Most hospitals have introduced digital radiography (PACS) systems. Accurate pre-operative templating prior to hip arthroplasty requires precise information on the magnification of the digital image. Without this information the benefits of expensive digital templating programs (Orthoview-£10000) cannot be realised.

To determine the magnification of a digital image involves the placement of a “calibration object” at the level of the hip joint. This is unpopular with patients and radiographers alike. We describe a method that requires a single measurement to be made from the greater trochanter to the digital film.

An AP pelvis x-ray was taken of 50 patients with hip replacements. The “predicted” magnification was calculated using the new method. As the size of the head of the prosthesis was known the “actual” magnification could be calculated also. There was no significant difference at 0.05, Wilcoxon T, 2-tail test.

Conventional radiography, which assumes a magnification of 20%, results in errors up to 11%. Templating may therefore predict an incorrectly sized prosthesis. Our method is as accurate as methods using a calibration object whilst being acceptable to patients and staff. Its use should lead to more accurate pre-operative templating prior to total hip arthroplasty

Introduction: Scoliosis surgery involves major blood loss, at times exceeding estimated blood volume.

Aim: To evaluate the effects of implementing blood conservation strategies (including cell salvage, controlled hypotension and anti-fibrinolytic drugs) on transfusion requirements in adult patients undergoing scoliosis correction surgery. To establish a protocol for cross matching of blood.

Study Design: We retrospectively studied 50 consecutive adult patients who underwent scoliosis correction surgery (anterior, posterior or combined) between 2003 and 2007. All patients were anaesthetised by the same anaesthetist who implemented a standard transfusion protocol. Age, BMI, pre and post operative haemoglobin, levels fused, duration of surgery, hospital stay, antifibrinolytics used and blood transfused was noted.

Results: 50 patients with mean age 24.6 years and mean BMI 21.9 kg/m2 were studied. 14 patients had anterior surgery, 19 patients had posterior surgery and 17 had combined anterior and posterior procedures. Mean number of levels fused was 9.5 (6–15) and mean duration of surgery was 284.6 minutes (135–550 minutes). Anti-fibrinolytics were used in 31 patients (62%), Aprotinin in 21(42%) and Tranexamic acid in 10(20%). Mean blood loss in patients who received anti fibrinolytics was 530mls while mean blood loss in the other patients was 672mls. (p< 0.05). Blood transfusion was not required in any of the patients undergoing anterior correction only while 7 patients (41%) undergoing anterior and posterior correction and 3 patients (15.8%) undergoing posterior correction only required blood transfusion. Mean volume of cell saved blood re-transfused was 693.8 mls and mean hospital stay was 9.2 days. Mean pre-op haemoglobin was 13.2 g/dl (10.4–17.4) and mean post-op haemoglobin was 10.7 g/dl (7.7–15). 4 patients (8%) required intra and post-operative blood transfusion while 6 patients (12%) required blood transfusion postoperatively.

Conclusion: Use of anti-fibrinolytics like Aprotinin and Tranexamic acid reduces blood loss in scoliosis surgery. In the current scenario, with Aprotinin no longer available for use, our study would recommend the use of Tranexamic acid alongwith other blood conservation measures.

In our unit we do not have blood cross matched for anterior surgery alone.

Idiopathic anterior knee pain (AKP) is common in adolescents and young adults. Most believe that the origin of the problem lies in the patello-femoral joint. Hamstring tightness has also been attributed as an important cause.

The aim of our study was to compare biometric parameters in patients with idiopathic AKP and controls. We also wanted to assess whether there was a difference in the relative electromyographic (EMG) onset times of the medial and lateral hamstrings.

We prospectively recruited patients with idiopathic anterior knee pain in the age group 11 to 25. Patients, but not the control population, had AP, lateral and skyline radiographs taken to rule out other pathology.

We had 34 patients (60 knees) with a minimum one year follow up. There was no difference in the symptoms of patients who attended physiotherapy as compared to those who did not. Patients with knee pain had significantly more hip external rotation (63 deg) as compared to the control (47 deg) group (p=0.001). Patients also had significantly more hamstring tightness (p=0.04).

Surface EMG was recorded (17 patients and controls each) from the medial and lateral hamstrings during 3 repetitions of a maximal voluntary isometric contraction exercise with the knee at 45° of flexion. The lateral hamstrings contracted 48.7 m.sec earlier than the medial hamstrings in patients as compared to controls.

AKP is a multifactorial and self-limiting disorder. Earlier contraction of the lateral hamstrings may cause tibial external rotation and contribute to the symptoms. Our data suggests that physiotherapy did not significantly alter the course of the condition. We believe that increased hip external rotation may contribute to the symptoms by increasing medial facet stress.

Introduction: Sacroiliac joint (SIJ) is a diarthrodial joint and can often be a source of chronic low back pain complex. We present a percutaneous technique for SIJ fusion and the functional and radiological outcome following the arthrodesis.

Aims and Objectives: To evaluate the functional and radiological outcome following percutaneous technique for SIJ fusion with HMA (Hollow modular anchor-age) screws.

Materials and Methods: 15 consecutive patients operated for SIJ fusion between Sep 2004 and Aug 2007 were included in the study. The diagnosis was confirmed with MRI and diagnostic injections. Pre-operative and post-operative functional evaluation was performed using SF-36 questionnaire and Majeed’s scoring system. Postoperative radiological evaluation was performed using plain radiographs. The Hollow modular anchorage (HMA) screws (Aesculap Ltd, Tuttlingen) packed with bone substitute were implanted percutaneous under fluoroscopic guidance

Results: The study group included 11 females and 4 males with a mean age of 48.7 years. Mean follow-up was 14 months. Mean SF-36 scores improved from 37 to 80 for physical function and from 53 to 86 for general health. The differences were statistically significant (Wilcoxon signed rank test; p < 0.05). Majeed’s score improved from mean 37 preoperative to mean 79 postoperative. The difference was statistically significant (student t test, p< 0.05). 13 had good to excellent results. The remaining 2 patients had improvement in SF-36 from mean 29 to 48. Persisting pain was potentially due to coexisting lumbar pathology. Intra-operative blood was minimal and there were no post operative or radiological complications in any patient.

Conclusion: Percutaneous HMA screws are a satisfactory way to achieve sacro-iliac stabilisation.

Background: Radicular pain has been reported even in the absence of a compressive lesion. It has been postulated that annular tears provide a conduit for pro-inflammatory substances, which can leak around the nerve root causing radiculitis. A link between the side of back pain and the side of the annular tear has been reported.

Objective: To establish whether the side of the annular tear may influence the side of the leg in a non-compressive setting.

Methods and patients: We identified 121 patients from the patients referred to our unit with back and radicular leg pain. The mean age of the cohort was 50 yrs and 49% were male. All these patients were investigated with an MRI scan that demonstrated no compression of the nerve root. We used strict exclusion criteria to exclude the patients with any neural compression, previous lumbar operation, degenerative deformity or an associated pathology such as peripheral neuropathy.

Results: The annular pathology was described as annular tears (47 patients) and non compressive disc bulges (106 patients). The odds ratio for the concurrence of an annular tear causing ipsilateral leg pain is 1.05 and for a non-compressive disc bulge causing ipsilateral leg pain is 2.14

Conclusion: A non-compressive disc bulge is more likey to cause radicular symptoms than an annular tear. Though, both these annular lesions can cause ipsilateral nerve root symptoms.

Introduction: We report on a group of 20 metal-on-metal resurfaced hips (17 patients) presenting with a soft tissue mass associated with various symptoms; these masses we termed pseudotumours. All patients underwent plane radiography; CT, MRI and ultrasound investigations were also performed for some patients. Where samples were available histology was performed.

Methods: All patients in this series were female. Presentation was variable; the most common symptom was pain or discomfort in the hip region. Other symptoms included spontaneous dislocation, nerve palsy, a noticeable mass or a rash. The common histological features were extensive necrosis and lymphocytic infiltration. Fourteen of the 20 cases (70%) have so far required revision to a conventional hip replacement and their symptoms have either settled completely or improved substantially since the revision surgery. Two of the three bilateral cases have asymptomatic pseudotumours on the opposite side.

Conclusions: We estimate that about 1% of patients develop a pseudotumour in the first five postoperative years after a hip resurfacing. The cause of these pseudotumours is unknown and is probably multi-factorial, further work is required to define this; they may be manifestations of a metal sensitivity response. We are concerned that with time the incidence of these pseudotumours will increase.

Total elbow arthroplasty (TEA), as a primary procedure and open reduction and internal fixation (ORIF) have been used to treat complex intra-articular distal humeral fractures in elderly patients. The failure rate after ORIF is high and TEA has often been used as a salvage procedure. Although satisfactory results have been reported after TEA as a primary procedure, there are no publications reporting the results of TEA after failed internal fixation (FIF). In this study we compared the results of patients that had TEA after FIF with those that had had primary arthroplasty (PA). We reviewed the results of 9 consecutive patients who had FIF with 12 patients who had PA. All the operations were performed by one surgeon using the same technique and same prosthesis. Both groups of patients were similar with respect to ages, sex, co-morbidity and hand dominance. The mean follow-up for both groups of patients was 5 years. At final review, patients who had had FIF had a mean Mayo score of 68 and a range of flexion/extension of 90 degrees, there was 1 infection and 1 case of loosening. The PA group had a mean Mayo score of 88 and a range of flexion/extension of 96 degrees, there were no cases of infection or loosening. This study shows the results of TEA are satisfactory either as a PA or after FIF, however the results after PA are significantly better than after FIF.

The Morscher press fit acetabular component is a monobloc cup with the polyethylene bonded directly to a titanium mesh shell. There is little published data on the longevity of the Morscher cup apart from the designer’s series. It has been quite widely used in New Zealand since its introduction in 1993. The aim of this retrospective study was to provide an independent mid-term audit of the results of this cup in the New Zealand population.

A retrospective review was undertaken of all Morscher cups implanted at Dunedin Public Hospital or Mercy Hospital by 5 orthopaedic surgeons between 1994 and 1998 with a minimum follow-up of seven years. Clinical and radiological survey was performed with standardised scoring systems. A new method for measuring linear cup wear was developed due to the unusual geometry of the Morscher cup.

136 hips were replaced in 121 patients during the study period 101 were performed in private and 35 in public. Our follow up ranged from 7 to 11 years (mean 8.69). There were 73 males (85 hips) and 48 females (51 hips). The average age of the patients was 57.5yrs (SO 24.97). Pre operatively the mean Merle d’Aubigne score was 9.4 (SO 4.02) and post operatively it was 17.4 (SO 1.58 (p< 0.0001).

There were 2 early revisions: one at 3 days for instability post-operatively and one for an unrecognised intra-operative femoral fracture. One hip required a two stage revision for deep infection at 3 years. Two hips have been revised for polyethylene wear and osteolysis at 7 yrs and 9 yrs and one hip required bone grafting of a large acetabular osteolytic lesion with retention of the cup. A further 4 patients have significant osteolytic defects and 2 have minor osteolytic lesions.

Wear measurements in the unrevised hips have shown a mean linear wear rate of 0.079mm/yr (range 0.000 to 0.222mm). 33% of these hips have a wear rate of > 0.1 mm/yr and 25% have a wear rate of < 0.05mm/yr.

We have found excellent clinical results with the use of the Morscher cup in this relatively young and active cohort. A small group of patients, however, have shown higher wear rates or osteolysis, and we emphasise the importance of continuing radiological review.

The aim of this study was to compare the results of physical examination and magnetic resonance arthrography (MRA) in the diagnosis of superior labrum anterior posterior (SLAP) lesions of the shoulder. A review of all patients seen in 2005–2006 with an arthroscopically confirmed SLAP lesion was undertaken (n =22). Prior to surgery all patients had been examined prospectively by an upper limb physiotherapy practitioner and had then undergone MRA. All scans were undertaken and reported upon by an experienced consultant radiologist, specialising in musculo-skeletal conditions. A combination of 4 clinical tests were used to diagnose a SLAP lesion, these being O’Brien’s, pain provocation, bicep load and the crank test. To confirm a SLAP lesion a minimum of 2 of the above tests had to be positive. The sensitivity of each test in isolation and in combination and MRA sensitivity was determined and values statistically analysed for significance. The sensitivity of each isolated test was as follows: O’Brien’s = 82%, pain provocation = 86%, bicep load = 55% and the crank test = 68%. Using a combination of 2 or more positive tests was 95% sensitive, whereas MRA had a sensitivity of 64%. Using the McNemar test there was a statistically significant assosciation between positive clinical testing and negative MRA findings in the same patient (p< 0.05). The results would suggest that it may be advantageous to use a combination of physical tests rather than 1 test in isolation when examining a patient with a suspected SLAP lesion. The study would also suggest that even in the absence of radiological findings, in patients with a relevant history and strongly positive clinical signs, arthroscopic assessment may be indicated.

Aim: To assess the ease of use and reliability of PICC lines for the delivery of intravenous antibiotics in children with septic joints.

Method: Over a twelve month period 22 children with septic joints were prospectively recruited. All received open arthrotomy and washout prior to commencing antibiotic treatment. At the time of surgery, a PICC line was inserted. All children were given intravenous antibiotics for two weeks then oral antibiotics for four weeks. Inflammatory blood markers were reviewed regularly. Upon removal of the PICC line the tip was sent for microbiological testing.

Results: All 22 children made a full recovery with a minimum of twelve months follow up (range 12–20 months). All PICC line tips were negative for microbiological culture after 48 hours.

