Follow-up and Outcome of Operative Treatment With Decompressive Release Of The Peroneal Nerve

Time to recovery

KEY SECONDARY ENDPOINT Time to recovery is defined as: the time necessary to cover the minimal age- and sex-specific normal distance in meters during the 6-minute walking test (6MWT) AND the time necessary for foot drop recovery to an MRC-score ≥ 4 for ankle dorsiflexion. The MRC-score is a clinical assessment of muscle strength. MRC-ranges from 0 to 5 with zero indicating no movement at all and 5 indicating normal muscle strength. The minimal age- and sex-specific normal 6-minute walking distance (6MWD) is defined as 82% of the applied reference equations for prediction of the 6MWD. The reference value that will be used is 6MWDpred(m) = 868.8 - (ageyears x 2.99) - (gender x 74.7). The value for gender is 0 in male subjects and 1 in female subjects.

Time frame: 6 weeks, 3 months, 6 months, 9 months and 18 months (after randomization)

Ankle dorsiflexion strength as measured by the Medical Research Council score (MRC-score).

Medical Research Council (MRC)-score as clinical assessment of muscle strength. MRC-score ranges from 0 to 5. 0: no movement 1. contraction of muscle, but no movement 2. movement, but not against gravity 3. movement against gravity, but not against resistance 4. movement against resistance 5. normal strength

Time frame: 10 days (surgery), 6 weeks, 3 months, 6 months, 9 months and 18 months (after randomization))

Ankle dorsiflexion strength as measured by isometric dynamometry.

Recovery of ankle dorsiflexion strength is essential in patients with foot drop. The use of dynamometry allows to document ankle dorsiflexion strength in an objective manner. Patients are asked to lay in supine position, with the knees extended. The test pad of the dynamometer is placed on the dorsal head of the first metatarsal bone. The patient is instructed to perform ankle dorsiflexion with maximal muscle strength. The best of three attempts is registered. Ankle dorsiflexion is measured and reported in both ankles (in kilograms). The ankle dorsiflexion strength ratio, defined as the ratio of ankle dorsiflexion strength in the affected ankle over ankle dorsiflexion strength in the healthy ankle will be calculated and reported

Time frame: 10 days (surgery), 6 weeks, 3 months, 6 months, 9 months and 18 months (after randomization))

Complications and neurologic deficits: Motor changes as assessed by the Medical Research Council Score (MRC-score) for hallux extension

Medical Research Council (MRC)-score as clinical assessment of muscle strength. MRC-score ranges from 0 to 5. 0: no movement 1. contraction of muscle, but no movement 2. movement, but not against gravity 3. movement against gravity, but not against resistance 4. movement against resistance 5. normal strength

Time frame: 10 days (surgery), 6 weeks, 3 months, 6 months, 9 months and 18 months (after randomization))

Complications and neurologic deficits: Sensory changes

In a large retrospective patient series on peroneal nerve decompression after weight loss, Broekx et al. (2018) examined the recovery of sensory deficits. Symptoms qualified as sensory included the presence of hypoesthesia and/or paresthesia. They used the following system to assess sensory symptoms: 1. Complete recovery: the absence of any sensory symptoms 2. Partial recovery: patients with a minimum of sensory symptoms 3. No recovery: patients with no improvement

Time frame: 10 days (surgery), 6 weeks, 3 months, 6 months, 9 months and 18 months (after randomization))

Gait assessment: Difference in distance covered in meters during the six-minute walk test

The distance covered during the six-minute walk test (6MWT) is validated and clinically used in gait analysis. 6MWT: patients are instructed to walk as far as possible within six minutes (strokes of 30 meters of more). The minimal age- and sex-specific normal 6MWD is defined as 82% of the applied reference equations for prediction of the 6MWD. The reference value that will be used is 6MWDpred(m) = 868.8 - (ageyears x 2.99) - (gender x 74.7). The value for gender is 0 in male subjects and 1 in female subjects.

Time frame: 6 weeks, 3 months, 6 months and 18 months (after randomization)

Gait assessment: Stanmore questionnaire

The Stanmore questionnaire has been used in the literature to assess functional outcome in patients with foot drop due to peroneal nerve injury. Seven sections (pain, need for orthosis, normal shoes, functional outcome, muscle power, degree of active dorsiflexion and foot posture) add up to a sum score of 100 points.

