus the topologic and dynamic measurements. Since the biomechanical function of the ALL is not fully understood until today and a correlation with the pivot shift phenomenon is yet speculative, further studies will have to clarify its definitive importance. Its function as a limiter of internal rotation and lateral meniscal extrusion leads to the assumption of a secondary knee stabilizer., Methods: Twenty paired fresh-frozen cadaveric knees of ten donors have been dissected in a layerwise fashion. After identification of the ALL, topologic measurements were undertaken using a digital caliper., Results: The ALL could be identified as a tender, pearly structure in front of the anterolateral joint capsule in only 60% of the dissected knee joints. Only 20% of donors had a bilateral ALL while 80% had an ALL only in one side. Mean length, thickness and width as well as topographic measurements were comparable to other available studies investigating fresh-frozen cadavers., Conclusion: Anatomy and topography of the ALL seem to be highly variable, but consistent within certain borders. Prevalence has to be argued though as it strongly differs between studies. The impact of an ALL absence, even if only unilateral, needs to be investigated in clinical and imaging studies to finally clarify its importance.

Introduction: No evidence-based guidelines are available to determine the appropriate stem length, and whether or not to cement stems in revision total knee arthroplasty (TKA). Therefore, the objective of this study was to compare stresses and relative movement of cemented and uncemented stems of different lengths using a finite element analysis., Materials and Methods: A finite element model was created for a synthetic tibia. Two stem lengths (95 and 160 mm) and two types of fixation (cemented or press fit) of a hinged TKA were examined. The average compressive stress distribution in different regions of interest, as well as implant micromotions, was determined and compared during lunge and squat motor tasks., Results: Both long and short stems in revision TKA lead to high stresses, primarily in the region around the stem tip. The presence of cement reduces the stresses in the bone in every region along the stem. Short stem configurations are less affected by the presence of cement than the long stem configuration. Press-fit stems showed higher micromotions compared to cemented stems., Conclusions: Lowest stresses and micromotion were found for long cemented stems. Cementless stems showed more micromotion and increased stress levels especially at the level of the stem tip, which may explain the clinical phenomenon of stem-end pain following revision knee arthroplasty. These findings will help the surgeon with optimal individual implant choice.

Introduction: Compromised bone quality and the need for early mobilization continue to lead to implant failure in elderly patients with distal femoral fractures. The cement augmentation of screws might facilitate improving implant anchorage. The aim of this study was to analyse the impact of cement augmentation of the condylar screws on implant fixation in a human cadaveric bone model., Material and Methods: Ten pairs of osteoporotic femora (mean age: 90 years, range: 84-99 years) were used. A 2-cm gap osteotomy was created in the metaphyseal region to simulate an unstable AO/OTA 33-A3 fracture. All specimens were treated with a polyaxial locking plate. Specimens randomly assigned to the augmented group received an additional cement augmentation of the condylar screws using bone cement. A servohydraulic testing machine was used to perform incremental cyclic axial loading using a load-to-failure mode., Results: All specimens survived at least 800N of axial compressive force. The mean compressive forces leading to failure were 1620N (95% CI: 1382-1858N) in the non-augmented group and 2420N (95% CI: 2054-2786N) in the group with cement-augmented condylar screws (p=0.005). Deformation with cutting out of the condylar screws and condylar fracture were the most common reasons for failure in both groups. Whereas axial stiffness was comparable between both osteosyntheses (p=0.508), significant differences were observed for the plastic deformation of the constructs (p=0.014)., Conclusion: The results of the present study showed that the cement augmentation of the condylar screws might be a promising technique for the fixation of distal femoral fractures in elderly patients with osteoporotic bones., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Introduction: Anterior knee pain (AKP) is a frequent complication after total knee arthroplasty (TKA). Patelloplasty, defined as reshaping the patella for optimal tracking in the trochlea, has been proposed to reduce the rate of this complication in patellar retaining implants. Aim of this study was to analyze the available literature regarding the outcomes of patelloplasty and to assess its methodological quality., Materials and Methods: A comprehensive review of the English literature was performed using the keywords "total knee arthroplasty", "patelloplasty" and "patellaplasty" with no limit regarding the year of publication. All the selected articles were evaluated with the Coleman score., Results: Seven full text articles were retrieved. The initial cohort included 461 knees in the study groups and 465 in the control groups. At an average FU of 70.6 months 447 knees were reviewed in the study group and 447 in the control groups. The global rate of AKP after patelloplasty was 11.3 % which compared to 7.9 % in the patella resurfacing control group. No signs of specific patellar complications due to patelloplasty were reported. Average Coleman score was 66.9., Conclusion: Most of the literature has barely sufficient methodological quality. Patelloplasty aims at reducing patellar thickness and improve its tracking with TKA. This procedure is a safe and easy option with no reported adverse effects. In the included studies, outcome seemed to be superior in comparison with isolated osteophyte removal and denervation with a lower rate of AKP. The included studies, however, report a lower rate of AKP following TKA with patellar resurfacing. Patelloplasty may have the potential to improve the outcome of patellar retaining implants., Level of Evidence: 4, systematic review.

Purpose: Balancing unicondylar knee arthroplasty (UKA) is challenging. If not performed properly, it may lead to implant loosening or progression of osteoarthritis in the preserved compartment. This study was aimed to document the biomechanical effects of improper balancing. We hypothesised that overstuffing would lead to more valgus, higher strain in the medial collateral ligament (sMCL), and higher lateral contact force., Methods: Six fresh-frozen cadaver specimens were mounted in a kinematic rig. Three motion patterns were applied with the native knee and following medial UKA (passive motion, open-chain extension, and squatting), while infrared cameras recorded the trajectories of markers attached to femur and tibia. Three inlay thicknesses were tested (8, 9, 10 mm)., Results: Overstuffed knees were in more valgus and showed less tibial rotation and higher strains in the sMCL (p < 0.05). Lateral contact forces were higher in some specimens and lower in others. Stiffening of the medial compartment by UKA, even well balanced, already leads to a knee more in valgus with a more stressed sMCL. Overstuffing increases these effects. Knees with a tight sMCL may even see lower lateral contact force. Biomechanics were closest to the native knee with understuffing., Conclusion: The first two hypotheses were confirmed, but not the latter. This underlines the importance of optimal balancing. Overstuffing should certainly be avoided. Although kinematics is only slightly affected, contact forces and ligament strains are considerably changed and this might be of more clinical importance. It is advisable to use thinner inlays, if stability is not compromised.

