Electron Microscopy and Synchrotron analysis of Heterotopic Ossification (HO) from blast-related amputees' has shown that HO is bone with a disorganised structure and altered remodelling. This research performs mechanical testing of HO to understand its biomechanical properties in an attempt to create an accurate model to predict its morphological appearance. The hypothesis of this work is that HO is mechanically mediated in its formation.

Synchrotron mechanical analysis of HO samples was performed to measure Young's modulus, ultimate strength and density distribution. A novel algorithm based on Wolf's law was implemented in a Finite Element (FE) analysis model of HO to take into account the differing mechanical and biological properties measured and the presence of HO outside the skeletal system.

An HO modeling factor, which considers boundary conditions, and regulates recruitment of the soft tissue into bone formation, results in a re-creatable formation of HO within the soft tissues, comparable to the appearance of HO seen in military amputees. The results and model demonstrates that certain types of HO are under the control of endogenous and exogenous mechanical stimulus. HO can thus be mechanically exploited in the casualty management and rehabilitation process to achieve better clinical outcomes.

Objectives

The most prevalent disorders of the shoulder are related to the muscles of rotator cuff. In order to develop a mechanical method for the evaluation of the rotator cuff muscles, we created a database of isometric force generation by the rotator cuff muscles in normal adult population. We hypothesised the existence of variations according to age, gender and dominancy of limb.

Objectives

The need for bone tissue supplementation exists in a wide range of clinical conditions involving surgical reconstruction in limbs, the spine and skull. The bone supplementation materials currently used include autografts, allografts and inorganic matrix components; but these pose potentially serious side-effects. In particular the availability of the autografts is usually limited and their harvesting causes surgical morbidity. Therefore for the purpose of supplementation of autologous bone graft, we have developed a method for autologous extracorporeal bone generation.

Introduction: The mitochondrial Translocator Protein 18 kDa (TSPO, previously named as the peripheral benzodiazepine receptor - PBR) is involved in cellular respiration, steroidogenesis and apoptosis. In our recent study we reported on the role of the synthetic pharmacological ligands to the TSPO in enhancing human osteoblast catabolism. There is also a previous evidence of the existence of an endogenous ligands to the TSPO, but their role in the human osteoblast physiology hasn’t been verified yet. Porphyrine IX has been found having affinity to the TSPO. Therefore we hypothesize that human osteoblast metabolism might be mediated by the porphyrine IX and the mode of its action is similar the synthetic ligand to the TSPO.

Methods: Cell cycle of the cultured human derived osteoblast- like cells, following exposure to Porphyrine IX, endogenous ligand to TSPO, and N,N-di-n-hexyl 2-(4- fluorophenyl)indole-3-acetamide (FGIN-1–27), synthetic ligand to the TSPO, was determined by flow cytometry (FACS). These ligands’ affect on cell number, metabolic activity, i.e. cellular fluorodeoxyglucose ([¹⁸F]-FDG) incorporation and alkaline phosphatase activity, and cell death rate, i.e. LDH activity in the culture media, were assayed. The semi-quantitative response of TSPO to exposure to these ligands was estimated by Western blotting. Six samples of cultured cells for each condition were used. The t test was implemented for the statistical analyses. P values below.05 considered as statistically significant

Results: Cell count significantly decreased following exposure to FGIN-1–27 or porphyrine IX. Cellular [¹⁸F]-FDG incorporation and alkaline phosphatase activity were suppressed by both ligands. Cell cycle analysis showed a significant decrease in the fraction of cells in the G1 and G2/M phases when exposed to each ligand with a higher proportion of necrotic and apoptotic cells.

Western blotting showed a decrease in TSPO abundance following treatment by both ligands. LDH activity in culture media significantly increased following exposure to FGIN-1–27 or porphyrine IX.

