Treatment of Freiberg's disease using a reverse pedicled metatarsal bone flap: Case report.

Despite no surgical procedures receiving unanimous support for treating Freiberg's disease, several surgical treatment options have been described. For the past few years, bone flaps have been shown in children to present promising regenerative properties. We report a novel technique using a reverse pedicled metatarsal bone flap from the first metatarsal to treat one case of Freiberg's disease in a 13-year-old female. The patient presented 100% involvement of the second metatarsal head, with a 6 × 2 mm defect, unresponsive to 16 months of conservative measures. A 7 mm × 3 mm pedicled metatarsal bone flap (PMBF) was obtained from the lateral proximal first metatarsal metaphysis, mobilized and pedicled distally. It was inserted at the dorsum of the distal metaphysis of the second metacarpal towards the center of the metatarsal head, reaching the subchondral bone. Initial favorable clinical and radiological results were maintained for over 36 months during the last follow-up. Based on the powerful vasculogenic and osteogenic properties of bone flaps, this novel technique could effectively induce bone revascularization and prevent further collapse of the metatarsal's head.

Maternal allogeneic cancellous bone graft for the treatment of osteitis along the physeal scar of the proximal metatarsus in a foal.

OBJECTIVE: To describe the treatment and outcome of a foal with a fresh allogenic cancellous bone graft after surgical debridement of a traumatic septic osteitis. ANIMAL: A neonatal Quarter Horse foal. STUDY DESIGN: Case report. METHODS: The foal sustained a traumatic laceration exposing the proximal third metatarsal bone. One week after surgical debridement and closure, radiographic signs of septic osteitis were noted along the physeal scar. The lesion was debrided, and antimicrobial therapy was implemented. The infection resolved but left a large defect in the metaphysis and epiphysis. Grafting was indicated to avoid pathologic fractures of the plantar and proximal cortices. Due to a discrepancy between defect size and the bone stock of the foal, an allogeneic cancellous bone graft was harvested from the dam's tuber coxae and used to fill the foal's defect. RESULTS: No adverse reactions to the graft were noted. After 1 month, the wound had healed. Radiographic examination was consistent with graft incorporation in the bone structure. The foal was sound at a walk and trot when examined at 6, 12, and 21 months. The bone's contour was even and its structure homogeneously radio dense. The surgical site of the mare healed without complications. CONCLUSION: Fresh allogenic cancellous bone grafting resulted in the healing of a large traumatic-septic bone defect in a foal, with an excellent functional and cosmetic outcome. For future use, compatibility testing should be considered prior to allogeneic bone grafting.

Does metatarsus primus elevatus really exist in hallux rigidus? A weightbearing CT case-control study.

BACKGROUND: Elevated first metatarsal, Metatarsus primus elevatus (MPE), has been a topic of controversy. Recent studies have supported a significantly elevated first metatarsal in hallux rigidus on weight-bearing radiographs (WBR). However, conventional radiographs have limitations for accurate measurement. Our objective was to comparatively assess MPE and other variables which can affect the spatial relationship of the forefoot in the HR group compared to controls using weight-bearing CT (WBCT). METHODS: In this single-center, retrospective, case-control study, 25 patients (30 feet) with symptomatic HR and 30 controls were selected. WBCT parameters were measured by two independent investigators. Inter-observer reliabilities were assessed using intra-class correlation coefficients (ICCs). MPE was evaluated by measuring the direct distance between 1st and 2nd metatarsals. Independent t tests were performed to compare the two groups. A threshold of MPE to diagnose HR was calculated using the Receiver Operating Characteristic (ROC) curve. RESULTS: HR groups had increased hallux valgus angle (HVA) (8.52° in control vs 11.98° in HR) and MPE (2.92 vs 5.09 mm), decreased 1st metatarsal declination angle (21.09° vs 19.07°) 1st/2nd metatarsal declination ratio (87.45 vs 79.71) indicating elevated first metatarsal compared to controls. Dorsal translation of the first metatarsal at the first tarsometatarsal joint was observed in 21 (70%) patients of the HR group when defined as a step-off or discontinuation of the curvature along the first TMT joint. The threshold of MPE for diagnosis of HR was 4.19 mm with 77% sensitivity and 77% specificity. CONCLUSION: Our results confirmed a significantly elevated first metatarsal in the HR group compared to controls on WBCT. A MPE greater than 4.19 mm was found to be diagnostic for symptomatic HR. Significant number of patients in the HR group (70%) had dorsal translation of the first metatarsal at the first TMT joint which can contribute to increased MPE. CLINICAL RELEVANCE: The present study demonstrated significantly increased MPE in HR on WBCT and MPE greater than 4.19 mm on WBCT can be used as a diagnostic threshold for HR.

