Aims

The aim of this study was to analyze how proximal radial neck resorption (PRNR) starts and progresses radiologically in two types of press-fit radial head arthroplasties (RHAs), and to investigate its clinical relevance.

Aims

The aim of this study was to analyze the results of two radiocapitellar prostheses in a large case series followed prospectively, with medium-term follow-up.

Aims

The aim of the study was to analyze the results of primary tendon reinsertion in acute and chronic distal triceps tendon ruptures (DTTRs) in the general population.

Posterolateral spinal fusion (PSLSF) in rabbits is a challenging model for bone substitutes because the transverse processes are extremely thin and the space to be filled with bone is greater than critical and meiopragic in terms of vascularity.

Several investigators have shown beneficial effects of PRP in bone and soft-tissue healing processes. However, controversial results have been reported in clinical setting analysing the effectiveness of PRP. Aim of the present study was to test the effectiveness of PRP in experimental model of PLSF in rabbits.

Aims: Aims of this study was to perform a quantitatively evaluation of newly formed bone, vascular density (VD) and their correlation in animal model of posterolateral spinal fusion based on skeletal stem cells (SSCs) combined with a coral.

Methods: 15 rabbits received cell-material constructs, 15 rabbits were sham-operated (decortication of transverse apophyses), 15 rabbits received material alone. After 6 months the animals were sacrified. We performed a semi-quantitative and quantitative histologycal analysis of the fusion mass. To assess the VD, sections of the fusion mass were immunolabelled for alpha-smooth muscle actin as a vascular marker.

Results: No complete fusion was observed in all groups and no bone was formed in the interapophyseal region. Aboundant newly formed bone was observed in the peri-apophyseal regions in 60% of cases. The quantitative analysis showed a significantly higher amount of bone and VD in animals treated with cells and/or biomaterial alone compared to sham (p< 0.05). Periapophyseal VD and new bone formation was significantly higher compared to interapophyseal region in all groups (p< 0.05). Positive correlation exist between newly formed bone and vascolar density (p = 0,0009).

Conclusions: Interapophyseal region is scarcely vascolarized. The study shows a positive correlation between VD and osteogenesis. The inadequacy of staminal cells could be related with the poor survival after the implant. For the use of stam cells in the APL are necessary more studies in order to clarify the survival and in situ differentiation of the grafted cells in short and mid term.

Posterolateral spinal fusion is considered one of the most challenging condition for bone graft substitutes since using autogenous bone graft pseudarthrosis have been reported in 30% of cases.

MATERIALS AND METHODS.We develop a model of posterolateral spinal fusion in the rabbit based on skeletal stem cells (SSCs) loaded into a coral-hydroxyapatite material (Pro-Osteon 500RTM). 15 rabbits received cell-material constructs, 15 rabbits were sham-operated (decortication of transverse apophyses), 15 rabbits received material alone. The animals were housed for 6 months and radiographically monitored. At sacrifice, the explanted spine was analyzed by conventional and high resolution (Faxitron) radiography, and the outcome judged, blind of histology results, by two orthopedic surgeons.

RESULTS: radiographic evaluation showed a fusion rate rate of 90% in animals treated with cell constructs or biomaterial alone, and no fusion in the sham controls. Histology revealed abundant new bone formation directly on the scaffold in the cell construct and biomaterial alone groups, but no evidence of bone formation in the midregion of the interapophyseal space, where poorly vascular, dense fibrous tissue was observed.

CONCLUSIONS: The study shows that:

1) the cell-biomaterial constructs which per se were highly efficient in previous animal studies, used in different absolute quantities but identical ratios were not efficient in the direct preclinical model.

Since several spinal conditions are currently treated with spinal fusion, alternatives to autogenous bone graft in spinal surgery have been under study for many years. Results have shown that, compared to other non.-spinal conditions, such as filling bone cavities, spinal fusion, in particular posterolateral fusion, is much more challenging due to the reduced area of the graft bed. As a result, most of the bone substitutes are still under investigation and their effectiveness in the clinical setting has yet to be demonstrated.

