Intraoperative Radiation Exposure During Revision Total Ankle Replacement

Intraoperative Radiation Exposure During Midfoot Charcot Reconstruction

While radiation exposure in foot and ankle surgery varies by procedure, attempts to minimize this hazard remain imperative to protect patients and surgeons. Hindfoot deformity correction employs significant radiation through intraoperative fluoroscopy, however, a paucity of data exists concerning Charcot reconstruction. This investigation describes and compares radiation exposure across varying Charcot pathology and fixation constructs. A retrospective chart review of patients undergoing midfoot Charcot reconstruction under large C-arm assistance from 2016-2022 was conducted. Demographics, pathology-specific, and intervention-specific variables were recorded and compared among midfoot reconstructions. The threshold for statistical significance was set at p ≤ .05. Among 40 patients, the average midfoot radiation exposure and fluoroscopy times were 9.5 ± 5.39 mGy and 256.64 ± 130.67 seconds, respectively. There existed no statistically significant difference in radiation exposure (p = .32) or fluoroscopy times (p = .71) among the different midfoot constructs. There existed a statistically significant relationship between radiation exposure with weight (p = .01) body mass index (p = .03) and number of stages (p = .04). Similarly, a relationship existed between fluoroscopy time with weight (p = .02), body mass index (p = .03), and number of beams/screws (p = .003). Due to the complexity of Charcot reconstruction coupled with multiple robust types of fixation, surgeons must remain cognizant of fluoroscopy usage. Moreover, providers who routinely perform Charcot reconstruction should wear personal protective equipment to protect against radiation.

An Analysis of 50 Consecutive Total Ankle Replacements Undergoing Preoperative Computerized Tomography Scan-Based, Engineer-Provided Planning From a Single Noninventor, Nonconsultant Surgeon

Preoperative computerized tomography (CT) scan-based, engineer-provided alignment plans and patient-specific pinning blocks for total ankle replacement (TAR) are available for use in the United States. However, nonbiased studies that justify the additional expense associated with this technology through support of the marketed benefits of less procedural complexity, less intraoperative radiation and reduced surgical time, are lacking. Therefore, to verify the manufacturer's proposed benefits, we sought to investigate our experience with this preoperative CT scan-based, engineer-provided plan and patient-specific pinning blocks during primary TAR. In review of our 50 TAR patients, we found that "perfect" radiographic alignment was not consistently achieved and the accuracy of component prediction was modest. Furthermore, the preoperative plans and patient-specific pinning blocks did not simplify the complexity of our operations since the operative time, intraoperative image intensification time and radiation dose per case all exceeded published historical TAR controls. Interestingly, we identified a significant difference in placement accuracy between the arced and flat-top talar component types that were implanted with the arced being more frequently malaligned. We did not find associations between preoperative deformity severity and accuracy of postoperative alignment. These findings suggest that it is imperative to have surgeons continue to rely on their own surgical planning and experience to achieve optimum radiographic alignment rather than depending on engineer-based recommendations or "surface matched" pinning blocks. Ultimately, we were unable to support the purported benefits of this CT scan-based, engineer-provided alignment plan and patient-specific pinning blocks for this manufacturer's primary TAR systems.

Early outcomes and radiographic alignment of the Infinity total ankle replacement with a minimum of two year follow-up data

BACKGROUND

The Infinity total ankle replacement (Wright Medical Technology, Memphis, TN) is a low profile, fluoroscopically navigated, fixed-bearing device. We hypothesised that the fluoroscopic navigation would allow more accurate alignment of the prosthesis than conventional techniques. We present our minimum two year follow up data of Infinity ankle replacements.

METHODS

All total ankle replacements (TARs) performed at our institution were prospectively followed-up with EQ5-D and MOx-FQ scores as well as intra-operative radiation exposure and radiographic alignment data. Post-operative radiographs were used to measure the alignment of the prostheses. We identified 20 implants with minimum of two year follow up which were compared to a control group of 20 Zenith TAR's (Corin, Cirencester, UK).

RESULTS

Intra-operative fluoroscopic navigation has allowed excellent alignment of all prostheses. Median deviations from 90° alignment to the anatomical axis of the tibia were 1.5° and 1.2° in the anterior-posterior (AP) and lateral planes respectively, compared to 2.8° and 3.1° in the Zenith group. This difference reached significance (p=<0.05) using the Mann-Whitney U test. At 2 years, MOx-FQ scores had fallen from pre-operative mean of 63.9∓17.1 to 15∓12.7. EQ-5D VAS scores had improved from 71.3∓17.3 to 81.4∓9.7 points. Radiation exposure had a mean screening time of 82∓29.4s and a decrease in exposure per patient was observed over time. No patients have undergone, or are awaiting, revision surgery. Complications include one intraoperative medial malleolar tip avulsion fracture, one medial malleolar stress fracture, and one patient who developed CRPS.

CONCLUSIONS

We present evidence that this system achieves better anatomical alignment of the components when compared to techniques without fluoroscopic navigation. The implant survival and complication profile at a minimum of two years is satisfactory.