Acute, isolated fractures of the metatarsal bones: an epidemiologic study.

INTRODUCTION: Although metatarsal fractures are common, the significance of previous epidemiologic studies is limited to specific fracture entities, subpopulations, or heterogeneous fracture aetiologies. The aim of the study was to assess the epidemiology of isolated metatarsal fractures in an adult population at a level-1 trauma centre. MATERIALS AND METHODS: Radiological and clinical databases were searched for a five-year period. Eligible were all patients with acute isolated metatarsal fractures over the age of 18 years with radiographs in two planes available. Stress fractures, injuries affecting Lisfranc joint stability, and concomitant injuries to other regions than the metatarsals were excluded. Data collection included general demographics, mechanism of injury, season of the trauma and fracture details. RESULTS: Out of 3259 patients, 642 patients met the inclusion criteria and were included for the analysis. The patients' mean age was 44.5 ± 18.9 years, 50.6% were female. 83.3% suffered an isolated, 16.7% multiple metatarsal fractures. Single metatarsal fractures occurred predominantly at the fifth metatarsal bone (81.3%), their frequency decreased with increasing age, with a seasonal peak during the summer. Patients suffering multiple metatarsal fractures were significantly older (51.6 ± 21.2 vs. 43.0 ± 18.1 years; p < 0.001) and the injury resulted significantly more often from a high-energy trauma (6.7% vs. 23.4%; p < 0.001). Multiple metatarsal fractures occurred evenly throughout all metatarsals but revealed a focus on female population with no seasonal differences. CONCLUSION: Single metatarsal fractures predominantly occurred at the fifth metatarsal bone and showed a seasonal, gender and age dependency. Multiple metatarsal fractures were homogeneously distributed between the different metatarsals with distinct age-dependent gender differences. LEVEL OF EVIDENCE: Level III.

Contrast administration via ultrasound-guided injection of the cranial tibial artery results in contrast enhancement of the soft tissues of the metatarsus in horses undergoing CT.

Delivery of mesenchymal stem cells (MSC) via intravascular techniques to treat diffuse and/or inaccessible soft tissue injuries has grown in popularity. The purpose of the current prospective, analytical pilot study was to utilize CT to validate this novel technique and provide additional evidence to support its use for injectate delivery to specific soft tissue structures. Of particular interest was the proximal suspensory ligament, which presents a challenging injection target. Six adult horses without lameness underwent CT of the distal hindlimbs. Scans were obtained prior to ultrasound-guided catheterization of the cranial tibial artery, in addition to early and delayed scans acquired following intra-arterial contrast administration. Region of interest analysis of the superficial and deep digital flexor tendons and suspensory ligament was used to assess contrast enhancement within these structures. Linear mixed models were used to determine statistical significance. Significant (P < 0.05) mean contrast enhancement was seen in all postinjection time points in all soft tissue structures of interest. This indicates that ultrasound-guided injection of the cranial tibial artery results in perfusion of injectate throughout the distal hind limb, including the major soft tissue structures of the metatarsus. This provides further support for this technique as a method of MSC delivery to multifocal or inaccessible injury of these structures, including the proximal suspensory ligament.

Brachymetatarsia: A Classification for Surgical Treatment.

