Tendonitis is inflammation or irritation of a tendon, while tenosynovitis is inflammation of the synovial sheath that surrounds certain tendons. Both cause pain, stiffness, and reduced movement at the affected joint, but they involve different structures and sometimes require different treatment approaches. Together, they account for a significant proportion of musculoskeletal complaints seen in primary care.
The terms get used interchangeably in everyday conversation. Clinically, the distinction matters. Not every tendon has a synovial sheath. The Achilles, patellar, and rotator cuff tendons don’t. They can develop tendonitis but not tenosynovitis. Tendons that pass through narrow tunnels, particularly in the wrists, hands, ankles, and feet, are surrounded by sheaths and are vulnerable to both conditions.
What’s the difference between a tendon and its sheath?
A tendon is a dense cord of collagen fibres connecting muscle to bone. It transmits the force that muscles generate to move joints. Certain tendons, especially those that change direction around bony prominences, are encased in a synovial sheath. This sheath is a double-layered sleeve filled with synovial fluid that allows the tendon to glide smoothly through tight anatomical spaces.
Tendonitis involves damage to the collagen fibres within the tendon itself. The current clinical preference is to use the term “tendinopathy” because most chronic presentations show degeneration (failed healing) rather than active inflammation. A landmark histological study by Khan et al. (Sports Medicine, 1999) found that surgical specimens from chronic tendon pain showed an absence of inflammatory cells in the majority of cases.
Tenosynovitis affects the sheath rather than the tendon. The sheath swells, produces excess fluid, and restricts tendon gliding. It can result from overuse, infection, or inflammatory conditions such as rheumatoid arthritis. The distinction guides treatment: tendinopathy needs progressive loading to remodel collagen, while tenosynovitis may respond to anti-inflammatory measures and immobilisation.
Where do these conditions occur?
Tendonitis can affect any tendon in the body, but common locations include the Achilles tendon (ankle), the rotator cuff (shoulder), the patellar tendon (knee), and the lateral epicondyle tendons (elbow, as in tennis elbow). Tenosynovitis most commonly affects the wrist and hand (De Quervain’s tenosynovitis is a classic example), the ankle (tibialis posterior or peroneal tenosynovitis), and the flexor tendons of the fingers (trigger finger).
Athletes, manual workers, and musicians are disproportionately affected. On the Costa del Sol, Sarah Monaghan at Costa Health frequently treats tendon problems in golfers, padel players, and tennis enthusiasts, sports that place sustained repetitive demands on specific tendon groups.
What causes tendon problems?
Repetitive overload is the primary driver. Tendons adapt to load, but they adapt slowly, much more slowly than muscles. A study published in the Journal of Applied Physiology (Magnusson et al., 2010) demonstrated that collagen synthesis in tendons peaks 24-72 hours after loading but doesn’t fully mature for weeks. When the interval between loading bouts is too short, microdamage accumulates.
Age compounds the problem. Tendon blood supply decreases from the third decade onwards, slowing repair capacity. Hormonal factors play a role, with postmenopausal women showing higher rates of tendinopathy, likely related to oestrogen’s influence on collagen metabolism.
Certain medications increase risk. Fluoroquinolone antibiotics (ciprofloxacin, levofloxacin) carry a well-documented association with tendon damage and rupture. Statins have been linked to tendinopathy in observational studies, though the evidence is less definitive. Aromatase inhibitors used in breast cancer treatment are associated with tenosynovitis of the hands and wrists.
A specific clinical example that illustrates how quickly things can develop: a 52-year-old patient who’d been playing padel twice weekly for years suddenly developed bilateral wrist tenosynovitis after switching to a heavier racquet and playing four times a week during a tournament fortnight. The tendons were conditioned for one load level and were suddenly asked to handle double.
How are they diagnosed?
Clinical examination is the starting point. Tenderness along the tendon, pain on resisted contraction of the associated muscle, and pain on passive stretching all point towards tendon involvement. Crepitus, a grating or crackling sensation felt when the tendon moves under the examiner’s fingers, is more suggestive of tenosynovitis than tendonitis.
Ultrasound imaging is the investigation of choice for both conditions. It can visualise tendon thickening, intratendinous tears, sheath fluid, and neovascularisation (new blood vessel growth associated with chronic tendinopathy) in real time. MRI offers superior soft tissue contrast but is typically reserved for complex or surgical planning cases.
An important edge case: acute onset tenosynovitis with redness, warmth, and pain on passive finger extension in a single digit should raise immediate concern for infective (septic) tenosynovitis. This is a surgical emergency requiring urgent referral. Kanavel’s signs (fusiform swelling, flexed posture, tenderness along the sheath, and pain on passive extension) are the classic clinical markers.
How does Costa Health treat these conditions?
Tendon conditions respond best to a multidisciplinary approach that addresses the local pathology and the biomechanical factors driving it. Costa Health’s team uses chiropractic, physiotherapy, osteopathy, and sports massage depending on the location and nature of each patient’s problem.
Physiotherapy is central to tendinopathy rehabilitation. Progressive tendon loading, typically starting with isometric exercises and advancing through eccentric and heavy slow resistance protocols, stimulates collagen remodelling and restores tensile strength. The evidence supporting this approach is substantial, with Silbernagel et al. (American Journal of Sports Medicine, 2007) showing that combined eccentric and concentric loading produced superior outcomes to eccentric loading alone in Achilles tendinopathy.
For tenosynovitis, physiotherapy initially focuses on reducing sheath irritation through splinting, activity modification, and gentle range-of-motion exercises. Once the acute phase settles, graded tendon-gliding exercises are introduced to restore smooth movement within the sheath.
Chiropractic assessment addresses joint restrictions that alter tendon loading. A stiff ankle affects Achilles tendon mechanics. A restricted wrist alters extensor tendon loading. Mobilisation of the relevant joints restores normal movement patterns and reduces compensatory strain on tendons. Assessment often extends beyond the symptomatic joint, because restrictions in the spine or adjacent joints frequently contribute to altered loading at the painful site.
Osteopathic treatment examines fascial continuity and visceral influences on musculoskeletal function. Fascial restrictions proximal to the affected tendon can increase resting tension and impede healing. Osteopathic practitioners at Costa Health use soft tissue and myofascial techniques to address these broader patterns.
Sports massage directly targets the muscle-tendon unit and surrounding soft tissues. Reducing muscle tone and releasing adhesions in the muscle belly decreases resting tension on the tendon, creating a better environment for healing. Cross-fibre friction applied carefully to the affected tendon can stimulate a healing response, though this technique requires clinical judgement about timing and intensity.
What should prompt urgent medical attention?
Most tendon problems are painful but not dangerous. Seek prompt assessment if you experience a sudden snap or pop followed by immediate weakness (possible tendon rupture), rapidly spreading redness and warmth along a tendon in the hand or foot (possible infection), or bilateral tendon pain that’s developed without a clear mechanical cause (which may warrant investigation for systemic inflammatory conditions such as rheumatoid arthritis or psoriatic arthritis).
How long does recovery take?
Acute tendonitis and tenosynovitis caught within the first two to three weeks often resolve within four to six weeks with appropriate treatment. Chronic tendinopathy that’s been building for months requires a longer rehabilitation timeline, typically three to six months of structured loading. The tendon remodelling cycle is slow. Patience and consistency with prescribed exercises are the strongest predictors of a good outcome.
Costa Health’s practitioners work together across chiropractic, physiotherapy, osteopathy, and sports massage, adapting the treatment plan as the condition progresses from acute management through rehabilitation to prevention. That continuity of care, with the whole team under one roof on the Costa del Sol, makes for a smoother and more complete recovery.