Purpose of the study: Percutaneous compressive plating (PCCP) enables minimally invasive surgery using closed focus technique. We report a prospective consecutive series of 67 fractures (December 2003 – February 2005) followed to bone healing.

Material and methods: Mean patient age was 83 years (range 37–95) with 83% females in a frail population (ASA 3, 4). Two-thirds of the patients had unstable fractures (AO classification) which were reduced on an orthopedic table under fluoroscope. Two minimal incisions were used to insert the material without opening the fracture and without postoperative drainage. Blood loss was noted. Verticalization and weight bearing were encouraged early depending on the patient’s status but were never limited for mechanical reasons. Patients were reviewed at 2, 4 and 6 months.

Results: Anatomic reduction was achieved in 84% of hips, with screw position considered excellent for 45, good for 14, and poor for 6. There were no intraoperative complications. The material was left in place. The hemoglobin level fell 2.2 g on average. Mean operative time was 35 minutes and the duration of radiation exposure 60 seconds. Mean hospital stay was 13 days. General complications were: urinary tract infections (n=10), phlebitis (n=2), talar sores (n=5). Gliding occurred in three cases (4%) with telescopic displacement measuring less than 10 mm in ten cases. There were two varus alignments with no functional impact. There were four deaths within the first three weeks. All fractures healed within three months.

Discussion and conclusion: PCCP has its drawbacks (mechanical, stabilization) as do all osteosynthesis methods used for trochanteric fractures. The technique is reliable and reproducible and is indicated for all trochanteric fractures excepting the subtrochanteric form. PCCP has the advantage of a closed procedure with a minimal incision and limited blood loss for a short operative time. An advantage for this population of elderly frail subjects (ASA 3, 4). PCCP enables immediate treatment with a low rate of material disassembly compared with other techniques.

We reviewed retrospectively 45 patients (46 procedures) with bladder exstrophy treated by bilateral oblique pelvic osteotomy in conjunction with genitourinary repair.

The operative technique and post-operative management with or without external fixation are described. A total of 21 patients attended a special follow-up clinic and 24 were interviewed by telephone. The mean follow-up time was 57 months (24 to 108).

Of the 45 patients, 42 reported no pain or functional disability, although six had a waddling gait and two had marked external rotation of the hip. Complications included three cases of infection and loosening of the external fixator requiring early removal with no deleterious effect. Mid-line closure failed in one neonate managed in plaster. This patient underwent a successful revision procedure several months later using repeat osteotomies and external fixation.

The percentage pubic approximation was measured on anteroposterior radiographs pre-operatively, post-operatively and at final follow-up. The mean approximation was 37% (12% to 76%). It varied markedly with age and was better when external fixation was used. The wide range reflects the inability of the anterior segment to develop naturally in spite of close approximation at operation.

We conclude that bilateral oblique pelvic osteotomy with or without external fixation is useful in the management of difficult primary closure in bladder exstrophy, failed primary closure and secondary reconstruction.

Background: Although either anterior or posterior corrective scoliosis surgery has been reported in Jehovah’s Witnesses, we did not find any reports of single stage combined anterior and posterior scoliosis surgery being done in these patients. We report our experience in one such case.

Methods: This is a case report of a 14 year old female Jehovah’s Witness who had cerebral palsy with total body involvement presented with right sided thoracolumbar scoliosis. She was wheel chair bound and was being treated in a spinal brace. She had a partially correctible thoracolumbar curve from T5 to L2 measuring 94°, which reduced to 74° in brace. Her parents were counselled regarding scoliosis surgery. They consented for the surgery and also signed a special consent form for Jehovah’s witnesses specifying that they would prefer their child not to have transfusion of blood or blood products under any circumstances. They were explained that in case of excessive bleeding, further surgery may need to be deferred.

Results: Although her pre-op Haemoglobin was 14.3 g/dl, she was given oral ferrous sulphate because of low serum ferritin level (34 mcg/L). After induction of anaesthesia, intra operative hemodilution was performed using 900 ml of crystalloid. During surgery aprotinin infusion was used with controlled hypotension and cell salvage. Anterior release was performed followed by posterior instrumentation. The operation lasted for 8 hours. Central venous pressure and arterial oxygen saturation remained stable throughout the operation. She recovered well following surgery, with post-operative haemoglobin of 9.8 g/dl and was discharged on the7th post-operative day. Oral iron supplementation has been continued after surgery.