Discussion: We show that FGIN-1–27 and porphyrine IX have a similar cell death inducing affect on human osteoblast-like cell in vitro. This affect is parallel to the inhibition of the cellular metabolism. Since both ligands similarly reduce the availability of TSPO we postulate that their mode of action is similar by affecting this mitochondrial structure with sub sequential induction of cell death, i.e. apoptosis and necrosis. Therefore we suggest that human osteoblast metabolism and cell cycle are mediated through TSPO and that porphyrine IX might be an active endogenous ligand to the TSPO having a regulatory affect on the human bone cell cycle.

Introduction: The diagnosis of cuff tendon pathology is usually based on physical examination, which has a limited predictive value. The ultimate cost effective diagnostic tool for this purpose should combine the simplicity and low cost of the physical examination with precision of the imaging scans. Since the pathological process involving the rotator cuff structures is usually intrinsic to the muscle and tendon tissue, one of its main expressions, apart of pain, will be weakness of the muscle involved. Measurements of muscle strength may potentially provide a valuable diagnostic tool for evaluation of integrity of a specific muscle or a group of muscles. The purpose of the study is to evaluate the normal patterns of the isometric strength curves of the rotator cuff muscles.

Methods: Isometric time-force distribution for suspraspinatus, infraspionatus and subscapularis muscles in 400 healthy volunteers was measured, i.e.. 50 healthy individuals of both sexes for every decade of age from twenty to sixty years of age were evaluated. Specially designed dynamometer with measurement rate of 5 Hz was used. The measurements were done in a standard body-arm positions in order to eliminate the influence of the synergistic contribution of other muscles. The force- time curves were presented as moment of force values normalized to the lean body mass of the examinees. The characteristics curves of the study groups were compared by non parametric statistical analysis, since not normal distribution of values was found.

Results: Isometric strength of each of the rotator cuff muscles was higher in dominant limbs, higher in men in every age group and gradually rises from second to fifth decade of life in both sexes. The significant drop in muscle force was evident only in the sixth decade of life in both sexes. The force-time curves were characteristic and different in the different studied groups.

Discussion: A data base of normal isometric strength values of rotator cuff muscles in healthy adult population was established. This provides an effective comparative tool for the further evaluation of force-time curves in patients with rotator cuff pathology. The unpredictable evidence of significant rise of rotator cuff muscles’ strength with increasing age challenges the present concepts of the understanding of rotator cuff degeneration pathophysiology and its treatment. The decrease in rotator cuff isometric strength in the sixth decade of life is consistent with the higher incidence of non symptomatic rotator cuff intrinsic pathology at this age

Introduction Efficient control of osteoblast metabolism is crucial for the development of methods for enhancement of bone fracture repair and in the treatment of osteoporosis. If extracellular matrix elaboration by osteoblast could be controlled on the cellular level, new theurapeutical means might be developed. The current methods for osteoblast metabolic manipulation include mechanical, electromagnetic, hormonal and biochemical, i.e. growth factors and cytokines, means. All this methods have different degrees of therapeutic success. Finding of additional pathways of metabolic stimulation of osteoblast will provide an important insight for the understanding of human bone mass maintenance. The recent report of the existence of peripheral ben-zodiazepine receptor(PBR) in mammalian fibroblast arises the possibility of the existence of an unknown cellular pathway for mesenchymal cells metabolic regulation through this receptor. The PBR is a part of the mitochondrial permeability transition complex with important role in cell proliferation, differentiation, steroidogenesis, immunity and apoptosis, i.e. this complex is involved in most of the cellular metabolic activities. The PBR was identified in various organs, especially with enhanced steroidogenetic activity, but never has been investigated in bone. Therefore PBR’s identification in the human osteoblast may reveal a new cellular pathway of its metabolism.

Methods Cultures of confluent layers of osteoblast-like cells originated from human cancellous bone from distal femur. The samples were taken during osteoarthritic knee replacements. Chips of cancellous bone, 2 – 3 grams in total, were incubated in DMEM with heat-inactivated fetal calf serum (10%), 20mM HEPES buffer, 2mM L-glutamine, 100 μ M ascorbate-2-phosphate, 10nM dexam-etasone, 50 U ml-ml penicillin, 150μml-ml streptomicin at 37°C in humidified atmospheric environment of 95% air with 5% CO₂ ( v:v ) for 30 days. Human osteoblast-like cells grew out from the chips as adherent to the plastic culture plates until confluency. The human bone cell cultures obtained by this method have been shown previously to express osteoblast-like characteristics.

