Patellofemoral pain syndrome

Professors van Dijk and van der Tempel[1] have written a good
overview of the topic area, our clinical trial[2] and the need for future
work to incorporate a no-treatment control group. We would like to comment
on a few of the points they raise in their editorial.

1. The relationship between flat foot deformity and patellofemoral
pain syndrome is a widely held clinical notion/observation that is not
strongly supported by research (e.g., [3 ,4]). As such, we were careful
not to endorse this association in our write-up, and encourage readers to
exercise care when taking this point on board. Aside from there being
little concrete evidence of the link between flat feet and patellofemoral
pain syndrome, there is also the issue of a lack of consistent and solid
evidence underpinning the notion that orthoses support the arch and
control excessive pronation (flat feet) and thus alignment of the lower
limb and patella. Our clinical trial shows that foot orthoses with inbuilt
arch support and inversion (supination/varus) wedging/posting are superior
to flat shoe inserts made of the same material. We feel that this provides
evidence that there is some therapeutic property in the shape and
contouring of the orthoses. This requires further evaluation, so that the
therapeutic characteristics and underlying mechanisms of action of foot
orthoses become more evidence-based.

2. We have recently published a follow up study that may provide some
support for the notion that the orthoses are likely to be more effective
in specific individuals[5]. In this study we detail a clinical prediction
rule in which 3 of the following 4 patient characteristics can be used to
improve the likelihood of marked improvement at 12 weeks from 40% to 85%:
(i) age > 25 years, (ii) height <165cm, (iii) pain severity <
53mm on 100 mm VAS, and (iv) mid-foot width difference from non weight
bearing to weight bearing > 11mm. The mid-foot width difference of >
11mm, which can be easily measured with a vernier caliper[6], identifies
those who have greater mobility of the foot when it is loaded in weight
bearing, which is a component of excessive foot pronation. This may
provide some support to the notion enunciated in 1 above.

3. The need for future studies to include a group which follows a
'wait and see policy', as in previous randomised clinical trials (RCTs) of
musculoskeletal pain[7 ,8], is a valid point and one we support in
principle. Enacting such arms of RCTs is often perceived to be an
impediment to recruitment and gaining ethical approval, and may compromise
the trial‚s successful completion. Notwithstanding this, it is important
to understand that the natural history of many musculoskeletal pain states
(or time course of resolution of acute bouts of pain) are largely not
described and so it is difficult to know if some minimal attempt at
intervention (e.g. flat insert) is better than just waiting for
resolution. If we assume that flat inserts provide some Œplacebo effect‚
beyond natural resolution in the short term, then the use of foot orthoses
is likely to speed up resolution beyond that of natural recovery. Many of
our patients present to clinics with patellofemoral pain that has not
resolved, often after a period of waiting and seeing, and for which they
are seeking a speedy resolution of their pain and subsequent return to
pain-free function. In this regard, the findings of this study, and
previous studies that show physiotherapy to be more effective than placebo
in the short term, provides solid direction to both the patient and
practitioner in their quest to return as soon as possible to pain-free
participation in life.

4. The editorial makes two pertinent statements, that patellofemoral
pain „usually resolves over time‰ and „tends to become a chronic problem‰.
The literature tends to support the latter of these rather than the
former. A prospective longitudinal study found that 94% of 63 adolescent
females had ongoing pain two to four years after initial presentation,
while one in four had significant symptoms up to 20 years later[9]. Cross-
sectional studies report mean patellofemoral pain durations of 43 months
(range 6 to 108) [10] and 8 years (range 1 to 25). The median duration of
knee pain of our RCT cohort reflected this chronic tendency (28 months
(interquartile range 12 to 84))[2]. Our finding that individuals with
patellofemoral pain have considerable symptom duration suggests that the
condition does not spontaneously resolve

5. There are a few minor points that we feel should be further
clarified for the reader:

(a) The study by Wiener-Ogilvie & Jones [11] was a pilot trial
that was substantially underpowered to detect any between-group
differences. Hence, to summarise their data as evidence of no effect is
problematic as there is a high likelihood of a type II error (that is,
accepting that there is no effect when in truth/fact there is an effect).

(b) The editorial makes a summarising statement that our trial
confirms the good results of exercises and orthoses in the short term and
cites Crossley et al[12], presumably in support of that statement. It is
erroneous to do such, as Crossley and colleagues evaluated a multi-modal
physiotherapy treatment that included exercise and tape, but not foot
orthoses. Our study was the first adequately powered, high quality RCT to
provide point estimates of effect that favoured orthoses over flat inserts
in the short term.

(c) We note a reference to orthoses being used without prescription
in the opening paragraph that may be misinterpreted by the reader as to
mean that the orthoses used were applied by a lay person, possibly bought
across the counter of a retail outlet. This would be misleading as we used
qualified physiotherapists who received additional training to fit and
modify the orthoses following a predetermined algorithm (see [13 ,14] for
more information). In brief, the orthoses were prescribed on the basis of
fit and comfort in the first instance and then modified to improve pain-
free performance of a previously painful task. We propose that fitting of
orthoses in this way is likely best performed by a physiotherapist,
podiatrist or athletic trainer, but medical practitioners with a
predilection to using physical therapies should also be able to
effectively fit orthoses.

