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

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.