There is no standardised measurement approach for medial proximal tibial angle after unicompartmental knee arthroplasty: A systematic review
Bibliographic record
Abstract
PURPOSE: Unicompartmental knee arthroplasty (UKA) is increasingly used for isolated knee osteoarthritis. The medial proximal tibial angle (MPTA) is important for describing tibial alignment. However, MPTA measurement after UKA is challenging because one tibial compartment is prosthetic. This systematic review evaluated the measurement of MPTA after UKA, summarised methodological variability, and assessed the quality and reliability of the reported methods. METHODS: PubMed, Embase, Web of Science, and Scopus were searched. Eligible original studies reported radiographic MPTA measurement techniques in patients who underwent UKA. Two reviewers independently screened, extracted data, and assessed study quality using the Newcastle-Ottawa Scale. Due to methodological heterogeneity, a qualitative narrative synthesis was conducted. RESULTS: Twenty-three studies met the inclusion criteria, encompassing 4,075 patients and one cadaveric study with 26 specimens. Measurement reporting was heterogeneous and often incomplete: 12 studies did not specify their MPTA technique. Among the described approaches, three standard methods emerged: (1) using the tibial component coronal angle (TCA) as a proxy for MPTA, (2) connecting the proximal medial point of the prosthesis to a lateral native tibial landmark (medial-to-lateral joint line), and (3) the Cartier-type angle. Reliability reporting was limited: only six studies reported both inter- and intra-observer reliability with specific statistical measures, three reported inter-observer reliability only, three stated dual assessors without metrics, and eleven reported no reliability data. CONCLUSIONS: There is no standardised and validated method for MPTA measurement after UKA. Heterogeneity in landmarks and reliability reporting undermines the comparability of results across studies. A standardised and validated measurement approach for MPTA after UKA is urgently needed. LEVEL OF EVIDENCE: Level III.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.030 | 0.130 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.013 | 0.011 |
| Bibliometrics | 0.013 | 0.013 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.005 | 0.006 |
| Open science | 0.003 | 0.003 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".