It is becoming increasingly apparent that while extended crate or stable rest protocols for musculoskeletal injuries or post-operative recovery are still widely recommended, the standard of care has shifted away from extended immobilisation towards early mobilisation and weight bearing. It can, however, be very challenging to change the perspective and recommendations of Veterinary professionals from rest to early mobilisation.
During several lectures in 2021, the detrimental effects of extended rest and immobilisation were highlighted. Here we discuss taking a more active approach with earlier mobilisation and loading of healing tissues from an evidence-based perspective.
If you have been looking for the evidence behind the earlier mobilisation protocols and theories, we are happy to share a few below.
Healing phases and timelines
During the Vet Rehab Summit 2021, Dr Sheila Schils shared that we are revising our understanding of the tissue healing timelines and how we interact with them. The healing timelines may be up to 50% faster than we initially thought in the 90s.
In the same lecture, Dr Lowri highlighted that the timeline is also not static – tissues will cycle through the inflammatory, reparation and maturation phases many times through the course of healing, and this is something that we can strongly influence with our rehabilitation protocols. Inflammation is not the enemy of healing, but rather allows the body to continue to break down tissue that is incorrectly aligned or that causes scarring and restrictions in motion, and replace it with functionally appropriate collagen fibrils.
Dr Lowri follows a three-day protocol to guide tendon and ligament healing, where on day 1 (not day 1 post-injury, but rather day 1 of the rehabilitation protocol) she will use overload and cause microdamage to the tissue, putting the tissue into a negative balance; on day 2 the tissue will again reach a neutral point, on day 3 there will be adaptative collagen deposits before the 3-day cycle repeats.
The art and science of rehabilitation
How does this understanding impact our approach to different tissues with different healing timelines?
Having a thorough working knowledge of healing timelines for different tissues, as well as an anatomical understanding of the involved structures, remains essential. A biomechanical understanding of the load and strain placed on tissues during specific movements, gaits and exercises provide additional essential information as we clinically reason how much overload to apply – we may need simple toe-touch weight bearing, weight shifting or a leg lift to start with – and how best to apply it to the affected tissue. From that point onwards, rehabilitation becomes an art form, as science cannot guide us all the way at this point. In fact, science may never be able to guide us through individual variations in biomechanics, tissue healing and preference.
Detrimental effects of immobilisation
We now have a far better understanding than in earlier years of the detrimental effects of immobilisation on the entire body, systemically and locally, as highlighted in a previous blog and webinar. Since many of our patients are already leading a sedentary lifestyle before injury, they will probably already be experiencing some of the detrimental effects of lack of exercise, which may include
- poor cardiovascular capacity,
- lack of muscle mass and strength,
- lack of muscular endurance,
- compromised joint health,
- reduced bone density,
- increased pain perception,
- increased inflammatory markers,
- mental or behavioural adaptations such as depression or anxiety.
These factors affect our patients on every level, including their ability to effectively heal, their pain experience, and the level of inflammation occurring within their bodies. Additional extended periods of rest in a patient that is already sedentary may lead to a worsening of the above factors, as well as sub-optimal healing of the injury or operated site, sub-optimal return to function, and a higher risk of re-injury of the initial injury or breakdown of a new site or area.
Tendon and ligament healing
With most injuries or conditions, the period of rest or immobilisation remains relatively short and the negative effects can usually be countered with a rehabilitation and exercise protocol, leading to successful rehabilitation and return to function in the majority of cases, with minimal complications. When it comes to the rehabilitation of tendon and ligament injuries, results are much more varied; rest periods are often prolonged, and recovery with a return to sport or function is far less certain.
With a 12+ month healing timeline, what should our rehabilitative timeline look like, and more importantly, what kind of activity should be undertaken and at what point of the rehabilitation?
Bring et al. (2010) compared mobilisation and immobilisation of Achilles tendon ruptures in rat models, and found that after eight days, mRNA levels were comparable between the two groups, but that by day 17, the mRNA levels for brain-derived neurotrophic factor (BDNF), basic fibroblast growth factor (bFGF), cyclooxygenase 1 (COX 1) and hypoxia-inducible factor-1α (HIF-1α) in the mobilised group had increased significantly. Corresponding mRNA levels in the immobilised group decreased during the same period.
‘This study supports the notion that prolonged immobilization post-rupture hampers the healing process by compromising the up-regulation of repair gene expression in the healing tendon. It might be speculated that a shorter period of immobilization, i.e. 1 week, would not impair the healing process significantly. The findings support the current development of earlier and more active rehabilitation programs after tendon injuries.’
Amiel et al. (1991) looked at the healing tendons of 40 adult dogs, comparing mobilisation post-rupture to immobilisation. They found that early immobilisation depresses the accumulation of tissue fibronectin during the initial stages of healing (up to 17 days), and recommended early mobilisation.
In contrast, Gimbel et al. (2007) compared different levels of activity post-supraspinatus tendon rupture and repair in rats. They compared shoulder immobilisation to cage rest and moderate exercise over a period of four or sixteen weeks. They found that activity levels had no effect on the elastic properties of the insertion site at four weeks post-injury, and that decreased activity had a positive effect on these properties at sixteen weeks. This study suggests that decreased activity through immobilisation improves tendon healing at the site of insertion, progressing by first increasing the organisation of the collagen and then increasing the mechanical properties.
Bakti et al. (2019) concluded that in the case of rotator cuff tears in people, early mobilisation carried a higher risk of re-injury while a delayed range of motion – or immobilisation – for up to six weeks resulted in improved patient outcome measures and a lower risk of re-injury.
If we consider the available literature on supraspinatus/biceps tendon injuries in canines, Canapp et al. (2016) comes to mind, where a retrospective study of 327 dogs with these diagnoses was performed. Rest and mobilisation were not factors evaluated in this paper.
