ArticleArchives of orthopaedic and trauma surgery2025
Reproducibility of coronal plane alignment of the knee (CPAK) using tibia-first restricted inverse kinematic alignment.
Article in Archives of orthopaedic and trauma surgery, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 4 papers.
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Who cites it
4 citing papers in PubMed.
- Pre-resection ligament balance more frequently reproduces joint line orientation compared to inverse-kinematic workflow in robotic total knee arthroplasty.Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA · 2026Article
- Use of the VELYS Robotic-Assisted Solution in knee arthroplasty: A scoping review.Journal of experimental orthopaedics · 2026Review
- Robotic-assisted restricted kinematic alignment in total knee arthroplasty: A multicenter retrospective assessment of coronal phenotypes and early postoperative outcomes.Journal of experimental orthopaedics · 2026Article
- Beyond the CPAK dogma: robotic FA preserves CPAK better than MA but with equivalent proms at 5-year follow-up.Archives of orthopaedic and trauma surgery · 2025Article
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7 authors.
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Abstract
introductionThe Coronal Plane Alignment of the Knee (CPAK) classification categorizes knee phenotypes based on constitutional limb alignment and joint line obliquity (JLO). Restricted Inverse Kinematic Alignment (RIKA) is a surgical philosophy that incorporates calculated perioperative parameters to achieve patient-specific alignment. This study investigated the reproducibility of restoring preoperative CPAK phenotypes via the tibia-first RIKA concept in total knee arthroplasty (TKA).
methodsThis prospective study assessed 129 patients who underwent RIKA TKA using an imageless navigation robotic-assisted arm with a single implant design for primary osteoarthritis between January 2022 and December 2023. Preoperative and postoperative angles for the lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) were measured from full-length standing anteroposterior X-ray imaging. Arithmetic HKA (aHKA) was defined as MPTA - LDFA, and JLO was outlined as MPTA + LDFA to classify each knee into one of nine CPAK phenotypes. CPAK boundaries for neutral aHKA and JLO were 0° ± 2° and 180° ± 3°, respectively.
resultsThe mean pre- and postoperative aHKA were - 2.73° (SD ± 4.9°) vs. -2.83° (SD ± 3.0°), respectively. The most common preoperative CPAK phenotypes were I (n = 74, 42.5%) and II (n = 40, 23.0%). Among patients with preoperative type I phenotype, 39.2% (29/74) preserved their composition postoperatively, while 48.6% (36/74) converted to type IV. Of 40 Type II knees, 65.0% (26/40) preserved alignment, with 25.0% (10/40) shifting to type V. In preoperative types IV and V, 75% (12/16) and 88.5% (23/26) preserved their phenotypes, respectively. Valgus categories (III, VI, IX) were neutralized into types II and V. CPAK types VII, VIII, and IV were rare throughout.
conclusionThe use of tibia-first RIKA achieved adequate preservation of the native coronal alignment postoperatively. These findings suggest that balancing a knee using tibia-first approach with the use of imageless navigation robotic-assisted systems is a valid tool for surgeons who seek contemplating RIKA TKA.
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