Kepler Alencar Mendes de Carvalho

A critical limitation common to all minimally invasive surgery (MIS) approaches is the lack of direct visualization during osteotomy execution, which exposes arteries, nerves, and tendon insertions to iatrogenic injury within a confined anatomical space. This review synthesizes applied anatomical knowledge relevant to third- and fourth-generation MIS for hallux valgus (HV), incorporating findings from cadaveric dissection and micro-computed tomography (CT) vascular mapping to characterize the tendinous, neural, vascular, and sesamoid architecture of the first metatarsal head complex and to define quantitative safety zones for intraoperative reference. Micro- CT perfusion studies have established that the apex of the Chevron osteotomy should be positioned at a minimum distance of 25.6 mm (dorsal arm) and 23.9 mm (plantar arm) from the most distal point of the first metatarsal articular surface, with the excursion of the Shannon burr limited to 3.9 mm and 4.0 mm beyond the exit point on the lateral cortex. The Metaphyseal Extra-Articular Transverse and Akin Osteotomy (META) technique introduces a geometrically distinct risk profile by simultaneously addressing the dorsal and plantar metatarsal arteries in a single transverse plane; for this technique, a unified safety distance of approximately 26 mm is proposed for the osteotomy, pending specific anatomical application and micro-CT validation. Neurological risk for both osteotomy generations centers on the dorsomedial nerve of the first toe. Biomechanical and radiographic equivalence between third- and fourth generation constructs indicates that the choice of technique should be guided by surgical training rather than perceived mechanical superiority, and that safe execution depends on mastering the anatomical boundaries described in this review. Level of Evidence V; Expert Opinion, Basic Science Study

Introduction: O hálux valgo (HV) é um desvio lateral doloroso do hálux e desvio medial do primeiro metatarso do pé, que afeta quase 20% da população em geral. Uma cirurgia minimamente invasiva pode corrigir a deformidade utilizando parafusos canulados ou fios de Kirschner. Este estudo avaliou a eficácia e a segurança dos dois métodos de fixação com um acompanhamento de dois anos. Métodos: Este foi um ensaio clínico planejado, aberto e paralelo, conduzido em um único hospital ortopédico, com um modelo de superioridade. Randomizamos 40 pacientes adultos com hálux valgo moderado a grave para serem operados utilizando fios de Kirschner ou parafusos canulados para fixação. Os pacientes alocados ao grupo dos fios de Kirschner retornaram em seis semanas para a remoção dos fios (o que impediu o mascaramento). Avaliamos a função e a correção radiográfica do hálux valgo como projetos primários e, secundariamente, para satisfação, alterações degenerativas em dois anos e efeitos adversos. Resultados: De 2021 a 2022, 64 pacientes foram internados para cirurgia de HV e 40 foram randomizados. Perdemos 6 pacientes durante o acompanhamento, 3 em cada grupo. Todos os resultados radiográficos apresentaram melhora ao longo do tempo, sem diferença significativa entre os grupos. As desempenho de função e dor também melhoraram, com desempenho de função mais elevadas no grupo de fios de Kirschner aos 6, 12 e 24 meses (p < 0,001). Não houve degeneração relevante aos 24 meses. Dos 7 Conclusão: Não foram encontradas diferenças importantes entre os dois implantes em relação aos resultados clínicos, radiográficos, de segurança, funcionais e degenerativos tardios. PALAVRAS CHAVE: Hallux valgus; Parafusos ósseos; Fios ortopédicos K-wires; Cannulated screws. KEYWORDS: Hallux valgus; Bone screws; Bone wires;

