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A Clinical Investigation to Determine the Effectiveness of Biomechanical Foot Orthoses as Initial Treatment for Patellofemoral Pain Syndrome

Doug Pitman, MD
Doug Jack, CPO

ABSTRACT

This clinical investigation was undertaken to determine whether biomechanical foot orthoses (BFOs) can be used as first-line treatment of patellofemoral pain syndrome (PFPS) within a family practice/sports medicine office setting. During a 36-month period from November 1995 through October 1998, those patients meeting the criteria for diagnosis and treatment of PFPS were prescribed BFOs as a first-line treatment if their knee pain occurred before, during, and after exercise (grade 3 pain) or if their knee pain prevented athletes/patients from participating in any form of exercise (grade 4 pain). Six months after the BFOs were properly fitted, each patient was sent a questionnaire to determine the outcome of treatment. On a scale from 1 (least painful) to 10 (most painful), the weighted average preBFO level of pain was 7.34 and 6 months later the weighted average pain level was 2.46. The overall weighted average knee-pain reduction was 4.9 (67% across the full range of patients). On the basis of this retrospective investigation, there are firm indications that high-quality, consistently fabricated BFOs offer athletes/patients a cost-effective first-line mode of treatment for PFPS of moderate to severe degree.

Keywords: Patellofemoral pain syndrome, Q angle, functional pronation, biomechanical foot orthoses

Patellofemoral pain syndrome (PFPS) is one of the most common overuse injuries diagnosed and treated in sports medicine clinics.¹ The range of the problem is best understood by looking at the sports medicine epidemiology studies by Stephen Rice in Seattle-area high schools between 1980 and 1989. Dr. Rice found that the highest incidence of athletic injuries/1000 athletic exposures to be in cross-country runners (boys and girls) at 17.1 injuries/1000 athletic exposures.² The vast majority of these injuries were overuse injuries, with anterior knee pain accounting for a significant percent.³

PFPS is seen more commonly in girls than boys and in women than men and may approach a female-to-male ratio of 4 to 1.⁴ PFPS results in considerable lost time for those athletes participating in cross-country, track, recreational running, hiking, soccer, and basketball. Recreational sports involving uphill and downhill motion tend to exacerbate the problem significantly. Although the anatomical factors that are linked to the cause of PFPS have been expertly dissected by specific investigators,⁵ satisfactory treatment lags behind our understanding of the problem. A recent article by Nimon et al⁶ indicates that the problem of PFPS seems to have a self-limited course for young athletes, improving as adolescents move into adulthood. The prognosis for PFPS in a vast majority of patients is very good. However preadolescent and adolescent female and male athletes are playing with knee pain and losing valuable playing time as a result of PFPS.

The Q angle (Fig. 1 ) has been implicated as one of the major causative factors in creating a significant tracking problem for the patella in PFPS. The normal Q angle with relaxed quadriceps is considered to be up to 15 to 20 degrees in women and 10 to 15 degrees in men.⁵ Some consider the upper end of the Q angle in women to be 15 degrees and in men to be 10 degrees with contracted quadriceps (Fig. 2 ). The standard measurement for diagnostic purposes is made with relaxed quadriceps with the patient lying in a supine position with a straight knee.

The kinetic chain of the lower extremity from the foot through the subtalar joint and up to the knee and hip is responsible not only for the resting Q angle, but also for the functional Q angle. The functional Q angle observed dynamically during sport-specific movements may be exaggerated beyond the resting Q angle with weighted foot strike, especially in those athletes with a significant degree of foot pronation or functional foot pronation during exercise. Some female athletes exhibit "miserable malalignment" (also called "malicious malalignment") (Fig. 1 ) consisting of femoral anteversion, external tibial torsion, and foot pronation.⁴ The female athletes, with broader hips than male athletes and a significant tendency toward genu valgum, have a larger Q angle then their male counterparts. Add to this anatomical difference the possibility that female athletes are not as well conditioned as male athletes with respect to quadriceps strength, specifically the vastus medialis oblique (VMO), which has a significant tethering effect on the patella to resist lateral motion, and the increased female-to-male ratio becomes more easily understood.

Significantly, the only two anatomic sites that can be altered nonsurgically to diminish the Q angle are the subtalar joint and the pronated foot. It is highly probable that the same difference in the kinetic chain of the lower extremity between men and women that puts women at risk for PFPS also holds the key for reducing overuse injuries to the female knee. By affecting the Q angle at the site of the subtalar joint and the foot, the lower extremity kinetic forces at the knee responsible for PFPS can be altered.

