Osteochondritis dissecans of the knee is a disease that typically affects skeletally immature patients. Clinically manifested with knee pain, limping, and joint disfunction, this condition has remained misunderstood and undervalued for a long period. Although being a rare condition, its awareness is of utmost clinical interest because of the possible severe consequences it can bring when misrecognized or inadequately treated. Its etiology remains unclear and is still debated. Many theories have been proposed, including inflammation, local ischemia, subchondral ossification abnormalities, genetic factors, and repetitive mechanical microtrauma, with a likely interplay of the same. This review article aims to deliver and discuss current and up-to-date concepts on epidemiology, etiology, and natural history of this pediatric condition. Level of evidence: level V.

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Purpose To compare the rate of return to sports and body mass index (BMI) reduction in patients who underwent surgery for unicompartmental knee arthroplasty (UKA) with either Cobalt-Chromium (CoCr) alloy UKA or with hypoallergenic UKA, stratiied by age, gender and BMI. Methods Two consecutive cohorts of patients with a total of 172 UKA and a minimum 2-year follow-up period were prospectively included in this comparative study. The irst cohort consisted of 136 consecutive series of standard Cobalt-Chromium (CoCr Group). The second cohort consisted of 36 consecutive mobile-bearing hypoallergenic Titanium Niobium Nitride UKA, (TiNbN Group). The clinical evaluation was based on the University of California, Los Angeles (UCLA) activity scores and the High-Activity Arthroplasty Score (HAAS) evaluated on the day before surgery (T 0 ) and after a minimum follow-up of 12 months (T 1 ) and 24 months (T 2 ). Radiographic evaluation performed at T 2 included the femoral component position in varus/valgus, the tibial component in varus/valgus and the anteroposterior slope. ResultsNo statistical diferences were found between the groups at each follow-up, as shown by the UCLA and HAAS score (n.s.). Both groups showed a statistically signiicant improvement (p < 0.05) at each follow-up. . Both groups showed a statistically signiicant BMI reduction between T 0 and T 2 (p < 0.05). Radiographic analysis revealed no statistical diferences between the two groups in terms of the three measures after the inal follow-up (n.s.). All the subgroups showed a signiicant (p < 0.05) rate of return to sport if compared with the preoperative value (T 2 versus T 0 ), except for male in TiNbN group. Conclusions Both TiNbN and CoCr medial mobile-bearing UKA enabled patients to return to sports after the inal follow-up, regardless of age, BMI, gender and metal sensitivity. These indings inform shared decision making and can help to manage patient expectations after surgery, in particular, in active patients with an overt metal allergy, a speciic hypoallergenic implant should be considered the gold standard implant in partial knee replacement surgery. Level of evidence Cohort Study, Level III. Registration: researchregistry6250-www.resea rchre gistr y.com.

Periprosthetic joint infection (PJI) is among the most feared orthopedic complications. Critical questions are whether the infection is completely resolved before reimplantation and what the clinical significance of positive culture is at reimplantation. The aim of this study was to determine whether a correlation exits between culture results at reimplantation after spacer insertion for hip and knee PJI and treatment failure rate. The data of 84 patients who underwent two-stage exchange arthroplasty for hip or knee PJI were reviewed and the results of intraoperative culture at reimplantation were analyzed quantitatively and qualitatively. Correlations were sought between these patterns and treatment outcome. Our data indicate no evidence for a correlation between positive culture at reimplantation and greater risk of treatment failure. Nonetheless, we noted a higher, albeit statistically not significant rate of treatment failure in patients with at least two samples testing positive. The role of microbiology at reimplantation remains unclear, but a positive culture might signal increased risk for subsequent implant failure. Further studies are needed to elucidate the implications of this finding.

The aim of this systematic review is to assess the role of the prophylactic fixation of contralateral unaffected hip in unilateral slipped capital femoral epiphysis (SCFE) in children, focusing on the possible complications of this surgical procedure. A systematic review of medical literature was conducted, according to the Preferred Reporting Items for Systematic review and Meta-Analysis (PRISMA) statement, to analyse the complications of prophylactic contralateral hip fixation in unilateral paediatric SCFE. We registered the complications reported in the included studies, scoring their severity according to the orthopaedic adaptation of Clavien–Dindo classification. From 1695 studies primarily identified, 14 studies were finally included: 1 prospective cohort study, 4 retrospective case-control studies and 9 retrospective case series, with a total of 811 children diagnosed with unilateral SCFE and treated on the unaffected contralateral hip. Grade IV complications were very rare (0.37%), while the rate of grade III events was 8%. No death was recorded. The most frequent complication was unplanned further surgery (6.29%) that was an epiphyseal refixation, owing to the physiologic growth of the proximal femur, in 42 cases. Cannulated screws fixation showed to have a lower major complication rate than pinning with K-wires, 5.37% vs 17.95%. The prophylactic fixation of contralateral unaffected hip in paediatric unilateral SCFE is a safe procedure. Although a benefit-cost analysis on this topic has not been published yet, considering the low rate of complications, prophylactic hip fixation is a viable option for patients presenting with unilateral SCFE, to prevent the occurrence of severe hip deformity and avoid future invasive surgeries.