Arthroscopic Ankle Fusion Methods

Timothy C. Fitzgibbons

David J. Inda

INDICATIONS

Multiple open surgical techniques have been described for ankle arthrodesis. In the 1980s, advancements in arthroscopic instrumentation and techniques made arthroscopic ankle arthrodesis (AAA) feasible.

The early experience with AAA was fraught with many complications and discouraged many from doing the procedure. In 1996, our published complication rate using a skeletal pin distraction technique was 55%.¹ Almost all complications were due to the use of external distraction. After we discontinued using the external distraction, the complication rate significantly decreased. Other authors in the 1990s reported similar improved results.²^, ³^, ⁴^, ⁵^, ⁶^, ⁷^, ⁸^, ⁹^, ¹⁰^, ¹¹^, ¹²^, ¹³^, ¹⁴

More recent reports in the literature have been quite favorable.¹⁵^, ¹⁶^, ¹⁷^, ¹⁸^, ¹⁹^, ²⁰^, ²¹^, ²²^, ²³^, ²⁴^, ²⁵^, ²⁶^, ²⁷^, ²⁸^, ²⁹^, ³⁰^, ³¹^, ³²^, ³³^, ³⁴ Ferkel in 2005 documented a 97% fusion rate with minimal complications.¹⁹ Rinson, Robinson, and Allen in 2005 published a 92.4% fusion rate, shorter time to fusion and minor complications.³⁵ As noted above, our more recent experience has been similar.

This chapter describes our technique of arthroscopic ankle fusion that has evolved over a 20-year period. The general indications for arthroscopic ankle fusion are the same as for open ankle fusion: most commonly degenerative or inflammatory arthritis with loss of articular cartilage.

Critics have questioned the technique of arthroscopic ankle fusion claiming that it takes considerable time and effort to learn the procedure. Most studies demonstrate the fusion rates of open and arthroscopic techniques to be about the same.³⁶^, ³⁷^, ³⁸^, ³⁹^, ⁴⁰^, ⁴¹

The advantages of AAA in our opinion are the following:

Maintenance of the inherent stability of the ankle makes it easier for positioning of the ankle in the optimum position at the time of screw insertion.
The technique preserves the fibula and medial malleolus for possible future total ankle arthroplasty.
There is decreased morbidity for the patient, especially less pain and fewer wound complications.

The disadvantages of AAA have been that it does not allow for the correction of significant deformities. However, we and others have found that with the addition of supplemental procedures such as calcaneal osteotomies, tendo Achilles lengthening, and dorsiflexion producing first metatarsal osteotomies the indications can be broadened to a larger population of patients (Table 11-1).

We feel that this procedure should be chosen if the surgeon is an experienced ankle arthroscopist and comfortable with this approach.

PATIENT POSITIONING AND EQUIPMENT

The patient is positioned on a regular operating table with a bump under the affected hip and padding of the other leg in anticipation of flexing the foot of the bed at the time of screw insertion.

We forego pin-based distraction techniques in favor of no distraction or simple noninvasive distraction using a foot strap apparatus (Fig. 11-1).

We place a high-thigh tourniquet on the patient’s thigh, but it is not always inflated. The use of preoperative 0.25% Marcaine with epinephrine and adequate distention is usually adequate for intra-articular hemostasis without tourniquet inflation, but the tourniquet is available if visualization is not adequate. An infusion pump is used to facilitate adequate distention.

A sterile, padded Mayo stand is prepared. This is used at the end of the procedure in placing the screws and has been found to be quite helpful (Fig. 11-2).

Although a small joint arthroscopy set can be used, we have found that using the 4-mm 30-degree large joint arthroscope is better. Because there is no concern for “scuffing” the articular surface in these cases, a large arthroscope not only gives better visualization and better distension but also allows for better fragment evacuation.

The use of large joint shavers and burrs is also recommended. We use the 5-mm aggressive resectors, 4- or 5-mm round burrs and occasionally a 5-mm egg burr. In
the recent years, however, we have found that use of an aggressive resector only in combination with various size curettes is adequate. The use of these burrs can create large holes or furrows that are detrimental to maintaining optimally congruent fusion surfaces.

TABLE 11-1. Arthroscopic Ankle Fusion

Advantages

Maintains inherent stability of the ankle
Preserves malleoli
Decreased morbidity

Disadvantages

Learning curve for the surgeon
Does not allow for correction of deformity—although addition of supplemental procedures does allow for expansion of indications

Figure 11-1. Example of a soft tissue ankle distractor used occasionally in arthroscopic ankle fusion.

Other instruments include curved curettes, osteotomes, an inflow cannula, and large joint grasping tools (Fig. 11-3).

We routinely insert bone graft at the fusion site before inserting our fixation. Our protocol is to obtain bone marrow aspirate from the ipsilateral iliac crest using an 11-gauge bone marrow aspiration needle with a heparinized syringe. This is then mixed with demineralized bone matrix powder and is injected into the joint prior to placement of fixation (Fig. 11-4). For this reason the iliac crest is prepped out.

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