BRINGING SCIENCE TO TREATMENT

Principles of tendon healing apply to the Achilles tendon

Achilles tendinopathy and tear. Photo Credit William Morrison, MD, @morrisonMSK

The principles of tendon injury and healing apply to any injured tendon, even the Achilles. The largest tendon in the body, the Achilles is the connection for both the soleus and gastrocnemius muscle to the calcaneus. It functions in nearly every activity, including walking, running, jumping, and quick starts and stops. Dutch researchers site the incidence of mid-portion tendinopathy at 2.35 per 1000 patients registered in a general practitioner practice, with 35% of those cases associated with sports related activities (1). Interestingly, in a study of 102 Achilles tendons in asymptomatic healthy young subjects (mean age about 27 years old), 16% showed abnormal findings on ultrasound. In yet another example of why therapists should treat the patient and not the test, the clinical presentation of tendon pain does not always correspond with imaging results.

Achilles tendinopathy often occurs in the middle of the tendon, an area known as the watershed zone because of the lack of vascularisation in this region. The decreased blood supply makes the tendon here particularly vulnerable to overload injury. Rehabilitation of Achilles tendon injuries, as put forth by Lachlan Wilmot here, is a four-phase process (see table 1). As discussed prior, this approach should take around 12 weeks to complete. The entire process centers around load management. The acute stage focuses on activating the tendon in a way that doesn’t stretch it, meaning primarily isometrics. Pain 24 hours after activity dictates how well the tendon tolerated a load, and whether the next activation should be a bit more, a bit less, or the same.

Explaining the mechanics of load management to athletes helps with the perception of activity and understanding of healing. Rather than feel that they’ve gone back to ‘baby’ exercises, understanding the different types of tendon loading through different contractions, as discussed by Wilmot here may increase exercise tolerance and acceptance of the rehab process. Tendons can be loaded quite heavily if done using an appropriate method at a suitable time during rehabilitation.

Table 1: 4-phase progression of Achilles tendon loading
PhaseFocusCharacteristicsTime FrameKey Strength ModalityFrequencyPrescription Example
- Phase 1Acute/ProtectivePain/Stiffness upon wakening
Pain on palpation
Pain during activity
Difficulty performing 10 calf raises
0-2 WeeksIsometricsDailySingle leg Isometric Hold (heel off step) – Body weight x 20-40 sec x 3 sets

Progress to loaded holds
- Phase 2Load introductionPain/Stiffness upon wakening
Pain on palpation
Reduced pain during activity
Pain below a 4/10 when perfoming 10 calf raises
2-5 WeeksIsolated Resilience

Controlled Eccentrics
Daily to every second day (the heavier the load, the longer recovery time between sessions)Single Leg Calf Raises (heel off step) x (build up to 20 reps) x 3 sets
Eccentric Heel Lowers (heel off step) – 2 legs up, 1 leg down x 10 reps x 3 sets

Progress to loaded eccentrics and loaded calf raises
- Phase 3Strength AccumilationPain free upon wakening
Reduced pain on palpation
Minimal/zero pain with activity
Can perform 10 loaded calf raises
4-10 WeeksStrength Resilience

Reactive Stiffness
Every 2-3 daysSlow Prowler Push x 20 steps x sets
BB Step Up – Double Box x 6 reps x sets
Mini Tramp Jog x 40 sec ON: 20 sec OFF x 5 sets
Knee Drive Hold on BOSU x 20 sec hold x 4 sets
- Phase 4Elastic TolerancePain free upon wakening
Reduced pain on palpation
Pain free with activity
Jump rope pain free
10+ WeeksReactive Stiffness

Ballistic Stiffness
Every 2-3 daysLinear hop and stick; 6 reps x 4 sets
Lateral hop and stick; 6 reps x 4 sets
Linear hurdle and hop; 6 reps x 3 sets
Lateral hurdle and hop; 6 reps x 3 sets

While progressing exercise to rehabilitate the tendon, its important to remember the entire kinetic chain. Tracy Ward explores the importance of core stabilisation in foot biomechanics here and demonstrates many exercises that can be done without adding additional strain on the Achilles tendon. Keeping the rest of the musculoskeletal system, as well as the cardiovascular system, fit while recovering from injury is of primary importance to competitive athletes.

The reason most athletes struggle with tendon healing is the desire to return to play before the tendon is ready. As discussed  here, its tempting for them to mask the pain of tendinopathy with the use of NSAIDs in order to return to play faster. Other strategies they may attempt in order to return to sport include platelet therapy. As Andy Hamilton discusses here, the evidence doesn’t support the use of platelet rich plasma (PRP) as a therapeutic modality for tendon healing. For now, the tincture of time, combined with progressive load management, is the best medicine.

References:

  1. BJSM. 2011 Oct;45:1026-28
  2. Foot Ankle Int. 2018 May 1 [Epub ahead of print]
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