Conclusion: Peripheral cannulation for intravenous access in children can be challenging. Younger children have chubby limbs and often fragile veins. Even with the use of topical analgesics the procedure can be traumatic for a young child. A PICC line inserted at the time of the surgical washout of the infected joint seems an ideal solution. PICC lines are safe, reliable and allow for at least two weeks of intravenous access, avoiding the need for regular re-cannulation of children.

Aim: To study the adequacy of reduction of DDH postoperatively using MRI.

Method: Ten consecutive children with DDH who underwent open reduction and femoral osteotomy using Coventry stainless steel implants were scanned postoperatively.

Results: MRI gave reliable diagnostic information in all cases. The position of the femoral head in the acetabulum was clearly seen, despite artefact due to the metal. The mean scanning time was 3 minutes 45 seconds (range: 2 minutes 20 seconds – 5 minutes 30 seconds) and the total time in the MRI suite was between 7 and 10 minutes. No child required sedation.

Conclusions: The use of MRI scanning has been described after closed and open reduction of the hip in DDH to check hip position but has not previously been reported after open reduction with femoral osteotomy and the use of metalwork. Satisfactory images, comparable time and cost to CT scanning and the lack of exposure to ionising radiation make MRI an appealing method of imaging. We recommend it as the investigation of choice in this patient group.

144 total hip replacements were performed by Swedish Orthopaedic Surgeons at Weston NHS Treatment Centre between 2004–2006, in an attempt to reduce the waiting list in Cardiff. Following concerns regarding the outcome of knee arthroplasty patients, the Welsh Assembly funded a clinical and radiographic review of all hip arthroplasty patients from the same unit.

100 hips were reviewed at a mean follow-up of 24 months. The mean Oxford Hip Score was 30 (range 12–60).

Radiolucencies were seen in acetabular zone 1 in 34, and all 3 zones in 28 hips. Femoral component position was > 4 degrees varus in 41 cases. Medial floor breach with intrapelvic cement was seen in 12 cases. 10 cases had > 1cm leg length discrepancy. There were 3 early dislocations, 1 intraoperative distal femoral fracture, 1 Pulmonary Embolus and 2 superficial infections.

4 patients have received further treatment so far, and 12 have been listed for acetabular component revision for loosening. 1 has been listed for stem revision for symptomatic leg length discrepancy of 2.5cm.

There is an unacceptably high early failure rate in this group of patients. The cost of further investigation and revision surgery far outweighs cost-savings achieved by outsourcing treatment to a distant centre.

The Johns Hopkins University Department of Orthopaedics at the Good Samaritan Hospital, Baltimore, Maryland USA

Introduction: Historically, bone scintigraphy has been advocated as a useful diagnostic tool for patients with suspected osteonecrosis or in screening for multifocal disease. The principle aim of this study was to evaluate the sensitivity of bone scanning relative to magnetic resonance imaging in the diagnosis of osteonecrosis.

Methods: Forty-eight patients presented with suspected osteonecrosis of the shoulder, hip, knee, or ankle. All patients underwent simultaneous (less than three months apart) bone scans and magnetic resonance imaging studies as part of a diagnostic work-up. Histological confirmation of osteonecrosis was obtained for all suspected lesions in the study. The diagnostic yield for each imaging modality was then assessed and compared.

Results: All one hundred sixty-three (100%) histologically confirmed lesions were identified by magnetic resonance imaging, while only ninety-one lesions (56%) were identified by bone scan. There was complete uniformity of bone scans with magnetic resonance images in only 38% of patients (eighteen of forty-eight). Bone scanning identified 72% of lesions (forty-seven of sixty-five) in oligofocal patients (less than two involved joints) compared with 45% of the lesions (forty-four of ninety-eight) in multifocal patients (more than two joints involved). Sensitivity of the lesions was highest for the knee and hip and lower for the shoulder and ankle. Larger and later stage lesions had higher bone scan sensitivity.

Conclusions: The results of this study have demonstrated the low sensitivity of bone scintigraphy for diagnosing symptomatic osteonecrosis. Bone scanning did not detect 44% of the lesions (seventy-two of one hundred sixty-three). This study does not support the use of bone scans as a diagnostic or screening tool for this disease.

Introduction: Cementless total hip arthroplasty has been advocated for osteonecrosis of the femoral head (ONFH) as these patients are generally younger and more active than patients with osteoarthritis (OA). Since introduced in the early 1980’s, there have been several generations of cementless total hip prostheses. This study examined the outcome of the femoral stem of four generations of uncemented total hip prostheses.

Materials and Methods: One hundred and fifty-eight hips in 135 osteonecrosis patients (71 men, 64 women) who had a mean age of 46 years (range, 17 to 83) were included. The total number of prostheses included: PCA™ (77), E Series™ (47), Meridian™ (18), and Citation™ (16) (all Stryker, Mahwah, New Jersey). The mean follow-up was 105.5 +/− 60.8 months (range, 20 to 257 months). As part of an ongoing IRB-approved study, data collected includes Harris Hip (HHS) and QOL scores, re-operations (including revisions), and complications.

Results: The femoral components of 142 cases were not revised. These patients had a mean HHS of 86.3 +/− 13.2 points. Of the 15 revisions (9.6%), the primary reasons were loosening and/or significant osteolysis, but there was one infection and one chronic dislocation. The revisions included 10 PCA™ (13.0%) with a mean time to revision of 85 months (range, 25 to 132); 2 E Series™ (4.3%) with a mean time to revision of 85 months (2 cases in one patient; 68 and 101 months); 2 Meridian™ (11.1%) with a mean time to revision of 193 months (2 cases; 98 and 107 months); and 1 Citation™ (6.3%) with a time to revision of 30 months. The pooled revision rate of the 2^nd, 3rd, and 4^th generation was 5 of 80 (6.3%).

Discussion: There were no significant difference in revision rates between the different generations of uncemented femoral components (Chi Square, p=.433). However, the revision rates for the later generations were lower than the earlier generations.

Previous research suggests knee joint moments and muscle activity during walking are altered in patients with anterior cruciate ligament (ACL) deficiency and in patients with medial compartment knee osteoarthritis (OA). The objective of this study was to compare knee joint flexion and adduction moments and the extent of quadriceps-hamstring muscle co-contraction before and one year after combined simultaneous ACL reconstruction and high tibial osteotomy (HTO).

Eighteen patients (three females, fifteen males; age = 40 ± 8 yrs.; BMI = 28.8 ± 5.77) with ACL deficiency and OA affecting primarily the medial compartment of the knee underwent ACL reconstruction (hamstring autograft) and medial opening wedge HTO procedures during a single operation. All patients completed pre-operative and one-year postoperative quantitative gait assessments. Three-dimensional kinetic and kinematic data were collected during self-paced walking and used to calculate the peak external flexion and adduction moments about the knee. Electromyographic (EMG) activity was collected from the hamstrings and quadriceps and used to calculate the co-contraction ratio. Peak moments and co-contraction ratios were compared pre and postoperatively using paired t-tests.

The peak knee flexion moment decreased from 2.31 ± 1.14 to 1.33 ± 0.73 %BW*ht (p=0.001); mean decrease = 0.98 %BW*ht (95%CI: 0.49–1.47). The peak knee adduction moment decreased from 2.81 ± 0.62 to 1.69 ± 0.61 %BW*ht (p< 0.001); mean decrease = 1.12 %BW*ht (95% CI: 0.80–1.43). The quadriceps-hamstring co-contraction ratio decreased from 0.82 ± 0.14 to 0.72 ± 0.18 (p=0.056); mean decrease = 0.10 (95% CI: −0.003 – 0.21).

The present findings suggest that combined simultaneous ACL reconstruction and HTO significantly decreases knee flexion and adduction moments during walking. Although the present findings suggest that the quadriceps-hamstring co-contraction ratio also decreases, future research with more patients is required to confidently evaluate potential changes in muscle activity. These findings are consistent with an overall reduction in dynamic knee joint load.

Purpose: Subject-specific computational models of anatomical components can now be generated from image data and used in the assessment of orthopaedic interventions. Whilst such models are becoming more commonplace, there are few studies that have investigated the effects of element size or the level of morphological detail that is required to model complex hierarchical structures such as trabecular bone [1,2]. The purpose of this study was to investigate the modelling of the mechanical properties of a trabecular-like material under compression, and in particular to evaluate the relationship between the grey-scale dependent density, determined from microCT, and the elastic modulus at different levels of mesh density.

Materials and Methods: A specific open cell rigid foam (pcf 7.5, Sawbone, Sweden), with a porosity over 95% and cell size between 1.5 and 2.5 mm, was chosen to represent human cancellous bone. Five cylindrical specimens (24 mm diameter, 19 mm height) were compressed under a maximum displacement of 0.35 mm in a materials testing machine. All the specimens were imaged by microCT (ƒÝCT80, Scanco Medical, Switzerland) before the test to provide the geometry and greyscale distribution. Corresponding finite element models of each specimen were generated using proprietary software (ScanFE, Simpleware, UK) with an element size of 1.5 mm. The elastic modulus of each element was based on the image greyscale using a conversion factor that was determined, through trial-and-error, by matching the predicted displacement with the experimental measurement in the linear region (> 0.2 mm). For each specimen, models of higher and lower mesh densities were constructed by down-sampling the microCT output to different levels. The smallest element size was limited to 0.5 mm due to computational restrictions, however a smaller 8 mm cube of the material was also analysed, with element sizes down to 0.25 mm.

Results: From the experimental tests, the mean apparent elastic modulus of the specimens was found to be 15 MPa, as compared with 18 MPa specified by the manufacturer. For the computational models, the predicted elastic modulus of the whole specimen models was found to decrease with decreasing element size. In particular, there was a large drop in the predicted values when the element size was of the same order as the cell size. With larger elements, the results indicated some convergence and there was reasonable agreement with the experimental results. For the cube model with smaller element sizes, the predicted moduli values again appeared to converge as the element size was reduced to 0.25 mm.

Conclusion: The results of this study show that the optimum conversion factor from an image greyscale value to an elastic modulus varies with element size. If the finite element method is to be used effectively to model bone, then the mesh size must either be sufficiently large to use a continuum approach or sufficiently small to capture the behaviour of the individual trabeculae. Different conversion factors will be required to determine the material properties from the image greyscale in each case.

Bone Tissue Engineering Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD 4059, Australia.

Osteophytes are the most remarkable and consistently distinct feature of osteoarthritis (OA). Their formation may be related to pluripotential cells in the periosteum responding to stimulus during OA. This study aimed to isolate stem cells from osteophyte tissues, and characterise their phenotype, proliferation and differentiation potential, and immuno-modulatory properties.

Osteophyte derived cells were isolated from five osteophyte tissue samples collected during knee replacement surgery. These cells were characterised by the expression of cell surface antigens, differentiation potential into mesenchymal lineages, growth kinetics and modulation of allo-immune responses.

Multipotential stem cells (MSCs) were identified from all osteophyte samples namely osteophyte derived MSCs (oMSCs). The surface antigen expression of oMSCs was consistent with that of mesenchymal stem cells, such as lacking the haematopoietic and common leukocyte markers (CD34, CD45) while expressing those related to adhesion (CD29, CD166, CD44) and stem cells (CD90, CD105, CD73). The longevity of oMSCs in culture was superior to that of bone marrow derived MSC (bMSCs), and they readily differentiated into tissues of the mesenchymal lineages. oMSCs also demonstrated the ability to suppress allogeneic T-cell proliferation, which was associated with the expression of tryptophan degrading enzyme indoleamine 2,3 dioxygenase (IDO).

Our results showed that osteophyte derived cells had similar properties to mesenchymal stem cells in the expression of antigen phenotype, differential potential and suppression of allo-immune response. Furthermore, when compared to bMSCs, oMSCs maintained a higher proliferative capacity, which may offer an alternative source for therapeutic stem cell based tissue regeneration.

Introduction: Morton’s neuroma is a common cause of foot pain. For this study, we assessed the efficacy of a series of sonographically guided alcohol injections into the lesion.

Method: One hundred and one consecutive patients with Morton’s neuroma were included in this prospective series. An average of 4.1 treatments per person wee administered, and follow-up images were obtained at a mean of 21.1 months after the last treatment (range, 13–34 months).

Results: Technical success was 100%. Partial or total symptom improvement was reported by 94% of the patients, with 84% becoming totally pain-free. The median visual assessed pain score decreased from 8 before treatment to 0 after treatment (p< 0.001). Transitory increased local pain occurred in 17 cases (16.8%). There were no major complications. Thirty patients underwent sonography at 6 months after the last injection and showed a 30% decrease in the size of the neuroma.

Discussion and Conclusion: We conclude that alcohol injection of Morton’s neuroma has a high success rate and is well tolerated. The success rate is acceptable at 84% whilst being associated with a low morbidity. The treatment avoids surgery and allows continued mobility with patients being able to weight bear and perform their usual activities of daily living. We advocate reserving surgical management for non-responders.

Introduction: In the evaluation of various treatments that may have an effect on bone, there are certain inherent difficulties in selecting an appropriate outcome measure to determine whether a specific treatment is efficacious. This is particularly true for clinical studies.

Methods: Using Pubmed, a service of the U.S. National Library of Medicine that searches MEDLINE and other life science journals for citations of biomedical articles, a review of the current instruments used for outcome measures relating to osteonecrosis and bone blood flow was conducted. Abstracts from previous ARCO meetings were also reviewed.

Results: For the treatment of osteonecrosis, most outcome measures have focused on pain relief, surgery or need for surgery, disease progression (advancing stage), and change in lesion size. The first three options may be influenced by investigator bias and knowledge/experience. The last option may also be influenced by the technique used.

