11 Jun Patella Tendinopathy – Often underloaded with insufficient intensity
What is patella tendinopathy?
Patella tendinopathy describes an overuse injury affecting the (yes you guessed it) patella tendon and knee generally. It typically happens gradually with repetitive loading, but there are instances of acute tendon issues from a very intense bout of tendon stress. Despite its name, the patella tendon is essentially a ‘ligament’, because it doesn’t attach muscle to bone – rather it attaches to 2 bones: the bottom of the patella (kneecap) and the top of the tibia (shin bone). This condition is also known as ‘jumpers knee’, alluding to risk factors of too much cutting/jumping, large demands on the knee extensors (quadriceps) and energy storage/release activities, beyond the tendon’s coping capacity.
Clinical features of patella tendinopathy
First and foremost, PAIN OVER THE INFERIOR POLE OF THE PATELLA (bottom of the kneecap where the patella tendon attaches) is the main diagnostic feature. If you’re experiencing pain in the middle section of the ‘tendon’ between the bony landmarks, there’s a high likelihood its more of a diffuse knee/bursa issue rather than a true patella tendinitis/tendinopathy. Other clinical features include: load dependency (hurts after too much load, often worse 1 day after), pain is worse with increased knee flexion angle (loaded deeper squat/lunge, and even prolonged sitting), stiff to warm-up early morning and gets a bit better with light movement, and pain is MINIMALLY associated with global knee swelling.
Various stages of patella tendinopathy
Well studied models suggest that tendinopathy occurs through a spectrum from normal tendon to pathologic tendon. The three phases included in the continuum model are: reactive/irritable tendinopathy, tendon dysrepair and degenerative tendinopathy. The following definitions were adapted from Cook & Purdam 2009.
Reactive tendinopathy occurs in response to acute tensile or compressive overload. In this stage, there is a non-inflammatory proliferative cell response in the cell and tendon matrix. The increase in the cell and tendon matrix increases the cross-sectional area of the tendon, which decreases the stress on the tendon in the short term. The changes at this stage to the tendon are reversible with reduced loading or sufficient rest.
The tendon dysrepair stage is a failed attempt at tendon healing. With chronic overloading of the tendon, there is continued production in the cells and tendon, which results in an accumulation of fluid in the extracellular matrix. This leads to the separation of collagen and disorganization in the extracellular matrix. Some of the changes in this stage are reversible.
The final stage is degenerative tendinopathy, which is characterized by cell apoptosis and extensive matrix disorganization due to chronic overloading. There is also neovascularization in the degenerated tendon. The changes at this stage have little capacity to revert to normal tendon. While pain can occur at any stage of tendinopathy, it is not associated with structural changes in the tendon. Therefore, pain management is possible at each stage of tendinopathy.
Treating patella tendinopathy: All about load
After the initial angry tendon stage, whereby minimal activity would aggravate pain for days at a time (you should unload during this stage and even use anti-inflammatories as required), it’s time to rebuild the tendon. TENDON’S LOVE LOAD! There have been many protocols created to treat patella tendinopathy over the years, with research noting that good outcomes have come out of 3 main ones: heavy slow resistance, progressive loading into short-shortening cycle, and supramaximal eccentric. One could argue that a combination of all of these would be the best way to approach individual presentations of patella tendinopathy for a variety of lifestyle and sporting demands. Something unhelpful within the physiotherapy and primary healthcare community is the almost ‘babying’ of patient’s with a more stable patella tendinopathy in early-mid dysrepair/degenerative stages (~3months of pathology). During this stage, the knee will still be hypersensitive and pain is certainly going to exist with activity – but we need to trust the physiological parameters and educate patients that the pain does not equal ongoing tendon damage. There needs to be a shift away from lunges with 3kg in each hand, bodyweight stepdowns, theraband knee extensions, and 10kg goblet squats – just because these exercises may be pain free for the patient doesn’t mean you’re doing anything for the tendon health!
The rehab continuum
First and foremost, by far the most essential muscle group to train during patella tendon rehabilitation is knee extensors. Namely: vastus medialis, vastus lateralis, rectus femoris, and slightly deeper is vastus intermedius. These 4 muscles make up what we call the QUADripceps.
Initially we may use isometrics for some analgesic benefits. This exercise type strengthens the quads in a certain range without changing muscle length (and potentially overstretching/irritating the tendon acutely). Options: wall sit, Spanish squat holds, isometric leg press bottom position.
Once pain levels are low and stable, and there is notably increased quad strength and control, we then prescribe some slow knee extension isotonics in mid ranges – then progressing to full range. Options: step ups, lunges, squatting, single leg skater squat decline board step downs +/- load.
After motor patterning of quads/lower kinetic chain has normalized and pain is more stable, it’s time to really bump up load and intensity which is the most evidence-based approach for tendinopathy. We can do heavy slow back squats, knee extensions (machine) bilateral or unilateral, multidirectional loaded lunges +/- heel hover, leg press. THESE NEED TO BE HEAVY AND INTENSE TO GAIN THE MOST REHABILITATION BENEFIT.
We then progress to some stretch shortening and plyometrics before return to sport. This may involve deeper knee flexion angles and more rapid contraction speeds.
Options; plyometric trap bar dead jumps, smith machine jump squats, reverse lunge/knee drive with landmine load, split squat jumps, etc.
Also make sure to include other major muscle groups to improve lower limb functional control and resilience: heavy hip thrust or single leg bridge, nordic/heavy knee curls, heavy seated and standing calf raise.
The bulk of patella tendinopathy research supports progressive overload and higher intensities for ideal outcomes. We educate patients that pushing toward a pain score of ~4-5/10 during exercise and reassessing if your body is adapting to that stress (less pain 1day after), is the best way to go about progressive overload. There should also be a steady plan of increasing weight used for isotonic exercises (+3% of load weekly is a good start) alongside an averaged overall workout intensity of ~8/10RPE (rate of perceived exertion). Otherwise we won’t be providing adequate stress for tendon adaptation!