How top surgeons treat arthritis

Which procedure? Which ankle? Find out how the experts answer these and other crucial questions.

Part II: [Experts discuss what to expect after ankle surgery]

Ankle arthritis is a disease of relatively young and active patients, yet treatments are often time-limited. The emergence of improved joint replacement designs for the ankle has resulted in a renewed enthusiasm to find an alternative to fusion for disabling ankle pain.

In the first part of this two-part series, some of Europe’s experts on ankle arthritis discuss their approach to this challenging clinical problem.

Charles Saltzman, MD
Moderator

Moderator Charles Saltzman, MD Professor Orthopaedic Surgery, Biomedical Engineering University of Iowa Iowa City, U.S.A. Panelists Beat Hintermann, MD Associate Professor Orthopaedic Surgery University Clinic University Hospital Basel, Switzerland Sandro Giannini, MD Full Professor Clinical Orthopaedics Department, Sixth Division University of Bologna, Rizzoli Orthopaedic Institute Bologna, Italy Michel Bonnin, MD Orthopaedic Surgeon Clinique Sainte Anne Lumiere Lyon, France

Charles Saltzman, MD: How important is ankle joint function? How do patients compensate for loss of motion with the development of ankle arthritis?

Beat Hintermann, MD: The ankle joint forms a functional unit with the subtalar joint that is fundamental for plantigrade, bipedal ambulation. The intact ankle efficiently dissipates the compressive, shear and rotatory forces that are encountered while adapting to weight-bearing and ground reaction forces during different phases of the gait cycle. A large articular contact area provides inherent stability under static load, and dynamic stability is afforded by ligamentous support and balanced muscular forces. The mechanical efficiency of the ankle can be inferred from its relative resistance to primary degenerative joint disease. Cartilage and ligament injury or changes in alignment caused by trauma or inflammatory disease may result in articular degeneration.

In most instances, ankle arthritis is associated with loss of motion, particularly of dorsiflexion. The patient typically increases external rotation of his or her affected leg and reduces the time of single-limb stance, which results in decreased gait efficiency. The patient avoids barefoot walking as he or she feels more comfortable with shoes.

To which extent compensatory dorsi/plantar flexion motion at the subtalar and talonavicular joints is able to compensate for loss of ankle joint motion may depend on several factors, including the functional integrity of these joints and the condition of the soft tissue structures around the ankle joint complex.

Sandro Giannini, MD: Ankle function is particularly important during the stance phase of walking when load has to be transferred from mid- to forefoot. In level walking, about 20º dorsiflexion is necessary. When this motion cannot be achieved, it has to be compensated by additional mobility at the other foot joints. These, when not rigid or arthritic, usually allow an overall mobility of about 20º to 25º, therefore enabling the necessary 20º flexion of the shank with respect to the foot. However, our study on patients 20 years after fusion reveals arthritis at the subtalar and mid-tarsal joints when compared to the controlateral foot, though it’s usually not painful. This was found where arthodesis was obtained at ankle neutral position, at 5º external rotation and 5º valgus, and with a slightly posterior location for the talus. On the other hand, development of arthritis at the subtalar and mid-tarsal joints and of pain were found more important in the cases of ankle arthrodesis performed in equinus and inversion of the subtalar joint. In fact, it is only when the subtalar joint is in its natural position that this can move into both inversion and eversion without overstress, which can result in pain and arthritis. In these cases even the omolateral knee was found altered.

Saltzman: What treatments other than fusion or replacement do you offer patients with end-stage ankle arthritis?

Hintermann: Even when the patient presents with end-stage ankle arthritis, I always try first to find a solution other than fusion or replacement. The most important criteria I am looking for is the shape of the articular surfaces. Loss of joint space on loaded X-ray may be critical, but as long as no subchondral cysts have occurred on both sides of the tibiotalar joint, there is hope to salvage the ankle for a certain time. Another important criteria is to what extent the ankle joint mechanics are preserved. For instance, a valgus ankle with painful talofibular wear, some depression of the lateral tibial plafond and cyst formation on the tibial side (that typically is a floppy ankle with well-preserved motion) will be most promising for supramalleolar varization osteotomy and medial sliding osteotomy of the calcaneus. On the other hand, a painful, rather stiff ankle with anterior extrusion of the talus and large anterior osteophytes that have hindered rolling-gliding movement at the tibiotalar joint, thus provoking posterior gaping of the joint, will not be a promising situation for any alternative treatment.