Brachymetatarsia is a congenital osseous and soft tissue deformity of a ray(s) of the foot. Because there is no particular consensus of methodology of lengthening for brachymetatarsia, the authors introduce a comprehensive anatomic classification and a surgical guide to treatment of each classification type. This classification combines the number of the metatarsal(s) affected and the letter(s) indicating the type of brachymetatarsia deformity (A = axial deficiency of the metatarsal, B = bowing of the metatarsal, C = congruency of metatarsal phalangeal joint). This study reviewed of 300 brachymetatarsals in 166 patients. Fifty of the 166 (30%) patients had bilateral brachymetatarsia. Of the 300 metatarsals with brachymetatarsia, 64 (21%) were first metatarsals, 22 (7%) were second metatarsals, 28 (9%) were third metatarsals, 12 (4%) were fifth metatarsals, and 174 (58%) were fourth metatarsals. Classification types that were found was a total of 165 (55%) type A, a total of 6 (2%) type B, a total of 72 (24%) type AB, a total of 39 (13%) type AC, and a total of 18 (6%) type ABC. A total of 16 (10%) male and 150 (90%) female patients were evaluated. The mean preoperative amount of shortening of the metatarsal was 15 mm (range, 4-20 mm), as determined by the preoperative metatarsal parabola deficiency, equating to 30% of the preoperative metatarsal length. Brachymetatarsia is a complex congenital deformity which until now has not been critically analyzed. This study outlines a comprehensive brachymetatarsia classification system which provides an accurate diagnosis of the deformity and offers a surgical treatment algorithm.

A comparative analysis of clinical, functional and radiographic outcomes of patients with and without fusion between the first and second metatarsals after the lapidus procedure.

BACKGROUND: The aim of this study was to compare the clinical, functional and radiographic outcomes in patients who underwent the original Lapidus procedure (OLP) with fusion and undesired non-fusion between the first (M1) and second (M2) metatarsals. METHODS: A retrospective and comparative analysis of 29 patients (38 feet) who underwent the OLP was performed. They were divided in two groups: (1) 23 feet in which fusion occurred and (2) 15 with undesired non-fusion. Clinical and functional data were assessed with the VAS for pain, AOFAS, LEFS and SF-12. SF-12 comprises physical and mental health scales (PCS-12 and MCS-12). Radiographic parameters assessed were bony and soft tissue forefoot widths (BSFW), intermetatarsal-angle (IMA) and HV-angle (HVA). RESULTS: Separately, the groups presented significant improvements in all questionnaires (p < 0.001), except on MCS-12 (fusion p = 0.08 and non-fusion p = 0.27). When comparing both groups, patients with fusion had higher AOFAS scores (p < 0.05). Both groups presented the same improvements on BSFW, IMA and HVA (p = 0.09, p = 0.16, p = 0.52 and p = 0.63). CONCLUSION: Excellent results were observed, even when without fusion between M1 and M2. Patients who evolved with fusion between the M1 and M2 showed greater improvements in the AOFAS score. LEVEL OF EVIDENCE: III, retrospective comparative study.

Freiberg`s disease of lesser metatarsals treated with bone grafting and autologous matrix induced chondrogenesis (AMIC) membrane - A series of 10 cases.