Imaging techniques continue to gain in sophistication. Gd-enhanced MRI can be used to assess perfusion of the diseased tissue. Doppler ultrasonography has also been used to estimate blood flow noninvasively. Near Infrared Spectroscopy (NIRS) can be used to measure tissue oxygenation.

While there has been recent interest in using biomarkers or genetic markers in the diagnosis and analysis of disease progression, more research is needed to determine the sensitivity and specificity of these techniques with respect to osteonecrosis.

Conclusion: Although there are a number of tests that can be used to evaluate the effect of a specific treatment on osteonecrosis, the definitive assessment will likely remain whether the disease progresses to the point that major surgery (resurfacing, vascularized fibular grafting, total joint replacement, e.g.) is required to relieve pain and restore function.

Introduction and aims: Familial aggregation of low back pain (LBP) symptoms has been described. However, this may be due to genetic factors or common exposure to environmental factors. This study evaluated the relative contribution of genetic and environmental factors to childhood LBP.

Methods: Data was collected from 1995 to 1998 from a national sample of 1790 Finnish twins aged 11-years. A validated pain questionnaire was used to assess LBP pain. Information was also collected on children’s perception of parent-child relationships, parenting behaviours and home environment. In addition, children were asked about various sedentary and active life-style activities. Variance components for genetic and environmental factors were estimated by using biometric structural equation modelling techniques.

Results: The prevalence of LBP at least once a month was 15.7%, and at least once a week was 6.7%. There was small difference in pairwise similarity of LBP between monozygotic and dizygotic pairs, suggesting little genetic influence. LBP was not associated with either sedentary or active lifestyle activities, but was strongly associated with children’s unsatisfactory perception of the following: home environment (p< 0.001), parenting behaviours (Spearman rho = 0.12, 95% CI 0.06–0.18), relationship with mother (p=0.02) and father (p=0.04). Of the total variance in LBP, 41% (95% CI 34 to 48) could be attributed to shared environmental factors within families; and 59% (52 to 66) to unshared environmental factors.

Conclusion: Genetic factors seem to play a very minor role in LBP in 11-year-old twins. Rather than being related to various aspects of lifestyle activities, childhood LBP is best predicted by children’s perception of home environment and family functioning.

Purpose: To alert the Orthopaedic fraternity that smoking needs to be considered in the Paediatric population and highlight it’s adverse effect on bone healing index.

Method: During assessment of Paediatric patients who had undergone limb reconstruction surgery, a sub-population was found to have a prolonged time to consolidation of the regenerate to norm. Screening for contributing factors, we were surprised to learn that this subgroup were active smokers. Revisiting their radiographs, it was felt that the quality of the regenerate appeared to differ from non-smokers.

Results: We identified 12 patients who were active smokers. 2 also had parents who smoked. They all exhibited a prolonged time to regenerate consolidation. We calculated their bone healing indices to compare with non smokers and found significant differences.

Conclusion: Smoking has adverse effects on bone healing in children as well as adults. We have drawn up an advise sheet to make patients and their parents aware of the adverse effects of active and passive smoking on bone healing.

Introduction: Sequential staged distraction with fixed rate and rhythm, alternative compression and distraction is well described in the literature to treat non-unions. However we looked the union in established non-unions of tibia using one stage distraction without further manipulation at the fracture site maintaining the stability.

Materials and Methods: 12 patients with established tibial non-unions were referred during the period of 2001–2005. 2 cases were infected non unions. All patients were symptomatic and exhibited deformity at the non-union site. Ten males, two females were in the study group with a mean age of 39.2 years. The location of non-union was distal 1/3 of tibia in 8 cases and 2 cases of proximal and middle 1/3. External fixation was used to acutely distract the fracture (one stage) and tension the soft tissues to attain fracture stability. Infection at the fracture site required further operative debridement. Regular followup with radiographs to assess the union.

Results: Osseous union was achieved in all the cases at an average time period of 17.2 weeks. There was no recurrence of osteomyelitis in the infected cases following secondary debridement. All the patients were pain free and fully mobile without aid at review.

Conclusion: We concluded that acute distraction osteogenesis produces fracture union in selected established cases of non union. This method can be used to obtain impressive gains in the lengths of the long bones. Bone is uniformly produced regardless of the location of the non union. This is more patient compliant, effective and relatively easy to perform.

AIM: The purpose of this prospective study was to asses the outcome of antegrade intramedullary wiring of displaced distal end of fifth metacarpal fracture in skeletally immature. Intramedullary wiring for fracture metacarpals have been well described in the literature. Retrograde wiring for neck of metacarpal fractures have been associated with limitation of extension at metacarpo-phalangeal joint due to involvement of gliding extensor mechanism. Foucher described ‘Bouguet’ osteosynthesis with multiple wires for metacarpal neck fracture which can be technically demanding in small bones of children. We describe an antegrade wiring using a single bent K-wire at the tip for reducing and stabilising displaced metacarpal neck fracture by rotating 180 degree after crossing fracture site, a method similar to Methaizeau technique for stabilisation of displaced radial neck fractures using nancy nail.

METHOD: Between 2000 to 2006 we treated 9 boys with displaced distal end of fifth metacarpal fracture +/− rotational deformity of little finger using above technique. All of them had closed injuries and the indication for surgery was rotatory mal-alignment or fracture angulation more than 40 degrees. The assessment involved a clinical and radiological examination. The mean age was 13 years. The mean follow-up was 15 months.

RESULTS: All fractures healed in anatomical alignment. There was no loss of active or passive movement of the little finger metacarpo-phalangeal joint or weakness of grip strength in any children. All children returned to pre-injury activity level within 4–6 weeks. There were no complications.

CONCLUSION: Early results of treating displaced little finger metacarpal neck fracture in children using antegrade intramedullary wire are encouraging.

Aim: Spinal stenosis is a known entity in achondroplasia and a need for screening for the symptomatic children was identified in a tertiary limb reconstruction service. The aim of this study was to evaluate whether clinical and radiological imaging would identify the at risk group.

Materials and methods: 205 achondroplastic children were treated at our service in the last 20 years. A prospective clinical screening programme for spinal stenosis which also included the MRI imaging of entire spine was however introduced only in 1996. 26 patients were available for this study. Case notes were reviewed for clinical symptoms and neurological signs. MR images were assessed for stenosis especially at Cervico medullary junction and lumbar level. Canal diameters were measured at all spinal levels from CMJ to lumbo-sacral junction. Neurosurgical interventions were recorded. An attempt was made to identify high risk factors that required surgical intervention.

Results: Delayed milestones were observed in 7 patients. Positive history of back pain or radicular pain was obtained in 10 whereas 10 patients had symptoms of neurogenic claudication. Brisk reflexes and clonus were consistent findings. Severe foramen magnum narrowing was observed in 23 patients and 13 showed ‘kinking’ or ‘pinching’, suggesting severe compression. Of the 17 patients seen by neurosurgeons 6 required single or multiple surgical decompressions. Ventriculo-peritoneal shunt was inserted in 4. 5 children required CMJ decompression and one required lumbar canal decompression. There was a 7 mm difference in AP diameter measured on MRI at CMJ between the two non operated and operated groups. Female patients with delayed milestones and CMJ narrowing to less than 25 mm were identified as high risk.

Conclusion: The cause of increased morbidity and mortality in young achondroplasts is attributable to severe CM compression. Sudden death can occur by acute or gradual progressive encroachment of respiratory centre at medulla oblongata. We were able to identify symptomatic patients early before developing myelomalacia and cord changes by screening all symptomatic children with achondroplasia. We propose that female gender, especially with delayed milestones as another high risk factor. We stress upon the importance of developing a nationalised selective screening programme with guidelines in specialist orthopaedic and joint multi-disciplinary Skeletal Dysplasia clinics.

Introduction: Ankle fractures accounts for 25% to 38% of all physeal fractures. An accurate diagnosis is the key to the appropriate management of these fractures. Traditionally the management decisions have been based on x-ray findings. We have used computed tomograpy (CT) scans in additon to x-rays in the management of these fractures.

Objective: To determine the usefulness of computed tomograpy (CT) scans in the management of ankle fractures in children.

Materials and Methods: Between 2001 to 2005, 53 patients with ankle fractures who were managed in our unit had CT scans in addition to plain radiographs. The mean age was 12.3 years (+/− 2.1). The radiographs were reviewed by senior paediatric orthopaedic surgeon who classified the fractures and formulated treatment plans (operative/non-operative). The CT scans were then reviewed by the respective surgeon and a similar exercise undertaken. A Radiologist confirmed that the fractures were classified accurately.

Results: In 47% (25 fractures) the x-ray diagnosis/classification tallied with the CT scans whilst in 53% (28 fractures) the CT scans showed the fractures were more extensive/serious than noticed on the x-rays. The management was changed in 34% after reviewing the CT scans, In 9 from operative to non-operative treatment and in the other 9 from non-operative to operative treatment.

Conclusion: We have found CT scans to be more useful than plain radiographs in making an accurate diagnosis of ankle fractures in children and thus planning appropriate management.

Introduction: Interest in hip resurfacing has recently been renewed by the introduction of metal-on-metal designs; it is being increasingly used for young patients, with over 30,000 implanted worldwide. The 5 year clinical results appear promising, but there are no long term data available. Radiostereometry (RSA) measures of implant migration have been able to predict implant failure; specifically large and continuous migration predicts aseptic loosening. We present the results of a five year RSA study examining the migration of the Birmingham Hip Resurfacing (BHR).

Methods: Twenty-four subjects with primary OA were implanted with the BHR device and with bone markers for RSA. RSA measurements were taken at 3, 6, 12, 24 and 60 months. The migration of the head and the tip of femoral component were measured in 3D.

Results: Preliminary analysis showed that the total 3D migration of the head and tip over five years was 0.32mm and 0.23mm respectively.

Discussion: A distal migration of more than 0.4mm over 2 years increases the likelihood of failure in conventional stems. The total migration of the BHR was approximately 0.3mm over a five year period, significantly less than cemented THR devices. The device is stable and this is promising for long-term survival.

Aim: To investigate and compare the effects of two types of LCS total knee arthroplasty on joint proprioception and range of motion.

Methods: 47 patients were randomised to receive either a LCS AP glide or Rotating platform prosthesis. Clinical scores (Oxford knee score, American knee society score, EuroQol), range of motion and proprioception were assessed prior to and at 3,6, and 12 months after the operation. Proprioception was assessed in terms of absolute error angle (mean difference between the target angle and the response angle). Knee angles were measured in degrees using an electromagnetic tracking device, Polhemus 3Space Fastrak that detected positions of sensors placed on the test limb. Student’s t-test was used to compare the mean of two groups (with a level of significance of p < 0.05).

Results: Both groups were comparable in terms of pre-operative range of motion, oxford knee score, American knee society score, EuroQol score and proprioception. There was statistically significant improvement in the Oxford knee score, AKSS and EuroQol score in both groups (p< 0.001), but there was no difference between the groups with respect to these parameters. There was improvement in the proprioception (reduction in absolute error angle) in both groups though this was not significant statistically (p> 0.05).

Conclusions: We did not find significant difference between AP glide and RP LCS knee arthroplasty in terms of improvement in proprioception and range of motion.

Anterior Lumbar Interbody Cages are used to recreate the lumbar lordosis in scoliosis surgery as anterior instrumentation is usually kyphogenic. We report two cases in which an anterior release was performed and interbody cages were used.In both these patients the cage was displaced anteriorly by an incorrectly positioned pedicle screw during posterior instrumentaion. In one case the cage was retrieved and correctly repositioned from the back using a TLIF approach, in the other this was noticed only post-operatively and patient needed another anterior surgery. We recommend a lateral Image Intensifier screening for combined anterior and posterior cases in which anterior cages are used in addition to posterior pedicle screws to prevent this complication.

Objective: To assess the correlation between the side of the annular pathology and the radicular symptoms, in the absence of a compressive root lesion.

Materials and Methods: 121 patients underwent MRI scan fro axial back and radicular symptoms. The mean age was 49.9 yrs (24–80). The sex distribution was equal. We excluded the patients that had a compressive lesion, previous operations, spinal deformity, spondylolyses, an underlying pathology (tumour, trauma or infection) or a peripheral neuropathy. Annular pathology was documented as annular tear or a non-compressive disc bulge with its location and side. We also recorded marrow endplate changes and facet arthrosis.

Results: Bilateral radicular symptoms were reported in 16 (13.2%): right side in 33 (27.3%) and left in 47 (38.8%) patients. Additionally, 82 patients (67.8%) had axial back pain. 33 patients (27.3%) were noted to have a right sided annular pathology (tear or bulge) and 72 (59.5%) had a left sided annular lesion. 21 patients (17.4%) had a central annular tear and 43 (35.5%) had a generalised disc bulge. 14 patients (11.6%) with right sided symptoms also had annular pathology, while 38 patients (31.4%) with left sided symptoms had a left sided annular lesion. There was no statistical correlation between the side of symptoms and the side of the lesion (r = −0.00066, p=0.994), any particular annular pathology (annular tear r=0.085, p=0.35; disc bulge r-0.083, p=0.36). There was no correlation between the axial back pain and the annular pathology (r=0.004; p=0.97) and facet joint or marrow end plate changes (r= −,29, p=0.76).

Conclusions: Although annular pathology can cause the radicular symptoms, our results suggest that they do not influence the side of the symptoms.

