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There is no defined age where total ankle arthroplasty is considered appropriate for an individual, though most surgeons use the age of 50 years as a benchmark for implantation. Accepted contraindications for this procedure are active infection, avascular necrosis of the talus or tibia and a Charcot neuropathic ankle joint. We report a case of a 57-year-old male who presented with a 15-year history of primary ankle osteoarthritis, having undergone ankle arthroscopy with debridement 10 years prior to presentation. He underwent total ankle arthroplasty and syndesmotic fusion, in combination with a Hoke Achilles tendon lengthening and open repair of the medial malleolar stress fracture.
A 57-year-old male presented with a 15-year history of primary ankle osteoarthritis, having undergone ankle arthroscopy with debridement 10 years prior to presentation. He is an extremely active individual, enjoying hiking, bicycling and wished to maintain this lifestyle following corrective surgery. His ankle pain was significant enough to wake him up at night, and limited his activities during the day. His pain scale was routinely 8/10, with 10 being pain significant enough to request an amputation of the extremity. He had refused an ankle fusion in the past for fear of limiting the activities he enjoys. He presented with severe pain and crepitation across the dorsum of the ankle joint. He had specific tenderness over his medial malleolus where a stress fracture had been diagnosed. His motion was limited to 5 degrees of dorsiflexion and 15 degrees of plantar flexion. His opposite extremity range of motion measured 15 degrees of dorsiflexion and 45 degrees of plantar flexion. His mechanical alignment revealed a very mild valgus deformity. Radiographs are noted in Figure 1 a and b and CT scan in Figure 1 c and d. He underwent total ankle arthroplasty and syndesmotic fusion, in combination with a Hoke Achilles tendon lengthening and open repair of the medial malleolar stress fracture (to prevent a complete fracture from developing). He began physical therapy for passive and active range-of-motion exercises at three weeks postoperatively, and began full weight-bearing in a controlled ankle motion boot locked at neutral at six weeks postoperatively following radiographic confirmation of syndesmotic fusion. The boot was discontinued at three months following surgery, and aggressive walking and cycling were encouraged. By four monthspostoperative, he had achieved 15 degrees of dorsiflexion and 40 degrees of plantar flexion in physical therapy, and returned to golf and cycling. In the clinic, he was noted walking barefoot without a limp. Radiographs and a clinical photo are presented in Figure 2 a, b and c. He suffered one setback with acute cellulitis developing nine months postoperative, which was related to a tinea infection in his foot. This resolved with a short course of intravenous antibiotics, and has not recurred. Currently, at one and a half years following surgery, the patient enjoys a very active lifestyle. He recently returned from an aggressive hiking where he was able to perform unlimited hiking at steep elevations. He participates in all activities without pain.
