Use of dual-mobility cup in primary total hip arthroplasties: an Italian regional register (RIPO) study on three thousand, seven hundred and ten cases.

PURPOSE: The purpose of the study was to investigate the outcome of dual-mobility cup (DM) compared with a standard cup (SC) in primary total hip arthroplasty (THA) in the long-term follow-up based on a regional Italian joint registry (RIPO). METHODS: The Registry of Prosthetic Orthopaedic Implant (RIPO) was consulted, looking for all primary THAs implanted from 2000 to 2019. Three thousand seven hundred ten were dual-mobility cup (DM) total hip arthroplasties (THA) and 85.816 were standard cup (SC) THAs, on a total of 89.526 primary THA. Demographics, survival rates and causes of revision were evaluated and compared between the two groups. RESULTS: The use of DM progressively increased from 0.4% in 2000 to 7.5% in 2018 of all primary THAs. Revision rate was 3.5% (128 on 3710) for DMC and 4.7% (4061 on 85,816) for SC. DM presented lower dislocation rate if compared to SC with 22-28-mm femoral head diameter. However, DM showed a higher risk of revision for any causes than SC with 32-mm femoral head diameter in long-term follow-up. Nevertheless, no significant difference was measured in terms of demographics and surgical approach for dislocation rate. CONCLUSIONS: The DM cup represents a valid implant solution and has a lower dislocation rate than 22-28-mm SC. A slight increase in the use of DM implants over time was observed in the RIPO. However, a larger population and a longer follow-up are needed to further monitor the survival rate of new-generation DM implants.

Dual mobility cup in hip arthroplasty: An in-depth analysis of joint registries.

Although total hip arthroplasty (THA) has shown successful results, instability remains a major complication. In recent years, dual mobility cups (DMC) have gained interest among clinicians thanks to its low rate of dislocation and good clinical results. The main aim of this work was to describe the accuracy of data on DMC from national and regional joint registries (JRs) and the available worldwide literature. We identified topics on DMC among JRs to propose a new harmonized and standardized section for DMC with the aim to understand its surveillance over the time. We extracted survival and implant data for a separate analysis. After performing a critical exclusion process, nine JRs were considered eligible and included for final synthesis; these were the results from the available worldwide data from JRs. In our study, eight analyzed JRs reported a slight increase in DMC use in the last decade. In all the JRs evaluated and the available articles, dislocation remains one of the main reasons for revision and re-revision in hip arthroplasties. DMC is considered to be a valid construct increasingly used worldwide in primary and revision THA with the primary aim of reducing dislocation rates. Annual reports from JRs collect heterogeneous and low-quality information about outcomes and surveillance of DMC, creating a burden for clinicians to extract comparable data from different JRs. Longer follow-up and a systematic registering of DMCs with international registry harmonization are needed to monitor DMC outcomes.

Hip stability parameters with dual mobility, modular dual mobility and fixed bearing in total hip arthroplasty: an analytical evaluation.

BACKGROUND: Use of dual mobility (DM) in total hip arthroplasty has gained popularity due to the ability to reduce dislocation through increased jumping distance and impingement-free arc of movement. Recently, modular dual mobility (modDM) systems were introduced to give the possibility to use DM with standard metal-backed shells, however few has been studied to date regarding how jumping distance and the center of rotation change with modDM. The objective of this study was to evaluate, through analytical simulation, how jumping distance, center of rotation and arc of movement change between DM and standard cups with modDM or fixed bearings (FB). METHODS: 3D-models of DM and standard press-fit cups with modDM or FB liners were used to simulate DM, modDM and FB implant configurations, matched for same cup size, according to same cup position and different femoral head diameters. Jumping distance was calculated and center of rotation lateralization and oscillation angles were measured for each size of these three implant configurations. RESULTS: Jumping distance with modDM was reduced by -3.9 mm to -8.6 mm in comparison with DM, from 48 to 64 mm size, but resulted comparable to polyethylene 36 mm FB and increased by + 1.1 mm and + 1.4 mm than ceramic 36 and 40 mm FBs for sizes > 54 mm. ModDM lateralized the center of rotation up to + 2.5 mm and + 4.0 mm in comparison with DM and FBs, respectively. Oscillation angle with modDM resulted higher than + 16°, + 23°, + 17° and + 14° in comparison to DM, 28 mm, 32 mm and 36 mm FB cups, respectively, for 56 mm cup size. CONCLUSIONS: According to its specific design, modDM might change hip stability parameters in comparison to DM, worsening jumping distance and center of rotation position, but increasing arc of movement. As not restoring stability parameters in the same fashion, modDM implants should be properly used when DM cups are not feasible.

