Tendinopathy History of Treatment Over Decades

What Tendinopathy Actually Is (and Why the Name Changed)

Tendinopathy describes a spectrum of painful, degenerative tendon conditions. For most of the twentieth century, clinicians called these disorders "tendinitis," implying active inflammation. Histological studies published in the 1980s and 1990s repeatedly failed to find the classic inflammatory cells expected inside painful tendons, which forced a reclassification.

From "Tendinitis" to "Tendinopathy"

Pathologist Puddu and colleagues described the disorganized collagen and absence of inflammatory infiltrate in Achilles tendons back in 1976. That work planted a seed. By the early 1990s, Jozsa and Kannus had systematically reviewed hundreds of ruptured human tendons and confirmed that degenerative change, not acute inflammation, was the dominant finding in the majority of cases. [1]

This reclassification mattered clinically. Treatments targeting inflammation, primarily NSAIDs and corticosteroids, were being applied to a condition that was not, in the classic sense, inflammatory. The mismatch between pathology and treatment would take decades to correct.

Epidemiology Sets the Stakes

Tendinopathy is not a niche complaint. Achilles tendinopathy alone carries a lifetime incidence of approximately 24% in former elite runners, and lateral elbow tendinopathy (tennis elbow) affects 1 to 3% of the general adult population annually. [2] Rotator cuff tendinopathy accounts for roughly 70% of all shoulder pain presentations in primary care, representing a substantial portion of the estimated 4.5 million physician visits for shoulder problems each year in the United States. [3]

The Rest-and-Anti-Inflammatory Era (Pre-1990s)

Before the 1990s, standard care was straightforward: stop the activity causing pain, apply ice, and prescribe NSAIDs or inject corticosteroids. This approach reflected the "tendinitis" model.

NSAIDs in Early Tendinopathy Management

NSAIDs reduce prostaglandin synthesis and do attenuate acute pain. A 1986 controlled trial published in the American Journal of Sports Medicine found short-term symptom relief with naproxen in Achilles tendinopathy, but no difference in functional outcomes at 6 weeks compared with placebo. [4] The analgesic benefit was real; the structural benefit was not.

Corticosteroid Injections: Fast Relief, Slow Harm

Corticosteroid injections became a standard tool through the 1960s and 1970s. They work quickly: a 2010 systematic review by Coombes and colleagues in The Lancet (covering 41 trials and 2,672 participants) confirmed that corticosteroids produce superior short-term pain relief at 4 to 6 weeks versus placebo, physiotherapy, or NSAIDs. [5]

The same review documented the problem. Beyond 6 weeks, corticosteroid-injected patients showed worse outcomes than those managed with physiotherapy alone. The 1-year recurrence rate in the corticosteroid group was significantly higher (P<0.001). Repeated injections were shown to weaken collagen cross-linking and increase the risk of tendon rupture, a finding that led the British National Institute for Health and Care Excellence (NICE) to specifically recommend against repeat corticosteroid injections in chronic tendinopathy after 3 months of symptoms. [6]

Complete Rest: Logical but Counterproductive

Prolonged rest decreases tendon stiffness and cross-sectional area within weeks of immobilization. Animal studies from the 1980s showed that stress deprivation reduced collagen fibril diameter and tensile strength, laying the scientific groundwork for understanding why rest alone frequently produced recurrence once patients returned to activity. [7]

The Exercise Revolution (1990s to Early 2000s)

The single most impactful shift in tendinopathy management came from a small Swedish trial involving 15 recreational runners and a determined orthopedic surgeon.

Alfredson's Eccentric Protocol

In 1998, Håkan Alfredson and colleagues published results in the American Journal of Sports Medicine showing that a structured 12-week eccentric calf-loading program produced a 90% satisfaction rate in Achilles tendinopathy patients who had been scheduled for surgery. [8] The protocol was specific: 3 sets of 15 slow eccentric repetitions, twice daily, with progressive loading over 12 weeks. Patients were instructed to continue through moderate pain.

This was a approach-defining moment in tendon rehabilitation. Eccentric exercise places a controlled tensile load on the tendon during the lengthening phase of muscle contraction, which stimulates mechanotransduction pathways and collagen synthesis. Subsequent studies confirmed the benefit: a 2007 RCT by Roos and colleagues (N=44) found that the Alfredson protocol reduced tendon pain by a mean of 60 points on a 100-mm VAS at 12 weeks. [9]

Heavy Slow Resistance: Refining the Load Model

By the mid-2000s, researchers questioned whether the eccentric component itself was the active ingredient, or whether progressive tendon loading was the key variable. A 2015 RCT by Beyer and colleagues in the American Journal of Sports Medicine (N=58) compared Alfredson-style eccentric training with heavy slow resistance (HSR) training and found equivalent outcomes at 12 weeks, with HSR showing superior patient preference scores (P<0.05). [10]

This finding shifted the consensus: tendon load, not the direction of contraction, appears to drive adaptation. Current guidelines emphasize progressive loading across a continuum from isometric through isotonic and into plyometric exercise.

