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Purpose  Bone loss is a challenging problem during revision total knee arthroplasty (TKA). Several studies have been published on the use of metaphyseal sleeves during revision TKA. Therefore, the aim of this systematic review was to summarize the clinical and radiographic outcomes of the use of metaphyseal sleeves in the setting of revision TKA. Methods  A comprehensive search of PubMed, MEDLINE, CINAHL, Cochrane, EMBASE, and Google Scholar was performed, covering the period between January 1, 2000, and August 12, 2017. Various combinations of the following key words were used: "metaphyseal," "sleeves," "knee," and "revision." A total of 10 studies were included in the present systematic review. Results  A total of 904 patients with 928 implants were recorded with a mean age of 69 years. They were evaluated at a mean follow-up of 45 months. Overall 1,413 sleeves, 888 in the tibia and 525 in the femur, were implanted. There were 36 septic re-revisions of the prosthetic components (4%). Five sleeves were found loose during septic re-revision; therefore, the rate of septic loosening of the sleeves was 0.35%. An aseptic re-revision of the prosthetic components was performed 27 times (3%). Ten sleeves were found loose during aseptic re-revision; therefore, the rate of aseptic loosening of the sleeves was 0.7%. Intraoperative fractures occurred 44 times (3.1%). Finally, clinical outcome was improved at final follow-up. Conclusion  Metaphyseal sleeves demonstrate high radiographic signs of osteointegration, low septic loosening rate, low intraoperative fractures rate, and a good-to-excellent clinical outcome. Hence, they are a valid option to treat large metaphyseal bone defect during revision TKA. Level of Evidence  This is a systematic review of level IV studies., Competing Interests: Conflict of Interest None declared.

Purpose  The aim of the present retrospective study is to describe the results obtained at 2-year follow-up by using a porcine dermis-derived collagen membrane implanted as augmentation to treat large rotator cuff tears. Methods  Thirty-five patients in total were included according to the following criteria: large or massive rotator cuff tear, confirmed during surgery, measuring between 3 and 5 cm in width and stage 1 to 2 fatty infiltration documented at magnetic resonance imaging (MRI). Patients underwent arthroscopic repair of the cuff augmented by the implantation of a porcine dermal collagen membrane. Patients were evaluated up to 24 months after surgery by the Constant score and MRI imaging to assess functional outcomes and re-tear rate. The results obtained were compared to those of a matched cohort of 35 patients operated by arthroscopic repair alone by the same surgical team. Results  The application of the porcine membrane proved to be safe without scaffold-related adverse events documented. A statistically significant difference in the Constant score in favor of the treatment group was documented at the final evaluation ( p  = 0.036 ). Furthermore, a subgroup analysis revealed that patients treated by augmentation and presenting re-tear at MRI showed a significantly higher functional outcome compared with control patients with MRI evidence of re-tear ( p  = 0.0136). Conclusion  Arthroscopic repair augmented by porcine dermal xenograft for the treatment of chronic and retracted rotator cuff tears with low-grade fatty degeneration proved to be safe and also effective, with higher functional score compared with the arthroscopic repair alone. Level of Evidence  This is a Level III, retrospective cohort study.

Purpose  The purpose of this study was to compare, in terms of blood loss and implant alignment, a new generation of smart extramedullary (EM) cutting guides with the conventional intramedullary (IM) guide for total knee arthroplasty (TKA). The hypothesis was that the EM system would result in less blood loss and fewer days of hospitalization, while ensuring equal or higher accuracy in the alignment of the femoral implant. Methods  Thirty-six patients were enrolled for the present study: 18 patients underwent TKA using the EM guide and for the other 18 patients the IM guide was used. Preoperative and postoperative X-rays were acquired. The preoperative and postoperative hemoglobin values were compared. Lastly, length of hospital stay was recorded. Results  The hemoglobin difference was significantly lower in the EM group. The alignment of the prosthetic femoral implant in the two groups was comparable but all patients in the EM cohort had a final alignment within 3 degrees of range on the frontal view, while 22% of the patients in the IM cohort had a final alignment exceeding 3 degrees of range. The mean hospitalization duration showed no significant difference between groups, though EM group showed 1.6 days less compared with IM group. Conclusions  The inertial-based EM guide system could be useful for decreasing blood loss compared with conventional guide. This device tended to have better results even in terms of accuracy, but this difference was not significant. Level of Evidence  This is a level II, prospective cohort study.

