This study assessed the influence of a 10‐day hypoxic bed rest on cartilage biomarkers and subchondral bone density across the patellofemoral joint (PFJ). Within clinical settings hypoxic tissue may arise in several types of disorders. Furthermore, a hypoxic environment is being considered for space flight habitats in the near future. Female participants (N = 12) participated in this study comprising three 10‐day interventions: hypoxic ambulation (HAMB), normoxic bed rest (NBR), and hypoxic bed rest (HBR). Venous samples were collected prior to (day −2: Pre) and during the intervention (days 2 and 5), immediately before reambulation (D11) and 24 hr post intervention (R1). Blood samples were analyzed for: aggrecan, hyaluronan, Type IIA procollagen amino terminal propeptide (PIIANP), and cartilage oligomeric matrix protein (COMP). Total bone mineral density (BMD) in eight regions (2 mm × 10 mm) across the PFJ was determined. The three interventions (HAMB, HBR, and NBR) did not induce any significant changes in the cartilage biomarkers of hyaluronan or PIIANP. Aggrecan increased during the HAMB trial to 2.02 fold the Pre value. COMP decreased significantly in both NBR & HBR compared to HAMB on D5. There were significant differences in BMD measured across the PFJ from cortical patellar bone (735 to 800 mg/cm³) to femur trabecular (195 to 226 mg/cm³). However, there were no significant changes in BMD from Pre to Post bed rest. These results indicate that there were no significant detectable effects of inactivity/unloading on subchondral bone density. The biomarker of cartilage, COMP, decreased on D5, whereas the addition of hypoxia to bed rest had no effect, it appears that hypoxia in combination with ambulation counteracted this decrease.

Background: To investigate the influence of sport-specific activities on coronal axial alignment of the lower limbs in adolescent football and ice hockey players. Methods: This cross-sectional study targeted healthy adolescent male football and ice hockey players with at least 3 years of sports participation. 90 football and 38 ice hockey players aged 12–16 years were divided into five age-matched subgroups. Coronal alignment of the lower limbs was determined by measuring the players' intercondylar or intermalleolar (ICD-IMD) distance with a custom-made calliper. In addition, their sports history was recorded. An age-matched comparison between the two sports groups was performed using the two-way model ANOVA and a multiple regression model for ICD-IMD was constructed. Results were additionally compared with age-matched data from the general population published in recent literature. Results: A statistically significant increase in ICD-IMD values (p < 0.05) was found between 12 (football 0 mm; ice hockey − 64 mm) and 16 years (football 340 mm; ice hockey 310 mm) in both sports groups. Results of regression analysis of pooled group data showed that ICD-IMD has low positive correlation (r = 0.407; r² = 0.168; p < 0.05) with time of participation in sport, but no association with age of athletes at the start of their sport participation (r = − 0.018; r² = 0.000; p > 0.05). There were no statistically significant differences between the two groups at any time point. Both sports groups showed a significant increase in ICD-IMD values (mean 198 mm) after the age of 14 compared to the general population. Conclusions: Participation in football and ice hockey is associated with a similar increase in ICD-IMD in the adolescent years in male athletes. The observed increase was higher in both groups of athletes than in their peers who do not regularly participate in sports. Level of Evidence: Level 4 (case series).

Objective: To compare patient-reported outcomes and reintervention rates after open vs arthroscopic fusion of the ankle (TT—tibiotalar) or subtalar (ST) joint over a 10-year period in a cohort of patients from a single center. Methods: In total, 129 patients (142 joints) underwent surgery for isolated TT or ST osteoarthritis between 2010 and 2020: 40 TT fusions (11 arthroscopic, 29 open) and 102 ST fusions (25 arthroscopic, 77 open). The course of treatment was followed clinically using patient-reported outcome measures (PROMs) for ankle function: Foot and Ankle Outcome Score—FAOS, general quality of life (European Quality of Life in Five Dimensions 3-level time-trade-off—EQ-5D 3L-TTO) and activity level (Tegner Activity Scale—TAS), and by tracking revision procedures. Results: The median follow-up time was 8 (3–13) years. The mean age at the time of surgery was 52 (14) years. Most subjective scores showed significant improvement; cumulative FAOS improved from 41 to 57 in the TT group and from 41 to 67 in the ST group and EQ-5D from 0.40 to 0.55 (TT group) and from 0.38 to 0.60 (ST group), while TAS remained at 2. The ST fusion patients had better subjective outcomes than TT fusion patients. There were no significant differences in PROMs between arthroscopic and open procedures. Older age and preoperative FAOS pain were found to be negative predictors for the postoperative FAOS subscales. Overall, there was an 18% revision rate: 17 non-unions and 8 infections. In addition, 20 hardware removals were performed. Conclusion: Isolated TT or ST fusions performed open or arthroscopically were safe and significantly improved function and quality of life and reduced joint-related pain but did not increase patients’ activity levels. Patients with ST fusion had a better subjective outcome. Older age and lower preoperative FAOS pain were associated with a worse postoperative subjective outcome. Level of Evidence: Level III