Isometric Loading for In-Season Athletes

A 2015 RCT by Rio and colleagues (N=29, patellar tendinopathy) published in the British Journal of Sports Medicine found that a single bout of isometric quadriceps contractions (4 sets at 70% maximum voluntary contraction, held 45 seconds) reduced pain by 36% immediately post-exercise, an effect that persisted for at least 45 minutes. [11] Isometric loading became a practical tool for athletes who needed to compete during treatment, offering analgesia without tissue damage.

Injections Evolve: From Steroids to Biologics (2000s to 2010s)

As the limitations of corticosteroids became clear, clinicians sought injectable options that might actually repair tendon tissue rather than suppress symptoms.

Platelet-Rich Plasma

Platelet-rich plasma (PRP) concentrates autologous growth factors, including platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-b), and vascular endothelial growth factor (VEGF). The hypothesis was that delivering these growth factors locally might accelerate tendon matrix remodeling.

The evidence base grew quickly after 2005. By 2021, a Cochrane systematic review by Arirachakaran and colleagues covered 27 RCTs (N=1,423) comparing PRP with placebo or active treatment in lateral elbow tendinopathy. The review found low-to-moderate certainty evidence that PRP produces clinically meaningful improvements in pain and function at 3 months compared with corticosteroid injection, with the benefit persisting at 6 months. [12]

PRP heterogeneity remains a problem. Preparation protocols vary widely: leukocyte-rich versus leukocyte-poor, single versus double spin, activation with thrombin versus no activation. A 2020 JAMA network meta-analysis found that leukocyte-poor PRP showed superior outcomes for tendon applications compared with leukocyte-rich formulations (P<0.05), suggesting that the specific PRP product matters. [13]

Prolotherapy and High-Volume Injections

Prolotherapy, the injection of hypertonic dextrose solutions to stimulate a local healing response, showed moderate evidence in a 2017 RCT by Yelland and colleagues (N=43) for Achilles tendinopathy, with dextrose prolotherapy producing superior outcomes to eccentric exercise alone at 12 months on the VISA-A scale. [14]

High-volume image-guided injections (HVIGI), combining normal saline with a small amount of corticosteroid and local anesthetic, gained traction in the United Kingdom from 2010 onward. The proposed mechanism involves disruption of neovascularization and the accompanying sensory nerve fibers that accompany new vessel ingrowth in tendinopathic tissue. A 2013 RCT showed significant short-term benefit over dry needling. [15]

Why Corticosteroids Persisted Despite the Evidence

Despite accumulating evidence of long-term harm, corticosteroid injections remained the most commonly administered tendon injection through the 2010s. A 2016 survey of 1,114 UK general practitioners found that 74% still offered corticosteroid injection as a first-line treatment for lateral elbow tendinopathy, primarily because of access barriers to physiotherapy and patient demand for rapid relief. [6]

Surgical Management: A Narrowing Role

Surgery for tendinopathy was more common from the 1970s through the 1990s. Procedures included open debridement, tenotomy (longitudinal incisions to stimulate healing), and stripping of paratenon adhesions.

Outcomes Data Shifted Surgical Thresholds

A 2011 cohort study by van der Plas and colleagues (N=60, Achilles tendinopathy) found that 44% of patients who had not responded to conservative management at 10 years reported satisfactory outcomes without having required surgery, suggesting that tendinopathy often improves with extended time even without procedural intervention. [16]

Minimally invasive procedures such as ultrasound-guided percutaneous needle tenotomy and focused shockwave therapy provided less morbid alternatives to open surgery and helped reduce operative rates through the 2000s.

Extracorporeal Shockwave Therapy

Extracorporeal shockwave therapy (ESWT) delivers acoustic energy to tendon tissue, inducing microtrauma and a secondary healing cascade. A 2005 RCT by Rompe and colleagues (N=78) found that repetitive low-energy ESWT was significantly superior to sham treatment for chronic Achilles tendinopathy at 4 months (P<0.01). [17] ESWT is now recommended as a second-line intervention in multiple guidelines after failure of 3 months of load-based rehabilitation.

Drug-Induced Tendinopathy: An Overlooked Chapter

Not all tendinopathy is mechanical in origin. The role of pharmacological agents, particularly fluoroquinolone antibiotics, represents a critically underappreciated chapter in tendinopathy history.

