Biologic augmentation in knee preservation surgery: A systematic review of procedure-specific evidence

Biologic augmentation is increasingly used across knee-preservation procedures, but evidence remains fragmented by procedure and biologic type. This review synthesised the available clinical evidence for biologic augmentation in meniscal repair, meniscus allograft transplantation (MAT), high tibial osteotomy (HTO), cartilage restoration, and osteochondral allograft (OCA) transplantation, with procedure-specific clinical interpretation.

A systematic review on Ovid MEDLINE and OVID EMBASE was performed (PROSPERO CRD420261342726). Eligible studies were human clinical investigations evaluating a biologic adjunct used concurrently with knee-preservation surgery. Risk of bias was assessed using RoB 2 for randomised trials and MINORS for non-randomised studies. Because outcome measures were heterogeneous, formal pooled meta-analyses was not undertaken, and an exploratory study-level quantitative analysis was performed.

Twenty-three clinical studies were included: 5 meniscal repair studies, 1 MAT study, 10 HTO-based studies, and 7 cartilage restoration or OCA studies. Nineteen of 23 studies reported an overall favourable effect, although this proportion should be interpreted cautiously because uncontrolled study designs and selective publication of positive studies were common. Among 16 comparative studies, 12 (75.0%) showed favourable comparative outcomes. Cell-based comparative studies were more often favourable than non-cell-based strategies (8/9 [88.9%] vs 4/7 [57.1%]; odds ratio 6.0, 95% CI 0.46-77.75; Fisher exact p = 0.262). Formal risk-of-bias assessment identified 1 low-risk RCT and 4 with some concerns.

Biologic augmentation should not currently be regarded as a routine strategy across knee-preservation surgery as a whole. The most coherent but still preliminary is selective use of cell-based augmentation in high tibial osteotomy-based cartilage-regeneration settings. Meniscal repair demonstrates a selective but inconsistent benefit, while evidence for meniscal allograft transplantation, focal cartilage restoration, and osteochondral allograft augmentation remains insufficient to support routine adoption. Future research should prioritise procedure-specific randomised trials, standardised reporting of biologic preparation and delivery methods, and greater emphasis on patient reported outcome measures alongside structural endpoints.