[Treatment of chondroblastoma of the humeral head : A tumour- and shoulder-orthopaedic challenge]. / Die Behandlung des Chondroblastoms im Humeruskopf : Eine tumor- und schulterorthopädische Herausforderung.

We present the case of a 22-year-old female patient with chondroblastoma in the right humeral head. To allow a gentle and anatomic resurfacing of the humeral joint surface and to avoid total joint arthroplasty in our young patient with high functional requirements, we implanted a HemiCAP® after intralesional curettage of the chondroblastoma. Our patient's excellent short-term functional outcome shows that our approach can be considered a very good therapeutic option.

Glenoid Concavity Affects Anterior Shoulder Stability in an Active-Assisted Biomechanical Model.

Background: The treatment of bony glenoid defects after anteroinferior shoulder dislocation currently depends on the amount of glenoid bone loss (GBL). Recent studies have described the glenoid concavity as an essential factor for glenohumeral stability. The role of glenoid concavity in the presence of soft tissue and muscle forces is still unknown. Hypothesis: Glenoid concavity would have a major impact on glenohumeral stability in an active-assisted biomechanical model including soft tissue and the rotator cuff's compression forces. Study Design: Controlled laboratory study. Methods: In 8 human shoulder specimens, individual coordinate systems were calculated based on anatomic landmarks. The glenoid concavity was measured biomechanically and based on computed tomography. Static load was applied to the rotator cuff tendons and the deltoid muscle. In a robotic test setup, anteriorly directed force was applied to the humeral head until translation of 5 mm (Nant) was achieved. Nant was used as a parameter indicating shoulder stability. This was performed in the following testing stages: (1) intact joint, (2) labral lesion, (3) 10% GBL, and (4) 20% GBL. The 8 specimens were divided equally into 2 subgroups (low concavity [LC] versus high concavity [HC]), with 4 specimens each, according to the previously measured concavity. Results: Anterior glenohumeral stability was highly correlated with the native glenoid concavity (R 2 = 0.8). In the testing stages 1 to 3, we found a significantly higher mean stability in the HC subgroup compared with the LC subgroup (P≤ .0142). The HC subgroup still showed higher absolute Nant values with 20% GBL; however, there was no significant difference from the LC subgroup. The loss of stability in 20% GBL was correlated with the initial concavity (R 2 = 0.86). Thus, a higher loss of Nant in the HC subgroup was observed (P = .0049). Conclusion: In an active-assisted model with intact soft tissue surrounding and muscular compression forces, the glenoid concavity correlates with shoulder stability. In bony defects, loss of concavity is an essential factor causing instability. Due to their significantly higher native stability, glenoids with HC can tolerate a higher amount of GBL. Clinical Relevance: Glenoid concavity should be considered in an individualized treatment of bony glenoid defects. Further studies are required to establish reference values and develop therapeutic algorithms.

Erratum to 'Fungal Periprosthetic Knee Joint Infection in a Patient With Metamizole-Induced Agranulocytosis' [Arthroplasty Today 6 (2020) 726-730].

[This corrects the article DOI: 10.1016/j.artd.2020.07.040.].

Fungal Periprosthetic Knee Joint Infection in a Patient with Metamizole-Induced Agranulocytosis.

We present the case of a 55-year-old female patient with metamizole-induced agranulocytosis after total knee arthroplasty, leading to septic periprosthetic joint infections (PJIs). Owing to metamizole-induced agranulocytosis, the synovial leukocyte count was negative. Here, we discuss the diagnostic challenges evolving from sepsis and neutropenia in patients with suspected PJIs. We suggest an urgent surgical approach, mainly focusing on the clinical presentation preoperatively. Later, our patient developed candidemia and periprosthetic tissue samples were positive for Candida albicans. For fungal PJIs, long-term follow-up studies are lacking and therapeutic recommendations differ. Here, we present our therapeutic approach, including staged revision and 12 weeks of systemic antifungal therapy, and discuss recent findings regarding the therapy of fungal PJIs.