Preoperative HbA1c and early stiffness after total knee arthroplasty

Polish version: HbA1c przed endoprotezoplastyką kolana a ryzyko wczesnej sztywności po operacji

A study published online in The Journal of Arthroplasty on 24 August 2026 examined whether preoperative glycaemic control is associated with early arthrofibrosis after primary total knee arthroplasty (TKA). Higher HbA1c was associated with greater odds of manipulation under anaesthesia (MUA) or arthroscopic lysis of adhesions (aLOA) within the first 3 months.

Why this study matters

The association between diabetes and stiffness after TKA has been uncertain. A 2019 meta-analysis of 7 studies and 246,053 cases found no strong evidence of increased stiffness risk in patients with diabetes. The new analysis goes beyond a diabetes yes/no diagnosis by examining HbA1c strata and an endpoint reflecting clinically significant stiffness requiring intervention.

Study design

This retrospective database study included primary TKA procedures from 2006–2026. Patients were stratified by preoperative HbA1c: <5.7%, 5.7–6.9%, 7.0–7.9% and ≥8.0%. Propensity score matching was used before comparing MUA/aLOA during three periods: within 3 months, 3–12 months and after 12 months. The public abstract does not report cohort sizes.

Main results

• HbA1c 5.7–6.9%: OR 1.21 for MUA/aLOA within 3 months (95% CI 1.07–1.37).
• HbA1c 7.0–7.9%: OR 1.65 (95% CI 1.37–1.97).
• HbA1c ≥8.0%: OR 1.91 (95% CI 1.35–2.71).

No significant later differences were found for the 5.7–6.9% and 7.0–7.9% groups. In the ≥8.0% group, no significant difference was found at 3–12 months; analysis beyond 12 months was limited by too few reported events.

Clinical interpretation for an orthopaedic surgeon

The stepwise association with HbA1c is biologically plausible and suggests that poorer metabolic control may mark susceptibility to early postoperative stiffness. The endpoint, however, was an intervention rather than a direct range-of-motion measurement. It captures clinically important cases but also depends on local thresholds and institutional practice for MUA or aLOA.

Limitations

Propensity score matching reduces measured differences but cannot remove unmeasured confounding. The abstract does not explain in sufficient detail how preoperative motion, rehabilitation, surgical technique, implant choice, analgesia, patient motivation or intervention thresholds were captured.

The apparent difference from the 2019 meta-analysis may partly reflect varying definitions of stiffness in older studies and their lack of an HbA1c dose-response analysis.

Implications for practice

HbA1c may be useful in preoperative risk discussions and in identifying patients who merit closer monitoring of motion recovery. The findings also support considering metabolic optimisation beyond infection and wound-healing risk.

The study does not prove that lowering HbA1c before surgery reduces arthrofibrosis. It establishes no HbA1c threshold for postponing TKA and does not show that diabetes independently causes stiffness. Prospective evidence, ideally assessing an actual change in glycaemic control, is needed.

References

Hall RP, Braithwaite CL, Van Schuyver PR et al. Diabetes is Associated with an Increased Risk of Arthrofibrosis Following Total Knee Arthroplasty. The Journal of Arthroplasty. Published online August 24, 2026. DOI: 10.1016/j.arth.2026.08.041. PubMed · Journal website.

This summary is based solely on the publicly available abstract and metadata.

Context: Jump C, Malik RA, Anand A, Charalambous CP. Diabetes mellitus does not increase the risk of knee stiffness after total knee arthroplasty: a meta-analysis of 7 studies including 246 053 cases. Knee Surg Relat Res. 2019;31:6. DOI.

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Content prepared by: Tomasz Poboży - orthopaedic surgeon.