Is Immediate Postoperative Mechanical Axis Associated with the Revision Rate of Primary Total Knee Arthroplasty? A 10-Year Follow-up Study

Abstract

BackgroundAchieving 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).MethodsBetween 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.ResultsThe 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).ConclusionsRestoration 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.

Affecting Factors and Correction Ratio in Genu Valgum or Varum Treated with Percutaneous Epiphysiodesis Using Transphyseal Screws

“…Malalignment of the knee produces pathologic stress on the unicompartmental joint space of the knee, increasing the risk of accelerated degenerative changes [ 2 ]. The current recommendation addresses lower limb angular deformities using mechanical axis assessment as early as possible to prevent consequences such as altered gait patterns, early articular cartilage degeneration, and soft tissue changes [ 3 , 4 , 5 , 6 ].…”

Robotic arm-assisted bi-unicompartmental knee arthroplasty maintains natural knee joint anatomy compared with total knee arthroplasty: a prospective randomized controlled trial

“… 12 This has been supported by studies which have shown lower revision rates in patients in whom the coronal alignment of the component was within 3° of neutral. 14 , 15 However, this concept overlooks the variable natural alignment seen by Bellemans et al 6 in the pre-disease knee of adolescents and young adults. Implanting components perpendicular to the mechanical axis may be beneficial for implant survivorship, but risks altering the patient's bony anatomy and may require more aggressive capsular and ligament releases to obtain soft tissue balancing.…”

“… 10 Although some studies have suggested that postoperative coronal lower limb and knee alignment (HKAA, MDFA, and MPTA) outside 3° from neutral does not predict implant failure, 26 – 28 most existing literature advocates keeping within this ‘safe zone’. 12 – 15 , 29 The effectiveness of kinematically aligned TKA may therefore be limited for patients with constitutional varus or valgus beyond 3° from neutral.…”

“… 9 - 11 However, concerns have been raised about implanting components beyond 3° perpendicular to the mechanical axis because of the risk of cantilever loading leading to early loosening, particularly on the tibial side, and of increased polyethylene wear leading to early failure. 12 - 15 Furthermore, restoring pre-disease joint alignment, while keeping within 3° parameters, can be difficult using a kinematic technique in the presence of severe varus or valgus deformities, particularly with manual implantation, when the accuracy of bone cuts cannot be assured. 8 …”

Acquisition of coronal alignment according to the degree of varus deformity in total knee arthroplasty using computer-assisted navigation

“…TKA is currently being performed to a relatively younger population, 9 and obtaining the coronal alignment of 0 + 3 is important for implant survival. 10,11 On such basis, the technique of computer-assisted navigation has been integrated to TKA and have been reported to be effective in obtaining the coronal alignment of 0 + 3 . [12][13][14] However, the fact that obtaining coronal alignment of 0 + 3 in all types of cases, regardless of cases with severe varus deformity, is questionable.…”