The Trochlear Bisector as a New Landmark for Kinematic Alignment in Total Knee Arthroplasty: A Radiographic Study.

Background: In recent years, there has been considerable interest in prosthetic alignment techniques for total knee arthroplasty (TKA), particularly in the so-called kinematic alignment, which aims to restore the knee's native alignment. However, implementing this technique requires specialized instruments and procedural steps that can be laborious. This study introduces the bisector of the trochlear groove as a reliable landmark for performing the distal femoral cut while maintaining parallelism with the native femoral joint line. Methods: Three orthopedic specialists assessed 110 X-ray images of full-leg, weight-bearing lower limbs obtained from healthy individuals between January 2021 and December 2022. The bisector of the trochlear groove was identified on the X-ray images, and the angle between this bisector and the femoral joint line was measured. The consistency of these measurements across repeated assessments and different examiners was evaluated. Results: The bisector of the trochlear groove was found to be perpendicular to the femoral joint line, with a mean angle of 89.4°. The inter-rater reliability was 68% within ±1.3° from the mean, while the intra-rater reliability was 82% within ±1.5° from the mean. Conclusions: These results suggest that by performing a femoral cut perpendicular to the bisector of the trochlear groove, surgeons can inherently restore the femoral joint line of the native knee in patients where the native joint line is no longer identifiable due to the effect of osteoarthritis. This method may offer a viable and straightforward alternative to the standard surgical technique currently practiced for kinematic alignment in TKA.

A Low-Cost Sensing Solution for SHM, Exploiting a Dedicated Approach for Signal Recognition.

Health assessment and preventive maintenance of structures are mandatory to predict injuries and to schedule required interventions, especially in seismic areas. Structural health monitoring aims to provide a robust and effective approach to obtaining valuable information on structural conditions of buildings and civil infrastructures, in conjunction with methodologies for the identification and, sometimes, localization of potential risks. In this paper a low-cost solution for structural health monitoring is proposed, exploiting a customized embedded system for the acquisition and storing of measurement signals. Experimental surveys for the assessment of the sensing node have also been performed. The obtained results confirmed the expected performances, especially in terms of resolution in acceleration and tilt measurement, which are 0.55 mg and 0.020°, respectively. Moreover, we used a dedicated algorithm for the classification of recorded signals in the following three classes: noise floor (being mainly related to intrinsic noise of the sensing system), exogenous sources (not correlated to the dynamic behavior of the structure), and structural responses (the response of the structure to external stimuli, such as seismic events, artificially forced and/or environmental solicitations). The latter is of main interest for the investigation of structures' health, while other signals need to be recognized and filtered out. The algorithm, which has been tested against real data, demonstrates relevant features in performing the above-mentioned classification task.

All-Polyethylene Versus Metal-Backed Tibial Components in Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: In the literature, there is no evidence suggesting the superiority in clinical performance between all-polyethylene (AP) and metal-backed (MB) tibial implants in total knee arthroplasty. The aim of this study was to systematically review the literature to collect only high-quality studies investigating the differences in terms of clinical and radiostereometric analysis (RSA) outcomes of AP compared to MB implants. METHODS: Only randomized controlled trials (RCTs) reporting either clinical or RSA outcomes have been included. Data sources were Embase, Medline, and the Cochrane Central Register of Controlled Trials. RESULTS: We included eleven RCTs evaluating the outcomes of 1,377 patients. Of the RCTs, 9 of them showed a low risk and 2 showed moderate risk of bias. There was no statistically significant difference in terms of clinical outcomes and survival rate between the AP and MB group; however, a statistically significant lower mean lift-off in the AP group (0.19 mm) compared to the MB group (0.3 mm) was observed on RSA. CONCLUSIONS: The performance of AP total knee arthroplasty in terms of clinical outcomes and 5-year survival was not statistically different when compared to the MB group. However, the RSA showed a statistically significant lower mean lift-off in the AP group.

Assessing the impact of obturation techniques, kinematics and irrigation protocols on apical debris extrusion and time required in endodontic retreatment.