Background: Traditional methods of evaluating Hallux Valgus (HV) have limitations in assessing 3D deformity elements such as first metatarsal pronation and sesamoid subluxation. This study aimed to use coverage mapping (CM) to analyze surface interactions of the first metatarsophalangeal joint (MTPJ) and metatarsosesamoid joints in HV and control patients, correlating findings with visual analog scale (VAS) pain scores. We hypothesized that patients with HV would show decreased joint coverage, reflective of joint subluxation, and that these changes would correlate with higher VAS scores. Methods: A distance mapping (DM) algorithm was applied to weightbearing computed tomography (WBCT) images from 44 symptomatic HV patients and 43 controls. Color-coded CMs were obtained from these distance measurements and were divided into quadrants for analysis. Regions showing joint space widths t tests, Wilcoxon tests, and regression models. Results: CM revealed significant reductions in joint coverage in HV patients, particularly in specific quadrants of the first MTPJ and metatarsosesamoid joints. No association was found between CM features and VAS scores. Higher VAS scores were associated with younger age, lower MRA, and higher BMI. Conclusion: 3D WBCT CM revealed significant subluxation and deviation in HV patients. VAS scores were influenced by demographic variables and metatarsal rotation, but not CMs, suggesting unique challenges beyond subluxation and pain. WBCT mapping generates hypothesis-generating visualizations of HV deformity; prospective studies are required before it can guide diagnosis or surgical planning.

Resumo: O distúrbio clínico tradicionalmente conhecido como pé plano valgo por insuficiência do tendão tibial posterior ou pé plano valgo adquirido do adulto tem sido objeto de diversas publicações nas últimas duas décadas, e entende-se agora que o problema não está no tendão tibial posterior em si, pois o distúrbio pode ocorrer até mesmo sem a lesão desse tendão. Estudos trouxeram novos conceitos e entendimentos que questionaram o olhar sobre o tema, o que culminou na substituição das classificações existentes por uma que fosse mais assertiva e discriminativa dos possíveis padrões de apresentação da deformidade. Além disso, também propôs-se a mudança da nomenclatura para “deformidade colapsante progressiva do pé” (DCPP; progressive collapsing foot deformity, PCFD, em inglês).Quanto ao tratamento cirúrgico, ainda persiste o conceito de abordagem à la carte, com ênfase no realinhamento dos eixos, o que pode ser obtido por meio de osteotomias, artrodeses e equilíbrio de partes moles, que consiste em transposições/reparos tendinosos e reconstrução de estruturas ligamentares, sobretudo do complexo ligamentar deltoide e do ligamento mola.

Background: The diagnosis of syndesmotic instability is challenging, and chronically unstable injuries can potentially lead to ankle arthritic degeneration. The objective of this cadaveric study was to utilize a 3-dimensional (3D) weight-bearing computed tomography (WBCT) distance mapping algorithm for the detection of subtle syndesmotic instability, induced by complete syndesmotic ligament sectioning and stressed by isolated axial load. We hypothesized that this algorithm would accurately detect subtle syndesmotic instability. Methods: Nineteen matched pairs of through-the-knee cadaveric specimens (38 legs) were utilized. Specimens were mounted in a frame that allowed simulated axial weight-bearing (356 N). Specimens were scanned using cone-beam WBCT in the normal pre-injury state and after complete syndesmotic ligament sectioning. The deltoid ligament was kept intact, and no external rotational stress was applied. Syndesmotic incisura and lateral gutter distances were assessed and compared between pre-injury ipsilateral, contralateral, and injured states using a 3D WBCT distance mapping algorithm. The receiver operating characteristic (ROC) curve and area under the curve (AUC) were calculated for the comparison of syndesmotic distance measurements between injured specimens and controls. P values of <0.05 were considered significant. Results: Overall, significantly increased distances were observed in injured specimens when compared with controls, with average relative syndesmotic widening in injured specimens of 16.9% (p = 0.0003), 11.3% (p = 0.0015), 6.4% (p = 0.0027), and 2.9% (p = 0.037) at the first 1, 3, 5, and 10 cm (proximal to the apex of the distal tibial articular surface), respectively. Widening was more pronounced in the anterior aspect of the syndesmosis, where the diagnostic accuracy was found to be highest at the first 1 and 3 cm of the syndesmotic incisura, with AUC values ranging from 80.9% to 83.0% (p < 0.0001) and with threshold diagnostic values of relative syndesmotic widening as low as 0.43 mm. Conclusions: The newly proposed 3D WBCT distance mapping algorithm was able to accurately detect subtle syndesmotic instability in a cadaveric model of complete syndesmotic sectioning under isolated axial weight-bearing load. This algorithm needs to be further validated in patients with suspected traumatic syndesmotic instability. Clinical Relevance: This cadaveric study demonstrated high diagnostic accuracy of a 3D WBCT distance mapping algorithm to detect subtle syndesmotic instability when stressed with isolated axial loading and in the absence of deltoid injury. The future use of this algorithm in patients with suspected unilateral traumatic syndesmotic instability could hopefully optimize the diagnosis and treatment decision-making.