Purpose: The preservation of meniscal structure and function after segmental meniscal loss is of crucial importance to prevent early development of osteoarthritis. Implantation of artificial meniscal implants has been reported as a feasible treatment option. The purpose of this study was to assess the clinical and magnetic resonance imaging (MRI) results 4 years after implantation of a polyurethane scaffold for chronic segmental medial meniscus deficiency following partial medial meniscectomy., Methods: Eighteen patients received arthroscopic implantation of an Actifit(®) polyurethane meniscal implant (Orteq Sports Medicine, London, UK) for deficiency of the medial meniscus. Patients were followed at 6, 12, 24, and 48 months. Clinical outcome was assessed using established patient-reported outcome scores (KOOS, KSS, UCLA Activity Scale, VAS for pain). Radiological outcome was quantified by MRI scans after 6, 12, 24, and 48 months evaluating scaffold morphology, tissue integration, and status of the articular cartilage as well as signs of inflammation., Results: Median patient age was 32.5 years (range 17-49 years) with a median meniscal defect size of 44.5 mm (range 35-62 mm). Continuing improvement of the VAS and KSS Knee and Function Scores could be observed after 48 months compared to baseline, whereas improvement of the activity level according to UCLA continued only up to 24 months and decreased from there on. The KOOS Score showed significant improvement in all dimensions. MRI scans showed reappearance of bone bruises in two patients with scaffold extrusion. No significant changes in the articular cartilage could be perceived., Conclusion: Arthroscopic treatment for patients with chronic segmental meniscal loss using a polyurethane meniscal implant can achieve sustainable midterm results regarding pain reduction and knee function., Level of Evidence: IV.

The anterolateral ligament of the knee (ALL) has caused a lot of rumors in orthopaedics these days. The structure that was first described by Segond back in 1879 has experienced a long history of anatomic descriptions and speculations until its rediscovery by Claes in 2013. Its biomechanical properties and function have been examined recently, but are not yet fully understood. While the structure seems to act as a limiter of internal rotation and lateral meniscal extrusion its possible proprioceptive effect remains questionable. Its contribution to the pivot shift phenomenon has been uncovered in parts, therefore it has been recognized that a concomitant anterolateral stabilization together with ACL reconstruction may aid in prevention of postoperative instability after severe ligamentous knee damages. However, there are a lot of different methods to perform this procedure and the clinical outcome has yet to be examined. This concise review will give an overview on the present literature to outline the long history of the ALL under its different names, its anatomic variances and topography as well as on histologic examinations, imaging modalities, arthroscopic aspects and methods for a possible anterolateral stabilization of the knee joint.

Introduction: Progression of osteoarthritis in the unreplaced compartment following unicondylar knee arthroplasty (UKA) may be hastened if kinematics is disturbed following UKA implantation. The purpose of this study was to analyze tibiofemoral kinematics of the balanced and overstuffed UKA in comparison with the native knee during passive flexion since this is a common clinical assessment., Methods: Ten cadaveric knees were mounted to robotic manipulator and underwent passive flexion from 0 to 90°. The kinematic pathway was recorded in the native knee and in the balanced, fixed bearing UKA. The medial UKA was implanted using a measured resection technique. Additionally, a one millimeter thicker tibial insert was installed to simulate the effects of overstuffing. Tibial kinematics in relation to the femur was recorded., Results: Following UKA the tibia was externally rotated, and in valgus relative to the native knee near extension. In flexion, installing the UKA caused the knee to be translated medially and anteriorly. The tibia was translated distally through the entire range of flexion after UKA. Compared to the balanced UKA, overstuffing further increased valgus at full extension and distal translation of the tibia from full extension to 45° flexion., Conclusions: UKA implantation altered tibiofemoral kinematics in all planes. Differences were small; nevertheless, they may affect tibiofemoral loading patterns., Clinical Relevance: Alterations in tibiofemoral kinematics following UKA might have implications for prosthesis failure and progression of osteoarthritis in the remaining compartment. Overstuffing should be avoided as it further increased valgus and did not improve the remaining kinematics., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Purpose: Although there are various new scaffold-based techniques for cartilage regeneration it remains unclear up to which defect size they can be used. The present study reports of a cell-free collagen type I gel matrix for the treatment of large cartilage defects of the knee after a two-year follow-up., Methods: Twenty-eight patients with a mean cartilage defect size of 3.71 ± 1.93 cm² were treated with a cell-free collagen type I gel matrix (CaReS-1S®, Arthro Kinetics AG, Krems/Donau, Austria) via a mini-arthrotomy. Clinical outcome was assessed preoperatively and six weeks as well as six, 12 and 24 months after surgery using various clinical outcome scores (IKDC, Tegner, KOOS, VAS). Cartilage regeneration was evaluated via MRI using the MOCART score., Results: Seventeen male and 11 female patients with a mean age of 34.6 years were included in this study. Significant pain reduction (VAS) could be noted after six weeks already. Patient activity (IKDC, Tegner) could be significantly improved from 12 months on and nearly reached reported pre-operative values. All subject categories of the KOOS except for symptom (swelling) showed significant improvements throughout the study. Constant significant improvements of the mean MOCART score were observed from 12 months on. MR images did not yield any signs of infection or synovitis. After 24 months a complete defect filling could be noted in 24 out of 28 cases with a mainly smooth surface, complete integration of the border zone and homogenous structure of the repaired tissue., Conclusion: Cell-free collagen type I matrices appear to be a safe and suitable treatment option even for large cartilage defects of the knee. Results of this study were comparable to the better-established findings for small cartilage defects. Mid- and long-term results will be needed to see if clinical and MR-tomographic outcome can be maintained beyond 24 months.

