Microcomputed analysis of nerve angioarchitecture after combined stem cell delivery and surgical angiogenesis to nerve allograft.

INTRODUCTION: A detailed three-dimensional (3D) evaluation of microvasculature is evolving to be a powerful tool, providing mechanistic understanding of angiomodulating strategies. The aim of this study was to evaluate the microvascular architecture of nerve allografts after combined stem cell delivery and surgical angiogenesis in a rat sciatic nerve defect model. MATERIALS AND METHODS: In 25 Lewis rats, sciatic nerve gaps were repaired with (i) autografts, (ii) allografts, (iii) allografts wrapped in a pedicled superficial inferior epigastric artery fascia (SIEF) flap to provide surgical angiogenesis, combined with (iv) undifferentiated mesenchymal stem cells (MSC) and (v) MSCs differentiated into Schwann cell-like cells. At two weeks, vascular volume was measured using microcomputed tomography, and percentage and volume of vessels at different diameters were evaluated and compared with controls. RESULTS: The vascular volume was significantly greatest in allografts treated with undifferentiated MSCs and surgical angiogenesis combined as compared to all experimental groups (P<0.01 as compared to autografts, P<0.0001 to allografts, and P<0.05 to SIEF and SIEF combined with differentiated MSCs, respectively). Volume and diameters of vessel segments in nerve allografts were enhanced by surgical angiogenesis. These distributions were further improved when surgical angiogenesis was combined with stem cells, with greatest increase found when combined with undifferentiated MSCs. CONCLUSIONS: The interaction between vascularity and stem cells remains complex, however, this study provides some insight into its synergistic mechanisms. The combination of surgical angiogenesis with undifferentiated MSCs specifically, results in the greatest increase in revascularization, size of vessels, and stimulation of vessels to reach the middle longitudinal third of the nerve allograft.

Intra-luminal gene therapy in the porcine artery using a recombinant adeno-associated virus 9.

The ability to improve or restore blood flow and promote healing in ischemic tissue has many potential clinical applications. Augmentation by direct delivery of growth factors may further enhance results, but requires a method for sustained delivery. In this study, we have tested the ability of adeno-associated virus 9 (AAV9) delivered within the lumen of a porcine artery to transfect the vessel and produce a desired product. The marker chosen was green fluorescent protein (GFP) (Ke et al., 2011). In 4 farm pigs the cranial tibial artery was surgically exposed. The vessel was temporarily clamped proximally, and divided distally. A cannula was placed intraluminally, and the arterial segment was injected with 1×10E13 particles of AAV9.CB7.CI.GFP·WPRE.rBG. At 14days the transfected cranial tibial artery as well as the liver, spleen and kidneys were harvested. ELISA and reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) were used to analyze the artery for GFP production. Significant GFP expression was seen in all transfected cranial tibial vessels, as determined by both GFP protein production (ELISA) and mRNA (RT-qPCR). No GFP was identified in liver, spleen or kidney, nor in the no-GFP control animal artery. Adeno-associated virus 9 is an appropriate vector for gene therapy experiments in the porcine artery model. This vector, and the intraluminal deliver method described result in robust gene expression at 2weeks without evident systemic spill of the virus. The ability to limit delivery of the gene to an isolated segment of vessel is desirable for future research applications.

The outcome and complications of vascularised fibular grafts.