An uncommon case of irreducible ankle fracture-dislocation: the "Bosworth-like" tibio-fibular fracture.

An irreducible ankle-fracture dislocation characterized by the dislocation of the proximal fragment of the fibula posteriorly to the tibial tubercle is defined as "Bosworth injury". In the present report it is described, for the first time in literature, a complex case where the Bosworth injury was associated to a tibial plafond fracture: the proximal fibular fragment was entrapped between the tibial pilon and the fractured posterior tibial tubercle, which acted as a clamp, thus avoiding ankle reduction. Due to the presence of the tibial fracture, it was not possible to observe the typical radiological signs of Bosworth injury and therefore two unsuccessful reductions were attempted before performing a CT scan that revealed the complexity of the case, that required an immediate ORIF procedure to prevent the onset of complications.

Radiological identification of Zweymüller-type femoral stem prosthesis in revision cases.

INTRODUCTION: Since 1979 the number of patients treated with femoral stems has continued to grow, as well as the number of stems with features similar to the Zweymüller prosthesis produced by different companies. Identification can be problematic in case requiring revision. In the present paper, we present an overview of morphometric differences between the different stem designs, which can be useful for radiologic identification in revision cases. METHODS: By doing some research on the Internet of specialized sites and worldwide literature, we searched for all femoral stems agreeing with Zweymüller principles (cementless, straight, tapered, rectangular cross-sectioned femoral stems). RESULTS: We found 26 different stems from different companies producing or having produced in the past the Zweymüller-type femoral stems for hip prosthesis. DISCUSSION: Accurate preoperative identification of the Zweymüller femoral stem type may be of critical importance to eventual outcomes following revision surgery. Each manufacturer has different instruments specific to the removal of their primary implants, and ensuring they are available can simplify the revision procedure significantly. Exact pre-operative planning is also necessary for selecting the correct ball head in cases where a stem is well-fixed and can be left in situ. The commonly used notation "Eurocone 12/14" provides no information about the actual taper angle. Whenever the stem is left in situ, the exact specifications of the taper must therefore be obtained from the manufacturer in order to use a metal sleeve that precisely fits it and the ball head. Failure to do so may result in severe complications, such as metallosis. In cases where it is not possible to identify the taper angle, the surgeon may even consider removal of the stem, though this significantly increases the surgical procedure's invasiveness. Only a single, uniform standard taper, such as that offered until 1994 by CeramTec, can solve these issues in the future. CONCLUSION: The survival rate of the Zweymüller stems after ten years was 96 % and the complication rate was very low. Pre-operative identification of the femoral implant is of considerable importance for planning and correctly implementing revision procedures.

Correlation between cephalic screw positioning of Standard Gamma 3 Nail for intertrochanteric fractures and cut-out incidence.