Conclusion: Due to religious reasons, Jehovah’s Witnesses do not accept transfusion of blood and blood products, which makes major surgery like scoliosis correction difficult as it involves a significant amount of blood loss. Such patients benefit from pre-operative iron supplementation, pre-operative haemodilution, intraoperative hemodilution, cell salvage, use of Factor 7, aprotinin and erythropoietin. These modalities have made it possible to perform major operations like scoliosis surgery in this group of patients.

Purpose: Congenital proximal radioulnar synostosis is a rare anomaly of failure of segmentation of the radius and ulna resulting in a fixed rotational position of the forearm from neutral to maximum pronation. Several surgical options have been proposed for the treatment of this condition. We have treated six forearms in five children with pronation deformity using derotational osteotomies of the radius and ulna with postoperative wire stabilisation of the ulna. The surgical technique and results of treatment with this method are presented.

Methods: With this technique, osteotomies were performed at the midshaft of the ulna and the distal diaph-yseal-metaphyseal junction of the radius. The insertion of intramedullary Ilizarov wires facilitated manual derotation of the radius and ulna to a functional position of 100 supination of the forearm. Postoperatively, the forearm was immobilised in a cast for an average of 6.3 weeks and the wire was removed when there was evidence of union. 3 boys and 2 girls with a mean age of 4.9 years underwent surgery with this method and were followed-up for an average of 29 months (range 12 to 43 months).

Results: Forearm position improved from an average pronation deformity of 68.3 degrees to the pre-planned position of 100 degrees supination in all cases. Bone union was achieved in all six forearms by 6.3 weeks. At their most recent follow-up, there was no loss of correction evident in any of the patients. There was one complication, namely haematoma formation at the radial osteotomy site mimicking compartment syndrome and requiring exploration, although no soft tissue compromise was evident.

Conclusion: The principal advantages of this technique include the ease of the surgical approach for the distal radial osteotomy, the longterm maintenance of rotational correction and the need for single wire stabilisation of the ulna only, which in theory reduces the potential risk of implant-related complications. We conclude that this modified forearm derotational osteotomy with wire stabilisation of the ulna alone is a safe and effective method for treating pronation deformity in children with congenital proximal radioulnar synostosis, although vigilance for early soft tissue complications is necessary.

Normal acetabular development in developmental dysplasia of the hip (DDH) depends upon early and maintained congruent reduction. Computed tomography is an accepted method for evaluating this and attempts to quantify hip reduction, by various angular and linear measurements, have been reported.

The aim of this study was to assess initial CT scans, following open reduction in the older child with DDH, with comparison of outcome to evaluate prognostic value.

Method: Thirty consecutive patients underwent open reduction for DDH, with a mean age of 25.9 months at the time of operation. Acetabular morphology and the position of the femoral head were evaluated on the initial CT scan, taken on the first postoperative day, and AP pelvic radiograph taken at the latest follow-up.

Results: The acetabulae of the dislocated hips were found to be significantly more anteverted than the normal. The dislocated hips also had significantly increased lateral displacement both initially and at latest follow-up. Posterior displacement of the proximal femoral metaphysis should raise concern due to an association with the need for further surgical intervention. These results did not however correlate with outcome.

In conclusion, despite the significant differences noted between DDH and normal hips they did not predict acetabular development or persistent acetabular dysplasia.

Surgical treatment of complex deformities necessitates a detailed appreciation of the complex three dimensional abnormal anatomies involved. Preoperative planning for these complex cases traditionally involves x-ray and computerised tomography (CT). These modalities offer only two-dimensional images to represent three-dimensional anatomy. Advances in digital imaging have allowed three-dimensional reconstructions to be derived from CT images. These greatly improve understanding of complex deformities, but will never be able to replace the intuitive understanding that is gained by handling a physical model.

The Rapid Prototyping technique Selective Laser Sintering (SLS) is used in the industrial setting to manufacture prototype models from Computer Aided Designs (CAD). This technology can be utilised to convert CT images into accurate three-dimensional physical models of the human bony anatomy.

We present the use of SLS modelling to aid in the preoperative planning of complex reconstructive surgery in children. Cases include bladder exstrophy, developmental dysplasia of the hip and reconstruction of a complex elbow malunion.

The models provide invaluable visual and tactile information to the operating surgeon, accurately demonstrating the abnormal anatomy in an easily comprehensible manner. They allow estimation of the magnitude and degree of corrections necessary and evaluation of bony deficiencies.