Current appropriate, nonsurgical treatment of the vast majority of athletes with PFPS includes rest, nonsteroidal anti-inflammatory drugs, and physical therapy, with anti-inflammatory modalities leading to an aggressive VMO conditioning program, stretching of the quadriceps and hamstrings, patella stabilization braces, McConnell taping, and biomechanical foot orthoses (BFOs). Bracing and McConnell taping are designed to resist the natural tendency of the patella to center itself laterally within the arc of the Q angle during active quadriceps contraction. BFOs have been used inconsistently in the treatment of PFPS, are considered an expensive form of therapy, and are not prescribed as a first-line treatment modality.⁷ The complete lack of standardization in casting, materials, flexibility, production, and fitting technique makes BFOs difficult to evaluate as a treatment modality. BFOs are prescribed, fitted, and made by podiatrists, orthopedic surgeons, physical therapists, primary care sports medicine physicians, and orthotists in a variety of forms and stiffness, ranging from malleable shoe inserts to rigid plastic orthoses. Frequently, distant laboratories create generic orthoses of rigid polypropylene for a variety of sports medicine specialists and for a variety of athletes. BFO treatment of PFPS is underused because of the perception that BFO treatment is only to be used when excessive food pronation at rest is obvious. This concept must be broadened to take into account the principles of functional pronation with exercise, the functional increase of the Q angle with exercise, and the importance of the subtalar joint in diminishing the stresses that affect the patellofemoral joint. It is apparent that the BFO treatment of PFPS has not been consistently applied, routinely subjected to quality assurance, or properly studied.

The premise of this retrospective clinical investigation is that athletes/patients properly evaluated, diagnosed, and selected for BFO treatment of PFPS can be successfully treated with BFOs alone, if the BFOs are made by an experienced orthotist well trained in casting, fitting, and modification. Proper selection of athletes and consistency in the production of the BFOs should result in uniform success, as evidenced by return to sport and pain-free or pain-tolerable performance in a high percentage of athletes using BFOs alone as a first-line treatment for PFPS.

Wearing well made, comfortable BFOs will increase patient compliance when contrasted with the other forms of treatment for PFPS. Patellar bracing and McConnell taping are very difficult to initiate during the acute pain period associated with PFPS, inasmuch as these treatments tend to intensify the pain because both put direct pressure on the patella. BFO treatment is the only form of therapy that addresses correcting the biomechanical malalignments in the lower extremity kinetic chain.

Methods

All patients included in this retrospective clinical investigation were evaluated by the same sports medicine physician, who is experienced in the specific diagnosis of nontraumatic PFPS and who consistently applied the same criteria for the diagnosis of PFPS during the 36-month period between November 1995 and October 1998. The research of Galanty et al. indicates that physicians who care for teenagers are not uniformly skilled at identifying the causes of anterior knee pain and making the specific diagnosis of PFPS in athletes.¹

BFOs were prescribed if patients met the following criteria for PFPS: 1) no history of acute injury; 2) anterior knee pain significantly affecting athletic, vocational, or avocational performance; 3) pain levels of grade 3 or grade 4 (as outlined by Doug McKeag⁸) in which grade 3 pain occurs before, during, and after exercise and grade 4 pain does not allow the athlete/patient to exercise; 4) a history of knee pain with running or hiking made worse by ascents and descents or a positive "theater sign" (pain upon standing after sitting for a prolonged period); 5) documentation of specific pain to palpation on the medial facet of the patella or a positive "inhibition test" (setting the patella in the femoral groove prevents quadriceps contraction); 6) recognition of the "miserable malalignment" and/or documentation of a large Q angle of over 15 degrees in women and over 10 degrees in men; and 7) determination of significant foot pronation at rest and/or during a treadmill running evaluation to recognize functional foot pronation.

Quadriceps atrophy and knee joint effusion may be present in a small number of patients, but these findings were not considered necessary for the diagnosis of PFPS and, when present, should alert the physician to a more serious knee condition. All patients included in this investigation had PFPS as their only diagnosis. Patients with other knee abnormalities were excluded.

