Lack of a central role for osteoprogenitor cells from the femoral canal in heterotopic ossification of the hip: an experimental study in a rat model.

We have developed an animal model to examine the formation of heterotopic ossification using standardised muscular damage and implantation of a beta-tricalcium phosphate block into a hip capsulotomy wound in Wistar rats. The aim was to investigate how cells originating from drilled femoral canals and damaged muscles influence the formation of heterotopic bone. The femoral canal was either drilled or left untouched and a tricalcium phosphate block, immersed either in saline or a rhBMP-2 solution, was implanted. These implants were removed at three and 21 days after the operation and examined histologically, histomorphometrically and immunohistochemically. Bone formation was seen in all implants in rhBMP-2-immersed, whereas in those immersed in saline the process was minimal, irrespective of drilling of the femoral canals. Bone mineralisation was somewhat greater in the absence of drilling with a mean mineralised volume to mean total volume of 18.2% (sd 4.5) versus 12.7% (sd 2.9, p < 0.019), respectively. Our findings suggest that osteoinductive signalling is an early event in the formation of ectopic bone. If applicable to man the results indicate that careful tissue handling is more important than the prevention of the dissemination of bone cells in order to avoid heterotopic ossification.

Rod-through-plate fixation of canine diaphyseal fractures.

UNLABELLED: Efficacy of the rod-through-plate fixation for fracture repair was evaluated in six clinical cases of canine long bone fractures. This fixation incorporates principles of intramedullary and extramedullary osteosynthesis for transverse and short oblique fractures of long tubular bones. The plate-through-rod device is comprised of one pair of curved rods, a connecting plate and two bone screws. The connecting plate has both a hole and a channel on each end. Curved rods have a long curved part and a straight part with a hole in it for screw fixation. All components are made up of medical stainless steel. Clinical and radiographical examinations were performed from week seven to18 months after the operation. Functional abnormalities were not observed at this period in five patients and all fractures were healed. In one patient screw stripping in the proximal fragment of the femur was detected radiologically and minimal implant dislocation was noted at seven weeks after the initial repair. The rod-through-plate fixation method gives strong fixation of bone fragments with minimal traumatization of soft tissue during the operation. The design of the rod-through-plate is intended to reduce pressure of the plate on the cortex in the area of the fracture, whereas the dynamic fixation provided by the intramedullary rods may allow micromotion, thus stimulating callus formation and avoiding implant-induced osteoporosis. CLINICAL RELEVANCE: The rod-through-plate fixator has a simple construction and its use expands the treatment possibilities for diaphyseal fractures of long bones.

Bone formation zones in heterotopic ossifications: histologic findings and increased expression of bone morphogenetic protein 2 and transforming growth factors beta2 and beta3.

Heterotopic ossifications (HOs) formed after total endoprosthetic replacement of the hip joint were collected during revision surgery (n = 7). Tissues collected during regular hip arthroplasty (n = 12) were used as reference. Histomorphometric analysis was performed for assessment of bone formation activity in HOs and reference bone. HOs were dissected with histological guidance into three zones: formed bone, zone of active bone formation, and zone with fibrous connective and fibrocartilagineous tissue. Relative expression of the mRNA for bone morphogenetic protein 2 (BMP-2), transforming growth factor beta2 (TGF-beta2), and TGF-beta3 was determined by reverse-transcription polymerase chain reaction relative to beta-actin. Expression of all three growth factors was higher than in orthotopic bone. Similarly, the osteoid surface density was increased in HOs. The levels of all growth factors were higher in the zone of active bone formation or remodeling than in the zone of formed bone. In matured HOs, the osteoid surface density as well as mRNA levels were lower, although still significantly raised, indicating that bone formation slows down after 2 years. Immunohistochemical analysis demonstrated the presence of TGF-beta1, TGF-beta2, TGF-beta3, and BMP-2 proteins in the zone of bone formation. We conclude that bone formation after heterotopic bone induction is initially intense, slows down within 2 years, and thereupon continues as active remodeling mainly on the border of HO. Our data indicate that BMP-2, TGF-beta2, and TGF-beta3 are involved in bone formation in HO.

Inter-observer reliability in the assessment of heterotopic ossification: proposal of a combined classification.

We applied four published classifications for assessment of heterotopic ossification after total hip arthroplasty (Arcq, Brooker, DeLee and Della Valle [1, 2, 5, 6]. The average incidence of heterotopic ossification varied from 19.8% to 27.7%. The inter-observer reliability of the various classifications was determined by Cohen's Kappa statistic. Kappa values ranged from 0.897 for Arcq's to 0.814 for Brooker's classification. In order to increase the reliability and consistency, we propose a new classification system combining Brooker's and Della Valle's classifications. This new classification preserves the high reliability of Della Valle's system and is comparable to previous publications since it includes Brooker's criteria.