BACKGROUND: Freiberg's infraction is osteonecrosis of lesser metatarsal heads most commonly affecting adolescent females. They usually present with pain and swelling of the forefoot. MRI is useful investigation in the early diagnosis. It is a self-limiting disease and the main stay of treatment is non operative. Surgery is indicated in failed conservative management which include open debridement, cheilectomy, micro fracture, osteotomies and excision arthroplasty with varying success. METHODS: A retrospective analysis of ten patients with Freiberg`s disease of the lesser metatarsals treated with open debridement, microfracture, bone grafting and application of AMIC (Autologous Matrix induced Chondroplasty) membrane was carried out. The patients were followed up to five years and the outcome measures were scored using Manchester-Oxford Foot Questionnaire (MOxFQ) and EQVAS best health scores. RESULTS: The mean age was 42.7 years and follow-up time was 36.4 months. The most common site was second metatarsal, eight (80%) followed by third metatarsal, two (20%). The mean base line MOxFQ was 72.5 (95% CI- 45 ± 100) which improved to 42.5 (95%CI- 2.5 ± 82.5) at one year. The mean baseline VAS improved from 26.4(10.2 ± 42.6) to 30.3 (95%CI- 2.1 ± 58.5) at one year. The mean MOxFQ and VAS at the end of 36 months was 31.4(95%CI-6.6 ± 57.2) and47.3(4.3 ± 80.3) respectively. CONCLUSIONS: Open debridement of the Freiberg`s disease combined with microfracture of the defect, bone grafting and application of AMIC membrane shows reliable functional and radiological outcomes at short term follow up.

Metatarsal head restoration versus dorsal closing-wedge osteotomy in the treatment of advanced-stage Freiberg's disease.

PURPOSE: Freiberg's disease is mostly characterized by osteonecrosis of second metatarsal head and is widely seen in adolescent women. Metatarsal head restoration technique is a novel surgical procedure intended to protect intact articular surface and regenerate avascular bone under cartilage. This study aimed to evaluate and compare the results and clinical outcomes of metatarsal head restoration technique with those of dorsal closing-wedge osteotomy technique in patients with advanced-stage Freiberg's disease. METHODS: In this retrospective study, 60 patients who were operated for Freiberg's disease were evaluated. Patients were divided into two groups as who underwent metatarsal head restoration and dorsal closing-wedge osteotomy. Groups were compared according to "American Orthopaedic Foot & Ankle Society score" (AOFAS), "visual analog score" (VAS) and passive "range of motion" (ROM) score. RESULTS: Thirty-two feet of 29 patients underwent metatarsal head restoration, while 33 feet of 31 patients were subject to dorsal closing-wedge osteotomy. Mean AOFAS score increased from 58.72 ± 6.89 to 89.35 ± 7.43 following metatarsal head restoration, while it increased from 54.13 ± 6.12 to 78.24 ± 6.54 after dorsal closing-wedge osteotomy. Mean VAS score decreased from 6.89 ± 1.18 to 1.33 ± 0.64 after metatarsal head restoration, while it decreased from 6.64 ± 0.92 to 2.71 ± 1.91 following dorsal closing-wedge osteotomy. Mean ROM increased from 12.25° ± 1.65 to 56.28° ± 2.77 after metatarsal head restoration, and it increased from 11.18° ± 0.66 to 47.65° ± 2.05 after dorsal closing-wedge osteotomy (all p < 0.05). In addition, postoperative mean AOFAS (p = 0.044), VAS (p = 0.041) and passive ROM (p = 0.034) scores improvement were found to be statistically significantly better in the metatarsal head restoration group. CONCLUSION: This study revealed that metatarsal head restoration is a safe and successful surgical technique. It leads to better results than dorsal closing-wedge osteotomy in patients with stages 3-4 Freiberg's disease. LEVEL OF EVIDENCE: III.

Shortening effect influence of Distal Minimally Invasive Metatarsal Osteotomy in primary metatarsalgia.

PURPOSE: In primary metatarsalgia, Distal Minimally invasive Metatarsal Osteotomy (DMMO) achieves a correct load distribution which is a factor in pain relief, but contrary to the elevation of the metatarsal head, shortening the metatarsal length has no influence on plantar-loading parameters, while the increased metatarsal length is a factor in the development of metatarsalgia. Thus, we hypothesized that metatarsalgia could be partly related to a functional imbalance between bone structure and soft tissues and pain relief after DMMO results from soft tissue relaxation. METHODS: Many authors have highlighted the correlation between joint pressure and periarticular soft tissue tension. To test our hypothesis, we measured intra-operatively the MTPJ pressure of 19 patients suffering from primary metatarsalgia, before and after DMMO. This pressure is being analyzed as a reflection of joint decompression and forefoot soft tissue release. Many authors have highlighted the correlation between joint pressure and periarticular soft tissue tension. RESULTS: Lower metatarsals presenting metatarsalgia show a significantly lower MTPJ pressure compared to asymptomatic rays, and DMMO induces a significant increase of MTPJ pressure. CONCLUSION: Those variations reflect the functional imbalance between bone structure and soft tissue in primary metatarsalgia. The biomechanical rationale of the shortening effect of DMMO could therefore be explained by the release of forefoot soft tissue, which could take part in the pain relief by restoring this balance.

