How To Rehabilitate Your Patellofemoral Pain
Patellofemoral pain or kneecap pain is a common occurrence in runners. It has even commonly been called ‘runner’s knee’. Almost 50% of running injuries occur at the knee, of which 48.8% occur at the patellofemoral joint (1). Luckily with the right advice, modifications and exercises even the most difficult cases of patellofemoral pain can be resolved.
Presentation and Diagnosis Of Patellofemoral pain
Patellofemoral pain (PFP) presents as pain at the front of the knee. It can be felt directly underneath the kneecap (patella) or in a vague location surrounding the kneecap. Typically it is not a pain you can put your finger on and say ‘that’s it I’m touching.’ It is typically aggravated by activities that increase load of the patellofemoral joint (PFJ) such as lunging, squatting, descending stairs, running and prolonged sitting (2). Individuals with PFP may also describe or experience crepitus from the joint (a clicky knee), some tenderness on and around the outside of the kneecap and a small amount of swelling (3, 4). Patellofemoral pain does not typically occur from a single incident or moment (such as twisting or bending) however can come on after one particular run.
The diagnosis of patellofemoral pain is made through a thorough history and objective assessment. The imaging modalities x-ray and MRI can assist in viewing the structure of the PFJ and rule out other possible diagnoses. However an MRI is very rarely necessary for the management of patellofemoral pain and commonly doesn’t alter clinical management. This is largely due to the very inconsistent link between structure at the knee joint and pain (3). The absence of association between changes in cartilage at the joint and PFP challenges the assumption that a patient’s pain can be explained by structural changes in isolation (5, 2). This can be great news for those with significant cartilage changes at the knee joint, edema and or knee osteoarthritis as even though your images may reveal this; it doesn’t mean you can’t have a painfree highly functioning knee. The current concepts regarding how one arrives at developing patellofemoral pain is through the complex interaction of structure, biomechanics (expanded upon below), tissue homeostasis (overload or under-loading of the PFJ) and non-mechanical factors (2). Non-mechanical factors such as elevated levels of anxiety, depression, catastrophising and fear of movement have also been reported in individuals with PFP, which have the capacity to negatively influence physical function and activity related behaviours (6).
There are a number of potential factors that can alone; or in combination lead to PFP.
1. Training Loads
Training loads are potentially the most common reason someone presents with onset of PFP, through a combination of too much, too quick too soon. This can be total running, speed or hills; or a normal amount after time out. Training loads are also more than the amount of running but also the intensity and terrain. Even with training loads being held steady onset can occur with ‘under recovery,’ where normal training loads cannot be tolerated due to multiple occurrences of poor/reduced sleep, extra stress, reduced energy intake and or illness. This is well summarised in the diagram below. Outside of normal training loads, large changes to the amount of daily stress to the PFJ may play a role in development of symptoms, such as large increases (or decreases) in the amount of ascending and descending stairs and hills, increased deep squatting, increased bike riding, changes to or improper bike set-up.
2. Biomechanical Factors
There are numerous biomechanical factors that have been linked with PFP. In some instances these deficits may exist prior to the development of symptoms, potentially representative of the primary driver of symptoms or in combination with other contributing factors (7). PFP development is more common in individuals with reduced knee extension strength (8) and those with symptoms have reduced quadriceps cross sectional area (9). This size and strength loss however appears to be less apparent in adolescents with PFP(1).
Other factors above and below the knee include contralateral pelvic drop, internal femoral rotation, knee valgus, internal tibial rotation and foot pronation. For example statistically individuals with PFP are reported to demonstrate a more pronated foot posture (8). It is proposed that a combination of these biomechanics can lead to altered or increased loads at the PFJ (10). These factors can however be a runners natural biomechanics (certainly there are elite runners with this) well prior to onset of symptoms so are not necessarily causative of pain. Often during treatment (see below) one or more of these biomechanics aspects may be modified to see if it has favourable effects on pain. A higher number of the biomechanical alterations were strongly associated with higher levels of pain and lower functional status (11). Therefore a comprehensive look at biomechanics alongside the overall picture will help identify their potential importance.
Source: Adapted from Ref. (69). Powers CM. The influence of altered lower-extremity kinematics on patellofemoral joint dysfunction: a theoretical perspective. J Orthop Sports Phys Ther. 2003;33(11):639-646.
3. Running Technique
There are a number of variables related to running technique which have been linked to PFP. Overstriding and high vertical displacement have been linked to increasing stress on the PFJ (3). The technique and biomechanics of greater hip adduction and internal rotation (see picture above) also appears to have some significance in PFP (12, 13). These technique factors can be modified through gait retraining (see treatment below). Strength work has commonly been implemented to modify variables such as lateral hip drop, hip adduction and hip internal rotation however may not significantly change these in many cases. Hence why these strength exercises are often done in combination with trialling modifications to running technique. There are also many high level male and female runners who naturally run with technique that involves large amounts of hip internal rotation and hip adduction despite having no significant pain or injury (for example look at video of elite runner Priscah Jeptoo). This highlights that for some people it can be a significant contributor or avenue of treatment and others perhaps less important.
The first essential step in treating patellofemoral pain is understanding the diagnosis, what matters and what doesn’t and the contributing factors that are specific to you. If you’ve read this far hopefully you have a headstart into understanding and managing PFP.