Accurate and relevant patient chart notes are a key component in successful patient care. Hospital charts also constitute an important medicolegal record. The key to defensibility of at least 40% of medical claims rests with the quality of the medical records. With this in mind, we decided to assess the quality of chart note keeping in our unit. A retrospective review of fifty randomly chosen charts was performed. A scoring system was devised to audit ten key criteria comprising patient details, admission note, daily progress notes, signature clarity, consent form, operation note, post-operative plan, post-operative x-ray review, specification of right or left side and discharge letter. Members of the orthopaedic surgical staff were then informed of the chart review and the nature and purpose of the study was explained in detail. They were also told that there would be another chart audit at some random time over the following three months. Subsequently, a further fifty charts were assessed using the same criteria and scoring system. Overall, charts scored poorly in the areas of patient details, clarity of signatures, post-operative x-ray review and left-right specification. Criteria that scored satisfactorily included admission note, consent form, operation note, post-operative plan an discharge letter. Meticulous hospital notes are vitally important in the day-to-day management of patients for successful continuity of care and also for protection of the medical staff should any adverse outcomes arise. In this litigious society consultants and junior medical staff need to be reminded of the importance of optimal note keeping.

Background The complex ranges from mild epispadias to devastating cloacalexstrophy. Affected babies require multidisciplinary care. The orthopaedic surgeon may assist either directly, in releasing the midline by pelvic osteotomies or indirectly, by advice and treatment of musculoskeletal symptoms related to disturbed mechanics or deformity in the spine, pelvis and lower limbs.

Traditional osteotomies are posterior or horizontal. A technique of an oblique osteotomy from the sciatic notch to the iliac crest has been developed at Great Ormond Street since 1996, along with a system of external fixation. It is undertaken concurrently with urological reconstruction. The system of external fixation is relatively simple compared with other published work.

Methods We reviewed the results of 45 oblique osteotomies performed in conjunction with genito-urinary repair of classical and cloacal bladder exstrophy. Average follow-up was 37 months. Clinical outcome measures were pain, function, continence and normal gait. All radiographs were reviewed and the pubic intersym-physeal diastasis was recorded pre-operatively and on the latest post-operative x-ray. Children were grouped according to the age at the time of osteotomy.

Also children with classical exstrophy were divided into 4 groups on the basis of continence.

The mean post-operative percent reduction in the amount of the original diastasis was determined for all age groups. Comparison of pubic approximation was made between the two types of post-operative immobilisation

Results The majority of patients (42) reported no pain or functional disability. Six cases had a waddling gait pattern and 2 had residual external rotation. All the wounds healed and every osteotomy united.

The average improvement in pubic approximation was 37% for the whole series. Chidren who were older at the time of surgery (18–60 months) were found to maintain better correction over time (76%).

Children immobilised with an external fixator maintained better closure of the pelvis than those treated with plaster cast alone. (51% and 12.2% respectively). Maintenance of pubic approximation was associated with a higher level of bladder continence.

Complications included 3 cases of infection and loosening of the external fixator requiring early removal. There were no neurovascular complications.

Conclusion Oblique pelvic osteotomy is an effective part of the reconstruction bladder exstrophy and compares well with other types of osteotomy.

It is a reliable operation and the technique is applicable to all age groups.

Technique of Oblique Pelvic Osteotomy Oblique pelvic osteotomy is performed by first placing the patient in the supine position, preparing and draping the lower part of the body from the costal margin to the mid-thigh. Intravenous antibiotic prophylaxis is administered and continued for a 24-hour period.

Initially the Urologist will make an infra-umbilical incision then identify and mobilise the anatomical structures intended for their subsequent reconstruction and repair. This wound is then temporarily closed.

The Orthopaedic surgeon will then approach the ilial crest through bilateral oblique incisions made inferior to the anterior superior ilial spine as described for the Salter osteotomy

The interval is developed distal to the anterior superior ilial spine after identification and protection of the lateral femoral cutaneous nerve which is taken medially. After the interval between sartorious and tensa fascia lata are identified the iliac apophysis is split and reflected off the inner and outer ilial crests. The exposure may be improved by also developing the interval between rectus femorus and gluteus medius. Each side of the pelvis is exposed sub-periosteally from the iliac crest extending into the sciatic notch.

A Gigli saw is then passed through the sciatic notch. The line of the osteotomy is from the posterior part of the sciatic notch extending anteriorly and superiorly to exit the iliac crest 2cm posterior to the anterior superior iliac spine (figure 2). The most anterior 1.5cm of iliac crest from the distal pelvic fragment is trimmed to allow closure of the iliac apophysis after rotation.