Purpose: Correct rotational alignment of components is crucial for the success of total knee arthroplasty (TKA). Defining landmarks on the tibia that allow for reproducible measurement of component rotation seems to be more challenging than on the femoral side. This study compares the reproducibility of three different measurement techniques., Scope: A magnetic resonance imaging (MRI) analysis of 55 patients following TKA was conducted. The rotation of the tibial components was determined using three different reference lines: a tangent to the posterior tibial margin, the tibial epicondylar axis, and the tibial tubercle. Data were analyzed for intra- and inter-observer reliability using intra-class correlation coefficients (ICCs), and a variance comparison between measurement techniques via F-test., Results: Highest reliability and lowest variances for measurement of tibial component rotation were achieved by relation to the tibial epicondylar axis and posterior tibial margin. The tibial tubercle proved to be less reliable (ICC 0.632 (interobserver) and 0.526 (intraobserver)), and variances were significantly higher in comparison with the other two techniques., Conclusion: Based on the presented MRI data, measurements of the tibial component rotation are done best using the posterior tibial margin and the tibial epicondylar axis. The tibial tubercle measurement proved to be less reliable for this purpose. We suggest that all three reference lines will be used for assessment of a painful knee following TKA to allow for informed decision making and for choice of best treatment options for the patient., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: The ideal treatment for juvenile osteochondritis dissecans of the talus (ODT) is still unclear. To determine predictors of failure of conservative treatment, children admitted for ODT were retrospectively analyzed., Methods: Patient files were analyzed to search for children treated for an ODT between 2000 and 2011. X-rays and MRI at baseline were evaluated for grading of lesions and the patient history was obtained. Final follow-up evaluation was performed via questionnaire and complementary telephone interview. Outcome was measured using the AOFAS and the Olerud/Molander scores. Conservative treatment consisted of out of sports and modification of activity under full weight-bearing. In case of persisting pain, full load removal on crutches was initiated. For further analysis, two groups were formed: (1) successful conservative treatment; (2) converted to surgical therapy. A logistic regression was used to determine potential predictors of conservative treatment failure., Results: Seventy-seven lesions in 67 children with a mean age of 11.4 years (range 4-15 years) at the time of diagnosis were identified. Every patient received conservative treatment as a first-line treatment after diagnosis of ODT except for one single patient with a grade IV lesion at time of diagnosis who received operative treatment directly after diagnosis. Sixty-one percent of the lesions failed conservative treatment. A higher age as well as a grade III lesion at time of diagnosis was predictive for failure of the conservative treatment (p = 0.03 and p = 0.02, respectively). Regarding the functional outcome, a higher grade lesion in general was predictive for an inferior outcome as measured by clinical score., Conclusion: Grade III ODT especially in older children leads significantly more often to treatment failure when treated non-surgically. No other predictors for treatment failure could be identified., Level of Evidence: Level III (retrospective comparative study).

Polyethylene wear in total knee arthroplasty is a still unsolved problem resulting in osteolysis and long-term failure of knee joint replacement. To address the problem of polyethylene wear, research aimed for an optimal implant design and for an optimal combination of bearing surfaces. Oxidized zirconium was introduced to minimize surface wear and thus potentially increase long-term implant survival. This review comprises the current literature related to in vitro and in vivo studies evaluating performance of oxidized zirconium total knee arthroplasty and results from retrieval analyses., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Introduction: Limb alignment after unicondylar knee arthroplasty (UKA) has a significant impact on outcomes. The literature lacks lateral UKA alignment studies, making our understanding of this issue based on medial UKA., Methods: We evaluated limb alignment in 241 patients who underwent medial (229 knees) or lateral (37 knees) UKA. Alignment was measured pre and postoperatively in radiographs and intra-operatively using a navigation system. We compared the percentage of over-correction and the difference between post-operative alignment and navigation measurement., Results: Percentage of overcorrection was significantly higher in the lateral UKAs (11%) compared to the medial UKAs (4%). In medial UKAs, the mean difference between the intraoperative alignment and the post-operative was 1.33°. This was significantly lower than the mean 1.86° difference in the lateral UKAs., Conclusions: Our data demonstrated an increased risk of "overcorrection," and greater difficulty in predicting postoperative alignment using computer navigation, when performing lateral UKAs compared to medial UKAs., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Introduction: Function and kinematics following unicondylar knee arthroplasty (UKA) have been reported to be close to the native knee. Gait, stair climbing and activities of daily living expose the knee joint to a combination of varus and valgus moments. Replacement of the medial compartment via UKA is likely to change the physiologic knee stability and its ability to respond to varus and valgus moments. It was hypothesized that UKA implantation would stiffen the knee and decrease range of motion in the frontal plane., Materials and Methods: Six fresh frozen cadaver knees were prepared and mounted in a six-degrees-of-freedom robot. An axial load of 200 N was applied with the knee in 15°, 45° and 90° of flexion. Varus and valgus moments were added, respectively, before and after implantation of medial UKA. Tests were than redone with a thicker polyethylene inlay to simulate overstuffing of the medial compartment. Range of motion in the frontal plane and the tibial response to moments were recorded via the industrial robot., Results: The range of motion in the frontal plane was decreased with both, balanced and overstuffed UKA and shifted towards valgus. When exposed to valgus moments, knees following UKA were stiffer in comparison with the native knee. The effect was even more pronounced with medial overstuffing., Conclusion: In UKA, the compressive anatomy is replaced by much stiffer components. This lack of medial compression and relative overstuffing leads to a tighter medial collateral ligament. This drives the trend towards a stiffer joint as documented by a decrease in frontal plane range of motion. Overstuffing should strictly be avoided when performing UKA.