The aim of the study was to evaluate the impact of kinematics and irrigation protocols on the extrusion of apical debris during removal of different obturation techniques. A total of 144 single-rooted teeth were instrumented and obturated with Thermafil+AH Plus, Thermafil+AH Plus Bioceramic and single gutta-percha cone+AH Plus Bioceramic. Samples were divided according to the retreatment kinematics: continuous rotation or Jeni motion. Each sub-group was subjected to conventional irrigation or irrigation activated by EDDY. Extruded debris was collected in Eppendorf tubes, weighted and retreatment time was digitally recorded. Data were analysed with two-way ANOVA (p < 0.05). Debris extrusion was not significantly different between all groups. EDDY activation system and CanalPro Jeni required significantly longer time compared with other groups to remove Thermafil+AH Plus and single cone+AH Plus Bioceramic. Within current limitations, obturation technique, irrigation protocol and kinematics tested had no influence on apical extrusion debris, while they significantly impacted the retreatment time.

Sub-optimal femoral fit in total knee arthroplasty, a systematic review of human femoral data vs off-the-shelf contemporary femoral components.

PURPOSE: The purpose of the current study is to investigate the inadequacy of fit between the human distal femur and the knee implants offerings and describe the available strategies to overcome this issue. METHODS: A systematic research of the literature was performed to identify studies reporting morphologic measures of the distal femur. Studies were excluded if they included unhealthy knees or the morphological analysis did not report the two key dimensions to identify the patient's unique anatomy: AP length and mediolateral (ML) width. Clinically relevant component overhang or underhang was considered when the metal-bone mismatch was > 3 mm as described in the literature. RESULTS: Six studies with anthropometric analysis of 1395 distal femurs met the inclusion criteria. The analysis revealed that by employing the available sizes of four current "state-of-the-art" primary off-the shelf (OTS) femoral implants up to 13-41% would show underhang and 9-27% overhang clinically relevant and the introduction of narrower sizes did not reduce this percentage of underhang but improved the overhang rate of 10-15%. CONCLUSIONS: Whenever an ML/AP mismatch in encountered in the operating room, adaptations are needed, and these bring about deleterious biomechanical and clinical complications. Therefore, this study highlights the need for implants design with multiple ML offerings per AP size, since they provide not only more sizes options but more femoral shapes to match the different ML sizes of the distal femur, compared to designs with single ML offerings for a given femoral AP dimension.

Biologic agents to optimize outcomes following ACL repair and reconstruction: A systematic review of clinical evidence.

Treatment options for anterior cruciate ligament (ACL) injuries have greatly developed over the past decades. Although reconstruction surgery is a concrete reality, stimulation of ACL healing through biological techniques could represent a revolutionary conservative approach. The use of biologic products, such as platelet-rich plasma (PRP) or mesenchymal stem cells (MSCs), to treat partial ruptures or to enhance ligamentization after reconstruction, could thoroughly improve clinical outcomes. The aim of the present paper is to systematically review the available literature on this topic, to (i) describe the current state of the art in available biologic techniques; (ii) clarify the outcomes of their application; (iii) identify areas needing further investigation and possible future development. A systematic review of the literature on the use of biologically active agents (PRP and MSCs) to enhance outcomes of ACL surgery was performed: 31 studies were included. Based on the ACL injury pattern, 6 papers investigated biologic agents in ACL partial tears whereas 25 papers in ACL reconstruction. Sixteen of twenty-five studies dealing with ACL reconstruction were randomized controlled trials, whereas only case series are available for partial ACL tears. Current evidence is still lacking sound data to support the use of biological agents: no clinical superiority has been described when using PRP in ACL reconstruction. Concerning ACL healing in partial tears, the application of PRP has led to encouraging outcomes, but these findings should be confirmed by appropriately designed RCTs.

Evaluation of the root filling quality with experimental carrier-based obturators: a CLSM and FEG-SEM analysis.

This study evaluated tubule penetration of GuttaFlow Bioseal with cold single cone or carrier-based technique, under confocal laser scanning microscopy (CLSM). Twenty straight single-rooted teeth were instrumented with Hyflex CM and divided in two groups (n = 10) according to the obturation method: single cold gutta-percha cones; experimental carrier-based obturators. GuttaFlow Bioseal, labelled with Rhodamine B dye, was used as sealer in both groups. Teeth transversally sectioned were observed under CLSM. Percentage of sealer penetration and integrity of sealer layer perimeter were measured. Surface and microstructural characteristics of obturators and gutta-percha cones were compared by FEG-SEM and EDX analysis. No significant differences were found between groups for each examined parameter. Significant differences (P < 0.05) were reported mainly within groups. Integrity was similar among and within groups. FEG-SEM/EDX analysis of obturators revealed the presence of Ba and Zn. Carrier-based obturation technique associated with GuttaFlow Bioseal does not seem to affect sealer penetration into dentinal tubules.