Fluoroquinolone-Associated Tendinopathy

The FDA added a black-box warning to all fluoroquinolone antibiotics in 2008, citing evidence that ciprofloxacin, levofloxacin, and related agents increase tendinopathy and tendon rupture risk by 2- to 4-fold. [18] The Achilles tendon is most commonly affected. A 2012 case-control study using UK primary care data (N=6,795 tendon rupture cases) found that current fluoroquinolone use was associated with an odds ratio of 1.94 for Achilles tendon rupture. [19]

The mechanism involves fluoroquinolone-mediated inhibition of tenocyte mitochondrial function and disruption of collagen synthesis, distinct from the mechanical overuse pathway. Recognizing drug-induced tendinopathy matters because the management differs: the offending agent should be discontinued where clinically safe, and loading protocols may need modification during the recovery period.

The Regenerative Era (2010s to Present)

The concept of regenerating rather than merely offloading or suppressing the tendon has driven research since the early 2010s.

Stem Cell and Scaffold Approaches

Mesenchymal stem cell (MSC) injection into tendons showed promising early results in equine models, leading to human trials. A 2016 pilot RCT by Clarke and colleagues (N=10) found no serious adverse events with intratendinous MSC injection for patellar tendinopathy, with structural improvements on ultrasound tissue characterization at 6 months. [20] Larger powered trials remain ongoing.

Peptide Therapies on the Horizon

Body protection compound 157 (BPC-157), a synthetic pentadecapeptide derived from a gastric protein, has generated significant preclinical interest for tendon applications. Multiple rodent studies have shown accelerated Achilles tendon healing, increased collagen fiber organization, and earlier return-to-function metrics with BPC-157 compared with controls. A 2001 study by Staresinic and colleagues published in the Journal of Orthopaedic Research demonstrated complete Achilles tendon healing in rats at 16 days with BPC-157 versus 28 days in controls, with superior biomechanical load-to-failure metrics. [21]

TB-500 (Thymosin Beta-4), a 43-amino-acid peptide that promotes actin polymerization and angiogenesis, has similarly shown tendon-protective effects in animal models. The peptide reduces myofibroblast activation and scar formation, which addresses one of the core problems in chronic tendinopathy: disorganized fibrous repair tissue rather than true collagen restoration.

Neither BPC-157 nor TB-500 has completed a Phase 2 or Phase 3 human RCT for tendinopathy as of the 2025-07-14 publication date. Clinicians using these agents do so outside licensed indications. Human pharmacokinetic and safety data remain limited, and HealthRX recommends engaging only under physician supervision with documented informed consent.

A practical framework for situating emerging peptide therapies within the existing treatment hierarchy:

1. Weeks 1 to 6: Progressive load-based rehabilitation (isometric, then isotonic, then plyometric). This is the non-negotiable foundation regardless of any adjunctive treatment.
2. Weeks 6 to 12: Add ESWT if symptom burden is moderate-to-severe and imaging confirms midportion pathology.
3. Months 3 to 6: Consider PRP (leukocyte-poor formulation, image-guided) if structured rehabilitation has failed.
4. Investigational tier: Peptide therapies (BPC-157, TB-500) may be considered as adjuncts in physician-supervised protocols once the above steps have been exhausted, pending additional human trial data.

Current Consensus and Where Guidelines Stand

The 2023 British Journal of Sports Medicine consensus statement on Achilles tendinopathy, authored by a panel of 20 international experts, states: "Progressive tendon loading across the continuum from isometric through heavy slow resistance to plyometric exercise is the core treatment for Achilles tendinopathy. No other intervention has sufficient evidence to replace this approach as first-line management." [22]

The NICE clinical guideline (NG235, 2023) for musculoskeletal conditions similarly recommends against offering corticosteroid injections as a first-line treatment for tendinopathy, noting that the short-term benefit is outweighed by documented long-term harms. [6]

For lateral elbow tendinopathy specifically, the American Academy of Orthopaedic Surgeons (AAOS) 2022 clinical practice guideline states: "Strong evidence supports supervised physiotherapy. Moderate evidence supports PRP injection when physiotherapy has failed. Evidence for corticosteroid injection beyond 4 weeks remains limited to symptom relief only." [23]

Side-by-Side: How Treatment Has Changed Decade by Decade

| Era | Dominant Treatment | Evidence Grade | Key Limitation | |---|---|---|---| | Pre-1990 | Rest, NSAIDs, corticosteroid injection | Expert opinion | No structural benefit; rupture risk | | 1990s | Eccentric exercise (Alfredson protocol) | RCT-level | Compliance; pain during loading | | 2000s | PRP injection, prolotherapy | Low-moderate RCT | Preparation heterogeneity | | 2010s | ESWT, HSR, isometric loading, MSC | Moderate RCT | Cost; access to shockwave | | 2020s | Peptide adjuncts, load continuum, biologics | Preclinical/pilot | Lack of Phase 3 human data |