Introduction: Posterior-stabilized (PS) and cruciate-retaining (CR) total knee arthroplasties (TKA) are both successfully used for treatment of end-stage osteoarthritis. The choice of constraint depends on knee deformity and stability as well as most importantly surgeon preference. The aim of this study was to compare the amount of blood loss and required transfusions following TKA with the two different designs., Materials and Methods: In a retrospective approach, 473 patients undergoing TKA were included (240 CR and 233 PS from a single manufacturer). Demographics at base line were comparable between both groups. Blood loss [red blood cell (RBC) loss] was calculated after documentation of pre- and postoperative hematocrit levels at discharge. Transfusion requirements were recorded. Statistical analysis was done using Mann-Whitney U test., Results: The calculated blood loss (RBC loss) at discharge was 548 ± 216 ml in the PS group compared with 502 ± 186 ml in the CR group (p = 0.032). There were no differences in the transfusion requirements between both groups (PS 0.41 vs. CR 0.37, p = 0.39)., Discussion: The blood loss was significantly higher in the PS group. This may be due to the box preparation that exposes more cancellous femoral bone, which may add to postoperative bleeding. The differences remain, however, small, as they did not lead to a significantly higher transfusion rate with PS TKA.

Introduction: Patient-specific instrumentation (PSI) was introduced in an attempt to reduce positional outliers of components in total knee arthroplasty (TKA). It was hypothesized that PSI could help with the positioning of tibial components in optimal rotational alignment., Methods: A magnetic resonance imaging (MRI) analysis of 58 patients following TKA was conducted. Of these, 30 operations were performed using PSI and 28 using conventional instrumentation. The rotation of the tibial components was determined in MRI using three different reference lines: a tangent to the dorsal tibial condyles, the tibial epicondylar line, and the tibial tubercle. Deviations >9° were considered outliers. Also internal rotation >1° was considered an outlier. Data were analyzed statistically for positional outliers using the Chi-squared test., Results: There was excellent inter- and intraobserver reliability with low standard deviations for the determination of tibial component rotation using the tangent to the dorsal condyles and the tibial epicondylar line as reference. Using the dorsal tangent as reference, there were eight components in excessive external rotation (28.6 %) and one component being in relative internal rotation (5.4°) in the conventional group, while there were two components in excessive external rotation in the PSI group (6.7 %). Using the tibial epicondyles as reference, there were seven components in excessive external rotation (21.4 %) and one component being in relative internal rotation (4.4°) in the conventional group; while there were two components in excessive external rotation in the PSI group (6.7 %). These differences were statistically significant (p < 0.05). Measurements based on the tibial tubercle showed poor reproducibility in terms of intra- and interobserver reliability and was of little use in the context of the research question., Discussion and Conclusion: In this setup, PSI was effective in significantly reducing outliers of optimal rotational tibial component alignment during TKA. Anatomy of the proximal tibia does not deliver clear landmarks that are prominent and consistent. This makes both, MRI analysis as well as cutting jig production and intraoperative placement a challenge.

Background: Loosening is one of the major long-term failure modes in unicondylar knee arthroplasty (UKA). The aim of the study is to describe and characterize implant-bone interface of femoral and tibial components after UKA by means of magnet resonance imaging (MRI)., Material and Methods: MRI tailored to reduce metallic artefact of the knee after medial UKA was performed in 10 patients as a pilot study. The component-bone interface at femoral and tibial components was evaluated by two independent investigators. They gave degree of confidence to their evaluation of each parameter on a five-point scale. Inter-observer reliability was determined., Results: Artefacts provoked by the implants were rare. Inter-observer reliability and confidence were excellent for the femoral interface. They were lower at the tibial interface but results were still satisfactory., Conclusions: Tailored MRI allows reproducible analysis of the component-bone interface after UKA. It is helpful in assessment of suspected loosening after UKA.

Background: Component malposition is one of the major reasons for early failure of unicompartmental knee arthroplasty (UKA)., Questions/purposes: It was investigated how reproducibly patient-specific instrumentation (PSI) achieved preoperatively planned placement of the tibial component in UKA specifically assessing coronal alignment, slope and flexion of the components and axial rotation., Patients and Methods: Based on computer tomography models of ten cadaver legs, PSI jigs were generated to guide cuts perpendicular to the tibial axis in the coronal and sagittal planes and in neutral axial rotation. Deviation ≥3° from the designed orientation in a postoperative CT was defined as outside the range of acceptable alignment., Results: Mean coronal alignment was 0.4 ± 3.2° varus with two outliers. Mean slope was 2.8 ± 3.9° with six components in excessive flexion. It was noted that the implants were put in a mean of 1.7 ± 8.0° of external rotation with seven outliers., Conclusions: PSI helped achieve the planned coronal orientation of the component. The guides were less accurate in setting optimal tray rotation and slope.

Evidence for the efficacy of extracorporeal shock wave therapy (ESWT) in supraspinatus tendinopathy without calcification is sparse, and therefore this treatment option is often controversial. Patients of a randomized placebo-controlled study to analyze the effects of ESWT on function and pain were revisited 10 years after the initial consultation. The former verum group received 6000 impulses (energy flux density, 0.11 mJ/mm²) in three sessions after local anesthesia between 1999 and 2000. The placebo group had 6000 impulses of a sham ESWT after local anesthesia in the same period. Re-evaluation of the patients included a relative Constant score as well as pain measurements (visual analogue scale) during activity and at rest. No significant changes (p>0.05) in relative Constant scores, pain at rest, or pain during activity could be found after a 10-year follow-up between the placebo and verum groups after ESWT. The treatment of non-calcific supraspinatus tendinopathy with ESWT does not seem to have an effect on function or pain improvement in the long run. The results of the present study cannot advise the use of ESWT in cases of non-calcific supraspinatus tendinopathy.