In my hand, the surgeon’s armamentarium for alternative treatments in the end-stage ankle arthritis should include arthroscopy or arthrotomy for joint debridement and stimulation of cartilage repair (eg, microfracturing); supramalleolar and/or calcaneal osteotomies to correct malalignment; ligament reconstruction to stabilize the ankle joint complex; and tendon reconstruction/transfer to restore muscular function. In practice, success of such measures is sometimes very difficult to estimate. When in doubt, I try to promote the patient for a two-stage treatment, of which the first is an attempt to make the ankle as normal as possible. Fusion, and particularly replacement, in such cases then becomes much easier and more successful in a second step, if necessary.

Giannini: Several options are available for patients with end-stage ankle arthritis. In patients younger than 40 years who are not involved in strenuous work, a conservative treatment can be indicated, even in severe ankle arthritis. This can be achieved by performing the following techniques:

(1) Joint reconstruction and correction using osteotomies, arthrolysis, etc. in cases where the cartilage is still present in the lateral or medial compartment. The goal is to move the load to the unaffected compartment. For example, a patient presents with severe deformity of the ankle joint in valgus, resulting from poorly corrected previous trauma. In this case it is important to align the joint to reduce the localized stress at the lateral region. This is performed by lengthening the fibula and relevant ankle joint reconstruction. With these techniques, and without joint replacement or allograft transplantation, clinical assessment at six years’ follow-up have demonstrated good results in 80% of cases. This procedure allows future joint replacement or allograft transplantation if necessary.

(2) Where ankle morphology is correct, I suggest arthrodiastasis and arthroscopic arthrolysis and creation of microfractures. In these cases, improvement of joint motion and formation of a fibrous cartilage are pursued. Results were initially satisfactory in 50% of the cases, but deterioration is frequent within the first five years’ follow-up.

(3) When these conservative treatments fail, in patients active and younger than 50 years old, with a correct ankle morphology, an allograft transplantation is indicated.

(4) When fusion or replacement are the only options, if an overall 20º to 25º flexion is achievable between the forefoot and the shank, ie, at the other foot joints, I prefer to perform the former.

Saltzman: How do you decide if a patient should have an ankle fusion or an ankle replacement?

Michel Bonnin, MD: The decision between fusion and prosthesis in case of ankle joint pathology is not yet completely “algorithmic” and depends largely on the experience of the surgeon. At the beginning of my experience in total ankle replacement (TAR) in 1993, I was very selective in my indications and did TAR only in “optimal” cases: rheumatoid arthritis or OA without great deformity, ligamentous instability or major stiffness. With time, I observed that functional results and patient satisfaction rates were better with TAR than with fusion and I became more confident.

Progressively, I extended my indications to more difficult cases: patients with extra-articular deformity requiring additional procedures such as subtalar fusion triple arthodesis or supramalleolar tibial osteotomy; patients with stiff equinus ankles, sometimes with previous fusion; and patients with OA due to chronic ankle instability with varus deformity. These cases need careful preoperative planning, with full leg X-ray, CT scan and sometimes dynamic X-ray, to assess the difficulties and prepare the technical solutions (Table 1).

Source: Michel Bonnin

Saltzman: How do you typically perform an ankle fusion and why?

Hintermann:Despite the high satisfaction levels with ankle arthrodesis, it is a salvage procedure with limitations. Thus I try to preserve the hindfoot anatomy as much as possible. I use an anterior approach to expose and debride the joint, and then use two plates to achieve ankle fusion. This technique preserves the ankle joint anatomy as much as possible, which will potentially allow the fusion to be taken apart for ankle arthroplasty when painful degeneration at the subtalar and/or transverse tarsal joints makes further fusion necessary.

Bonnin: My technique depends on the reason why a TAR is contraindicated. If there is no bone deformity but only skin problems, I prefer doing an arthroscopic fusion. I use the technique I described in the French review of orthopaedic surgery in 1995 (Rev. Chir. Orthop., 1995, 81, p.128-135). I use two cannulated screws for fixation (one from fibula to talus and one from tibia to talus) introduced with image intensifier control.

