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Weak quads are the only factor that predicts of patellofemoral pain syndrome

PainSci » bibliography » Pappas et al 2012
Tags: etiology, structuralism, patellar pain, pro, biomechanical vulnerability, arthritis, aging, pain problems, knee, leg, limbs, patellofemoral joint, overuse injury, injury, running, exercise, self-treatment, treatment

One page on PainSci cites Pappas 2012: The Complete Guide to Patellofemoral Pain Syndrome

PainSci commentary on Pappas 2012: ?This page is one of thousands in the bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.

Many biomechanical causes for chronic anterior knee pain have been implicated in studies over the years, but usually only in cross-sectional studies that look at people who already have pain. This study reviewed only prospective studies: that is, studies of people don’t have pain at the start, and are then followed over time to see who develops the condition. This way you can measure a bunch of things at the beginning and actually see what might matter in the long run.

In this review, out of seven common scapegoats for PFPS — things like Q-angle, poor knee biomechanics when landing from a jump, and obesity — the only one that seemed to definitely increase one’s risk of developing anterior knee pain was weak knee extensor muscles (the quadriceps).

~ Paul Ingraham

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

CONTEXT: Patellofemoral pain syndrome (PFPS) is one of the most common overuse injuries.

OBJECTIVE: To assess the collective evidence of predisposing factors to PFPS.

DATA SOURCES: MEDLINE (1960-June 2010), EMBASE (1980-June 2010), and CINAHL (1982-June 2010).

STUDY SELECTION: Studies were included if patients were asymptomatic at baseline testing (free of PFPS) and were prospectively followed for the development of the disorder. Only studies that assessed at least 1 variable that can be measured at a typical clinic were included. After duplicates were removed, 973 studies were assessed from their titles or abstracts, 20 from the full text, and from these, 7 met the inclusion criteria.

DATA EXTRACTION: Data were extracted for age, weight, height, sample size, patient type (military vs civilian), follow-up periods, diagnostic methods, and diagnostic criteria. Means and standard deviations were extracted for all outcome variables.

RESULTS: Meta-analyses were performed for height, weight, leanness, Q angle, number of sit-ups, knee extension strength, and peak knee valgus angle during landing. Lower knee extension strength was the only variable that was predictive of PFPS (P < 0.01). Other variables that were identified as predictive of PFPS by single studies were vertical jump, push-ups, knee flexion and hip abduction strength, thumb-to-forearm flexibility, quadriceps and gastrocnemius flexibility, genu varum, navicular drop, knee valgus moment at initial contact during landing, social support, and palliative reaction.

CONCLUSIONS: It appears that anthropometric variables are not associated with PFPS, while knee extension strength deficits appear to be predictors of PFPS.

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