The clinical relevance of cartilage regeneration and related basic science research: regenerating the orthopaedic clinician-scientist

Advancing regenerative surgery in orthopaedic sports medicine: the critical role of the surgeon

The constant desire to improve outcomes in orthopaedic sports medicine requires us to continuously consider the challenges faced in the surgical repair or reconstruction of soft tissue and cartilaginous injury. In many cases, surgical efforts targeted at restoring normal anatomy and functional status are ultimately impaired by the biological aspect of the natural history of these injuries, which acts as an obstacle to a satisfactory repair process after surgery. The clinical management of sports injuries and the delivery of appropriate surgical intervention are continuously evolving, and it is likely that the principles of regenerative medicine will have an increasing effect in this specialized field of orthopaedic practice going forward. Ongoing advances in arthroscopy and related surgical techniques should facilitate this process. In contrast to the concept of engineered replacement of entire tissues, it is probable that the earliest effect of regenerative strategies seen in clinical practice will involve biological augmentation of current operative techniques via a synergistic process that might be best considered "regenerative surgery." This article provides an overview of the principles of regenerative surgery in cartilage repair and related areas of orthopaedic surgery sports medicine. The possibilities and challenges of a gradual yet potential paradigm shift in treatment through the increased use of biological augmentation are considered. The translational process and critical role to be played by the specialist surgeon are also addressed. We conclude that increased understanding of the potential and challenges of regenerative surgery should allow those specializing in orthopaedic surgery sports medicine to lead the way in advancing the frontiers of biological strategies to enhance modern clinical care in an evidence-based manner.

Tissue engineering and regenerative medicine strategies in meniscus lesions

PURPOSE

The aim of this systematic review was to address tissue engineering and regenerative medicine (TERM) strategies applied to the meniscus, specifically (1) clinical applications, indications, results, and pitfalls and (2) the main trends in research assessed by evaluation of preclinical (in vivo) studies.

METHODS

Three independent reviewers performed a search on PubMed, from 2006 to March 31, 2011, using the term "meniscus" with all of the following terms: "scaffolds," "constructs," "cells," "growth factors," "implant," "tissue engineering," and "regenerative medicine." Inclusion criteria were English language-written, original clinical research (Level of Evidence I to IV) and preclinical studies of TERM application in knee meniscal lesions. Reference lists and related articles on journal Web sites of selected articles were checked until prepublication for potential studies that could not be identified eventually by our original search. The modified Coleman Methodology score was used for study quality analysis of clinical trials.

RESULTS

The PubMed search identified 286 articles (a similar search from 2000 to 2005 identified 161 articles). Non-English-language articles (n = 9), Level V publications (n = 19), in vitro studies (n = 118), and 102 studies not related to the topic were excluded. One reference was identified outside of PubMed. Thirty-eight references that met the inclusion criteria were identified from the original search. On the basis of our prepublication search, 2 other references were included. A total of 9 clinical and 31 preclinical studies were selected for further analysis. Of the clinical trials, 1 was classified as Level I, 2 as Level II, and 6 as Level IV. Eight referred to acellular scaffold implantation for partial meniscal replacement, and one comprised fibrin clot application. The mean modified Coleman Methodology score was 48.0 (SD, 15.7). Of the preclinical studies, 11 original works reported on studies using large animal models whereas 20 research studies used small animals. In these studies the experimental design favored cell-seeded scaffolds or scaffolds enhanced with growth factors (GFs) in attempts to improve tissue healing, as opposed to the plain acellular scaffolds that were predominant in clinical trials. Injection of mesenchymal stem cells and gene therapy are also presented as alternative strategies.

CONCLUSIONS

Partial meniscal substitution using acellular scaffolds in selected patients with irreparable loss of tissue may be a safe and promising procedure. However, there is only 1 randomized controlled study supporting its application, and globally, many methodologic issues of published trials limit further conclusions. We registered a different trend in preclinical trials, with most considering augmentation of scaffolds by cells and/or GFs, as opposed to the predominantly acellular approach in clinical trials. Different TERM approaches to enhance meniscal repair or regeneration are in preclinical analysis, such as the use of mesenchymal stem cells, gene therapy, and GFs alone or in combination, and thus could be considered in the design of subsequent trials.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I to IV studies.