Background: Minimally invasive surgical (MIS) chevron-type osteotomy for hallux valgus (HV) treatment offers a surgical alternative to open surgery with minimal surgical dissection and a hypothetical decreased risk for soft tissue complications. The objectives of this study were to assess the incidence of injuries to the soft tissue envelope and to the blood supply of the first metatarsal head through gross dissection and, using micro–computed tomography (micro-CT), to identify the safe position to perform the MIS chevron-type osteotomy of the first metatarsal head based on the anatomical data. Methods: Twenty cadaveric specimens with HV were used for the study. Seven specimens were perfused with a low-viscosity radiopaque polymer preoperatively. All specimens underwent MIS chevron-type osteotomy executed using a 20 × 2-mm Shannon burr at the metatarsal neck’s flare. Anatomical dissection of all specimens was then performed to assess macroscopic injury to the first metatarsal head complex soft tissue structures and blood supply. The 7 specimens that were preinjected then underwent micro-CT assessment to assess the first metatarsal head blood supply. Results: Two soft tissue injuries in 2 cadavers were identified, including a 2-mm injury to the flexor hallucis brevis in one specimen and a 1-mm injury to the dorsomedial nerve. No arterial injuries were identified in either the gross dissection or micro-CT imaging. Micro-CT has pinpointed a secure location to complete the chevron-type osteotomy. We found that finalizing the dorsal arm of the MIS chevron-type osteotomy at a median distance of 25.6 mm, and the plantar arm at 23.9 mm from the most distal point of the first metatarsal head, ensured safety in the specimens we used. Conclusion: As tested in this cadaveric study on 20 specimens, the MIS chevron-type osteotomy procedure preserved the soft tissue envelope of the first metatarsal head complex and the blood supply of the first metatarsal head, with a low number of injuries. Completing the dorsal arm of the MIS chevron-type osteotomy at a median distance of 25.6 mm, and the plantar arm at 23.9 mm from the furthest point of the first metatarsal head, while ensuring the Shannon burr does not exceed 3.9 mm dorsolaterally and 4.0 mm plantar-laterally from the cortical bone exit point, appeared crucial to avoid vascular damage.

Background: The main goal of this study was to evaluate postoperative changes in the length of the first metatarsal (M1) and the proximal phalanx of the hallux (P1) after acellular dermal allograft interpositional arthroplasty (ADA-IPA). We hypothesized that there would be a shortening of the first ray at the first metatarsal, the proximal phalanx, or both. Methods: In this retrospective study, we assessed patients who underwent ADA-IPA between 2019 and 2022. On standing anteroposterior (AP) foot radiographs, we measured first metatarsal (M1), second metatarsal (M2), proximal phalanx (P1), and the entire hallux (HX) lengths. M1/M2 and P1/HX ratios were calculated. The first metatarsophalangeal joint space was calculated. All measurements were recorded preoperatively, at 6 weeks postoperatively, and at final follow-up. Results: The pilot study included 11 patients. At final follow-up, we found shortening of M1 and P1 in comparison to the preoperative length, as evidenced by lower M1/M2 (82.6 ± 2.3 vs 75.4 ± 5.1; P = .001) and P1/HX ratios (53.4 ± 2.3 vs 48.9 ± 7.9; P = .001). Follow-up length was negatively correlated with M1/M2 ( r = −0.76, P = .003). Conclusion: ADA-IPA might be associated with shortening of both first metatarsal and proximal phalanx, with the former showing progressive shortening.