Browsing by Author "Vela, Omar"
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Item "Angle to Be Corrected" in Preoperative Evaluation for Hallux Valgus Surgery: Analysis of a New Angular Measurement.(Sage, 2016) Ortiz, Cristián; Wagner, Pablo; Vela, Omar; Fischman, Daniel; Cavada, Gabriel; Wagner, EmilioBACKGROUND: The most common methods for assessing severity of hallux valgus deformity and the effects of an operative procedure are the angular measurements in weightbearing radiographs, specifically the hallux valgus angle and intermetatarsal angle (IMA). Our objective was to analyze the interobserver variability in hallux valgus patients of a new angle called the "angle to be corrected" (ATC), and to compare its capacity to differentiate between different deformities against IMA. METHODS: We included 28 symptomatic hallux valgus patients with 48 weightbearing foot x-rays. Three trained observers measured the 1 to 2 IMA and the ATC. We then identified retrospectively 45 hallux valgus patients, which were divided into 3 operative technique groups having used the ATC as reference, and analyzed the capacity of the IMA to differentiate between them. RESULTS: The IMA average value was 13.6 degrees, and there was a significant difference between observer 3 and observer 1 (P = .001). The average value for the ATC was 8.9 degrees, and there was no difference between observers. Both angles showed a high intraclass correlation. Regarding the capacity to differentiate between operative technique groups, the ATC was different between the 3 operative technique groups analyzed, but the IMA showed differences only between 2. CONCLUSIONS: The ATC was at least as reliable as the intermetatarsal angle for hallux valgus angular measurements, showing a high intraclass correlation with no interobserver difference. It can be suggested that the ATC was better than the IMA to stratify hallux valgus patients when deciding between different operative treatments.Item Cost effectiveness of different techniques in hallux valgus surgery.(Elsevier, 2016) Wagner, Emilio; Ortiz, Cristián; Torres, Karen; Contesse, Ivan; Vela, Omar; Zanoll, DiegoBACKGROUND: Different surgical techniques are available to correct each type of Hallux Valgus (HV) deformity, and all present similar good results. No information is available relative to the cost of each technique compared to their individual success. OBJECTIVE: To determine the cost-effectiveness-ratio (CER) of five different techniques for HV. METHODS: We included 245HV surgeries performed in 179 patients. The severity was defined according to radiological parameters. For mild to moderate HV we included the Chevron, Modified-Scarf and Ludloff techniques; for severe HV: either Poscow-osteotomy or Lapidus-arthrodesis fixed with plates or screws. Weighted costs were estimated. CER was expressed in $US dollars per AOFAS-point. RESULTS: The lowest weighted cost was observed for the Chevron-group, and the highest weighted cost was observed in the Poscow-osteotomy and Lapidus-arthrodesis fixed with plate groups. The AOFAS-score improvement was higher in the Chevron and Modified-Scarf groups. The CER found for Chevron and Modified-Scarf techniques were significantly less than for Poscow and Lapidus-techniques. CONCLUSION: Cost-Effectiveness-Ratio was lower, and therefore better, in the groups with mild to moderate deformities operated with Chevron or Modified-Scarf techniques. In severe HV, the three techniques investigated presented similar CER. CER analysis is an additional factor that can be included in the decision making analysis in hallux valgus surgery. Level of Evidence Level IV, Retrospective Study.Item Interosseous membrane window size for tibialis posterior tendon transfer—Geometrical and MRI analysis(Elsevier, 2016) Wagner, Pablo; Ortiz, Cristián; Vela, Omar; Arias, Paul; Zanolli, Diego; Wagner, EmilioBACKGROUND: Tibialis posterior (TP) tendon transfer through the interosseous membrane is commonly performed in Charcot-Marie-Tooth disease. In order to avoid entrapment of this tendon, no clear recommendation relative to the interosseous membrane (IOM) incision size has been made. OBJECTIVE: Analyze the TP size at the transfer level and therefore determine the most adequate IOM window size to avoid muscle entrapment. METHODS: Eleven lower extremity magnetic resonances were analyzed. TP muscle measurements were made in axial views, obtaining the medial-lateral and antero-posterior diameter at various distances from the medial malleolus tip. The distance from the posterior to anterior compartment was also measured. These measurements were applied to a mathematical model to predict the IOM window size necessary to allow an ample TP passage in an oblique direction. RESULTS: The average tendon diameter (confidence-interval) at 15cm proximal to the medial malleolus tip was 19.47mm (17.47-21.48). The deep posterior compartment to anterior compartment distance was 10.97mm (9.03-12.90). Using a mathematical model, the estimated IOM window size ranges from 4.2 to 4.9cm. CONCLUSION: The IOM window size is of utmost importance in trans-membrane TP transfers, given that if equal or smaller than the transposed tendon oblique diameter, a high entrapment risk exists. A membrane window of 5cm or 2.5 times the size of the tendon diameter should be performed in order to theoretically diminish this complication.Item Role of a limited transarticular release in severe hallux valgus correction(American Orthopaedic Foot & Ankle Society by Sage, 2015) Wagner, Emilio; Ortiz, Cristián; Figueroa, Francisco; Vela, Omar; Wagner, Pablo; Gould, JohnBackground: Hallux valgus (HV) treatment is continuously evolving, and no definitive treatment can be recommended. Osteotomies are the main surgical choice for these deformities, but no clear role for soft tissue procedures is available. Objective: To perform a retrospective comparison of the radiographic and clinical outcomes of 2 groups of patients with severe HV operated with the same osteotomy technique but differing on the type of lateral release. Methods: Two groups of patients with symptomatic moderate to severe HV deformities were operated with the same proximal metatarsal osteotomy, which differed on the type of lateral release: group 1 had limited transarticular lateral capsule release (n = 62), and group 2 complete lateral release, including capsule, adductor tendon, and intermetatarsal (IM) ligament (n = 57). We recorded the American Orthopaedic Foot & Ankle Society (AOFAS) score, HV and IM angles, first metatarsal shortening, concomitant metatarsal shortening osteotomies (Weil), Akin osteotomies, and complications. Results: The postoperative AOFAS score in group 1 was similar to that of group 2. The HV and IM angles improved in both groups with no significant difference. The multivariate analysis showed no influence of any variable analyzed on HV or IM angle improvement. Regarding AOFAS score improvement, a limited lateral release was associated with a higher increase in AOFAS score (P = .019). Conclusion: No studies are available to identify which soft tissue structures are involved in HV deformities nor which have to be released, if any. A limited transarticular release can provide similar clinical and radiologic outcomes when compared with a classic open lateral release.