Prospective Trial of Minimally Invasive Surgery Versus Standard Surgery for Correction of Hallux Valgus

Randomized prospective trial of minimally invasive surgery versus standard surgery for
correction of hallux valgus.

Introduction

It is estimated that more than 200,000 hallux valgus surgeries are performed each year in
the United States. [1] More than 100 procedures have been described for correction of hallux
valgus.[2] Considerable controversy remains over the best technique.

Recently, a number of minimally invasive techniques for correction of hallux valgus have
been described. [3, 5, 6]. These minimally invasive techniques emphasize less traumatic
surgical exposure and more limited dissection of the soft tissues. It has been proposed that
minimally invasive procedures lead to less pain, decreased swelling, shorter recovery times
and more rapid return to full weightbearing activities. Not all reports have been positive,
and some authors report an increased number of complications, including loss of correction
and malposition of the bones [7].

Minimally invasive treatment of hallux valgus is becoming increasingly common in podiatric
and orthopedic clinical practice, due to the theoretical advantages of more rapid recovery,
more rapid return to full activities, and decreased pain. These techniques have the
potential advantage of providing better clinical outcomes and having lower cost.

An increasing number of research publications on this topic have appeared in recent years,
which reflects both growing interest and development in this field amongst foot and ankle
surgeons. However, despite the increasing interest, there are no high-quality studies of
these procedures available. In a 2011 systematic review [8], 24 publications describing the
outcomes of minimally invasive hallux valgus surgery were identified and analyzed. All the
studies were level IV quality (case series, with the exception of two that were level III (a
retrospective comparative studies). No randomized prospective controlled studies have been
published, and validated disease-specific outcomes measures are seldom used [9].

No high quality trials of any minimally invasive techniques have been published, and as a
result, basic questions still remain unanswered: Do minimally invasive procedures have fewer
complications than standard procedures? Are minimally invasive procedures associated with
superior patient-based outcomes? Are the radiographic outcomes of minimally invasive
techniques equivalent? Randomized, prospective clinical trials are required, utilizing
validated outcomes measures.

Study Objectives

To compare the patient-based outcomes and radiographic outcomes of minimally invasive
surgery versus standard surgery for correction of hallux valgus.

Primary Outcomes Measure

The primary outcomes measure is the Manchester-Oxford Foot Questionnaire Score (MOXFQ).
Manchester-Oxford Foot Questionnaire' (MOXFQ), a 16 item patient-reported questionnaire
consisting of three domains/scales: 'Walking/standing' (seven items), 'Pain' (five items)
and 'Social interaction' (four items). The MOXFQ is a validated disease-specific outcomes
scale for foot and ankle surgery which has been shown to be responsive and reliable. In
observational studies, minimal clinically important difference (MCID) for the various
domains of the MOXFQ were 16, 12, and 24 for the MOXFQ Walking/standing, Pain, and Social
Interaction domains, respectively. The MOXFQ has demonstrated good responsiveness when
compared with the AOFAS forefoot score. Statistical analysis of the data will show if the
null hypothesis that there are no statistically significant differences between groups with
respect to the postoperative MOXFQ scores at 12 weeks, 1 year, 2 years and 3 years is
rejected.

Secondary outcome measures are preoperative to postoperative change in hallux valgus angle
(HVA). Radiographic outcomes parameters will be measured using weight-bearing radiographs to
analyze preoperative and postoperative hallux valgus angle, and the correction or
normalization thereof. (Degrees of correction = preoperative HVA - 12 week postoperative
HVA.)

Statistical analysis of the data will show if the null hypothesis that there are will be no
statistically significant differences between groups with respect to the degree of
correction of the hallux valgus angle is rejected.

Study Design

Type

Non-inferiority treatment study, open-label, randomized, prospective, controlled, parallel
experimental design.

Location

Study-related patient visits will take place in the office of the principal investigator,
Dr. Henry DeGroot, white 544, Newton Wellesley Hospital MOB Surgery will take place in the
operating rooms at the Newton Wellesley Hospital. Post operative evaluations will take place
in the office of the principal investigator and in the Newton Wellesley Hospital cast room.
Preoperative and postoperative x-rays will take place in the radiology department of the
Newton Wellesley Hospital.

Duration

Subjects will be enrolled until sufficient numbers have been achieved for the two groups,
which is estimated to require 36 months. The time of active participation for each subject
will be 12 weeks.

The period of long-term follow-up for each subject will be 36 months, beginning from the
date of surgery.

Research Plan

Study Intervention

The study will compare two surgical techniques for correction of hallux valgus, which are
detailed below. Other than the intraoperative surgical technique, the preoperative and
postoperative treatment will be identical for all subjects. Radiographic examinations of the
feet (x-rays) will be made preoperatively and at two weeks postoperative and 12 weeks
postoperative, as per the usual and customary practice of the principal investigator.

The conventional surgical technique is a Chevron-type distal metatarsal osteotomy, which is
performed through a dorsomedial incision approximately 7 cm long. And osteotomy of the
distal portion of the first metatarsal is made. The capital or distal fragment of the
metatarsal is mobilized and displaced laterally an adequate amount to correct the hallux
valgus deformity. The capital or distal fragment is stabilized in corrected position with
screws. The internal fixation screws used in the conventional surgical technique do not
require removal. Through the same incision, the contracted soft tissues on the lateral
aspect of the metatarsophalangeal joint are released. Per the patient's request and consent,
other planned bony or soft tissue pathology of the lesser toes that requires surgical
correction (eg, hammer toes) will be treated in the same surgical session using standard
techniques.

