Accuracy of a Patient-Specific Total Ankle Arthroplasty Instrumentation.

BACKGROUND: Total ankle arthroplasty (TAA) is a preferred surgical option for end-stage ankle osteoarthritis; however, it is a demanding procedure with a higher historical rate of revision compared with ankle fusion. Patient-specific instrumentation (PSI) has been introduced to optimize prosthesis alignment and theoretically overall improve TAA outcomes. The goal of this study is to report on the experience and surgical outcomes of one implant with specific evaluation of the accuracy and reproducibility of the system with respect to prosthesis alignment and prediction of implant size. METHODS: A retrospective, multicentered study involving 4 foot and ankle fellowship-trained orthopaedic surgeon's patients undergoing TAA between January 1, 2015, and December 31, 2018, using the PROPHECY PSI system. RESULTS: 80 TAA procedures were performed. On average the postoperative tibial component alignment was 89.9 (range, 86.1-96.5) degrees in the coronal plane, with a mean sagittal alignment of 88.1 (range, 81.3-96.7) degrees. The mean deviation from neutral sagittal alignment improved from 4.9 ± 3.9 degrees preoperatively to 2.7 ± 1.7 degrees postoperatively, whereas the mean coronal alignment improved from 3.3 ± 2.5 degrees to 1.3 ± 1.1 degrees. The PSI software correctly determined the tibial implant size in 70 patients (89%). Prediction of talar implant sizing was less accurate than the tibial component, with 56 patients (71%) using the predicted sized implant. The overall implant survival at a mean follow-up of 45 months (range, 27-76) was 97.5%. CONCLUSION: We found that this PSI system accurately and reliably assisted in implant total ankle prosthesis positioning within a clinically acceptable margin and without significant outliers. Prediction of implant size was not as accurate as component orientation. LEVEL OF EVIDENCE: Level III, retrospective study.

The World Health Organization Fracture Risk Assessment Tool (FRAX) underestimates incident and recurrent fractures in consecutive patients with fragility fractures.

CONTEXT: The World Health Organization Fracture Risk Assessment tool (FRAX) was developed to identify patients at risk of sustaining a fragility fracture (FF). OBJECTIVE: The objective of the study was to evaluate estimated FRAX probabilities of FF at the time of a FF and to compare them with the observed incidence of recurrent FF. METHODS: A prospective cohort included men and women older than 50 years at the time of a FF. FRAX scores without bone mineral density [FRAX-body mass index (BMI)] were calculated prior to and after the inclusion FF. Recurrent FFs were recorded over a 4-year follow-up. Determinants associated with recurrent FF were determined by univariate and multivariate analyses. RESULTS: FRAX-BMI scores were available in 1399 of the 1409 recruited patients. A high-risk FRAX-BMI score was present in only 42.7% patients before and 56.4% after the incident FF. Most FF patients at low or moderate risk before their initial FF were men, younger than 65 years, or without previous FF. Over a median follow-up of 3 years, recurrent FF occurred in 108 patients (2.69 per 100 patient-years). The overall sensitivity of post-FF FRAX to predict a recurrent FF was 71.3% and was specifically lower in patients younger than 65 years (13%) and without previous FF (63%) at inclusion. CONCLUSIONS: The FRAX-BMI scores were below the Canadian threshold for treatment in more than half the patients at the time of a FF and in close to a third of patients with recurrent FF. FRAX-BMI severely underestimates the FF risk in patients younger than 65 years old and after a single FF.

Atypical fracture of the tibial diaphysis associated with bisphosphonate therapy: a case report.

Atypical subtrochanteric femoral shaft fractures (AFFs) have recently emerged as a potential long-term complication of bisphosphonate therapy. In 2010, the American Society for Bone and Mineral Research (ASBMR) Task Force published a definition for AFF consisting of 5 major and 7 minor features. Little attention has so far been paid to the possibility that bisphosphonate-associated atypical fractures may also involve the diaphysis of other long bones. We report here the case of a patient on long-term bisphosphonate therapy who presented a diaphyseal tibial insufficiency fracture fulfilling all the major criteria (except for the location), and a number of the minor criteria of an atypical fracture. Our case report suggests the need for greater awareness of the possibility of atypical fractures at other sites, particularly in weight-bearing long bones other than the femur, and suggests that long-term bisphosphonate therapy may also contribute to the occurrence of these atypical fractures.