INTRODUCTION: Lateral fractures of proximal femur are the most frequent fractures in elderly people. Internal fixation using medullary nails is the gold standard of treatment (Gamma 3 nail is the most implanted device) due to reduced incidence of complications than other devices. We report our experience in treating this kind of fractures with Gamma 3 nail, between January 2015 and December 2021. METHODS: We performed a retrospective cohort study of patients treated in our orthopaedic department; level of clinical care is III: 559 patients (431 females and 128 males, with an average age of 85.3 years) with lateral femoral neck fracture. All patients were surgically treated with Gamma 3 standard nail (SGN). We evaluated preliminary X-rays to classify fractures, according to AO-OTA classification and post-operative X-ray to verify cephalic screw position site, according to areas described by Cleveland in 1959: we measured tip-to-apex distance (TAD) and tip-to-apex calcar referred distance (CalTAD). Finally Chang reduction quality criteria (CRQC) for fracture reduction of trochanteric fractures were determined using preoperative or postoperative Antero-Posterior (AP) and lateral radiographs in a Picture Archiving and Communication System (PACS). Incidence of cut-out was evaluated in relation with these parameters. Patients were divided into 2 groups: first group had cephalic screw in optimal positions (5-8-9), the other group had cephalic screw in other positions. RESULTS: In 328 patients (58.7%) screw was in positions 5-8-9, in 231 patients (41.2%) screw was in not-optimal position. Median TAD was 19.1 ± 7.0 mm (range = 0.0-50.5); in 463 patients (82.8%) TAD was ≤ 25 mm. Median CalTAD was 21.4 ± 4.7 mm (range = 5.7-39.2); in 105 patients (79.4%) CalTAD was ≤ 25 mm. Cut-out was observed in 8 cases (1.43%). Multivariate analysis showed a significant correlation (p < 0,05) between incidence of cut-out and fracture type 31A2 and with TAD values >25 mm. Cephalic screw position did not influence incidence of cut-out. DISCUSSION: In order to obtain fracture healing with a low risk of failure, in particular cut-out, it is necessary to obtain good reduction of fracture and optimal lag screw position in order to achieve a TAD inferior to 25 mm.

Treatment of Periprosthetic Hip Fractures Vancouver B1 and C: The Significance of Bicortical Fixation. A Bicentric Study Comparing Two Osteosynthesis Systems.

INTRODUCTION The incidence of periprosthetic fractures (PFFs) is estimated to range from 0.1% to 4.1%1, due to the increasing prevalence of joint arthroplasties, coupled with an aging population. Numerous risk factors, including advanced age (>80 years), female gender, implant type, prior diagnoses of osteonecrosis and rheumatoid arthritis, revision surgery, aseptic stem mobilization, and the use of non-cemented stems, have been identified. Survivors of periprosthetic fractures often experience functional deterioration, facing a fourfold higher risk of hospitalization for postoperative complications compared to patients undergoing primary implantation, especially in the first postoperative year. MATERIALS AND METHODS Between 2018 and 2022, at the Maggiore Hospitals in Bologna and the San Matteo Policlinic in Pavia, we performed osteosynthesis on 84 patients with periprosthetic fractures of Vancouver type B1 or C. In 38 patients, we employed angular stable plates with the Zimmer Biomet NCB-PP® system. In 46 patients, we utilized INTRAUMA plates: DF distal femur and PFF proximal. Relevant postoperative follow-up outcomes considered included reintervention, infectious complications, radiographic healing, and functional recovery, with reference to changes in the Glasgow Outcome Scale (GOS) and the Harris Hip Score (HHS). All patients underwent clinical and radiographic evaluations during the follow-up period, averaging 28 months (range: 12-48 months), with a minimum follow-up duration of 12 months. RESULTS At the 4-month postoperative assessment, 71% of patients maintained their preoperative functional level, 19% experienced a 1-point GOS scale drop, and 10% died (GOS 5). The average HHS at 4 months was 80.2 points (range: 65-90). At the 6-month follow-up, 98.2% of patients achieved complete healing on radiographic examination. Only 1 patient (1.2%) developed a pseudoarthrosis site with synthesis device rupture. Only 1 patient (1.2%) required additional surgical treatment 2 years later due to the development of un aseptic perisynthetic fluid collection, while the remaining 5 patients (6%) who developed complications benefited from conservative treatment: 4 patients (3.6%) with infectious complications were treated with intravenous antibiotics. In the 2 patients (2.3%) with mobilization or rupture of synthesis devices, clinical and radiographic monitoring was opted for. 8 patients (10.7%) died: one 48 hours after the surgery, and the other 7 more than one month after the surgery. CONCLUSION Our clinical findings align with to existing scientific literature on periprosthetic fractures (B1 and C according to Vancouver classification). Moreover, good stability has been guaranteed at the radiological follow up by Zimmer Biomet NCB-PP® and INTRAUMA DF distal femur and PFF proximal plates. The locking construct allows for improved stability especially in osteoporotic bone.

