Why this study is important: avoiding overcorrection and joint line obliquity (JLO) in HTO
In varus knee osteoarthritis treated by isolated medial opening wedge high tibial osteotomy (OWHTO), one risk is tibial overcorrection, which can lead to an increase in the joint line obliquity (JLO) — an unfavourable outcome associated with altered knee biomechanics and potentially worse long-term joint health. Keywords: high tibial osteotomy planning, tibial overcorrection, joint line obliquity (JLO), mechanical axis correction varus knee, ESSKA consensus osteotomy indications.
Study overview: cohort analysis against new consensus guidelines
This retrospective study included 129 patients undergoing isolated OWHTO for symptomatic medial compartment osteoarthritis (Ahlbäck grade I or II) with global varus (HKA ≤ 177°) at a single centre.
The study used automated software to assess pre-operative full-length radiographs, applying recommendations from the recent European Society of Sports Traumatology, Knee Surgery & Arthroscopy (ESSKA) consensus: an isolated HTO is discouraged if the planned post-operative JLO would exceed 5° or the MPTA would exceed 94°.
Outcomes included the number of cases where post-operative MPTA > 94° (indicating tibial overcorrection) and cases where JLO > 5°. Multiple linear regression was used to identify factors predictive of unacceptable alignment.
Key findings: high rate of tibial overcorrection and increased JLO
- The software flagged that 17.8% (23/129) of cases should have undergone a double-level osteotomy (DLO) rather than isolated HTO.
- Post-operatively, 41.1% (53/129) had MPTA > 94° (i.e., tibial overcorrection), and 29.4% (38/129) had JLO > 5°.
- Higher pre-operative MPTA was significantly associated with the risk of post-operative MPTA > 94° (R² = 0.36; p < 0.001). A planned JLO > 5° also increased the probability of post-operative abnormal JLO (R² = 0.27; p < 0.001).
- The study emphasises that without adhering to consensus thresholds, isolated HTO may lead to too much tibial correction and undesirable joint line geometry.
Clinical implications & surgeon take-aways: planning beyond just the mechanical axis
- Keywords: alignment correction in varus knee, pre-operative planning thresholds HTO, joint line orientation in osteotomy, ESSKA osteotomy guideline adherence.
- Surgeons must evaluate not only global mechanical axis correction (HKA) but also the joint line obliquity (JLO) and medial proximal tibial angle (MPTA) when planning an isolated HTO.
- If pre-operative MPTA is high or predicted post-operative JLO exceeds 5°, then a double-level osteotomy (DLO) should be considered rather than isolated HTO.
- Failure to respect these thresholds may result in tibial overcorrection, increased JLO, and potentially compromised outcomes despite apparently correct mechanical axis.
Take-home messages
- A large proportion of patients undergoing isolated OWHTO without guideline-based planning experienced tibial overcorrection and increased JLO.
- Pre-operative planning must incorporate MPTA and JLO thresholds (e.g., MPTA > 94°, JLO > 5°) to decide whether isolated HTO is appropriate.
- Aligning to consensus guidance — not just aiming for mechanical axis targets — may improve the anatomical quality of correction and long-term knee health.
Link to full paper: A significant rate of tibial overcorrection with an increased JLO occurred after isolated high tibial osteotomy without considering international consensus
Sources used in report overview:
- https://www.researchgate.net/publication/373236519_A_significant_rate_of_tibial_overcorrection_with_an_increased_JLO_occurred_after_isolated_high_tibial_osteotomy_without_considering_international_consensus?_tp=eyJjb250ZXh0Ijp7InBhZ2UiOiJzY2llbnRpZmljQ29udHJpYnV0aW9ucyIsInByZXZpb3VzUGFnZSI6bnVsbH19
- https://pubmed.ncbi.nlm.nih.gov/37597039/
- https://www.sciencedirect.com/science/article/pii/S0942725823002895