AIMS: Free vascularised fibular grafting has been used for the treatment of large bony defects for more than 40 years. However, there is little information about the risk factors for failure and whether newer locking techniques of fixation improve the rates of union. The purpose of this study was to compare the rates of union of free fibular grafts fixed with locking and traditional techniques, and to quantify the risk factors for nonunion and failure. PATIENTS AND METHODS: A retrospective review involved 134 consecutive procedures over a period of 20 years. Of these, 25 were excluded leaving 109 patients in the study. There were 66 men and 43 women, with a mean age of 33 years (5 to 78). Most (62) were performed for oncological indications, and the most common site (52) was the lower limb. Rate of union was estimated using the Kaplan-Meier method and risk factors for nonunion were assessed using Cox regression. All patients were followed up for at least one year. RESULTS: The rate of union was 82% at two years and 97% at five years. Union was achieved after the initial procedure in 76 patients (70%) at a mean of ten months (3 to 19), and overall union was achieved in 99 patients (91%). No surgical factor, including the use of locked fixation or supplementary corticocancellous bone grafts increased the rate of union. A history of smoking was significantly associated with a risk of nonunion. DISCUSSION: Free vascularised fibular grafting is a successful form of treatment for large bony defects. These results suggest that the use of modern techniques of fixation does not affect the risk of nonunion when compared with traditional forms of fixation, and smoking increases the risk of nonunion following this procedure. Cite this article: Bone Joint J 2017;99-B:134-8.

The arterial anatomy of the medial femoral condyle and its clinical implications.

The success of vascularized bone grafts from the medial femoral condyle in various clinical applications has sparked renewed interest in the microvascular anatomy of this region. This study describes the arterial supply of the distal medial femoral condyle and its implications in harvesting vascularized bone grafts. The location, branching pattern, internal diameter, and distribution of perforators of the descending genicular artery and superior medial genicular artery in 19 fresh cadaveric lower limbs were recorded. The descending genicular artery was present in 89% and the superior medial genicular artery was present in 100% of specimens with average distances proximal to the articular surface of 13.7 cm and 5.2 cm, respectively. The average number of perforating vessels was greatest in the posterior distal quadrant of the condyle. The blood supply of the medial femoral condyle is plentiful and consistent making it a useful source for free vascularized bone grafts.

[Healing of free vascularized bone allotransplants: optimizing by short-term immunosuppression and host-derived neovascularization]. / Einheilung vaskularisierter Knochenallotransplantate : Optimierung durch Kurzzeit-Immunsuppression und der empfängerbasierten Neovaskularisation.

BACKGROUND: Living bone allotransplants (ATs) currently require long-term immunosuppression (IS), but this is impractical for extremity-preserving procedures. An alternative method to maintain viability of the transplant uses host-derived neoangiogeneic vessels combined with short-term IS. MATERIALS AND METHODS: Diaphyseal femoral defects in Dutch-Belted rabbits were reconstructed with a free microvascular AT from New Zealand White rabbits. Additionally, a host-derived intramedullary pedicled fascial flap was placed and short-term IS administered to two of four groups. Neovascularization and bone healing were quantified by microangiography and a custom radiographic score. RESULTS: Bone ATs with perfused fascial flaps achieved bone healing equivalent to autotransplant controls, even when they received IS only until host-derived neoangiogenesis replaced the original perfusion. Vascularized ATs without this combination achieved significantly inferior results. SUMMARY: This rabbit model demonstrated that increased bone turnover allows good healing but may temporarily weaken the allotransplant. However, by the more intense replacement of the graft with host-derived cells, this process may, in the long-term, ultimately result in a better transplant than an avascular graft.

Treatment of isolated injuries of the lunotriquetral ligament. A comparison of arthrodesis, ligament reconstruction and ligament repair.

We studied 57 patients with isolated lunotriquetral injuries treated by arthrodesis, direct ligament repair, or ligament reconstruction. The outcomes were compared by using written questionnaires, the Disabilities of the Arm, Shoulder and Hand (DASH) score, range of movement, strength, morbidity and rates of reoperation. Isolated lunotriquetral injury was confirmed by arthroscopy or arthrotomy. The mean age of the patients was 30.7 years (15.4 to 53.7) and the injuries were subacute or chronic in 98.2%. Eight patients underwent lunotriquetral reconstruction using a distally-based strip of the tendon of extensor carpi ulnaris, 27 had lunotriquetral repair and 22 had lunotriquetral arthrodesis. The mean follow-up was 9.5 years (2 to 22). The probability of remaining free from complications at five years was 68.6% for reconstruction, 13.5% for repair, and less than 1% for arthrodesis. Of the lunotriquetral arthrodeses, 40.9% developed nonunion and 22.7% developed ulnocarpal impaction. The probability of not requiring further surgery at five years was 68.6% for reconstruction, 23.3% for repair and 21.8% for arthrodesis. The DASH scores for each group were not significantly different. Objective improvements in strength and movement, subjective indicators of pain relief and satisfaction were significantly higher in the lunotriquetral repair and reconstruction groups than in those undergoing arthrodesis.

