The following is an article that Dr. Kleider wrote on the injection of bone marrow (Stem Cells). This same technique is used to inject other tendon and ligament areas as well.
How to Obtain and Inject Bone Marrow into Standing Horses affected with Proximal Suspensory Desmitis
Nicholas Kleider, DVM
Intralesional injection of bone marrow is a relatively new treatment for proximal suspensory desmitis (PSD). This paper describes the technique in the standing horse. Authors' address: Kleider Veterinary Services, 8036 232nd St., Langley, B.C., Canada V1M 3R8.
Injection of bone marrow under general anesthesia for the treatment of PSD has been described.1 The ability to offer this form of therapy in the standing horse has many benefits. Avoiding general anesthesia means a reduction in the total time for the procedure and decreased anesthetic risk. This translates into increased owner acceptance of the procedure and greater availability for more veterinarians to treat affected horses with this technique.
Materials and Methods
Sedation for clipping: Detomidine HCLa at .005 -.01 mg/kg IV is administered according to temperament.
Clipping & scrubbing: The involved limb is prepped from mid radius or proximal tibia to proximal fetlock. The ventral sternum area is clipped along the midline cranially from between the limbs, caudally to behind an imaginary girth.
Sedation for the procedure: A combination of detomidine HCL at .005 - .01 mg/kg IV and butorphanol tartrateb at .01 mg/kg IV is administered according to temperament.
A sterile field is prepared and all necessary materials are laid out (Fig. 1)
For forelimb PSD the ulnar nerve is anesthetised (Fig. 2) and for added assurance the lateral palmar nerve may also be blocked (Fig. 3).
For hind limb PSD the tibial nerve is desensitized a hand's breadth above the point of the hock. The limb is flexed to enhance palpation and 20 ml mepivacainec is infiltrated through a 1.5 inch, 20-gauge needle.
Sternum: The acquisition site is on the midline several (2-4) centimeters caudal to a line drawn between the points of the elbow. 10 ml mepivacaine is infused through a 3.5-inch 18-gauge needle as it is inserted up to the sternum staying absolutely on the ventral midline and perpendicular to the ground. (Fig.4). This is facilitated by an assistant monitoring needle placement. An additional few milliliters of anesthetic is deposited onto the sternum and the needle removed.
A small stab incision is made with a #15 scalpel blade. A bone marrow needled is inserted through the anesthetized region and directed in the same plane until contacting the sternum. The needle is then directed through the outer rather soft cortex of the sternebra by a forward and backward twisting motion with controlled steady upward pressure while remaining on the ventral midline and staying perpendicular to the ground. Once the needle feels firmly embedded (approximately 1 - 1.5 cm within the bone) the stylet is removed and a 35 ml sterile empty syringe is attached. A sample with a higher stromal marrow content and less blood contamination is ideal. This is obtained by creating suction through rapid and repeated withdrawal of the plunger (Fig 5). Approximately 20 - 30 ml of marrow is collected, the syringe is disconnected from the bone marrow needle and the needle is withdrawn. Any excess air is expelled from the syringe and an 18-gauge needle is applied in preparation for intralesional injection.
The previously scrubbed and anesthetized limb is flexed. The overlying flexor tendons are pushed to the side allowing the operator to insert the needle into the middle of the affected area from either a medial or lateral skin entry (Fig 6). In order to limit the number of skin punctures the operator injects 2 ml aliquots of bone marrow by fanning them through the injured area. This is done by withdrawing from the ligament and reinserting without withdrawing the needle from the skin. If the area requiring treatment is extensive than additional skin entries are made and the procedure repeated.
If the time from marrow acquisition to marrow injection is immediate than clotting within the syringe is minimal and there appears to be no need to divide the marrow into smaller syringes.
The injected area is routinely bandaged in a sterile dressing and the sternal incision is closed with a skin staplee.
Postoperative protocol includes stall rest and NSAID therapy for 5 days. The surgical bandage is removed the following day and replaced with a thick support wrap. This is changed daily and kept in place for one month to minimize swelling.
