Orthobiologics is the use of autologous blood to treat pain and tissue damage. This is primarily done using platelet rich plasma (PRP) and bone marrow aspirate concentrate (BMAC). Even though the concept has been around for decades, there have been more advances over the past five to ten years in standardizing the use of this medicine for musculoskeletal issues.
The goal of orthobiologic injections such as Platelet Rich Plasma (PRP) and Bone Marrow Aspirate Concentrate (BMAC) are to augment the body’s normal response to tissue injury. On a large scale, one needs to have a firm understanding of the tissue injury cycle, which is made up of 4 phases. These phases are: hemostasis, inflammation, proliferation and remodeling. The next step is to understand the biochemistry of each phase. Creating an environment to improve pain reduction and tissue healing starts with learning about the specific cells that are signaled to respond in addition to the cascades or response to introducing these cells to the injured area.
Although growing and regenerating tissue sounds like mad science, the studies, research and techniques are becoming more standardized. Unfortunately, as of the time of writing this article, utilizing orthobiologics is not a guarantee for every patient to see a positive response. This is because there are other factors that affect healing of the damaged tissue. This includes the extent of tissue damage, patient genetics and pre-existing health conditions, environmental exposures (smoking, diet) and psychosocial expectations. Outcomes are also affected by quality of blood draw and processing, understanding of which orthobiologic to utilize for optimal outcomes, and provider technique and dosing for injecting into and around the damaged areas.
In this article, I would like to provide an overview of the tissue injury cycle which will help patients understand the expectations and proper healing environment to create superior outcomes after their PRP or BMAC injection. This can allow the previously damaged tissue to withstand daily physiologic forces and stresses in addition to functional demands of recreational/sporting activities.
It is important to understand that different types of tissue require different healing times. Below I outline average healing times based on the type of tissue damaged (ie. tendon, ligament, joint, muscle). Again, it is important to understand that each person’s healing times are different based on the extent of tissue damage, patient genetics, pre-existing health conditions, environmental exposures (smoking, diet) and psychosocial expectations.
The tissue injury cycle is made up for the four phases after injury:
1. Hemostasis Phase (0-7 days)
· Platelets
2. Acute Inflammatory Phase (8-21 days)
· Granulocytes
3. Proliferation Phase (3-6 weeks)
· Monocyte/Macrophage
4. Remodeling Phase (6-15 weeks)
· Fibroblasts
Average Healing Times
Joint >4-8 wk
Muscle Belly >6-8 wk
Ligament* >10-12 wk
Tendon >11-15 wk
*Ligament healing may be delayed 2-4 wk and should avoid valgus/varus stress to optimize recovery times.
Understanding the duration of these phases and the processes that occur during each will help shape and understand the appropriate exercise and return to normal activity. Below is an outline of the basic principles of rehabilitation progression timelines and expectations following orthobiologic injections. By utilizing a proper dosed exercise program, we can enhance the success of these injections to heal our tissues and create a better outcome for patients.
Pre-injection: Prehab
I think it is important to include some pre-injection education. Prehab includes the initial assessment of the injured area. The importance of this step is assess the areas around the injured site in addition to the affected area. Limitations in mobility, function, strength can give better guidance to post-injection rehabilitation.
The clinician may recommend some initial mobilization, strength and stretching exercises for the surrounding areas to improve outcomes. An example of this could include the hip for gluteal activation and strengthening in addition to ankle mobilizations for someone with a patellar tendon injury. This should be evaluated and discussed by the clinician and patient prior to the injection.
Some other general guidelines to optimize outcomes include avoiding NSAIDs at least 2-3 weeks prior to injections and providing patients with a general expectation of the healing process.
**There is no absolute progression between phases, and there can be variability between each individual patient and their respected outcomes**
Phase I: 0-7 days post-injection
The first week post-injection is focused on protecting the area injected and allowing the initial inflammation to occur to start the healing cascade. In the first week, the patient should avoid any excessive loading to the joint. They can resume daily activities as tolerated, however. This helps minimize stress at the injection site in addition to activating the PRP to prepare for cross bridging.
