[Vascularized bone grafting from the volar distal radius for carpal bones reconstruction]

The Selective Histone Deacetylase Inhibitor MI192 Enhances the Osteogenic Differentiation Efficacy of Human Dental Pulp Stromal Cells

The use of human dental pulp stromal cells (hDPSCs) has gained increasing attention as an alternative stem cell source for bone tissue engineering. The modification of the cells' epigenetics has been found to play an important role in regulating differentiation, with the inhibition of histone deacetylases 3 (HDAC3) being linked to increased osteogenic differentiation. This study aimed to induce epigenetic reprogramming using the HDAC2 and 3 selective inhibitor, MI192 to promote hDPSCs osteogenic capacity for bone regeneration. MI192 treatment caused a time-dose-dependent change in hDPSC morphology and reduction in viability. Additionally, MI192 successfully augmented hDPSC epigenetic functionality, which resulted in increased histone acetylation and cell cycle arrest at the G₂/M phase. MI192 pre-treatment exhibited a dose-dependent effect on hDPSCs alkaline phosphatase activity. Quantitative PCR and In-Cell Western further demonstrated that MI192 pre-treatment significantly upregulated hDPSCs osteoblast-related gene and protein expression (alkaline phosphatase, bone morphogenic protein 2, type I collagen and osteocalcin) during osteogenic differentiation. Importantly, MI192 pre-treatment significantly increased hDPSCs extracellular matrix collagen production and mineralisation. As such, for the first time, our findings show that epigenetic reprogramming with the HDAC2 and 3 selective inhibitor MI192 accelerates the osteogenic differentiation of hDPSCs, demonstrating the considerable utility of this MSCs engineering approach for bone augmentation strategies.

Intramedullary Screw and Kirschner Wire Fixation for Unstable Scaphoid Nonunion

Surgical treatment of scaphoid nonunion is not always successful, often requiring stabilization and bone grafting to achieve healing. Even after intramedullary screw fixation, residual instability may still hinder union. The purpose of this study was to describe the addition of Kirschner wires (KWs) through the capitate and the lunate to supplement an intramedullary screw for temporary enhanced stability, possibly improving healing of unstable fractures. A case-control study reviewing 25 cases with addition of KWs and 19 controls was performed. Demographic and fracture information, time to diagnosis, and healing time were documented. We found no differences in population characteristics, fracture characteristics, or outcome measures between patients treated with this method and those treated with a screw alone. We had no complications related to the addition of KWs. Preoperative lunate type and scapholunate gapping was suggestive but not significantly associated with KW insertion. Addition of KWs is safe and may be considered in scaphoid nonunion in the presence of intraoperative suboptimal stability. Intraoperative stability may possibly be inferred by reviewing preoperative radiographs for signs of instability.

Bone Grafts for Scaphoid Nonunion: An Overview

The scaphoid is the most common fractured bone in the wrist. Despite adequate non-surgical treatment, around 10% to 15% of these fractures will not heal. Untreated scaphoid non-union can cause a scaphoid non-union advance collapse (SNAC), this is a progressive deformity and can cause degenerative changes in the wrist. Surgery is focused on achieving consolidation, pain reduction and a good position of the scaphoid while preventing osteoarthritis in the long-term. Surgery consists of reduction and fixation of the scaphoid with a non-vascularized or vascularized bone graft. An overview of the most used vascularized and non-vascularized bone grafts and their indications are presented.

Dorsal vascularized grafting for scaphoid nonunion: a comparison of two surgical techniques

OBJECTIVES

To compare the radiographic and functional outcomes of 2 surgical techniques for treating scaphoid nonunion.

DESIGN

Randomized prospective study.

PATIENTS/PARTICIPANTS

Researchers assessed the outcomes every 2 weeks until bone healing and at discharge.

INTERVENTIONS

(1) Vascularized bone grafting (VBG) using the 1, 2 intercompartmental suprareticular artery and (2) a distal radius nonvascularized bone graft.

MAIN OUTCOMES/INTERVENTIONS

Time to union (primary), union rate, and functional outcomes.

RESULTS

Seventy-five patients were followed for 29 months; 2 were lost to final follow-up. Both groups had similar baseline characteristics. The VBG group reached bone union earlier by 12 days (P = 0.002), but union rates were similar (P = 0.312). There was also less ulnar deviation in the VBG group (P = 0.03). There were no other differences between either intervention groups.

