Patellofemoral pain syndrome is a condition that is commonly encountered by the sports physiotherapist. There is a clear reason for this, it has been reported to affect approximately 25% of athletes (DeHaven & Lintner, 1986). Furthermore, it is the most commonly reported injury sustained by runners (Taunton et al., 2002). Thus, it is the subject of much discussion on this site, as we have provided articles on a number of management options for patellofemoral pain syndrome, including:
However, this article will discuss new research on potential prospective indicators for the development of patellofemoral pain syndrome.
Why Do We Care About Prospective Predictors of Patellofemoral Pain Syndrome?
There are many important reasons why the sports physiotherapist would care about identifying prospective indicators. Whilst we all know patellofemoral pain syndrome is frequently well managed by comprehensive physiotherapy or physical therapy, many patients remain symptomatic long after diagnosis.
As we often say: prevention is better than cure! Therefore, if the sports physiotherapist can identify those who are at high risk of developing patellofemoral pain syndrome, they may be able to implement interventions aimed at preventing its development.
Thus, a new systematic review and meta-analysis may provide some assistance in predicting those who are at risk of developing patellofemoral pain syndrome (Pappas & Wong-Tom, 2012). Pappas and Wong-Tom (2012) included 7 articles in their systematic review, and evaluated the prospective influence of many variables on the development of patellofemoral pain syndrome. And this is what they found…
What Factors Predicted the Development of Patellofemoral Pain Syndrome?
The following were prospective predictors for the development of patellofemoral pain syndrome:
- Muscle Strength: those with lower isometric knee extension strength were more likely to develop patellofemoral pain syndrome.
- Muscle Flexibility: those with reduced quadriceps and gastrocnemius flexibility were more likely to develop patellofemoral pain syndrome.
- Dynamic Foot Posture: those with a higher navicular drop were more likely to develop patellofemoral pain syndrome.
- Landing Biomechanics: those with excessive knee valgus during landing were more likely to develop patellofemoral pain syndrome.
- Physical Testing: those with reduced vertical jump performance were more likely to develop patellofemoral pain syndrome. As you may suspect, this is possibly related to reduced knee extensor strength.
What Factors Did Not Predict the Development of Patellofemoral Pain Syndrome?
The following were, in some cases quite surprisingly, not predictive of the development of patellofemoral pain syndrome:
- Anthroprometric Measures: including height, weight and BMI.
- Hamstring Flexibility
- Static Foot Posture: as measured by the Foot Posture Index.
- Static Lower Limb Alignment: including knee valgus, varus and Q-angle.
- Lower Limb Joint Laxity: including hip rotation, knee extension and passive patellar mobility.
Prediction vs. Pathogenesis: A Word of Warning
The authors make it clear that there is a difference between factors that are prospective predictors and those that are pathogenetic. For example, whilst measures of passive patellar mobility were not predictive of a patient developing patellofemoral pain syndrome, it may still be a pathogenetic factor in a patient who presents with the condition. Make sense?
Limitations of The Research
As we tend to see frequently, there are limitations to this research. Unfortunately, the systematic review showed:
- Few quality studies included
- Heterogeneous patient groups
- Lack of consensus; some studies disagreed with each other
Clinical Implications of This Research
There are some simple clinical implications from this research. There is consensus in the literature that those with reduced knee extensor strength, muscle flexibility in quadriceps and gastrocnemius, poor dynamic foot and knee biomechanics, and vertical jump performance are at higher risk of developing patellofemoral pain syndrome.
As such, the development of interventions aimed at addressing and correcting these musculoskeletal and biomechanical contributors may reduce the development of patellofemoral pain syndrome in high risk groups. These factors may also form an integral part of athlete ‘pre-screening’.
What Are Your Thoughts?
What do you think about this new research? Does it echo what you find in your clinic or when pre-screening your athletes? I would love to know, so be sure to let me know in the comments or catch me on Facebook or Twitter.
Are you a physiotherapist or physical therapist looking to promote your own clinic on our site? Check this out!
DeHaven KE, Lintner DM. Athletic injuries: comparison by age, sport, and gender. Am J Sports Med. 1986;14(3):218-224.
Devereaux M, Lachmann S. Patello-femoral arthralgia in athletes attending a sports injury clinic. Br J Sports Med. 1984;18(1):18-21.
Pappas E, Wong-Tom WM. Prospective predictors of patellofemoral pain syndrome: A systematic review with meta-analysis. Sports Health: A Multidisciplinary Approach 2012 4: 115
Taunton JE, Ryan MB, Clement DB, et al. A retrospective case–control analysis of 2002 running injuries. Br J Sports Med 2002;36:95 – 101.
Photo Credit: Dru Bloomfield – At Home in Scottsdale
Trey PT says
The research did not mention the Glut Max & Med weakness as predictive factors but from a biomechanical stand point it would seem to be very important. Has there been many good studies regarding this? Also, in the research above, how was isometric extensor strength tested? I’m guessing isokinetically and then put in terms of “% of body weight”, or was it an absolute number?