Objective: To assess the temporal geometric sagittal profile changes on serial radiographs of fractures of the thoracic and thoraco-lumbar spine.

Materials and methods: We have included 103 patients with thoracic or lumbar fractures were treated at our unit between June 2003 and May 2006. The patients were suitable for non-operative treatment. The mean age of the cohort was 46.9±2.4 (16–90). The sex distribution was equal. 94 patients had a single level lesion. 19 fractures were in the thoracic spine; 64 in the thoraco-lumbar (T11-L1) and 29 between L2 and L5. The radiographs were scored using the AO classification by 2 senior orthopaedic trainees. The radiographs were analysed at the Spine Research Laboratory. The results were computed using Stat, a statistical software.

Results: The changes were assessed over a mean period of 5.6 mo (range 1–49 mo; 95% CI 4.1–7.1 mo). Weighted kappa score of 0.58 was computed for the primary fracture type and 0.22 for the fracture sub-types. The inter-observer rater agreement was similar to that reported in literature. 7 patients showed a significant collapse. We report the association between the fracture types and the extent of collapse. We have also assessed the association between the medium to long term symptoms, the fracture types and the extent of collapse at the fracture sites and the adjacent disc.

Conclusion: Some fracture sub-types are more likely to collapse and cause long term symptoms. Identifying these fractures at the outset would help clarify surgical indications.

Objective: To do assess changes in patients’ symptoms and the operative plan.

Materials and methods: 147 patients on a spinal surgery waiting list were assessed at a mean wait of 15.8 ± 1.3 months. 89 (61%) were male and 58 (39%) were female at a mean age of 49.7 yrs (16–78). 123 patients had a degenerative condition (20 cervical; 03 lumbar); 20 patients were seen for scoliosis; 2 with a post-traumatic kyphosis and 1 each with ankylosing spondylitis and a psudarthrosis.

Outcomes assessed: Changes in patients symptoms; changes from the initial operative plan when listed; requirement for re-imaging due to the wait.

Results: 31 patients reported improved symptoms at the re-assessment, while 96 were worse off and 20 were unchanged. 137 had axial pain when listed which changed to 116 at review (p=0.0018). 130 had radicular pain when listed which improved to 80 on re-assessment (p< 0.0001). However 19 reported an increase in the axial and 17 in the radicular symptoms. 71 patients (48.3%) required to be re-imaged at the re-assessment due to changes in the clinical picture. 42 patients received the procedure as originally listed. 30 patients were taken off the list, 24 received a different operation, and 38 had an interim or a definitive needling procedure while 13 await a re-assessment.

Conclusions: On the basis of the observations on our cohort, 1 in 5 operations were cancelled; 65% had an increased severity of the symptoms and just 1 in 3 patients were operated as planned while 48% required re-imaging. A long wait inevitably leads to changed symptoms and a review of these patients is mandatory. The review and the re-imaging adds to the burden on the already over-loaded system.

Pedicle screw fixation has become the norm for the surgical correction of adolescent idiopathic scoliosis (AIS), with much biomechanical research into different types of rod screw constructs. The senior authors have experience using a monoaxial screw only construct in the correction of AIS since 2003 and the polyaxial screw only construct since 2005.

We retrospectively reviewed our experience in the first ten patients with AIS using the polyaxial system and compared this against 18 patients who had been corrected using the monoaxial system. Table I shows our results, expressed as mean and ranges or means ± SD for the main thoracic and lumbar curves.

Our early results show that the polyaxial system produces similar correction of both the thoracic and lumbar curves as compared to the monoaxial system in the immediate post-operative period. Though the absolute values for the lumbar curves differ between the two groups the percentage correction shows no statistical difference.

Introduction: Sacroiliac joint pathology can contribute to lowback pain and sciatica. Its frequency and significance is controversial.

Aims: The purpose of this study is to evaluate the incidence and clinical significance of positive SI joint pathology on MRI scans.

Methodology: 353 MRI reports and scans carried out over a one year period for backpain and sciatica were reviewed. Demographic data and clinical notes of patients who had positive SI joint pathology on MRI scans were analysed. Correlation between clinical suspicion of SI joint pathology and MRI findings was studied.

Results: 12 scans showed pathology in the SI joint, an overall incidence of 3.3%.8(66%) were males and 4(33%) females. Only 4(33%) of these patients had Plain Film abnormality. Average age of 41.2 years (33–54). One patient was known case of Ankylosing Spondylitis. Other positive pathology included oedema, sclerois and bridging osteophytes. Clinicians requested inclusion of SI joint in 43 patients. 8 of these were positive, an incidence of 18.6%. In 130 patients, the SI joints were imaged as routine. This yielded positive pathology in 4 patients (3%).

Conclusion: Our study concludes that 18.6% of patients who are suspected to have SI joint involvement clinically have positive pathology on MRI scans.

Routine inclusion of imaging of the SI joint as part of lumbosacral spine MRI for back pain and sciatica shows only 3% positive results.

SI joint should be imaged only if clinically suspected.

Introduction: Loads acting on scoliotic spines are thought to be asymmetrical and involved in progression of the scoliotic deformity. Abnormal loading patterns could lead to changes in bone and disc cell and activity and hence to vertebral body and disc wedging. At present however there are no direct measurements of intradiscal stresses or pressures in scoliotic spines.

Methods: Stress profilometry was used to measure horizontal and vertical stresses at 5mm intervals across 25 intervertebral discs of 7 scoliotic patients during anterior reconstructive surgery. Identical horizontal and vertical stresses for at least two consecutive readings defined a region of hydrostatic pressure. Results were compared with similar stress profiles measured during surgery across 10 discs of 4 spines with no lateral curvature and with data from the literature.

Results: Profiles across scoliotic discs were very different from those measured across normal discs of a similar age. Hydrostatic pressure regions were only seen in 16/25 discs, extended only over a short distance and were displaced towards the convexity. Mean pressures were significantly greater (0.24MPa) than those measured in other anaesthetised patients (< 0.06 MPa). A stress peak in the concave annulus was a common feature (13/25) in scoliotic discs. In 21/25 discs, stresses in the concave annulus were greater than in the convex annulus, indicating asymmetric loading in these anaesthetised, recumbent patients.

Conclusions: Intradiscal pressures and stresses in scoliotic discs are abnormal even in the absence of significant applied load. Disc cells respond to changes in pressure, hydration and deformation by altering matrix synthesis and turnover in vivo and in vitro. Hence, whatever the cause of the abnormal pressures and stresses in the scoliotic discs, if present during daily life, these could lead to disc matrix changes and especially if asymmetrical, to disc wedging and progression of the scoliotic deformity.

Work supported by Fondation Cotrel

Aim: To assess if commonly used scoliosis instrumentation activates metal detectors at airport security gates.

Methods: 20 patientswho had travelled by air following scoliosis surgery were included. The type of instrumentation, number of journeys, body mass index and whether the alarm was triggered off by the airport security detector was recorded. We asked the patients opinion regarding provision of documentary evidence of surgery.

Results: 10 patients had posterior instrumentation, 5 patients -Paediatric ISOLA,4 patients had anterior instrumentation and one patient, anterior and posterior instrumentation. 12 patients (60%) had travelled more than four times by air following surgery corresponding to 48 passes through an airport archway detector.5 patients out of 20 had set off the alarm while passing through the metal detector everytime of which 4 had posterior instrumentation and 1 anterior instrumentation. None of the patients with ISOLA instrumentation set of the alarm. Two patients had set off the alarm every time they passed through the metal detector and both of them had posterior instrumentation. 14 patients(70%) suggested that we should provide documentary evidence of surgery to avoid delays in the airport security check. 25 % of patients set of the metal detector alarm following scoliosis instrumentation.

Conclusion: Patients with posterior instrumentation are more likely to set off the alarm compared to patients with ISOLA instrumentation. It is important to be aware that scoliosis instrumentation can activate airport archway detectors in our present security climate and to provide documentation to patients in order to avoid embarassment and delays.

Introduction: Scoliosis Nursing service was introduced at the Cardiff Spinal Unit in 2003 as part of a multi-disciplinary team to improve quality of care for the patients and their families.

Background: This nurse is a point of contact at pre-admission and discharge. She co-ordinates the peri operative care and liases with other team-members including physiotherapists, occupational therapists and dieticians. Information regarding type of surgery, pain management, wounds/dressings, investigations is offered.

Aims and Objectives: To assess patients’ and families perception and satisfaction with the various aspects of care provided by the Scoliosis Nurse.

Methods and Materials: From 2005 to 2006, 30 consecutive patients and families who had seen the Scoliosis Nurse filled a questionnaire. 25 questionnaires were completed. Response was collated by an independent observer.

Results: All (100%) respondents felt that the presence of a nurse in clinic was beneficial. (100%) reported that they had received adequate information and literature. 66% of the patients felt a pre admission ward visit would be beneficial. 63% felt that further information about discharge and aftercare would be helpful.

Conclusion: Thus the Scoliosis Nurse was perceived to be beneficial by the patients and the family. Based on the abovefeedback the patient Information booklet has been updated.

Paravertebral anaesthesia is a particularly effective, safe and reliable option in scoliosis patients undergoing anterior release in whom percutaneous epidural placement may be difficult to perform. A recent systematic review and meta-analysis of randomized trials has demonstrated that whilst paravertebral block and thoracic epidural insertion provide comparable pain relief after thoracic surgery, paravertebral block placement is associated with a better side effect profile, including a reduction in pulmonary complications, hypotension, nausea and vomiting and urinary retention. We describe a case of a 16 year old female patient who underwent staged correction of her thoracolumbar scoliosis. A paravertebral catheter was inserted under direct vision for continuous infusion post operative analgesia following the anterior release. 48 hours after surgery a swelling was noted in the groin, which was confirmed with ultrasonography as a fluid collection. The swelling resolved upon removing the paravertebral catheter. This suggests that it was caused by the local anaesthetic fluid tracking along the psoas muscle. Retroperitoneal infections, venous thrombosis, femoral hernia, femoral artery aneurysm and inguinal lymphadenopathy are other differentials. Ultrasonography was a fast and sensitive investigation to rule out these differentials and determined that fluid communicating with the abdominal cavity was the cause for this swelling. The infused local anaesthetic had tracked down into the femoral triangle and the swelling resolved upon cessation of the infusion.

Aims: The aims of our study were:

to measure the total metal content in cell saver blood recovered during revision hip arthroplasty,

Materials and methods: We analysed the levels of metallic debris and metal ions in cell saver blood in nine patients undergoing revision hip replacement. Using inductively coupled plasma mass spectrometry (ICP-MS), the levels were measured for titanium, aluminium, vanadium, chromium, cobalt, nickel and molybdenum. The metal ion levels were analysed using a dilution technique and the total metal content levels (particulate debris and ions) were analysed with a digestion technique.

Results: Significantly higher levels of metal ions and metal debris were found in the pre-processed blood compared with the processed blood (after centrifuging and washing). The ion levels in the processed blood were not high enough to cause a significant increase in the patients’ immediate post-operative blood ion levels when compared with pre-operative levels.

Discussion: There are markedly elevated levels of metal ions and particulate metal debris in the blood salvaged during revision total hip arthroplasty. The processing of the recovered blood in a commercial “cell saver” significantly reduces the total metal load that is re-infused. Re-infusion of salvaged blood does not result in elevated metal ion levels in the immediate post-operative period.

Introduction: Painful anterior vertebral wedge “fractures” can occur without any remembered trauma, suggesting that vertebral deformity could accumulate gradually through sustained loading by the process of “creep”. If the adjacent intervertebral discs are degenerated, they press unevenly on the vertebral body in a posture- dependent manner, producing differential creep of the vertebra. We hypothesise that differential creep due to sustained asymmetrical loading of a vertebral body can cause anterior vertebral wedge deformity.

Materials And Methods: Eleven thoracolumbar motion segments aged 64–88 yrs were subjected to a 1.5 kN compressive force for 2 hrs, applied via plaster moulded to its outer surfaces. Specimens were positioned in 2° flexion to simulate a stooped posture. Reflective markers attached to pins inserted into the lateral cortex of each vertebral body enabled anterior, middle and posterior vertebral body heights to be measured at 1Hz using an optical tracking device. Compressive ‘stress’ acting vertically on the vertebral body was quantified by pulling a miniature pressure transducer along the midsagittal diameter of adjacent discs.

Results: Elastic deformation (strain) was higher anteriorly (−2018 ± 2983 μ strain) than posteriorly (−1675 ± 1305 μ strain). Creep strain (−2867 ± 2527 μ strain) was significantly higher anteriorly (p< 0.05) than posteriorly (−1164 ± 1026 μ strain), and was associated with a higher compressive stress in the anterior annulus of the adjacent disc. Non-recoverable creep deformations were significantly higher anteriorly (p< 0.05), and were equivalent to a wedging angle of 0.01–0.3°.

Conclusion: Creep can cause anterior wedge deformity of the vertebral body. In the long term, accumulating creep could cause more severe (and painful?) deformity.

Introduction: There has been an increasing use of orthotic knee braces in the management of knee injuries. To ensure the biomechanics of the knee are not adversely affected, it is important that orthotic knee braces accurately provide the desired angle of immobilisation. The objective of our study was to measure the actual knee flexion angles for a lockable orthotic knee brace, and measure the resulting knee flexion moment.

Materials and methods: Eight healthy male volunteers participated in the study looking at six different types of knee immobilisation: locked in 0, 10, 20, 30 degrees of knee flexion, with the brace unlocked, and without a brace. Force and 3-dimensional motion data were collected using a single Kistler force plate and an eight-camera Qualisys ProReflex motion analysis system.

