Which design tolerates rotational mismatch better in unicompartmental knee arthroplasty: fixed or mobile bearing?

Unicompartmental knee arthroplasty is an effective method for the treatment of medial compartment osteoarthritis. However, appropriate surgical tech- nique and optimum implant positioning are crucial for a satisfactory outcome. This study aimed to demonstrate the relation between the clinical scores and the alignment of the components in UKA. A total of 182 patients with medial compartment osteoarthritis and treated by UKA between January 2012 and January 2017 were enrolled in this study. Computed tomography (CT) was used to measure the rotation of components. Patients were divided into two groups according to the insert design. These groups were divided into three subgroups according to the angle of the tibia relative to the femur (TFRA) (A): TFRA 0° to 5° either internal or external rotation; (B): TFRA >5° internal rotation, and (C): TFRA >5° external rotation. There was no significant difference between the groups in terms of age, body mass index (BMI) and follow-up period. KSS scores increased as the tibial component rotation (TCR) external rotation increased, but there was no correlation for WOMAC score. (P: 0,039 r: 0,207; P:0,347 r:0,095, respectively) Post-operative KSS and WOMAC scores decreased as TFRA external rotation was increased. (p: 0,001; p:0,001, respectively) No correlation has been observed between femoral component rotation (FCR) internal rotation and post-operative KSS and WOMAC scores. (p: 0,261; p: 0,502, respectively) Any mismatch between the components is better tolerated by mobile-bearing designs compared to fixed-bearing designs. Orthopedic surgeons should take care of rotational mismatch of components, not only the axial alignment of the components.

Effects of hypothermia on skeletal ischemia reperfusion injury in rats.

OBJECTIVE: The aim of this study was to investigate the effect of hypothermia (H) on skeletal ischemia-reperfusion (IR) injury in rats by measuring malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), nitric oxide (NO), and interleukin-1 beta (IL-1ß) in muscle, and measureing immunohistochemical-inducible nitric oxide synthase (iNOS) staining of skeletal muscle. MATERIALS AND METHODS: Eighteen Wistar Albino rats were divided randomly into three groups (sham, IR, hypothermia) (n=6). The sham group had all procedures without the IR period. The lower right extremity of rats in the IR and hypothermia groups was subjected to 2 hours of ischemia and 22 hours of reperfusion by applying a clamp on the common iliac artery and a rubber-band at the level of the lesser trochanter under general anesthesia. Rats in the hypothermia group underwent 4 hours of hypothermia during the first four hours of reperfusion in addition to a 2-hour ischemia and 22-hour reperfusion period. All rats were sacrificed at end of the IR period using a high dose of anesthesia. The tibialis anterior muscles were preserved. Immunohistochemical iNOS staining was performed, and MDA, SOD, GSH-Px, NO, and IL-1ß were measured in the muscle. RESULTS: The level of MDA, NO, and IL-1ß in muscle was increased in the IR group compared with that in the sham group, but these parameters were decreased in the hypothermia group compared with the IR group. The activities of SOD and GSH-Px in muscle were decreased in the IR group; however, these parameters were increased in the hypothermia group. The score and intensity of iNOS staining of skeletal muscle was dens in IR group, mild in hypothermia group, and weak in sham group. CONCLUSION: The present study has shown that hypothermia reduced IR injury in the skeletal muscle by decreasing the levels of MDA, NO, and IL-1ß, and increasing the activities of SOD and GSH-Px. In addition, hypothermia attenuated the score and intensity of iNOS staining.