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The INFINITY® Total Ankle System (Wright Medical Technology, Inc., Memphis, TN) is a fourth-generation, fixed-bearing, two-component total ankle replacement. The INFINITY® prosthesis is indicated for end-stage ankle arthritis, but within this category, it has been popular for patients with limited deformity and relatively younger patients where bone stock preservation is important. The INFINITY prosthesis is designed to preserve bone stock by minimizing the amount of bone removed to implant the ankle, using an anterior approach that does not broach the anterior cortex of the tibia and two options for talus resection. The INFINITY prosthesis can be implanted using an extramedullary guide or using PROPHECY®, a CT-based patient-specific alignment guide system. The implant is designed so that postoperative radiographs show the entire bone-implant interface. This chapter explores the surgical technique of implanting the ankle and adds several pearls of knowledge from the design surgeons.

Hindfoot and ankle Charcot neuroarthropathy (CN) deformities can be devastating, limb-threatening illnesses with high rates of complications. The fragmentation and collapse of the transverse tarsal, subtalar, and ankle joints can lead to significant deformity resulting in ulceration, osteomyelitis, and angular deformities. These issues preclude the use of normal gear and cause difficulty with ambulation. Charcot of the hindfoot and particularly of the ankle often has profound instability making bracing difficult or impossible. This can lead to a below-knee amputation in 30–50% of Charcot ankle cases, which, in many cases, can be a more stable outcome rather than limb salvage.

Background: Implant survivorship is dependent on accuracy of implantation and successful soft tissue balancing. System instrumentation for total ankle arthroplasty implantation has a key influence on surgeon accuracy and reproducibility. The purpose of this study was to determine the accuracy and reproducibility of implant position with patient-specific guides for total ankle arthroplasty across multiple surgeons at multiple facilities. Methods: This retrospective, multicenter study included 44 patients who received a total ankle implant (INBONE II Total Ankle System; Wright Medical Technology, Memphis, TN) using PROPHECY patient-specific guides from January 2012 to December 2014. Forty-four patients with an average age of 63.0 years underwent total ankle arthroplasty using this preoperative patient-specific system. Preoperative computed tomography (CT) scans were obtained to assess coronal plane deformity, assess mechanical and anatomic alignment, and build patient-specific guides that referenced bony anatomy. The mean preoperative coronal deformity was 4.6 ± 4.6 degrees (range, 14 degrees varus to 17 degrees valgus). The first postoperative weightbearing radiographs were used to measure coronal and sagittal alignment of the implant vs the anatomic axis of the tibia. Results: In 79.5% of patients, the postoperative implant position of the tibia corresponded to the preoperative plan of the tibia within 3 degrees of the intended target, within 4 degrees in 88.6% of patients, and within 5 degrees in 100% of patients. The tibial component coronal size was correctly predicted in 98% of cases, whereas the talar component was correctly predicted in 80% of cases. Conclusion: The use of patient-specific instrumentation for total ankle arthroplasty provided reliable alignment and reproducibility in the clinical situation similar to that shown in cadaveric testing. This study has shown that the preoperative patient-specific instrumentation provided for accuracy and reproducibility of ankle arthroplasty implantation in a cohort across multiple surgeons and facilities. Level of Evidence: Level III, retrospective comparative series.

Fractures of the distal fibula secondary to rotational ankle injuries are one of the most common injuries requiring surgical intervention. The aim of this study was to describe the anatomy of the distal fibular medullary canal as a means of aiding in surgical management with an intramedullary device. Twenty fresh cadaveric below-knee specimens (group 1, 10 in 2015, group 2, 10 in 2016) were dissected to expose the distal fibular. Fifteen (10 mm each) segments were sectioned with a sagittal saw from the distal tip proximally and measured with a digital caliper. In group I, the widest and narrowest fibular diameter was at the 20-mm interval (mean 15.02 mm) and 90-mm interval (mean 3.51 mm), respectively. From 70 to 120 mm, the mean diameter was less than 4.0 mm. In group 2, the widest and narrowest diameter was at the 20-mm interval (mean 15.05 mm) and 100-mm interval (mean 4.33 mm), respectively. From 70 to 140 mm, the mean diameter was less than 5.0 mm. The combined mean diameter at the 60- to 80-mm intervals were 4.99 ± 1.70, 4.35 ± 1.63, and 4.02 ± 1.35 mm, respectively. Based on our investigation, we propose an intramedullary device diameter of 4.5 to 5.0 mm in diameter with a length of 60 to 80 mm may provide most appropriate bony purchase to achieve acceptable cortical contact for expected osseous compression. Levels of Evidence: Level IV: Cadaveric case series