Evolution and New Generation of Dual Mobility Cups.

Although total hip arthroplasty (THA) is considered a successful procedure, hip dislocation remains the main cause of early failure. Dual mobility cups (DMCs) have been shown to significantly reduce the dislocation rate in both primary and revision THAs. During the past several decades, DMCs have evolved in design and fixation interface. There have been three generations of DMCs. This article addresses the rationale for a new cementless highly porous titanium DMC to improve component fixation and implant biocompatibility. [Orthopedics. 2023;46(5):e273-e280.].

Modular dual mobility articulation in primary and revision hip arthroplasty: lights and shadows.

PURPOSE: The use of dual mobility cups in total hip arthroplasty has gained popularity in light of the fact it enables to reduce dislocation through increased jumping distance (JD) and impingement-free arc of movement. Modular Dual Mobility Cup (modular DMC) systems have been recently introduced to enable the use of dual mobility cups with standard metal-backed shells. The objective of this study was twofold: calculate the JD for each modular DMC system and conduct a systematic literature review to report clinical outcomes and reasons for failure of this construct. METHODS: The JD was calculated using the Sariali formula: JD = 2Rsin [(π/2 - Ψ - arcsin (offset/R))/2]. A qualitative systematic literature review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search for English and French articles between January 2000 and July 2020 was run on PubMed, EMBASE, Google Scholar, and Scopus with the primary objective of finding articles about modular DMC systems. RESULTS: We identified eight 8 different manufacturers of modular DMC systems and 327 publications on the subject. After screening for duplicates and eligibility, we identified 229 publications: 206 articles were excluded because they contained no reports on modular DMC systems, whereas other three were not included because they focused on biomechanical aspects. Among the 11 included articles, 2 were prospective case series, 9 were retrospective case series. True dislocation occurred in 25 cases (0.9%), and six of them were solved by closed reduction without necessity of revision, while all 5 intraprosthetic dislocations were operated. CONCLUSIONS: Modular DMCs are a valid method to deal with complex THA instability, with good clinical and patient-reported outcomes, low complication rates, and low revision rates at early follow-up. We would advise cautious optimism on the role of modular DMC implants, as it seems safer to use ceramic instead of metallic heads whenever possible to avoid the increase cobalt and chromium trace ion serum levels.

Computer-assisted surgery as indication of choice: total knee arthroplasty in case of retained hardware or extra-articular deformity.

PURPOSE: The use of traditional cutting guides during knee arthroplasty in some cases could be extremely difficult, if not impossible, because of angular deformities, IM sclerosis, long-stemmed hip implants, or hardware within the femoral canal that cannot be removed. In these difficult cases navigation-assisted knee arthroplasty should be considered as an effective and appealing option. METHODS: We present 14 cases in which ideal mechanical and prosthetic alignment was achieved with different image-free, computer-assisted navigation systems, because of an extra-articular deformity (group A, nine patients) or because of a retained implant or hardware (group B, five patients). RESULTS: After a mean follow-up of 28 months (range 12-53 months), the average knee score increased overall from a mean of 33 points (range 12-63) to 78 points (range 63-90). The average functional score improved from a mean of 32 points (range 10-65) to 72 points (range 40-90). The postoperative mechanical axis ranged between 3° of varus and 3° of valgus. There was an implant revision in one patient who had a traumatic rupture of medial collateral ligament, which occurred 27 months after the index procedure. CONCLUSIONS: Based on our results we think that the navigation-assisted technique provides an alternative approach to the traditional instrumentation for treating these difficult patients in an effective and less invasive manner.