CONCLUSIONS

Although the VBG group attained earlier union, this may not be clinically meaningful, nor justify the greater technical difficulty and use of resources associated with this intervention.

LEVEL OF EVIDENCE

Therapeutic Level II. See instructions for authors for a complete description of levels of evidence.

[Results of treatment of scaphoid nonunion with microvascularized bone grafts of the 1, 2 intercompartmental supraretinacular artery and osteosynthesis]

OBJECTIVE

To analyze the results of treatment of scaphoid nonunion with questionable viability of the proximal fragment, but without significant deformity or collapse, using a vascularized bone graft of 1,2 intercompartmental supraretinacular artery (1.2 ICSRA) and subsequent osteosynthesis.

MATERIAL AND METHOD

A retrospective study was performed on 10 male patients with a radiographic diagnosis of nonunion. Functionality, pain using Visual Analog Score (VAS), grip strength, patient satisfaction and reintroduction to working life, using QuickDASH and May specific wrist scales were assessed after the treatment. The integration of the graft was checked by radiography.

RESULTS

The mean follow-up was 31.4 months, and 90% of the questionnaires were satisfactory. The VAS decreased by 4.6 points and the flexor-extensor mobility gain was 5°. The total graft consolidation rate reached 40% in 5.5 months on average.

DISCUSSION

Several studies have demonstrated better results using vascularized bone graft versus non-vascularized. From the description by Zaidemberg in 1991, the vascularized graft with 1.2 ICSRA artery, distal radius, has been the most widely used for the treatment of scaphoid nonunion.

CONCLUSIONS

Our results are comparable with the literature reviewed, thus using vascular graft of the 1.2 ICSRA and osteosynthesis with Herbert-type screw, may be an alternative treatment for proximal scaphoid nonunion, without collapse or significant deformity.

Treatment of Avascular Necrosis of the Proximal Pole of the Scaphoid by Arthroscopic Resection and Prosthetic Semireplacement Arthroplasty Using the Pyrocarbon Adaptive Proximal Scaphoid Implant (APSI): Long-Term Functional Outcomes

Fractures of the proximal pole of the scaphoid with associated avascular necrosis and nonunion are well known to be problematic. Many techniques for fixation and reconstruction of the proximal pole of the scaphoid have been reported, often with poor results. One of the newer modalities of treatment for these difficult cases is excision of the proximal pole and replacement with a pyrocarbon implant. The ovoid shape of the implant acts as a spacer and repositions itself throughout the range of motion of the wrist. The procedure can be performed arthroscopically, thus reducing the morbidity and allowing the procedure to be a day case. Satisfactory results have been reported in elderly patients, but there is a paucity of literature regarding the outcomes in younger patients. This multicenter retrospective study evaluates the clinical, radiologic, and functional outcomes in patients under the age of 65 years with a minimum follow up of 5 years. There were 14 patients with scaphoid nonunion advanced collapse (SNAC) grade I, II, or III wrists, with a mean age of 53 years and mean follow up of 8.7 years. There were improvements in all of the patient related variables including VAS pain scores (7.5 to 0.7), extension (45° to 60°), flexion (32° to 53°), and grip strength (15.8 to 34.6 kg). Complications included volar subluxation of the implant, which was acutely surgically corrected (1), volar subluxation of the implant, with persistent pain that required a four-corner fusion (2), and secondary radial styloidectomy (3). This technique is an attractive, minimally invasive alternative for nonunion and avascular necrosis resulting from fractures of the proximal pole of the scaphoid. The authors provide details of the technique, including technical suggestions for performing the procedure.

Unstable scaphoid nonunion treatment technique: use of a volar distal radius corticocancellous autograft

Scaphoid nonunions are challenging cases that first must be identified and then treated based on stability, collapse, and vascularity. Unstable nonunions are identified on the basis of collapse of the scaphoid into the "humpback" deformity with an increased intrascaphoid and scapholunate angles. The importance of restoring normal scaphoid alignment has been stressed, because failure to do so leads to worse clinical and radiographic results with predictable patterns of radiocarpal arthrosis. We present a technique to correct unstable scaphoid nonunions using a single volar-based incision with harvesting of volar distal radius corticocancellous autograft. This technique allows the avoidance of harvest site morbidity and has union rates comparable with the gold standard of iliac crest.