Key Points
- Weakness in the hip muscles is one contributing factor to patellofemoral knee pain.
- Hip and knee strength exercises are more effective in reducing pain and improving activity in individuals with patellofemoral pain than knee strengthening exercises alone.
- Strength training for the hip and knee muscles should be conducted thrice weekly for six weeks.
What causes knee pain
Pain in the front of your knee. It could be PFPS
Patellofemoral pain (PFPS) refers to pain in the front of the knee, especially under the kneecap.
Knee pain when squatting or climbing stairs
The pain in the front of the knee can present as a nagging ache or an occasional sharp twinge and is usually felt after squatting, climbing stairs, running, and sitting for a long time. The incidence and prevalence of PFPS have not yet been determined, but it is considered one of the most common musculoskeletal conditions seen in general practice and sports medicine clinics.
The pain associated with PFPS not only decreases short-term performance in daily activities but can also affect social activities in the long term should the pain not subside. This is pretty common too, with 90% of people suffering from PFPS reporting pain lasting up to four years after the first symptom occurred. One in four patients with PFPS also reports significant symptoms lasting up to even 20 years!
Despite the severity of PFPS in influencing one’s life, much is not known about the causes of PFPS. It is believed that the development of PFPS may be caused by a combination of factors, rather than a single factor. These factors can be classified into:
- Local factors: Affect the knee joint and its surrounding tissues. Examples: Altered joint mechanics and compromised quadriceps function.
- Global factors: Affect the mechanics of the hip and ankle joints. Examples: Increased foot pronation and increased hip adduction and medial rotation, especially during weight-bearing tasks.
Poor hip and knee strength
Because PFPS is a knee condition, many may wonder why the hip should be considered. To move, the hip, knee, and ankle work together as a unit. Therefore, as mentioned above, the altered patterns or strength of the joints above and below the knee (ie. the hip and ankle) can contribute to pain. These fall under “nonlocal factors” that cause PFPS.
Weakness in the hip musculature is thought to result in an imbalanced muscle tone, and therefore abnormal hip movements. Specifically, weakness in the hip abductors, lateral rotators and extensors results in excessive hip adduction and medial rotation. This leads to altered knee joint kinematics and increased knee joint stress, resulting in the pain felt.
Simply put, if the hip muscles are not strong, the knee will tend to collapse inwards, thereby increasing the load on the knee cap, causing pain.
The natural question would therefore be: what are the helpful exercises to help manage my knee pain?
Helpful exercises for front of knee pain
Historically, rehabilitation for PFPS focused solely on the knee and the local factors, such as exercises to strengthen the quadriceps muscle. Knee strengthening exercises are effective in increasing the knee joint contact area and help to ease the pain. Beyond exercise, knee orthoses such as kneecap taping and bracing were also used, though there was a lack of evidence supporting their use.
Recently, there has been some evidence supporting the inclusion of hip strengthening exercises in PFPS rehabilitation. Exercises which target the strengthening of specific hip muscle groups, namely the hip abductors, lateral rotators and extensors, can help reduce patellofemoral joint stress and relieve pain. These exercises may be performed with or without knee strengthening exercises, although a combination of hip- and knee-targeted exercises would further improve functional outcomes and pain.
Hip- and knee-strengthening exercises can be performed using body weight, free weights, machines, or elastic resistance. Initially, one would start with light weights or body weight and gradually progress to heavier weights. Examples of hip- and knee-strengthening exercises include:
How can exercise help reduce the pain in the knee?
A 2018 systematic review studied the effectiveness of hip and knee strengthening in reducing pain, increasing activity levels and increasing strength. They compared individuals who underwent both hip and knee strengthening with those who only did knee strengthening and those who did neither.
When compared to no strengthening program, people who underwent hip and knee strength training had significantly reduced pain and improved activity. Additionally, these benefits were maintained after one year in individuals who received hip and knee strength training. However, there was no significant change observed in terms of strength between those who attended hip and knee strength training and those who did not.
When compared with individuals who only attended knee strength training, those who received both hip and knee strength training reported significantly reduced pain and improved activity. Similarly, these benefits were maintained 12 weeks after the strength training had ended for people who had hip and knee strength training. There was also no significant change in strength observed between both groups.
In other words, hip and knee strengthening is effective in reducing pain and improving activity in individuals with patellofemoral pain. When performing both strength training together, there is a greater decrease in pain and improvement in activity compared to knee strengthening alone. These benefits are also maintained even after the termination of strength training.
The improvements in pain and activity may be linked to the addition of weight-bearing exercises, such as squats. These exercises can be beneficial for the lower-limb pattern of motion and ankle flexibility, which positively influence nonlocal factors contributing to PFPS. In addition, strength training may have unintentionally contributed to increased hip and knee muscle endurance, especially if the training intensity and repetitions fall under the recommended parameters for endurance training. Thus, this may explain the increase in functional levels, as these people who had hip and knee strength training were able to tolerate longer bouts of daily activities without feeling pain or fatigued.
How long should these exercises be done for?
For individuals with moderate-to-high levels of PFPS, strength training for the hip and knee muscles should be conducted thrice weekly for six weeks. This is the training level effective for decreasing pain and improving activity.
For strength improvements, a longer duration of strength training is required to see an increase in strength. Most muscle adaptations occur between eight and 12 weeks of training. Therefore, changes in strength were not significant as observed in the review as the average duration of strength training was only six weeks.
Unsure of what to do? Contact us at The Rehab Centre and our Physiotherapist will be able to ascertain the source of pain and have it addressed early!
Ref:
Nascimento LR, Teixeira-Salmela LF, Souza RB, Resende RA. Hip and Knee Strengthening Is More Effective Than Knee Strengthening Alone for Reducing Pain and Improving Activity in Individuals With Patellofemoral Pain: A Systematic Review With Meta-analysis. J Orthop Sports Phys Ther. 2018 Jan;48(1):19-31. doi: 10.2519/jospt.2018.7365. Epub 2017 Oct 15. PMID: 29034800.
DISCLAIMER: These advise and exercises should not replace the need for a consultation with a Physiotherapist especially if your condition doesn’t improve. Therapeutic exercise should be carefully selected to suit your condition.
On front of knee pain…people also asked
Knee pain when running?
Running is….great! Don’t let anyone convince you otherwise. Of course, you need to train and be strong in order that you’re able to cope with the load running brings along.
If you’re new to running, the knee will not be able to cope with the load, hence you might experience pain in the front of your knee.
Similarly, even though you’re seasoned runner, you will also need to have the required strength and control in your hip and knee so that your will be able to cope with the running load.
No one, absolutely no one, is exempt from strength training!
What is the best painkiller for knee pain?
You ready for this? There is none! There are various causes to knee pain and truth be told, your best bet is to seek help from a Physiotherapist first so that we will be able to ascertain the source and cause of your pain.
Painkillers, well, there merely hide the problem. Your pain will likely persists!
Pain in back of knee when bending?
Great question! Back of knee pain when bending is usually due to a hamstring or calf strain. It usually occurs with PFPS because when the front of your knee hurts, the quadricep msucles may be affected and not function as they are required.
As a result, the hamstring and calf has to work harder, and thereby cause pain after being overworked!
The solution? Find out if indeed you have PFPS. Address it and the back of your knee pain will be addressed!