Intra-Articular Calcaneal Fractures: Comparison between Mini-Invasive Approach and Kirschner Wires vs. Extensive Approach and Dedicated Plate-A Retrospective Evaluation at Long-Term Follow-Up.

INTRODUCTION: Calcaneal fractures (CF) are the most common tarsal fractures, representing up to 75% of foot fractures and 2% of all fractures. The aim of this retrospective study is to analyze fixation with Kirschner wires through a mini-invasive approach and dedicated plate and screws through an extended approach at long-term follow-up. MATERIALS AND METHODS: Patients were radiographically and clinically evaluated at final follow-up, by using the validated American Orthopedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score for the clinical-functional assessment, the Short-Form 12 (SF-12) for the physical and psychological domain assessment, and the Visual Analog Scale (VAS) for pain. RESULTS: In total, 38 patients (42 CF) met the inclusion criteria and were retrospectively evaluated and divided into two groups (Kirschner group and plate group) consisting of 19 patients each. The overall mean follow-up was 59.4 ± 11.8 months. The average values of the post-operative clinical outcomes of the two groups KG and PG were, respectively, 70.7 ± 11.9 and 70.1 ± 10.9 (AOFAS), 45.7 ± 6.8 and 46.5 ± 10.8 (SF-12 PCS), 54.7 ± 9.9 and 50.9 ± 11.8 (SF-12 MCS) at the final follow-up. CONCLUSIONS: The present study showed that in the cases analyzed, the two surgical approaches used for the treatment of CF achieved comparable clinical outcomes. The only substantial difference found between the two groups of patients was the re-intervention rate that afflicted them.

Italian Consensus Conference on Guidelines for preoperative treatment in acetabular fractures.

Preoperative management of acetabular fracture is a major problem and no consensus has been reached in literature on the optimal treatment of this problem. We present the results of the First Italian Consensus Conference on Acetabular fracture. An extensive review of the literature has been undertaken by the organizing committee and forwarded to the panel. Members were appointed by surgical experience with acetabular fractures. From November 2017 to January 2018, the organizing committee undertook the critical revision and prepared the presentation to the Panel on the day of the Conference. Then 11 recommendations were presented according to the 11 submitted questions. The Panel voted the recommendations after discussion and amendments with the audience. Later on, a second debate took place in September 2018 to reach a unanimous consent. We present results of the following questions: does hip dislocation require reduction? Should hip reduction be performed as soon as possible? In case of unsuccessful reduction of the dislocation after attempts in the emergency department, how should it be treated? If there is any tendency toward renewed dislocation, how should it be treated? Should Computed Tomography (CT) scan be performed before reduction? Should traction be used? How can we treat the pain? Is preoperative ultrasound exam to rule out vein thrombosis always necessary? Is tranexamic acid intravenous (IV) preoperatively recommended? Which antibiotic prophylactic protocols should be used? Is any preoperative heterotopic ossification prophylaxis suggested? In this article we present the indications of the First Italian Consensus Conference: a hip dislocation should be reduced as soon as possible. If unsuccessful, surgeon may repeat the attempts optimizing the technique. Preoperative CT scan is not mandatory before reduction. Skeletal traction is not indicated in most of the acetabular fracture. Standard pain and antibiotic prophylactic protocols for trauma patient should be used. Preoperative ultrasound exam is not recommended in all acetabular fracture. Tranexamic acid should be preoperatively used. There is no indication for preoperative heterotopic ossification.

Combined wear behavior and long-term implant-bone fixation of total knee replacement: a novel in vitro set-up.

