Osteoarthritis Cartilage. 2015 Mar;23(3):469-77.

The use of hyperosmotic saline for chondroprotection: implications for orthopaedic surgery and cartilage repair.

N.M. Eltawil1, S.E.M. Howie2, A.H.R.W. Simpson3, A.K. Amin3, and A.C. Hall1.

 

1Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, United Kingdom.

2MRC Centre for Inflammation Research, Queen’s Medical Research Institute, University of Edinburgh, United Kingdom.

3Department of Orthopaedic and Trauma Surgery, University of Edinburgh, United Kingdom.

 

ABSTRACT:

Objective: Articular cartilage may experience iatrogenic injury during routine orthopaedic/arthroscopic procedures. This could cause chondrocyte death, leading to cartilage degeneration and posttraumatic osteoarthritis. In an in vitro cartilage injury model, chondrocyte death was reduced by increasing the osmolarity of normal saline (NS), the most commonly-used irrigation solution. Here, we studied the effect of hyperosmolar saline (HS) on chondrocyte viability and cartilage repair in an in vivo injury model.

Design: Cartilage injury was induced by a single scalpel cut along the patellar groove of 8 week old rats in the absence of irrigation or with either NS (300 mOsm) or HS (600 mOsm). The percentage of cell death (PCD) within the injured area was assessed using confocal microscopy. Repair from injury was evaluated by histology/immunostaining, and inflammatory response by histology, cytokine array analysis and ELISA (enzyme-linked immunosorbent assay).

Results: The PCD in saline-irrigated joints was increased compared to non-irrigated (NI) joints [PCD=20.8% (95%CI; 14.5, 27.1); PCD=9.14% (95%CI; 6.3, 11.9); P=0.0017]. However, hyperosmotic saline reduced chondrocyte death compared to NS (PCD=10.4% (95%CI; 8.5, 12.3) P=0.0024). Repair score, type II collagen and aggrecan levels, and injury width, were significantly improved with hyperosmotic compared to NS. Mild synovitis and similar changes in serum cytokine profile occurred in all operated joints irrespective of experimental group.

Conclusions: Hyperosmotic saline significantly reduced the chondrocyte death associated with scalpel-induced injury and enhanced cartilage repair. This irrigation solution might be useful as a simple chondroprotective strategy and may also reduce unintentional cartilage injury during articular reconstructive surgery and promote integrative cartilage repair, thereby reducing the risk of posttraumatic osteoarthritis.

 

SUPPLEMENT:

A new ‘solution’ for protecting articular cartilage during orthopaedic surgery.

Contact: Andrew C. Hall, Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh. Email: a.hall@ed.ac.uk

 

The problem of osteoarthritis.

Articular cartilage is an extraordinary tissue situated at the ends of the bones, which is essential for the almost friction-free movement of our joints over many decades. Cartilage is maintained throughout life by cells called chondrocytes but if they are damaged or die they are not replaced. This means that these cartilage areas may become weakened and worn away potentially leading to the development of osteoarthritis (OA). OA is the most common musculoskeletal condition and around a third of people aged 45 years or over in the U.K. (a total of 8.75 million people) have sought treatment for OA [Arthritis Research (UK)]. OA can affect any joint in the body but especially the weight-bearing joints of the lower limbs such as the hip, knee and ankle. It causes significant disability due to pain and limitation of joint movement. There is no cure, and ultimately the only treatment is joint replacement which is expensive and may only last 10-15 years. With the ageing population, OA will become an increasingly common disorder and will reduce the quality of life for many, and put a greater strain on carers and the Health service. It is therefore very important that chondrocyte damage and death is minimised so as to preserve our healthy cartilage for as long as possible.

 

Cartilage injury during orthopaedic surgery?

During orthopaedic procedures, joints are normally rinsed with a saline solution thus improving visibility for the surgeon. However, this solution has a totally different composition compared to synovial fluid which normally bathes cartilage. Throughout the operation, the tissues of the joint may be damaged either accidentally (e.g. by scraping, bumping) or deliberately (e.g. trimming/cutting/drilling) using standard orthopaedic surgical apparatus. Some time ago we showed that chondrocytes are sensitive to mechanical injuries, for example, when cartilage is cut with a fresh scalpel blade this causes a band of cell death1. We discovered that by raising the osmotic pressure of the saline (by simply adding sugar to saline), we could protect the cells against mechanical injury so that chondrocyte death along the cut was dramatically reduced. This solution is described as chondroprotective because it protects the chondrocytes against mechanical injury.

 

What were the key findings of our research?

In the present work funded by Arthritis Research (UK) http://www.arthritisresearchuk.org/ (Eltawil et al., 2015), we have extended this project and performed a very small scalpel cut in the articular cartilage of living anaesthetised animals under the following conditions, (a) without saline irrigation, (b) in the presence of normal saline irrigation or (c) in the presence of our special chondroprotective solution. We have then studied the subsequent changes in cartilage and found that there was significantly GREATER chondrocyte death when the saline solution was used, compared to no irrigation, or with the chondroprotective solution. Furthermore, we have noted that there is evidence of IMPROVED repair to the injured cartilage when the chondroprotective solution was used compared to the other conditions. There is therefore less damage to chondrocytes and better cartilage repair when the chondroprotective solution was used compared to the saline currently used in orthopaedic surgery. In order to evaluate the solution for possible clinical use, we have also investigated whether there was a difference in the inflammatory response of the joint under these three conditions, but have found that they are indistinguishable.

 

What is the significance of the work?

Our research suggests that the amount of chondrocyte death that occurs either accidentally or by design in orthopaedic operations may be markedly reduced if joints are irrigated with our chondroprotective solution during surgery. In addition, cartilage repair appears to be more effective when the chondroprotective solution is used. This simple and cheap solution would reduce the extent of any chondrocyte death and enhance repair of any damage, thereby protecting the joint against the development of OA.

 

Reference:

  1. Amin, A.K., Bush, P.G., Huntley, J.S., Simpson, A.H.W. & Hall, A.C. (2008). Osmolarity influences chondrocyte death in wounded articular cartilage. Bone Jt. Surg. (Amer). 90, 1531-1542.

 

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