Vascularized bone grafts for scaphoid nonunions and kienböck's disease.

Vascularized bone grafts offer the ability to transfer bone with viable osteoclasts and osteoblasts with a preserved circulation. The resultant primary bone healing without creeping substitution through necrotic bone is an attractive alternative to conventional bone grafting in aiding or accelerating healing, replacing deficient bone, and revascularizing necrotic bone. Recent advances in the anatomy and physiology of vascularized bone grafts have increased the understanding and ability to apply them to various of carpal maladies. This article focuses on the principles, anatomy, application, and experimental and clinical studies of vascularized bone grafts for the treatment of scaphoid nonunions and Kienböck's disease.

Vascular anatomy of the distal radius: implications for vascularized bone grafts.

The vascular anatomy of the distal radius and ulna is complex with a series of longitudinal vessels anastomosing with a series of arches. This complex anastomotic network of vessels has a consistent spatial relationship to surrounding anatomic structures and is constant in nature. Knowledge of the vascular anatomy of the distal radius and ulna has allowed the creation of numerous reverse flow pedicled vascularized bone grafts, which can be applied to carpal pathologic features to assist in the healing of difficult fractures or avascular necrosis. The anatomy and terminology of the vascular network and the implications, indications, and applications of this anatomy to carpal pathologic features is reviewed.

A vascularized bone graft for repair of scaphoid nonunion.

The majority of scaphoid fractures respond to casting, splinting, or open reduction and internal fixation. In patients who fail to heal a scaphoid fracture, several factors may contribute, including delay in treatment, fracture displacement, proximal third location, avascular necrosis, and associated carpal instability.

[Possible applications of pedicled vascularized bone transplants of the distal radius]. / Anwendungsmöglichkeiten gestielter vaskularisierter Knochentransplantate vom distalen Radius.

Reverse-flow pedicle vascularized bone grafts (VBGs) from the distal radius may be used for the surgical treatment of carpal fracture nonunions and avascular necrosis. Such grafts remain viable with quantifiable blood flow as demonstrated in a recent canine experiment. In this paper, the vascular anatomy of the distal radius is demonstrated and the surgical technique of VBG harvest is described. Our indications and results for treatment of scaphoid nonunion and Kienböck's disease are discussed and compared with the current literature. Fifteen patients with scaphoid nonunion and nine patients with Kienböck's disease stage IIIa were treated by reverse-flow pedicled VBG. Range of motion and grip strength were measured postoperatively and compared to the contralateral hand in all patients. An outcome questionnaire was used to measure patient's satisfaction and ADL's in the patients with Kienböck's disease. The radiologic diagnostic was performed with conventional X-rays, trispiral tomograms and MRI. In the scaphoid nonunion group, all patients were male, with an average age of 27.6 years. Five patients had prior attempts of autogenous bone grafting which failed. Six patients had a radiographic suggestion of proximal fragment avascular necrosis. All scaphoids healed. Time to union was 11.1 weeks on average. Average follow-up was 36.2 months. Pain relief, range of motion and grip strength were very promising. The treatment of Kienböck's disease was also promising in nine patients. Mean patient age was 31 years, and follow-up averaged 32 months. Six patients had complete pain relief, and three had occasional pain. Grip strength reached 86% of the contralateral side (a 25% improvement from preoperative values). Postoperative MRI demonstrated progressive revascularization with time. The results of treating scaphoid nonunions are promising. The use of vascularized bone graft facilitates rapid, reliable union of established scaphoid nonunion, even with proximal location and/or avascular changes. Clinical results in Kienböck's disease have been gratifying as well, with MRI evidence of gradual revascularization on follow-up studies.