Retreatment of Experimental Carrier-Based Obturators with the Remover NiTi Instrument: Evaluation of Apical Extrusion and Effects of New Kinematics.

The objective of this study is to evaluate the retreatment time and weight of apically extruded debris yielded by two different kinematics during the removal of different root canal filling materials. Forty straight single-rooted extracted teeth were instrumented with HyFlex CM files and obturated with two different techniques: 25.04 HyFlex experimental carrier-based obturators (Coltène/Whaledent, Altstätten, Switzerland) (group 1) or 25.04 single gutta-percha cones (Roeko Coltène/Whaledent, Altstätten, Switzerland) (group 2) and Guttaflow Bioseal as the sealer. Samples were divided into four subgroups (n = 10) according to the used kinematics for the removal of root canal filling materials: continuous rotation (A) or retreatment motion (B) with a Remover and HyFlex EDM Nickel-Titanium instruments activated with a CanalPro Jeni micromotor (Coltène/Whaledent, Altstätten, Switzerland). Time for retreatment was digitally recorded, and debris extruded from the apex was collected in Eppendorf tubes and weighted with an analytical balance. Data on retreatment time and apical extrusion were statistically analyzed with the Kruskal-Wallis test (p < 0.05). Working length was achieved in all the retreated samples. The removal of root filling material resulted significantly faster with the Jeni mode (p < 0.001), and the difference was significant for the removal of both filling materials (p < 0.05). No significant differences on debris extrusion between single cone and experimental obturators groups were noted (p > 0.05), and no significant differences between kinematics (continuous rotation vs. Jeni motion) were observed (p > 0.05). All the tested retreatment strategies lead to an extrusion of material from the apex, and the weight of apically extruded debris was similar. The use of the innovative CanalPro Jeni kinematics accelerates the time for the removal of root filling materials.

In-Depth Metallurgical and Microstructural Analysis of Oneshape and Heat Treated Onecurve Instruments.

OBJECTIVE: To define surface, mechanical, microstructural and metallurgical features of conventional One-Shape (OShape) and heat-treated OneCurve (OCurve) nickel-titanium instruments. METHODS: Instruments were analysed by scanning electron microscopy (SEM) on new instruments and after simulated clinical use (SCU). Cyclic fatigue testing was performed and the number of cycles to fracture (NCF) and the length of the fractured instruments were measured (Mann-Whitney test). Fractured instruments during cyclic fatigue testing were then inspected by SEM fractographic analysis. Field emission gun scanning scanning electron microscopy (FEG-SEM), energy-dispersive X-ray spectroscopy (EDX) and micro-Raman spectroscopy were used to assess alloy surface chemistry. Focused ion beam (FIB) was performed to analyse the oxide layer on the surface of OCurve before and after SCU. X-Ray diffraction (XRD), metallographic evaluation and differential scanning calorimetry (DSC) were used to determine martensitic/austenitic phase transformation temperatures. RESULTS: SEM observations on new instruments revealed a smooth regular surface with flattened milling grooves. No wear features were detected after SCU. OCurve exhibited a higher cyclic fatigue resistance (P<0.05), slower crack propagation and a surface layer of TiO2. Metallographic analysis and XRD showed the prevalence of martensitic grains on OCurve instruments that were stable at body temperature as confirmed by DSC analysis. Furthermore, DSC demonstrated a shift in the temperature transformation ranges suggesting an increase of martensite phase in autoclaved OCurve instruments. CONCLUSION: Heat treatment processes were confirmed as a valid enhancement of the properties of the new generation NiTi instruments. OCurve presented a significant improvement over OShape regarding both mechanical and metallurgical characteristics.

Combining apical torsional load and cyclic fatigue resistance of NiTi instruments: New approach to determine the effective lifespan of rotary instruments.

In the described proof-of-principle experiments, we introduced a novel testing device to investigate how different concurrent torsional loads influence the cyclic fatigue (CF) resistance of a nickel-titanium (NiTi) instrument. The device was designed to test CF resistance of NiTi files with a standardized load on the apical 5 mm; a movable cylinder controlled by a lever provided a uniform real-time load. Thirty-three NiTi instruments 25.04 (F360, Komet, Lemgo, Germany) were rotated until fracture at 30° curvature under three different torsional loads (n = 11 each); Group A: 2.5 Ncm; Group B: 5 Ncm; Group C: 10 Ncm. anova, multiple comparisons Tamhane tests, regression and Kaplan-Meyer analysis were performed to contrast means. Resistance to cyclic fatigue differed significantly among groups (P = 0.0001). Increased torsional loads led to a decrease in time to failure. An inverse correlation (r = -0.721, P = 0.001) was observed between time and torsional load, with higher torsional loads correlated to shorter times to fracture.