Purpose  Metaphyseal bone defects are a challenge in complex primary and revision total knee arthroplasty (TKA). Recently, several studies have been published with promising results about the use of Trabecular Metal (TM) cones to address bone defects. The aim of this study is to review the literature to assess the efficacy of TM cones to address metaphyseal bone loss. Methods  A comprehensive search was performed on PubMed, Medline, CINAHL, Cochrane, Embase, and Google Scholar databases using various combinations of the following keywords: "metaphyseal," "cones," "tantalum," "knee," and "revision." Only papers reporting clinical data about the use of trabecular metal cones were included in the analysis. In vitro studies, case reports, surgical technique, or other studies where it was not possible to collect clinical data were excluded. Patients characteristics, details of the surgical procedures, outcome, and complications were collected from each included study. Results  No controlled studies were available in the literature and all the papers were case series. In 16 studies included, the records of 442 patients with 447 implants and 523 TM cones were reported. The mean follow-up was 42 months (range: 5-105) for 360 procedures. Among 437 procedures, 30.4% were septic revisions. The Anderson Orthopaedic Research Institute (AORI) classification was available for 352 defects: 13 type 1, 69 type 2A, 115 type 2B, and 155 type 3. To manage these 352 defects, 360 TM cones were implanted. Intraoperative fractures occurred 13 times (10 femoral/3 tibial), 6 required surgical fixation. The overall infection rate was 7.38%, and the infection rate for the aseptic procedures was 0.99%. An aseptic exchange was performed 13 times, among these procedures two TM cones were loose. Signs of loosening were found just in 1.3% of the 523 TM cones implanted (5 femoral/2 tibial) during 447 procedures. Conclusion  The TM cones are an effective solution to manage bone defects in complex primary and revision TKA at intermediate follow-up. The incidence of complications was low; however, the femoral metaphysis proved to be more susceptible to complications. Level of Evidence  Level IV, systematic review of level IV studies.

Magnetic scaffolds are becoming increasingly attractive in tissue engineering, due to their ability to enhance bone tissue formation by attracting soluble factors, such as growth factors, hormones and polypeptides, directly to the implantation site, as well as their potential to improve the fixation and stability of the implant. Moreover, there is increasing evidence that the synergistic effects of magnetic scaffolds and magnetic fields can promote bone repair and regeneration. In this manuscript we review the recent innovations in bone tissue engineering that exploit magnetic biomaterials combined with static magnetic fields to enhance bone cell adhesion and proliferation, and thus bone tissue growth.

Osteochondritis dissecans (OCD) is a rare yet fascinating disease affecting young, active patients. It remains a 'mysterious disease' whose etiopathology, still unclear, is the subject of ongoing studies aiming improving the knowledge of this condition and, therefore, treatment options, too. Even though the first descriptions of intra-articular loose bodies date back to very ancient times, it is only relatively recently that, thanks to the contribution of some very eminent physicians, it became recognized as a specific orthopaedic condition. The aim of the present manuscript is to trace the main steps in the journey that led to the acknowledgement of OCD as an autonomous clinical entity, and to recall the prominent figures involved.

