Stem cells in the knee

Editorial Commentary: Platelet-Rich Plasma: Fountain of Youth, Cart Before the Horse, or Both?

Platelet-rich plasma (PRP) injections have gained widespread popularity for the treatment of many orthopaedic conditions including osteoarthritis of the knee. Despite its increasing usage, there is comparatively little evidence regarding the mechanisms of action and relative roles of the multiple growth factors contained within PRP. That said, although future research will clarify the issue, current evidence suggests that PRP is safe and, for the treatment of knee osteoarthritis, effective.

Emerging Concepts in Treating Cartilage, Osteochondral Defects, and Osteoarthritis of the Knee and Ankle

The management and treatment of cartilage lesions, osteochondral defects, and osteoarthritis remain a challenge in orthopedics. Moreover, these entities have different behaviors in different joints, such as the knee and the ankle, which have inherent differences in function, biology, and biomechanics. There has been a huge development on the conservative treatment (new technologies including orthobiologics) as well as on the surgical approach. Some surgical development upraises from technical improvements including advanced arthroscopic techniques but also from increased knowledge arriving from basic science research and tissue engineering and regenerative medicine approaches. This work addresses the state of the art concerning basic science comparing the knee and ankle as well as current options for treatment. Furthermore, the most promising research developments promising new options for the future are discussed.

Editorial Commentary: Thinking "Inside the Box" Yields the Possibility of Harvesting Stem Cells From "Inside the Injured Knee"

Looking to the injured knee for potential stem cell harvesting has attractive benefits. Stem cells can be successfully harvested but the concentrations with the current technology are lower than bone marrow or lipoaspirate sites. The technique of utilizing the knee effusion and tissue by-products after cruciate ligament injury shows future promise.

Editorial Commentary: Doc, Can You Inject Stem Cells in My Knee?

Stem cell therapy is one of the most promising treatments to restore and repair damaged articulate cartilage. Koh et al. present in this issue their study on the treatment of articulate cartilage defects with adipose derived stem cell. We believe that it is a matter of time to when stem cells will become cost effective and commercially available for the treatment of articulate cartilage injuries.

High Tibial Osteotomy in Combination With Chondrogenesis After Stem Cell Therapy: A Histologic Report of 8 Cases

PURPOSE

To histologically evaluate the quality of articular cartilage regeneration from the medial compartment after arthroscopic subchondral drilling followed by postoperative intra-articular injections of autologous peripheral blood stem cells (PBSCs) and hyaluronic acid with concomitant medial open-wedge high tibial osteotomy (HTO) in patients with varus deformity of the knee joint.

METHODS

Eight patients with varus deformity of the knee joint underwent arthroscopic subchondral drilling of International Cartilage Repair Society (ICRS) grade 4 bone-on-bone lesions of the medial compartment with concomitant HTO. These patients were part of a larger pilot study in which 18 patients underwent the same procedure. PBSCs were harvested and cryopreserved preoperatively. At 1 week after surgery, 8 mL of PBSCs was mixed with 2 mL of hyaluronic acid and injected intra-articularly into the knee joint; this was repeated once a week for 5 consecutive weeks. Three additional intra-articular injections were administered weekly at intervals of 6, 12, and 18 months postoperatively. Informed consent was obtained at the time of hardware removal for opportunistic second-look arthroscopy and chondral biopsy. Biopsy specimens were stained with H&E, safranin O, and immunohistochemical staining for type I and II collagen. Specimens were graded using the 14 components of the ICRS Visual Assessment Scale II, and a total score was obtained.

RESULTS

Second-look arthroscopy showed satisfactory healing of the regenerated cartilage. Histologic analysis showed significant amounts of proteoglycan and type II collagen. The total ICRS Visual Assessment Scale II histologic scores comparing the regenerated articular cartilage (mean, 1,274) with normal articular cartilage (mean, 1,340) indicated that the repair cartilage score approached 95% of the normal articular cartilage score. There were no infections, delayed unions, or nonunions.

CONCLUSIONS

Chondrogenesis with stem cells in combination with medial open-wedge HTO for varus deformity correction of the knee joint regenerates cartilage that closely resembles the native articular cartilage.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Editorial Commentary: Stem Cell Research in Arthroscopy Is Scant and Requires Basic Science Review

Stem cell research in Arthroscopy is rare, but review of journals beyond orthopaedics yields many interesting highlights. The key points are that sources of stem cells vary with regard to cellular yield, but manipulation to improve the yield is severely limited by the United States Food and Drug Administration.

Editorial Commentary: Effects of PRP on Cartilage Repair Using Scaffolds Are Inconclusive

Effects of PRP on cartilage repair using scaffolds are, in the clinical setting, inconclusive. Biologics research is confounded by the variety and heterogeneity of stem cells, scaffolds, PRP preparations, other growth factors, and other biological stimulants.

Editorial commentary: tissue engineering in knee arthroscopic and related surgery

Stem cells are guided by scaffolds, induced by growth factors, and stimulated by biomechanical forces, with a goal of engineering clinically competent cartilage, meniscus, tendon, or ligament tissue. Translational research, to move us from the preclinical to the clinical phase, is today necessary.

Editorial commentary: meniscal tissue engineering

Meniscal tissue engineering requires cells, scaffolds, growth factors, biomechanical stimulation, and biochemical stimulation. Preclinical work is assiduous; however, we are today, unaware of any clinical reports of meniscal tissue engineering in the literature.

Editorial commentary: collagen meniscal scaffolds

Small collagen meniscal scaffolds are a treatment for partial meniscectomy, which is clinically much more common than subtotal or total meniscectomy. The scaffold alone shows promising results, but readers must be mindful of risk of bias in the literature. Addition of stem cells and growth factors is the next step in meniscal tissue engineering.

Editorial commentary: autologous chondrocyte implantation versus microfracture

Autologous chondrocyte implantation (ACI) shows greater durability, lower failure rates, and is effective for larger lesions, compared with microfracture. In addition, membrane-ACI (M-ACI) is technically simpler with fewer complications of cartilage hypertrophy than first-generation ACI using periosteum. However, second-generation, M-ACI is not yet approved for general use in the United States.

Editorial commentary revisited and the spin move refined

First, editorial commentary: editorial commentary may be educational and may be controversial, but above all else, authors come first. Second, The Spin Move: The Spin Move is effective, cost-effective, and ubiquitous because, while many techniques are specific to a single joint, The Spin Move can be performed as a part of any arthroscopic and related procedure. However, like many advanced procedures, The Spin Move, when poorly executed, entails substantial risk. Preoperative planning is essential, and The Spin Move must be reviewed by inexperienced practitioners, in detailed text, figures tables, and video, at www.arthroscopytechniques.org. Practice makes perfect.