Large and retracted rotator cuff tendon tears fail to repair, or re-tear following surgical intervention. This study attempted to develop novel tissue engineering approaches using tenocytes-seeded bioscaffolds for tendon reconstruction of massive rotator cuff tendon defect in rabbits. Porcine small intestine submucosa (Restore™) and type I/III collagen bioscaffold (ACI-MaixTM) were chosen as bioscaffold carriers for autologous tenocytes. Biological characterization of autologous tenocytes was conducted prior to the implantation. The tenocyte-seeded bioscaffolds were implanted as interposition grafts to reconstruct massive rotator cuff tendon defects in rabbits. In situ re-implantation of the autologous rotator cuff tendon, excised during defect creation served as a positive control. Histological outcomes were analysed and semi-quantitatively graded at four and eight weeks after surgery.

The results demonstrate that at four weeks both tenocyte-seeded bioscaffolds display inflammatory reaction similar to bioscaffold-only cuff reconstruction and the histological grading were inferior to control repair. However, at eight weeks inflammatory reaction of both tenocyte-seeded bioscaffolds were dramatically reduced as compared to bioscaffold alone. In addition, bioscaf-folds seeded with tenocytes generated similar histological appearance to that of the positive control.

The implantation of autologous tenocytes on collagen-based bioscaffold offers improved rotator cuff tendon healing and remodelling compared to the implantation of bioscaffold alone.

Spinal fusion surgery is a common procedure for the treatment of various spinal diseases. Several growth factors, including bone morphogenic protein-2 (BMP-2) and osteogenic protein-1 (OP-1) have been used in spinal fusion for the induction of bone formation. But complications have been reported due to the lack of suitable carrier. Here we hypothesis that Insoluble Bone Gelatin (ISBG) may be a good carrier for OP-1 in the induction of bone formation during spinal fusion. The aim of this study is to examine the efficacy of osteoconductive carrier, ISBG, for OP-1 in rabbit lumbar inter-transverse process fusion model.

Adult New Zealand White rabbits (n=32) underwent bilateral lumbar intertransverse process fusion at L5-L6. The animals were divided into four groups based on the materials implanted:

Autograft group,

Spinal fusion masses were evaluated by manual palpation, biomechanical testing, radiographic examination, micro-CT Scanning, and histological analysis six weeks after surgery.

ISBG+OP-1 group demonstrated significantly higher fusion rates (7/7) than autograft (3/7), ISBG (2/8), and OP-1 groups (2/7) (P< 0.05) based on manual palpation. In biomechanical testing, given the same moment, the fusion masses of ISBG+OP-1 group had less range of motions than those of other groups (P< 0.05) in main direction motion. Radiographic examination and micro-CT demonstrated that continuous trabecular pattern within intertransverse process area in ISBG+OP-1 group than other groups, and radiographic scores and bone volume base on micro-CT were also higher than other groups. Mature new bone formation was observed covering the surface of transverse processes in all four groups in histological findings. Continuous trabeculae connected two transverse processes and endochondral bone formation was observed attached the surface of ISBG in ISBG+OP-1 group. However, in other three groups, obvious gaps were noted in fusion masses and fibrous tissue was filled in these gaps.

In conclusion, OP-1 carried by ISBG results in more effective spinal fusion in posterolateral lumbar transverse fusion in rabbit model than autograft, ISBG or OP-1 alone.

Introduction and Aims: Treatment of rotator cuff tendon tear presents a significant therapeutic challenge to surgeons. Porcine small intestinal submucosa (SIS) is a biomaterial approved by TGA and FDA for the repair of rotator cuff tendon tear. The aims of this study are to evaluate the safety and efficacy of SIS.

Method: SIS purchased from DePuy Johnson & Johnson was examined by histology and PCR technique. The material was also implanted into mice and rabbits for the evaluation of biological reaction and inflammatory response. Porcine immunoreceptor DAP12 gene was used to examine if the material contained porcine DNA.

Results: Fresh SIS membrane before implantation contains multiple layers of spindle-shaped cells mixed with a small population of round-shaped cells. Chloro-acetate esterase staining showed that the round-shaped cells are positive, indicating that they are mast cells. The tissue architecture of SIS mimics to tendon structure as evidenced by H& E staining. To further confirm if cells present in SIS material were porcine origin, nested PCR for the amplification of DAP12 gene was used. The result demonstrated that SIS membrane contain porcine DNA materials.

Conclusion: SIS contains porcine cells and nuclei acid, which contradicts with current views that SIS is a cell-free biomaterial. Although no foreign body reaction of SIS was observed, SIS implant may cause chronic inflammation. Further studies should be conducted to confirm the clinical efficacy of SIS implant.

Introduction and Aims: Surgical correction of pelvic obliquity is an important component of spinal instrumentation for neuromuscular scoliosis, though instrumentation to the pelvis has high reported complication rates. This study evaluates the results of pelvic fixation during surgical correction of neuromuscular scoliosis in a consecutive series of 62 children and adolescents.

Method: A retrospective chart and radiographic review of 62 consecutive patients treated with spinal fusions to the pelvis as treatment for neuromuscular scoliosis was performed. Follow-up ranged from two to seven years. Diagnoses included cerebral palsy (36 patients), muscular dystrophy (16 patients), myelomeningocele (three patients), spinal muscular atrophy (three patients) and other disorders (four patients). Mean age at surgery was 13.5 years. Pelvic fixation techniques used included Luque-Galveston or iliosacral screw fixation. Correction of deformity in each patient was assessed with Cobb angle measurements of scoliosis, thoracic kyphosis, and lumbar lordosis. Pelvic obliquity and coronal decompensation was also assessed.

