The “Young” Arthritic Ankle: Treatment Options in Arthrodesis

CHAPTER PREVIEW

CHAPTER SYNOPSIS:

Tibiotalar arthritis in the young patient that warrants fusion is typically due to either posttraumatic or inflammatory ankle pathology. The decision for tibiotalar fusion is based on pain relief for the patient, not on any belief in enhanced function. There are a variety of techniques that can be used to accomplish the ankle fusion, and the choice depends on both the pathology of the bone and surrounding soft tissue, as well as surgeon’s preference. Both arthroscopic and open techniques are discussed. The key to a successful fusion is the health of the bone and the position in which the tibiotalar joint is placed. The effectiveness of the subtalar joint complex to dissipate the stress caused by loss of ankle motion is directly related to the fixed position of the talus. Last, surgeons should remember that the patient’s gait and cadence will be affected, and the stresses placed on the remaining joints in the midfoot will increase once the ankle is fused. This may predispose these patients to earlier-than-expected arthritis in these lesser joints of the foot.

IMPORTANT POINTS:

1

Obtain preoperative weight-bearing radiographs of the ankle and foot. Computed tomography scanning or magnetic imaging is done if bone anatomy, quantity, or quality is in question. Talar dome avascular necrosis may require bone graft/allograft to augment fusion and prevent nonunion/malunion.
2

Solid fusion can be expected in 90% or more low-risk (no tobacco use, diabetes, etc.) patients.
3

Expect approximately 10 degrees of dorsiflexion/plantarflexion through the midfoot tarsal joints after ankle fusion.
4

Evidence of radiographic fusion typically is seen in 12 weeks.
5

Patient’s stride will shorten, but ambulation velocity and cadence often are unchanged.
6

Further postankle fusion improvements in ambulation will be seen with shoe wear compared with barefoot.
7

Patients with a history of a past ankle infection, Charcot arthropathy, peripheral vascular disease, or related disorders may not be candidates for an isolated ankle fusion.
8

Both positional deformity of the ankle and poor bone stock are relative contraindications for arthroscopic arthrodesis.
9

Subtalar arthritis, if present, may be the true source of pain. Selected joint injections are useful to help isolate the source of pain.

CLINICAL/SURGICAL PEARLS:

1

Failure to remove all articular cartilage (especially posterior ankle joint) will likely cause a delayed union/nonunion.
2

Transecting the Achilles tendon in an ankle with an equinus ankle may help correct the plantar flexing deforming forces and make positioning of the foot easier before fusion.
3

Cannulated screws (6.5 mm or larger) in separate planes of fixation through the ankle joint will offer the strongest biomechanical construct for fusion using the anterior approach.
4

Attention to foot position before fusion cannot be overemphasized. Surgeons should err on the side of ankle dorsiflexion/valgus hindfoot rather than plantarflexion/hindfoot varus.
5

“Homerun” screw from distal tibia into talar neck offers most solid arthrodesis fixation.
6

Large C-arm should be used to check radiographic alignment/hardware position.
7

Autologous bone graft to facilitate fusion at the tibiotalar joint can be obtained from the proximal tibia.
8

Prime both the distal tibia and talar dome subchondral bone areas with a 2.5-mm drill to create a porous surface before fusion. Use the soft tissue guide to position drill.
9

Threads of screws must completely cross ankle joint.
10

There should be up to 3 months of non–weight-bearing. Initial protection in a cast is recommended to minimize motion at the fusion site. Patient may need an ankle-foot orthosis for 6 months to minimize anterior stress with weight-bearing.

Arthroscopic Approach:

1

This approach should only be undertaken by experienced ankle arthroscopists.
2

This approach should be used on ankles with minimum deformity.
3

A fixed varus/valgus alignment of the ankle joint of 10 degrees or more, talar avascular necrosis, and a history of ankle joint infection are contraindicated for arthroscopic approach.
4

Standard two-portal (anterior medial and lateral) or three-portal (addition of a posterolateral portal) ankle arthroscopy is used.
5

Ankle joint distraction will be used in beginning of case for joint preparation/debridement only. It should be released for joint fusion/hardware placement.
6

Anatomic alignment of the joint must be maintained during cartilage removal.
7

Standard screw placement techniques apply.
8

Severe ankle arthrosis with blocking osteophytes makes arthroscopic visualization difficult.
9

Arthroscopic fusion is not quicker and does not heal faster than open techniques.

Open Approach:

1

The choice of soft tissue approach depends on the condition of the soft tissue envelope and the health of or defects in the underlying bone.
2

Remove all sites of bony impingement to allow proper position of fusion.
3

The anterior ankle approach through the extensor hallicus longus and tibialis anterior tendon interval is best for treating anterior tibial or talar defects.
4

Wound complications can be significant with the anterior approach as skin loss exposes tendons and neurovascular structures.
5

Lateral approach allows easier access to the posterior tibiotalar joint surfaces.
6

When using the lateral transfibular approach, resect 5 mm of distal fibula from fibula to protect against contact and pain at the fibula osteotomy site.
7

Autologous cancellous bone from the ipsilateral proximal tibia can be used to fill defects in the fusion contact surface. Typically, less than 10 cm ²of graft is needed.

