Yasunori Kobata

Experimental study of vascularized tissue-engineered bone grafts.

Background: Vascularized bone grafting has become a useful method for treatment of large bone defects and infected nonunions that lack adequate blood supply. This method has disadvantages, however, such as donor-site complications. To overcome these disadvantages, the authors developed a new method for creating vascularized tissue-engineered bone grafts in an experimental model. Methods: Fisher rat bone marrow mesenchymal stem cells were cultured for 2 weeks in fully opened, interconnected, porous hydroxyapatite ceramic. The composites of mesenchymal stem cells and hydroxyapatite were implanted in the medial calf region together with the saphenous vascular bundle in syngeneic rats. Two weeks after implantation, the vascular pedicle with the implants was exposed and covered with silicone rubber to prevent vascular invasion through surrounding tissues (vascularized mesenchymal stem cell/hydroxyapatite implants). In addition, nonvascularized mesenchymal stem cell/hydroxyapatite implants were created with a ligated vascular pedicle. Implants of vascularized hydroxyapatite alone were prepared as a control. All implants were retrieved 4 weeks after surgery. Results: Histologically, de novo bone formations were observed in the vascularized implants. This was in contrast with only necrotic tissue observed in the nonvascularized implants. Bone formation was not observed entirely in the vascularized hydroxyapatite-alone implants. For biochemical analysis, alkaline phosphatase activity and osteocalcin content of the vascularized mesenchymal stem cell/hydroxyapatite implants were significantly higher than those of the nonvascularized mesenchymal stem cell/hydroxyapatite and vascularized hydroxyapatite-alone implants. Conclusion: The results of this study indicated that the vascularized tissue-engineered bone grafts could be transferred as free vascularized grafts to lesions that lack adequate blood supply.

Indications for free vascularized fibular grafting for the treatment of osteonecrosis of the femoral head

BackgroundThe present study aimed to determine the indications for free vascularized fibular grafting for the treatment of osteonecrosis of the femoral head.MethodsSeventy-one hips (60 patients) were clinically followed for a minimum of 3 years. Average follow-up period was 7 years. Etiologies were alcohol abuse in 31 hips, steroid use in 27, idiopathic in 7 and trauma in 6. Preoperative staging of the necrotic lesion was done using the Steinbergs classification system. The outcomes of free vascularized fibular grafting were determined clinically using the Harris hip-scoring system, radiographically by determining progression, and survivorship by lack of conversion to total hip replacement.ResultsThe average preoperative Harris hip score was 56 points and the average score at the latest follow-up examination was 78 points. Forty-seven hips (67%) were clinically rated good to excellent, 4 hips (6%) were rated fair, and 20 hips (28%) were rated poor. Thirty-six hips (51%) did not show radiographic progression while 35 hips (49%) did, and with an overall survivorship of 83% at 7 years. Steroid-induced osteonecrosis was significantly associated with poor scores and survival rate (68%). Preoperative collapse was significantly associated with poor scores, radiographic progression and poor survival rate (72%). A large extent of osteonecrosis greater than 300 degrees was significantly associated with poor scores, radiographic progression and poor survival rate (67%). There was no relationship between the distance from the tip of the grafted fibula to the subchondral bone of the femoral head and postoperative radiographic progression.ConclusionIn conclusion, small osteonecrosis (less than 300 degrees of the femoral head) without preoperative collapse (Steinbergs stages I and II) is the major indication for free vascularized fibular grafting. Steroid-induced osteonecrosis is a relative contraindication. Large osteonecrosis (greater than 300 degrees) with severe preoperative collapse (greater than 3 mm) is a major contraindication. Hips with 2 negative factors such as severe preoperative collapse and a large extent of osteonecrosis, require hip replacements.

Anatomy of Y-shaped configurations in the subscapular arterial system and clinical application to harvesting flow-through flaps.

