Patellar Tendinitis

Pain at the patellar tendon, usually at its proximal attachment to the inferior pole of the patella, from repetitive loading, known as jumper's knee. The process is tendinopathy with focal collagen degeneration, increased neovascularity and little inflammatory cell infiltrate, not a primary inflammatory condition. Early peritendinitis with oedema is the source of the acute "tendinitis" picture.

• Prevalence is 14 to 45% in elite jumping athletes (volleyball, basketball, athletics, football), and about 8% in recreational athletes. It affects mostly men aged 15 to 30.
• Causes and risk factors: high volume of jumping and landing, hard surfaces, rapid increase in training, quadriceps tightness, hamstring tightness, reduced ankle dorsiflexion, leg length difference, patella alta, high body mass index, and use of fluoroquinolones or systemic corticosteroids.
• Stages: pain after activity only, pain at the start and end of activity, pain during activity affecting performance, and prolonged pain with daily activity or partial or complete rupture.
• Recovery is slow, and about 30 to 50% of athletes continue to have symptoms at 6 years if poorly managed.

• Localised anterior knee pain at the inferior pole of the patella, worse on jumping, landing, running, squatting, climbing stairs and prolonged sitting, and with the first steps after rest. Pain is reproduced by single leg decline squat, and by palpation of the tendon with the knee extended (the tender area moves with a flexed knee).
• There may be local thickening and warmth, tight quadriceps and hamstrings, and no effusion, joint line tenderness or ligament laxity.
• Differential diagnosis: patellofemoral pain syndrome, quadriceps tendinopathy, fat pad impingement, Osgood-Schlatter disease (adolescents, at the tibial tubercle), Sinding-Larsen-Johansson disease (adolescents, at the inferior pole), prepatellar and infrapatellar bursitis, patellar stress fracture, patellar tendon partial tear or rupture, meniscal tear, plica syndrome and referred hip pain.
• Red flags: sudden pain with a pop and inability to extend the knee (rupture, with a high riding patella), a hot swollen joint, locking, night pain, weight loss and a history of cancer.
• Complications: chronic pain, partial tear or rupture (especially after steroid injection), muscle wasting, and loss of sport.

• Clinical. Assess jump and landing technique, load history, flexibility, and the strength of the quadriceps and hip stabilisers.
• Ultrasound shows tendon thickening, hypoechoic areas, neovascularity, partial tears, and calcification. MRI shows intratendinous signal change and tears, and excludes other lesions, and is used when the diagnosis is unclear.
• X-ray if bone pathology (stress fracture, avulsion, patella alta, tumour) is suspected.

• Load management: reduce but do not stop jumping and loading. Keep pain at 4 out of 10 or less during activity, with settling within 24 hours. Substitute cycling or swimming for fitness. Complete rest weakens the tendon.
• Analgesia: paracetamol 1 g orally 6 hourly, topical diclofenac 1% gel 2 to 4 g 3 to 4 times daily, and a short course of ibuprofen 400 mg 8 hourly with food for 5 to 7 days for the acute phase. Ice for 10 to 15 minutes after activity.
• Exercise therapy, first line, 12 weeks or more:
  • Isometric holds for pain relief: 5 repetitions of 45 seconds at about 70% maximal effort (knee at 60 degrees of flexion), once or twice daily, with relief for up to 45 minutes.
  • Eccentric decline squats: 3 sets of 15 on a 25 degree decline board, twice daily for 12 weeks, with added load as pain allows.
  • Heavy slow resistance (leg press, squat and hack squat, 3 to 4 sets of 6 to 15 repetitions, 3 times weekly) with equal results to eccentric work and better compliance.
  • Then plyometrics, energy storage loading, and sport specific training.
  • Address hip and trunk strength, quadriceps and hamstring flexibility, and landing mechanics.
• Adjuncts with limited or mixed evidence: patellar strap or brace (reduces pain during sport), extracorporeal shock wave therapy (3 to 5 weekly sessions), glyceryl trinitrate patch (a quarter of a 5 mg per 24 hour patch, applied over the tender area and changed daily for 12 weeks, with headache as the main side effect), platelet rich plasma (3 to 5 mL ultrasound guided, with uncertain benefit), high volume image guided injection, and sclerosing injection of neovessels (polidocanol).
• Do not inject corticosteroid into or around the tendon, because of the risk of rupture and degeneration.
• Stop or substitute fluoroquinolones, and review statin and steroid exposure.
• Surgery after at least 6 months of correct conservative treatment: arthroscopic or open debridement of the diseased tendon with or without drilling of the inferior pole, with good results in about 70 to 85% and a return to sport in 4 to 6 months.
• Tendon rupture: urgent orthopaedic repair.
• Prevention: gradual increases in training load (up to about 10% per week), warm up, hip and quadriceps strengthening, and suitable shoes.
• Special groups:
  • Adolescents: look for Osgood-Schlatter and Sinding-Larsen-Johansson disease, and manage with load modification, stretching and a strap.
  • Elderly: lower load exercise, and avoid fluoroquinolones.
  • Pregnancy: physiotherapy and paracetamol. Avoid NSAIDs after 20 weeks.
  • Diabetes and obesity: optimise glucose and weight.
  • Renal impairment and gastrointestinal disease: avoid oral NSAIDs.
• Follow up: review at 6 weeks and at 3 months. Refer to sports medicine or orthopaedics for suspected partial tear, failure at 3 to 6 months, or consideration of procedures.