In recent years the authors analysed several bone graft substitutes using an animal model which has been widely used in experimental spinal fusion. In particular, porous ceramics have been used alone or with osteoin-ductive material such as fresh bone marrow or cultured mesenchymal stem cells. The results of these studies have shown that with ceramic alone a percentage of solid fusion similar to that with autogenous bone graft cannot be achieved. However, compared to the latter, more favorable results have been obtained when ceramics are loaded with mesenchymal stem cells. The addition of fresh bone marrow to ceramics also increases the fusion rates; however, in this case new bone formation was mainly found in the peripheral portions of the graft and to a lesser extent than when cultured mesenchymal stem cells were used.

Aternatives to autogenous bone graft for spinal fusion have been investigated for many years. It has been shown that osteoconductive materials alone do not give a rate of fusion which is comparable to that of autogenous bone graft. We analysed the effectiveness of porous ceramic loaded with cultured mesenchymal stem cells as a new graft material for spinal fusion in an animal model.

Posterolateral fusion was carried out at the L4/L5 level in 40 White New Zealand rabbits using one of the following graft materials: porous ceramic granules plus cultured mesenchymal stem cells (group I); ceramic granules plus fresh autogenous bone marrow (group II); ceramic granules alone (group III); and autogenous bone graft (group IV). The animals were killed eight weeks after surgery and the spines were evaluated radiographically, by a manual palpation test and by histological analysis.

The rate of fusion was significantly higher in group I compared with group III and higher, but not significantly, in group I compared with groups II and IV. In group I histological analysis showed newly formed bone in contact with the implanted granules and highly cellular bone marrow between the newly formed trabecular bone. In group II, thin trabeculae of newly formed bone were present in the peripheral portion of the fusion mass. In group III, there was a reduced mount of newly formed bone and abundant fibrous tissue. In group IV, there were thin trabeculae of newly formed bone close to the decorticated transverse processes and dead trabecular bone in the central portion of the fusion mass.

In vitro cultured mesenchymal stem cells may be loaded into porous ceramic to make a graft material for spinal fusion which appears to be more effective than porous ceramic alone. Further studies are needed to investigate the medium- to long-term results of this procedure, its feasibility in the clinical setting and the most appropriate carrier for mesenchymal stem cells.

We have studied, prospectively, 116 patients with motor deficits associated with herniation of a lumbar disc who underwent microdiscectomy. They were studied during the first six months and at a mean of 6.4 years after surgery. Before operation, muscle weakness was mild (grade 4) in 67% of patients, severe (grade 3) in 21% and very severe (grade 2 or 1) in 12%. The muscle which most frequently had severe or very severe weakness was extensor hallucis longus, followed in order by triceps surae, extensor digitorum communis, tibialis anterior, and others.

At the latest follow-up examination, 76% of patients had complete recovery of strength. Persistent weakness was found in 16% of patients who had had a mild preoperative deficit and in 39% of those with severe or very severe weakness. Muscle strength was graded 4 in all patients with persistent weakness, except for four with a very severe preoperative deficit affecting the L5 or S1 nerve root. They showed no significant recovery. Excluding this last group, the degree of recovery of motor function was inversely related to the preoperative severity and duration of muscle weakness. The patients’ subjective functional capacity was not directly related to the degree of recovery except in those with persistent severe or very severe deficit.

We analysed prospectively 26 patients who had revision operations for ipsilateral recurrent radicular pain after a period of pain relief of more than six months following primary discectomy. They were assessed before the initial operation, between the two procedures and at a minimum of two years after reoperation. MRI was performed before primary discectomy and reoperation. Fifty consecutive patients who had a disc excision during the study period but did not have recurrent radicular pain, were analysed as a control group.

Of the study group 42% related the onset of recurrent radicular pain to an isolated injury or a precipitating event, but none of the control group did so (p < 0.001). T2-weighted MRI performed before primary discectomy showed that patients in the study group had significantly more severe disc degeneration compared with the control group (p = 0.02). Intraoperative findings revealed recurrent disc herniation in 24 patients and bulging of the disc in two, one of whom also had lateral stenosis. Epidural scarring was found to be abundant, intraoperatively and on MRI, in eight and in nine patients, respectively.

At the last follow-up, the clinical outcome was satisfactory in 85% of patients in the study group and in 88% of the control group (p > 0.05). Work or daily activities had been resumed at the same level as before the onset of symptoms by 81% of the patients in the study group and 84% of the control group. No correlation was found between the amount of epidural fibrosis, as seen intraoperatively and on MRI, and the result of surgery. The recurrence of radicular pain caused no significant changes in the psychological profile compared with the assessment before the primary discectomy.