Results: The kinematic knee flexion angles were significantly different when compared with the angles set at the orthotic knee brace for 0 degrees (p=0.001) and 10 degrees (p=0.011). The kinematic knee flexion angle when no brace was used was significantly different from the angle for the unlocked orthotic knee brace (p= 0.003). The knee flexion moment was directly proportional to the knee flexion angle. There was a statistically significant difference between the knee flexion moment for the six types of immobilisation (p< 0.001).

Discussion: The knee flexion angles measured using the kinematic data did not always correspond with the angle set at the orthotic knee brace. These findings highlight inadequacies in the design of lockable orthotic knee braces, especially at low flexion angles of 0 and 10 degrees. The resulting higher actual knee flexion angles were associated with greater knee flexion moments and joint reaction forces at the tibiofemoral and patellofemoral joints. This can, at best result in increased energy expenditure and decreased agility, and at worse potentially augment injuries to the knee.

Background: Thoraco-lumbar fractures without a neurological deficit are usually suitable for non-operative treatment. The main area of clinical interest is the deformity at the injured levels. The deformity may be evident at the time of presentation, though could be expected to progress in time.

Objective: Accurate assessment of the temporal behaviour in the geometry of the injured segments in non-operatively treated thoracolumbar fractures with normal neurology.

Materials: 102 patients with thoracolumbar fractures without a neurological deficit were treated non-operatively at our unit between June 2003 and May 2006. The mean age of our patient cohort was 46.9 yrs (16–90 yrs). Strict criteria were followed to determine suitability for non-operative treatment. Supine radiographs were performed at the initial assessment. Erect radiographs were performed when trunk control was achieved and at follow-up assessments thereafter.

Methods: Quality Motion Analysis (QMA) software (Medical Metrics Inc, Houston, Tx) was used to measure rotational and translation changes between the end plates using a validated protocol. The radiographs were standardised for magnification and superimposed from different time points. Transformation matrices were used to track the changes. The AO classification was used to classify the fractures by 2 independent observers.

Results: A median of 4 radiographs were analysed for each patient (range 2–9), at a mean follow-up of 5.6 mo (95% CI 4.1–7.1 mo). 92% of the cohort had sustained a 1 level injury. 76% of the injuries were between T12 and L2; 19% were in the thoracic spine. An inter-observer rating of 0.58 was obtained for the classification of the primary fracture type. The mean rotational change was −1.4855° ± 0.248° (95% CI: −0.994° to–1.976°). The mean anterior vertebral body height collapse was −4.3444° ± 0.6938 (95% CI: −2.695 to −5.724). The mean posterior vertebral height collapse was −0.7987 ± 0.259 (95% CI: −0.284 to −1.313).

Conclusions: We report the use of QMA software to track changes in the vertebral body geometry accurately. This has implications on the clinical aspects of management of thoracolumbar fractures based to progression of deformity that could be explored in future studies.

Background data: Previous studies have questioned the quality of information available on the internet. Internet research has proven to more prevalent among scoliosis patients as compared to other orthopaedic conditions.

Aim: Scoliosis websites identified by commonly used search engines were assessed for quality and medical accuracy.

Methods: The word scoliosis was entered into top six search engines and Websites ranked according to frequency. Five websites from the worldwide web and five from the UK only search were evaluated by medical professionals – 4 spinal consultants, 2 registrars, 3 nurses and 1 physiotherapist. 10 patients/carers who had scoliosis surgery also assessed these sites. A scale of 1 to 5 was used for ease of understanding, reliability, clinical correlation, adequacy and links and average score calculated.

Results: None of the top five UK websites figured in the top 5 WWW searchs. Scoliosis research society (SRS) and American Academy of Orthopaedic Surgeons (AAOS) website scored the highest by clinicians and patients in the www list. From the UK list, SAUK website scored the highest with both groups followed by Great Ormond Street Hospital (GOSH) website. We compared the assessment of websites by a healthcare professionals and by patients who had undergone treatment and showed no statistical difference in the scoring.

Conclusion: As treating clinicians it is necessary to educate patients by guiding them to reliable internet sites like SAUK and SRS.

Objective: Prolonged waiting time after being referred for a specialist opinion has plagued the NHS despite pressures to deliver optimum healthcare. We have assessed changes in clinical situation in patients referred to a spinal service while awaiting the first assessment.

Materials & Results: 89 patients were referred to our unit between Jan 2001 and December 2004. The gender distribution in this cohort was equal and the mean age was 50.7 yrs. The mean delay for being seen in the clinic was 28.4 mo (16–58 mo). Significant changes in the symptom pattern were noted in 46 patients, of which 8 patients reported radicular symptoms on a different side. In addition, 7 patients experienced an increased severity in the existing symptoms. 43 patients had been referred to us with an MRI. However due to the delay, 20 of these patients required re-scanning. Following the clinical assessment 25 patients were referred for Physiotherapy, 4 patients required a further clinical review and 44 patients were referred for further imaging.

Conclusion: The problem of excessive out-patient waiting time results in changes in symptom patterns and an increase in the severity of existing symptoms. The changes frequently results in an increased requirement of re-imaging.

Background data: The Paediatric Isola system uses the philosophy of torsion-countertorsion force as a means of scoliosis correction. It aims to maintain this correction till such time that definitive fusion can be carried out.

Aim: This is a retrospective case series of our experience with the Paediatric Isola system and we evaluated the results of this system in the treatment of Scoliosis of various etiologies.

Methods: Twenty –one children,5 with neuromuscular,1 with Ehler-Danlos,5 with idiopathic,3 syndromic and 7 congenital treated with the Isola Instrumentation were studied.

Average age was 6.5 years(2–12). Average follow-up was 24 months (6m-36m).

Results: The average Cobb angle was 52° before surgery, 33.7° after surgery (64 % correction) and 32.5° (62.5% correction) at latest follow-up. The mean apical vertebral translation was 86% and 84% at post-op and latest follow-up. Stabilisation was most commonly perfomed from T2 to L4/L5. Three patients had implant complications, two had deep seated wound infections which necesssiated removal of implants in one case. Five of these patients have gone on to definitive fusions. Curve correction was best for primary thoracolumbar curves and lumbar curves. 2 patients with thoracic curves did not maintain correction.

Conclusion: The Paediatric Isola system is a safe and effective instrumentation in early management of a difficult and challenging sub group of scoliosis patients.

We studied the long term outcome, using the Oswestry Disability Index (ODI), on patients who were managed at our institution between February, 1997, and August, 2004, with a diagnosis of a primary spinal infection, excluding TB or post-operative infection. Patients were identified from databases held within the Departments of Radiology, Orthopaedic Surgery, Neurosurgery and Microbiology. This identified 98 adult patients who fulfilled our inclusion criteria, of who ODIs were calculated on 66, with a mean follow-up of 5 years. There were initially 53 male and 45 female patients with a mean age of 60 years (range 21 0 86) at presentation and symptoms had been present on average for 72 days prior to admission. Back pain was the predominant symptom in 59 and neuropathy in 43. Our figures would suggest a mush higher incidence of primary spinal infection than previously quoted. 75% had significant co-morbidities and 85% of patients under 40 years of age were IV drug users. The causative organisms and their effect were noted. Admission WCC (mean 11.5 ± 8.6) and CRP (mean 128 ± 48) were obtained in the majority of patients (97/98 & 94/98). For those patients who were still available to f/u, the mean ODI was 32 ± 25.

Purpose of Study: To determine whether pre operative psychological assessment can be used to predict the outcome following intradiscal electro thermal therapy (IDET).

Materials and Methods: Patients undergoing IDET at our unit were asked to complete a pain diagram and a Short Form 36 (SF36) (UK Version 1). Patients were followed up after IDET by means of a postal questionnaire. Patients outcome was assessed using a visual analogue pain score (VAS), an SF36 and a subjective outcome assessment. Pain drawings were classified as organic and non-organic according to the principle described by Mann et al.

Results: Forty-six (80.7%) patients were successfully followed up. Mean age was 41.2 years (range 16–76), 27 were female and 19 male. 73.9% of the pain diagrams were classified as organic and 26.1% as non-organic. The pain diagram was a good predictive tool for outcome following IDET. Patients with ‘organic’ pain drawings showed an improvement in mean pain VAS (pre 6.7, post 5.9), high patient satisfaction (Better 67.6%, Same 11.8%, Worse 20.6%), and higher physical component scores of the SF36 (Physical 64.1, Physical Role 45.6, Pain 54.0) compared to the ‘non-organic’ group who demonstrated a deterioration in mean pain VAS (pre 6.5, post 8.2), low patient satisfaction (Better 8.3%, Same 58.3%, Worse 33.3%), and lower physical component scores of the SF36 (Physical 38.3, Physical Role 20.8, Pain 26.5).

Conclusions: Several authors have shown that certain preoperative psychological characteristics are associated with a poor outcome from spinal surgery. Our findings suggest that pre procedure psychological assessment is useful in predicting which patients will have a favourable outcome from IDET. Pain drawings are quick and easy for patients to complete.

It might be a useful predictor in most of the spine surgery. We have incorporated pain diagrams in the questionnaires of patients undergoing anterior spinal surgery and dynamic stabilisation of spine.

Introduction: etiology of late infection after arthroplasty can be difficult to establish. Histology is the gold standard for infection in patients without inflammatory arthritis but diagnosis in inflammatory arthritis depends on culture (Atkins et al). Real-time PCR offers a rapid and direct assessment for staphylococci and enterococci infection but has not been widely assessed.

The aims of this study were

to develop the Roche lightcycler Staphylococcal and Enterococcal PCR kits to facilitate diagnosis of hip and knee prosthetic infections

Methods: uplicate, multiple tissue samples were taken (with separate sterile instruments) at the 1^st stage of revision after informed consent. One set were cultured and results interpreted by the Oxford criteria. The second set were extracted using the Qiagen DNA kit, purified (in-house method) and tested using the Roche lightcycler kits.

Results:53 patients undergoing 2 stage revision for suspected infection were recruited.15 (28.3%) had negative histology and no inflammatory arthritis; 3 with single positive cultures and negative PCR – considered contaminants.

29 patients had non-inflammatory arthritis. 14/18 (77.8%) with positive cultures had staphylococci +/or enterococci isolated and 10 PCR results correlated. The other 11 patients had negative cultures.

9 patients had inflammatory arthritis. Six were culture negative and of the other three, 2 were positive for staphylococci on culture with 1 positive by PCR.

Discussion: Negative staphylococcal PCR correlates with the isolation of staphylococci from only one sample. This agrees with the Oxford criteria that such samples may be considered contaminants. Additional positives detected by staphylococcal PCR alone are rare.

Enterococcal PCR confirmed culture positivity in 2/3 patients. An additional 5 positive PCR’s were obtained from patients’ culture negative for enterococci. It is not clear if these are false positives or more sensitive detection of enterococcal isolation.

Background: Most reports of sickness absence come either from company records, which are limited to specific workforces, or rely on self-report. Electronic recording of sickness certification in primary care medical records provides an alternative source of information.

Purpose: To investigate the validity of electronic sickness certification records in primary care.

Methods: Analysis included 292 primary care LBP consulters, who returned a questionnaire including self-reported work absence, and consented to medical record review. Sickness certification records for 2001–2 were downloaded. Self-reported sickness absence for the previous 2-weeks was matched with electronic records for the same time period. Records were considered to match if there was no reported absence and no certificate, if there was reported absence > =7 days and a certificate, or if reported absence was < 7 days and no certificate was issued.

Results: Overall, 84% of records matched; 87% of employed consulters and 90% of unemployed consulters. Among the employed, 100% of reports of no absence did not have a certificate, 49% of reported absences > =7 days were matched by a certificate for the same time period and lastly, 80% of reported absences of < 7 days did not have a certificate.

Conclusion: We have demonstrated that people with none or short self-reported work absences do not have sickness certificates in their records, but only a small proportion of people with longer self-reported absences appear to have certificates. Further work will investigate possible reasons for non-matching, these may include non-requirement of a certificate, recall errors or incomplete recording of sickness certificates.

Aim: To determine the outcome and need for subsequent surgery in patients following successful closed reduction of dislocation after primary total hip arthroplasty (THA) and the financial implications of re-operation.

Methods: Data was retrospectively obtained from radiographs and patient case notes for all dislocated primary hip replacements presenting to the University Hospital of Wales from January 2000 till November 2005. Records were analysed with a minimum of 1 year follow-up to determine the outcome and need for subsequent surgery following successful closed reduction of dislocation after primary THA. Factors studied include age at primary surgery, indications, components, approach, head size, duration since surgery and direction of dislocation

Results: Over the 6 year study period, 98 patients presented with 100 first time dislocated primary total hip replacements. All the dislocations underwent successful closed reduction. 62 (62%) hips re-dislocated more that once. At minimum follow up of 1 year, 7 patients had died and were excluded from the final study group. Of the remaining 93 hips, 46 patients have had no further surgery. 44 THA’s have undergone revision procedures and 3 are waiting to have revision surgery (51% in total). Of those who have undergone revision surgery, 7 hips re-dislocated since and 3 of those needed further re-revision.

Discussion: Dislocation following primary THA remains a problem with varying dislocation rates quoted in the literature. In our series, 51% of patients presenting with dislocation required revision surgery. All patients in this series had 28 mm or smaller femoral heads. The financial impact of the burden of revision surgery continues to increase. In this series in isolation the cost of revision surgery totalled greater that £500,000.