Isolated posteromedial ankle dislocation is a rare condition thanks to the highly congruent anatomical configuration of the ankle mortise, in which the medial and lateral malleoli greatly reduce the rotational movement of the talus, and the strength of the ligaments higher than the malleoli affords protection against fractures. However, other factors, like medial malleolus hypoplasia, laxity of the ligaments, peroneal muscle weakness and previous ankle sprains, could predispose to pure dislocation. In the absence of such factors, only a complex high-energy trauma, with a rotational component, can lead to this event. Irreducibility of an ankle dislocation, which is rarely encountered, can be due to soft tissue interposition. Dislocation of the posterior tibial tendon can be the cause of an irreducible talar dislocation; interposition of this tendon, found to have slid posteriorly to the distal tibia and then passed through the tibioperoneal syndesmosis, is reported in just a few cases of ankle fracture-dislocation.

Purpose: dinamic roentgen stereophotogrammetric analysis (RSA), a technique currently based only on customized radiographic equipment, has been shown to be a very accurate method for detecting three-dimensional (3D) joint motion. The aim of the present work was to evaluate the applicability of an innovative RSA set-up for in vivo knee kinematic analysis, using a biplane fluoroscopic image system. To this end, the Authors describe the set-up as well as a possible protocol for clinical knee joint evaluation. The accuracy of the kinematic measurements is assessed., Methods: the Authors evaluated the accuracy of 3D kinematic analysis of the knee in a new RSA set-up, based on a commercial biplane fluoroscopy system integrated into the clinical environment. The study was organized in three main phases: an in vitro test under static conditions, an in vitro test under dynamic conditions reproducing a flexion-extension range of motion (ROM), and an in vivo analysis of the flexion-extension ROM. For each test, the following were calculated, as an indication of the tracking accuracy: mean, minimum, maximum values and standard deviation of the error of rigid body fitting., Results: in terms of rigid body fitting, in vivo test errors were found to be 0.10±0.05 mm. Phantom tests in static and kinematic conditions showed precision levels, for translations and rotations, of below 0.1 mm/0.2° and below 0.5 mm/0.3° respectively for all directions., Conclusions: the results of this study suggest that kinematic RSA can be successfully performed using a standard clinical biplane fluoroscopy system for the acquisition of slow movements of the lower limb., Clinical Relevance: a kinematic RSA set-up using a clinical biplane fluoroscopy system is potentially applicable and provides a useful method for obtaining better characterization of joint biomechanics.

At the current state of the art in anterior cruciate ligament (ACL) reconstruction, multiple techniques have been presented but none has given clearly defined and improved results. One of the main issues concerns the choice of graft. The concept of using xenograft tissue, defined as a graft tissue from one species and destined for implantation in an unlike species, was introduced in order to try to overcome the mechanical and biological concerns associated with synthetic materials and the safety and quality concerns and availability problems of allograft tissue. Xenograft tissue carries the risk of producing an immunological reaction. In order to try to overcome or attenuate the immune response against porcine xenograft tissue, the Z-Process® (Aperion Biologics Inc, San Antonio, Texas, USA) has been developed and used to produce the Z-Lig® family of devices for ACL reconstruction procedures. Z-Lig® is a tendon graft with or without bone blocks, sourced from animal tissue in a manner consistent with what has normally been sourced from human tissue, and processed to overcome anti-Gal-mediated rejection and to attenuate other immunological recognition in humans. All this while ensuring sterility, viral inactivation and preservation of mechanical proprieties appropriate for an ACL reconstruction device. The Z-Lig® device has been tested in skeletally mature monkeys and given interesting and promising results from the preclinical performance and safety profile point of view. On this basis, it was possible to proceed with the first clinical trial involving humans, which gave similar encouraging results. The Z-Lig® device has also been implanted in Italy at the Rizzoli Orthopaedic Institute in Bologna, as a part of international multicenter prospective randomized blinded controlled study aimed at comparing xenograft with allograft tissue.

Allowing a patient to return to sport and unrestricted physical activity after ACL injury and reconstruction is one of the most challenging and difficult decisions an orthopaedic surgeon has to make. Indeed, many factors have to be taken into account before it can be considered safe for a patients to load a reconstructed knee. The current literature contains plenty of studies aimed at evaluating return to sport, and the factors that may affect or predict this outcome, e.g. intrinsic factors like genetics, biology, type of lesion, anatomical features, motivation and psychology, and extrinsic factors such as graft type, surgical technique, rehabilitation protocols, and biological support. It is possible that awareness of these issues could help the clinician to optimise outcomes, and possibly avoid failures too, although as yet no universal criteria for resuming sport have been produced.