The anterior glenohumeral joint capsule: macroscopic and MRI anatomy of the fasciculus obliquus or so-called ligamentum glenohumerale spirale.

The purpose of this study was to demonstrate the macroscopic and MRI anatomy of the fasciculus obliquus, otherwise known as the ligamentum glenohumerale spirale or spiral GHL of the anterior shoulder joint capsule. Conventional and MR arthrography (1.5-T device Somatom Symphony, Siemens with shoulder coil) images in standard planes were compared with gross anatomic dissection findings in six fresh shoulder specimens from three cadavers. The MR imaging protocol included T1, PD and DESS 3D WI sequences. The macroscopically recognisable band-the spiral GHL-was identified by anatomic dissection and MRI in all the specimens. It was best visualised by MR arthrography on axial and oblique sagittal planes (T1; PD WI) and appeared as a low signal intensity stripe within the superficial layer of the anterior joint capsule. The absence of the variable middle glenohumeral ligament did not influence the anatomic properties and the MR imaging of the spiral GHL. Diagnostic visualisation of the normal anatomic structures is a prerequisite to distinguish between normal and pathologic conditions. Anatomy of the spiral GHL can be used by radiologists for more detailed interpretation of the anterior shoulder joint capsule ligaments on MR images.

Treatment of children with Osteogenesis imperfecta in Estonia.

AIM: To analyse the changes in fracture rate, bone density and histology in children with Osteogenesis imperfecta receiving treatment with alendronate (oral bisphosphonate) and calcitriol. METHODS: Children treated at Tartu University Hospital from 1995 to 2001 were examined for Osteogenesis imperfecta. Radiographs and bone density measurements were obtained for all patients at the beginning of the study. Four patients also had bone biopsies prior to and one year after beginning treatment. The children were then given alendronate in weight-dependent dosages and also calcitriol. The number of fractures during the treatment period was recorded and follow-up bone density measurements were made. RESULTS: Fifteen patients were treated during the 6-y period; mean follow-up approximately 3 y. It was found that the number of bone fractures had decreased significantly (p < 0.0001). Bone density improved in all 15 patients. Histologic studies revealed an increased number of osteoblasts and thickness of bone trabeculae as well as a more regular bone lamellar structure at the time of the second operation. CONCLUSION: The complex treatment of Osteogenesis imperfecta should include alendronate and calcitriol to decrease fractures and improve bone mineral density.

Heterotopic ossification after total hip arthroplasty.

We studied 178 patients undergoing total hip arthroplasty (66 men and 112 women) retrospectively, with regard to the incidence and severity of heterotopic ossification and the significance of postoperative prophylaxis with non-steroid anti-inflammatory drugs. The overall incidence of heterotopic ossification was 32% 1 year after surgery. The factors increasing the incidence were male gender, previous arthroplasty of the contralateral hip joint, previous surgery on the hip, absence of preoperative treatment with non-steroidal anti-inflammatory drugs and an operating time of more than 100 min. The incidence of heterotopic ossification was lower in the patients of O blood group.

Bone healing models in rat tibia after different injuries.

AIMS: Gradual elaboration of an adequate and efficient multistage method for experimental remodelling of specific wound healing process--bone repair. Comparison of clinical characteristics with the results of microanatomy, histology, electronmicroscopy and computer morphometry. MATERIAL AND METHODS: An investigation of posttraumatic bone repair after internal fracture, excision and cortical perforation was carried out on 142 young adult male Wistar rats. The repair was studied in normal and affected animals (exercises, immobilization, isolation of periost) at 1-42 days after operation. RESULTS: The posttraumatic bone callus development and the related soft tissue repair, likewise the continuous remodelling, is an ordinary process of osteohisto- and organogenese. In trained rats the blood supply and bone formation is increased, whereas in immobilized animals it is inhibited and destroyed (osteoporose, pseudoarthrosis). After the injury some characteristics of bone repair histogenese will be became evident (after the perforation the primary endosteal and secondary periosteal ossification, inhibition of endosteal bone repair after the isolation of periost etc.). CONCLUSION: The posttraumatic bone healing, like embryohistogenese, has similar repair stages in all models of the experiments as well as similar tissue and cell responses (callus formation, its replacement, bone remodelling, etc.). However, the repair process in general (order of chondrous and/or bone callus stages, etc.) is variable and dependent on the mode and degree of injury. The use of bone cortex perforation in wound healing study is more recommendable as compared to internal fracture and excision (possibility of in situ study the periost and callus tissue compartments in bone repair machinery separately).