Introduction: Complex tibial diaphyseal fractures are rare injuries and can present significant challenges to the surgeon. Successful fixation and subsequent union can be difficult to achieve due to the relatively poor blood supply of the tibia and extent of soft tissue injury. This study describes our early experience of treating eighteen patients with these injuries by the Ilizarov method.

Methods: Patients were prospectively identified. Follow up was performed in the out-patient clinic and by notes review. Fractures were classified using the AO classification. Bony union was evaluated on both a clinical and radiological basis, which included remodelling bone trabeculae on two radiographs and ability to weight bear without discomfort or walking aids on a dynamised frame. The mean patient age was 38 years with a male: female ratio of 12:6. Of the eighteen patients four had concomitant injuries.

Results: There were four 42-B3 type fractures, seven 42-C1 and seven 42-C3. Ten were open (eight IIIB, two IIIA) and eight closed. We identified two groups: closed fractures and open fractures. The mean time to union in the closed group was 149 days (21 weeks) and 186 days (27 weeks) in the open group. There was one hypertrophic non union requiring further surgery using the Ilizarov method. Six patients had an episode of superficial pin site infection, all of which settled with oral antibiotic therapy. There was no deep sepsis. No patients required bone grafting.

Conclusion: The Ilizarov method offers safe, reliable and rapid healing for both closed and open complex tibial diaphyseal fractures. These early results demonstrate improvements in union times and complication rates when compared with similar injuries treated by internal fixation.

Introduction: Restoration of vertebral height for burst fractures can be achieved either anteriorly, posteriorly or combined.

Aim: To biomechanically assess and compare stiffness of 1) posterior pedicle screws with Synex, 2) Synex+ Double screw+rod Ventrofix 3) Synex+ Double screw+ Single rod and 4) Synex+ Single screw+ Single rod in reconstructing an unstable burst fracture following anterior corpectomy.

Method: Fresh frozen calf lumbar spines (L3–L5) were dissected and L4 corpectomy performed. L3 and L5 were mounted on a plate and fixed. Loads were applied as a dead weight of 2Nm. The range of movement was measured using the Qualisys motion analysis system using external marker clusters attached to L3 and L5. Bony landmarks were identified with marker clusters as baseline. The movement was measured between the 2 marker clusters.

Five specimens were implanted for each group 1) with pedicle screw (into L3 and L5) and tested with/without Synex (expandable) cage anteriorly, 2) implanted with a Synex cage and Double screw+rod Ventrofix system, 3) Synex cage and Double screw+ Single rod Ventrofix construct and 4) Synex cage and Single screw+ Single rod Ventrofix system.

Results: Reconstruction of the anterior column with the combination of Synex and double rod Ventrofix produces a stiffer construct than the pedicle screw system in all planes of movement (p= 0.001 in rotation).

The double screw/ single rod system is less effective than the Ventrofix System but is comparable to the pedicle screw construct.

The single screw/ single rod construct leads to unacceptable movement about the axis of the inferior screw particularly in extension with a ROM much greater than the intact spine (p< 0.001)

Conclusion: Thus biomechanically we recommend Synex and double rod Ventrofix construct to reconstruct the anterior vertebral column following corpectomy for unstable burst fractures.

Aim: To determine the incidence of adjacent level osteophytes in patients who have had anterior cervical fusion using an anterior cervical plate as compared to those who are fused without an anterior cervical plate.

Design: We retrospectively reviewed the lateral radiograms of sixty two patients who have had an anterior cervical fusion with a minimum follow up of twelve months.

Materials and methods: We looked for the development of adjacent level osteophytes in these patients at their final follow up, which was generally at the time radiological fusion. There were 27 patients in the first group who had an anterior cervical plate used to fix the vertebrae in addition to the Cervios cage, while the 35 patients in the second group in whom only a Rabea cage was used for the fusion. The mean follow-up was 20.6 months (range 12–48).

Results: 64.3% of the patients who had an anterior cervical plate developed adjacent level osteophytes while none of the patients who have had the fusion without the cage developed the osteophytes.

Conclusion: We found the patients who had an anterior cervical interbody fusion using a plate had a significant risk of developing adjacent level osteophytes while this is not seen in patients who do not have the plate for the fixation.

Background: Spinal infections are rare, the reported incidence in the UK is between 1:50,000 and 1 in 250,000. Functional outcome following spinal infection is not widely reported in the literature

Methods: Over a 7-year period, all adult patients presenting to a tertiary referral centre with a diagnosis of primary pyogenic spinal infection (epidural abscess, osteomyleitis or spondylodiscitis) were identified. Data at presentation was collected and included: C-reactive Protein (CRP), white cell count (WCC), time interval between onset of symptoms and presentation to tertiary referral centre causative organism, level of spinal infection and surgery. Functional outcome was assessed using a validated tool – The Oswestry Disability Index (ODI)

Results: 96 patients were identified, mean age 61 years (22–87), 51 (53%) male. ODI was available for 78% of live patients; the mean follow-up period being 5.5 years (21–120 months). The median ODI was 42 (0–84). An elevated CRP was significantly associated with a poorer functional outcome (p=0.05). Surgical intervention was related to improved functional outcome but did not reach statistical significance. WCC and the presence of an abscess were not related to functional outcome.

Conclusion: In out study we have found that the higher the CRP at presentation the poorer the functional outcome.

Purpose of Study: To prospectively study the clinical and radiological outcomes following lumbar interbody fusion with an intersegmental device(SpineLink™, Biomet) in smokers versus non smokers.

Materials and Methods: 64 patients who underwent spine fusion with intrasegmental fixation were prospectively studied at Mayday University Hospital. 54 patients with suffient follow up were included. Patients were assessed pre and postoperatively clinically using validated scoring systems (VAS pain score, SF-36 v1, Oswestry Disability Index). Radiologically classified into fused, indeterminate or pseudoarthrosis.

Results: There were 54 patients in the analysis (34 patients in the smoker group and 20 patients in the non smoking group) with an average age of 52 years and an average follow-up of 28 months. 32 patients had multilevel procedures (25 two level, 5 three level, 2 four level). The treatment groups were comparable with respect to demographic, diagnostic (53% spondylolisthesis, 35% degenerative disc disease, 12% other) and surgical variables. No other significant medical problems affected patients in either group. Radiographically there were no pseudarthroses observed in either group. The SF-36 physical health score increased from 22.4 to 40.1 (+18.0) following surgery in smokers compared to an increase from 25.0 to 36.0 (+11.0) in non-smokers. The SF-36 mental health score increased from 36.4 to 45.0 (+8.6) in smokers compared to an increase of 30.8 to 42.7 (+2.9) in non-smokers. Complications included 2 nerve root injuries requiring hardware removal, and 3 deep infections which resolved with appropriate treatment.

Conclusions: There were no differences between smokers and non-smokers in radiographic fusion success or postoperative complications. As expected, smokers had lower SF-36 physical health and mental health scores pre-op, but unexpectedly, smokers had a greater degree of improvement in these scores postoperatively than non-smokers. Thus, from our experience, there is an incremental benefit to the use of intrasegmental fixation in smokers and warrants further investigation.

Objective: To investigate the clinical outcomes, and the requirement of surgery following selective nerve root block performed for cervical radicular pain in patients with MRI proven disc pathology.

Methods: Thirty consecutive patients with cervical radiculopathy and correlating MRI pathology were studied. Mean age of patient was 46yrs (range 28–64yrs). Twenty nine of the thirty patients also complained of associated neck pain. All underwent fluoroscopically guided, selective cervical nerve root block with steroid (20mg Depomedrone) and local anaesthetic (0.5ml Bupivo-caine 0.25%). Radiographic contrast was used to confirm needle position. All procedures were conducted by the same clinician.

Pre and post procedure pain and physical function scores were noted using the standard SF 36 questionnaire, as well as whether subsequent surgery was required. Mean follow up time was seven months (range 2–13 months).

Results: 81% of patients reported an improvement in arm pain, and 66% in neck pain following the procedure. 77% of patients had an improvement in pain score (mean improvement 16 points). 68% of patients had an improvement in physical function score (mean improvement 20 points). At the time of follow up only one patient had undergone surgery for cervical radicular pain.

Conclusion: This study suggests that fluoroscopically guided selective nerve root block is a clinically effective interventional procedure in the management of cervical radicular pain, and may prevent the need for open surgery.

Aim: To investigate the outcome following revision total hip arthroplasty (THA) using 36 mm and 40 mm modular femoral heads.

Methods: Details were retrieved from our arthroplasty database regarding all revision THAs done in our unit using 36 mm and 40 mm femoral heads. Follow-up information was obtained from patient records and telephone conversation.

Results: The cohort considered totalled 107 revision THAs, 93 using a 36 mm head and 14 using a 40 mm head. All received either highly cross-linked UHMWPE liners or metal on metal liners. The indications for revisions were recurrent instability in eight, periprosthetic fracture in 11, second stage revision in 24, fracture of the femoral stem in one and aseptic loosening in the remaining 63. At a minimum follow up of one year, information was not available for five but they did not have any record of dislocation. Out of the remaining 102 patients, dislocation occurred in 4 hips (3.9%). None of the revisions done with 40 mm head dislocated. In two of the dislocations, the initial indication for revision THA was recurrent instability and if they are excluded, the dislocation rate was 1.96%.

Discussion: Dislocation and the sequalae of recurrent instability remains a significant problem following revision THA and the existing literature varies greatly in the quoted dislocation rates. We believe that the use of 36 mm and 40 mm femoral heads in our unit has been a major factor in low (3.6%) dislocation rate following revision THA. To date there have been no problems encountered resulting from the use of highly cross-linked UHMWPE.

Physical activity is a key determinant of bone mass and health, however during adulthood and ageing there appears to be a decrease in the ability to respond positively to exercise which is variable between individuals. While exercise is known to protect against the osteopo-rotic process with modest increases in BMD the exact cellular and molecular responses are poorly understood.

We have studied the effect of mechanical stimulation on bone histomorphometric parameters, osteocyte viability and gene expression in human trabecular bone maintained in a 3D bioreactor.

Trabecular bone cores were prepared from femoral head tissue removed from patients undergoing total hip arthroplasty and maintained in the bioreactor system for 3 (n= 4 patients), 7 (n=5 patients) or 28 days (n=1 patient). Cores (n=3 per patient) were either frozen directly on preparation (T0), placed in the bioreactor system and subjected to Mechanical stimulation (3000 μstrain in jumping exercise waveform repeated at 1Hz for 5 minutes daily) or maintained in the bioreactor system with no mechanical stimulation as control. After the experimental period total cell numbers, cell viability and apoptosis were determined in un-decalcified cryosections at specific distances throughout the bone cores by nuclear staining (DAPI), lactate dehydrogenase activity (LDH) and Nick Translation Assay respectively. Consecutive sections were collected and RNA extracted for gene expression analysis.

Mechanical stimulation was shown to increase Bone Formation Rate (BFR) as determined by Calcein label/ distance to bone surface in the 28 day experiment (BFR mcm/day Control 0.01 ± 0.0035 vs Load 0.055 ± 0.0036 p=0.0022). Expression of bone formation markers such as Alkaline Phosphatase and Collagen Type I was shown to increase in all patients however there was an individual variation in the response of Osteopontin to mechanical stimulation as determined by quantitative real time PCR expression analysis. Numbers of viable osteocytes at T0 varied between individual patients however viability was significantly increased and apoptosis decreased in association with mechanical stimulation compared to control in all patient samples examined (p to 0.021). Our data tend to support animal model findings relating to the osteocyte saving effects of exercise and provide an insight into the molecular detail of the exercise response in human bone.

Introduction: We present here the clinical features and management strategies of patients with gluteus medius and minimus enthesopathy.

Methodology: We studied seven patients with lateral hip pain and tenderness on palpation, worse over the tip of the greater trochanter. All of them had a positive Trendelenburg’s sign, and a transient relief of pain on injecting local anaesthetic in the abductor mechanism. All of these patients were tertiary referrals from the rheumatologists, who had at least once injected them with corticosteroids.

Results: Four of these seven patients underwent exploration. An insertional tendinopathy of the abductors was noted in all the patients, and was debrided. Two of the patients had, in addition, a tear in the gluteus medius tendon, which was repaired. One patient had an injection of local anaesthetic and Aprotinin in the abductor mechanism with resolution of symptoms.

Discussion: Gluteus medius and minimus enthesopathy is a distinct clinical entity. Although the condition has been described in the radiological literature, we were unable to find any reference to the orthopaedic management of this condition. We observed only a small number of patients, and we are thus unable to provide definite answers. Patients presenting with the above clinical features warrant consideration of the diagnosis of abductor enthesopathy. Ultrasound scan or MRI scan helps in confirming the diagnosis. At present, our management protocol involves injecting a local anaesthetic / Aprotinin in the abductor mechanism. However, we are cautious in injecting more than once, as, at operation, we have observed necrosis of the abductor mechanism at its insertion in two patients, similar to that described for Achilles tendon. If this fails, we undetake surgical exploration. The exact surgical procedure is difficult to predict and may involve debridement and repair of the pathological tendon.

Introduction: In this study the optimal angle of fixation or splintage for partially weight bearing fractures of the patella was determined by a gait analysis measurement system.

Subjects and Methods: A knee brace was applied to eight subjects and locked at 0, 10, 20 and 30 degrees. Measurements were also taken for an unlocked brace and in the absence of a brace. The subjects were instructed on partial weight bearing mobilisation. Three dimensional motion analyses were performed using an infrared 8-camera system. The ground reaction force was recorded by two 3-dimensional force plates embedded in the walkway. Kinematic and kinetic data was collected and the data was transferred to a computer programme for further analysis and the forces acting on the patella were calculated.

