Knee Joint Distraction and Implantable Shock Absorbers for Knee Osteoarthritis: A Systematic Review of Joint-Preserving Outcomes, Structural Changes, and Complications.

In 30 seconds

This PRISMA-based systematic review synthesized clinical, structural, biomarker, and safety outcomes of knee joint distraction (KJD) and implantable medial compartment shock absorbers (ISA) for tibiofemoral knee osteoarthritis. Seventeen studies—13 of KJD and 4 of ISA—reported on approximately 400 patients. In a narrative synthesis, KJD was associated with clinically important symptom improvement at 1 to 2 years and arthroplasty-free survival of roughly 75% to 85% at 5 to 9 years in selected series. ISA improved pain and function, with higher 2-year arthroplasty-free survival than HTO or non-operative comparators. Evidence certainty was low to moderate.

Key findings

• KJD studies reported clinically important WOMAC/KOOS and VAS pain improvements at 1 to 2 years.
• Selected KJD series reported arthroplasty-free survival of roughly 75% to 85% at 5 to 9 years.
• KJD was accompanied by increased radiographic joint-space width and MRI-derived cartilage thickness in the most affected compartment.
• ISA improved WOMAC pain and function and had higher 2-year arthroplasty-free survival than HTO or non-operative comparators.

Why it matters

These joint-preserving approaches may offer symptom relief and defer arthroplasty for carefully selected patients with tibiofemoral osteoarthritis. The review also describes structural changes with KJD and comparative survival findings for ISA, while emphasizing that the procedures have different indications and mechanisms. The evidence remains limited, so these findings inform consideration of options rather than establishing broad comparative effectiveness.

What to keep in mind

The evidence came from small, heterogeneous cohorts with overlapping populations and low-to-moderate certainty; clinical and methodological heterogeneity precluded quantitative meta-analysis.