Summary

Sub-chondroplasty reduces pain, improves function improvement, and has lower risk of conversion to total knee arthroplasty.

Abstract

Introduction

There is an ongoing interest in alternatives to total knee arthroplasty (TKA) as means to delay the inevitable knee replacement. A possible minimally invasive alternative is sub-chondroplasty which involves interosseous injection of bone substitute materials such as calcium phosphate (CaPo4), platelet-rich plasma (PRP) or bone marrow aspirate concentrate (BMAC) into the subchondral bone.

Methods

This metanalysis was conducted according to PRISMA protocol and the Cochrane Handbook for Systematic Reviews of Interventions. Online databases (PubMed, EMBASE and web of Science) and manually retrieving of cross references were searched. The selection process yielded 11 clinical trials investigating the effectiveness of CaPo4, PRP, and BMAC sub-chondroplasty. A non-stratified and stratified meta-analysis of the included studies were conducted to test for confounding and biases across the different types of included trials. Our non-stratified and stratified analyses used both random and fixed-effect models to estimate the effect size and incidence probability. The methodological quality and risk of bias of the included studies were analyzed and appraised using the Methodological index for non-randomized studies (MINORS) and Modified Coleman Methodology Score (MCMS).

Results

From 2015 to 2020, 391 patients were enrolled in the 11 clinical trials. Fifty-five percent of those participants were females. The average age across the trials was 55.72 years-old ranging from 41.7 to 67.7 years. The mean Body Mass Index (BMI) across the trials was 30.01. Most of the trials recruited patients with knee osteoarthritis with a severity grade of 1-4 on the Kellgren-Lawence (K-L) grade. K-L grades I-II are considered as early OA; grades III-IV as advanced OA. The average follow-up duration across the trials was 16.3 (6-36 months). The type of injectables used across the 11 clinical trials were variable. Six of these trials have injected Calcium Phosphate (CaPo4) in the sub-chondral bone of Knee. Platelet Rich plasma (PRP) was investigated in 4 trials. Only one trial has studied the effect of Bone Marrow Aspirate Concentrate (BMAC) in treating BMLs. Non-stratified analysis-regardless, the type of injectables- demonstrated that patients would have a significant improvement in the average Visual Analog Scale (VAS) scores after subchondroplasty, as compared to baseline. (MD = 4.40, P < 0.00001). However, the stratified analysis revealed that only CaPo4 injectables could provide significant pain relief (MD = 5.04, 95% CI: 4.30 to 5.79, P < 0.00001). Both non-stratified and stratified demonstrated that there is a statistically significant improvement of 22.61 points in the postoperative Knee Injury and Osteoarthritis Outcome Score (KOOS) scores as compared to the baseline scores. (non-stratified, MD = -22.61, P < 0.00001), (CaPo4, MD = -33.12, P < 0.00001), (PRP, MD = -15.51, P=0.006). The CaPo4 and PRP subchondroplasty were associated with 8% and 2% risk of conversion to arthroplasty, respectively. Most included studies had some methodological limitations, with an average MINORS score of 12.27 +/- 3.26 and a wide range of 6-16 and an average Coleman methodology score of 51.27 +/- 12.75 (range 30-67).

Discussion

Sub-chondral intraosseous injections may be safe and cost-effective minimally invasive procedure to delay the inevitable knee replacement.