The size of the half pin utilised is determined by the age of the patient. A baby under 18 months old will have a 3.5mm pin from the AO wrist external fixator frame and an older child over 2 years, a 4.5mm half pin. One half pin is inserted on each side of the pelvis. The half pin is placed in the distal fragment from anterior and lateral to posterior and medial with the tip of the screw just exiting the cortical bone of the medial aspect of the sciatic notch (figure 3a). Consideration of pin placement must take into account rotation of the distal fragment and preventive skin pressure areas. The iliac apophysis is repaired and the skin wounds are closed.

The Urologist completes the reconstruction procedure planned via their infra-umbilical approach.

The final stage involves the medial and superior rotation of both distal pelvic fragments and subsequent closure of the symphyseal diastasis. This position is maintained with the application of an anterior A-shaped frame from the wrist, AO fixation set in the younger infant or the AO pelvic fixator in the older child (figure 3b).

Symphyseal approximation is confirmed intra operatively by palpatation. Bilateral above knee front slabs casts are applied to prevent kicking the hips or knees.

The post-operative management involves pin site care on alternate days. The front slab casts are removed at 3 weeks and the anterior A-frame is removed at 6 weeks after union is confirmed on a pelvic radiograph. Depending on the social situation the children may go home during the post-operative period.

Aim: Advances in digital imaging have allowed three dimensional reconstructions to be derived from CT images which greatly improve understanding of complex deformities. Selective laser sintering (SLS) is used in the industrial setting to manufacture prototype models from Computer Aided Designs (CAD). This technology can be utilised to convert CT images into accurate three dimensional physical models of the human bony anatomy. This SLS modelling was used as an aid in the pre-operative planning of complex pelvic surgery.

Materials and Methods: Standard pre-operative X-ray of the pelvis and a CT scan was undertaken. Using MIMICS software and selective laser sintering, models of these deformities could be made. The cases included bladder exstrophy and a complex developmental dysplasia of the hip with associated femoral head dislocation. The cost of this was comparable with a CT scan or MRI scan.

Conclusion: These models provide invaluable visual and tactile information to the operating surgeon, accurately demonstrating the abnormal anatomy in an easily comprehensible manner. They allow estimation of the magnitude and degree of corrections necessary and evaluation of bony deficiencies.

Introduction: Loss of nutrient supply, seen in disc degeneration, leads to low concentrations of oxygen and glucose in the centre of the disc. Here we investigate the effect of low nutrient concentrations on the metabolism and viability of the nucleus cells.

Methods: Isolated bovine nucleus pulposus cells were cultured for 24–72 hrs over a range of pH levels and glucose and oxygen concentrations. Changes in metabolite concentrations with time were measured in a purpose-built chamber using embedded electrodes, or biochemically; and metabolic rates determined. On completion, cell numbers were counted and viability assessed.

Results: Metabolic rates varied both with oxygen concentration and with pH. At low oxygen (2% pO₂) and low pH (pH 6.2) for example, oxygen consumption rates and lactic acid production rates were 10–30% those in air at pH 7.4. Low pH in air saturated medium, or low pO2 in neutral medium, reduced metabolism but not as drastically. Glucose concentrations in the range 0.5–5mM in contrast did not affect cellular metabolism. Cells could survive with zero oxygen, although metabolism was seriously dimished; but after 24 hours at low (< 0.5mM) glucose, cell death was observed.

Discussion: Regulation of the concentrations of nutrients in vivo is complex, and depends on both supply and demand. Little is known about cellular demand, and studies such as this could give insight into the situation in the disc in vivo and help determine the cellular consequences of a fall in nutrient supply.

Our results, apart from showing the deleterious effects of low nutrient concentrations, also indicate that isolated cells may metabolise differently from cells in the tissue; at low pO₂ we observed a fall in lactate production, the opposite effect to that seen in tissue previously. The mechanism for this difference is as yet unknown.

This poster describes the separation of a pair of conjoined twins, aged 3 months. They were joined at the pelvis, shared a common hindgut and each had bladder exstrophy. The operation to separate them, done over a weekend, involved paired teams of anaesthetists, Paediatric Surgeons and Paediatric Urologists and one Orthopaedic Surgeon.

The surgeons mobilised and divided the hindgut, giving one twin the distal half and the other the caecum and proximal colon. Two Urologists reconstructed the bladder exstrophies.

The orthopaedic contribution was bilateral oblique pelvic osteotomy to allow midline closure, along with extensive hip releases to deal with severe flexion and abduction contractures.