Role of conventional and vascularized bone grafts in scaphoid nonunion with avascular necrosis: A canine experimental study.

The effectiveness of vascularized and conventional bone grafts in the treatment of carpal fracture nonunion with avascular necrosis was evaluated in 12 adult dogs. The proximal third of the radiocarpal bone was removed bilaterally and frozen in liquid nitrogen. Its replacement, leaving a 4-mm gap, simulated a scaphoid fracture nonunion with avascular necrosis. A dorsal radius inlay graft was placed across the gap. The graft was nonvascularized, or conventional on one side, and vascularized with a reverse-flow arteriovenous pedicle on the other. Following a healing period, quantitative assessment of bone blood flow, fracture healing, and bone remodeling was conducted. Seventy-three percent of the vascularized grafts and none of the conventional grafts healed. At 6 weeks, bone blood flow in the proximal pole was significantly higher on the side of the vascularized graft. Quantitative histomorphometry of the avascular proximal segment demonstrated significantly higher levels of fluorochrome-labeled osteoid- and osteoblast-covered trabecular surfaces on the vascularized graft side. These experimental data support the potential clinical application of pedicled reverse-flow vascularized grafts in the treatment of carpal fracture nonunions with avascular necrosis, including proximal pole scaphoid nonunions.

Chronic anconeus compartment syndrome: A case report.

Compartment syndrome of the forearm is commonly associated with the volar compartment. We present a case of compartment syndrome of the anconeus muscle. Release of the anconeus muscle fascia provided relief of symptoms.

Diagnosis and management of hamate hook fractures.

Hamate hook fractures, although uncommon, are now recognized with increasing frequency because of the increase in popularity of racket sports and golf. Careful clinical evaluation and adjunctive radiologic investigation help establish the diagnosis. Acute nondisplaced fractures can heal with immobilization, while displaced fractures and nonunions typically require open reduction and internal fixation (acute fractures) or hook excision.

Lunotriquetral instability: diagnosis and treatment.

Isolated injury of the lunotriquetral interosseous ligament complex and associated structures is less common and is poorly understood compared with the other proximal-row ligament injury, scapholunate dissociation. The spectrum of injuries ranges from isolated partial tears to frank dislocation, and from dynamic to static carpal instability. The diagnosis may be difficult to establish because of the many possible causes of ulnar-sided wrist pain and the often normal radiographic appearance. The mechanism of injury is variable and includes attrition by age, positive ulnar variance, and perilunate or reverse perilunate injury. Appropriate treatment requires assessment of the degree of instability and the chronicity of the injury. Options include corticosteroid injection, immobilization, ligament repair, ligament reconstruction with tendon grafts, limited intercarpal arthrodesis, and ulnar shortening.

Free tissue transfer in the treatment of linear scleroderma.

Linear scleroderma is a subtype of localized scleroderma that most commonly affects children. The disease is rare, and the course is unpredictable. Most cases spontaneously resolve in 3-5 years. A small number, however, slowly progress to involve deeper subcutaneous tissues, muscles, and periosteum. Subsequent joint contractures and gross disturbances are frequent. Little on treatment is recorded in the literature. We report on four children who, in addition to bony procedures and release of joint and ligamentous contractures, had excision of the diseased skin and free soft-tissue transfer for coverage.

Experimental carpal reverse-flow pedicle vascularized bone grafts. Part I: the anatomical basis of vascularized pedicle bone grafts based on the canine distal radius and ulna.