The reliability of adductor tubercle as an anatomical landmark for joint line restoration in revision knee arthroplasty: a systematic review.

Joint line (JL) restoration is one of the major challenges in revision total knee arthroplasty (rTKA). There is debate regarding the most reliable methodology for the assessment of JL level during revision surgery. Among the strategies, the use of adductor tubercle (AT) as an anatomical landmark has been proposed. The purpose of this paper is to systematically review the available literature to understand the reliability of AT ratio to identify the JL, and the advantages and drawbacks of its application. A research was performed on the PubMed, Embase, Cochrane and Google Scholar databases based on the following inclusion criteria for articles' selection: (I) clinical reports of any level of evidence, (II) written in the English language, (III) published from 2010 to 2020, (IV) dealing with the use of the adductor tubercle as a landmark to restore JL in revision TKA. All relevant data were extracted by two independent investigators, and discrepancies were resolved by discussion and consensus. A total of 13 studies were included: nine were radiographic evaluations, 3 clinical reports and 1 was an ex-vivo study. Radiographic studies highlighted that AT is a landmark easy to identify, with high intra and inter-observer agreement, irrespective of gender, age and size of the patient. The comparison with other bony landmarks revealed superior reliability in favor of AT. Also during surgical procedures, AT can be safely located and some clinical studies confirmed that AT ratio helps surgeon in re-establishing a correct JL and achieve ligament balancing even in complex revision cases. AT is a reliable and easily detectable landmark, and AT ratio is a valid tool to determine the JL level and help surgeons to restore the JL and simultaneously achieve knee ligament balancing in r-TKA.

Knee Intraosseous Injections: A Systematic Review of Clinical Evidence of Different Treatment Alternatives.

OBJECTIVE: To systematically review the available clinical evidence regarding the safety and efficacy of knee intraosseous injections for the treatment of bone marrow lesions in patients affected by knee osteoarthritis. DESIGN: A literature search was carried out on PubMed, Embase, and Google Scholar databases in January 2020. The following inclusion criteria were adopted: (1) studies of any level of evidence, dealing with subchondral injection of bone substitute materials and/or biologic agents; (2) studies with minimum 5 patients treated; and (3) studies with at least 6 months' follow-up evaluation. All relevant data concerning clinical outcomes, adverse events, and rate of conversion to arthroplasty were extracted. RESULTS: A total of 12 studies were identified: 7 dealt with calcium phosphate administration, 3 with platelet-rich plasma, and 2 with bone marrow concentrate injection. Only 2 studies were randomized controlled trials, whereas 6 studies were prospective and the remaining 4 were retrospective. Studies included a total of 459 patients treated with intraosseous injections. Overall, only a few patients experienced adverse events and clinical improvement was documented in the majority of trial. The lack of any comparative evaluation versus subchondral drilling alone is the main limitation of the available evidence. CONCLUSIONS: Knee intraosseous injections are a minimally invasive and safe procedure to address subchondral bone damage in osteoarthritic patients. They are able to provide beneficial effects at short-term evaluation. More high-quality evidence is needed to confirm their potential and to identify the best product to adopt in clinical practice.

High survivorship rate and good clinical outcomes at mid-term follow-up for lateral UKA: a systematic literature review.

PURPOSE: The purpose of this paper is to systematically review the available literature to understand the effectiveness, the survivorship, the clinical outcomes and the complications of lateral UKA. METHODS: A review of the current literature available about lateral UKA was performed in March 2020, according to the PRISMA guidelines. Selection was based on the following inclusion criteria: (1) clinical reports of any level of evidence, (2) written in English language, (3) published from 1996 to 2020, (4) dealing with clinical data on lateral UKA. A total of 47 articles, published between 1996 and 2020, were included in the review. Quality of every article was assessed using the Modified Coleman Methodology Score. RESULTS: A total of 47 studies were included. Mean mCMS was 45.27 (range 30-62). Mean age at surgery was 64.5 years (range 34.1-88.0 years). In 1741 patients (65.5%) a metal back implant was used and in 421 patients (15.8%) an all poly design was used. Several scores were used to evaluate clinical results (OKS, AKSS, IKS, KOOS, WOMAC, VAS). Range of motion improved with an overall mean value of 120.3° (range: 105.9°-143.3°). The mean follow-up was 60.7 months (range, 7-204 months), mean survivorship (absence of a revision) with a minimum 60 months of follow-up was 88.6% (range 74.5-100) and mean satisfaction of patients was 78.5% (range 41.0-97.9). CONCLUSIONS: Lateral UKA seems to be an effective solution to manage lateral osteoarthritis (OA), based on preliminary results, with survivorship and satisfaction rate comparable to medial UKA and total knee arthroplasty (TKA). Nonetheless, this review highlights that the quality of studies available in current literature is low. LEVEL OF EVIDENCE: Systematic review of level IV studies.