In case of varus or valgus deformity >10º, or in case of bone loss, I prefer doing an open procedure via an anterior approach. Bone cuts are done with an oscillating saw, guided by the extra-medullary guide, to improve bone cut accuracy. Fixation is then done with two anterior staple.

Postoperatively, the patient wears a below-knee cast, without weight-bearing during 45 days and then with full weight-bearing for 45 days.

Saltzman: What do you tell patients about the risks of these surgeries? How long and difficult is the typical postsurgical convalescence period?

A postop X-ray of a total ankle replacement with osteofibula. Courtesy of Michel Bonnin

Hintermann: The outcome of ankle fusion or total ankle prosthesis depends highly on the evaluation and correct management of potential pre- or intraoperative risk factors. Heavy smoking, neuroarthropathic degenerative joint disease (Charcot’s ankle), active or recent infection, significant avascular necrosis of the talus, and a compromised soft-tissue envelope may be high-risk factors for successful isolated tibiotalar fusion, and ankle replacement may not considered at all for these entities. While ankle fusion may be successful, ankle replacement may be critical for neurological dysfunction of the foot or leg, severe non-reconstructible malalignment (20º or greater varus or valgus deformity), or ligamentous instability (for example, chronic ankle instability) of the ankle or hindfoot.

When discussing arthrodesis vs. total ankle arthroplasty with a younger patient who has painful end-stage ankle arthritis, I explain that that TAR may be a viable option for an initial period. If the implant fails and revision arthroplasty is not feasible, then conversion to ankle arthrodesis can be performed. This “two-stage approach” to ankle arthrodesis may preserve the adjacent joints from overuse and secondary osteoarthrosis. Therefore, I use only total ankle implants that require minimal bone resection, thereby saving bone for further revisions or later isolated ankle joint fusion.

As rehabilitation of the diseased ankle takes much longer than after knee or hip replacement, I emphasize that it will take about two years until the final result will be achieved. This is particularly true for posttraumatic osteoarthrosis and ankles that have undergone multiple surgical procedures before, where the soft tissue mantle around the ankle is significantly damaged.

Bonnin: During consultation, I spend a long time explaining to the patient the respective advantages and disadvantages of the two techniques so that the patient can make the decision and choose the technique himself. It is important is to explain that a TAR is not a “normal ankle of somebody 20 years old,” especially in terms of ROM, pain and sport activities. Many patients eligible for TAR are active adults (post-traumatic OA) and can have unrealistic expectations. I say to the patient that choosing a TAR instead of a fusion means choosing to have a better functional result if everything goes well but it also means risking failure.

Postoperatively, the patient is immobilized in a below-the-knee cast for 45 days. Full weight-bearing is allowed immediately or after three weeks in case of Achilles lengthening. I recommend the use of a postop cast for two main reasons: to protect the skin and to prevent any equinus position. This point is critical as the functional prognosis in TAR depends largely on recovering proper dorsiflexion.

After cast removal, the patient is allowed to walk with normal sport shoes without any brace or orthoses. Rehabilitation is limited to walking training, cycling and recovery of ROM, especially for dorsiflexion. Proprioceptive work or muscular training is prohibited during the three first months and is allowed only when the ankle is pain free.

The recovery speed depends mainly on the environment of the ankle joint. If the problem was limited to cartilage degeneration without any stiffness, malalignment or previous surgery, the rehabilitation is easy and needs only two or three months. If there is preoperative stiffness, associated triple arthrodesis, Achilles lengthening or previous surgery the rehabilitation is longer and more difficult.

Painful post-traumatic osteoarthritis 19 years after an ankle fracture, with progressive anterior extrusion of the talus (female patient, 45 years old) (A-B). While performing ankle replacement, attention was paid to restore the center of rotation of talus, thereby balancing the ligaments in the sagittal plane (C-D, intraoperative view).

Saltzman: What type of ankle replacement do you use and why?

