Background: Tibial fracture after cementless Oxford unicompartmental knee arthroplasty (OUKA) is a rare but serious complication. It is reported more frequently in Asian countries. The aim of this retrospective study was to assess the morphological characteristics of the tibia by using a simple novel measurement method in patients with tibial fractures after OUKA. Methods: Six knees (all women) with tibial fractures after cementless OUKA (fracture group) and 150 knees without an obvious complication after cementless OUKA (control group) were examined retrospectively at our institution between January 2016 and April 2017. We drew a medial eminence line (ME line) defined as a line extending from the tip of the medial intercondylar eminence parallel to the tibial axis. The ME line was classified into two types (intramedullary type [type I] and extramedullary type [type E]), and the proportion of each type was compared between fracture patients and controls. Results: In the fracture group, there were four (66.7%) type E cases and two (33.3%) type I cases; in the control group, there were 18 (12%) type E cases and 132 (88%) type I cases. Fisher exact tests showed that the proportion of type E was higher in the fracture group than in the control group (p < 0.01). Conclusions Measurement of the ME line can be recommended as a useful method to assess the risk of postoperative fracture after cementless OUKA.

A 53-year-old woman with rheumatoid arthritis had been suffering from right thumb deformity for a couple of months. Due to this, she was unable to perform the pinch movement. There were surgical options to treat the deformity, but the patient declined surgery. We therefore surmised whether we could correct the deformity with a splint. In 2012, we then proposed the use of a finger splint. The patient's finger function improved, and as of 2021, she was still using the finger splint without any problems. Thus, it is recommended to use a finger splint for thumb deformity because it is easier and less invasive than surgery.

A 53-year-old woman with rheumatoid arthritis had been suffering from right thumb deformity for a couple of months. Due to this, she was unable to perform the pinch movement. There were surgical options to treat the deformity, but the patient declined surgery. We therefore surmised whether we could correct the deformity with a splint. In 2012, we then proposed the use of a finger splint. The patient's finger function improved, and as of 2021, she was still using the finger splint without any problems. Thus, it is recommended to use a finger splint for thumb deformity because it is easier and less invasive than surgery.