So where does that leave us when it comes to tendon and ligament rehabilitation in our canine or equine patients? Equine tendon injuries are commonly treated with stable rest and a hand walking protocol that progresses every 30 days, but there are more and more practitioners who are incorporating a more thorough or extensive early exercise regimen – we just don’t have the data on these protocols yet.
Points to note and highlight from the Vet Rehab Summit
During the Vet Rehab Summit 2021, Lowri Davies and Sheila Schils dove into the complex topic of isolated and integrated exercise, with rest and earlier exercise protocols being one of the topics that generated a great deal of interest and discussion. I would love to highlight some of the thoughts shared by these lecturers that really stood out for me.
Dr Lowri recommends following a three-day progression protocol in the rehabilitation of ligament and tendon injuries, as described in the first section of this blog. She uses a plyometric overload of the tendons every third day to achieve that overload and recommends that we move away from thinking of the inflammatory, reparative and remodelling phases as being static, and rather consider them as dynamic processes that we can influence through rehabilitation.
Dr Sheila highlights that we cannot be afraid of or shy away from pain in our patients – if our patients do not experience some discomfort during exercise, we won’t be able to help them progress. When we initiate a mild inflammatory response it is a call for celebration, as we have achieved microdamage and can progress the healing and change the tissue. Whether we adapt the tissue for better or worse will depend on our knowledge, skill and clinical reasoning abilities.
Dr Lowri further states that we would manage acute and chronic pain very differently, as acute pain mirrors tissue damage while chronic pain is divorced from tissue damage.
When answering the question, ‘Do we exercise or do we rest?’ Dr Sheila states:
‘Rest is not the first choice, rest is the last choice. We think of rest as the safer protocol, when it is far more likely the most unsafe protocol. What I like to say to my clients is that if their horse is so fragile that they have to stand in their stall for six months, then maybe they are just too fragile to rehab and they may be done with their career. When we treat the tissue as if it is fragile, it will be fragile. If we treat the tissue such that it is dynamic and strong, and we expect it to be dynamic and strong, it will heal that way. Healing in a static environment leads to static healing, healing in a dynamic environment leads to dynamic healing.’
In a recent podcast by Gillian Tabor, ‘Milestones NOT timeframes’, Gillian highlights how we can move away from a ‘static’ understanding of healing timelines to rather evaluate progress in accordance with milestones reached, which correlates well with the above discussion. Progression in rehabilitation should be made according to the achievement of milestones or rehabilitation goals by the individual patient.
As a relatively conservative Vetrehabber who likes to play it safe when it comes to the treatment and rehabilitation protocols I implement, the above information still leaves me with many questions. When should activity start, what kind of activity should we start with, and to which conditions or kinds of injuries does early mobilisation apply? The research above clearly shows that in the case of some injuries, early mobilisation was not beneficial and increased the risk of re-injury.
Taking into account the above information, together with that gathered over the last year of CPD lectures, the following will be how I adjust my approach to treating patients:
- incorporating static weight-bearing exercises as early in rehabilitation as the patient is able;
- incorporating the three-day overload principle, where mild overload can be applied every third day, with variations to the target tissue or the means of overload to prevent repetitive overload or strain; and
- preventing immobilisation of the entire body, by continuing to challenge and exercise the healthy and uninjured structures.
When we speak about the early mobilisation of injured or post-operative structures in conversation with veterinarians or surgeons, it may be useful to discuss not only the negative impact of immobilisation but also what exactly early mobilisation or activity means. It does not mean an application of the same stressors or loads as we would apply at three or six weeks post-injury or surgery, but a very gradual mobilisation and introduction of load that will help guide the inflammatory, reparative and remodelling phases to optimally heal the affected tissues, while preventing the detrimental effects of immobilisation on all the body systems of the patient.
Amiel, D., Gelberman, R, Harwood, R., Harwood F. (1991). Fibronectin in healing flexor tendons subjected to immobilization or early controlled passive motion. Scandinavian Journal of Medicine & Science in Sports 11 (3): 184-189
Bakti N., Antonios, T., Phadke, A. & Singh, B. (2019). Early versus delayed mobilization following rotator cuff repair. J of Clin Ortho and Trauma.
Bring, C., Reno, P., Renstrom, P., Salo, D., Hart, P. & Ackermann.P. (2007). Prolonged immobilization compromises up-regulation of repair genes after tendon rupture in a rat model. Scan J. Med Sci Sports, 20 (3): 411-417.
Canapp, S.O., Canapp, D.A., Carr,B.J., Cox, C. & Barrett, J.G. (2016). Supraspinatus tendinopathy in 327 dogs: A retrospective study. Veterinary Evidence Vol 1 No 3
Gimbel, J.A., Van Kleunen, J.P., Williams, G.R., Thomopoulos, S. & Soslowsky, l.J. (2007). Long durations of immobilization in the rat result in enhanced mechanical properties of the healing supraspinatus tendon insertion site. Journal of Biomechanical Engineering, 129(3):400-4Jung H.J., Fisher M.B. & Woo, S.L.Y. (2009). Role of biomechanics in the understanding of normal, injured and healing ligaments and tendons. Sports Medicine, Arthroscopy, Rehabilitation Therapy & Technology, 1 (9): 1758-2555.
Kannus, P. (2000). Immobilization or early mobilization after an acute soft-tissue injury? Physician and Sportsmedicine, 28 (3): 55-63.
Schils, S.J. (2017). The development of training programs to reduce injury and of specific rehabilitation protocols when inury occurs. 13th Annual Promoting Excellence Symposium (2017). Florida Association of Equine Practitioners, Proceedings October 19-22, Naples, Florida.
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