Patient-Specific Instrumentation and Total Ankle Arthroplasty

J.K.H. Yau, B.R. Emmerson, R. Kakwani, A. Murty, D. Townshend

Introduction: Total Ankle Arthroplasty (TAA) can now be performed using Patient Specific Instrumentation (PSI). Advantages include the ability to pre-operatively plan bone resections and implant position and reduce the number of intra-operative surgical steps. The aim of this study was to compare PSI with Standard Instrumentation (SI) in a non-randomised retrospective cohort study with respect to patient reported outcomes, tourniquet time, fluoroscopy time and post-operative alignment.

Methods: 159 patients (111 male, 48 female) undergoing a total of 168 INFINITY TAA using PSI (Prophecy, Wright Medical Technology) or SI between 2014 and 2020 were included with a minimum follow up of 12 months. Patient reported outcome measures (PROMS) were obtained pre-operatively and at one year and included the Manchester-Oxford Foot Questionnaire (MOXFQ), Ankle Osteoarthritis Scale (AOS) and EQ-5D Index. Coronal plane deformity correction was assessed using the midline tibiotalar angle (MTTA). Demographics, tourniquet time and intra-operative fluoroscopy times were obtained from the hospital records.

Results: There were 106 TAA in the SI group and 62 TAA in the PSI group. There was no significant difference in total MOXFQ, AOS or EQ5D. There was however a significant difference (p=.032) in favour of PSI in the walking/standing domain of the MOXFQ at 12 months. There was a significantly reduced tourniquet time (PSI mean: 95.39 mins, SI mean: 116.87 mins, p<.001) and radiation exposure (PSI mean: 31 seconds, SI mean: 53 seconds, p<.001). The angular correction was more accurate in the PSI group (PSI mean: 1.29°, SI mean: 2.26°, p=.005).

Conclusions: This study supports the use of patient-specific instrumentation to decrease operative time, reduce intraoperative fluoroscopy and improve the accuracy of implantation in TAA. The walking/standing domain of the MOXFQ has been shown to be the most sensitive to change and in this study demonstrated a further potential benefit.