Surgical advances for musculoskeletal diseases (Proceedings)

There have been several surgical procedures developed in the last few years to aid in treating musculoskeletal disease in horses. Some of these developments have been due to research findings that have demonstrated improvement in healing of musculoskeletal tissues and advancements in surgical equipment and implants. However, still one of the greatest contribution to surgical advancements has been pain and inflammatory management in joints and tendon sheaths. The goal of this discussion is to review current methods for surgically treating common musculoskeletal diseases in horses.

The philosophy of performing joint surgery has been unchanged in recent years. Osteochondral fragments need to be removed and diseased bone and cartilage debrided adequately. Fractures still need to be repaired and stabilized for horses to have the best prognosis and with some joints arthrodesis is needed in order to stabilize those fractures. Recent advancements in implants have significantly improved the ability to stabilize these repairs. For instance, locking plates are now commonly used for fractures and arthrodesis of joints. In addition to improvement in implants there have been significant improvements in pain management in these horses. Even with severe fractures those that can be adequately stabilized can often times be managed aggressively in order to reduce the chance of laminitis in the contralateral foot. Epidurals using morphine and xylazine and constant rate infusions of lidocaine and ketamine can be used to help manage the pain in those animals. In addition, sling design has been improved in order to help manage those horses.

Today we also better understand how to manage other joint lesions. For instance, we typically debride meniscal lesions and some surgeons justify the use of radiofrequency ablation for stimulating healing in those cases. The same can be said for articular cartilage lesions. Often times we deal with cracked cartilage surfaces or those that have partial thickness erosion. Often times it is best to not fully debride those to subchondral bone and instead those lesions will be lightly debrided or again some surgeons have used radiofrequency probing to enhance healing. The use of radiofrequency probing controversial as it has been shown experimentally to cause chondrocyte necrosis. The justification for its use has been that it shrinks collagen fibers and hence can close some of those smaller cartilage defects. Finally, those horses with osteoarthritis can gain some pain relief through arthroscopic surgery. Joint lavage alone may relieve some pain in those joints and removal of fragments or osteophytes that rise above the joint surface can help.

As important as advancement in surgical techniques have been, advancements in post-operative care have also been helpful. It is common for horses that are operated for joint lesions to go on a protocol of IRAP or Adequan and HA combination post-operatively. Typically we start at the time of suture removal and for both medications usually administer once weekly for three weeks, and then as needed. In addition, we have found that use of stem cells for soft tissue lesions in the joint, such as meniscal lesions, have shown some benefit. We currently recommend the use of bone marrow derived stem cells for this as they have been shown experimentally to have better healing properties than other healing sources.

The navicular bursa has recently become a site of concern in the foot of the horse. Advances in MR imaging have shown that the bursa is commonly a source of pain in the foot and often times it is due to deep flexor tendon fibrillation in that site. Bursoscopy is commonly performed now and can be helpful in debriding those fibrillated fibers and any fibrocartilage damage in the back of the navicular bone.

Tendon and ligament lesions can also be managed surgically. The digital tendon sheath can be scoped if tendon damage has been diagnosed via ultrasound or MRI. Fibrillated fibers can be debrided and core lesions can be decompressed. It is becoming evident that core lesions will often times have a necrotic focus and therefore decompression may be of benefit. Stem cells and various medications have been used to help facilitate healing in these tissues. It is not uncommon to perform annular ligament desmotomy in some of these cases which helps to relieve pain in the area. Superior check ligament desmotomy is now currently performed with an arthroscope. This has the benefit of being less invasive than previous techniques and the area can be visually examined. In addition the superior check ligament can be cut using this technique.

Lastly, management of proximal suspensory desmitis in the hind limbs has been difficult. Even with stem cells and shockwave therapy the results at times have been poor. Therefore it is not uncommon to perform a neurectomy and fasciotomy in the area of the proximal suspensory ligament in order to help facilitate healing and manage pain in these horses. One down side to this technique is that if there is severe damage to the suspensory ligament or mineralization is apparent the surgeon does run the risk of creating a dropped ankle due to further suspensory ligament damage.

Overall surgical advances have helped in our management of musculoskeletal disease in horses and these procedures are performed routinely.