Purpose: It is assumed that unicondylar knee arthroplasty (UKA) features kinematics close to the natural knee. Clinical studies have also shown functional benefits for UKA. There is to date only little biomechanical data to support or explain these findings. The purpose of this study was to investigate whether UKA is able to preserve natural knee kinematics or not., Methods: Six fresh frozen full leg cadaver specimens were prepared to be mounted in a kinematic rig with six degrees of freedom for the knee joint. Three motion patterns were applied before and after medial UKA: passive flexion-extension, open chain extension, and squatting. During the loaded motions, quadriceps and hamstrings muscle forces were applied. Infrared cameras continuously recorded the trajectories of marker frames rigidly attached to femur, tibia, and patella. Prior computer tomography allowed identification of coordinate frames of the bones and calculations of anatomical rotations and translations., Results: Native kinematics was reproduced after UKA in all the specimens. In the unloaded knee and during open chain extension, femoral rollback patterns after UKA were very close to those in the native knee. During squatting, the medial femoral condyle after UKA tended to be more posterior and superior with flexion and there was less tibial internal rotation. The tibia was found to be more in valgus after UKA during all motion patterns., Conclusion: As ligaments, lateral compartment and patellofemoral anatomy are preserved with UKA; the unloaded knee closely resembles native kinematics. The slight kinematic changes that were found under load are probably due to loss of the conforming medial meniscus and to the mismatch in geometry and stiffness introduced by UKA. These patterns resemble those found in knees with significant loss of function of the medial meniscus.

Background: Polyethylene (PE) wear is a major contributor to implant loosening following total knee arthroplasty (TKA). Advanced bearings are therefore required in TKA to reduce or eliminate wear-related loosening. A recently introduced bearing that combines oxidized zirconium with highly cross-linked PE has been shown to drastically reduce wear in in vitro settings, due to its improved tribological characteristics in both tibial and femoral components. However, there are no data on its cost-effectiveness., Data and Methods: A Markov model was developed to assess the cost-effectiveness of this low-wear bearing from a German societal perspective. The model population was derived from a registry of 75,000 patients requiring TKA. The model allocated patients to receive either a low-wear or standard articulation, and followed them until death. Revisions and re-revision were included. Input values were derived from registry databases or from published reports in the literature. Threshold analysis and probabilistic sensitivity analysis were conducted to estimate model robustness., Results: The low-wear articulation prevented 24 (2.4 percent) revisions and 8 (0.8 percent) re-revisions. The total incremental cost-effectiveness ratio (ICER) of the low-wear articulation was EUR 16,474 per quality-adjusted life-year (QALY). For patients aged less than 55 years, an ICER of EUR 653 per QALY was observed. For patients aged over 75 years, this value was EUR 83,300. Threshold and probabilistic sensitivity analysis indicated that these findings were reasonably robust., Conclusion: Low-wear articulations may be considered cost-effective, although the cost effectiveness is age-dependent, with the cost per QALY being significantly lower for younger people than for older people.

Background: Squeaking after ceramic-on-ceramic total hip arthroplasty is a relatively uncommon phenomenon. It usually does not require treatment in the absence of pain, mechanical symptoms, and/or relentless squeaking. The purpose of this investigation was to report on four patients who presented with hip pain and squeaking due to fractured ceramic liners after ceramic-on-ceramic total hip arthroplasty., Methods: Four patients with painful squeaking after ceramic-on-ceramic total hip arthroplasty were seen at our institution. One patient had a revision for suspected loosening and excessive anteversion of the cup noted on radiographs and magnetic resonance imaging (MRI). The remaining three patients had a revision for audible squeaking with progressive pain., Results: Intraoperatively, the ceramic liners of all four patients were fractured., Conclusions: Squeaking after ceramic-on-ceramic total hip arthroplasty rarely is a functional issue. However, painful squeaking without notable trauma may indicate fracture of the ceramic liner. Painful squeaking is difficult to evaluate by conventional imaging. When painful squeaking occurs, exploration via surgical revision is recommended in selected patients, as ceramic liner fractures may go unnoticed on radiographs and/or MRI and thus their actual prevalence may be higher than estimated.

Background: Oxidized zirconium (OxZr) was introduced as an alternative bearing for femoral components in total knee arthroplasty (TKA) in an attempt to reduce wear compared with conventional cobalt-chromium (CoCr) alloys., Questions/purposes: The aim of this study was to compare matched pairs of retrieved OxZr and CoCr components using surface profilometry; specifically, we sought to compare the surface roughness of (1) retrieved OxZr TKA components with retrieved CoCr components; (2) the medial versus the lateral femoral condyles of retrieved components; and (3) unimplanted OxZr TKA components with unimplanted CoCr components., Methods: Ten retrieved posterior-stabilized Genesis II TKA with OxZr femoral components were identified and matched to retrieved CoCr femoral components by duration of implantation, patient age, and body mass index. A noncontact white light interferometer was used to evaluate surface roughness. One pristine, unimplanted component of each design was analyzed as a control., Results: The retrieved components showed significantly (p < 0.0001) lower roughness for the OxZr components than the CoCr components. CoCr retrievals showed a significantly greater average surface roughness on the medial condyle. No difference was found between the condyles of the OxZr components. The pristine CoCr implant had a significantly lower surface roughness than the pristine OxZr component., Conclusions: CoCr roughens significantly more in situ compared with OxZr components., Clinical Relevance: Bearing surfaces are typically damaged in vivo. The extent of damage is variable between patients and implants; however, rougher surfaces should be associated with more wear. Whether the differences observed in our study prove meaningful requires long-term clinical data.