Hintermann: I use the Hintegra Total Ankle Prosthesis (Newdeal; Lyon, France), a non-constrained, three-component system that provides inversion/eversion stability. Axial rotation and normal flexion/extension mobility are provided by a mobile-bearing element. Motion limits are dependent on natural soft-tissue constraints: no mechanical prosthetic motion constraints are imposed for any ankle movement with this device. The Hintegra ankle uses all available bone surface for support. The anatomically shaped, flat tibial and talar components essentially resurface the tibia and talar dome, respectively, and wings hemiprosthetically replace degenerate medial and lateral facets (a potential source of pain and impingement). No more than 2 mm to 3 mm of bone removal on each side of the joint is necessary to insert the tibial and talar components.

On the tibial side, most importantly, the bony architecture remains intact, and, in particular, the anterior cortex is preserved. Perfect apposition with the hard subchondral bone is achieved by the flat resection of the bone and the flat surface of the component. Primary stability for coronal plane motion is provided by two screws inserted into the anterior shield in the upper part of oval holes so that the settling process of the component is not hindered by axial loading. On the talar side, additional anterior support is provided by a shield, and pressfit is provided by the slightly curved wings. Two pegs facilitate the insertion of the talar component and provide additional stability, particularly against anterior-posterior translation (additional screw fixation is optional). Another advantage of this concept is the instrumentation that allows reliable component implantation.

In the last five years, I performed more than 400 replacements with the Hintegra ankle. The learning curve was rather long as some adjustments had to be performed, and I needed some time to understand “ligament balancing” in ankle replacement in more detail. However, since then, I am extremely satisfied with the results, and my patients do very well. The revision rate has also dropped to less than 2% even though with our increased experience we were able to take on more complex cases may have been considered for ankle replacement.

Giannini: We are now using the novel Box total ankle prosthesis by Finsbury Instrument Ltd. Clinical trials are in progress here at Rizzoli and in several hospitals in north Italy. This new design results from a long investigation conducted in our research labs, aimed at restoring original joint mobility while maintaining full congruence at the prosthetic articular surfaces.

The guiding and limiting actions of the ligaments seem to have been finally well understood, and recovered in the ankle joint replaced by the Box. Implantation in six anatomical preparations and 22 patients has been very encouraging so far. The motion of the mobile meniscus has been as expected and predicted by the computer models in all these cases. Soon, clinical and biomechanical results at two years follow-up will reveal if any important step forward has been achieved in TAR.

Bonnin: I use the SALTO prosthesis that belongs to the so-called “third generation” group of TAR. These “third- generation” designs are the result of three major improvements:

1. mobile bearings, which reduce stresses on the fixation devices;
2. cementless fixation, which preserves a maximum amount of bone; and,
3. minimal bone resections, which allow reliable anchoring in dense bone.

In this group the SALTO prosthesis has some specificities, which are as follows:

1. The quality of the fixation is optimised: The primary fixation is ensured by closely matching the components to the bone, and enhancing fixation with pegs. On the tibial side, the cylindrical peg provides good compression of the metal base plate onto the distal tibial cut surface at impaction, while eliminating the need for a tibial window. The secondary fixation is provided by bone ingrowth into a dual coating HA coating over a 200-µm thick layer of plasma-sprayed Ti.
2. The anatomic design — the success of a total ankle prosthesis depends mainly on restoring normal or nearly normal ankle kinematics, which requires optimal component positioning and an anatomical bearing surface design. In the SALTO prosthesis, the talar component has an anatomic shape: it is broader anteriorly than posteriorly, and has two different radii of curvature, medially and laterally, that restore near normal joint kinematics.
3. The instrumentation provides accurate, reproducible bone cuts and implant positioning. The technique is based on the use of an extramedullary guide which enables the surgeon to perform the different adjustments step by step. Talar bone cuts are done with an oscillating saw, which ensures closer bone-implant contact than simple decortication of the convex surface. Using two instead of three talar dome cuts simplifies the technique, results in tight component fit and is much more bone-preserving. The technique based on the use of an extramedullary guide enables the surgeon to perform the different adjustments step by step and the talar cuts are linked with tibial cuts.

Dr. Bonnin has a financial interest in a product mentioned in this round table.

Editor’s note: Please read the July/August issue of Orthopaedics Today International for part two of this virtual round table discussion on ankle fusion vs. total ankle replacement.