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This article presents a series of case studies on the rare complication of meniscal bearing fractures after unicompartmental knee arthroplasty (UKA). The authors describe the symptoms, radiographic findings, and surgical interventions of six patients who experienced this complication. They suggest that a 3 mm bearing thickness may be a risk factor for fracture, but the role of BMI is inconclusive. The authors emphasize the importance of considering meniscal bearing fracture as a potential diagnosis in patients with sudden symptoms after UKA and recommend a systematic diagnostic approach to avoid overlooking this complication. [Extracted from the article]

The poor results of total ankle replacement have been attributed to the inability of designers to restore adequately the critical mutual function of the ligaments and the articular surfaces. The purpose of this study was to design sagittal shapes of the articular surfaces for a new ankle prosthesis to be compatible with the geometry of the retained ligamentous structures. Several ligament-compatible pairs of articular surfaces were tested using a computerised version of a four-bar linkage model. The kinematics of the ankle when replaced by non-conforming two-component and by fully conforming three-component designs with either flat, concave or convex tibial surfaces were assessed by the model. A ligament-compatible convex-tibia fully-congruent three-component prosthesis showed the best features. The three-component prosthesis allows complete congruence over the entire range of flexion. A convex shape for the tibial arc was preferred because of the better degree of entrapment of the meniscal bearing. A 5 cm convex-tibia arc radius gave 2 mm entrapment together with 9.8 mm of tibial bone cut. Ligament elongation imposed by full congruence of the articular surfaces was less than 0.03% of the original length. The original patterns of joint kinematics and ligament tensioning are closely restored in the joint replaced by the proposed prosthesis. [ABSTRACT FROM AUTHOR]