There is no defined age where total ankle arthroplasty is considered appropriate for an individual, though most surgeons use the age of 50 years as a benchmark for implantation. However, there are many circumstances (i.e. severe rheumatoid disease) where ankle arthroplasty may be appropriate in a younger patient, though it isincumbent upon the surgeon to educate the individual about potential future surgeries. Accepted contraindications for this procedure are active infection, avascular necrosis of the talus or tibia (affecting bone ingrowth), and a Charcot neuropathic ankle joint. Though there are a variety of ankle implants available, currently there are two prostheses used which are frequently. The first resurfaces the ankle joint medially, laterally and superiorly. This prosthesis requires the conversion of a three bone ankle into a two bone ankle through fusion of the syndesmosis. It is FDA-approved for cement implantation only, though most surgeons implant this prosthesis as an ingrowth device. The second prosthesis resurfaces the superior ankle, and requires a mobile-bearing polyethylene component to enhance mobility of the ankle while limiting bone resection. It is currently undergoing an extensive FDA trial. As noted, both prostheses rely on bone in growth for fixation, attempting to resolve one of the major factors leading to early implant failure in previous ankle designs, that is cement implantation. There are a number of theoretical advantages to bone ingrowth prostheses over those that require cement. Bone resection is minimized by direct contact between the prosthesis and nascent bone; cement contact with the surrounding soft tissues (creating thermal necrosis) or bone (creating impingement) is avoided; and accelerated third body wear from cement fragmentation is avoided. Both prostheses have shown more than satisfactory results in medium-term studies. The prosthesis that resurfaces the ankle joint medially, laterally and superiorly underwent an independent review by Pyevich and Saltzman in 1998. With an average 5-year follow-up, 83% of patients reported no pain or mild pain with the prosthesis, and 92% were either extremely satisfied or satisfied with the procedure. Radiographic follow-up of a minimum of two years, revealed a 9% nonunion rate of the syndesmosis and a 29% delayed union rate (>6 months following implantation). Though talar component migration and subsidence were independent of syndesmotic union (or delayed union), 67% of those tibial components demonstrating subsidence were directly affected by the solidity of the syndesmosis. One patient out of the 100 studied required conversion to an ankle fusion within the study period, and three talar and one tibial components required revision. The prosthesis that resurfaces the superior ankle has been studied as both a cemented and uncemented device. Kofoed and Sorensen reviewed 52 cemented ankle arthroplasties demonstrating a 72.7% survival for an osteoarthritic group and 75.5% for a rheumatoid group at 14 years. Hintermann studied 50 consecutive uncemented prostheses that resurface the superior ankle between 1996 and 1999. Three patients required revision for painful lateral impingement at the prosthesis-bone interface (seven in total required secondary surgery); 91% were very satisfied or satisfied with the prosthesis.
The total range of motion averaged 30 degrees with the prosthesis. No migration or subsidence was noted in this short- and medium-term follow-up study.
A time for rehabilitation
Rehabilitation following total ankle arthroplasty is tempered by wound healing. One of the more frequent complications with either prosthesis is marginal or fullthickness necrosis of the surgical incisions. The tenuous nature of the blood supply to the anterior ankle coupled with the lack of adipose and subcutaneous tissue surrounding the deep structures creates a potential for wound complication. We study every patient preoperatively with a noninvasive arterial Doppler test to ensure the blood flow is adequate to the ankle. In addition, the incision is approximated with a running monofilament suture to evenly distribute suture tension and avoid concentration of tension at the knots of an interrupted suture. Most often, a compromised surgical incision can be treated by moist dressing changes and local wound care. Occasionally, however, free muscle transfer is required. Assuming a satisfactory wound, physical therapy is begun to aggressively re-establish the motion achieved at surgery. The therapist must attempt to eliminate micromotion at the prosthesis-bone interface through both axial compression and avoidance of varus/valgus stress. Bone ingrowth generally takes 6-12 weeks, though there is some suggestion that hydroxyapatite-coated implants create satisfactory ingrowth by three weeks following surgery. The physical therapist must also utilize manual massage to lessen the scar contracture around the anterior tendons of the ankle. These tendons are subcutaneous and are thus subject to this motion-restricting complication. Weight-bearing is begun six weeks following surgery with either prosthesis, though it may be delayed in the prosthesis that first resurfaces the ankle joint medially, laterally and superiorly if syndesmotic nonunion is present. Following successful arthroplasty, patients are allowed to resume normal physical activity at three months postoperatively. Finally, supplementary procedures are frequently necessary in this often-complicated patient population. A calcaneal osteotomy, gastrocnemius recession (or Hoke Achilles tendon lengthening), plantar flexion arthrodesis of the first metatarso-cuneiform joint, or lateral ligament reconstruction of the ankle may all be done simultaneously with the arthroplasty procedure. If a triple arthrodesis is required for severe foot deformity, that procedure is generally performed 3-6 months prior to the arthroplasty to enable adequate time for successful fusion. This permits removal of potentially obstructing screws around the talar component.
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