Results: The Luque-Galveston spinal instrumentation technique was used in 54 patients and iliosacral screw fixation was used in eight patients. Seventeen patients had an additional anterior release and fusion without instrumentation. The mean Cobb angle measured 73 degrees pre-operatively and 31 degrees (mean correction 59%) post-operatively. The mean Cobb angle on latest follow-up was 33 degrees (loss of correction 12%). Thoracic kyphosis remained essentially unchanged, as did lumbar lordosis (56 pre-op and 61 on follow-up). Pelvic obliquity corrected from a mean of 16 degrees pre-operatively to eight degrees on most recent follow-up. Mean pre-operative coronal decompensation measured 135mm, and follow-up decompensation measured 46mm. Eleven patients with Galveston fixation exhibited the ‘windshield-wiper’ sign, with a radiolucency of 2mm or more, though most were asymptomatic. Wound infection was observed in 6% (3/54) of the patients who underwent Galveston instrumentation and 50% (4/8) who had iliosacral screws. In patients treated with Galveston fixation, three had symptomatic prominant hardware and one had hardware breakage for an overall mechanical failure rate of 7% (4/54). In contrast, two patients with iliosacral screws had construct breakage and pseudoarthrosis for a mechanical failure rate of 25% (2/8), though the numbers in the iliosacral screw group are small.

Conclusions: In this series, Galveston pelvic fixation during spinal instrumentation treatment of neuromuscular scoliosis was associated with satisfactory results and with less complications than generally reported in the literature. This technique is recommended as the preferred method for pelvic fixation in severe neuromuscular scoliosis associated with pelvic obliquity.

Introduction and Aims: Large or recurrent rotator cuff tendon tears are difficult to treat effectively. Collagen bio-scaffolds have become available to reinforce a tendon repair or as an interpositional graft. This study compares the suitability of two collagen bio-scaffolds for autologous tenocyte implantation, and assesses the in vivo rotator cuff healing response with these grafts in a rabbit model.

Method: Tenocytes were isolated from rabbit tendon, cultured and seeded onto the Restore patch (DePuy), or the Matricel (Verigen) collagen membrane. Serial scanning electron microscopy examined tenocyte integration with the bio-scaffold, and extra-cellular matrix synthesis over time. A rotator cuff tendon defect was created in 50 rabbits and repaired by either: a) direct suture to tuberosity; b) Matricel interposition graft; c) Matricel interposition with autologous tenocytes; d) Restore patch interposition graft; e) Restore patch interposition with autologous tenocytes. Gross and histological evaluation were performed at four weeks and eight weeks post-surgery.

Results: Scanning electron microscopy of the Matricel membrane showed a rough surface characterised by a loose arrangement of collagen fibres capable of cell adhesion. SEM at one, three and five days after cell seeding, showed progressive integration of tenocytes into the three-dimensional membrane structure with extra-cellular matrix neosynthesis in the spaces between the native collagen fibres. SEM of the Restore patch showed a relatively smooth surface of highly compacted collagen fibres. Serial SEM after cell seeding showed relatively less tenocyte integration onto the membrane surface though tenocyte replication and matrix neo-synthesis was observed. All 50 rabbits regained normal gait at two weeks post-surgery. At sacrifice, no tendon ruptures had occurred at either time point in any of the five groups. At four weeks, the Matricel and Restore bio-scaffold membranes were partially absorbed, and a florid lymphocytic inflammatory response was evident surrounding the remaining membrane. By eight weeks, graft tissue had been resorbed further, the inflammatory response had decreased, and the regenerating tendon showed progressive remodelling. Autologous tenocyte implantation on both membranes improved the reparative tendon histological grade at eight weeks compared to membranes without cell implantation, and was equivalent to the direct repair group.

Conclusion: Autologous tenocytes can be implanted onto both Matricel and Restore collagen bio-scaffolds. Though both Xeno grafts induce an anti-inflammatory response in vivo, membrane resorption subsequently occurs. The healing response of large rotator cuff defects treated with interpositional collagen grafts is improved with autologous tenocyte implantation in a rabbit model.

Introduction Rotator cuff degeneration is considered to be a major factor in the pathogenesis of rotator cuff tendon tear. Degenerative weakening of the rotator cuff can result in irreversible complete cuff-tear arthropathy syndrome. Recently a porcine small intestinal submucosa (SIS) has been approved by TGA as biological implant for the repair of rotator cuff tendon tear. The aims of this study are to evaluate the safety and efficacy of SIS.

Methods A commercial brand of SIS was examined by histology and PCR technique. The material was implanted into mice and rabbits for the evaluation of biological reaction and inflammatory response. Next, we have used SIS to replace the rotator cuff tendon in rabbit (N=10) and compared to control (N=10). Histological examination was conducted at four and eight weeks after implantation. To further confirm if cells present in SIS material were of porcine origin, nested PCR for the amplification of DAP12 gene was used.

Results Fresh SIS membrane before implantation contain multiple layers of spindle-shaped cells mixed with a small population of round-shaped cells. Chloroacetate esterase staining showed that the round-shaped cells are positive, indicating that they are mast cells. The tissue architecture of SIS mimics tendon structure as evidenced by H & E staining. The SIS membrane contained porcine DNA materials. Subcutaneous implant of SIS in mice (by six) for up to seven days showed no obvious inflammatory response or foreign body reaction. The result demonstrated that SIS has remained in the region and mixed with regenerative fibrous tissue after eight weeks. In some cases there was a massive recruitment of lymphocytes along the surface of membrane. However, no foreign body reactive giant cells were observed.

Conclusions The result of this study indicated that SIS contains porcine cells and nucleic acid, which contradicts current views that SIS is a cell free biomaterial. Although no foreign body reaction of SIS was observed, SIS implant may cause chronic inflammation. Further studies should be conducted to confirm the clinical efficacy of SIS implant for rotator cuff tendon tear.