Time frame: 6 weeks, 3 months, 6 months, 9 months and 18 months (after randomization)

Gait assessment: Functional ambulation categories

Functional ambulation categories (FAC) is a useful scale to assess gait in patients with foot drop. It is a six point scale, that is used in stroke literature and can help determine how much assistance a patient requires. FAC 0 reflects a nonfunctional state and FAC 5 equals a normal gait pattern.

Time frame: 6 weeks, 3 months, 6 months, 9 months and 18 months (after randomization)

Gait assessment: Gait speed as measured by the 10-meter walk test

Walking speed is an important aspect of gait and is often used as an objective measure of functional mobility. The 10-meter walk test is a commonly used and validated tool to assess gait speed.

Time frame: 6 weeks, 3 months, 6 months, 9 months and 18 months (after randomization)

Health economic assessment: Work Productivity and Activity Impairment Questionnaire (WPAI)

Health economic aspects of foot drop will be evaluated through the Work Productivity and Activity Impairment Questionnaire (WPAI). The WPAI is widely used and validated in multiple languages. The WPAI questionnaire consists of 6 questions with regard to professional activity during the past 7 days.

Time frame: 6 weeks and 6 months after randomization

Complications and neurologic deficits: Surgical complications

A list of possible complications is made available to all participating centers. Unforeseen complications will be recorded as free-text.

Time frame: 10 days, 6 weeks and 18 months after surgery

Electrodiagnostics: evolution of conduction block at the level of the fibular head

All patients will have repeated electrodiagnostic examinations. The evolution of the conduction block at the level of the fibular head will be documented in the eCRF.

Time frame: 3 months and 9 months after randomization.

Patient-reported outcome measurements regarding health-related quality of life: 5 Level Euro Quality of Life 5 Dimensions (EQ5D-5L)

The EQ-5D 5L is a generic measure of health-related quality of life developed by the EuroQol Group. It is a validated measurement of quality of life widely used in different pathologies. The questionnaire is made up of two parts. The first part is descriptive and uses five different dimensions to score quality of life. These five dimensions are mobility, self-care, activities of the daily life, pain/discomfort and anxiety/depression. There are five different answer possibilities within each dimension, i.e. "no problem", "slight problem", "moderate problem", "severe problem" and "unable to". This renders 3125 different answer possibilities. The second part uses a visual analogue scale (VAS) to score the current health status of the patient, ranging from zero to one hundred. Zero corresponds to death and one hundred corresponds to a (subjective) perfect health status.

Time frame: 10 days (surgery), 6 weeks, 3 months, 6 months, 9 months and 18 months (after randomization)

Health economic assessment: Return to work

Health economic aspects will also be evaluated through the assessment of return to work. We expect subgroups of patients with foot drop to be unable to work. Once the foot drop has improved (or fully recovered), we expect patients to be able to return to work and to not experience any more related problems (after their initial recovery). In this trial population foot drop does in general not represent a chronic condition with periods of relapse. Either the foot drop recovers enough to be able to work again, or the foot drop does not sufficiently recover to resume previous professional activities. Taking this into account, return to work seems to represent a very important measure. Patients will be asked about return to work at the study visit six weeks after randomization. To avoid recall bias, patients will be asked in advance to record the date of return to work. During baseline assessments, subjects will be questioned if they are incapacitated to work due to the foot drop and the

Time frame: 6 weeks

Gait assessment: The proportion of patients in both groups who reach minimal normal age- and sex-specific reference values for distance covered in meters during the six-minute walk test

The distance covered during the six-minute walk test (6MWT) is validated and clinically used in gait analysis. 6MWT: patients are instructed to walk as far as possible within six minutes (strokes of 30 meters of more). The minimal age- and sex-specific normal 6MWD is defined as 82% of the applied reference equations for prediction of the 6MWD. The reference value that will be used is 6MWDpred(m) = 868.8 - (ageyears x 2.99) - (gender x 74.7). The value for gender is 0 in male subjects and 1 in female subjects.

Time frame: 9 months after randomization

Complications and neurologic deficits: Motor changes as assessed by the Medical Research Council Score (MRC-score) for ankle eversion

Medical Research Council (MRC)-score as clinical assessment of muscle strength. MRC-score ranges from 0 to 5. 0: no movement 1. contraction of muscle, but no movement 2. movement, but not against gravity 3. movement against gravity, but not against resistance 4. movement against resistance 5. normal strength

Time frame: 10 days (surgery), 6 weeks, 3 months, 6 months, 9 months and 18 months (after randomization)