Purpose: There is limited comparative evidence on patient outcomes following cartilage repair in various knee compartments. The aim of this study was to compare clinical and imaging outcomes after treating cartilage defects in femoral condyles and trochlea with either an aragonite-based scaffold or surgical standard of care (SSoC, i.e., debridement/microfractures) in a large multicentre randomized controlled trial. Methods: 247 patients with up to three knee joint surface lesions (ICRS grade IIIa or above) in the femoral condyles, trochlea or both (“mixed”), were enrolled and randomized to surgery with either a cell-free aragonite scaffold or SSoC. Patients were followed for up to 48 months by analysing subjective scores (KOOS and IKDC), radiological outcomes (defect filling on MRI), as well as treatment failure rates and adverse events. A differential analysis of outcomes for condylar, trochlear and mixed lesions was performed. Results: The scaffold group significantly outperformed the SSoC group regardless of lesion location with statistically significantly better KOOS Overall scores at 24 months (all p ≤ 0.0009) and 48 months (all p ≤ 0.02). Similar results were observed for KOOS subscales and IKDC scores. For KOOS responder rates, superiority of the implant group was demonstrated at 24, 36, and 48 months (all p ≤ 0.004). Higher defect filling on MRI for implants was observed for all locations. Lower treatment failure rates for the implant were observed in condylar and mixed lesions. Conclusion: The aragonite-based scaffold was safe and effective regardless of the defect location, providing superior clinical and radiological outcomes compared to SSoC up to four years follow-up. Level of evidence: I – Randomized controlled trial.

Purpose: Growing interest surrounds the role of human gut microbiome in the development of degenerative pathologies such as osteoarthritis (OA), but microbes have recently been detected also in other sites previously considered to be sterile. Evidence emerged suggesting that even native and osteoarthritic knee joints may host several microbial species possibly involved in the osteoarthritic degeneration. This is the first systematic review critically collecting all the available evidence on the existence and composition of knee intra-articular microbiome. Methods: A systematic research on the PubMed, Cochrane and Google Scholar databases was performed. Human clinical studies investigating the presence of intra-articular microbiome in native osteoarthritic knee joints with next-generation sequencing techniques were collected. Results: A total of eight studies were included reporting data on 255 knees. All the included studies reported evidence supporting the existence of an intra-articular microbiome in native knee joints, with detection rates varying from 5.8% to 100%. Bacteria from the Proteobacteria phylum were found to be among the most identified followed by the Actinobacteria, Firmicutes, Fusobacteria, and Bacteroideta phyla. Proteobacteria phylum were also found to be more common in osteoarthritic knees when compared to healthy joints. Furthermore, several pathways correlating those microbes to knee OA progression have been suggested and summarized in this review. Conclusions: Evidence collected in this systematic review suggests that the native knee joint, previously presumed to be a sterile environment, hosts a peculiar intra-articular microbiome with a unique composition. Furthermore, its alteration may have a link with the progression of knee osteoarthritis.

Meniscal extrusion (ME), defined as the radial displacement of the meniscal body outside the margins of the tibial plateau, has been seen as an independent and relevant predictor of intra‐articular knee degeneration. Nonetheless, available classifications for ME are exclusively quantitative assessments not considering the context in which extrusion is identified. Indeed, ME can be the result of several different conditions spanning from acute tears to chronic degeneration and its definition cannot be only dependent on the numeric calculation of the radial displacement of the meniscal body. Furthermore, growing evidence supports the existence of a paraphysiological ME resulting from joint loading, limb malalignment, anatomical abnormalities of the meniscal attachments to the femur and tibia or a nonpathological finding after meniscal allograft transplantation. It is therefore clear that an exclusively quantitative assessment of ME cannot be sufficient since this condition can develop in such different clinical scenarios. For this reason, a novel qualitative classification for ME is proposed, differentiating between three distinct conditions: a paraphysiological ME, a pathological ME and ME related to degenerative conditions. Furthermore, a comprehensive review of the present literature has been conducted to report the most relevant and updated evidence on the topic highlighting the difference in the clinical management of each different category.Level of Evidence: Not applicable.

The burden of osteoarthritis (OA) is around 300 million people affected worldwide, with the hip representing a commonly affected joint. Total hip arthroplasty (THA) has been used with notable success as a definitive treatment to improve pain and function in hip OA patients. The recent advent of new technologies, such as 3D printing, has pushed the application of these new concepts toward applications for the well-known THA. Currently, the evidence on the use of 3D printing to aid complex primary THA cases is still scarce. Methods: An extensive literature review was conducted to retrieve all articles centered on the use of 3D printing in the setting of primary THA. Results: A total of seven studies were included in the present systematic review. Four studies investigated the use of 3D-printed surgical guides to be used during surgery. The remaining three studies investigated the benefit of the use of 3D-printed templates of the pelvis to simulate the surgery. Conclusions: The use of 3D printing could be a promising aid to solve difficult primary total hip arthroplasty cases. However, the general enthusiasm in the field is not supported by high-quality studies, hence preventing us from currently recommending its application in everyday practice.