# Orthopaedic Surgery/Patellar Tendinitis

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Patellar Tendinitis (Patellar Tendinopathy), also known as Jumper's Knee, is a painful condition of the knee, which primarily occurs in sports requiring strenuous of jumping (as the name implies). The condition is caused by small tears in the patellar tendon which results in localized tenderness of the patellar tendon. The tears are typically caused by accumulated stress on the patellar or quadriceps tendon.
The patellar tendon is a band of tissue that connects the patella (the kneecap; see fig 1) to the tibia (shin bone). The tendon is used when you extend your knee. When you contract your quadriceps muscles, they pull on the patellar tendon, which in turn pulls on the kneecap and extends the knee.

## Symptoms

The most common symptoms include:
* Pain and tenderness around the patellar tendon (behind lower part of the kneecap, or just below the knee; see fig 1)
* Swelling in the area below the kneecap
* Pain when jumping, running, or squatting
* Pain when bending or straightening the leg
* Crepitus (crunching or grating sound) when bending or straightening the leg
* In some cases, pain at rest
* Weakness and instability of the knee

## Differential diagnosis

* Patellofemoral Pain Syndrome (PFPS)
* Osgood-Schlatter Disease
* Chondromalacia Patellae
* Prepatellar Bursitis
* Patellar tendinitis (final diagnosis)

### 1. Patellofemoral Pain Syndrome (PFPS)

* Pain Location: Anterior knee pain, typically around the patella.
* Aggravating Activities: Pain worsens with activities that load the patellofemoral joint, such as squatting, running, climbing stairs, or sitting for long periods.
* Symptoms: Often associated with a grinding or popping sensation (crepitus) when bending the knee. Unlike patellar tendinitis, pain is more diffuse around the kneecap rather than being localized to the patellar tendon.
* Clinical Tests: Positive Clarke's test (pain with quadriceps contraction against resistance).
* Key Distinctive Factor: Diffuse pain around the patella, not localized to the patellar tendon, and often associated with crepitus.
* Imaging Studies: MRI or CT scan may show cartilage damage or malalignment of the patella.

### 2. Osgood-Schlatter Disease

* Pain Location: Pain and swelling at the tibial tuberosity, where the patellar tendon attaches.
* Population: Commonly affects adolescent athletes during growth spurts.
* Symptoms: Tenderness and pronounced bony prominence at the tibial tuberosity. Pain is specifically located below the kneecap rather than in the patellar tendon itself.
* Clinical Tests: Physical examination reveals tenderness and swelling over the tibial tuberosity, often without significant pain during quadriceps contraction.
* Key Distinctive Factor: Pain and swelling are localized at the tibial tuberosity, with a pronounced bony prominence.
* Imaging Studies: X-ray may show fragmentation or irregular ossification at the tibial tuberosity.

### 3. Chondromalacia Patellae

* Pain Location: Pain under the patella due to the softening and deterioration of the cartilage.
* Aggravating Activities: Pain worsens with activities like squatting, climbing stairs, or prolonged sitting (theater sign).
* Symptoms: Anterior knee pain with crepitus (grinding sensation) during knee movements. Unlike patellar tendinitis, pain is more diffuse and under the kneecap rather than localized to the tendon.
* Clinical Tests: Positive patellar compression test (pain with patellar compression and movement).
* Key Distinctive Factor: Diffuse pain under the patella, often accompanied by crepitus during knee movements.
* Imaging Studies: MRI can reveal cartilage damage and changes in the patellar alignment.

### 4. Prepatellar Bursitis

* Pain Location: Swelling and tenderness over the patella.
* Symptoms: Swelling, redness, and warmth over the kneecap. Pain is usually localized to the front of the knee and not directly involving the patellar tendon.
* History: Often caused by prolonged kneeling or direct trauma to the knee.
* Clinical Tests: Physical examination reveals fluid-filled swelling over the patella, with increased warmth and redness, unlike the more localized pain of patellar tendinitis.
* Key Distinctive Factor: Visible and palpable swelling over the patella with associated redness and warmth, indicating inflammation of the bursa.
* Imaging Studies: Ultrasound or MRI can confirm the presence of fluid in the bursa and inflammation.

### 5. Patellar Tendonitis (final diagnosis)

* Pain Location: Pain and tenderness localized to the patellar tendon, typically just below the kneecap.
* Aggravating Activities: Pain worsens with activities involving knee extension, such as jumping, running, or squatting.
* Symptoms: Pain and tenderness around the patellar tendon, swelling below the kneecap, pain when bending or straightening the leg, and possible crepitus during movement.
* Clinical Tests: Tenderness to palpation over the patellar tendon, pain with resisted knee extension.
* Key Distinctive Factor: Localized pain and tenderness at the patellar tendon, especially just below the kneecap, often triggered by repetitive stress or overuse.
* Imaging Studies: Ultrasound or MRI can show thickening and degeneration of the patellar tendon, confirming the diagnosis.

## Causes and risk factors

The primary cause of patellar tendinitis is activities that place repetitive stress on the patellar tendon. These are activities like jumping, plyometrics, running, walking, bicycling.
* During a 2-year study involving 138 male and female students of physical education it was found that 19 of the 138 students (approx. 14%) developed patellar tendinitis. Before the study began, flexibility, strength, among other factors were tested. The results showed that having lower flexibility of the quadriceps and hamstring muscles may contribute to the development of patellar tendinitis in athletes.
* Sport specialization has been correlated with instances of patellar tendinopathy. Hall et al. completed a retrospective cohort study of 546 middle and high school female athletes (basketball, soccer, and volleyball) and found that single sport athletes have a four time greater risk of developing patellar tendinopathy as compared to multi-sport athletes.
* Two groups of investigators have found that leg-length inequality is associated with patellar tendon pain.

