What is Patellar Tendinopathy?
Patellar tendinopathy generally occurs when the load on the patella tendon exceeds its capacity, causing pain localized to the inferior pole of the patella. Under normal conditions, the tendon responds to load by stiffening. However, abnormalities from non-optimal loading patterns can cause disruption to the collagen fibres that make up the tendon.
What does the Patella Tendon do?
The patella tendon is a structure situated below the patella (kneecap) connecting the patella to the tibia (shinbone). Its role is to transfer forces from the quadriceps muscle to your upper shinbone through the patella.
The level of pathology has been described by Cook & Purdam (2009) and follows these proposed stages:
1. Reactive tendinopathy
With acute compressive or tensile overload, the cells undergo a non-inflammatory proliferative response causing thickening as opposed to stiffening. This generally occurs through unaccustomed physical activity.
2. Tendon disrepair
Attempted continual healing following a reactive stage but with increased breakdown of the matrix. On a cellular level, there is an increase in the separation and disorganisation of collagen.
This stage is typically from overloaded tendons.
3. Degenerative tendinopathy
In this stage, there is an even higher breakdown of matrix, such that some areas may undergo apoptosis. Pathological changes at this stage are generally irreversible.
Risk Factors of Patellar Tendinopathy:
- This condition largely affects a younger population (15-30 years old), who participate in sports which repetitively load the tendon, such as basketball, tennis, volleyball, football, or athletic jump events.
- The condition tends to affect men more than women.
- Anterior knee pain focally on the patellar tendon
- Tenderness on palpation of the patellar tendon
- Pain is aggravated by jumping, landing or running and sometimes prolonged sitting
- Tendon usually feels stiffer in the morning and has a ‘warm up’ effect
- Tendon may appear thicker, or swollen compared to the unaffected side
What does a treatment plan look like?
Malliaras et al. (2015) have proposed an evidence-based program for patellar tendon rehab, as pictured below. Generally, principles of treatment follow the following stages:
Stage 1: Isometric Loading
- Has been shown to reduce pain in the acute stages of management and throughout a treatment program when pain needs to be settled but still allowing loading of the muscle-tendon unit (Naugle et al., 2013).
Stage 2: Isotonic Loading
- Slow, heavy resistance training (concentric and eccentric) has been shown to be superior over eccentric loading for patient subjective satisfaction (Malliaras et al., 2013), however, all loading programs are beneficial for pain reduction and return to function.
- Begin with high reps and 10-60degrees of knee flexion, progressing to lower reps and full range of knee motion as pain allows (Breda et al., 2020).
Stage 3: Energy storage
- Introduction of plyometric movements and loaded activities such as running, jump squats, box jumps and lateral movements) every third day, alternating with isometric and isotonic exercises the other two days, respectively (Breda et al., 2020).
Stage 4: Progressive return to sport
- Sport-specific drills should be included and progressed gradually to meet the demands of the sport. There should be 2-3 days between training sessions to allow for adequate tendon recovery (Breda et al., 2020).
Progression through stages should be individualised, based on pain experienced a test of pain provocation, such as the single-leg squat. A score of 3 or less on the VAS scale and at least 1 week of exercises in a stage had been performed, progression to the next stage should take place. When stage 4 exercises are able to be completed with acceptable pain, full return to sport can commence (Breda et al., 2020).
Cook, J., & Purdam, C. (2009). Is tendon pathology a continuum? A pathology model to explain the clincal presentation of load-induced tendinopathy. British Journal of Sports Medicine, 43(6): 409-16.
Defrate, L. E., Nha, K. W., Papannagari, R., Moses, J. M., Gill, T. J., & Li, G. (2007). The biomechanical function of the patellar tendon during in-vivo weight-bearing flexion. Journal of biomechanics, 40(8), 1716–1722. https://doi.org/10.1016/j.jbiomech.2006.08.009
Malliaras P., Barton C., Reeves, L., Langberg, H. (2013). Achilles and patellar tendinopathy loading programmes. Sports Med; 43(4): 267-286.
Naugle, K., Fillingim, R., Riley, J. (2012). A meta-analytic review of the hypoalgesic effects of exercise. The Journal of pain, 13(12): 1139-50.
Scott A., Squier K., Alfredson H., Bahr, R., Coombes, B., de Vos, R., Fu, S., Grimaldi, A…Zwerver, J. (2019). ICON 2019: International scientific tendinopathy symposium consensus: clinical terminology. Br J Sports Med: 54 (5); pg 260–262. doi:10.1136/bjsports-2019-100885 pmid:http://www.ncbi.nlm.nih.gov/pubmed/31399426