Results: The results showed that the forces acting on the patella were directly proportional to the knee flexion angle. The results also showed that the knee flexion angle does not always correspond with the angle set at the knee brace; however they did exhibit a direct relationship.

Conclusion: Our findings show that, for partially weight bearing patella fractures, the optimum form of splintage corresponds with a low knee flexion angle.

A combination of stem cell therapy and tissue engineering is emerging as one of the most promising approaches for skeletal tissue repair and regeneration. Osteoinduction of human bone marrow mesenchymal stem cells (MSCs) is initiated through local signals or growth factors, of which the bone morphogenetic proteins (BMPs) are the best characterised. Cytomodulin-1 (CM-1), a synthetic heptapeptide with functional similarity to members of the TGF-B super family, has been classified as a novel growth factor associated with osteoinduction of MSCs. However, the effects of CM-1 on human bone MSCs are still unclear. The aim of this study was to determine any effects for CM-1 and its scrambled control (CM-1 SCRAM) on the proliferation and differentiation of human bone marrow MSCs along the osteogenic lineage.

Primary human bone marrow MSCs were cultured in the presence of CM-1 and CM-1 SCRAM at a range of concentrations (10-8M – 10-6M) in vitro for up to three weeks. 100 ng/mL of recombinant human BMP-2 (rhBMP-2) was used as a positive control. At the end of the culture period, histological and biochemical assays were carried out on the cultures.

Biochemical assays revealed that 10-7M of CM-1 significantly stimulated alkaline phosphatase specific activity compared with the negative control group (P< 0.05) in a similar way to the rhBMP-2 positive control group. These data were supported by an observed increase in positive alkaline phosphatase staining in the 10-7M of CM-1 and rhBMP-2 treated cells. However, total DNA content was not significantly different between any of the groups.

This study indicated the potential of using CM-1 as an osteogenic growth factor for skeletal tissue regeneration which may provide an alternative approach to meet the major clinical need in orthopaedics and craniofacial surgery.

* Cytomodulin-1 and the scrambled control were genuine gifts from Professor (emeritus) Rajendra S. Bhatnagar at the Department of Bioengineering, University California Berkley, USA.

Purpose of study: We report the results of a prospective case series of 10 patients who developed tumour-like masses following resurfacing arthroplasty

Method: Ten subjects were referred to the tumour service at the Nuffield Orthopaedic Centre with symptomatic masses around the hip, all had previously received a resurfacing arthroplasty.

We report the clinical, radiographic and histologic features of these cases.

Results: MRI and ultrasound scanning was preformed, which demonstrated masses with solid and cystic components.

Biopsy was performed and subsequent histological examination revealed a profound plasma-cell lymphocytic response associated with metal wear debris.

There were no infections in this series.

Three subjects required revision surgery.

Conclusion: Over 50,000 resurfacing arthroplasties have been implanted worldwide over the past ten years. Although the early clinical results are encouraging little is known about the long term consequences of large head metal on metal bearing surfaces. Despite this, these devices are being widely marketed and are often implanted in younger patients. Resurfacing arthroplasties are associated with high serum and urine metal ion concentrations, metal particles have also been shown to migrate along the lymphatic system. In addition, there is now evidence that high local metal ion concentrations can induce haempoietic cancers.

This study suggests that resurfacing arthoplasty can also induce a local hypersensitivity reaction in response to metal wear debris. It therefore raises new concerns regarding the long-term safety of this procedure.

Background: Each year, 7% of the adult population consult their General Practitioner (GP) with low back pain (LBP). Approximately half of these patients still experience disabling pain after three months. Evidence suggests a biopsychosocial approach may be effective at reducing long-term pain and disability. This study aimed to evaluate, for persistent disabling LBP, the effectiveness of an exercise, education and cognitive behavioural therapy intervention compared to usual GP care plus educational material, and to investigate the effect of patient preference.

Method: Design: randomised controlled trial. Patients, aged 18–65yrs, consulting their GP with LBP were recruited. After 3 months those still reporting disabling LBP (≥20mm on 100mm pain visual analogue scale (VAS) and ≥5 Roland and Morris Disability Questionnaire (RMDQ) points) were randomised, having first established preference, to 2 groups. VAS and RMDQ were assessed at 0, 6, and 12-months post-intervention.

Results: 234 patients were randomised; 116 to the intervention. The intervention showed small non-significant effects at reducing pain (3.6mm) and disability (0.6points RMDQ) over one year. Preference showed significant interaction with treatment effect at one-year; patients had better outcomes if they received their preferred treatment.

Conclusion: The above intervention program produces only a modest effect in reducing LBP and disability over a one-year period. These results add to accumulating evidence that interventions for LBP produce, at best, only moderate benefits. The challenge for future research is to evaluate interventions tailored for specific LBP sub-populations. These results suggest that if patients receive treatment which they believe is beneficial their outcome can be optimised.

Introduction: Elective Orthopaedics has been targeted by the department of health in the U.K. as a maximum six-month waiting time for operations could not be met. National Orthopaedic project was initiated as a consequence and Independent Sector Treatment Centres (ISTC) and well established private hospitals were utilised to treat NHS long wait patients.

Materials and Methods: We audited the primary total hip replacements performed in our hospital in 1998 and 2003 to compare the differences in the patient characteristics in particular age, length of stay and ASA grade.

Results: The number of hip replacements increased to 308 in year 2003 from 194 in year 1998. Whilst, the number of ASA I patients were the same, the ASA II. III, IV increased by 40%, 260%, 266% respectively. The average length of stay decreased from 14.3 to 11.9 days which was statistically significant, in spite of increased numbers of ASA II – IV patients.

Discussion: The NHS hospitals are treating increasing number of patients who have a higher anaesthetic risk and are likely to stay longer in the hospital in the post-operative period. The case mix for primary total hip replacements in large tertiary referral hospitals have changed due to altered patient flow due to cherry picking of NHS waiting lists by the ISTC. NHS hospitals should be appropriately remunerated for dealing with complex cases and for managing complications referred by ISTC hospitals. In fact, the National joint registry’s 2^nd annual report confirms that 40% of primary total hip replacements operated in ISTC’s were ASA I while only 25% of primary total hip replacements operated in NHS hospitals were ASA I. None of the ISTC’s performed complex primary THRs.

Patella and extensor mechanism injuries are common injuries and are generally managed with some degree of immobilisation and partial weight bearing to facilitate healing. The aim of this project was to determine the type of immobilisation or splintage during partial weight bearing that results in minimal forces acting through the extensor mechanism.

Gait analysis studies were performed on eight healthy male subjects mobilising partially weight bearing. Measurements were taken for six types of immobilisation: locked at 0, 10, 20, 30 degrees and unlocked in an orthotic knee brace, and without a brace. The ground reaction force, knee joint angle and the knee flexion moment were measured using Qualisys Track Manager and Visual 3D Software. The extensor mechanism moment and the extensor mechanism force were calculated using static equilibrium equations and documented data. A one-way analysis of variance statistical test was performed to determine the statistical significance of the differences between the six types of immobilisation.

There was a direct relationship between the knee flex-ion angle and the extensor mechanism force. The extensor mechanism force at 0 degrees of immobilisation was significantly lower than that for 20 and 30 degrees (p< 0.05). The increase in the extensor mechanism moment arm with increasing knee flexion was not suf-ficient to offset the increase in the extensor mechanism force caused by the increase in the knee flexion moment. The results also showed that the knee flexion angle does not always correspond with the angle set at the knee brace; however they did exhibit a direct relationship.

These results have important implications for the management of patients with patella and extensor mechanism injuries. The results suggest that improvements in knee brace design to allow 0 degrees of knee flexion, rather than the 10 degrees as seen in this study, are likely to result in significantly reduced extensor mechanism tensile forces.

Purpose: The aims of our study were: (i) to measure the total metal content in cell saver blood recovered during revision hip arthroplasty, (ii) to evaluate the efficacy of centrifuging and washing the recovered blood in reducing the metal content, (iii) to investigate whether transfusion of the salvaged blood resulted in a significant increase in the metal ion levels in the patients’ blood in the immediate post-operative period.

Materials and methods: We analysed the levels of metallic debris and metal ions in cell saver blood in nine patients undergoing revision hip replacement. Using inductively coupled plasma mass spectrometry (ICP-MS), the levels were measured for titanium, aluminium, vanadium, chromium, cobalt, nickel and molybdenum. The metal ion levels were analysed using a dilution technique and the total metal content levels (particulate debris and ions) were analysed with a digestion technique.

Results: Significantly higher levels of metal ions and metal debris were found in the pre-processed blood compared with the processed blood (after centrifuging and washing). The ion levels in the processed blood were not high enough to cause a significant increase in the patients’ immediate post-operative blood ion levels when compared with pre-operative levels.

Conclusion: There are markedly elevated levels of metal ions and particulate metal debris in the blood salvaged during revision total hip arthroplasty. The processing of the recovered blood in a commercial ‘cell saver’ sig-nificantly reduces the total metal load that is re-infused. Re-infusion of salvaged blood does not result in elevated metal ion levels in the immediate post-operative period.

Background: Many studies have examined magnetic resonance images (MRI) with a view to the anatomy and signaling properties of the intervertebral disc and adjacent tissues in asymptomatic populations. In this study we have examined MRIs of a discrete population of patients undergoing surgery for symptomatic disc herniations.

Methods: Sixty patients (aged 23–66 years, mean 41.5±8.4) had sagittal T1 and T2- weighted turbo spin echo imaging of the lumbar spine prior to surgery. One disc was herniated at L2-3, 3 at L3-4, 22 at L4-5 and 31 at L5-S1; 3 patients had herniations at both L4-5 and L5-S1. The images were scored for disc narrowing and signal, degree of anterior and posterior bulging and herniation, and assessed for Modic I and II endplate changes and fatty degeneration within the vertebrae. These were carried out for each of 6 discs (T12-S1) for all patients (ie 360 discs and 720 endplates).

Results: There were trends of increasing disc narrowing, disc bulging and fatty degeneration with increasing age in these patients. 83% of patients had disc bulging, 53% had endplate irregularities and 44% had fatty degeneration. There was a significant correlation between patient weight and fatty degeneration. 7.5% of vertebrae (in 22% of patients) demonstrated Modic I changes whilst Modic II changes were seen in 14% of vertebrae (40% of patients). This is considerably higher than the incidence reported in asymptomatic individuals where Modic I changes were seen in 0.7% of vertebrae (3% of individuals) and Modic II changes in 1.9% of vertebrae (10% of individuals).

Conclusion: There is a higher incidence of Modic I and II changes in disc herniation patients than in asymptomatic individuals.

Introduction: Prophylactic pinning of an asymptomatic hip in SCFE is controversial. Bone age has been used as evidence of future contralateral slip risk and used as an indication for such intervention. The efficacy of bone age assessment at predicting contralateral slip was tested in this study.

Patients and Methods: 18 Caucasian children prospectively had bone age assessment using wrist and hand x-rays when presenting with a unilateral SCFE. Patients and parents were informed about the chance of con-tralateral slip and risks of prophylactic fixation, and advised to attend hospital immediately on development of symptoms in contralateral hip. After in-situ fixation of the affected side prospective monitoring in outpatient department was performed. Surgical intervention was undertaken if the contralateral hip was symptomatic.

Results: Three children (2 boys) went on to develop to a contralateral slip at a mean of 20 months from initial presentation. 6 children (5 boys) were deemed at risk of contralateral slip due to a bone age below 12.5 years for boys and 10.5 for girls. Only one from this group developed a contralateral slip. The relative risk of proceeding to contralateral slip when the bone age is below the designated values was 1 (95% confidence interval of 0.1118 to 8.95). The sensitivity and specificity were 33% and 66% respectively. With positive predictive value of 15% and diagnostic efficiency of 61%.

Conclusion: Delayed bone age by itself is not a good predictor of future contralateral slip at initial presentation. Routine prophylactic pinning is not justified based on bone age alone, with the risks of surgical fixation it carries. Prospective long term longitudinal study is required.

Introduction: Templating of radiographs is part of pre-operative planning in Total Hip Replacement (THR). Digital radiograph technology allows the manipulation of images, altering magnification and therefore affecting accuracy and reproducibility in templating. We have performed a study to investigate templating for hybrid total hip arthroplasty comparing digital hard copies with three computer methods to scale for magnification, in order to assess whether on-screen images can be templated directly with existing acetate templates.

Methods: 20 patients undergoing hybrid THR had pre-operative radiographs taken with a 10 pence coin attached to the skin overlying their greater trochanter. On-screen computer images were manipulated using either the 10p coin as a marker to scale for magnification, or two digital line methods using computer software against external ruler scales. Templating were performed for acetabular size, femoral offset, stem offset and stem size by three grades of observer, and the on-screen images were compared with hard copy digital prints. Intraclass Correlation (ICC) analyses were performed to assess intra-observer and inter-observer variability for the four methods. Comparisons were also made between templated results and the sizes of the inserted prostheses.

Results: All methods showed good reproducibility with all ICC values for intra-observer variability greater than 0.7. Inter-observer variability was less consistent, and the two digital line methods were the least reliable, with accuracy of sizing compared with the inserted prostheses varying between −1.6% to +10.2%. The hard copy radiographs showed better reproducibility than the 10p method, but less accuracy with 3.7% under-sizing. The 10p method was most accurate, with no significant differences for offset or acetabulum compared with the inserted prostheses, and templated under-sizing of only 0.9%.