(d) The authors cite a recent systematic review that they state found
no evidence to support the use of any orthotic devices in patellofemoral
pain[15]. This conclusion is misleading, as all five included studies
evaluated knee orthotic devices, not foot orthoses. We performed a
systematic review and meta-analysis[16] of more recent publications, which
identified two small RCTs for foot orthoses in patellofemoral pain, one of
which was underpowered to detect between-group differences [11]. Although
the other study did not provide point estimates of effect for calculation
of effect sizes, the authors reported a significantly greater reduction in
patellofemoral pain in those treated with foot orthoses than the group
that received flat inserts [17]. This study was not included in the review
by D‚Hondt et al[15] due to a lack of statistical data.

References

1. van Dijk CN, van der Tempel WM. Patellofemoral pain syndrome. BMJ
2008;337(oct24_1):a1948-.

2. Collins N, Crossley K, Beller E, Darnell R, McPoil T, Vicenzino B.
Foot orthoses and physiotherapy in the treatment of patellofemoral pain
syndrome: randomised clinical trial. BMJ 2008;337(oct24_1):a1735-.

3. Powers CM, Chen PY, Reischl SF, Perry J. Comparison of foot
pronation and lower extremity rotation in persons with and without
patellofemoral pain. Foot Ankle Int 2002;23(7):634-40.

4. Witvrouw E, Lysens R, Bellemans J, Cambier D, Vanderstraeten G.
Intrinsic risk factors for the development of anterior knee pain in an
athletic population. A two-year prospective study. Am J Sports Med
2000;28(4):480-9.

5. Vicenzino B, Collins N, Cleland J, McPoil T. A clinical prediction
rule for identifying patients with patellofemoral pain who are likely to
benefit from foot orthoses: a preliminary determination. British Journal
of Sports Medicine 2008;doi: 10.1136/bjsm.2008.052613.

6. McPoil T, Vicenzino B, Cornwall M, Collins N. Variations in foot
posture and mobility between individuals with anterior knee pain and
controls. J Orthop Sports Phys Ther 2007;37(1):A15.

7. Bisset L, Beller E, Jull G, Brooks P, Darnell R, Vicenzino B.
Mobilisation with movement and exercise, corticosteroid injection, or wait
and see for tennis elbow: randomised trial. Bmj 2006;333(7575):939.

8. Smidt N, van der Windt D, Assendelft WJJ, Deville W, Korthals-de
Bos IBC, Bouter LM. Corticosteroid injections, physiotherapy, or a wait-
and-see policy for lateral epicondylitis: a randomised controlled trial.
Lancet 2002;359(9307):657-662.

9. Nimon G, Murray D, Sandow M, Goodfellow J. Natural history of
anterior knee pain: A 14- to 20-year follow- up of nonoperative
management. Journal of Pediatric Orthopaedics 1998;18(1):118-122.

10. Thomee R, Renstrom P, Karlsson J, Grimby G. Patellofemoral pain
syndrome in young women. I. A clinical analysis of alignment, pain
parameters, common symptoms and functional activity level. Scand J Med Sci
Sports 1995;5(4):237-44.

11. Wiener-Ogilvie S, Jones RB. A randomised trial of exercise
therapy and foot orthoses as treatment for knee pain in primary care.
British Journal of Podiatry 2004;7(2):43-9.

12. Crossley K, Bennell K, Green S, Cowan S, McConnell J. Physical
therapy for patellofemoral pain: a randomized, double-blinded, placebo-
controlled trial. Am J Sports Med 2002;30(6):857-65.

13. Vicenzino B. Foot orthotics in the treatment of lower limb
conditions: a musculoskeletal physiotherapy perspective. Man Ther
2004;9(4):185-96.

14. Vicenzino B, Collins N, Crossley K, Beller E, Darnell R, McPoil
T. Foot orthoses and physiotherapy in the treatment of patellofemoral pain
syndrome: a randomised clinical trial. BMC Musculoskelet Disord
2008;9(1):27.

15. D'Hondt NE, Struijs PA, Kerkhoffs GM, Verheul C, Lysens R,
Aufdemkampe G, et al. Orthotic devices for treating patellofemoral pain
syndrome. Cochrane Database Syst Rev 2002(2):CD002267.

16. Collins N, Bisset L, McPoil T, Vicenzino B. Foot orthoses in
lower limb overuse conditions: a systematic review and meta-analysis. Foot
Ankle Int 2007;28(3):396-412.

17. Eng JJ, Pierrynowski MR. Evaluation of soft foot orthotics in the
treatment of patellofemoral pain syndrome. Phys Ther 1993;73(2):62-8;
discussion 68-70.

Competing interests:
None declared