The scenario of horses undergoing prolonged periods of stall rest due to soft tissue injuries is a common sight. However, it is intriguing to note that such a rehabilitation approach, prevalent in equine medicine, is essentially contraindicated in human medical practices.
Notably, advancements in human medicine have emphasized the importance of early mobilization in soft tissue repair, exemplified by patients undergoing hip replacement surgery who are encouraged to stand within 48 hours post-surgery to foster optimal recovery (Guerra, 2015).
Despite this understanding in human medicine, equine medicine often adheres to outdated protocols, leading to challenges in the complete recovery of horses.
Systematic reviews in human soft tissue injuries have revealed a lack of controlled studies supporting immobilization for soft tissue injuries beyond the acute healing phase.
Surprisingly, this research dates back to 1995, prompting questions about why equine medicine continues to follow obsolete procedures.
The pioneering research in human rehabilitation highlighted the critical role of early intervention post-injury. It emphasized several key aspects to consider when evaluating the effects of immobilization and rest on soft tissue repair beyond the acute healing phase:
Movement Influences Soft Tissue Strength: Studies on dog ligaments have elucidated the pivotal role of movement in determining soft tissue strength, showing that variations in movement levels impact collagen fiber bundle diameters in normal and repaired ligaments and tendons.
Movement Increases Collagen Formation: The degree of movement directly correlates with the number, arrangement, and thickness of collagen fibers in soft tissues, indicating that increased movement generally results in stronger tendons and ligaments.
Effects of Reduced Movement: Diminished loading shifts the balance of matrix turnover, leading to matrix degradation exceeding formation, resulting in less organized and weaker tissues.
Impact of Immobilization on Joint Nutrition and Strength: Prolonged limb immobilization diminishes glycosaminoglycan and water content in soft tissues, reducing their mass, stiffness, and strength, while also disrupting the orientation of collagen fibers, compromising their strength.
Bone-Ligament Junction Vulnerability: Restricted movement or immobilization triggers subperiosteal osteoclasts to resorb the bony inserts of ligaments, weakening the bone-ligament interface and reducing tensile strength and joint stability significantly.
Summary of Research (Buckwalter, 1995):
Injured limbs are traditionally rested by splinting and/or stall rest.
While immobilization of the affected joint has long been prescribed following soft tissue injury, it has since been discovered that healing soft tissues are dramatically affected by the presence or absence of joint motion.
Immobilizing a joint can cause further detrimental side effects, such as synovial adhesions (inside the joint), increased collagen degradation with decreasing collagen synthesis, and a greater percentage of disorganized collagen fibers (scar tissue).
Immobilization causes soft tissue physiology to progressively switch from an anabolic (building up) to a more catabolic (breaking down) state.
Defining Movement
It is essential to clarify that the term "movement" in this context refers to gentle ambulation and physiotherapy-based exercises, not rigorous activities like riding or lunging. These findings underscore the importance of incorporating therapeutic movement in the management of soft tissue injuries in horses to mitigate the adverse effects of prolonged rest.
Which Injuries Involve Soft Tissues?
In short, basically all injuries can affect the soft tissues. Types of soft tissue injuries that the most owners may recognize include; suspensory tear, flexor tendon tear, SI joint subluxatin (hunters bump), windpuffs, OCD, degenerative joint disease (ringbone, sidebone, arthritis), and many more.
Therapeutic Perspective: A Professional's Opinion
Despite these findings, it's common for horses to be prescribed long-term stall rest for soft tissue. This practice raises concerns, given the risks associated with immobilization and reduced movement. It highlights the need for further research and a more nuanced approach to managing soft tissue injuries in horses.
In light of the abundance of data in the human medical realm, the incorporation of controlled movement and integrated therapeutic practice must be applied to optimize recovery, improve longevity, reduce pain, and minimize complications.
References below with inclusion of additional supporting studies below. There is significantly more than what is listed but I will not dedicate additional time towards substantiating what is already out there to be found. If this interests you, I encourage you to explore the research yourself!
References
Buckwalter JA. Activity vs. rest in the treatment of bone, soft tissue and joint injuries. Iowa Orthop J. 1995;15:29-42. PMID: 7634042; PMCID: PMC2329066.
Guerra ML, Singh PJ, Taylor NF. Early mobilization of patients who have had a hip or knee joint replacement reduces length of stay in hospital: a systematic review. Clinical Rehabilitation. 2015;29(9):844-854. doi:10.1177/0269215514558641
Kannus, P. (2000). Immobilization or Early Mobilization After an Acute Soft-Tissue Injury? The Physician and Sportsmedicine, 28(3), 55–63. https://doi.org/10.3810/psm.2000.03.775
AKESON, W. H. M.D.*; AMIEL, D. DIP. ING.**; ABEL, M. F. M.D.†; GARFIN, S. R. M.D.‡; Woo, S. L-Y. PH.D.§. Effects of Immobilization on Joints. Clinical Orthopaedics and Related Research 219():p 28-37, June 1987.
ENNEKING, W. F.; HOROWITZ, MARSHALL. The Intra-Articular Effects of Immobilization on the Human Knee. The Journal of Bone & Joint Surgery 54(5):p 973-985, July 1972.
Ibrahim MS, Twaij H, Giebaly DE, Nizam I, Haddad FS. Enhanced recovery in total hip replacement. Bone Joint J. 2013;95-B(12):1587-1594. doi:10.1302/0301-620X.95B12.31303
Loitz BJ, Zernicke RF, Vailas AC, Kody MH, Meals RA. Effects of short-term immobilization versus continuous passive motion on the biomechanical and biochemical properties of the rabbit tendon. Clin Orthop Relat Res. 1989 Jul;(244):265-71. PMID: 2743669.
Bohm, S., Mersmann, F., Tettke, M., Kraft, M., & Arampatzis, A. (2014). Human Achilles tendon plasticity in response to cyclic strain: effect of rate and duration. Journal of Experimental Biology, 217, 4010 - 4017.
Bunker, T. D., Potter, B., & Barton, N. J. (1989). Continuous passive motion following flexor tendon repair. The Journal of Hand Surgery: British & European Volume, 14(4), 406-411.