Purpose: Modular bicompartmental knee arthroplasty (BKA) for treatment of medio-patellofemoral osteoarthritis (OA) should allow for close to normal kinematics in comparison with unicondylar knee arthroplasty (UKA) and the native knee. There is so far no data to support this., Scope: Six fresh frozen full leg cadaver specimens were prepared and mounted in a kinematic rig with six degrees of freedom for the knee joint. Three motion patterns were applied with the native knee and after sequential implantation of medial UKA and patellofemoral joint replacement (PFJ): passive flexion-extension, open chain extension, and squatting. During the loaded motions, quadriceps and hamstrings muscle forces were applied. Infrared cameras continuously recorded the trajectories of marker frames rigidly attached to femur, tibia and patella. Prior computer tomography allowed identification of coordinate frames of the bones. Strains in the collateral ligaments were calculated from insertion site distances., Results: UKA led to a less adducted and internally rotated tibia and a more strained medial collateral ligament (MCL). Addition of a patellofemoral replacement led to a more posterior position of both femoral condyles, a more dorsally located tibiofemoral contact point and higher MCL strain with squatting., Conclusion: In comparison to UKA modular BKA leads to a more dorsal tibial contact point, a medial femoral condyle being located more posteriorly, and more MCL strain. Mainly the changes to the trochlear anatomy as introduced by PFJ may account for these differences., (© 2014 Elsevier B.V. All rights reserved.)

Background: Total knee arthroplasty (TKA) for juvenile idiopathic arthritis is rare but is nonetheless indicated for many patients with this disease. Few reports exist on the results of TKA in patients with juvenile idiopathic arthritis., Questions/purposes: It was sought to determine (1) survivorship and (2) functional outcomes of TKAs in patients with juvenile idiopathic arthritis., Methods: Results were combined from patients treated by experienced surgeons at five hospitals between 1979 and 2011. Two hundred nineteen patients (349 TKAs) were identified and contacted to survey their outcomes at a minimum followup of 2 years (mean, 12 ± 8 years; range, 2-33 years). The average age at surgery was 28.9 ± 9.7 years (range, 11-58 years). Data on revision surgery and ability to perform daily activities were collected., Results: The 10-year survivorship was 95%, decreasing to 82% by 20 years. At latest followup, 31 of 349 TKAs (8.9%) had been revised for either polyethylene failure or loosening (18 TKAs), infection (four), stiffness (three), periprosthetic fractures (two), bilateral amputation for vascular reasons (two), patellar resurfacing (one), and instability (one). Walking tolerance was unlimited in 49%, five to 10 blocks in 23%, and less than five blocks in 28%. Eleven percent could not manage stairs, and another 59% depended on railings. A cane was used by 12% and crutches by 7%; 12% were wheelchair-dependent., Conclusions: TKA survivorship in patients with juvenile idiopathic arthritis was inferior to that typically seen in younger patients with osteoarthritis or even rheumatoid arthritis confirming results of earlier studies with smaller patient numbers. This is especially disconcerting because younger patients require better durability of their TKAs.

Background: Bleeding remains an ongoing concern after total knee arthroplasty (TKA). Intraarticular application of human fibrinogen with a topical thrombin has been described to stop diffuse bleeding in knee arthroplasty., Questions/purposes: It was hypothesized that the use of human fibrinogen as a topical agent would result in a reduction of bleeding and transfusions required after TKA; secondary end points included comparison of early clinical results including pain scores and range of motion (ROM) at 6 weeks and complications after surgery., Methods: Two hundred patients undergoing TKA were randomized into a double-blind clinical trial to receive either intraarticular fibrinogen 2 minutes before tourniquet release or no such treatment. Postoperative hemoglobin and hematocrit levels, drain output, and transfusion requirements were recorded and blood loss was calculated. Clinical outcomes and adverse events were tracked prospectively. Descriptive analysis was performed using a two-sample t-test., Results: There were no differences in calculated blood loss between the fibrinogen and the control groups; the mean postoperative drain output was 780 ± 378 mL in the fibrinogen group compared with 673 ± 301 mL in the control group (p = 0.029), but the hemoglobin drop at Day 2 was 3.47 ± 1.53 g/L in the fibrinogen group and 3.84 ± 1.24 g/Ll in the control group (p = 0.051). There were no differences in in transfusions, early ROM, visual analog pain scores, or complications between the groups., Conclusions: The use of fibrinogen in TKA did not lead to a significant reduction of blood loss or transfusions in primary TKA for osteoarthritis. Given the lack of benefits and the costs this procedure adds to TKA, its routine use cannot be justified during primary TKA for osteoarthritis.

Background: Patient-specific instrumentation (PSI) was introduced in an attempt to reduce positional outliers of components in total knee arthroplasty (TKA). It was hypothesized that PSI could help with the positioning of femoral components in optimal rotational alignment., Methods: A magnetic resonance imaging (MRI) analysis of 94 patients following TKA was conducted. Of these, 46 operations were performed using PSI and 48 using conventional instrumentation. The rotation of the femoral components was determined in the MRI and deviations>3° were considered outliers. Data were analyzed for positional outliers, observer reliability, and a variance comparison between implant groups., Results: There was excellent inter- and intraobserver reliability with low standard deviations for the determination of femoral component rotation. There were significantly more outliers in the conventional (22.9%) group than in the PSI group (2.2%, p=0.003)., Conclusion: In this setup, PSI was effective in significantly reducing outliers of optimal rotational femoral component alignment during TKA., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Introduction: This pilot study used magnet resonance imaging (MRI) to analyse the rotation of medial unicondylar knee arthroplasty (UKA) components and assessed how accurately the results could be reproduced., Materials and Methods: Knee MRI using a special protocol to reduce metal artefact was performed in ten patients who had undergone medial UKA. Two independent investigators measured the rotation angle of femoral (zirconium) and tibial (cemented full-poly or cemented modular metal-backed) components applying different reference lines for the latter. Statistical analysis comprised tests for reliability, variance between measurement techniques, standard deviations and limits of agreement., Results: For all methods tested, there was sufficient inter- and intra-observer reliability. Lowest variances were, however, found for the femoral epicondyles, for both femoral and tibial components. A tangent to the dorsal epicondyles of the tibia also gave reproducible results with low variances for the tibial component., Discussion: Almost all applied measurement techniques were reproducible by statistical definition, although some of them resulted in substantial differences between both, observations and observers. A variance test helps to distinguish better between clinically useful and less accurate references., Conclusion: MRI allows good reproducible rotation analysis via the femoral epicondyles for both femoral and tibial UKA implants. For the tibia, the tibial tuberosity, the eminentia and the tibial epicondyles in particular were shown to be less reliable. The dorsal epicondyles seem to be most suitable for the tibial component.