Arthroscopic removal of osteochondral fragments located within the condylar fossa of the third metacarpus/metatarsus in Thoroughbred yearlings.

OBJECTIVE: To describe an arthroscopic technique for the removal of osteochondral fragments located within the condylar fossa of the third metacarpal/tarsal bone. STUDY DESIGN: Retrospective study. ANIMALS: Thoroughbred yearlings (n = 11). METHODS: Osteochondral fragments located within the condylar fossa of the third metacarpal/tarsal bone identified during presale radiographic examination were removed via arthroscopy, assisted with ultrasonography in select cases. Complete fragment removal was confirmed by intraoperative radiography. RESULTS: Fragments were successfully removed using rongeurs following dissection of soft tissue attachments using a bipolar radiofrequency probe. No postoperative complications occurred. CONCLUSIONS: An ipsilateral arthroscopic and instrument portal coupled with ultrasound assistance and a radiofrequency probe allowed for successful removal of fragments located within the condylar fossa of the third metacarpal/tarsal bone. The technique allowed for the removal of the unstable osteochondral fragment and associated physical debris. CLINICAL SIGNIFICANCE: The described surgical technique enables the removal of osteochondral fragments located within the condylar fossa of the third metacarpal/tarsal bone with minimal disruption to the surrounding soft tissues.

Conservative Treatment for Metatarsus Adductus, A Systematic Review of Literature.

There are various treatment approaches for the subjects with metatarsus adductus, including nonsurgical and surgical treatment. Nonsurgical treatments such as serial casting, modified shoes (Bebax shoe, Ipos antiadductus shoe) and orthoses (Wheaton brace, counter rotation system splint, Denis Brown bar, and Fillauer bar) are widely used in this regard. The main question posted here is which orthoses are more effective in correcting metatarsus adductus. Therefore, the aim of this review was to determine the efficiency of various nonsurgical treatments used for metatarsus adductus. MEDLINE/PubMed, EMBASE, Cochrane Central Register of Controlled Trial, Cochrane Data base of systematic review (CDSR), Scopus and ISI Web of knowledge (from 1960 to 2021) were searched by predefined search strategies to screen eligible randomized controlled studies meeting established criteria. The quality of the studies was assessed based on Down and Black tool. 200 studies on this topic were reviewed and finally 11 studies which met the inclusion criteria were selected for final analysis. These studies evaluated the efficiency of nonsurgical treatment options on foot angle and deformity correction in the subjects with metatarsus adductus. Quality of the papers based on Downs and Black tool varied between 13 and 23. Some treatments such as Wheaton brace, rigid strap, exercise (manipulation), reverse last shoe and plaster cast are used for these subjects. Although good correction can be achieved with use of these treatment methods, some of them have complications which should be considered in this regard. It seems that Wheaton brace and Bebax shoe have fewer complications compared to other methods.

Description of a Revision Technique for Failed Polyvinyl Alcohol Hydrogel Implant in Patient with Freiberg's Disease.

Polyvinyl alcohol hydrogel synthetic cartilage implants are increasingly used to treat advanced Freiberg disease. We report a case with recurrence of symptoms within 6 weeks and required revision for fracture of the implant. We describe a revision technique with modified osteochondral bone graft to deal with the variables of revision surgery namely: the bone loss, collateral ligament insufficiency, and changes to the proximal phalanx articular surface. We describe a postoperative plan, recovery and a good outcome achieved in 12 month follow-up.

