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the TP tendon transfer have been reported, controversy persists on the risk of acquired flat foot deformity following
this procedure. In addition, no consensus exists regarding
whether a restoration of muscle strength acting on the ankle
joint from transfer adequately restores function for daily
and sports activities.
The purpose of this study was to report objective and
validated functional outcome measures over intermediateterm follow-up after TP tendon transfer for foot drop secondary to peroneal nerve palsy, and to evaluate whether
postoperative flat foot deformity developed.

Methods
Between June 2008 and April 2013, 17 patients underwent
TP tendon transfer for foot drop secondary to peroneal nerve
palsy and were observed for more than 3 years postoperatively. A control group of 17 adults without a history of ankle
injury were enrolled and matched according to the age, sex,
operated side. The indications for surgery were patients who
complained of gait disturbance caused by foot drop for more
than 8 months with no functional improvement with severe
peroneal nerve palsy without definite evidence for regeneration identified with periodic electromyography (EMG) and
nerve conduction velocity studies. Patients with footdrop
caused by proximal neurologic pathology such as brain
injury, lumbar radiculopathy, or sciatic nerve palsy were
excluded. Patients with spasticity or fixed foot deformity
that could not be placed in a plantigrade position were also
excluded. All patients presented with no significant bony
abnormality on radiographic evaluations and demonstrated
adequate triceps surae and TP muscle power (grade 4 or
higher, good). All patients had undergone at least 6 months
of conservative treatment prior to surgery, which included an
ankle-foot orthosis with a plantarflexion stop hinge and
muscle strengthening rehabilitation. All patients had mental
and physical abilities to participate in the postoperative rehabilitation period.
At the time of surgery, mean patient age was 35.8 years
(range, 18-59 years), and mean symptom duration was 11.4
months (range, 8-15 months). The patient sample included
10 men (58.8%) and 7 women (41.2%), with 9 having the
right foot involved (52.9%) and 8, the left foot (47.1%). The
mean length of follow-up was 65.6 months (range, 37-98
months). Eight patients were noted to have a supination
deformity during the swing phase of gait. With respect to
the cause of peroneal nerve injury, there were 6 patients
with iatrogenic nerve injury (TKA, knee arthroscopic procedure, injuries related to splint or cast immobilization), 4
patients with proximal tibiofibular fracture accompanying
compartment syndrome, 3 patients with history of peroneal
nerve exploration and surgical repair following acute laceration or penetrating injury, 2 patients with direct blow
injury, and 1 patient with fibular head fracture; 1 patient

Foot & Ankle International 38(6)
was considered idiopathic. Operative procedures and physical examination included assessment of joint mobility,
strength testing of all relevant musculotendinous units, and
sensory evaluation performed by one senior surgeon. The
study protocol and investigation were conducted with
Institutional Review Board approval, and written informed
consent was obtained.

Surgical Technique and Postoperative
Rehabilitation
First, in cases with passive dorsiflexion less than 5 degrees
with the knee extended, Achilles tendon lengthening using
triple hemiresection technique was performed to obtain
adequate passive dorsiflexion of 15 degrees or greater. In
the present study, 8 of the 17 patients underwent Achilles
tendon lengthening. We used a 4-incision technique for tibialis posterior tendon transfer as described by Hsu and
Hoffer3 for all patients. The TP tendon was delivered anteriorly through the interosseous membrane, and passed
through a subcutaneous tunnel over the extensor retinaculum. The insertion point of the transferred TP tendon was
selected on the basis of peroneal strength on preoperative
examination. In 8 patients with the presence of concomitant
peroneal muscle weakness (grade 3 and less), the TP tendon
was transferred to the lateral cuneiform. Otherwise, the TP
tendon was transferred to the middle cuneiform for 9
patients with relatively strong peroneal muscles (grade 4
and 5). After determination of appropriate tension to maintain the ankle joint in 10-degree dorsiflexion position, the
TP tendon stump was inserted into a bone tunnel in the
middle or lateral cuneiform, using a bioabsorbable interference screw for tendon-bone fixation. Finally, the tendon end
inserted into bone was sutured to the periosteum to enhance
a stable attachment.
A short leg splint and non-weight bearing ambulation
with crutches were maintained for 2 weeks. A short leg
walking cast was used for 6 weeks postoperatively.
Thereafter, active and gentle passive range of motion
(ROM) exercises, and partial-weight bearing ambulation
were encouraged. Full-weight bearing was permitted from 8
weeks postoperatively, followed by physical therapy including muscle strengthening, massage, and stretching for a
minimum of 3 times a week for 2 months or longer, gait
training (walk in a heel-to-toe pattern), and proprioception
training. The use of a night splint was recommended for 3
months to prevent recurrent equinus deformity. All patients
were instructed to avoid running or jumping exercises for 6
months.

Clinical and Radiologic Assessment
Functional outcome tools included the American Orthopaedic
Foot & Ankle Society (AOFAS) ankle-hindfoot scores, Foot

Table of Contents for the Digital Edition of Foot & Ankle International - June 2017