In vitro validation of a novel inertial-based cutting guide for tibial resection in total knee arthroplasty.

BACKGROUND: Correct component alignment in total knee arthroplasty (TKA) is crucial for implant functionality and longevity. Several devices have been developed to help surgeons to achieve optimal component positioning. The purpose of our study was to evaluate the accuracy and reliability of a novel inertial-based cutting guide used to perform tibial resection in TKA taking into account users with different levels of experience. METHODS: Seven operators (raters) with different levels of experience participated in the study. To evaluate the accuracy, the varus/valgus (VV) and slope (SL) angles obtained with this novel device were compared with the reference angles obtained with the navigation system. To calculate intra-(rater) reliability repeated measurements of VV and SL angles by the same operator were used. To calculate inter-(rater) reliability repeated measurements of VV and SL by different operators were used. RESULTS: A total of 140 acquisitions were performed. In this study both for the VV and for the SL the maximum mean absolute error (MAE) that the inertial system registered was <1°. Intra-inter reliability was evaluated by calculating the Fleiss' Kappa coefficient, which recorded values close to 0.75 (75%) with regard to the VV and the SL for intra-reliability, while values were recorded around 0.9 (90%) for the inter subject reliability. CONCLUSIONS: The Perseus system is accurate, reliable and surgeon-friendly and could be very useful in improving results in low-volume centers.

Knee kinematics after cruciate retaining highly congruent mobile bearing total knee arthroplasty: An in vivo dynamic RSA study.

PURPOSE: This work presents a kinematic evaluation of a cruciate retaining highly congruent mobile bearing total knee arthroplasty design using dynamic Roentgen sterephotogrammetric analysis. The aim was to understand the effect of this implant design on the kinematics of prosthetic knees during dynamic activities. METHODS: A cohort of 15 patients was evaluated at nine month follow-up after surgery. The mean age was 74.8 (range 66-85) years. The kinematics was evaluated using the Grood and Suntay decomposition and the Low-Point (LP) methods. RESULTS: ?tlsb=-0.15pt?>From sitting to standing up position, the femoral component internally rotated (from -11.3 ±â€¯0.2° to -7.0 ±â€¯0.2°). Varus-valgus rotations were very close to 0° during the whole motor task. LP of medial condyle moved from an anterior position of 12.0 ±â€¯0.2 mm to a posterior position of -12.4 ±â€¯0.2 mm; LP of the lateral condyle moved from an anterior position of 8.1 ±â€¯0.2 mm to a posterior position of -12.4 ±â€¯0.2 mm, showing a bi-condylar rollback where both condyles moved parallel backward. Moreover, the femoral component showed anterior translation with respect to the tibia from 80° to 20° (from -4.9 ±â€¯0.2 mm to 3.3 ±â€¯0.2 mm), then a posterior translation from 20° to full extension was identified (from 3.3 ±â€¯0.2 mm to 0.5 ±â€¯0.2 mm). CONCLUSIONS: Paradoxical anterior femoral translation and absence of medial-pivoting motion were recorded, highlighting the role of the symmetric deep dishes insert as main driver of the kinematic of this TKA design.

Oxygen-Ozone Therapy for the Treatment of Knee Osteoarthritis: A Systematic Review of Randomized Controlled Trials.

