Hypothermically Stored Amniotic Membrane for the Treatment of Cartilage Lesions: A Single-Arm Prospective Study with 2-Year Follow-Up

Abstract

Objective: The purpose of this study was to determine the safety and efficacy of hypothermically stored amniotic membrane (HSAM) for the treatment of cartilage lesions of the knee using imaging, patient-reported outcomes (PROs), second-look arthroscopy, and histology. Patients were treated with HSAM and followed for 2 years.

Design: Subjects with focal chondral lesions of the femur (International Cartilage Repair Society grade 3-4) were enrolled in this single-arm prospective study. Standard of care imaging was completed. PROs, including the Knee Injury and Osteoarthritis Outcome Score (KOOS), Marx Activity Scale, and Visual Analog Scale (VAS), were collected at baseline and at 3, 6, 12, 18, and 24 months. Three subjects underwent an optional arthroscopy and biopsy of the repair at 24 months.

Results: Ten subjects were enrolled and completed the study. At 24 months, KOOS Sports & Recreation improved 173.3% and Quality of Life improved 195.3% from baseline. Marx Activity Scale increased 266.8% from 12 to 24 months. VAS scores improved 84.8% and 81.0% from baseline to 24 months for average and maximum pain. Modified Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scoring showed that 7 of 10 subjects had complete defect repair and filling by 24 months. Biopsy staining for collagen II revealed integration and remodeling of HSAM into a mix of hyaline-like cartilage and fibrocartilage matrix.

Conclusion: This study provides evidence supporting the safety and efficacy of HSAM for treating symptomatic cartilage lesions. Subjects showed a high degree of defect fill and integration with the native cartilage and reported improvements in pain and function post-treatment. Results provide important original data for future clinical trials.

Trial registration: ClinicalTrials.gov NCT02837484.

Keywords: amniotic membrane; cartilage repair; chondral defect.

Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: K.A.K., G.J.H., and K.C.M. are employees of Organogenesis.

Figures

Figure 1.

Consolidated Standards of Reporting Trials flow diagram used to describe the grouping and flow of patients through the clinical trial. HSAM = hypothermically stored amniotic membrane.

Figure 2.

KOOS subscores for the entire 24-month period. Average ± standard error reported for (A) KOOS Symptoms, (B) KOOS Pain, (C) KOOS Activities of Daily Living, (D) KOOS Sports & Recreation, and (E) KOOS Quality of Life. KOOS = Knee Injury and Osteoarthritis Outcome Score.

Figure 3.

VAS subscores for the entire 24-month period. Average ± standard error reported for (A) VAS Average Pain and (B) VAS Maximum Pain. VAS = Visual Analog Scale.

Figure 4.

MRI images from preoperative and 24 months post-implantation with hypothermically stored amniotic membrane for each patient. White arrows indicate the presence of medial femoral condyle chondral defect or trochlear defect. MRI = magnetic resonance imaging. Patient 4 had an osteotomy plate on tibia, which distorted the 24-month MRI image (denoted by an asterisk).

Figure 5.

Representative immunohistochemistry images from biopsies from 3 patients. Negative controls for aggrecan, lubricin, collagen I, and collagen II, shown on the left, and staining for aggrecan, lubricin, collagen I, and collagen II, shown on the right for each patient. All images taken using a 2x objective.

Figure 6.

Representative histologic images from biopsies from 3 subjects with hematoxylin & eosin staining. (A,E,I) 2x magnification, (B,C,F,G,J,K) 10x magnification, and (D,H,L) 20x magnification. Black arrows indicate integration/border zone of hypothermically stored amniotic membrane and native cartilage within each biopsy.

Figure 7.

Representative histologic images from biopsies from 3 subjects with collagen II staining. (A,E,I) Negative control at 2x magnification, (B,F,J) collagen II staining at 2x magnification, and (C,D,G,H,K,L) collagen II staining at 10x magnification. Black arrows indicate integration/border zone of hypothermically stored amniotic membrane and native cartilage within each biopsy.

Figure 8.

Three subject series including arthroscopic images preoperatively and at 24 months postoperatively, and histological images of the 24-month biopsy, including Alcian blue, Masson’s trichrome, and hematoxylin & eosin staining. All histological images taken using a 2x objective.