Tendinopathies & Bursitis (Knee Overview)

A round-up of knee-region tendinopathies and bursitides not covered by their own dedicated page. See also knee pain (approach).

Patellar tendinopathy (“jumper’s knee”)

Patellar tendinopathy is an overuse injury of the knee extensor mechanism caused by repetitive mechanical stress during athletic activities that involve jumping, landing, acceleration, deceleration, and cutting, most often at the inferior pole of the patella where the tendon inserts. Contrary to traditional belief, patellar tendinopathy does not involve inflammation of the knee extensor tendons — studies dating back 40 years describe it as a degenerative condition, and classic inflammatory cells are typically absent on histology, which is why many clinicians consider “tendinitis” a misnomer and prefer tendinosis.

• Demographics: athletes in jumping sports (basketball, netball, high jump). Approximately 45% of elite jumping athletes and up to 14% of recreational jumping athletes have patellar tendinopathy symptoms at some point in their career.
• History: gradual-onset pain at the inferior pole of the patella, worse with activity (especially jumping), improved with rest.
• Examination: localised tenderness at the inferior patella — best assessed with the leg extended: press down on the superior patella to tilt the inferior pole up, then palpate underneath it. Usually sharp pain.
• Investigations: primarily a clinical diagnosis. Increased patellar tendon thickness of 8mm on ultrasound in the preseason has been shown to be highly predictive of symptomatic patellar tendinopathy during the season. Plain radiographs (AP, lateral, skyline) are recommended to exclude any acute bony injuries or pathologies.
• Staging: Blazina et al first described patellar tendinopathy in 1973 and proposed a staging system based on the timing of pain relative to physical activity, still widely used: stage 1, pain only after activity; stage 2, pain at the start of activity, easing with warm-up then recurring with fatigue; stage 3, pain during activity and at rest with declining performance; stage 4, complete tendon rupture.
• Management: rest from the offending activity then graded return; physiotherapy for strengthening; adequate warm-up/cool-down. Relative rest is preferred over complete immobilisation to minimise tendon and muscle atrophy. Eccentric training has been shown to be noninferior to open patellar tenotomy at 12 months, so it is recommended that eccentric training be tried for 12 weeks before offering surgical treatment. The use of NSAIDs and corticosteroid injections should be discouraged, as patellar tendinopathy is primarily a degenerative condition and these interventions provide only short-term relief without addressing the underlying tendon pathology. Surgical treatment is typically recommended only after 6 months of nonsurgical methods have failed, as these methods are up to 90% effective.

Mild-to-moderate pain may persist for up to 15 years in adult athletes with patellar tendinopathy, but it does not appear to limit leisure-time physical activity.

Pes anserine (anserinus) tendinopathy/bursitis

The pes anserinus (“goose’s foot”) refers to the conjoined tendons of the sartorius, gracilis, and semitendinosus as they insert on the anteromedial proximal tibia, with a bursa lying beneath. Medial side of the knee; common in overweight, middle-aged/elderly women. Pes anserinus bursitis is characterised by pain at the pes anserine insertion, typically triggered by activities such as stair climbing or rising from a seated position, and pain is also aggravated by resisted knee flexion. Factors like obesity and valgus knee deformity, especially in middle-aged women, further elevate the risk, and tight hamstrings exert excessive pressure on the bursa, causing mechanical and friction-based irritation. The condition is also closely associated with knee osteoarthritis.

Examination: tenderness is characteristically elicited over the proximal medial tibia, approximately 5 to 7cm below the anteromedial joint margin — the conjoined tendons’ insertion point.

Management: most cases are self-limiting and respond to rest, ice, NSAIDs and physical therapy, which focuses on stretching and strengthening key muscle groups, including the adductors, abductors, quadriceps, and hamstrings. Corticosteroid injection (with or without local anaesthetic) is reserved for persistent cases; platelet-rich plasma injection has also been used, but injections should be limited to no more than 3 yearly. Pes anserine bursitis is generally self-limiting, mostly resolving with nonoperative management.

Biceps femoris tendinopathy/bursitis

Common in sprinters. No dedicated current guideline was found specifically on biceps femoris (hamstring) tendinopathy for this page — manage per the general tendinopathy principles below, and consider onward referral if it fails to settle with rest and physiotherapy.