The PBR in the homogenized osteblast-like cells was identified by using its selective ligand PK11195. The affinity and density of the PBR was estimated by the scatchard analysis.

Results We found that binding of the ligand [³H]PK11195 to the human osteoblast PBR is saturable with a single population of binding sites (r=0.92 – 0.95). The equilibrium dissociation constant (K_d) equaled 9.15-9.34 nM and density of receptors (B_max) was 7,672–7,691 fmol/mg protein.

Discussion The PBR receptor was identified in the human osteoblast with affinity to the PK11195 in the same magnitude as previously found in other tissues. The density of the PBR in the osteoblast appeared higher comparing to uterus, kidney, brain and placenta from different mammalian origin. PBR’s density in osteoblast is comparable only to the adrenal tissue, that is known to have its highest values. PBR density in the human osteoblast is also higher than in the rat’s skeletal fibroblast, and although this may suggest a higher differrention of the osteoblast, the interspecies comparison might be misleading. These data suggest that the human osteoblast is one of the important sites rich with PBR. The exact role of the PBR in the human osteoblast metabolism is not known yet and will be further investigated.

Introduction: This study investigates the survival (and radiological loosening) rates of prostheses following uncemented Total Shoulder Arthroplasties (TSAs) focusing on the glenoid baseplate fixation.

Methods: ALL uncemented TSAs inserted in one shoulder unit from 1989 to 2001 were entered onto a database prospectively and the patients monitored to death or failure of the implant, resulting in revision surgery. Over 80% of the surviving implants were monitored on sequential radiographs and the radiological loosening rate was observed. 273 TSAs have been monitored – 193 with a porous coated glenoid baseplate and 80 with a hydroxyapatite coating on top of the porous coating.

Results: The Survival rates (%) of the non-HA coated baseplates at 1 to 12 years using the Life Table Method were:− 97, 93, 89, 83, 83, 81, 79, 79, 77, 75, 75 & 75% respectively. The Survival rates for the HA coated glenoid base-plates at 1 to 4 years were 100, 97, 93, & 93% respectively. Failures were predominantly due to mechanical loosening and glenoid disassembly with only 3 cases of infection documented. Thus by 4 years there was a statistically significant improvement in survival of the glenoids. Survival rates were further reduced when radiological loosening was taken into account. The earlier series was analysed to assess the survival of prostheses inserted for RA and OA. The survival rates at 5 and 10 years were 78% & 70% for OA and 96% and 88% for RA.

Discussion & Conclusions: This Life Table analysis confirms the early benefit from the use of hydroxy-apatite coating of the glenoid implant of a TSA. Further improvements, particularly in relation to reducing further the small risk of disassembly are underway.

Introduction: Inflammatory or degenerative processes of glenohumeral joint lead to pain and restriction of movements of the shoulder. As with the treatment of disabling arthritis in the other large joints, prosthetic replacement of the glenohumeral joint has gained in popularity because of its efficacy in relieving pain. Several designs for the total shoulder replacement (TSR) prostheses are currently used for the cemented and cementless implantation. The uncemented prostheses were developed in order to achieve a “biological” fixation of the implant to the adjacent bone. No survivorship data exists to compare these devices to the original TSR prostheses for cemented implantation, although this information is crucial for the decision making regarding their use. We present the long term survival rates of the Bio-Modular TSR prosthesis for uncemented implantation.

Methods:The Bio-Modular TSR prosthesis was implanted in 90 patients between 1989–1994 (15 men and 75 women, mean age 61 years, range 19–92 years). This prosthesis was the first to use an anatomical, offset humeral head, based on the study on the bony anatomy of the upper humerus. The mean follow-up period was 8.8 years. Survivorship analysis, according to the method described by Murray et al. and based on Rothman’s formula for the confidence limits determination, was used for the outcome evaluation of all the prostheses studied. The criterion for failure in this series was are-operation on the shoulder with a removal of part or all of the prosthesis.

