Patient Specific Instrumentation (PSI) is thought to quicken joint arthroplasty surgery by shortening the operation time and improving alignment. Studies about the learning curve of PSI for total ankle replacement (TAR) are lacking because it was only introduced in 2014.

The investigators believe that PSI could give a beginning ankle surgeon, or surgeons new to TAR, an advantage since PSI facilitates the complex TAR procedure. As such, the availability of TAR in Dutch patients with end-stage ankle osteoarthritis could be extended. To estimate this potential of PSI for TAR, the investigators aim (1) to compare the alignment accuracy of TAR performed using PSI between a beginning and an experienced orthopedic surgeon, and (2) to determine the learning curve of TAR performed using PSI for a beginning foot and ankle specialist by comparing the operative time, complications, and patient-reported outcomes with those of an experienced specialist.

Total ankle replacement (TAR) as treatment of end-stage osteoarthritis of the ankle is gaining popularity past few years, resulting in a growing number of TAR placed each year. This is an important progression because osteoarthritis of the ankle is suggested to be as disabling as chronic kidney injury or heart failure. Though TAR is proposed to be superior to ankle arthrodesis (AA) with regard to patient quality of life, it is not commonly available in the Netherlands. Merely 149 TARs were registered nationally in 2020.

Patient Specific Instrumentation (PSI) is thought to quicken the process by shortening the operation time and improving alignment. Though the literature is submerged in studies about the learning curves of PSI and TAR, research about the learning curve of PSI TAR is lacking because it was only introduced in 2014. Preliminary results showed that the use of PSI resulted in lower average pain scores and earlier recovery compared to TAR using standard instrumentation. Yet the absolute advantage of PSI was not established because of limited research. Furthermore, all previous studies were performed by skilled surgeons to eliminate the bias of inexperience.

The investigators believe that PSI could give a beginning ankle surgeon, or surgeon new to TAR, an advantage since PSI facilitates the complex TAR procedure. As such, the availability of TAR in Dutch patients with end-stage ankle osteoarthritis could be extended. To estimate this potential of PSI for TAR, the investigators aim (1) to compare the alignment accuracy of TAR performed using PSI between a beginning and an experienced orthopedic surgeon, and (2) to determine the learning curve of TAR performed using PSI for a beginning foot and ankle specialist by comparing the operative time, complications, and patient-reported outcomes with those of an experienced specialist. It is hypothesized that the alignment of PSI TAR performed by a beginning orthopedic surgeon does not significantly differ from one performed by an experienced surgeon. Furthermore, it is hypothesized that the operative time, complications, and patient-reported outcomes do not significantly differ between a beginning and an experienced orthopedic surgeon.

Inclusion Criteria:

• Patient can understand the study's meaning and is willing to sign the study-specific Informed Patient Consent Form.
• Patient received the implantation of Infinity or Inbone prosthesis using PROPHECY PSI for primary TAR in 2022.
• There are at least 3 months of follow-up data for this patient.
• Patient can lay still during the length of duration of the CT-scan.

Exclusion Criteria:

• If per-operative the use of the PSI guides was abandoned.
• Patients that underwent revision surgery (defined as original tibia of talar component change or removal).
• Patients that endured other diseases that significantly impacted the post-operative period following TAR (e.g. amputation, severe extremity dysfunction due to a neurological or vascular impairment or trauma).

All patients that received primary TAR pre-operatively planned using PROPHECY PSI in 2022. Both traumatic and non-traumatic osteoarthritis are included.