Background: Focal damage to articular cartilage, also called an osteochondral defect (OCD), can be a cause of pain and decreased range of motion. Recent advancements have led to transplantation techniques using particulated juvenile articular cartilage allograft. This technique has been applied to the first metatarsal head to a very limited degree, with no published results to our knowledge. The aim of this study was to review the clinical results of patients who underwent particulated juvenile cartilage allograft implantation for first metatarsal head OCDs. Methods: We performed a retrospective consecutive case series study. Nine patients, at an average age of 41 years, were treated for symptomatic focal osteochondral defects of the first metatarsal head with particulate cartilage grafting from 2010 to 2016. Patients were contacted by phone to assess interest in returning to the office for follow-up, where weightbearing radiographs of the foot were obtained and a foot examination was performed. Results: At an average follow-up of 3.3 years, 7 of 9 patients reported no pain with recreational activities and no patient required further operations. This patient cohort was physically active, with 6 of 9 listing running as a regular activity. The average overall American Orthopaedic Foot & Ankle Society (AOFAS) Hallux Metatarsophalangeal-Interphalangeal Scale questionnaire score was 85 (maximum 100), AOFAS pain 35.6 (maximum 40), and AOFAS function 40.1 (maximum 45). Patient satisfaction surveys correlated with the AOFAS scores and revealed that 7 of 9 patients were very satisfied with their results, 1 was satisfied, and 1 patient was very dissatisfied. Conclusion: Particulated juvenile cartilage allograft transplantation is a promising treatment option for symptomatic first metatarsophalangeal focal articular cartilage lesions. Further study is needed to demonstrate which lesions respond better to this type of cartilage graft versus traditional marrow-stimulating procedures. Level of Evidence: Level IV, retrospective case series.

Background: The relationship between dorsal plate positioning and final dorsiflexion angle after first metatarsophalangeal (MTP) joint fusion has not been well established. The main purpose of this study was to investigate whether changes in dorsal plate positioning along the longitudinal axis affect fusion dorsiflexion angle, as excessive dorsiflexion angles can lead to poor clinical results. Methods: Ten cadaver foot specimens were randomly assigned to 2 groups for first MTP joint fusion: 1 group used a straight plate, and the other group used a 10-degree precontoured plate. After routine preparation, the plates were placed in an “ideal” position based on clinical and radiological examination. The plates were then moved proximally 3 mm and 6 mm from the initial site, with repeat imaging completed at each position. The radiological dorsiflexion angle was determined for each position, and the results were assessed. Results: Placement of both straight and precontoured plates at positions more proximal from the initial position led to significant increases in dorsiflexion angles ( P = .04), although the percentage change was larger in the precontoured plate group ( P = .01). While placement of the plate 3 mm proximal from the perceived “ideal” position did increase the dorsiflexion angle, the percentage of specimens with dorsiflexion angles in the suggested optimal range changed minimally. Positioning at 6 mm from the starting point, however, led to significantly increased dorsiflexion angles for both plates ( P = .004). Conclusion: Positioning the dorsal plate at more proximal locations leads to increasing dorsiflexion angles. Precontoured plates are more likely to lead to excessive dorsiflexion compared with straight plates regardless of plate position. Clinical Relevance: Fusion at excessive dorsiflexion angles can be minimized with appropriate selection and proper positioning of the dorsal fusion plate along the longitudinal axis.

Reducing unnecessary radiation exposure from medical imaging is paramount. This study assessed whether a laser aiming guide for C-arm fluoroscopy reduced the number of exposures needed to obtain an acceptable image, thereby reducing total fluoroscopy time for hip, knee, and ankle fluoroscopy.An obese cadaver was placed supine on a radiolucent surgical table. Images were obtained by licensed radiologic technologists using a calibrated OEC 9900 Elite C-arm with laser targeting (LT) and without LT (NLT). Dosimeters were placed 1, 3, and 6 ft (30.5, 91.5, and 183 cm) away from the center of the C-arm at 90-degree angles at 2 levels, simulating thyroid and gonadal exposure. Posterior-anterior (PA) images of the bilateral lower extremities were obtained with each technician acquiring 24 centered images (hip, knee, and ankle) using both LT and NLT C-arm fluoroscopy.Total fluoroscopy time was reduced by 19% when using LT with a 39% reduction for the knee and a 29% reduction for the ankle. The addition of LT improved the likelihood of obtaining a centered image for knees and ankles but not for hips. The gonadal dosimetry data were significantly higher than the thyroid dosimetry badges at 1 ft. At the 3-ft zone, only trace amounts of radiation were detected; the 6-ft zone reported no radiation exposure in either group.LT helped with imaging knees and ankles with statistically significant reductions in fluoroscopy time and a statistically significant improvement of image quality defined as obtaining a centered PA image faster. The dosimetry badges detected minimal exposure at 3 ft and no detectable exposure at 6 ft at both levels.