Background: In an earlier paper, it was shown that tailored magnetic resonance imaging (MRI) allows for reproducible analysis of the preserved knee joint structures after patellofemoral replacement (PFR)., Purposes: This pilot study investigates to what degree MRI could produce reliable assessment of the implant-bone interface of femoral and patellar components and rotational alignment following PFR., Methods: MRI tailored for reduction of metallic artefacts was performed in seven patients who had undergone PFR. Two independent investigators evaluated the implant-bone interface at femoral and patellar components and the rotational alignment of the femoral component. They also assessed their degree of confidence in evaluation using a five-point scale. The inter-observer reliability was determined., Results: Implant-induced MRI artefact was barely observed and there was no interference with component-bone interface evaluation. There was excellent inter-observer reliability, inter-observer agreement, and confidence for the implant-bone interface at femoral and patellar components and for rotational alignment. The applied score for the interface was found to be reliable., Conclusion: Tailored MRI allows reproducible analysis of the implant-bone interface and of rotational alignment of the femoral component in patients who have had PFR. It might prove helpful in the assessment of painful PFR.

The aim of the study was to evaluate the mid-term clinical results and survivorship of a rotating-hinge knee prosthesis (LINK® Endo-Model) in difficult primary and complex revision situations. Results after primary implantation were compared with those of revision procedures. Forty-nine prostheses in 45 patients were reviewed clinically during follow up. Twenty-one of these were implanted in primary and 28 in revision situations. Outcome was evaluated using commonly used scores (Knee Society, UCLA Activity, Lequesne) and a visual analog scale after a mean follow up of 56±37 months for 49 prostheses. Implant survival was analyzed using the Kaplan-Meier method. There were no significant differences in clinical examination and evaluation scores between the two groups (P>0.05). Survival rates at final follow up were 95% after primary implantation and 76% in revision procedures. The risk of prosthesis loss (odds ratio 5.7) was significantly higher after revision procedures (P=0.004). These data suggest that rotating-hinge knee prostheses provided good clinical and functional results in selected cases of advanced primary gonarthrosis associated with severe bone loss, ligamentous instability or comminuted fractures. They also provide good results in revision situations. However, the failure rate was significantly higher in cases of revision surgery.

Purpose: The aim of this study was to assess the reproducibility of using magnetic resonance imaging (MRI) to analyze the preserved anatomic knee compartments following unicondylar knee arthroplasty (UKA) with zirconium femoral components. It was hypothesized that evaluation of the cartilage, ligaments, meniscus, and tendons would result in a high rate of inter-observer reliability., Scope: Ten patients underwent MRI of the knee tailored to reduce metallic artifact following medial UKA with zirconium femoral implants. Cartilage, external meniscus, collateral and cruciate ligaments, the quadriceps and patellar tendons, and the presence of joint effusion were evaluated by two independent investigators. The reviewers provided degrees of confidence with their evaluation of each parameter through the use of a five-point scale. Inter-observer agreement was calculated and inter-observer reliability was determined by use of Cohen's Kappa. Artifacts originating from the implants were rarely observed. There was excellent inter-observer reliability (i.e., high Cohen's Kappa) for all assessed structures, and a high level of observer confidence for the evaluation of the cartilage, meniscus, tendons, ligaments, and joint effusion., Conclusion: In this study tailored MRI allows for reproducible analysis of the preserved knee joint compartment after UKA for zirconium implants. This technique might prove helpful in the assessment of painful knee joints after UKA with other metallic materials as new MRI software programs, which suppress metal artifacts, are developed., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Background: Unicompartmental knee arthroplasty (UKA) is known to be a viable procedure allowing for preservation of the intact compartments and delivering excellent function at long-term follow-up. The primary purpose of this single-surgeon study was to analyse the survivorship of a fixed bearing UKA in patients younger than 60 years., Methods: From all UKAs implanted between 1993 and 2005 at the senior authors' centre, 223 patients <60 years at operation with a minimum follow-up of 5 years were identified including all-poly and metal-backed tibiae. They were evaluated applying the Knee Society Score (KSS) at latest follow-up. Survivorship was calculated using Kaplan-Meier analysis, which considered the following variables: gender, type of tibial implant, medial vs. lateral UKA, and age., Results: Average age at index operation was mean 53.7 (SD 5.8, range 30-60) years at a mean follow-up of 10.8 (SD 3.5, range 5-17) years. From the KSS, the knee score was 94.3 (SD 7.8) and the function score was 94.9 (SD 6.8). At latest follow-up, the implant survival rate was 94.3%. Survivorship for the entire cohort was 93.5% at 10 years (medial UKA 94.1% vs. lateral 91.8%), and 86.3% at 15 years (85.1% medial vs. 91.7% lateral), Conclusion: In conclusion, excellent survival and function outcomes were noted in this subgroup of patients younger than 60 years. Revision rates were comparable to those studies in which UKA was performed on an elderly patient population. UKA can successfully be performed in patients younger than 60 years with appropriate patient selection., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The use of intramedullary alignment guides for performing the distal femoral resection in total knee arthroplasty (TKA) have not been shown to be highly accurate. Forty-eight knees underwent a TKA using a portable, accelerometer-based surgical navigation system for performing the distal femoral resection (KneeAlign 2 system; OrthAlign, Inc, Aliso Viejo, Calif). Of the femoral components, 95.8% were placed within 90° ± 2° to the femoral mechanical axis in the coronal plane, and 93.8% of the TKAs had an overall lower extremity alignment within 3° of neutral to the mechanical axis, based on postoperative, standing, hip-to-ankle radiographs. The KneeAlign 2 is highly accurate in positioning the femoral component in TKA, and accelerometer-based navigation is able to reliably determine the hip center of rotation and femoral mechanical axis., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Purpose: The aim of this study was to analyze rotation of total knee (TKA) implant components using magnetic resonance imaging (MRI) and to assess the reproducibility of results. It was hypothesized that rotation of both femoral and tibial implants would be reliably reproduced., Methods: A retrospective analysis of 55 MRI studies in subjects with painful TKA implants was conducted. There were 27 zirconium and 28 cobalt/chrome/molybdenum alloy (CoCrMo) femoral components in the group. The rotation angle of femoral and tibial components was measured and determined. Statistical analysis included tests for reliability, variance between implant groups, standard deviations and confidence intervals., Results: There was a sufficient inter- and intra-observer reliability determined for rotation in all implants. The inter-observer reliability was notably higher in the zirconium femur group with significant less variance and lower standard deviations than the CoCrMo femoral component comparison group. Standard deviations for femoral rotational analysis were within a clinically acceptable range. The standard deviations were considerably higher in the tibial component rotational analysis., Conclusion: MRI analysis of the rotation of femoral implants after TKA allows good reproducibility, especially with review of zirconium implants. There is less reproducibility for tibial components related to the applied geometric method to quantify rotation and not to the MRI technique., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Purpose: Meniscal loss is associated with an increased risk of developing osteoarthritis. Tissue engineering solutions, which include the development of novel material scaffolds, are being utilised to aid the regeneration of meniscal tissue. The purpose of this study was to monitor the safety profile and the short-term efficacy of a novel polyurethane meniscal scaffold in the treatment of patients with painful knees following partial medial meniscectomy., Methods: Ten consecutive patients with segmental tissue loss from the medial meniscus were treated with the arthroscopic implantation of an Actifit(®) (Orteq Sports Medicine) polyurethane meniscal scaffold. Patients were followed up at 2 and 6 weeks, then again at 6 and 12 months. Primary outcome measures included reporting of complications and patient-reported outcome scores (KOOS, KSS, UCLA Activity scale, VAS pain). Secondary outcome was MRI assessment at 6 and 12 months looking at scaffold morphology, integration and associated joint injury/inflammation., Results: Eight male and 2 female patients were included in the study with a mean age of 29 (range 18-45). No complications were reported. All patients were happy with their surgery. At 6 months, a statistically significant improvement (P < 0.05) in all PROMS except the UCLA activity scale and VAS pain scale were noted. The improvement remained at 12 months. MRI analysis revealed the presence of scaffolds at 6 months, with evidence of some tissue integration in many improvements in scaffold morphology and ICRS classification of cartilage in the medial compartment were noted at 12 months. No synovitis was noted in the joint or adverse reactions in the other compartments., Conclusion: The new Actifit(®) polyurethane scaffold has been shown to be a safe, effective implant, for the treatment of patients with pain as a result of segmental medial meniscus loss at 1 year., Level of Evidence: IV.