Evaluation of Radiographic Features Including Metatarsus Primus Elevatus in Hallux Rigidus.

The etiology of hallux rigidus remains a controversial issue in foot and ankle surgery, i.e., the relationship between metatarsus primus elevatus (MPE) and hallux rigidus. The purpose of this study was to evaluate several radiographic parameters including first metatarsal elevation in patients with hallux rigidus compared to a matched control group. A retrospective case control study was performed including 50 feet, 25 feet with and 25 feet without hallux rigidus. In the patients with hallux rigidus, the first metatarsal was more elevated than in the control group (8.3 ± 1.7 mm vs 3.0 ± 2.0 mm, p < .001) and in 60% of patients with hallux rigidus MPE was diagnosed, compared to zero patients in the control group (p < .001). The lateral 1 to 2 intermetatarsal angle was higher in patients with hallux rigidus (3.6 ± 2.5 vs -0.7 ± 2.8; p < .001). The first metatarsal declination angle was not different between the 2 groups. Intraclass correlation coefficient between 2 observers for measuring the first metatarsal elevation was 0.929 (p < .001). In the current study, increased elevation of the first metatarsal, a higher incidence of MPE and increased lateral 1 to 2 intermetatarsal angle were found in patients with hallux rigidus compared to the control group. These findings support the theory of an association between MPE and hallux rigidus. Further high reliability of first metatarsal elevation measurement was found in our study.

Risks of injury in distal metatarsal minimally invasive osteotomy when comparing standard and modified techniques: A cadaveric study.

BACKGROUND: The objectives of the study were to evaluate the structures at risk in distal metatarsal mini-invasive osteotomy (DMMO) and to compare standard and intraosseous approaches. METHODS: DMMO was performed on the second and fourth metatarsals of 11 fresh-frozen cadaveric specimens. The standard technique was performed in 11 metatarsals. It was then compared to a modified intraosseous technique that entails starting inside the bone in 11 other metatarsals. The cadavers were dissected to identify unintentional injury to soft tissue structures. RESULTS: In the standard group the most injured structures were the metatarsal joint capsules (MJC) (27%), extensor digitorum longus (EDL) (18%), and extensor digitorum brevis (EDB) (9%). The modified intraosseous group injured the EDL (27%), not the MJC (0%) and the EDB (0%). Distances between osteotomies and the dorsal metatarsal head articular surface (DMHAS) were 6.08 ± 3.99 mm in the standard and 9.92 ± 3.42 mm in the modified (p = 0.02). CONCLUSION: The DMMO techniques most frequently injured the EDL. Intra-articular positioning of the osteotomy was more observed in the standard. Overall, it appears the modified method could be an alternative to the standard DMMO. CLINICAL RELEVANCE: The modified minimally invasive DMMO has a comparable rate of potential iatrogenic injuries. This intraosseous procedure may present as an option when planning surgery to the lesser metatarsals. LEVEL OF EVIDENCE: Level III. Comparative Cadaveric Study.

Fibular and metatarsal osteosynthesis in a southern brown howler monkey (Alouatta guariba clamitans).

Here we describe a successful surgical management of a distal fibular fracture combined with a tarsocrural luxation and multiple metatarsal fractures in the left foot of a southern brown howler monkey (Alouatta guariba clamitans). We achieved satisfactory outcome by applying intramedullary pinning for each of the bone fractures and closed reduction of joint luxation-kept in place only by bone alignment, without further ligament reconstruction. Bone healing occurred uneventfully within eight weeks and the monkey's foot regained its normal function. Therefore, we could properly release the patient back into the wild.

A Systematic Approach to the Surgical Correction of Combined Hallux Valgus and Metatarsus Adductus Deformities.