We have 6-month follow-ups on 8 horses treated this way since August of 2000. Six were affected with forelimb PSD and 2 with hind limb PSD. All of the cases were chronic or resistant to normal therapy. Blocks and sonographs were used to diagnose the injuries. Of the forelimb cases 1 is actively competing as a jumper, another as a dressage horse, 1 died in a highway accident and 2 were vetted on prepurchase exams and successfully sold. One of the forelimb cases, a TB racehorse was not completely sound at 3 months post injection and subsequently was still lame in the same limb a year later. The lameness did not block out and the horse was referred to another institution for nuclear scintigraphy and repeat workup. No diagnosis was made. One hind limb PSD resolved while the other remained lame.
Our total PSD caseload for the period of time since starting the technique was 41. We routinely institute a controlled exercise program, which results in a positive outcome in approximately 80% of our caseload. The cases still lame at 3 months post initial exam were retired or proceeded with alternative therapy such as bone marrow injections.
Chronic and unresponsive PSD cases are frustrating for both owner and clinician. Bone marrow injection seems to provide a glimmer of hope at the end of a dark tunnel.
It is important that a proper rehabilitation program be instituted after therapy. We insist on stall rest and hand walking only for 2 months post injection. At 2 months the horse is reevaluated clinically and with ultrasound. The horse is sedated with acepromazinef according to temperament and longed at the trot in both directions on soft ground. If sound than the horse can begin a walk-trot rehab program. We ensure that the horse's feet are properly balanced and prefer the horse does straight-line "road work" versus work in a deep going that consists of many turns. Light sedation with acepromazinef, or some of the longer lasting hypnotics is useful to ensure strict compliance. Horses that break out of their stalls or gallop madly away from their caretakers will destroy all the newly forming collagen fibers. Race horses or horses too hot to ride in a slow and controlled manner are recommended to a "Dutch Walker" or merely given a larger stall.
Reevaluation is done prior to soft groundwork and cantering. Most horses are finished their program by 6- 8 months post injection and resume full work at this time.
During the acquisition of the bone marrow it is helpful to have an assistant positioned in front of the horse. Placement of the biopsy needle perpendicular to the ground and not straying from the midline is aided by the assistants' helpful directional comments. This helps avoid iatrogenic complications such as cardiac puncture. Sonographic evaluation of the sternal puncture site instills operator familiarity of the anatomy of the region and allows measurement of the skin to sternal distance (Fig.7,8,9,10).
Rarely, if upon aspiration bone marrow cannot be obtained than the operator is outside the marrow space. If too superficial than replacement of the stylet and a few additional upward twists should resolve the problem. If this fails than the needle may be in between sternebrae. Correction requires a fresh approach, cranial or caudal to the first, after repeating appropriate anesthesia.
It is important that no heparin or other anticoagulant be used for collection of the bone marrow. This results in bleeding and excessive hematoma formation at the injection sight.
Over sedation should be avoided since it makes lifting and flexion of the limb to be injected difficult.
When injecting a hind limb it is helpful to have assistants lift and flex the limb. The operator has more freedom to inject the suspensory from the inside with a medial approach taking advantage of the relatively smaller diameter of MT2.
Sonographic guidance is not used for the injection but utilizing the fanning technique ensures that sufficient bone marrow is deposited. Unless the area is fibrosed it is common for disrupted areas to have little resistance to the injection procedure. If there is great resistance to the injection than the needle is within healthy or fibrotic tissue. There appears to be less postoperative swelling and less chance of infection by fanning the needle in and out of the ligament as opposed to continual reentry through the skin.
A potential complication is injection of bone marrow into the palmar pouches of the carpometacarpal joint. This is a concern since an insertional desmopathy requires injection adjacent to the joint. By fanning small amounts the inadvertent injection of any bone marrow is limited in volume and to date there have been no untoward affects noted.
The owners are warned that a certain amount of post-operative swelling is expected and this will normally diminish with time (Fig. 11). Bone marrow is naturally more resistant to infection so pain or fever is not a normal complication.
Our results are favorable considering the poor prognosis reserved for chronic or unresponsive cases. The ability to utilize this technique without a general anesthetic makes the procedure available for more horses. We speculate that offering this technique as part of initial therapy and combining it with a strict rehabilitation program will result in a better prognosis for horses affected with PSD.
References and Notes
1.Herthel DJ. Enhanced Suspensory Ligament Healing in 100 Horses by Stem Cells and Other Bone Marrow Components, in Proceedings. Amer Assoc Equine Practnr 2001:319-321.
a Dormosedan Orion Corporation, Espoo, Finland.
The author is grateful to Dr. Allan Nixon for initially introducing him to the technique.