Introduction: The aim of this study was to assess the reproducibility of magnet resonance imaging (MRI) analysis of preserved anatomic structures of the knee after patellofemoral replacement (PFR). It was hypothesized that evaluation of cartilage, ligaments, meniscus and tendons would result in high inter-observer reliability after PFR., Material and Methods: MRI, tailored to reduce metallic artefacts of the knee, after PFR was performed in seven patients. Two independent investigators evaluated cartilage, menisci, collateral and cruciate ligaments, the quadriceps and patellar tendons and the presence of joint effusion. The reviewers used a five-point scale to give a degree of confidence to their evaluation of each parameter. Inter-observer reliability was determined by calculation of Cohen's Kappas., Results: Artefact provoked by the implants was not observed. For all assessed structures, there was excellent inter-observer reliability, with high Cohen's Kappas. There were also high levels of inter-observer agreement and observer confidence in the evaluation of cartilage, meniscus, tendons, ligaments and joint effusion., Conclusion: Tailored MRI allows reproducible analysis of the preserved knee joint structures after PFR. It might prove helpful in assessment of painful knee joints after PFR., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Purpose: The aim of the study is to describe and characterize the implant-bone interface of femoral, tibial and patellar components after TKA using magnet resonance imaging (MRI)., Scope: Fifty-five patients who underwent MRI modified to reduce artifacts after TKA were identified retrospectively from medical records. This included 27 TKA with a zirconium femoral component and 28 TKA with conventional cobalt/chrome/molybdenum alloy component (CoCrMo). The MRIs were evaluated by two blinded, independent investigators and Cohen's Kappa was applied to determine the interobserver reliability. Excellent visibility, interobserver agreement and reliability was found for the interface of the tibial components, patellar buttons, and for femoral components made of zirconium. Conventional CoCrMo components caused significant artifact that interfered with the evaluation of the interface of femoral components., Conclusion: MRI performed with a special protocol allows good reproducibility of analysis of implant-bone interface at tibia and patella after TKA. The femoral interface was visualized for components made of zirconium. Conventional CoCrMo femoral components caused considerable artifact and interfered with the evaluation of the femoral interface. MRI tailored to reduce metallic susceptibility artifact can be a helpful tool for evaluation of prosthesis bone interface and may be helpful for the diagnosis of component loosening., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Polyethylene wear is a key contributor to long-term failure in total knee arthroplasty. Oxidized zirconium alloy was created as a bearing surface for total joint arthroplasty in an attempt to address this concern. Oxidized zirconium has shown considerable improvements over existing materials in several key areas related to component longevity, including resistance to roughening, wear reduction, frictional behavior and biocompatibility. This review aims to summarize the current use of oxidized zirconium alloy in knee arthroplasty, as well as the possible advantages and downsides of this material.