Total ankle replacement (TAR) is a viable alternative to ankle fusion in certain patients with end-stage ankle arthritis. Despite the importance of understanding alignment and movement of the prosthesis, there is no standardized radiographic method for evaluating the position and movement of the INBONE 2 prosthesis. The aims of this study were to describe a radiographic measurement protocol for INBONE 2 for clinical practice and research while determining the interobserver and intraobserver reliability using standard weightbearing radiographs. Fifteen patients were randomly selected with operative dates from January 2011 to January 2014 who underwent primary TAR using the INBONE 2 prosthesis. Most recent preoperative and first postoperative weightbearing anteroposterior and lateral radiographs were pulled and deidentified. Three foot and ankle surgeons blinded from the patient selection and deidentification, measured the described measurements on separate occasions. Intraobserver reliability: surgeon 1 had acceptable reliability for 9 of 13 continuous radiographic measurements (69.2%), surgeon 2 had acceptable reliability for 8 of 13 measurements (61.5%), and surgeon 3 had acceptable reliability for 12 of 13 measurements (92.3%). Interobserver reliability: among the first measurements, 6 of 13 continuous radiographic measurements (46.2%) had acceptable reliability. Among the second measurements, 7 of 13 measurements (53.8%) had acceptable reliability. Among the first and second measurements combined, 7 of 13 measurements (53.8%) had acceptable reliability. This study promotes the need for meticulous evaluation of annual radiographic findings following TAR in an effort to avoid catastrophic failure and represents moderate agreement can be obtained by employing the proposed measurements for surveillance of INBONE 2 TAR at annual postoperative visits. Measurements on the anteroposterior radiograph appear to demonstrate more consistent results for surveillance than lateral measurements. The intraobserver reliability results were somewhat superior to the interobserver reliability, implying more relevance for a single surgeon applying these measurements annually for postoperative surveillance. Levels of Evidence: Diagnostic, Level III

The INFINITY® Total Ankle System (Wright Medical Technology, Inc., Memphis, TN) (WMT) is a modern, fourth-generation, fixed-bearing, two-component total ankle replacement. Specific parameters of deformity correction achievable with this prosthesis, like any other, are based on the experience of the surgeon more so than by the engineered characteristics of the implant itself. However, as with other resurfacing-type prostheses, this prosthesis is ideal for patients with limited deformity and relatively younger patients where maintenance of bone stock is critical, especially on the talar side of the joint. Optimal maintenance of talar bone stock is a principle that is accepted by total ankle replacement surgeons and allows maximal surgical options when revision surgery is required.

Category: Midfoot/Forefoot Introduction/Purpose: Focal damage to articular cartilage and the supporting subchondral plate, commonly referred to as an osteochondral defect (OCD), can be a cause of joint pain and subsequent decreased range of motion. There are few studies specifically describing these lesions in the first metatarsophalangeal (MTP) joint, where they are traditionally grouped into hallux rigidus. There exists an opportunity for early detection and intervention with the intent to prevent deterioration and improve patient outcomes. One contemporary treatment concept is to implant particulated juvenile cartilage allograft to restore articular cartilage. The aim of our study was to review the clinical results of patients that had undergone this procedure for first metatarsal head OCDs. Methods: After IRB approval, a retrospective review of a consecutive case series was studied utilizing the records of three foot and ankle surgeons. Inclusion criteria included all adult patients who were a minimum of one year post surgery and consented to participate. Patient demographics and preoperative visual analog scale (VAS) pain level were recorded from a standardized intake sheet. From the operative note, the OCD size and location was recorded, as well as any concomitant procedures. At a minimum follow up of one year, we obtained objective measurements of arthritis grade and subjective considerations of pain and function, including VAS pain level, Foot Function Index (FFI) questionnaire, the American Orthopaedic Foot and Ankle Society (AOFAS) Hallux Metatarsophalangeal-Interphalangeal scale, and an overall patient satisfaction score. Results: Nine patients met inclusion criteria, 4 males and 5 females. The average age was 41 years old (±11.77, range 21-65). The mean preoperative VAS pain score was 57.50 (±18.32, range 30-80). Four OCDs were located centrally on the first metatarsal head. The average OCD size intraoperatively was 30 mm2 (range 16-49). The average time since surgery was 3.26 years (±1.21, range 1.41-5.62). Average first MTP dorsiflexion was 41.78 degrees (±20.70, range 6-70). The average postoperative hallux rigidus classification was grade 2 (range 1-3). The mean VAS pain score improved to 5.22 (±8.44, range 0-20). The average AOFAS score was 88 (±15.91, range 52-100). The average FFI score was 8.04 (±12.60, range 0-30.6). All but one patient were satisfied or very satisfied with their results. Conclusion: At an average of 3.26 years postoperatively, patients had improved pain, did not show significant progression of their first MTP joint degeneration, and were satisfied with their results. Patients reported very little, if any, limitations in their activity level. We believe that articular damage of the first MTP should be viewed in the same way as OCD lesions in larger joints with emphasis on early detection and treatment to avoid the progression to arthritis. Particulated juvenile cartilage allograft is a valuable tool for surgeons to use in treating focal articular defects of the first metatarsal head.