2. Activity Modifications
In treating PFP it is important to quickly establish how sore and irritable the knee is. If day to day symptoms are low (say 2-3 out of 10) and or only happen during running at a certain speed or distance our management will differ from the person who has 5/10 pain and can only run 200m before it forces them to stop. It is more commonly safe to continue running (with certain technique modifications if needed) within what volume is pain free or produces a low level of symptoms. If symptoms flare up after a run significant then running volume may need to be further dropped, shifted to Alter-G anti-gravity treadmill or ceased (and commence cross-training temporarily). If symptoms can be quickly reduced by reducing what is most painful then often the runner can progress quicker and more confidently. For example if the PFP is aggravated by squats and lunges, these exercises can be modified; if stairs are a painful trial a week of taking the lift. In essence changing the simple things so day to day pain is minimised can be helpful.
3. Gait Retraining (Changes to Running Technique)
As described above certain elements of running technique can increase stress on the PFJ (overstride, high vertical displacement, increased adduction and internal rotation). Increasing a runner’s cadence by 5-10% can not only reduce overstriding, but reduce vertical oscillation, patellofemoral joint stress and pain (4, 14-17).
Other elements of gait retraining may include mirror feedback and cues to try reduce hip adduction and internal rotation; such as “push their knees outwards,’ ‘maintain some distance between your knees, (18). Often significant changes in pain can be felt whilst running as they change their gait. Other less commonly used changes include manipulating footstrike and trunk lean (18). One must be cautious when beginning to change too many things as load often shifts from area to another, potentially causing other symptoms. There have been studies which have reported calf pain, achilles tendon or forefoot pain when changing footstrike quickly or without proper conditioning (19-20).
4. Symptom ‘Modifiers’
Symptom modifiers as those short term things that give you relief or ‘modify’ your pain. What we are looking for are mechanisms or tools to reduce your pain quickly. For example taping the knee or foot might significantly reduce pain when going downstairs or running. An orthotic (custom or off the shelf) may reduce your knee pain (21). Other tools such as massage, stretching or icing may also help provide relief or aid settling your pain. This can then help maximise the amount of training you can do and make exercise more comfortable.
Exercise is a crucial part of the rehabilitation progress. Based on current evidence and clinical practice, exercise therapy forms the cornerstone of management for PFP (22-24, 5, 13). Findings from recent systematic review indicate that proximally (trunk, glutes) targeted exercise, when added to knee targeted exercise (eg quads), may improve symptoms and function in the short (< 3 months), medium (3-12 months) and longer term (> 12 months) (24). Additionally, in the early stages of rehabilitation (first 6 months), proximally targeted exercise may improve pain and function to a greater extent than knee targeted exercise. This is probably in part due to exercise selection of knee focused exercises can sometimes exacerbate symptoms if not chosen carefully. Despite pain or MRI findings there are a variety of exercise options that can be implemented and progressed to help rehabilitate your knee pain.
The exercises are primarily strengthening based combined with motor control exercises. Motor control exercises are those which are lighter loads but are focused on control of foot, hip, knee, and or trunk positioning to help modify patterns of movement to ultimately reduce pain. For example performing a lateral step down with a cue to keep the knee outward might reduce PFP. Additional cues might include controlling the arch of your foot. These cues can be applied to many double leg and single leg exercises such as squats, lunges and step ups and may reduce pain at the knee.
A) Before cueing B) After Cueing
There is no recipe approach for rehabilitation exercises with many variations achieving overall strength and control goals and return to full function. Typical rehabilitation will address all major lower limb and trunk muscles and all major movement patterns progressing from lighter to heavier and/or faster movements. Small modifications to common exercises can make a significant reduction in knee pain, by reducing stress on the PFJ and changing targeted muscles. These can then be modified over time to return to normal exercises and training. Below are a few examples that may be more comfortable; please see your Physiotherapist for a more thorough and individualised program.
Reducing the amount of forward knee movement (knee less over toes), knee valgus (niward movement) or the depth of the squat can be the first trial to change symptoms. Alternatives include a Banded squat (knees out into the band) (A), glute dominant squat (increased forward lean)(B) or Sumo Squat (C).
Lunge or Split Squat:
Again reducing the amount of forward knee movement (knee less over toes), knee valgus (inward movement) or the depth of the lunge or split squat can be the first trial to change symptoms. An alternative is a more hip dominant forward lean variation.
Progressively more hip dominant lunges.
Reduce inward knee movement.
Banded knee extensions or with the knee extension machine in the gym can be sore for people with PFP yet also great for quads strength. Often choosing the middle range and performing small reps or holds can be more comfortable (place a rolled towel under the knee). Start and finish the exercise with 2 legs before shifting to 1 leg for the small reps, this helps to reduce some stress on the knee joint.
A gradual increase in running volume is an important part of rehabilitation. Running itself places stress on the patellofemoral joint and therefore at a certain level knee symptoms can increase. Many runners can continue to run whilst having PFP but may have temporary drops in volume, speed or hills. Gradual increases in overall running volume, speed and hills are important in ensuring pain flare ups are minimised. There are no hard and fast rules on how this is achieved but is often done on an individual level depending on time out of running, past training history, previous volume, knee symptoms and irritability and training goals. Many runners who go from no running straight back to normal training volume and intensity often experience knee pain again.
Lewis Craig (APAM)
Masters of Physiotherapy
Featured in the Top 50 Physical Therapy Blog
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