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EDITORIALS: C Niek van Dijk and Willem M van der Tempel Patellofemoral pain syndrome BMJ 2008; 337: a1948 [Full text]

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Patellofemoral Pain Syndrome: Important Considerations

Bill Vicenzino, Natalie Collins, Kay Crossley, Thomas McPoil   (31 October 2008)

Corresponding email address

Willem M. van der Tempel, Postbus 22660, 1100 DD Amsterdam   (4 November 2008)

Patellofemoral Pain Syndrome: Important Considerations 31 October 2008
Bill Vicenzino, Chair in Sports Physiotherapy and Head of Physiotherapy School of Health and Rehabilitaiton Sciences, The University of Queensland, 4072, Qld, Australia, Natalie Collins, Kay Crossley, Thomas McPoil Send response to journal: Re: Patellofemoral Pain Syndrome: Important Considerations	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
Corresponding email address 4 November 2008
Willem M. van der Tempel, surgical house officer Academic Medical Center Amsterdam, Postbus 22660, 1100 DD Amsterdam Send response to journal: Re: Corresponding email address	The corresponing email address is incorrect and should be: c.n.vandijk@amc.uva.nl. Also note the phrase 'Physiotherapy and foot orthoses available without prescription are ...' in the opening paragraph. The words "without prescription" haven't been used by the authors. In the Netherlands foot orthoses and physiotherapy are usually only available with prescription. We suppose this is the same in most other countries. Competing interests: None declared