Influence of the hip on patients with patellofemoral pain syndrome: a systematic review. (2011)

Abstract
CONTEXT:
Patellofemoral pain syndrome (PFPS) is one of the most common conditions limiting athletes. There is a growing body of evidence suggesting that dysfunction at the hip may be a contributing factor in PFPS.
DATA SOURCES:
MEDLINE (1950-September 2010), CINAHL (1982-September 2010), and SPORTDiscus (1830-September 2010) were searched to identify relevant research to this report.
STUDY SELECTION:
Studies were included assessing hip strength, lower extremity kinematics, or both in relation to PFPS were included.
DATA EXTRACTION:
Studies included randomized controlled trials, quasi-experimental designs, prospective epidemiology, case-control epidemiology, and cross-sectional descriptive epidemiology in a scientific peer-reviewed journal.
RESULTS:
PFPS is associated with decreased hip strength, specifically at the abductors and external rotators. There is a correlation between PFPS and faulty hip mechanics (adduction and internal rotation).
CONCLUSIONS:
There is a link between the strength and position of the hip and PFPS. These patients have a common deficit once symptomatic. Hip strengthening and a coordination program may be useful in a conservative treatment plan for PFPS.

My comments:
This was a pretty informative review paper that summed up a growing body of research showing hip abduction and hip external rotation weakness is turning out to be more strongly associated with patellofemoral pain than any other factors.  Less so but still important however were associations with weakness in hip extension, hip internal rotation, knee flexion and knee extension.

So basically if if you have patellofemoral pain you probably want to add some progressive resistance exercise throughout your hips and legs (and I’d add some core in there too), but an emphasis on hip abduction and external rotation strength is probably a good idea. What’s interesting is that this paper illustrates the importance of hip strength on pain and function at the start of knee problems, and it turns out to be really important nearer the finish as well.