Results: The ten-year cumulative survival rates of the Bio-Modular prosthesis was 71.7%.

The main cause for this low survivorship rate is the low survivorship of this prosthesis among patients with primary osteoarthritis, 61.4% ten years survivorship. Conversely among the patients with rheumatoid arthritis the ten years survivorship was considerably higher (86.9%). The main cause of failure of this prosthesis was related to the glenoid component and was either due to aseptic glenoid component loosening (in 54% of the failed cases) or a failure (uncoupling) of the polyethylene bearing liner in 17% of failed cases. Furthermore about 70% of the failed cases occurred during the first four postoperative years showing an overall four years cumulative survivorship rate of 80.9%.

Discussion: The survivorship data presented here indicate that the use of the Bio-Modular TSR prosthesis in patients with osteoarthritis produces less favorable results, comparing to the classical (Neer II) cemented designs. Therefore, the use of this prosthesis in patients with osteoarthritis should be reconsidered. But the higher survival of the prosthesis in the patients with rheumatoid arthritis suggests its safe use in the rheumatoid patients.

This study investigates the survival (with gross radiological loosening) rates of prostheses following uncemented Total Shoulder Arthroplasties (TSAs) focusing on the glenoid baseplate fixation.

All uncemented TSAs inserted in one shoulder unit from 1989 to 2001 were entered onto a database prospectively and the patients monitored to death or failure of the implant, resulting in revision surgery. Over 80% of the surviving implants were monitored on sequential radiographs and the radiological loosening rate was observed. 273 TSAs have been monitored – 193 with a porous coated glenoid baseplate and 80 with a hydroxyapatite coating on top of the porous coating.

The Survival rates (%) of the non-HA coated base-plates at 1 to 12 years using the Life Table Method were:- 97, 93, 89, 83, 83, 81, 79, 79, 77, 75, 75 & 75% respectively. The Survival rates for the HA coated glenoid baseplates at 1 to 4 years were 100, 97, 93, & 93% respectively. Failures were predominantly due to mechanical loosening and glenoid disassembly with only 3 cases of infection documented. Thus by 4 years there was a statistically significant improvement in survival of the glenoids. Survival rates were further reduced when radiological loosening was taken into account. The earlier series was analysed to assess the survival of prostheses inserted for RA and OA. The survival rates at 5 & 10 years were 78% & 70% for OA and 96% & 88% for RA.

This Life Table analysis confirms the early benefit from the use of hydroxyapatite coating of the glenoid implant of a TSA. Further improvements, particularly in relation to reducing further the small risk of disassembly are underway.

Topical treatment of infected wounds has a crucial role as an adjuvant to surgical debridement. Solutions currently used for local would treatment have either low antiseptic properties with low irritating effect, such as physiologically balanced solutions acting mostly by a mechanical irrigating effect, or antiseptic solutions which cause chemical irritation of the surrounding tissues. The use of topical substance with effective antiseptic properties, which is also not irritating to surrounding healthy tissues, should improve significantly the effectiveness of infected wound treatment.

Previous reports on the use of Hexamethylenebiguanide solution for local antiseptic treatment in infected wounds indicated on a good curative effect without any local or systemic side effects. Unfortunately none of these reports is based on well designed statistical data which is essential for the safe and skilled use of any pharmaceutical agent.

We present the results of controlled prospective double-blind study comparing the topical use of 0.1% Hexamethylenbiguanide solution with non lactated Ringer solution as agents for a topical treatment of infected wounds in extremities. The group of 104 patients with ischemic, combat, post surgical or due to open fracture wounds treated by either of these solutions following surgical debridement without additional systemic antibiotic use. According to the strict follow-up protocol, wounds’ healing was evaluated on a weekly basis. In the group of patients treated by the 0.1% Hexamethylenbiguanide solution, 75% rate of a complete wound healing was observed. In the control group the rate of healing was 52% [p=0.026, Chi square test, Figure 1]. These results indicate the high effectiveness of the Hexamethylenbiguanide as a topical agent for infected wound treatment.