We made a prospective study of 43 consecutive patients treated for intraforaminal (34) or extraforaminal (9) herniations of a lumbar disc by excision through an interlaminar approach, using an operating microscope. The intraforaminal herniations were contained or extruded in 52% and sequestrated in 47%; for extraforaminal herniation the proportions were 66% and 33%, respectively. There was additional posterolateral protrusion or spinal stenosis at the level of the lateral herniation in seven and four cases, respectively. The patients were reviewed at three months and two years after surgery. Radiographs showed three grades of facetectomy: grade I, removal of 50% or less, grade II, excision of 51% to 75%, and grade III, subtotal or total facetectomy.

For intraforaminal herniations the results were excellent or good in 88% of patients when reviewed at three months and in 91% at two years. For extraforaminal herniations, there was an excellent or good outcome in 89% of patients in the short term and in all in the long term. The facetectomy had been grade I in 14 and grade II in 25; it had been grade III in four, but only one had had total facetectomy. No patient had developed vertebral hypermobility as a result of the operation.

An intralaminar approach using an operating microscope can provide adequate access to a lateral protrusion. It has the advantage of allowing the treatment of posterolateral protrusion or posterior annular bulge and of spinal stenosis at the same level.

We reviewed 25 diabetic (mean age 68 years) and 25 non-diabetic patients (mean age 71 years) who had undergone decompression for lumbar spinal stenosis at a mean of 3.4 years after operation to determine whether diabetes affected the outcome of surgery. The preoperative symptoms were similar in the two groups except that an abrupt onset of symptoms, the presence of night pain and the absence of any posture-related pain relief were recorded only by diabetic patients. Nerve-conduction velocity was slowed in 80% of the diabetic and in 25% of the non-diabetic patients. Peripheral vascular deficiency was diagnosed in 20% of patients with diabetes and in 4% of non-diabetics. The outcome of surgery was similarly successful in the two groups. Mistaken preoperative diagnosis was the cause of failure in three diabetic patients, two with diabetic neuropathy and one with diabetic angiopathy.

We assigned 67 patients with central lumbar stenosis alternately to either multiple laminotomy or total laminectomy. The protocol, however, allowed multiple laminotomy to be changed to total laminectomy if it was thought that the former procedure might not give adequate neural decompression. There were therefore three treatment groups: group I consisting of 26 patients submitted to multiple laminotomy; group II, 9 patients scheduled for laminotomy but submitted to laminectomy; and group III, 32 patients scheduled for, and submitted to, laminectomy. The mean follow-up was 3.7 years. Bilateral laminotomy at two or three levels required a longer mean operating time than total laminectomy at an equal number of levels. The mean blood loss at surgery and the clinical results did not differ in the three groups. The mean subjective improvement score for low back pain was higher in group I but there was also a higher incidence of neural complications in this group. No patient in group I had postoperative vertebral instability, whereas this occurred in three patients in groups II and III, who had lumbar scoliosis or degenerative spondylolisthesis preoperatively. Multiple laminotomy is recommended for all patients with developmental stenosis and for those with mild to moderate degenerative stenosis or degenerative spondylolisthesis. Total laminectomy is to be preferred for patients with severe degenerative stenosis or marked degenerative spondylolisthesis.

We reviewed 40 patients treated surgically for lumbar stenosis at an average time of 8.6 years after operation. In 32, total laminectomy had been performed and in eight bilateral laminotomy, both at one or more levels. Of the 16 patients with degenerative spondylolisthesis, ten had had a concomitant spinal fusion. Patients were assigned to one of four groups according to the amount of bone regrowth: group 0 had no regrowth and groups I, II, and III, had mild, moderate or marked regrowth, respectively. Only 12% of the patients showed no bone regrowth; 48% were assigned to group I, 28% to group II and 12% to group III. Imaging studies showed varying degrees of recurrent stenosis in patients with moderate or marked bone regrowth. All patients with degenerative spondylolisthesis showed bone regrowth, which was more severe in those who had not had a fusion. The clinical results were satisfactory in most of the patients with mild or no bone regrowth and significantly less good in those with moderate or marked regrowth. In the group with degenerative spondylolisthesis, the proportion of satisfactory results was significantly higher in patients who had had spinal fusion. The long-term results of surgery for lumbar stenosis depend both upon the amount of bone regrowth and the degree of postoperative vertebral stability.