{
  "abstract": "Objective This study aims to compare early pain relief and functional recovery between varus and non-varus phenotypes following robot-assisted mechanically aligned total knee arthroplasty (MA-TKA), with a specific focus on the two most common varus subtypes: Type I and Type IV. Methods A retrospective analysis was performed on 124 patients who underwent primary unilateral robot-assisted MA-TKA. Patients were classified according to the Coronal Plane Alignment of the Knee (CPAK) classification based on preoperative arithmetic hip-knee-ankle angle (aHKA) and joint line obliquity (JLO). Based on aHKA, patients were categorized into a varus group (CPAK Types I, IV, and VII, n = 93) and a non-varus group (neutral and valgus phenotypes, n = 31). Within the varus cohort, the two most prevalent subtypes — Type I (n = 64) and Type IV (n = 27) — were compared; Type VII (n = 2) was excluded from subtype-specific analyses due to small sample size. Patient-reported outcomes (VAS pain, KSS clinical/function, WOMAC) were evaluated preoperatively and at 1, 3, and 6 months postoperatively. Radiographic parameters (aHKA, MPTA, LDFA, JLO) were measured preoperatively and at 1 month. Results Preoperatively, the varus group had a significantly lower aHKA than the non-varus group (− 6.9° ± 2.4° vs. −0.1° ± 1.1°, p < 0.001). Postoperatively, both groups achieved neutral mechanical alignment with no significant difference in aHKA (p = 0.231). However, residual joint line obliquity differed significantly between Type I and Type IV knees (176.2° ± 0.2° vs. 179.3° ± 0.3°, p < 0.001). Non-varus patients had significantly better functional recovery at 1 month than varus patients (KSS‑Function: 60.5 ± 2.8 vs. 53.8 ± 3.1, p = 0.042; WOMAC: 36.2 ± 1.9 vs. 43.0 ± 2.3, p < 0.001), and these differences attenuated by 6 months. Within the varus subgroup, Type IV patients had lower 1‑month VAS scores and higher KSS‑Function scores than Type I patients (VAS: 3.5 ± 0.4 vs. 4.2 ± 0.4, p = 0.018; KSS‑Function: 55.0 ± 2.5 vs. 53.3 ± 2.9, p = 0.039). Conclusions Preoperative CPAK phenotype is associated with early recovery after robot-assisted MA‑TKA. Non-varus patients had higher 1‑month KSS‑Function scores than varus patients. Among varus knees, Type IV patients had lower 1‑month VAS scores and higher 1‑month KSS‑Function scores than Type I patients, whereas Type I knees retained greater residual postoperative joint line obliquity. Distinguishing varus subtypes may help refine prognostic expectations and guide individualized alignment strategies.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Orthopaedics, Zhejiang Rongjun Hospital",
    "Department of Gastroenterology, Zhejiang Rongjun Hospital"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Pengpeng Li"
    },
    {
      "affs": [
        0
      ],
      "name": "Jihe Ban"
    },
    {
      "affs": [
        0
      ],
      "name": "Yunhai Liu"
    },
    {
      "affs": [
        1
      ],
      "name": "Juan Li"
    },
    {
      "affs": [
        0
      ],
      "name": "Jichao Hu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2agax6wsek6xz.bib",
  "cited_by": 0,
  "doi": "10.1186/s12891-026-10253-w",
  "fulltext_url": "https://doi.org/10.1186/s12891-026-10253-w",
  "id": "2agax6wsek6xz",
  "issns": [
    "1471-2474"
  ],
  "landing_url": "https://doi.org/10.1186/s12891-026-10253-w",
  "language": "en",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "lcc",
      "RC925-935"
    ],
    [
      "openalex",
      "2746|Total Knee Arthroplasty Outcomes"
    ]
  ],
  "openalex": "W7169882446",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-07-01",
  "publisher": "BMC",
  "ris": "https://research.draconitic.com/paper/2agax6wsek6xz.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T13:45:35Z",
      "native_id": "8ddb66851aa34219a60016f39b280f2f",
      "source": "doaj",
      "url": "https://doi.org/10.1186/s12891-026-10253-w"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2746|Total Knee Arthroplasty Outcomes",
      "subfield": "surgery"
    }
  ],
  "title": "Robot-assisted mechanically aligned total knee arthroplasty: comparing early outcomes between varus and non-varus knees, and between CPAK Type I and Type IV subtypes",
  "title_text": "Robot-assisted mechanically aligned total knee arthroplasty: comparing early outcomes between varus and non-varus knees, and between CPAK Type I and Type IV subtypes",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T13:45:35Z",
  "url": "https://research.draconitic.com/paper/2agax6wsek6xz",
  "venue": "BMC Musculoskeletal Disorders",
  "versions": []
}