Background: A flow-through flap is useful in cases where the recipient artery must not be sacrificed. The aim of this study was to investigate Y-shaped configurations in the subscapular arterial system that can safely be used in harvesting a flow-through flap from the scapular region. Methods: Sixteen dissections of the subscapular arterial system were carried out in eight embalmed cadavers. The origins and external diameters of branches in the subscapular arterial system were recorded. The distances between the origins of each branch were measured. Results: The branches that showed a consistent presence and had a reliable diameter of more than 1.0 mm were the circumflex scapular artery, the bony branch of the circumflex scapular artery, the thoracodorsal artery, the angular branch, and branches to the serratus anterior and latissimus dorsi muscles. It was demonstrated that using the Y-shaped configuration between these branches enables the harvesting of a flow-through flap in various length versions of the Y-shaped vascular pedicles. A significant anatomical variation (i.e., both the thoracodorsal and circumflex scapular artery arose directly from the axillary artery) was found in three of 16 dissections. In this vascular variation, sacrificing the axillary artery must be avoided, so Y-shaped pedicles using the origin of the thoracodorsal or circumflex scapular artery cannot be created. On the basis of these results, flow-through flaps using this arterial system were applied in 10 patients for reconstruction of lower extremities, and satisfactory results were obtained. Conclusions: The results of our study are available for determining preoperatively and intraoperatively which Y-shaped configuration to use in harvesting a flow-through flap from the scapular region.

Oberlin partial ulnar nerve transfer for restoration in obstetric brachial plexus palsy of a newborn: case report

An 8 month old male infant with Erbs birth palsy was treated with two peripheral nerve transfers. Except for rapid motor reinnervations, elbow flexion was obtained by an Oberlins partial ulnar nerve transfer, while shoulder abduction was restored by an accessory-to-suprascapular nerve transfer. The initial contraction of the biceps muscle occurred two months after surgery. Forty months after surgery, elbow flexion reached M5 without functional loss of the ulnar nerve. This case demonstrates an excellent result of an Oberlins nerve transfer for restoration of flexion of the elbow joint in Erbs birth palsy. However, at this time partial ulnar nerve transfer for Erbs birth palsy is an optional procedure; a larger number of cases will need to be studied for it to be widely accepted as a standard procedure for Erbs palsy at birth.

Long-term follow-up of periarterial sympathectomy for chronic digital ischaemia

This study investigates long-term clinical results (> 10 years) of periarterial sympathectomy in chronic ischaemic digits compared with intermediate-term results (3 years). Periarterial sympathectomy via the palm and volar wrist was carried out on 11 hands of seven patients with digital ischaemia but no gangrene or severe ulceration. The aetiology of ischaemia was Buerger’s disease in four hands, collagen disease in three hands, and repetitive digital trauma in four hands. Subjective symptoms were evaluated at a mean follow-up period of 12 years. The efficacy of surgery was assessed objectively using thermography and plethysmography. Although five of seven patients continued on oral vasodilators and antiplatelet agents until the final follow-up, improvement of symptoms was maintained in all patients between intermediate- and long-term evaluations. Our results suggest that periarterial sympathectomy via the palm and wrist could prevent long-term aggravation of symptoms of chronic digital ischaemia when combined with adequate postoperative drug therapy.

Treatment of Kienböck disease in an 11-year-old girl with temporary fixation of the scaphotrapeziotrapezoidal joint

An 11-year-old girl with Kienböck disease (stage IIIA) was treated by temporary scaphotrapeziotrapezoidal fixation. It was fixed in a cast for four weeks and wires removed after eight weeks. Follow up examinations showed that movement of the wrist and grip strength were improved, and she had no pain while revascularisation of the lunate could be seen on magnetic resonance imaging.

Pedicled Vascularized Bone Graft from the Medial Supracondylar Region of the Femur for Treatment of Femur Nonunion

A free vascularized bone graft harvested from the supracondylar region of the femur was used to treat patients with nonunion but without a massive bone defect. This graft is vascularized by the descending genicular artery (DGA). In patients with femur nonunion, pedicled vascularized bone grafts are usable in some cases. To confirm the applicable range of this graft, we performed dissection of the DGAs in 16 lower limbs of eight embalmed cadavers. A pedicled bone graft from the supracondylar region of the femur was harvested and rotated proximally to the femur as far as possible. The distance from the apex of the medial epicondyle to the central point of the transferred bone (DMEB) was measured. DMEBs ranged from 13.0 to 20.0 cm (mean, 17.3). Dividing the DMEB by femoral length we defined as the transposition ratio. Transposition ratios ranged from 0.48 to 0.70 (mean, 0.60). These results showed we could transfer enough graft to a distal half of the femur. This technique has a good indication for intractable nonunion without significant bone defects of the distal half of the femur where conventional techniques are not practical.

