How to choose kinematic or mechanical alignment individually according to preoperative characteristics of patients?

BACKGROUND: Making decisions in alignment techniques in total knee arthroplasty (TKA) remains controversial. This study aims to identify the potential patients who were suitable for the kinematic (KA) or mechanical alignment (MA). METHODS: We reviewed 296 consecutive patients (296 TKAs, including 114 KA-TKAs and 182 MA-TKAs) who underwent unilateral TKA using a computer-assisted navigation from 2016 to 2018 in our prospectively maintained database. The minimum followup was 1 year. Clinical outcomes including the range of motion (ROM) and knee society score (KSS) were compared between KA-TKAs and MA-TKAs. Multiple regression models were used to evaluate the relationship between alignment techniques and KSS at the 1-year followup. Interaction and stratified analyses were conducted according to gender, age, body mass index (BMI), preoperative hip-knee-ankle (HKA) angle, ROM and KSS. RESULTS: ROM and KSS at the 1-year followup didn't differ between MA-TKAs and KA-TKAs (all p > 0.05). Alignment techniques did not associate with postoperative ROM (Adjusted ß = 0.4, 95% confidence interval [CI]: - 0.3, 1.6; p = 0.752) or 1-year KSS (Adjusted ß = 2.2, 95%CI: - 0.7, 5.6; p = 0.107). Patients with a BMI more than 30 kg/m^2 achieved better 1-year KSS when using MA than KA (p for interaction< 0.05). Additionally, patients with preoperative HKA angle more than 10 degrees varus benefited more from KA than MA (p for interaction< 0.05). CONCLUSIONS: Patients with severe varus deformity may be suitable for the KA technique, whereas MA should be used in obese patients.

[Experimental study of the effects of time-phased cryopreservation and resuscitation on biological characters of osteoblasts].

This is an in vitro study to explore the effects of cryopreservation and resuscitation on the biological characteristics of osteoblasts at different times. Osteoblasts taken from the crania of newly born SD rats were cultured. Comparative studies were made on the cells' proliferation, the activity of alkaline phosphatase (ALP), and the number of live cells among fresh cultured osteoblasts and cells after the inception of cryopreservation and resuscitation at time-periods of one, three, six months respectively. The results showed that there were no significant differences among four groups in cell proliferation and in activity of ALP (P > 0.05). Yet, after cryopreservation and resuscitation, there were significant differences between the six-month group and the other three groups (P < 0.05). The results also showed, after cryopreservation and resuscitation, there were no significant differences between the control group and the one-month and three-month groups, respectively (P > 0.05). These findings indicated that the live cells might decrease in number after the osteoblasts were cryopreserved for too long a period, but after cryopreservation and resuscitation, the cells still retained the original biological characteristics of osteoblasts.