The success of a total knee replacement (TKR) strongly depends on the prosthetic design; this includes on one hand the best choice of the bearing materials to minimize wear, on the other hand a good orientation of the prosthetic components with respect to the loading directions. The aim of this study was to investigate the feasibility of a new experimental setup combining two fundamental aspects for the long-term success of knee implants: wear and micromotions. A novel procedure was used to simulate working conditions as close as possible to in vivo ones and to measure implant-bone micromotion, by means of fixing the femoral component of the prosthesis to the distal part of a synthetic femur to be tested through a knee simulator. Gravimetric wear of the tibial specimens was assessed at regular intervals. Implant-bone inducible micromotions and permanent migrations were measured at three locations throughout the test. Wear patterns on tibial specimens were characterized through a standardized protocol based on digital image analysis; fatigue damage in the cement was quantified. Some initial conditioning was noticed both in the wear process and microcracking distribution within the cement mantle. Similarity in wear tracks observed on tibial inserts and other retrieval studies, coupled with clinically consistent migration patterns for TKR, supports the efficacy of the new in vitro method presented.

Comparison between two computer-assisted total knee arthroplasty: gap-balancing versus measured resection technique.

Two surgical strategies are possible in total knee arthroplasty (TKA): a measured resection technique, in which bone landmarks are used to guide resections equal to the distal and posterior thickness of the femoral component, or a gap-balancing approach, in which equal collateral ligament tension in flexion and extension is sought before and as a guide to final bone cuts. In this study performed with computer assisted system, we compared the 2 different methods in 126 patients followed prospectively in order to analyze the effect of both the techniques on joint-line (JL) maintenance, axial limb restoration and components position. The gap technique showed a statistical increase in the post-operative value when compared with the measured resection technique, (P = 0.008). When comparing the two groups regarding to the pre-operative deformity, we have found a statistical difference (P = 0.001) in case of moderate pre-operative deformity (less than 10 degrees), and the measured resection technique showed a slight superiority in preserving a joint line more faithful to the pre-operative. We found an ideal alignment for the mechanical axis (180 degrees ± 3 degrees) (95% of cases). In six cases (5%), the mean post-operative value exceeded (varus or valgus) the ideal value by more than 3 degrees. In the frontal plane, a good alignment was observed for both femoral and tibial components without a significant difference between the two techniques. In the sagittal plane was found more alignment variability due to the different implants used and their ideal starting slope, from 7 degrees to 3 degrees. Finally, the surgeon can use the approach with which he has more confidence; however, as the measured resection technique causes less reduction in the post-operative joint-line position, in case of shortening of patellar tendon or patella infera, this technique is preferable.

Knee joint arthroplasty after tibial osteotomy.

A total of 29 consecutive knee joint arthroplasties in 24 patients who underwent previous high tibial osteotomy (HTO) for medial unicompartment osteoarthritis of the knee and followed up for a mean of 97 months were compared with a control group of 28 patients with 29 primary total knee arthroplasty (TKA) without previous HTO. Results for the osteotomy group were satisfactory in 96.5% of cases. In one patient loosening of the implant occurred after 37 months, which required prosthesis revision. Three patients underwent a further operation of secondary patella resurfacing for patella pain. The group without osteotomy reported a similar percentage of satisfactory results.

Revision of a Monoblock Metal-on-Metal Cup Using a Dual Mobility Component: Is It a Reasonable Option?

