This was a retrospective study. The study protocol was approved by the institutional review board of Cangzhou Hospital of Integrated TCM-WM and all patients provided the written informed consent.
The inclusion criteria were age >18 years; stage 3 post-traumatic ankle arthritis classified as Takakura-Tanaka classification, ankle pain and swelling lasting >3 months and failure of conservative treatment; absence of past any surgical procedure around the ankle; complete pre- and postoperative data and imaging examinations, and the follow-up of at least 24 months.
The exclusion criteria were recent infection around the ankle; history of ankle fracture; other serious deformities or diseases of the foot and ankle, such as clubfoot or diabetic foot; incomplete medical record data or lost to follow-up or follow-up period <24 months. Additionally, surgery is contraindicated for those with congenital collagen deficiency; bodyweight >120 kg; severe heart disease; lesions affecting liver and kidney function; severe diabetes; central nervous system diseases; or others.
The above criteria identified 73 consecutive patients who underwent either ankle distraction arthroplasty (n=32) or supramalleolar osteotomy (n=41) for treatment of Takakura-Tanaka stage 3 post-traumatic ankle arthritis after failure of conservative treatment from January 2015 to December 2018.
Among ankle distraction arthroplasty group, there were 19 men and 13 women, with an average age of 54.7±12.8 years; left ankle was affected in 14 and right in 18 patients; 21 had a clear history of ankle trauma and 11 with unknown etiology. Among supramalleolar osteotomy group, 27 were men and 14 were women, with an average of 56.4±11.7 years; left ankle was affected in 17 and right in 24 patients; 29 had a clear history of ankle trauma and 12 with unknown etiology.
Preoperative examination
Preoperative evaluation of all patients included a detailed history ankle arthritis, presence of comorbidities, physical examination, and imaging examination, based on which the ankle anteroposterior position, tibial anterior surface angle (TAS), talar tilt angle (TT) and tibial lateral surface angle (TLS) were measured. The calcaneal axial X-ray was taken to assess the force line of the lower limb and evaluate the presence of varus or valgus of the calcaneus and talus; CT was performed to evaluate the condition of the subtalar and tibiotalar joints; MRI was performed to evaluate the cartilage condition of the ankle, presence or absence of talar necrosis, condition of the surrounding soft tissue, presence or absence of edema of the surrounding ligaments, and completeness of the lateral ligaments.
Operative procedures
The supramalleolar osteotomy group received prophylactic intravenous antibiotics 30 minutes prior to skin incision. After anesthetic induction, the patient was placed in supine position then a tourniquet was placed at the proximal extremity. A 4-cm longitudinal incision was made in the middle of the anterior ankle to expose the ankle joint cavity and assess whether there was contact between the ankle and tibial joint surfaces. Intraoperatively, lip-like hyperplasia of the tibial joint surface and hyperplasia of the lateral talar surface can be observed, and the passive movement of the ankle was limited. The proliferative bone was removed, and the ankle was moved passively until the range of motion was close to normal. The joint cavity was washed with normal saline and the surgical incision was sutured. A Kirschner wire was used as an osteotomy guide 4–5 cm above the ankle joint. After the osteotomy direction was confirmed on X-ray fluoroscopy, the medial, anterior, and posterior cortices were cut from the anterolateral side parallel to the articular surface of the distal tibia, and the contralateral cortices and periosteum were retained to form a hinge when the osteotomy was opened and were inserted into the wedge-shaped bone block to increase the stability. After satisfactory correction of the varus deformity, a Kirschner wire was used for temporary fixation. Autogenous or allogeneic bone was implanted at the osteotomy site. An anatomical steel plate was used to fix the osteotomy end and afterwards the incision was closed.
The ankle distraction arthroplasty group underwent the same preoperative preparation and the same ankle debridement procedure as the supramalleolar osteotomy group. The ankle joint was placed in a neutral position and the annular external fixator was placed in a suitable position with the extension rod directly opposite the ankle joint activity center. A 2.0-mm-diameter Kirschner wire was used to drill 8 cm below the knee joint, and then two Kirschner wires were drilled 5 cm above the ankle joint and parallel to the knee joint; one Kirschner wire was fixed in front of the calcaneal tubercle, and the other one was fixed in the metatarsal base of the anterior foot. Each ring was reinforced with a threaded needle.
Postoperative management
The incision was routinely dressed and intravenous prophylactic antibiotics were administered. The Kirschner wire hole was wiped with iodophor every day to prevent sinus tract infection. To promote functional recovery of the ankle and prevent postoperative stiffness, both groups began early postoperative rehabilitation exercises. From postoperative day 1, patients were instructed to exercise the toes and quadriceps femoris to prevent lower-extremities deep venous thrombosis. At 1 week postoperatively, the ankle was radiographed from the anteroposterior and lateral aspects. In the ankle distraction arthroplasty group, the external fixator was adjusted as needed; the ankle joint cavity was gradually stretched by about 0.5 mm every day and adjusted every 12 hours until the ankle joint space was pulled out by 5 mm (the external fixator was adjusted at any time based on the patient's condition). The ankle was half loaded by 1 month postoperatively, and full loaded by 2 months postoperatively. At 3 months postoperatively, the external fixator was removed and ankle rehabilitation training was commenced. The supramalleolar osteotomy group performed the same functional exercises to prevent postoperative ankle stiffness and enhance the joint range of motion.
Outcome Measures
All patients were assessed by independent investigator preoperatively and at 6 and 24 months postoperatively. Routine radiological examination comprised anteroposterior and lateral radiographs of the ankle, and full-length lower extremity weight-bearing radiographs. A goniometer was used to measure the ankle angle (TAS, TT, and TLS) and compare them between preoperative and postoperative recorded values.
The range of motion of the affected foot and the healthy foot was measured, including the ranges of varus, valgus, dorsiflexion, and plantarflexion. The American Orthopedic Foot & Ankle Society (AOFAS) ankle-hindfoot score was used to objectively evaluate the pain, ankle function, gait, and force line of the affected ankle and was rated as excellent (90–100 points), good (75–89 points), fair (50–74 points), or poor (0–50 points). Visual analog scales (VAS) scores for used for evaluate pain.
At the last visit, patients were asked to rate their overall satisfaction with their surgical results as excellent, good, fair, or poor. (Table 1)
Table 1 Clinical Rating Scale for Postoperative Ankle function.
Rating
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Description
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Excellent
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Full range of motion equal to the contralateral ankle without pain. Un-restricted work or sports activity.
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Good
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Functional range of motion and stable ankle. Able to return to the previous level with minimal pain with work or sport activity
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Fair
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Functional range of motion, good stability, moderate level of pain, and/or stiffness with activities of daily living and sports activity.
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Poor
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Persistent instability or pain, the same or worse than before surgery.
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To reduce errors and ensure the accuracy of data, all measurements were independently performed by three investigators, and the average of the three results for any measurement was used in the analysis.