Evidence map›Paper›PMID 42704404›Full record

ArticleJournal of robotic surgery2026

Medial expected gap (mEG): a quantitative, biology-guided predictor of coronal plane correction and knee balance in robotic functionally aligned total knee arthroplasty.

Harish Kumar Murugesan, Rex Chandrabose, T P Avinash, C Premanand

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Article in Journal of robotic surgery, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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5 · Who and what money

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4 authors.

Harish Kumar MurugesanDivision of Robotics & Arthroplasty, Rex Ortho Hospital, 43 RR Layout, RS Puram, Tamil Nadu, 641002, Coimbatore, India. arthro.harish@gmail.com.ORCID http://orcid.org/0000-0001-8207-1213
Rex ChandraboseDepartment of Orthopedics, Rex Ortho Hospital, 43 RR Layout, RS Puram, 641002, Coimbatore, Tamil Nadu, India.ORCID http://orcid.org/0000-0002-7267-8000
T P AvinashDepartment of Orthopedics, Rex Ortho Hospital, 43 RR Layout, RS Puram, 641002, Coimbatore, Tamil Nadu, India.ORCID http://orcid.org/0000-0002-3793-032X
C PremanandDivision of Sports Medicine & Arthroscopy, Rex Ortho Hospital, 43 RR Layout, RS Puram, Tamil Nadu, 641002, Coimbatore, India.ORCID http://orcid.org/0000-0002-2356-7865

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Osteophyte excision during total knee arthroplasty (TKA) influences gap balancing and deformity correction, but its effect on medial gap behavior remains poorly defined. This study evaluated the relationship between osteophyte burden, medial expected gap (mEG), and coronal correction in robotic assisted functional alignment TKA. This prospective study included 82 knees. Preoperative computed tomography images were used to measure medial tibial and femoral osteophytes. Following pilot development, mEG was calculated using an average osteophyte burden model with a non-linear physiological constraint capped at < 4 mm. Virtual gap balancing intentionally preserved the calculated mEG as medial tightness within predefined functional-alignment boundaries. Associations between osteophyte burden, mEG, coronal plane correction, and final knee balance were analyzed using correlation, regression, and group comparison statistics with bootstrap resampling for internal model validation. Raw medial osteophyte size demonstrated no significant association with lateral laxity severity (p = 0.357) or varus correctability (p = 0.302). Medial tibial (β = 0.12; p < 0.001) and medial femoral osteophytes (β = 0.16; p < 0.001) independently predicted mEG (R² = 0.47). Total osteophyte burden increased significantly across ascending mEG categories (p < 0.001), while final mEG values remained within a narrow physiological range. Mean coronal plane correction increased from 4.3° (mEG 1 mm) to 9.7° (mEG 4 mm) (p < 0.001). All knees achieved acceptable balance: 42 best balanced, 32 good, and 8 acceptable. Bootstrap internal validation supported the stability of the principal regression findings. The mEG provides a quantitative framework linking osteophyte burden to medial gap behavior, enabling preoperative planning of medial tightness and reproducible coronal correction during robotic assisted functional alignment TKA.Level of evidence: Level II, prospective cohort study.

Indexed as

Arthroplasty, Replacement, KneeKnee JointOsteophyteRobotic Surgical ProceduresAgedFemaleHumansMaleMiddle AgedProspective StudiesTomography, X-Ray ComputedFunctional alignmentGap balancingMedial expected gap (mEG)Osteophyte burdenRobotic-assisted total knee arthroplastySoft-tissue balancingVarus knee deformity

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.