The main purpose of this article was to describe in detail, from the perspective of the clinical end user, a previously presented non-invasive methodology, applied in the treatment of anterior cruciate ligament injury, in which inertial sensors are used to quantify the pivot shift test. The outcomes obtained and relative considerations were compared with findings emerging from a review of the relevant updated literature. The detailed description here provided covers the system, the parameters identified and the testing procedure; it also includes the technical specifications of the hardware, the features introduced in the updated version of the software and the application of the system in clinical practice. The comparison of the technical considerations and clinical results with the updated literature confirmed the system's optimal ergonomics, good reproducibility and clinical reliability. The novel approach here analyzed has been shown to overcome the weaknesses of other available devices and systems. Therefore, since it can be considered a new paradigm in the quantification of pivot shift test, we can recommend its routine use in clinical practice.

Purpose: the aim of this study was to describe the clinical results obtained after intra-articular injection of a leukocyte-poor platelet-rich plasma (PRP) preparation for the treatment of knee osteoarthritis (OA)., Methods: forty-five patients (mean age: 59 years, mean BMI: 27) were included and treated with a cycle of three weekly injections of autologous conditioned plasma. Six patients were affected by bilateral symptomatic OA, therefore 51 knees in total were treated. The patients were divided into two groups: those affected by early/moderate OA and those affected by severe OA. The patients were submitted to baseline evaluation and evaluation after a mean follow-up of 14.5 months (range: 6-24 months), performed using the following outcome measures: IKDC-subjective, EQ-VAS, Tegner, and KOOS scores. Adverse events and patient satisfaction were also recorded. The results in the two groups of patients ("early/moderate" vs "severe OA") were analyzed separately., Results: the overall clinical outcome was positive and the treatment proved to be safe. In the "early/moderate OA" group, the IKDC-subjective score increased from 36.4 at the baseline evaluation to 57.3 at the follow-up (p<0.0005) and a similar trend was shown by the EQ-VAS, Tegner, and KOOS scores. Although an improvement was also recorded in the "severe OA" group, the clinical outcome of the patients in this group was significantly poorer and they reported less benefit. In the "early/moderate OA" group, BMI and longer symptom duration before treatment were found to be correlated with clinical outcome., Conclusions: PRP injections are capable of reducing pain and improving knee functional status at short-term follow-up. The patients with a lower degree of joint degeneration were the best responders, whereas in severe osteoarthritic knees this biological treatment, used as a "salvage procedure", produced a less favorable outcome., Level of Evidence: level IV; therapeutic case series.

There is currently a growing demand for unicompartmental knee replacement (UKR) to treat degenerative osteoarthritis or osteonecrosis of a single compartment of the knee. This procedure has evolved significantly over the past three decades and we here present a brief review of the literature on this topic. This historical overview traces the hypotheses that have led to the modern state of the art in minimally invasive UKR surgery and to the revival of the concept of interpositional hemiarthroplasty.

The patellofemoral joint, due to its particular bone anatomy and the numerous capsuloligamentous structures and muscles that act dynamically on the patella, is considered one of the most complex joints in the human body from the biomechanical point of view. The medial patellofemoral ligament (MPFL) has been demonstrated to contribute 60% of the force that opposes lateral displacement of the patella, and MPFL injury results in an approximately 50% reduction in the force needed to dislocate the patella laterally with the knee extended. For this reason, recent years have seen a growing interest in the study of this important anatomical structure, whose aponeurotic nature has thus been demonstrated. The MPFL acts as a restraint during motion, playing an active role under conditions of laterally applied stress, but an only marginal role during natural knee flexion. However, it remains extremely difficult to clearly define the anatomy of the MPFL and its relationships with other anatomical structures.