Talk to a Concierge  →
Home  ›  Related Resources  ›  Beijing Jishuitan Hospital  ›  Partial knee replacement study
Clinical Research · English Editorial Summary

Mild "bone bruises" on both sides of the knee did not worsen partial knee replacement results

A Jishuitan Hospital study in The Bone & Joint Journal followed 124 partial knee replacement patients for a mean of 6.4 years: mild bone marrow lesions on the outer side of the knee did not reduce pain relief, function or alignment.

Original report: 18 September 2026English summary: 28 September 2026Source: Jishuitan Hospital official websiteEdited by Wellward China
Beijing Jishuitan HospitalBeijingBones, Joints, Spine & MusclesKnee osteoarthritisUnicompartmental knee arthroplasty (UKA)Bone marrow lesionsKnee-preserving surgery
Source and editorial note: This is an original English summary based on Beijing Jishuitan Hospital's Chinese-language report, published 18 September 2026. It is not a full translation or an independent clinical assessment. The hospital's source is the authority for the original announcement.
The study

Who can still keep their knee?

Unicompartmental knee arthroplasty (UKA) — replacing only the worn inner side of the knee joint — is a "knee-preserving" option for single-compartment osteoarthritis. It is popular with patients because it is smaller, recovery is faster, and more of the knee's own feel is retained. But pre-operative MRI often shows not only bone marrow lesions (BMLs, formerly called bone marrow oedema) on the inner side, but also mild changes on the outer side. Surgeons have worried that the realignment after inner-side UKA might worsen the outer compartment and lead to poorer results or faster arthritis there.

A team led by Huang Ye and Cao Guanglei in Jishuitan Hospital's knee-preserving surgery department addressed this question in a study published in The Bone & Joint Journal (BJJ), an international leading orthopaedic journal.

What the study found

The retrospective cohort covered patients who received medial UKA between January 2016 and December 2019 and had complete pre-operative MRI. They were divided into a group with medial BMLs only (86 patients) and a group with both medial and lateral BMLs (38 patients). Follow-up averaged 6.4 years.

Key results at a mean of 6.4 years

Pain (NRS) and function (Oxford Knee Score) improved significantly in both groups, with no significant difference between them. Correction of leg alignment was equally good. Imaging progression of outer-compartment arthritis was similar (12.8% vs 13.1%), no pathological radiolucencies appeared, and no patient needed revision surgery because of outer-compartment progression. Adjusted for age, sex and BMI, combined lateral BMLs were not an independent risk factor for worse Oxford Knee Score improvement.

What it means — and what it does not

The authors' conclusion is deliberately narrow: in patients without severe outer-side cartilage damage or lateral meniscal extrusion, mild lateral BMLs did not worsen mid-term results. That matters because it widens the group of patients who can reasonably choose partial rather than total knee replacement, avoiding the larger operation for patients who do not need it.

The limits are also clear: this is a single-centre retrospective cohort of 124 patients, not a randomised trial, and MRI interpretation of BMLs can vary. The study defines who was not harmed in this cohort; it does not prove every patient with lateral changes is a good UKA candidate.

Relevance to knee arthritis decisions

"Partial or total knee replacement?" is one of the most common questions international patients bring. Jishuitan Hospital is a national orthopaedic medical centre, and its knee-preserving surgery department runs training programmes for the technique. This summary belongs to the Bones, Joints, Spine & Muscles health area; it is evidence about patient selection, not advice for any individual's surgery choice.