General Recommendations/Restrictions:
· Avoid stressing joint/ligament/tendon (esp. rotation, valgus/varus)
· LE: limit weight bearing; UE: no lifting
· Continue to avoid NSAIDs
· Use heat 4x/day x 15mins
· Tylenol PRN
Phase II: 1-2 weeks post-injection
This phase is focused on facilitating collagen deposition and trying to avoid any disruption in collagen cross-linking. This is vital to having a well-organized structure to rebuild the injury site. Patients should continue to minimize stress on the injection site to allow for proper cross-bridging.
General Recommendations/Restrictions:
· Avoid stressing joint/ligament/tendon (esp. rotation, valgus/varus)
· Continue to avoid NSAIDs
· Use heat 4x/day x 15mins
· Tylenol PRN
· Progress AROM to >90% full ROM by the end of week 2
· Patients may progress to full weight bearing (LE), and lifting no more than a dinner plate (UE)
Phase III: 3-6 weeks post-injection
The goal of phase III is to continue to protect the injected tissue, but start to transition to exercises that will be helpful to facilitating collagen deposition while maintaining proper collagen cross-linking. At this point, pain should be significantly reduced, allowing the patient to participate more actively in loading and training the area. The tissue will start to be able to withstand more tensile loading. In addition, utilizing soft tissue mobilization, Blood Flow Restriction (BFR) and low weight-high repetition concentric loading will facilitate the healing mechanism and proper fiber alignment. Cardiovascular training is also important to improve patients endurance and tissue repair.
General Recommendations/Restrictions:
· Avoid stressing ligaments still (esp. rotation, valgus/varus) until week 7
· Avoid compressive/torsional loading on articular cartilage until week 5 or 6
· Can use NSAIDs, if necessary
· Use high-repetition, low-load concentric exercises for muscle/tendon and use cyclical high-volume compression-decompression for cartilage/joint
· Initiate CV exercise to improve tissue vascularity and joint synovialization
o UE procedure = LE cardiovascular exercise
o LE procedure = UE cardiovascular exercise
Physical Therapy Exercise Progression Key Points:
· Pain should not increase by >2 points on VAS
· Utilize manual therapy along tissue fibers (Graston, Soft-tissue mobilization, ESTIM)
· ROM, optimize isometrics at comfortable “end ranges” +/- BFR for improved vascularity/enhanced outcomes
· Utilize aquatics, treadmill, elliptical for CV endurance training
· Once concentric strength is improving, start trialing eccentric loading (low weight, high rep)
· Neuromuscular Rehab (PNF, proprioception)
Phase IV: 6-15 weeks post-injection
This phase is the last piece of the puzzle, or, putting it all together. Here, the goal is to restore normal tissue integrity and fiber alignment, maximize tissue vascularity and synovialization, increase tissue tensile strength, improve joint proprioception and elasticity. Here, the patient should notice a difference in improved strength of the repaired tissue through improved ability to produce force, withstand tensile forces, and overall pain reduction. Although results may not be perfect at this time, they should be fairly noticeable.
**If no results by week 6 or 7, there may be a need for additional injection versus surgical consultation should be considered**
General Recommendations/Restrictions:
· Consider follow up US to evaluate tendon repair
· Continue soft-tissue modalities to increase tissue vascularization and break up any tissue adhesions
· Progress to functional mobility exercises (squats, lunges, push-ups)
· Progress eccentric training
· Progress plyometric loading from less than BW to full body weight AND from bilateral to single (ie. Box jumps, jump rope, scissor squats)
o By week 8-10, should start to train fast-twitch and dynamic exercises more aggressively (pending patient response by week 6-7)
· For Athletes:
o Week 8: 50% return to sport
o Week 10: 75% return to sport
o Week 12: 90% return to sport
o *after week 10, can consider return to sport 100%
· Continue proprioception and balance training with unstable surfaces (ie tilt-board, overhead KB carry)
Closing Thoughts:
It should be noted that these are general guidelines, and that each individual healing time will be different based on location and extent of injury, genetic and pre-existing health conditions. For PRP injections, patients can generally assume to return to full functional sporting/recreational activities by 10-12 weeks post injection. You should be back to regular activities of daily living by weeks 3-6.
Again, I stress that there is no absolute progression between phases, and there can be variability between each individual patient and their respected outcomes. That being said, if there is absolutely no improvement by week 6 or 7, an additional injection versus surgical consultation should be considered.
For more information about tissue injury and rehabilitation, check out this blog post.
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