Total Ankle Arthroplasty as a Correction Tool for Foot Deformities: Analyzing the Impact on Medial Column Alignment Adaptation Through Weightbearing Computed Tomography.

BACKGROUND: While weightbearing computed tomography (WBCT) has been instrumental in analyzing total ankle arthroplasty (TAA) positioning, there is a notable gap in the literature regarding adaptive changes in the foot's medial column after TAA. This study aims to bridge this gap by comparing preoperative and postoperative alignments of the foot's medial column and analyzing if a correlation exists between TAA coronal alignment correction and medial column alignment adaptation. METHODS: Sixty patients who underwent a lateral approach TAA for end-stage osteoarthritis (OA) between January 2021 and April 2023 were included in this retrospective study. Patients were divided into varus (n = 30) and valgus (n = 30) groups. Preoperative and postoperative WBCT scans were analyzed to measure medial column alignment. Statistical analysis evaluated alignment corrections and correlations. RESULTS: Both groups showed significant plantarflexion of the second tarsometatarsal (TMT) angle, with a median adaptation of -1 degree (IQR -3, 0; P < .01) in the valgus group and -1 degree (IQR -3, 0; P = .03) in the varus group. The varus group exhibited increased plantarflexion of the first TMT angle (median -1 degree, IQR -1, -2; P = .03). Both groups demonstrated increased adduction of the medial column. The talonavicular coverage angle adaptation averaged 7.2 ± 14 degrees (P < .01) in the valgus and 9 ± 12 degrees (P < .01) in the varus group. The talo-first metatarsal axial angle adaptation was 5 ± 13 degrees (P = .03) in the valgus group and 9.5 ± 15 degrees (P = .08) in the varus group. CONCLUSION: WBCT analysis revealed significant medial column adaptation post-TAA in varus and valgus alignments. However, no correlation was found between hindfoot correction and forefoot adaptation, making it challenging to predict the need for additional realignment surgeries. Future studies should explore the relationship between tibiotalar correction and medial column alignment to improve outcomes and the influence of total ankle design on medial column adaptation. LEVEL OF EVIDENCE: Level III, retrospective case control study.

Hallux valgus treatment by percutaneous scarf-like screwless osteotomy: surgical technique and medium-term outcomes.

BACKGROUND: Hallux valgus is a common condition. There is a consensus that distal metatarsal osteotomies have positive outcomes for the correction of mild-to-moderate deformities, and that proximal osteotomies are preferable for more severe ones. The well-known scarf osteotomy technique is considered powerful enough for both types of deformation and is described without internal fixation. We aimed to describe a new surgical technique for hallux valgus percutaneous scarf like osteotomy (PSLO) without internal fixation, and to report the medium-term radiological and clinical outcomes. HYPOTHESIS: A combination of a PSLO without internal fixation will lead to optimal results. PATIENTS AND METHODS: This retrospective case series reports on 126 cases involving 106 patients who underwent hallux valgus surgery with the PSLO technique +/- Akin, +/- lateral release. The osteotomy was stabilized by a bandage, and immediate weight bearing was allowed. The surgeries took place in 3 clinics in France from March 2016 to July 2017. RESULTS: All radiological parameters: hallux valgus angle (HVA), the 1-2 intermetatarsal angle (IMA) and the distal metatarsal articular angle (DMAA) showed statistically significant improvement. The mean preoperative HVA, IMA and DMAA were 27.7 °, 14.2 ° and 12.7 ° respectively. The mean postoperative HVA, IMA and DMAA were 8.23 °, 8.1 ° and 3.8 °, respectively. Clinically, 97% were satisfied or very satisfied with the results, 92% could wear "normal" shoes (45 days - 6 months), 99% returned to the same athletic activities after surgery (3-5 months), and the average time to return to work was 4 weeks (1 day - 51 days). DISCUSSION: The combination of scarf -like osteotomy and the percutaneous technique provide sufficient initial stabilization through the large horizontal area of contact between the fragments and the preservation of the attachment of the soft tissue. The lack of internal fixation significantly shortens the surgery time, cost, and reduces x-ray exposure without compromising the results. LEVEL OF EVIDENCE: III, retrospective comparative study.

COP9 signalosome subunit 7 from Arabidopsis interacts with and regulates the small subunit of ribonucleotide reductase (RNR2).

The COP9 Signalosome protein complex (CSN) is a pleiotropic regulator of plant development and contains eight-subunits. Six of these subunits contain the PCI motif which mediates specific protein interactions necessary for the integrity of the complex. COP9 complex subunit 7 (CSN7) contains an N-terminal PCI motif followed by a C-terminal extension which is also necessary for CSN function. A yeast-interaction trap assay identified the small subunit of ribonucelotide reductase (RNR2) from Arabidopsis as interacting with the C-terminal section of CSN7. This interaction was confirmed in planta by both bimolecular fluorescence complementation and immuoprecipitation assays with endogenous proteins. The subcellular localization of RNR2 was primarily nuclear in meristematic regions, and cytoplasmic in adult cells. RNR2 was constitutively nuclear in csn7 mutant seedlings, and was also primarily nuclear in wild type seedlings following exposure to UV-C. These two results correlate with constitutive expression of several DNA-damage response genes in csn7 mutants, and to increased tolerance of csn7 seedlings to UV-C treatment. We propose that the CSN is a negative regulator of RNR activity in Arabidopsis.

The Arabidopsis COP9 signalosome subunit 7 is a model PCI domain protein with subdomains involved in COP9 signalosome assembly.

The COP9 Signalosome (CSN) is a multiprotein complex that was originally identified in Arabidopsis thaliana as a negative regulator of photomorphogenesis and subsequently shown to be a general eukaryotic regulator of developmental signaling. The CSN plays various roles, but it has been most often implicated in regulating protein degradation pathways. Six of eight CSN subunits bear a sequence motif called PCI. Here, we report studies of subunit 7 (CSN7) from Arabidopsis, which contains such a motif. Our in vitro and structural results, based on 1.5 A crystallographic data, enable a definition of a PCI domain, built from helical bundle and winged helix subdomains. Using functional binding assays, we demonstrate that the PCI domain (residues 1 to 169) interacts with two other PCI proteins, CSN8 and CSN1. CSN7 interactions with CSN8 use both PCI subdomains. Furthermore, we show that a C-terminal tail outside of this PCI domain is responsible for association with the non-PCI subunit, CSN6. In vivo studies of transgenic plants revealed that the overexpressed CSN7 PCI domain does not assemble into the CSN, nor can it complement a null mutation of CSN7. However, a CSN7 clone that contains the PCI domain plus part of the CSN6 binding domain can complement the null mutation in terms of seedling viability and photomorphogenesis. These transgenic plants, though, are defective in adult growth, suggesting that the CSN7 C-terminal tail plays additional functional roles. Together, the findings have implications for CSN assembly and function, highlighting necessary interactions between subunits.