40 years of tissue banking in Estonia.

A survey is given of the development of tissue banking in Estonia during 40 years, in which we address methods of tissue preservation, application of preserved skeletal tissues in orthopaedics as well as issues of clinical and experimental research in this area. Preparation and use of demineralized and morselized bone allografts has been significant during the last ten years. Progress of endoprosthetic joint surgery has essentially increased the need for bone transplantation in orthopaedics.

Orthopedic surgery in Estonia.

We did a survey on the development of orthopedic surgery in Estonia, especially during the past 10 years, including education, hospital-based orthopedic surgery and orthopedic research. The main types of orthopedic operations were analyzed, on the basis of data from the Estonian Social Ministry, Bureau of Medical Statistics and several departments of orthopedic. On the average, 11,831 orthopedic operations were performed yearly during the years 1996-1998 in hospital departments.

Posttraumatic limb shortening: treatment with the Ilizarov distraction device.

BACKGROUND AND AIMS: Limb length inequality is not only a cosmetic problem, it is also a functional concern. The aim of the study was to analyse the cases of limb lengthening after their posttraumatic shortening. The study design is descriptive and comparative. MATERIAL AND METHODS: During the years 1979-1994 14 patients between 4-18 years of age were treated. Limb shortening was the result of premature closure of physeal plate and severe traumas with large bone defects. Ilizarov external devices for limb lengthening were used. The lengthening index was counted. The patients were divided into four groups: minor lengthening, bone transport, femoral lengthening, lengthening with using bone allografting. RESULTS: In group I the lengthening index was 29.9 days per centimetre (d/cm), in group II 21.7 d/cm, in group III 33.5 d/cm, in group IV 20.5 d/cm. The complication rate was 28%: 14% "minor" and 14% "major"-stiffness, wound necrosis. None of them affected the final result. In almost all cases the lengthening index was below 30 d/cm. CONCLUSIONS: The result of limb lengthening is not predictable in every separate case. Multiple lengthening may act on bone regeneration capacity.

Impaction bone-grafting increases the holding power of cancellous screws in the femoral head. A pull-out study in human cadaver hips.

We studied the effect of impaction of fresh cancellous bone or demineralized bone matrix (DBM) around cancellous screws in 25 cadaver femoral heads. The bone mineral content (BMC) of femoral heads was measured to determine if greater relative increase in holding power will be achieved by impaction-grafting, as the BMC of the specimen decreases. A 60% (p < 0.001) relative increase in the pull-out force was achieved by impaction-grafting with DBM, compared to non-grafted controls. The augmenting effect of fresh cancellous bone graft and DBM did not differ significantly. The relative improvement in holding power was not inversely correlated to femoral head BMC, but was inversely related to the pull-out resistance of non-grafted control screws. These findings suggest that impaction-grafting provides significantly better hold of cancellous screws in femoral heads.

The incidence of osteoporotic fractures at the University Hospital of Tartu, Estonia.

The incidence of typical osteoporotic bone fractures in 1351 women of various age groups was investigated, using the records of the traumatologic service and the census data. The fracture rates of different localization according to patients age were analyzed. The life style of the patients, previous diseases, used drugs etc. were clarified by questionnaire. The results of study indicated that the risk of falling may be related to menopausal status, self-reported arthritis and use of corticosteroids and diuretics. The most effective preventive measures of osteoporosis are discussed.

The effect of lengthening of the femur on the extensors of the knee. An electromyographic study.

Surface electromyography of the quadriceps femoris muscle was performed in seven patients in order to determine the effect of extensive lengthening of the femur on the muscles that extend the knee. Electromyograms were made during sustained (thirty-second) isometric extension of the knee, at an angle of flexion of the knee of 30 degrees, while a load equal to 15 per cent of body weight was applied to the leg just proximal to the ankle. The average circumference of the thigh was smaller, the motor-unit recruitment of the muscles was slower, and the fatigability was greater on the involved side compared with the uninvolved side. The vastus medialis exhibited greater fatigability and slower motor-unit recruitment than the rectus femoris or the vastus lateralis. The atrophy index of the involved muscles correlated well with the muscle fatigability, the preoperative limb-length discrepancy, the percentage of lengthening, and the motor-unit recruitment. Analysis also revealed a correlation between muscle fatigability and the percentage of lengthening of the bone and between muscle fatigability and the preoperative limb-length discrepancy. The percentage of lengthening correlated with the extent of motor-unit recruitment. The results of this study suggest that the amount of damage to neuromuscular tissue varies according to the extent of the lengthening of the femur. Of all of the knee extensors, the vastus medialis was affected the most.