Advanced Kienböck's disease treated with implantation of a tendon roll and temporary partial fixation of the wrist.

Twenty‐one patients with advanced Kienböcks disease were treated by implantation of a tendon roll and temporary partial fixation of the wrist. There were 13 women and eight men. Their ages at the time of operation ranged from 24 to 72 years. According to Alexander and Lichtmans classification, 12 patients were stage IIIb and nine stage IV. After implantation of the tendon roll, the scaphotrapezio‐trapezoidal joint was fixed with Kirschner wires in 19 patients, and the scaphocapitate joint with absorbable pins in two. Postoperative wrist pain disappeared in nine patients and was reduced in 12. The mean postoperative total arc of flexion and extension of the wrist increased from 91° to 103°, and mean grip strength improved from 11.5 to 17.2 kg. Loosening of Kirschner wires during partial fixation of the wrist was seen in six cases, and required early removal of the loose wires.

Radiocarpal arthrodesis for osteoarthritis following fractures of the distal radius.

To compare the radioscapholunate (RSL) arthrodesis and radiolunate (RL) arthrodesis as a treatment for radiocarpal osteoarthritis following fractures of the distal radius, nine patients, 23 to 70 years old (average 41) at the time of surgery, were assessed two to 33 years after surgery. The periods between injury and surgery ranged from four months to 30 years. RSL arthrodesis was performed in three cases and RL arthrodesis in six. Post-operative wrist pain disappeared in six and was decreased in the other three. In the RSL group, the total arc of wrist flexion and extension was reduced from 50 degrees pre-operatively to 35 degrees post-operatively. In the RL group, it was increased from 72 degrees to 76 degrees after surgery. Grip strength improved in most patients, from 7 to 18 kg in the RSL group, and from 16 to 27 kg in the RL group. On roentogenogram, three patients showed arthritic changes in the adjacent joints, but there were no symptoms in two of the three patients. We concluded that partial radiocarpal arthrodesis (preferably RL arthrodesis) is a reliable procedure for radiocarpal osteoarthritis following fractures of the distal radius.

Osteogenesis of cryopreserved osteogenic matrix cell sheets

Cryopreservation of tissue engineered bone (TEB), whilst maintaining its osteogenic ability, is imperative for large-scale clinical application. We previously reported a novel cell transplantation method, in which bone-marrow-derived mesenchymal stem cells (BMSCs) were cultured to confluence and differentiated down the osteogenic lineage to form osteogenic matrix cell sheets (OMCS). OMCS have high alkaline phosphatase (ALP) activity and osteocalcin (OC) contents and can be easily used for producing TEB. The aim of the present study was to investigate whether TEB produced by cryopreserved OMCS maintains sufficient osteogenic potential in vivo. OMCS were prepared and divided into three groups according to storage period of cryopreservation (fresh (no cryopreservation), 4 week and 12 week cryopreservation groups). OMCS were cryopreserved by storage in freezing medium (Cell Banker 1®) at -80 °C. Cryopreserved OMCSs were rapidly thawed at room temperature and wrapped around Hydroxyapatite (HA) scaffolds prior to implantation into subcutaneous sites in rats, to determine their in vivo bone-forming capability. The constructs were harvested 4 weeks after transplantation and examined histologically and biochemically. Histological analysis of the constructs showed extensive bone formation in the HA pores with high ALP activity and OC content detected in the cryopreservation groups. The present study clearly indicates that cryopreserved/thawed OMCS are still capable of producing mineralized matrix on scaffolds, resulting in bone formation. This cryopreservation technique could be applied for hard tissue reconstruction to ease the cell preparation method prior to time of use.