The incidence of Gissane angle impingement and accessory anterolateral facet of the talus in adult acquired flat foot: the need for an increased awareness of non-arthritic lateral hindfoot pain

A. Mirza, Y. Shaik, R. Botchu, H. Prem

Introduction: In Adult Acquired Flatfoot (AAF) classifications (Stage 3 of Johnson and Strom, Bluman) lateral hindfoot pain is associated with subtalar joint arthritis (STA) and arthrodesis is recommended. Bluman reports sinus tarsi pain, Gissane Angle sclerosis and subtalar joint space loss as Grade 3 changes. We hypothesise that the occurrence of lateral pain from Gissane Angle Impingement (GAI) is independent of subtalar arthritis and is dependent on the extent of the deformity and/or the presence of an Accessory Anterolateral Facet of Talus (AAFT).

Methods: Radiographs and MRI images of AAF done between May 2015 and January 2018 were reviewed. Meary's angle, Talonavicular coverage angle, subtalar articular status, Gissane Angle bone oedema, the presence of an AAFT, calcaneofibular impingement (CFI) and hindfoot valgus angle (HFVA) were assessed.

Results: 28 (24 female, 4 male) patients with a mean age of 54.2 years were included. The mean Meary's angle was 32 degrees and the mean talonavicular coverage angle was 23.8 degrees. The mean HFVA was 33.6.
14 patients demonstrated MR signal change in both talar and calcaneal sides of the Gissane Angle and 2 patients demonstrated unilateral signal change. An AAFT was seen in the MRI images of 10 of these patients. Only 9 patients demonstrated CFI. There was STA in 11 patients. CFI & STA coexisted in 4 patients. Presence of an AAFT was found to significantly reduce the measured tip-apex distance within the Gissane Angle (mean 3.2mm to mean 2.2mm) and was also associated with increased bone oedema.

Discussion: Our cohort of patients demonstrates significant pes planus deformity and a high prevalence of GAI on MRI scans. GAI was seen more frequently than CFI. GAI appears independent of STA and arthrodesis need not be considered. Identifying the causes of lateral pain and the presence of an AAFT significantly influences surgical planning.