## Treatment
### Exercises

* Eccentric single-leg decline squat
** Decline board should be between a 15 ° and 30 ° decline.
** Keep knee flexion less than or equal to 60 ° to avoid excessive loading of the patellofemoral joint.
*** Patellar tendon loading increases as the decline angle increases, and at angles of knee flexion higher than 60°, the patellofemoral forces rise at a higher rate than the tendon forces.
** On the 0 to 10 pain scale, the patient should be greater than 0 and less than 5. Thus, a little pain when performing the exercise is expected.
** As the exercise becomes less painful and easier for the patient to complete, increase the load:
*** The addition of the 10kg (22lb) backpack has been shown to cause even higher tendon loading.
*** Hand-held weight (i.e. dumbbells) is also an option.
** To be repeated 3-14 times per week. There is a lack of conclusive evidence on the optimal dosage for eccentric exercise specifically for patellar tendinopathy.
** Recommended prescription of 3 sets of 10 to 15 repetitions, or less based on the patient's ability and pain experienced.
* Drop squats
** Curwin and Stanish demonstrated drop squats were an effective exercise for assisting in alleviation of patellar tendon pain.
*** "Their [Curwin and Stanish’s] program involved of six weeks of training, progressing in the first week from a slow speed to faster speeds, and then adding resistance in weeks two through six. During the six-week training period, the patients were to perform three sets of 10 repetitions daily; after the sixth week the training was reduced to three times weekly. In a retrospective review of 66 patients treated with the eccentric program for patellar tendon pain, the authors reported complete relief of pain in 20 patients, marked decrease in symptoms in 42 patients, and four patients reported worsening of symptoms."

### Other treatments

TODO.

## Returning to activity
### Volleyball

TODO

### Basketball

TODO

### Running

The Run Doctor, a running injury clinic, recommends the following checklist to be completed before considering returning to running:
* Patient should be able to straighten his or her knee without pain.
* The patient's knee should not be visibly swollen.
* The patient should be able to jog in a straight line without limping.
* The patient should be able to perform 45-degree and 90-degree cuts without difficulty.
* The patient should be able to jump on both legs without pain.
* The patient should able to jump on the injured leg without pain.
Not all runners experiencing patellar tendonitis will need to take time off from activity, however they may need to reduce their training load.

## References

* 1 2 "Patellar Tendonitis in Henderson | Henderson Knee Pain | Seven Hills Knee Pain". woodworthorthopedics.com. Retrieved 2023-09-16.
* ↑ "Patellar Tendon Tear - OrthoInfo - AAOS". www.orthoinfo.org. Retrieved 2023-09-17.
* ↑ "Patellar and Quad Tendon Repair: St. Elizabeth's Medical Center | Steward Family Hospital | Brighton MA". www.semc.org. Retrieved 2023-09-17.
* ↑ "Patellar Tendonitis (Jumper's Knee)". www.hopkinsmedicine.org. 2021-04-30. Retrieved 2023-09-16.
* ↑ Witvrouw, Erik; Bellemans, Johan; Lysens, Roeland; Danneels, Lieven; Cambier, Dirk (2001–2003). "Intrinsic Risk Factors for the Development of Patellar Tendinitis in an Athletic Population: A Two-Year Prospective Study". The American Journal of Sports Medicine. 29 (2): 190–195. doi:10.1177/03635465010290021201. ISSN 0363-5465.
* ↑ Hall, Randon; Foss, Kim Barber; Hewett, Timothy E.; Myer, Gregory D. (2015-2). "Sports Specialization is Associated with An Increased Risk of Developing Anterior Knee Pain in Adolescent Female Athletes". Journal of sport rehabilitation. 24 (1): 31–35. doi:10.1123/jsr.2013-0101. ISSN 1056-6716. PMC 4247342. PMID 24622506. {{cite journal}}: Check date values in: |date= (help)
* 1 2 3 4 Reinking, Mark F. (2012–2016). "CURRENT CONCEPTS IN THE TREATMENT OF PATELLAR TENDINOPATHY". International Journal of Sports Physical Therapy. 11 (6): 854–866. ISSN 2159-2896. PMC 5095939. PMID 27904789.
* ↑ Duri, Z A; Aichroth, P M; Wilkins, R; Jones, J (1999-01-01). "Patellar tendonitis and anterior knee pain". The American journal of knee surgery. 12 (2): 99–108. ISSN 0899-7403. PMID 10323501.
* ↑ Kujala, U. M.; Osterman, K.; Kvist, M.; Aalto, T.; Friberg, O. (1986). "Factors predisposing to patellar chondropathy and patellar apicitis in athletes". International Orthopaedics. 10 (3): 195–200. doi:10.1007/BF00266208. ISSN 0341-2695. PMID 3771029.
* 1 2 3 Zwerver, J; Bredeweg, S W; Hof, A L (2004–2007). "Biomechanical analysis of the single‐leg decline squat". British Journal of Sports Medicine. 41 (4): 264–268. doi:10.1136/bjsm.2006.032482. ISSN 0306-3674. PMC 2658963. PMID 17224441.
* ↑ Curwin, Sandra. "Tendinitis : its etiology and treatment". (No Title).
* 1 2 "Patellar Tendonitis – The Run Doctor". Retrieved 2023-09-16.
* ↑ Muaidi, Qassim I. (2020). "Rehabilitation of patellar tendinopathy". Journal of Musculoskeletal & Neuronal Interactions. 20 (4): 535–540. ISSN 1108-7161. PMC 7716685. PMID 33265081.