The CurePPaC Study - Analysing Non-surgical Treatment Strategies to Cure Pes Planovalgus Associated Complaints

Pes planovalgus, also called flat foot, is a common foot deformity characterized by a flattening of the foot's longitudinal arch and is accompanied by a dysfunction of the posterior tibial tendon ("posterior tibial tendon dysfunction" or "PTTD"). Early stages of this pathology are thought to be treated with non-surgical therapy options like foot orthoses (relief of tendon stress by mechanical unloading of the arch), strengthening exercises or basic physiotherapeutic measures. Recent literature clearly states the urgent need for high quality studies to evaluate the proposed non-surgical treatments (Bowring 2009, 2010). There is only one high quality study available that shows benefits of orthoses therapy and exercise (Kulig 2009). No study to date evaluated functional changes pre-post in dynamic movement pattern like gait or stair climbing. The widespread use of several non-surgical treatment strategies lead to extensive financial expenses of the health care system. An optimized therapeutic strategy could eventually lead to more efficient health care investments. The presented proposal addresses this latest knowledge and aims to analyse non-surgical treatment strategies to Cure Pes Planovalgus associated Complaints (CurePPaC) in the CurePPaC Study.

Introduction: Pes planovalgus or flatfoot-associated complaints are frequent symptoms, which are thought to be caused by the foot deformity itself. Concurrently, the multifactorial weakness of the M. tibialis posterior and its tendon (trauma, systemic disease, chronic tendon degeneration by overuse) can lead to a flattening of the medial longitudinal arch of the foot. Affected patients suffer from functional impairment and pain. Less severe cases are eligible for non-surgical treatment. Foot orthoses are considered to be the first line approach. Furthermore strengthening of the arch and ankle stabilizing muscles are thought to contribute to an active compensation of the deformity. There is only limited evidence concerning the numerous therapy approaches since high quality studies are missing. One excellent report (Kulig et al. 2009) shows clear benefits by the use of foot orthoses and eccentric strengthening exercises. Beside the fact that evidence-based guidelines for therapy have yet to be developed, no data is available showing functional benefits that accompany the therapy process. This would give further insight into mechanisms behind non-surgical management strategies and how patients benefit functionally from therapy. Purpose: The purpose of this randomized longitudinal intervention study is the evaluation of the therapeutic benefit of three different non-surgical treatment regimens (foot orthoses only FOO, foot orthoses and eccentric exercise FOE, foot orthoses sham treatment FOS) in patients with Pes planovalgus and accompanying complaints. Furthermore the analysis of possible functional changes in gait mechanics (kinematic and kinetic view) and neuromuscular control (electromyographic analysis) will contribute to a superior understanding of functional changes that accompany non-operative management. The purpose of the study is to optimize non-surgical management in patients suffering from Pes planovalgus associated pain leading to an efficient use of health care system's financial resources. Methods: 60 patients with Pes planovalgus associated complaints (clinical diagnosis with plain weight bearing radiographs), M. tibialis posterior dysfunction) are included in the study. Functional impairment is evaluated pre and post intervention by the Foot-Function-Index (FFI, German version). Anthropometric data recording is followed by preparation of subject's foot anatomical landmarks with retroreflective markers and superficially detectable muscles of the ankle joint complex are prepared with surface electromyography (SEMG) electrodes. The 3D kinematic data allows inter alia the calculation of segmental angels of the lower extremity and measurement of navicular drop. The neuromuscular activity is analysed in the time (on-off pattern) and amplitude domain (gait cycle specific phases). Procedure: Potential participants are recruited via the Outpatient Clinic of the Department of Orthopaedic Surgery of the Inselspital, University Hospital, Bern. After initial screening, subjects are randomized to one of three intervention groups (foot orthoses only FOO, foot orthoses and eccentric exercise FOE, foot orthoses sham treatment FOS). FOO-subjects wear custom-made foot orthoses only. FOE-subjects wear individually accustomed foot orthoses and they will perform a combined monitored and home training program to progressively strengthen the M. tibialis posterior and accompanying ankle stabilizing muscles with eccentric exercises. FOS-subjects wear custom-made sham foot orthoses without the functional elements of the treatment orthoses (longitudinal arch support, ankle stabilizer, bowl-shaped heel for rearfoot stability). Subjects are measured pre and post intervention (12 weeks). Measurements include the primary outcome measure Foot-Function-Index (FFI, German version: total score) followed by basic anthropometric measures. Subject preparation allows then the measurement of 10 trials on a walkway and on stairs with embedded force plates in barefoot condition. An average step cycle out of 10 trials is calculated and biomechanical outcome measures are extracted. A re-test allows the calculation of intervention effects by one-factor ANOVA (group: treatment FOO vs. FOE vs. FOS) for repeated measures.

Eligibility Criteria:
Inclusion Criteria:

* Age: 18-60
* Current complaint of foot and ankle pain that lasted for 3 months or more
* Flexible Pes planovalgus deformity in the clinical assessment
* Posterior tibial tendon dysfunction (PTTD) of stage I and II (Johnson \& Strom 1989)
* Pes planovalgus foot deformity with longitudinal arch flattening verified by radiograph (Younger 2005): Lateral view: lateral talo-first metatarsal angle ≠ 0° (break of axis): angle \>10° according to Younger (2005); 60Anteroposterior view: anteroposterior talo-first metatarsal angle ≠ 0° (break of axis): angle \>10° according to Younger (2005)
* "too-many toes"-sign from rear frontal view with an abducted forefoot (Johnson \& Strom 1989, Kulig 2009b)
* Eligibility for non-surgical treatment
* No indication / not yet an indication for surgical treatment of foot deformity

Exclusion Criteria:

* Rigid foot deformity
* Posterior tibial tendon dysfunction (PTTD) of stage III and IV according to Johnson \& Strom 1989 (=\>rigid foot deformity)
* Cardio-, neuro-, or peripheral vascular pathology, musculoskeletal pathology, acute infection or alcohol addiction limiting participation in study protocol
* Acute use of local or systemic analgesics
* Acute physical therapy, training therapy or physiotherapy
* Acute overuse or traumatic injury to the lower leg (excluding Pes planovalgus associated pathology)
* Prior surgery to the lower limb