All BFOs used in the investigation were made by the came certified orthotist using the same procedures and materials for orthoses evaluation, casting, fabrication, and fitting. Evaluation of the athlete's gait was performed with careful attention to the alignment of the hindfoot, midfoot, and forefoot during stance phase. In a supine position, a negative impression of the foot was taken in subtalar neutral with forefoot perpendicular to the long axis of the extremity. The longitudinal arch is of a particular height in this position and will be captured in the impression, with special care given to the plantar surface of the foot during molding of the plaster to insure metatarsal arch support. Modifications of the cast include intrinsic posting of the hindfoot and forefoot necessary to attain subtalar neutral and accentuation of the metatarsal arch.

A Nylacork orthosis (APEX Foot Health Industries, Hackensack, NJ) was made from the positive model (see Fig. 3 ). The BFO was formed to fit into the athlete's shoe by shaping the underside to accommodate the instep of the shoe with the shoe's insole removed. The BFO was then fitted to the plantar surface of the athlete's foot for comfort. The BFO during weightbearing should provide for even pressure distribution in the arch, so as to avoid discomfort caused by isolated areas of high pressure. The BFO should also support the foot in subtalar neutral position. A 2-week follow-up visit was scheduled and subsequent follow-ups were arranged until comfort and function were attained. Six months after BFOs were fitted, each patient was sent a questionnaire to evaluate their knee pain caused by PFPS and their response to BFOs as a first-line treatment. The BFO Questionnaire is provided in Table 1 .

Results

All results of this clinical investigation are summarized in Tables 2 and 3 . Of 57 questionnaires sent out to PFPS athletes/patients, 41 were returned, representing a 72% response rate. The results were divided into sex- and age-related subsets of females less than 20 years old (32% of respondents), female patients 20 years and older (39%), male patients less than 20 years old (12%), and male patients 20 years and older (17%). Time to pain reduction and degree of pain reduction were summarized for each age group subset. Of the 41 respondents, all but 3 were still wearing their foot orthoses at 6 months follow-up. The weighted average degree of pain reduction for all subsets was 67%, occurring at an weighted average time of 21.5 days. The younger athletes/patients experienced a greater degree of pain reduction than the older athletes/patients. In determining time to pain reduction, average values for days, weeks, and months were assigned to respondent's answers to question 3. If a respondent stated that he or she had relief in days, then 4 days was used as a weighted average. For relief in weeks, 2 weeks was used as the average, and for months, 3 months was used as the average. Immediate pain relief was registered as 0 days.

Discussion

The results of this clinical investigation indicate that BFOs as a first-line treatment for PFPS for athletes/patients with grade 3 or grade 4 pain level are highly effective in reducing PFPS pain levels in a timely fashion. Generally, athletes/patients experienced significant pain relief within weeks of using the BFOs. With pain reduction, athletes/patients were able to resume specific conditioning exercises to meet the demands of their sport or activity. In addition, once pain was controlled, athletes/patients were then able to start aggressive VMO muscle strengthening programs to provide dynamic patellar stabilization to further reduce the pain of PFPS. Figure 4 shows the significant effect BFOs have on the lower extremity kinetic chain, both at rest and with exercise. A reduction of the functional Q angle by a few degrees has a significant impact on PFPS, realigning the patella in the femoral groove and reducing friction between the chondral surfaces of the patella and the femur.

The concomitant use of patellar stabilization bracing or McConnell taping has proved to be unnecessary in the patient population presented in this investigation. Surgical intervention or even orthopedic referral has not been used during the 3-year period of this investigation for those athletes/patients with PFPS as their only diagnosis. Surgery for PFPS is unsatisfactory and has infrequently created catastrophic secondary problems.⁹ The surgical treatments of lateral retinacular release, patellar shaving, plical excisions, and tibial tubercle transplants have diminished in frequency. With proper nonsurgical treatment and the evolution in our understanding of the natural course of this self-limited overuse condition, any surgical intervention should be considered archaic for the treatment of PFPS.

The older subset of patients with PFPS frequently involves recreational athletes and active nonathletes. BFOs provide this group with pain relief, increased function, and a treatment form that meets with great compliance and comfort.