Background: We present prospective short-term results of a limited patient series treated with two innovative partial ankle arthroplasties: talar dome resurfacing for mild-to-moderate ankle osteoarthritis and talar shoulder hemiarthroplasty for chronic medial osteochondral lesions of the talus. Methods: Eleven patients underwent talus resurfacing and six patients had talar hemiarthroplasty. The outcome was followed by patient-reported measures and by pursuing serious adverse events or implant failures over a 2-year period. Progression of ankle osteoarthritis, peri-implant bone changes, and implant migration were followed radiographically. Results: Active dorsiflexion increased from 3° to 10° in resurfacing and from 15° to 22° in hemiarthroplasty. Patient-reported ankle function, quality of life, and activity level tended to improve only slightly after resurfacing (cumulative Foot and Ankle Outcome Score, from 41 to 42; Foot and Ankle Ability Measures for daily activities [FAAM-ADL], from 43 to 46; EQ-5D-3L time trade-off, from 0.38 to 0.39; Tegner activity scale score, from 1.6 to 2.0) but moderately after hemiarthroplasty (cumulative Foot and Ankle Outcome Score, from 58 to 68; FAAM-ADL, from 37 to 71; EQ-5D-3L time trade-off, from 0.53 to 0.72; Tegner activity scale score, from 3.1 to 3.1). No implant-related radiographic changes, implant failures, or implant-related revision surgeries were recorded. Conclusions: Based on a small and heterogeneous prospective case series, both partial ankle implants investigated were safe and stable over 2-year follow-up, without any radiographic osteoarthritis progression of the remaining joint. However, patient-reported ankle function, quality of life, and activity level showed a tendency toward only minor improvement after resurfacing but a moderate increase after hemiarthroplasty.

Patellofemoral instability (PFI) can significantly hinder and limit knee function. A widely accepted treatment of PFI is the medial patellofemoral ligament reconstruction (MPFLR), with or without additional procedures. This study aimed to evaluate postoperative functional outcomes in patients undergoing MPFLR by comparing the operated knee to the contralateral, asymptomatic knee using validated patient-reported outcome measures (PROMs). From a prospective database, 71 adult patients (18 years or older) treated for chronic unilateral PFI between 2012 and 2019 were enrolled in a retrospective cohort study. Patients undergoing MPFLR, either in isolation or with TTT, with an asymptomatic contralateral knee were included. Pre- and postoperative comparisons of Knee Injury and Osteoarthritis Outcome Score (KOOS), Tegner Activity Scale, and EQ-5D-3L were conducted. Statistical significance was set at p < 0.05. Seventy-one patients were included; median follow-up was 3.8 years. Postoperatively, significant improvements were observed in all KOOS subscales (p < 0.001), EQ-5D-3L-TTO (Δ0.11, p = 0.002), and EQ-5D-VAS (Δ13, p < 0.000), alongside increased Tegner Activity Scale scores (Δ1, p = 0.002). Despite these gains, operated knees demonstrated persistent functional deficits compared to contralateral asymptomatic knees across all KOOS subscales (p < 0.001). EQ-5D-3L-TTO showed significant inter-limb differences; small nonsignificant differences were noticed in the EQ-5D-VAS and Tegner Activity Scale score. MPFLR significantly improves knee function, pain, and quality of life, yet does not fully restore function to the level of the asymptomatic contralateral knee. Persistent deficits highlight the need for further refinement in surgical techniques to optimize long-term outcomes. level III.