VIDEO AVAILABLE:

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Ankle fusion patient.
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Surgical treatment of end-stage ankle arthrosis.
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Arthrofusion.
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Conventional transfibular ankle fusion.
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ROMankle fusion.

HISTORY/INTRODUCTION/SCOPE OF THE PROBLEM

Fusion of the tibiotalar joint has been shown to be one of the most predictable methods of treating painful arthritis of the ankle. Although there are numerous methods for creating a stable arthrodesis, the relief of painful symptoms once fusion is achieved has proved to be consistent. ^–Unlike in the hip and knee, primary osteoarthritis of the ankle is rare. The vast majority of arthritic ankles in younger patients are due to a traumatic injury. In many cases, the injury causes either bone loss or changes to anatomic position, making joint salvage or replacement difficult. Furthermore, younger patients with their higher activity levels and longer life expectancies will have a more predictable return to an active lifestyle with an appropriately aligned ankle fusion over a replacement.

Fusion of the tibiotalar joint can also be very functionally limiting. This joint is the most important joint of the foot and ankle complex for normal joint mechanics. Normally about 10 degrees of dorsiflexion is needed for normal weight progression from the hindfoot to the forefoot during single limb stance. Loss of the tibiotalar joint makes this normal transference difficult. Choosing an ankle fusion for a young patient should be considered a last resort treatment for disabling pain. The procedure is best thought of as a means of relieving pain, not enhancing function.

Patients complaining of “ankle pain” must be carefully evaluated both clinically and radiographically. Other types of pathology (i.e., anterior tibial tendonitis or neuromas), as well as talonavicular and subtalar arthropathy, can be confused as ankle pain. Furthermore, alignment of the foot, ankle, and the rest of the lower extremity must be examined for potential causes of deformity or pain. However, those with documented tibiotalar arthritis, as noted on weight-bearing ankle radiographs, as well as on clinical presentation (pain that is activity related), should be counseled on the available treatment modalities available to them. In patients with a suspicion of having profound bony abnormalities, such as talar avascular necrosis or posttraumatic bone loss, a presurgical computed tomography scan of the foot and ankle may be indicated ( Fig. 9-1 ).

Patients who will benefit most from tibiotalar arthrodesis are those who have had a prolonged course of ankle pain/activity disability that has been recalcitrant to conservative treatments (i.e., nonsteroidal anti-inflammatory drugs, bracing, shoe wear modifications). If there is any question about the source of the ankle pain, a simple selective injection (using contrast dye under fluoroscopy) of a local anesthetic (marcaine/lidocaine) is put into the joint. This should relieve the majority of the symptoms and help guide the surgeon in his or her treatment plan. If 75% of the patient’s symptoms are not relieved, then another source of the joint pain should be sought. Always be aware of the possibility of subtalar arthritis masked as ankle pain. Finally, remember that radiographic appearance does not always correlate with pain.

Once a patient is considered a candidate for ankle fusion, the dialogue between patient and physician should include postoperative expectations versus risks and benefits. Lifestyle modifications, including non–weight-bearing status in the immediate postoperative period and other similar alterations in the patient’s normal daily life, must be discussed.

Preoperatively, patients should be informed of the expected calf atrophy, decreased walking speed due to a shorter stride, and a loss of up to 70% of their midfoot/hindfoot sagittal plane motion. In addition, they should be informed that once the ankle is fused, the remainder of the sagittal motion will come predominantly from the transverse tarsal joints. This can lead to early symptomatic degenerative joint disease in these lesser midfoot, as well as subtalar joints that must now “take up the slack” for the fused ankle. Last, the patient should understand that jumping, running, and probably jogging will be difficult, if not impossible, after the ankle arthrodesis due to the mechanical restraints of the ankle fusion. Cycling, walking,and some low-impact aerobic workout machines will be better tolerated and allow improved rehabilitation and physical fitness. This being said, one study found that at an average of more than 20 years after ankle fusion, 67% of patients were happy with their results and 92% would recommend it to someone else. Furthermore, it was shown that the variations in gait following ankle fusion diminish with shoe wear compared with being barefoot.

Complications after ankle arthrodesis can be significant. The most frequent are nonunions, malunions, wound breakdown, and infections. The risk of malunion and nonunions can be increased with transmalleolar osteotomies, avascular necrosis of the talus (up to 41% nonunion rate ), Charcot neuropathies, failed ankle arthroplasties, incomplete removal of articular cartilage, bone thermal necrosis from high-speed burs, and insufficient immobilization following fusion. These postoperative problems can be increased with early weight-bearing, smoking (up to 16 times higher nonunion rate), diabetes, and alcohol use. Careful screening of patients before surgery is important, as a failed ankle arthrodesis is difficult to treat or revise and often frustrating for both patient and surgeon.

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