Because this investigation involved a combined family practice and sports medicine practice, there is a considerable age range and a variety of athletes/patients participating in activities that are not exclusively associated with adolescents. Therefore, the results are presented in subsets of female and male age groups of under 20 years old and 20 years and older. The effectiveness of BFOs to reduce the pain of PFPS in properly selected and evaluated athletes/patients is evident throughout all subsets. Although the number of subjects involved in this clinical investigation is small, there are some general statements about the subset differences that seem accurate:

1) Younger athletes respond more quickly than older athletes.
2) Younger athletes have a greater degree of pain relief than older athletes.
3) The subset of older men took longer to respond and had less pain reduction than the other subsets.
4) Because women have a greater degree of lower extremity malalignment than men, it is apparent that their numbers are greater for experiencing PFPS.
5) Young men may experience PFPS earlier in life than young women, but the small numbers preclude drawing anything but an inference. The young men in this study responded very quickly to treatment with BFOs and had a high degree of pain relief.
6) Young women also respond quickly with BFO treatment and with the highest degree of pain relief of any subset.

BFOs have proven cost-effective within the medical practice conducting this clinical investigation as a first-line treatment for PFPS with pain grades of 3 and 4. The costs within the study population averaged as follows:

  Sports medicine evaluation = $77.00
Orthotist fee = $260.00
Medical follow-up = $45.00
Total = $382.00

If the same athlete/patient was referred to an orthopedic surgeon and physical therapist, the charges would be as follows:

  Sports medicine evaluation = $77.00
Orthopedic evaluation = $87.00
Four-view knee radiographs = $95.00
Physical therapy evaluation = $90.00
Four therapy sessions = $300.00
Patellar brace = $58.00
Total = $707.00

Certainly the majority of PFPS athletes/patients are pain grade 1 (pain after exercise) or pain grade 2 (pain before and after but not during exercise). These athletes/patients can be treated quite simply with activity modification, ice and heat, anti-inflammatory medication, hamstring and quadriceps stretching, and a home program of short-arc, closed-chain VMO exercises.

Conclusion

In summary, this clinical investigation strongly suggests that BFOs can be used as a highly effective first-line treatment of PFPS with pain grades of 3 and4 in a family practice/primary care sports medicine setting. Once the biomechanical malalignments of the lower extremity kinetic chain are addressed with BFOs and pain levels diminish, then VMO exercises and sport-specific training can begin, with further reduction of pain and improved dynamic patellar muscular stabilization. It is the feeling of these investigators that the success of the BFO first-line treatment of athletes/patients with PFPS will be directly proportional to the accuracy of the initial physician evaluation and the quality and consistency of the BFOs made available. The small numbers in this clinical investigation are compelling, but additional study is needed in this area by larger sports medicine centers with a greater volume of athletes/patients. The information presented here by a small, rural sports medicine clinic calls for a larger center to perform a prospective double-blinded study complete with biomechanical video analysis to elucidate the role of BFOs as a first-line treatment for PFPS.

Copyright ©2000 American Academy of Orthotists and Prosthetists.

Doug Pitman, MD, is board-certified with the American Board of Family Practice and holds a Certificate of Added Qualification in Sports Medicine. He is a member of the American Academy of Family Physicians and the American Medical Society for Sports Medicine, Columbia Falls, MT.

Doug Jack, CPO, is a certified prosthetist and orthotist with Northern Care Prosthetics and Orthotics, Kalispell, MT.

References:

1. Galanty HL, et al. Anterior knee pain in adolescents, Clin J Sports Med. 1994;3:176-181.
2. Rice SG. An injury surveillance system. Sports Med Dig. 1991;8:1-2.
3. Rice SG. Epidemiology and mechanisms of sports injuries. In: Teitz CT, ed. Scientific Foundations of Sports Medicine. Philadelphia: Decker; 1989:3-23.
4. Arendt EA. Orthopedic issues for active and athletic women. Clin Sports Med. 1994;2:488-493.
5. Fadale PD, Hulstyn MJ. Common athletic knee injuries. Clin Sports Med. 1997;3:493-497.
6. Nimon G, Murray DW, Sandow MJ, Goodfellow JW. The natural history of anterior knee pain: A 14 to 20 year follow-up of nonoperative management. Paper presented at: Annual Meeting of the American Academy of Orthopaedic Surgeons; February 24, 1996; Atlanta, Georgia.
7. Post WR. Patello femoral pain: Let the physical exam define the treatment. Physician Sports Med. 1998;26:68-78.
8. McKeag D. Sports Medicine--Overuse Injuries [videotape]. The American Academy of Family Physicians CME Video Series; 1989.
9. DeLee JC, Drez D Jr, eds. Orthopedic Sports Medicine Principles and Practice. Philadelphia: W.B. Saunders; 1994:1196-1197.