Both twins survived and are thriving. They have little neurological impairment in the lower limbs and therefore have great potential to walk.

Introduction: Complications of homologous blood transfusion include transmission of infection and development of antibodies. Autologous pre-donation, acute normo-volaemic haemodilution and cell salvage have been used to reduce the use of homologous transfusions.

Surgery for spinal deformities often requires blood transfusion. In February 1999, we started an autologous pre-donation programme for children undergoing spinal deformity surgery.

Methods and results: The case records of the first 15 patients who took part in the programme have been scrutinised and data about pre-donation, haemoglobin, pre- and post-operative hameoglobin, blood loss, blood transfusions, use of blood products, and complications related to pre-donation of blood were obtained and analysed. Similar data from case records of 15 patients, who had surgery for spinal deformities before start of the programme, were used as control.

In the autologous pre-donation group, four received homologous transfusion and 11 escaped exposure to homologous blood or blood products. In comparison in control group 14 out of 15 received homologous transfusion. There was no significant difference between the two groups in terms of diagnosis, operating time, postoperative haemoglobin, body weight and age. Mean operative blood loss in autologous group was less (1190 mls) than in that of the control group (1529 mls).

Of the four patients who received homologous transfusion, two were transfused outside the hospital protocol.

Complications from pre-donation of blood occurred in three patients and were minor. They included minor bruising in two and difficult and painful venous cannulation in one.

Conclusion: In our practice autologous pre-donation resulted in avoidance of homologous blood transfusion in three quarters of patients undergoing spinal deformity surgery. By adopting strategies such as acute normo-volaemic haemodilution, cell salvage and strictly adhering to protocols for prescribing transfusion, we believe that the need for homologous transfusion could be obviated except in extreme cases.

The purpose of this study was to audit screening and treatment programmes for Developmental Dysplasia of the Hip (DDH) over a 12-year period from 1989 to 2000 with respect to late presentation and treatment rate and duration.

All babies born in Queen Mary Hospital are clinically screened for DDH by a consultant orthopaedic surgeon. Unstable hips are treated by Pavlik Harness and attend an ultrasound clinic run by an orthopaedic surgeon within 2 weeks. High-risk babies or those with suspected instability can also be referred for ultrasound. Serial ultrasound exams assisted with determining the duration of splintage. Radiographs are taken at 4 to 6 months. Late presenters were identified and analysed.

Over the 12-year period 13 cases of late presenting DDH were identified (0.6 per 1000). Half of these had not been screened. None had ultrasound screening. Our treatment rate was approximately 4 per 1000 live births.

Our screening programme can be improved by increased capture of patients for clinical screening. Ultrasound is a useful tool in managing neonatal hip instability allowing duration of splintage to be tailored to the individual and allows early detection of treatment failure.

Introduction: The intervertebral disc is a significant contributor to back pain, and is thus a tissue that is often examined postmortem. Tissue preservation during storage is of importance both experimentally, for research and teaching purposes, and clinically, for possible use in transplantation. The biomechanical function of the disc after storage has been investigated. However, to our knowledge the biological and metabolic consequences of storage have not been studied. Here we have investigated the effects of storage in the intervertebral disc on glucose, lactate, and cell viability.

Method: A total of 53 discs from 14 bovine tails were obtained within 24 hours of slaughter. Discs were either removed immediately and wrapped in clingfilm or kept in situ, surrounded by muscle. Tissue was stored at 4_C, and samples were taken at 2 hours to 9 days. Disc tissue was analysed for lactate, glucose, and cell viability. Muscle was analysed for lactate. Statistical analysis of data was performed using Student’s t test.

Results: Lactate concentrations in discs stored in tails increased with time of storage, being significantly higher even after 24 hours (p< 0.01). In contrast, lactate levels in isolated discs remained constant. Glucose levels were undetectable in discs, irrespective of storage. Muscle lactate was always significantly higher than disc (p< 0.01). The percentage of live cells fell significantly with storage in situ (p< 0.01).

Discussion: The increase in lactate observed in discs remaining in situ appears to arise from lactate diffusing in from surrounding muscle, as no increase was noted in isolated discs. As would be expected, this high concentration of lactate and low glucose appears to affect cell viability adversely, possibly as a consequence of lowered pH. This change in metabolite concentration and hence cell viability is important to note when considering human postmortem tissue, as it may affect the biological function of the disc.

The aim of the study was to review the role of Magnetic Resonance Imaging of the spine in discitis in the toddler age group (one to three years).

