Similar results with kinematic and mechanical alignment applied in total knee arthroplasty

Abstract

Purpose This meta‐analysis compared the results of kinematic alignment (KA) and mechanical alignment (MA) applied in total knee arthroplasty (TKA). Methods Randomized controlled trials and cohort studies comparing functional, radiological, and perioperative results and complications in TKA with KA and MA were collected from databases and included in the analysis. Results Nine trials were included. KA showed a better performance in terms of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) (mean difference [MD] = − 9.06, 95% confidence interval [CI] − 14.69, − 3.42) and Oxford knee score (OKS) (MD = 4.72, 95% CI 0.24, 9.21); however, the Knee Society score (KSS), knee injury and osteoarthritis outcome score (KOOS), EuroQoL 5‐dimension questionnaire (ED‐5D), range of motion, and complications were similar for KA and MA (n.s.). KA resulted in slightly more varus alignment in the tibia [mechanical medial proximal tibial angle (mMPTA) MD = − 2.45, 95% CI − 2.89, − 2.01) and more valgus alignment in the femur (mLDFA MD = − 2.06, 95% CI − 2.48, − 1.65) than MA (P < 0.05), but showed similar results in terms of the joint line orientation angle (JLOA) (MD = 0.54, 95% CI − 2.59, 3.66), hip–knee–ankle angle (HKA), anatomical knee angle (AKA), femoral flexion–extension angle (FFA), and tibial slope (TS). The preoperative results, including the incision length, hospital stay, and changes in hemoglobin, were also similar. Conclusion KA achieved functional, radiological, and perioperative results similar to those of MA and did not increase the complication rate. KA is an acceptable and satisfactory method for application in TKA. Level of evidence III.

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

“…Some studies indicated that the KA technique achieved a greater range of motion (ROM) and a higher rate of postoperative satisfaction compared with MA in TKA [6,7]. However, several researches suggested similar results with these two alignment techniques [8]. Hence, we speculate that the KA or MA alignment technique may not be suitable for every case, which means surgeons should choose KA or MA individually.…”

“…The primary outcome was Knee Society Score (KSS) 2011 [10], including symptoms (0-25), satisfaction (0-40), expectation (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15), and functional activities (0-100) at the 1-year followup. Secondary outcomes included the range of motion (ROM) and the HKA angle.…”

Kinematic alignment in total knee arthroplasty

“…However, in the analysis of functional outcome scores the same study was used twice from Dossett et al 19 , 57 For KSS and Knee Society Function Scores (KSFS) they extrapolated data from an incomplete study. 58 Luo et al 59 concluded KA achieved functional, radiological and peri-operative results similar to those of MA without an increase in the complication rates. This paper did have some significant flaws in that the forest plots were incorrect due to an error in how the outcomes scores (WOMAC, OKS and KSS) were interpreted, and the meta-analysis included studies with different techniques for TKR alignment including KA, rKA and AA.…”

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

“…Some studies indicated that the KA technique achieved greater range of motion (ROM) and higher rate of postoperative satisfaction compared with MA in TKA [6,7]. However, several researches suggested similar results with these two alignment techniques [8]. Hence, we speculate that the KA or MA alignment technique may be not suitable for every case, which means surgeons should choose KA or MA individually.…”

“…The main outcome was Knee Society Score (KSS) 2011 [10], including symptom (0-25), satisfaction (0-40), expectation (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) and functional activities (0-100) at the 1-year followup. Secondary outcomes included the range of motion (ROM) and HKA angle.…”