The minimally invasive surgical technique is a transverse subcapital distal metatarsal
osteotomy, which is performed through a direct medial incision approximately 1 cm long. The
osteotomy of the distal portion of the first metatarsal is made using fluoroscopic image
guidance. The capital or distal fragment of the metatarsal is mobilized and displaced
laterally an adequate amount to correct the hallux valgus deformity. A 2.0 mm Kirschner wire
is placed percutaneously in a position medial to the proximal phalanx, and advanced
proximally using fluoroscopic guidance until the proximal end of the wire is located in a
stable position within the medullary cavity of the first metatarsal (see figures) .The
distal end of the Kirschner wire is left outside the skin where it is cut to length and
covered. The Kirschner wire is removed after six weeks. The soft tissues on the lateral
aspect of the joint are not released. Per the patient's request and consent, other planned
bony or soft tissue pathology of the lesser toes that requires surgical correction (e.g.,
hammer toes) will be treated in the same surgical session using standard techniques.

Postoperative Care -

- First post operative is: one week postoperative

- Second postoperative visit: two weeks postoperative

- Third postoperative visit: 6 weeks postoperative

- Last postoperative visit: 12 weeks postoperative

Period of Long Term Follow Up

- 1 year follow up - completion of questionnaire. This can be completed by email, regular
mail, or in person, depending on the patients preference.

- 2 year follow up - completion of questionnaire. This can be completed by email, regular
mail, or in person, depending on the patients preference.

- 3 year follow up - completion of questionnaire. This can be completed by email, regular
mail, or in person, depending on the patients preference.

Study Costs

All costs associated with the usual and customary perioperative, operative, and
postoperative care of the patients will be billed to the patient's medical insurance.
Subjects will incur no costs that are solely for the purposes of research. Any study costs
for the purposes of the research study will be supported by the principal investigator.
These costs are not expected to be large. The main cost will be the time needed to inform
the patient of the study process, obtain consent, gather the data and store it. The PI feels
that unsupported research is a feasible and preferable alternative to industry funded
studies, which have been shown to be much more likely to have significant bias.

Randomization and Blinding

After a study subject has been enrolled, they will be randomized to one of two treatment
groups. All subjects will be randomized, 1:1 either to the conventional surgery group (group
A) or the minimally invasive surgery (group B). Randomization will take place after
enrollment via selection of a one of a multitude of envelopes containing a random number. A
block randomization technique will be used with a block size of eight. Each random number
will have been preassigned to either group A or group B.

The envelope containing the patient's group assignment will be opened in the operating room
immediately prior to commencing the surgery. Due to the nature of the surgery, neither the
investigators nor the patients can be effectively blinded to the results of the group
assignment. The patients will be made aware of the group assignment after the surgery.

Primary outcomes measure and secondary outcomes measure

The primary outcomes measure is the Manchester-Oxford Foot Questionnaire Score (MOXFQ).
Manchester-Oxford Foot Questionnaire' (MOXFQ), a 16 item patient-reported questionnaire.

Secondary outcome measures are preoperative to postoperative change in hallux valgus angle
(HVA).

Data Collection and Statistical Analysis

The study documents will be labeled with the patients random number, and the data will be
stored using only this unique random number identifier. The patient's name and group
assignment will not appear on any study document. Data related to the MOXFQ will be recorded
on a visit summary document bearing only the patient's random number, and later entered into
a computerized spreadsheet using the patient's random number as a unique identifier. The
patients personal data will not be stored along with the aggregate data. Data will be kept
in a password secured computer in the office of the PI.

Power Analysis

Power analysis was performed using G*Power 3.0.10 (Department of Experimental Psychology
Heinrich-Heine-University 40225 Düsseldorf Germany -
http://www.psycho.uni-duesseldorf.de/aap/projects/gpower/). Power was calculated for the
differences of two independent means (two groups). Given an estimated population effect size
(d) of 0.65, a probability of alpha error (significance) of 0.05, and a required power (1-
beta) of 0.80, the total required sample size would be 78 (two groups of 39). The two-tailed
test is used because we cannot assume that the differences in the treatment effect in the
two groups will be in one direction only, that is, we have assumed that the treatment effect
may either be smaller or larger in the conventional surgery group than in the minimally
invasive surgery group. Our goal is to enroll 80 patients in the trial. For independent
samples, the Mann-Whitney test will be used to examine the difference between the two
groups.

Study Endpoints

The study endpoint will occur when a sufficient number of patients have completed the 36
month long term follow-up process. Our aim is to enroll a minimum of 60 and a maximum of 100
patients. Once the last patient enrolled has completed the 36 month survey instrument, the
data collection phase of the study will be completed.

Inclusion Criteria:

1. Age > 18 years old

2. Patients with mild to moderate hallux valgus which has been unresponsive to
nonoperative measures. Mild to moderate hallux valgus deformity is defined by
weightbearing xray-findings of a hallux valgus angle of greater than normal (< 15°)
and less than 39°, and a intermetatarsal angle less than 18°.

3. Patients who are willing to be randomized to either of the surgical procedures.

4. Patients who are able to understand and sign the consent form

5. Patients who are able to understand and complete the study questionnaires

6. Females with no documented evidence of current pregnancy, and willingness to take the
necessary precautions to prevent pregnancy for the duration of the active
participation period (12 weeks).

Exclusion Criteria:

1. Patients who have had previous bunion surgery on the affected foot

2. Patients who have symptomatic arthritis of the metatarsophalangeal joint (hallux
rigidus).

3. History of systemic inflammatory condition or infection of the great toe or nearby
soft tissues

4. Diabetic or neuropathic Charcot arthropathy

5. Significant vascular insufficiency

6. Factors which unacceptably increase the risk of surgical complications