Discitis presents differently in different age groups of children. It is most difficult to diagnose in the uncommunicative non-compliant toddler. The clinical features are often non-specific and laboratory and microbiological tests can be unhelpful. A highly sensitive test is required to aid in making the diagnosis. Although MR Imaging has been used in discitis for several years, we reviewed its actual effectiveness in this specific difficult age group.

At a mean of 21 months at follow-up (range 10 to 40), MR imaging of the disc was variable, with partial recovery after 15 months and complete recovery after 34 months. Routine follow-up MR imaging was not recommended.

We reviewed the role of Magnetic Resonance Imaging in eleven consecutive cases, both at presentation and at a follow-up clinic.

MR imaging was diagnostic in all cases, reduced the diagnostic delay, and often avoided a disc biopsy. It demonstrated any paravertebral inflammatory collection, which helped in determining the duration of the oral therapy given after the initial intravenous antibiotics.

In the reconstruction of the exstrophy/epispadias complex pelvic osteotomy has a role in helping the urologist close the anterior defect thereby improving appearance and helping to achieve continence. In the neonate and infant, we have traditionally used an oblique osteotomy coupled with plastering of the legs until the osteotomy shows signs of healing. Plastering has significant disadvantages in respect of nursing care. We have therefore looked to external fixation in this age group.

In the past year we have used the A.O. wrist fixator to stabilise the osteotomised pelvis of ten babies with bladder exstrophy ranging in age from neonates to two years. All have achieved soft tissue closure with improved appearance. However, because of the foreshortened anterior pelvis in the exstrophy patients, it is not possible to reconstruct to normality. The results to date are promising and the patients remain under follow up.

There is great confusion in the literature on mechano-transduction in osteoblasts. This is partly due to the use of hyper and hypophysiological systems for applying forces to cells. We only find evidence for the role of ion channels at hyper-physiological levels of strain. The cells are far more sensitive to tension than compression indicating that structures within the cell are decisive in determining response and that there is no tensegrity within the cell. Single cell mechanical measurements using an adapted atomic force microscope built in our lab, also does not show any evidence for a tensegrity structure. Analysis of the dimension of stretch and the amount of force needed to activate cells indicates that stretch activated ion channels are not involved as the force required is extremely high in relation to the activation energy of an ion channel. The force required to activate at the mechanosensing system is more in line with the forces generated inside a cell by the actin-myosin structure of several hundred thousand piconewtons.

We find no evidence for any other pathway than a PLC-PKC-Calcium pathway involved in any of the signal transduction pathways, but other pathways are involved in hyperphysiological stretch. One of these induces ICAM-1 and thus can induce inflammatory pathways through cell-cell binding of macrophages and other cells.

Due to the very high energies involved in activating the mechano-transduction pathways we do not see any graviception mechanism of single cells. Indeed many microgravitx flights of 25 seconds duration and a flight of 6 minutes did not show any effect in intracellular calcium. The cellular response to microgravity, if it is not an artefact, is not related to mechanosensing.

This work was supported by the German Space Agency (DLR)

Using the trabecular bone bioreactor (ZETOS) developed in our laboratories we have investigated the formation of bone using the fluorescent bone seeking markers calcein and alizarin red. And the association of bone formation with the increase in stiffness with mechanical loading.

10 mm diameter bone cores 5 mm thick were obtained from the distal radius /ulna of cows obtained at the slaughter house. by precision cutting with diamond saws and keyhole cutters (our pattern) in sterile 7–10°C phosphate buffered saline (PBS) and cultured in a variation of DMEM containing fructose HI GEM.

Results: Loading the bone 30x 4,000μ per day resulted in an increase of stiffness of 35%, by day 30 while the non loaded controls decreased in stiffness. Calcein was added at day 27 to the circulating medium for 4 hours and then fresh medium was circulated. On day 30 alazarin red was circulated through the trabecular bone. The bones were subsequently fixed and embedded in resin and sectioned by classical histological techniques. The difference in distance between the two dyes indicated the amount of bone formation. The mechanically loaded bones showed significant evidence of formation and also significant numbers of active osteoclasts indicating high bone turnover. No evidence of necrosis or cartilage formation was found. Formation in unloaded bones was much reduced and on many areas no active osteoblasts could be observed. This is the first demonstration of bone formation ex vivo after 30 days of culture.

We gratefully acknowledge support by the German Arthrose Foundation (DAH) and the AO in Davos, CH. DJ is a recipient of a Fork award from the AO