Do degree of coronal plane deformity and patient related factors affect union and outcome of Arthroscopic versus Open Ankle Arthrodesis?

BACKGROUND

This study aimed to analyse if union and outcome of Arthroscopic Ankle Arthrodesis (AAA) versus Open Ankle Arthrodesis (OAA) were influenced by the extent of coronal plane deformity and to report if patient related factors influence union.

METHODS

A total of 122 ankle arthrodesis procedures were included in the study. These were divided into two groups; Group A (n = 99) with deformity less than 15° and Group B (n = 23) with deformity greater than or equal to 15°. Data was collected on patient demographics, medical comorbidities (smoking, diabetes, obesity) and time to union. Patient reported outcome measures (PROMs) evaluated were Manchester Oxford Foot Questionnaire, EuroQol-5D and EuroQol visual analogue health thermometer (EQ-VAS).

RESULTS

The mean follow-up in Group A and B was 74.87 and 89.17 months respectively. The average deformity in Group A was 4.9° for AAA and 5.8° for OAA. In Group B it was 18.9° (maximum 28° varus) for AAA and 22.1° (maximum 41° valgus) for OAA. The overall union rate was 95% in Group A (AAA-94%; OAA-100%; [p = 0.20]) and 87% in Group B (AAA-100%; OAA-67%; [p = 0.02]). Mean time to union was 13.2 weeks in Group A (AAA-13.3 weeks; OAA-12.8 weeks; [p = 0.73]) compared to 12.4 weeks for Group B (AAA-12.9 weeks; OAA-11.8 weeks; [p = 0.56]). Irrespective of the extent of deformity and type of surgery, smokers had a 10 times higher likelihood of non-union (p = 0.03). In Group A, none of the PROMs showed significant difference between AAA and OAA. In Group B, EQ-VAS score reached statistical significance (p = 0.03) in favour of AAA whereas other PROMs showed no difference.

CONCLUSION

AAA is reproducible in achieving union in end stage ankle arthritis and good PROMs can be expected even in ankles with larger deformities. Regardless of the type of surgery and extent of deformity, smoking is a significant risk factor for non-union.

LEVEL OF EVIDENCE: Level III, retrospective comparative series.