ABSTRACT
BACKGROUND: Although mechanical alignment technique ensures the long-term survival rate of knee arthrosis, some patients are still not satisfied with the effect of total knee arthroplasty and the function of knee joint after operation. OBJECTIVE: Meta-analysis was used to evaluate the effect of kinematic alignment technique and mechanical alignment technique in the guidance of total knee arthroplasty. METHODS: The literature of clinical controlled study of kinematic alignment and mechanical alignment in the guidance of total knee arthroplasty published from the date of establishment to July 2019 was searched in Chinese Biomedical Literature Database, Wanfang data, CNKI, VIP data, PubMed, Cochrane Library, and Embase. The literature was screened, and evaluated; data were extracted. Review Manager 5.3 software was used for statistical analysis. RESULTS AND CONCLUSION: (1) A total of 945 cases were included in 12 articles, including 470 cases in kinematic alignment group and 475 cases in mechanical alignment group. (2) The results of meta-analysis showed that the operation time was shorter in the kinematic alignment group than in the mechanical alignment group [MD=-15.44, 95%C/(-27.16, -3.71)]. Western Ontario and McMaster University Osteoarthritis Index was better in the kinematic alignment group than in the mechanical alignment group [MD=-8.40, 95%C/(-15.39, -1.40)]. Oxford knee score was better in the kinematic alignment group than in the mechanical alignment group [M7=4.72, 95%C/(0.24, 9.21)]. Distal angle of mechanical lateral femur and proximal angle of mechanical medial tibia were significantly larger in the mechanical alignment group than in the kinematic alignment group (all P 0.05). (4) The function of knee joint after kinematic alignment for guiding total knee arthroplasty was better than that in mechanical alignment group. However, the imaging and perioperative results were similar, and the incidence of complications was not increased after operation. It is suggested that kinematic alignment may be a lower extremity force alignment method to guide total knee arthroplasty.
ABSTRACT
Kinematically aligned total knee arthroplasty (TKA) is a new alignment technique. Kinematic alignment corrects arthritic deformity to the patient's constitutional alignment in order to position the femoral and tibial components, as well as to restore the knee's natural tibial-femoral articular surface, alignment, and natural laxity. Kinematic knee motion moves around a single flexion-extension axis of the distal femur, passing through the center of cylindrically shaped posterior femoral condyles. Since it can be difficult to locate cylindrical axis with conventional instrument, patient-specific instrument (PSI) is used to align the kinematic axes. PSI was recently introduced as a new technology with the goal of improving the accuracy of operative technique, avoiding practical issues related to the complexity of navigation and robotic system, such as the costs and higher number of personnel required. There are several limitations to implement the kinematically aligned TKA with the implant for mechanical alignment. Therefore, it is important to design an implant with the optimal shape for restoring natural knee kinematics that might improve patient-reported satisfaction and function.
Subject(s)
Arthroplasty, Replacement, Knee , Biomechanical Phenomena , Congenital Abnormalities , Femur , KneeABSTRACT
Many factors contribute to a successful total knee arthroplasty, and postoperative coronal lower limb alignment has always been a focus of joint surgeons. Previous researches have suggested that neutral alignment can bring higher prosthesis survival rate and better knee function. However, the theory has been challenged in recent years.In this article, the author introduces the axis, alignment and osteotomy of total knee arthroplasty briefly and reviews the studies on the neutral alignment and kinematic alignment of recent years in order to provide some advice for the clinical operation.
ABSTRACT
BACKGROUND: Achieving neutral limb alignment during total knee arthroplasty (TKA) has been considered an important determinant in the long-term prosthesis survival. The purpose of this study was to evaluate the association between the immediate postoperative mechanical alignment of the lower limb and the rate of revision TKA by comparing an acceptable mechanical axis group (within ± 3° from neutral alignment) and an outlier group (> 3° deviation from neutral alignment). METHODS: Between 2000 and 2006, clinical and radiographic data of 334 primary TKAs were retrospectively reviewed to determine the 10-year Kaplan-Meier survival rate. Patients were divided into acceptable and outlier groups according to the mechanical axis checked postoperatively within a month. Clinical outcomes were assessed using Hospital for Special Surgery, Knee Society Score, and Western Ontario and McMaster Universities Osteoarthritis Index score preoperatively and at the final follow-up. Postoperative complications and revision rates were also evaluated. RESULTS: The mean change in mechanical axis between the immediate postoperative examination and the last follow-up was greater in the outlier group (1.6 ± 2.7) than in the acceptable group (0.8 ± 2.4). The revision rates were significantly different between the two groups (p = 0.04). At the last follow-up, clinical scores were all improved in both groups compared to each preoperative condition. There were no significant differences in clinical scores between the two groups at the last follow-up. The 10-year Kaplan-Meier survival analysis showed a tendency towards better survival with restoration of neutral mechanical axis. However, the difference was not statistically significant (p = 0.25). CONCLUSIONS: Restoration of neutral limb alignment is a factor that can result in a lower revision rate and higher longevity in TKA. However, there were no significant differences in clinical outcomes between the two groups.