Hip and knee replacement under age 25 improves function, with higher revision rates than in older adults

Design

Systematic review and meta-analysis of 44 studies (PROSPERO registered; Level III)

Population

3,317 patients younger than 25 with 5,632 joints replaced

Primary outcome

Complications, function, quality of life and all-cause revision after hip and knee arthroplasty

Effect

Revision 8.7% (hip) and 12.4% (knee); periprosthetic joint infection 1.6% (hip) and 2.9% (knee)

This meta-analysis pooled 44 studies (3,317 patients, 5,632 joints) of total hip or knee arthroplasty in patients younger than 25 years. Most were retrospective cohorts.

After hip replacement, pooled periprosthetic joint infection was 1.6%, aseptic loosening 5.4%, periprosthetic fracture 1.4% and all-cause revision 8.7%. After knee replacement, infection was 2.9%, aseptic loosening 9.9% and revision 12.4%. Function and quality of life improved substantially after hip replacement (SMD 4.9 and 1.8). More recent patient cohorts had lower revision and infection rates after hip replacement.

For the clinician, this suggests arthroplasty is a reasonable option for end-stage joint disease in young patients, once other options are exhausted, with counselling that revision is likely over a lifetime. The data are heterogeneous in indication and implant, and come from a Level III review.

• Counsel young patients that revision was needed in roughly one in nine hips and one in eight knees in pooled data.
• Expect higher infection and loosening rates than in older adults; plan surveillance.
• Use newer implant designs and current technique; recent cohorts did better.
• Document the underlying diagnosis, since indications varied widely between studies.
• Involve a young-adult hip or joint preservation service where available.

Why it matters

Surgeons rarely see enough of these cases to counsel from experience, and the revision burden over a lifetime is the key number to share.

Don't overread it

A systematic review of retrospective cohorts of mixed indications; it cannot guide implant selection.

The statistics, in plain English

Pooled percentages from retrospective series can be biased by who was reported and followed. An SMD of 4.9 is unusually large for a clinical effect, which suggests pooled before-and-after scores from heterogeneous scales, so it should be read as direction rather than size. Follow-up length differed between studies, so revision rates are not directly comparable to registry survival curves.

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