Iliotibial band (ITB) syndrome

Common in distance runners, increasing incidence with age. Gradual-onset, well-localised pain 1–2 cm above the lateral joint line, from friction of the ITB over the lateral femoral condyle. Physiotherapy and activity modification are first-line, and most patients improve within 4-8 weeks of non-operative treatment.

Surgery is reserved for cases refractory to at least 6 months of non-operative management. Multiple surgical techniques (ITB release, lengthening, bursectomy) have demonstrated success in that refractory group, including one arthroscopic technique with a 97% good-to-excellent result — not the routine scarring/tightness once assumed.

Pre-patellar bursitis

The prepatellar bursa lies between the patella and the overlying subcutaneous tissue, and represents the most commonly affected bursa of the knee — the second most commonly affected bursa overall, after the olecranon bursa. Inflammation of the bursa overlying the patella from repetitive low-grade trauma (kneeling occupations — cleaners, carpet layers). Prepatellar bursitis can also arise from gout, rheumatoid arthritis, or infection, and immunosuppression (diabetes mellitus, chronic steroid use, haemodialysis) increases the risk of developing bursitis. It is estimated to have an annual incidence of about 1 in 10,000 individuals, with more than 80% of patients being men aged 40–60 years; up to one-third of cases presenting for care are septic.

• History: swelling and pain over the pre-patellar bursa.
• Examination: reduced knee extension; acutely red, swollen and painful if infected. A skin-temperature difference of around 2.2°C between the affected bursa and the unaffected contralateral bursa is a sensitive and specific sign of septic bursitis.
• Investigations: if infection is a concern — aspirate for culture ± microscopy for crystal arthropathy. Bursal fluid leukocytosis above 2000/mm³ has a sensitivity of 94% and specificity of 79% for septic bursitis, and culture of the aspirate is the gold standard for diagnosis.
• Management: rest, NSAIDs, ± corticosteroid injection (if no infection); antibiotics if infected bursitis is suspected. Oral and intrabursal antimicrobial therapy alone is unlikely to be beneficial for septic bursitis — hospitalisation, needle aspiration and intravenous antibiotics are indicated instead. Incision and drainage is rarely needed but sclerotherapy may help recalcitrant non-septic cases.
• Complications: mostly secondary to management — infection introduced at aspiration, a fistula between the skin surface and the bursa, and subcutaneous atrophy or (rarely) patellar tendon rupture from corticosteroid injection. See Extensor Mechanism Ruptures for recognition and management of a complete tear.
• Referral: treatment-resistant cases may need an orthopaedic surgery consultation to arrange definitive surgical management.

Infrapatellar fat pad inflammation (Hoffa syndrome)

The fat pad extends across the lower patella, deep to the patellar tendon. This structure — also called Hoffa’s fat pad or the infrapatellar fat pad (IFP) — is a potent source of pain due to its robust innervation by nociceptive free nerve endings and fibres targeted by substance P, and impingement is well documented as a source of anterior knee pain in runners, cyclists, and soldiers. Compression injury (jumping or similar trauma) causes sharp pain on kneeling. Patients describe a burning or aching sensation to the anterior knee, localised deep to and on either side of the patellar tendon adjacent to the inferior pole of the patella, usually worse with full knee extension or prolonged flexion. The Hoffa test — firm thumb pressure just under the patella, beside the patellar tendon, with the knee then extended from 30° of flexion — reproduces the pain and supports the clinical diagnosis.

Evaluation: sagittal MRI is the gold-standard imaging modality for assessing fat pad pathology, though clinical assessment matters more than imaging alone, since fat-pad oedema can also be seen on MRI in people without symptoms.

Management: physical therapy — vastus medialis strengthening and taping to offload the patellar tendon and fat pad — is the mainstay of treatment. Corticosteroid injection has also been used and has demonstrated satisfactory results in refractory cases; arthroscopic resection is reserved for those who don’t settle with conservative management. Most cases are successfully treated conservatively, and the vast majority of those who do need arthroscopic debridement return to their pre-injury level of sporting activity.

General tendinopathy treatment principles

Rest from the offending activity; physiotherapy to correct underlying biomechanics; ± steroid/anaesthetic injection.