PURPOSE: To review the available literature on the application of oxygen-ozone therapy (OOT) in the treatment of knee osteoarthritis (KOA) to understand its therapeutic potential and to compare it with other conservative treatment options. METHODS: A systematic review of the literature was performed on the PubMed, Cochrane, Embase, ResearchGate, and PedRo Databases, with the following inclusion criteria: (1) randomized controlled trials (RCTs), (2) written in English, (3) published on indexed journals in the last 20 years (1998-2018), (4) dealing with the use of ozone intra-articular injection for the treatment of KOA. The risk of bias was assessed by the Cochrane Risk of Bias tool for RCTs. RESULTS: Eleven studies involving 858 patients in total (629 female and 229 male) were included. Patients in the control groups received different treatments: placebo in 1 trial; hyaluronic acid in 2 studies; hyaluronic acid and PRP in 1 trial; corticosteroids in 4; and hypertonic dextrose, radiofrequency, or celecoxib + glucosamine in the remaining 3 trials. In looking at the quality of the available literature, we found that none of the studies included reached "good quality" standard, 2 were ranked as "fair," and the rest were considered "poor." No major complications or serious adverse events were reported following intra-articular OOT, which provided encouraging pain relief at short term. On the basis of the available data, no clear indication emerged from the comparison of OOT with other established treatments for KOA. CONCLUSIONS: The analysis of the available RCTs on OOT for KOA revealed poor methodologic quality, with most studies flawed by relevant bias, thus severely limiting the possibility of drawing conclusions on the efficacy of OOT compared with other treatments. On the basis of the data available, OOT has, however, proven to be a safe approach with encouraging effects in pain control and functional recovery in the short-middle term. LEVEL OF EVIDENCE: Systematic review of Level I and III studies.

Correction to: The fate of root canals obturated with Thermafil: 10-year data for patients treated in a master's program.

The author names in the original version of this article were inadvertently interchange. Correct presentation of author names is reflected here.

Innovative regenerative medicine in the management of knee OA: The role of Autologous Protein Solution.

Osteoarthritis (OA) is one of the most common causes of chronic disability in adults due to pain and altered joint function. Although most patients report pain and functional limitation, symptoms, age of onset and disease progression are extremely variable. While inflammation could play a central role in the OA pathogenesis and progression, many underpinning mechanisms are still unclear. A number of proinflammatory mediators have been found in OA joints and could play a role, such as IL-1, IL-6, IL-7, IL-8, IL-15, IL-17, IL-18, TNF-alpha, macrophage chemotactic protein (MCP)-1, interferon-induced protein (IP)-10, monokine induced by interferon (MIG), oncostatin M (OSM), growth-related oncogene (GRO)-alpha, chemokine (C-C-motif) ligand 19 (CCL19), macrophage inflammatory protein (MIP)-1beta, and TGF-alpha. Biological approaches have recently got increasing interest due to their anti-inflammatory and immunomodulatory properties, regenerative potential, and high tolerability. The primary aim of this paper is to report the current concepts on regenerative medicine for knee OA with a particular focus on Autologous Protein solution (APS). APS is a blood derived product obtained by using a proprietary device, made of APS Separator, which isolates WBCs and platelets in a small volume of plasma, and APS Concentrator, which further concentrates platelets, WBCs and plasma proteins. The result is a peculiar formulation differing from other biologic products as it contains high levels of growth factors (EGF, IGF-1, PDGF-AB, PDGF-BB, VEGF, TGF-ß1) along with high concentrations of anti-inflammatory mediators (IL-1ra, sIL-1RII, sTNF-RI, sTNF-RII) and low levels of pro-inflammatory cytokines (Il-1ß and TNF-α). While emerging evidence supports the use of APS, as confirmed by in vitro studies and preliminary clinical results, the real clinical potential of APS and its benefits are still under investigation.

Early Failure in Medial Unicondylar Arthroplasty: Radiographic Analysis on the Importance of Joint Line Restoration.

Survivorship of unicondylar knee arthroplasty (UKA) remains a drawback, especially compared with the outcome of total knee arthroplasty. This could be improved by identifying and correcting failure mechanisms. To this purpose, this study aimed at exploring failure modalities of UKA, with particular focus on the role of joint line (JL) position and alignment as variable to be optimized for a successful outcome. This study explored modes of failure in 266 medial UKAs. Radiological comparison was performed between 24 failures and 24 matched controls, to determine the importance of UKA positioning in terms of femorotibial angle (FTA), tibial plateau angle, and posterior tibial slope (PTS). Radiographic comparative analysis showed statistically significant differences in the failure group compared with the control group in terms of variation in FTA (p = 0.0222), PTS (p = 0.0025), and JL height (p = 0.0022). Variations not only in FTA but also PTS and JL height were correlated with failures observed in this series. Thus, based on the results of this study, it emerges that JL position should be carefully controlled in all planes while implanting a UKA. This is a Level III, case-control study.