Tendon and ligament injuries have traditionally been treated with rest. In the past horses have been turned away for up to 18 months to allow these injuries to heal. The problem is that they generally heal with scar tissue which is neither flexible nor particularly strong leading to a high injury recurrence rate when the horse is returned to athletic work. More recent research has indicated that better results are obtained from combining box rest with an early return to controlled exercise – starting as early as a week post-injury with 10mins hand walking and gradually increasing this until the horse is back in full competition-level work about 9 months post-injury. Obviously re-scanning regularly during this period helps to determine whether the healing is progressing as hoped and when it is safe to step the exercise up a level.
Recently several new treatments have become popular for the treatment of tendon and ligament injuries. These are aimed either at accelerating the speed of healing or improving the quality of the tissue being produced in the damaged area.
Stem Cell Treatment
Stem cells are multipotent cells found primarily in bone marrow. They are like basic building blocks which have the ability to differentiate and become specialised cells such as those found in tendons, ligaments, bones and cartilage.
Stem cells are usually harvested from the sternum (between the front legs in the girth area) or the tuber coxae (point of hip). This can be done under standing sedation. The sample is then sent off to a lab where the stem cells are extracted from the bone marrow and multiplied until there are several million of them. This usually takes 2-3 weeks after which they are returned to the vet.
They are re-implanted into the horse in the area which has been injured eg. into the centre of a superficial digital flexor tendon (SDFT) core lesion. This is done, again under standing sedation, using ultrasound guidance to ensure the cells are accurately implanted into the exact location where they are required.
The beauty of stem cell treatment is it means that the tissue heals with flexible tendon cells, rather than brittle scar tissue, which means that there is a much better quality of healing and lower risk of re-injury.
Stem cell treatment is suitable for superficial and deep flexor tendon injuries, some ligament injuries (eg. suspensories) and is sometimes used to assist fracture repair.
There are some notable, and well publicised, success stories with this treatment. Examples include national hunt star Dream Alliance who injured a tendon during the 2008 Grand National but following treatment went on to win the Welsh National. In the eventing world Nici Wilson’s horse Oingy Boingy won a medal at the 2007 Young Rider Europeans and subsequently jumped double clear at 4* level following treatment.
PRP (Platelet Rich Plasma) Treatment
Platelets are involved in clotting and wound healing. They contain a number of growth factors which help in the formation of connective tissue, new blood vessels, skin etc.
A blood sample is taken from the horse which is then processed to remove the unrequired blood cells leaving plasma with a concentrated proportion of platelets. This is then injected into the affected area under ultrasound guidance in the same manner as stem cell treatment. The defect is still healed using connective tissue, rather than differentiated tendon or ligament cells, but the healing process is accelerated and assisted by the growth factors derived from the platelets.
PRP is commonly used in the treatment of SDFT and DDFT injuries, suspensory injuries, joint injuries where there is cartilage damage, wounds that won’t heal and corneal ulcers.
PRP is also used by human elite athletes – both Tiger Woods and Rafael Nadal have been treated for knee ligament injuries by this method.
Shockwave is a non-invasive therapy which sends high-energy sound waves through tissues. These increase in pressure as they travel through the area being treated. The method by which this promotes healing is not clear, although it is postulated that it stretches cells in the injured area, stimulating repair.
The machine is portable and usually treatment consists of three courses of 500-1500 shocks being given at 1-2 week intervals.
It is advisable only to use it after the inflammatory reaction associated with the original injury has settled down and the injury has started the healing phase as it is possible to aggravate the injury further if used too soon. There are no official guidelines for FEI sport but it is not supposed to be used within the 48hrs before a horse races so we usually take that as a yardstick.
Shockwave is most commonly used in the treatment of suspensory (both main body and branch) injuries, sacro-iliac problems, back pain and some splints.
As you can see there are a lot more treatment options available following tendon or ligament injury than there were even ten years ago. Such injuries can still be career-ending but the success rates are gradually improving. As always scientific advancement comes at a price and most of the horses that get treated are the insured ones or the valuable ones. However if we want our horses to return to their full athletic ability we now know that whilst time remains a great healer, we need to be a lot more proactive than simply turning them away and forgetting about them for a year.