2.8 Overuse Tendinopathies & Regenerative Medicine

Overuse Tendinopathies & Regenerative Medicine

Tendinopathy is a Domain D staple and a "treatments" topic under Domain A (modalities, regenerative medicine). The shift from inflammatory "tendinitis" to degenerative "tendinosis" frames modern management around load management and collagen remodeling rather than anti-inflammatory suppression alone.

Tendinosis Pathophysiology

Repeated Microtrauma  ──►  Failed Healing Response  ──►  Collagen Disorganization
       │                                                  + Neovascularization
       │                                                  + Tenocyte Apoptosis
       └──── Tendinosis (Degenerative, Minimal Inflammation)

Chronic overuse tendons show collagen fibril disorganization, neovascularization (often painful, with ingrowth of nociceptors alongside vessels), increased glycosaminoglycans, and tenocyte apoptosis—not the robust inflammatory infiltrate implied by "tendinitis." This explains why anti-inflammatory monotherapy underperforms and why loading therapy succeeds.

High-Yield Tendinopathies

Eccentric Loading & the Alfredson Protocol

Eccentric exercise—lengthening contraction under load—is the most evidence-supported intervention. The Alfredson Achilles protocol uses two exercises (knee straight and bent) performed as 3x15 twice daily for 12 weeks, progressing load despite mild pain (acceptable up to ~3-5/10). For patellar tendinopathy, single-leg decline-board eccentric squats are effective. Load progression, not rest, drives collagen remodeling.

Injection Therapies

• Corticosteroid: useful short-term (a few weeks) for lateral epicondylitis and rotator cuff; risks include tendon weakening, skin atrophy, and depigmentation. Avoid repeated injections (>3).
• Dry needling: disrupts degenerative tissue and may stimulate healing; often combined with PRP or autologous blood.
• Autologous blood / prolotherapy: limited evidence; may stimulate inflammatory healing.

Regenerative Biologics

Platelet-rich plasma (PRP) concentrates platelet growth factors (PDGF, TGF-beta, VEGF) to stimulate tendon healing. Evidence is most supportive for lateral epicondylitis and patellar tendinopathy; results for Achilles and rotator cuff are mixed. Leukocyte-rich vs leukocyte-poor preparations differ by tissue. Autologous tenocyte and mesenchymal stem cell preparations remain investigational for most indications. Candidates should know the moderate, condition-specific evidence and the absence of long-term superiority over exercise for many tendons—not uncritical adoption.

Rehab Principles Summary

1. Relative rest and activity modification (avoid provocative load; not absolute rest).
2. Progressive eccentric loading—the rehabilitative cornerstone.
3. Address contributing biomechanics (e.g., scapular dyskinesis, foot overpronation).
4. Reserve injections for refractory cases or to facilitate loading; combine with rehab, never substitute.
5. Surgery only after failed comprehensive conservative program (typically 6-12 months).

Tendon Anatomy & Healing

Tendons transmit muscle force to bone and are relatively avascular, especially at "watershed zones" (e.g., supraspinatus mid-substance, Achilles 2-6 cm above insertion) where degeneration and rupture cluster. Healing proceeds through inflammatory, proliferative, and remodeling phases, but tendons heal slowly with disorganized collagen and modest strength. This biology underlies the weeks-to-months loading requirement and the recurrence risk when load is progressed too quickly.

Common Tendon Ruptures

Acute ruptures require surgical consideration for active patients and younger individuals; chronic degenerative tears are usually managed conservatively first. The Thompson test (calf squeeze with no plantarflexion) diagnoses Achilles rupture; the hook test diagnoses distal biceps rupture.

Load Management & Biomechanics

Addressing contributing biomechanics prevents recurrence: scapular dyskinesis for rotator cuff, gluteus medius weakness for iliotibial band and patellar issues, foot overpronation for Achilles/tibialis posterior, and grip/racquet technique for epicondylitis. Taping and orthoses may offload symptomatic tendons during loading. Load progression follows the "acute:chronic workload" principle—increasing total load modestly each week to avoid spikes that provoke symptoms.

When to Refer for Surgery

Surgical referral is reasonable when (1) comprehensive conservative management (eccentric loading ± injection) fails over 6-12 months, (2) a large acute tear in a young/active patient, or (3) functional demands are not met. Tendon transfer or debridement options exist; the physiatrist coordinates prehab (maximize strength and ROM before surgery) and post-surgical rehabilitation. The goal is to exhaust the evidence-based conservative pathway before surgical intervention, since results of surgery for degenerative tendons are often comparable to continued exercise.