We investigated the detailed extraosseous and intraosseous vascular anatomy of the distal radius and ulna in 55 pairs of canine forelimbs. Ten specimens were used for compartment identification. One hundred specimens were investigated after intra-arterial injection with red latex or Batson's compound. The extraosseous vascular network, including the nutrient artery location, was studied by delicate dissection and soft tissue digestion. Two superficial and 4 deep arteries were found on the dorsal aspect, with constant relationships to the retinaculum. On the palmar aspect, bony nutrient vessels rose from the branches of the radial artery (descriptive anatomy). The vascular supply of the canine distal forelimb was very consistent and enabled the design of 5 vascularized pedicle bone grafts similar to those described in humans (applied anatomy). These reverse-flow pedicle grafts may be placed in the carpus, allowing the canine forelimb to serve as an experimental model for the study of vascularized carpal bone grafting. (J Hand Surg 2000; 25A:34-45.

Experimental carpal reverse-flow pedicle vascularized bone grafts. Part II: bone blood flow measurement by radioactive-labeled microspheres in a canine model.

Reverse-flow pedicle vascularized bone grafts (VBGs) from the radius, commonly used for carpal nonunion and avascular necrosis, provide superior clinical results. In this experimental study bone blood flow in canine distal radius VBGs was measured to determine the status of the bone circulation immediately after elevation (group 1) and 2 weeks later (group 2). Immediate VBG flow (group 1) was substantial, but significantly less than the contralateral undisturbed distal radius (8.42 mL/min/100 g and 16.53 mL/min/100 g, respectively). At 2 weeks after surgery (group 2) VBG flow was compared with nonvascularized control grafts. Vascularized bone graft flow was significantly higher than group 1 (mean, 33.72 mL/min/100 g). Minimal flow was seen in the conventional graft control (0.62 mL/min/100 g). This study demonstrates that reverse-flow pedicle radius VBG maintain enhanced bone circulation long-term. Given the similarity of human and canine distal radius vascular anatomy, these data support the clinical use of reverse-flow VBG for carpal pathology. (J Hand Surg 2000; 25A:46-54.

Extensor triggering in de Quervain's stenosing tenosynovitis.

Extensor triggering is an uncommon but recognized component of de Quervain's stenosing tenosynovitis. In a retrospective review of 827 patients with the diagnosis of de Quervain's disease over a 5-year period, 11 patients with 13 affected wrists were identified who had demonstrable triggering by both history and physical examination (prevalence of 1.3%). One wrist underwent surgical release without conservative treatment. The remaining 12 wrists were initially treated with nonoperative modalities. Failure of conservative treatment as defined by recurrent triggering and pain occurred in 7 wrists, of which 5 underwent surgical release. At the time of surgery, all wrists were noted to have synovitis, separate compartments for the extensor pollicis brevis and abductor pollicis longus tendons, and no intratendinous nodules. After an average follow-up period of 42 months (range, 5.7-94.5 months) there were no recurrences of triggering after surgical treatment. Seven of 12 wrists with triggering de Quervain's stenosing tenosynovitis failed nonoperative treatment. Triggering or locking in extension is an uncommon symptom in de Quervain's stenosing tenosynovitis and demonstrates a more recalcitrant course when treated nonoperatively.

Dynamic axial carpal instability: a case report.

The concept of distal carpal row dissociation is not new. It has occurred secondary to high-energy crush or blast injuries, with resultant axial dislocations of both carpal rows and metacarpals. Axial carpal sprains without disruption or dynamic axial carpal instability have not been previously described. The evaluation of this new type of carpal instability with radiographs, tomography, arthrography, and magnetic resonance imaging failed to demonstrate its etiology. Arthroscopic evaluation of the midcarpal and radiocarpal joints demonstrated a dynamic axial carpal instability with incompetence of the capitohamate and scapholunate ligaments. Stabilization of the axial instability by capitohamate arthrodesis relieved the chronic wrist pain.