Revision of large-diameter, monoblock acetabular components for both hip resurfacing arthroplasty and metal-on-metal (MoM) total hip arthroplasty (THA) is correlated to a high amount of complications. For this reason, performing a limited revision by conversion to a dual mobility (DM) without acetabular component exchange has been proposed in order to limit these complications. Although DM bearing offers an easy solution avoiding the intraoperative and time-associated complications, concern about polyethylene wear and stability remains due to the difference regarding the design, the coverage angle and the clearance of the two implants. In order to evaluate the performance of this new solution with the new material to prevent the possibility of failure it is essential to conduct a review of the literature A qualitative systematic review of the literature has been conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search of PubMed, EMBASE, Google Scholar, and Scopus for English and French articles between January 2000 and October 2019 was performed, with the primary objective of finding articles about dual mobility bearing coupling with large metal-on-metal cup in the case of hip revision procedure. Various combinations of the key words were used in the search strategy. Thirteen articles with DM bearing mated with MoM cup were analyzed. Of the 130 hip revisions selected, with a follow-up from 6 to 53 months, there were a total of 14 with complications (10.77%): four true dislocations (3.08%); six intra-prosthetic dislocations (IPD, 4.6%), two of which presented plastic deformation and polyethylene wear; four other complications (3.08%), included a cup osteolysis, a clicking noise, a superficial infection and a periprosthetic fracture. All the mentioned true dislocations occurred during the first month while IPDs appeared during the first two years from the index revision. In conclusion, according to the literature analyzed, we can stress that the concerns and doubts about mating a DM bearing with large MoM cup cannot be dissolved. It has been pointed out that a DM bearing is not designed for a MoM cup; it is not mechanically tested on MoM cups, which presents different clearance and coverage angles. Predictable complications may occur, such as IPD, polyethylene wear and true dislocation. These complications have been reported at an even higher rate than they were in the eighties, when the first generation of DM implants were of a lower quality of polyethylene and the characteristic of the design was less optimal than modern ones.

Tendon Extracellular Matrix Remodeling and Defective Cell Polarization in the Presence of Collagen VI Mutations.

Mutations in collagen VI genes cause two major clinical myopathies, Bethlem myopathy (BM) and Ullrich congenital muscular dystrophy (UCMD), and the rarer myosclerosis myopathy. In addition to congenital muscle weakness, patients affected by collagen VI-related myopathies show axial and proximal joint contractures, and distal joint hypermobility, which suggest the involvement of tendon function. To gain further insight into the role of collagen VI in human tendon structure and function, we performed ultrastructural, biochemical, and RT-PCR analysis on tendon biopsies and on cell cultures derived from two patients affected with BM and UCMD. In vitro studies revealed striking alterations in the collagen VI network, associated with disruption of the collagen VI-NG2 (Collagen VI-neural/glial antigen 2) axis and defects in cell polarization and migration. The organization of extracellular matrix (ECM) components, as regards collagens I and XII, was also affected, along with an increase in the active form of metalloproteinase 2 (MMP2). In agreement with the in vitro alterations, tendon biopsies from collagen VI-related myopathy patients displayed striking changes in collagen fibril morphology and cell death. These data point to a critical role of collagen VI in tendon matrix organization and cell behavior. The remodeling of the tendon matrix may contribute to the muscle dysfunction observed in BM and UCMD patients.

Pre-operative diagnosis of infection in total knee arthroplasty: an algorithm.

The aim of our study was to construct an algorithm for the pre-operative diagnosis of infection in total knee arthroplasty. We analyzed the currently used parameters in a consecutive series of 31 patients with failed implants. An outcome of at least 2 years was prospectively considered to validate our algorithm. Patient history, imaging, laboratory studies, histology, pre- and intra-operative cultures were considered. The optimal cutoffs of the inflammation tests for diagnosing infection were determined by constructing the receiver operating-characteristic curves. Sensitivity, specificity and accuracy of these tests as infection markers were determined. The combination of at least two tests with values higher than the cutoffs is reliable for predicting the infection. Scintigraphy, needle-aspirate cell count and culture can integrate the pre-operative evaluation. Doubtful cases can be clarified by microbiological and histological analyses. As a result an algorithm helpful to identify the cause of loosening has been developed. In our opinion, adherence to this algorithm could contribute to preoperatively define a rational surgical and antibiotic treatment strategy.