Surgical treatment of end-stage ankle osteoarthritis and its sequelae
Authors:   , van der Plaat Laurens Wessel 
Published: October 2023

The ankle joint is often injured, leading to osteoarthritis with significant impairment. Surgical treatment mainly consists of ankle replacement, or ankle arthrodesis. First-generation ankle prostheses were dissapointing. Newer prostheses were developed, of which the results were reviewed (chapter 2). Clinical results showed improvement at short to midterm follow-up, but radiographic loosening varied considerably from 1% to 45%.

For many patient characteristics historically considered (absolute) contraindications for ankle replacement, like obesity, younger age at implantation, high activity level, diabetes, bilateral ankle osteoarthritis, and etiology of arthritis the scientific basis is lacking (chapter 3).

A meta-analysis of the results of all contemporary ankle prostheses was performed, revealing an calculated revision rate per 100 observed component years of 2.2 (equalling an expected revision rate of 22% at ten-years, chapter 4).

A ten-year survival rate of 67.5% of 254 CCI ankle prostheses was found (chapter 5), patient-reported outcomes were reported. A 54% complication rate was found, with 45% of reoperations attributable to osteolysis/cyst formation/loosening.

In 15 patients with a mean varus deformity of 15 degrees, neutral ankle alignment was achieved through arthroplasty combined with medial malleolar osteotomy, although five required repeat surgery. The AOFAS-score improved from 31 to 81 (chapter 6). In a cohort of 95 arthroplasties with malleolar osteotomy an aseptic revision rate of 25% was found at 5.9 years (chapter 7).

Aseptic loosening of ankle prostheses is frequently associated with osteolytic cysts. A histological analysis of 32 cysts samples showed fibrocytes, fibroblasts, histiocytes and polyethylene particles, 16 contained metal particles, ossifications were found in 26, while 27 contained necrotic areas with amorphous eosinophilic material (chapter 8).

In chapter 9 the results of 47 ankles with an ankle or tibiotalocalcaneal arthrodesis after failed ankle arthroplasty are described. Failure was septic in 21%. After one to three attempts 85% were successfuly fused. A lower fusion rate was found in patients with inflammatory joint disease.

The effects of ankle arthrodesis on metabolic cost and mechanical work during walking were studied in chapter 10, as well as the influence of footwear and the roll-over-shape of the foot-ankle-complex. The results of 15 patients were compared to those of 18 healthy subjects. In all shoe conditions patients exhibited a higher cadence at a walking speed of 1.25 m/s and their steplength was three cm shorter with higher metabolic energy cost.

The double inverted pendulum model was applied to explain these findings. Positive external work was reduced during push-off with the impaired ankle, but no increase in dissipated work during collision with the contralateral leg. No difference in total mechanical work between patients and controls was found. Maximal external work was found when walking barefoot and minimal external work when walking on rocker-bottom shoes. The roll-over shape of the ankle-foot complex did not differ between shoe conditions and groups.

In chapter 11 the sagittal hind-and midfoot motion after ankle arthrodesis, as well as the coronal and sagittal position of the arthrodesis, osteoarthritis of adjacent joints and patient-reported-outcomes are described. The Kellgren and Lawrence scale showed poor interobserver reliability for scoring osteoarthritis of joints of the foot. Likewise, the hindfoot alignment view had poor interobserver reliability. Posterior translation of the talus was routinely obtained and the tibiotalar angle equaled the contralateral side.

The total sagittal range of motion was significantly decreased after ankle arthrodesis, but no significant difference in sagittal motion of the hind- and midfoot between sides was found. Scores on the physical scale of the SF-36, the FAOS, and the Ankle Osteoarthritis Scale were significantly lower after ankle arthrodesis compared to a matched group of healthy control subjects, but satisfaction with the results were high.