The presence of metatarsus adductus (MTA) adds complexity to the diagnosis and treatment of hallux valgus (HV). Identification and careful analysis of these combined deformities is of paramount importance. The inability to completely correct HV and an increased incidence of recurrence has been established when MTA deformity is present. We present an option for correction of the combined deformities with multiplanar angular correction arthrodesis of the first, second, and third tarsometatarsal (TMT) joints.

Surgical interventions of Freiberg's disease: A systematic review.

BACKGROUND: Freiberg's disease is an osteonecrosis of the metatarsal head bone. Numerous surgical interventions can be provided; however, the literature is limited in systematic reviews discussing the various options. The study aimed to systematically review the quantity and quality of literatures exploring the surgical interventions. METHODS: Fifty articles were found to be relevant for assessing the efficacy of common surgical interventions. The articles were assigned a level of evidence (I-V) to assess their quality. Next, the studies were reviewed to provide a grade of recommendation (A-C, I). RESULTS: Two studies were found at level III that explored osteotomy and autologous transplantation; the other studies were level IV-V. There is poor evidence (grade C) in supporting of joint sparing and joint sacrificing for Freiberg's disease. CONCLUSION: Poor evidence exists to support the surgical interventions for Freiberg's disease, higher quality trials are needed to support the increasing application of these surgical techniques. LEVEL OF EVIDENCE: Level IV, Systematic review.

Distribution and development of the external sense organ pattern on the appendages of postembryonic and adult stages of the spider Parasteatoda tepidariorum.

Spiders are equipped with a large number of innervated cuticular specializations, which respond to various sensory stimuli. The physiological function of mechanosensory organs has been analysed in great detail in some model spider species (e.g. Cupiennius salei); however, much less is known about the distribution and function of chemosensory organs. Furthermore, our knowledge on how the sense organ pattern develops on the spider appendages is limited. Here we analyse the development of the pattern and distribution of six different external mechano- and chemosensory organs in all postembryonic stages and in adult male and female spiders of the species Parasteatoda tepidariorum. We show that except for small mechanosensory setae, external sense organs appear in fixed positions on the pedipalps and first walking legs, arranged in longitudinal rows along the proximal-distal axis or in invariable positions relative to morphological landmarks (joints, distal tarsal tip). A comparison to other Entelegynae spiders shows that these features are conserved. We hope that this study lays the foundation for future molecular analysis to address the question how this conserved pattern is generated.

Cell engraftment, vascularization, and inflammation after treatment of equine distal limb wounds with endothelial colony forming cells encapsulated within hydrogel microspheres.

BACKGROUND: Endothelial colony forming cells (ECFCs) may be useful therapeutically in conditions with poor blood supply, such as distal limb wounds in the horse. Encapsulation of ECFCs into injectable hydrogel microspheres may ensure cell survival and cell localization to improve neovascularization and healing. Autologous ECFCs were isolated from 6 horses, labeled with quantum nanodots (QD), and a subset were encapsulated in poly(ethylene) glycol fibrinogen microspheres (PEG-Fb MS). Full-thickness dermal wounds were created on each distal limb and injected with empty PEG-Fb MS, serum, ECFCs, or ECFCs encapsulated into PEG- Fb MS (ECFC/MS). Analysis included wound surface area (WSA), granulation tissue scoring (GS), thermography, collagen density staining, and immunohistochemical staining for endothelial and inflammatory cells. The purpose of this study was to track cell location and evaluate wound vascularization and inflammatory response after injection of ECFC/MS or naked ECFCs in equine distal limb wounds. RESULTS: ECFCs were found near and within newly formed blood vessels up to 3 weeks after injection. ECFC and ECFC/MS groups had the greatest blood vessel quantity at week 1 in the wound periphery. Wounds treated with ECFCs and ECFC/MS had the lowest density of neutrophils and macrophages at week 4. There were no significant effects of ECFC or ECFC/MS treatment on other measured parameters. CONCLUSIONS: Injection of microsphere encapsulated ECFCs was practical for clinical use and well-tolerated. The positive ECFC treatment effects on blood vessel density and wound inflammation warrant further investigation.