Clinical and multi-segment kinematic analysis of a modified Grice arthrodesis to correct type II adult-acquired flat-foot

Background: Adult acquired flat foot (AAFF) is a symptomatic postural alteration of the foot due to modifications in bony structures and/or soft tissues supporting the medial longitudinal arch. For the most severe cases, when orthotic solutions do not provide enough pain relief, surgery may be necessary.Research question: Is it possible to restore a normal medial longitudinal arch and to correct the static and dynamic frontal plane alignment of the rearfoot via a modified Grice surgical procedure in AAFF patients? Methods: Eleven patients with stage II AAFF were recruited in the study and underwent the Grice procedure. Patients were assessed via gait analysis using a validated multi-segment foot protocol. Double-leg standing static posture and foot joint kinematics during barefoot walking were measured before surgery and at a mean follow-up of 15 +/- 8 months. Twenty-seven age-matched healthy subjects without foot morphological alterations were used as control. Patients' feet were clinically assessed via the Foot Function Index and the Foot Posture Index. Wil-coxon signed rank test was used to assess differences in kinematic and spatio-temporal parameters between pre -op and follow-up evaluations. 1D statistical parametric mapping was used to assess differences in temporal profiles of foot joint rotations. Results: The clinical indexes significantly improved at post-op (p < 0.05). No differences in sagittal plane static and dynamic joint rotations were observed between pre-op and post-op. In the frontal plane, metatarsus to calcaneus and midfoot to calcaneus rotation angles significantly improved from pre-op to post-op, with the latter resulting consistent with control data. Range of motion and maximum value of the medial longitudinal arch angle were reduced following surgery.Significance: The modified Grice procedure restored a good frontal-plane alignment of rearfoot and midfoot, and the clinical scores provided evidence of its effectiveness in significantly reducing pain and improving the quality of daily activities.