Discussion: On-screen templating of digital radiographs with standard acetate templates is accurate and reproducible if a radio-opaque marker such as a 10p coin is included when taking the original radiograph.

Introduction: Atraumatic vertebral deformity could possibly arise from sustained loading by the adjacent intervertebral discs, especially when discs are degenerated and press unevenly on the vertebra (1). Creep phenomena have been studied in samples of cancellous and cortical bone, but little is known about their potential to deform whole bones. We hypothesise that sustained asymmetrical loading of a vertebral body can cause differential creep, and vertebral deformity.

Materials and methods: Five thoracolumbar ‘motion segments’ (two vertebrae with intervening soft tissues) were dissected from human cadavers aged 64-88 yrs. Each specimen was subjected to a 1.5 kN compressive force for 2 hrs, applied via plaster moulded to its outer surfaces. Specimens were positioned in 2 deg flexion to simulate a stooped posture. Six reflective markers were attached to pins inserted into the lateral cortex of each vertebral body. Anterior, middle and posterior vertebral body heights were measured at 1 Hz to an accuracy of 7 microns, using a MacReflex 2D optical tracking device. This enabled elastic and creep strains in the vertebral cortex to be plotted against time. Compressive ‘stress’ acting vertically on the vertebral body was quantified by pulling a miniature pressure transducer along the mid-sagittal diameter of adjacent discs (1).

Results: Maximum elastic compressive strains in the posterior, middle and anterior cortex were 500-700, 800-2000 and 600-2500 microstrains respectively. Corresponding creep strains were 200-1500, 200-3200 and 500-5500 microstrains. Increased strains in the anterior vertebral body corresponded to increased stresses in the anterior annulus of adjacent discs. Creep was greater in older specimens, and was only partially reversible. ‘Permanent’ anterior wedging of the vertebral body could reach 0.7 deg after 2 hrs.

Discussion: These preliminary results suggest that vertebral deformity in-vivo can arise by creep mechanisms, when total (elastic+creep) strain locally exceeds the yield strain of bone (2). Future experiments will consider the middle vertebra in three-vertebra specimens.

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.

Introduction: Prophylactic pinning of an asymptomatic hip in SCFE is controversial. Bone age has been used as evidence of future contralateral slip risk and used as an indication for such intervention. The efficacy of bone age assessment at predicting contralateral slip was tested in this study.

Patients and Methods: 18 Caucasian children prospectively had bone age assessment using wrist and hand x-rays when presenting with a unilateral SCFE. Patients and parents were informed about the chance of con-tralateral slip and risks of prophylactic fixation, and advised to attend hospital immediately on development of symptoms in contralateral hip. After in-situ fixation of the affected side prospective monitoring in outpatient department was performed. Surgical intervention was undertaken if the contralateral hip was symptomatic.

Results: Three children (2 boys) went on to develop to a contralateral slip at a mean of 20 months from initial presentation. 6 children (5 boys) were deemed at risk of contralateral slip due to a bone age below 12.5 years for boys and 10.5 for girls. Only one from this group developed a contralateral slip. The relative risk of proceeding to contralateral slip when the bone age is below the designated values was 1 (95% confidence interval of 0.1118 to 8.95). The sensitivity and specificity were 33% and 66% respectively. With positive predictive value of 15% and diagnostic efficiency of 61%.

Conclusion: Delayed bone age by itself is not a good predictor of future contralateral slip at initial presentation. Routine prophylactic pinning is not justified based on bone age alone, with the risks of surgical fixation it carries. Prospective long term longitudinal study is required.

Introduction: We report our experience with the ZMR Hip System (Zimmer Inc.). The system accommodates a number of femoral fixation philosophies including spline, porous and taper stem options. The tapered stem is designed to achieve a distal wedge fit and also allow bone on-growth via the corundumized titanium alloy surface. The modular mid-stem junction allows a selection of body designs to be selected providing significant intra-operative flexibility and version adjustment.

Method: This study considers 64 cases performed in 63 patients with a mean age at the time of surgery of 70 years (range 55–89) utilising the taper stem design. The indication for revision surgery was aseptic loosening in 33 patients (Paprosky types II – 12, IIIA-10, IIIB-11) 22 peri-prosthetic fractures (Vancouver types B2-15, B3-7), 8 for infection and 4 patients with instability.

Results: The cohort had a minimum three-year follow-up with a mean of 50 months (range 36–72) and clinical assessment included Oxford score and thigh pain assessment. Engh’s criteria was utilised in the radiological evaluation when considering femoral component fixation. Femoral stem subsidence and femoral bone stock were also appraised on serial follow-up radiographs.

Discussion: The survival rate at follow-up with stem revision being the end point was 100%. When re-operation for any reason and radiological loosing are considered as the end point the survival rate was 95%.

Conclusion: We conclude excellent medium term results with the use of a cementless modular taper stem in challenging femoral revision surgery.

Background: Metal-on-Metal (MoM) hip bearings are being implanted in ever increasing numbers and into ever-younger patients. The consequence of chronic exposure to metal ions is a cause for concern. Therefore, by using cytogenetic biomarkers, we investigated a group of patients who have had MoM bearings in-situ for in excess of 30 years.

Method: Whole blood specimens were obtained from an historical group of patients who have had MoM bearings in-situ for in excess of 30 years. Blood was also obtained from an age and sex matched control group and from patients with Metal-on-Polyethylene (MoP) components of the same era.

The whole blood was cultured with Pb-Max karyotyping medium and harvested for cytogenetics after 72 h. The 24 colour FISH (Fluorescent In Situ Hybridisation) chromosome painting technique was performed on the freshly prepared slides allowing chromosomal mapping. Each slide was evaluated for chromosomal aberrations (deletions, fragments and translocations) against the normal 46 (22 pairs and two sex) chromosomes. At least 20 metaphases per sample were scored and the number of Aberrations per cell calculated.

Results: Chromosomal aberrations, including deletions, fragments and translocations were only detected in the peripheral blood lymphocytes isolated from the group that had MoM bearings. These changes were not present in the age and sex matched control group. The chromosomal aberrations were also detected in the patients previously exposed to MoM bearings who have been revised to a MoP articulation.

Conclusion: We have detected dramatic chromosomal aberrations in peripheral blood lymphocytes in a group of patients chronically exposed (over 30 years) to elevated metal ions. It is not known whether these aberrations have clinical consequences or whether they are reproduced in other cells in the body. The results emphasise the need for further investigations into the effect of chronic exposure to elevated metal ions produced by Orthopaedic implants.

There is concern that intra-articular electrosurgical ablation may cause thermal soft tissue damage, particularly chondrolysis, if excessive temperatures are reached. The aim of this study was to determine whether the intra-articular temperature during arthroscopic subacromial decompression using a monopolar electrosurgical ablator remains below a safe level. Data was collected prospectively from consecutive shoulder arthroscopic subacromial decompressions performed at our institution. Shoulder arthroscopy was performed using three standard portals. Evaluation of the glenohumeral joint and subacromial space was performed in a standard manner. Soft tissue resection of the subacromial bursa was performed using a monopolar electrosurgical ablator probe with continuous integral suction. Additional procedures such as acromioclavicular joint excision and rotator cuff debridement or repair were performed as appropriate. Bone resection, if required was performed using an arthroscopic burr. The temperature of the fluid within the shoulder and subacromial space was continuously monitored using a sterile digital temperature probe. The surgeon performing the procedure was blinded the collection of data. Data from thirty subacromial decompressions has been collected. 8 patients had full thickness cuff tears of which 6 were debrided, and 2 repaired arthroscopically. 13 patients had acromioclavicular joint excision. Mean operating time was 46 minutes (30–107). The infusion pressure ranged from 40 to 65 mmHg. The median volume of infused fluid was 3900 ml (1500 to 9000). The starting temperature ranged from 18.3 to 21.9. The mean maximum temperature reached was 27.6 (range 22.7 to 41.8 °C). The results suggest that the intra-articular temperature is maintained within safe levels when a monopolar electrosurgical ablator with integral suction is used to perform soft tissue subacromial decompression.

When deciding on treatment for displaced mid-shaft clavicle fractures, patients often inquire if repair of (potential) nonunion results in outcome similar to acute fixation. We used objective muscle strength testing and patient-oriented outcome measures to examine this question. Late reconstruction of nonunion following displaced mid-shaft fractures of the clavicle results in restoration of objective muscle strength similar to that seen with immediate fixation. However, there was a significant loss in muscle endurance as well as a trend towards a decrease in outcome scores (DASH, Constant) following late reconstruction. This information is useful in surgical decision making and in counseling patients.

Using objectively measured strength and patient-oriented health-status instruments, we sought to determine if delay in repair of displaced, mid-shaft clavicle fractures negatively affected shoulder strength or outcome.

Late reconstruction of clavicle nonunion results in restoration of objective muscle strength similar to that seen with immediate fracture fixation, but there was a significant loss in muscle endurance as well as a trend towards a decrease in outcome scores (DASH, Constant).

All patients had sustained completely displaced, closed, isolated mid-shaft clavicle fractures. Fifteen patients had immediate plate fixation (mean 0.6 months post-fracture) and fifteen had plate fixation for non-union (mean fifty-eight months post-fracture). Objective muscle strength testing on the BTE was done a mean of twenty-nine months post-fixation (normal contralateral limb as control). There were no significant differences between acute fixation and delayed reconstruction groups with regards to strength of shoulder flexion (acute = 92.4%, delayed = 89.4%, p=0.56), shoulder abduction (acute = 98.8%, delayed = 96.7, p=0.75), external rotation (acute = 98.4%, delayed = 91.9%, p=0.29), or internal rotation (acute = 96.3%, delayed = 97.4%, p=0.87). However, there was a trend for improved Constant scores (acute = 94.5, delayed = 90, p=0.09) and the DASH scores (acute = 3.4, delayed = 9.0, p=0.09) in the acute fixation group. We found a significant decrease in muscle endurance with regards to shoulder flexion (acute = 107.0%, delayed = 71.1%, p=0.007) and a trend towards weaker shoulder abduction (acute = 103.1%, delayed = 88.7 %).

Funding: Mr. Potter was supported by a St. Michael’s Hospital Summer Student Scholarship

To review the outcome of patients with deep infection using a new 2-stage revision technique.

A management plan consisting of initial debridement, insertion of antibiotic spacers and 2 weeks of intravenous antibiotics is currently used. No further antibiotics are given systemically. If blood tests are satisfactory at 12 weeks, reimplantation occurs. Patients are encouraged to partially weight-bear and perform a range of motion exercises with their spacers in place. The necessary data has been prospectively collected to identify predictors of success.

Thirty four patients have been identified and fully followed up for more than 1 year. 27 patients have over 2 years of follow-up. When looking at all of the patients we have achieved an 82% success rate. For patients whose only previous major surgery was their arthroplasty this rises to 90%. Where multiple surgeries have been undertaken this falls to 73%. All of the peri-operative investigations have been reviewed and whilst they have a good negative predictive value they are not specific enough to alter practice.

Conclusions: Short courses of parenteral treatment can produce comparable results to previously- published series when treating deep infection after knee replacement. There seems to be a failure rate that is difficult to avoid associated with chronic, multiple revision cases.

This randomized clinical trial compares fixed- and mobile-bearing total knee prostheses in terms of the patients’ clinical outcome parameters (Knee Society Clinical Rating, WOMAC, SF-12), range of motion and performance during gait analysis for level-ground walking. Our results show no significant differences in the clinical outcomes and gait performance of the fixed- and mobile-bearing total knee arthroplasties.

The purpose of this study was to compare the clinical outcomes and gait parameters of patients with a fixed-bearing or mobile-bearing total knee arthroplasty (TKA).

Fifty-five patients were entered into a prospective, randomized clinical trial comparing fixed- versus mobile-bearing TKAs (Genesis II, Smith & Nephew, Memphis, TN). From this patient population, fifteen fixed-bearing and fifteen mobile-bearing TKA patients were matched based on age, sex and BMI to undergo gait analysis. Patients performed trials of level-ground walking at a self-selected velocity while three-dimensional kinetic and kinematic data were collected.

The fixed-bearing and mobile-bearing TKA patient groups were comparable regarding Knee Society Clinical Rating (181 ± 22 versus 171 ± 28), WOMAC scores (7 ± 5 versus 9 ± 12), SF-12 and range of motion (121° ± 11° versus 125° ± 6°).

Patients with fixed- and mobile-bearing TKAs performed similarly in the gait analysis in terms of their velocity, percent weight acceptance in the operated versus the non-operated limb, peak flexion in stance and swing phases, the support moments and extension moments at the ankle, knee and hip. Decreased peak extension in the mid-stance and swing phases was observed in the operative limb versus the non-operative limb for both fixed- and mobile-bearing TKAs (P=0.02 and 0.04). Decreased peak extension was also observed during mid-stance and swing phases in the mobile-bearing TKAs versus the fixed-bearing TKAs (P=0.064 and 0.052).

Fixed-bearing and mobile-bearing TKAs perform similarly in terms of their clinical outcome measures and the kinetics and kinematics of level-ground walking.

Funding for this project obtained from Smith & Nephew, Memphis, TN.

This prospective randomized multicenter study compares two methods of bone defect treatment in tibial plateau fractures: a bioresorbable calcium phosphate paste (Alpha-BSM) that hardens at body temperature to give structural support versus Autogenous iliac bone graft (AIBG).

One hundred and eighteen patients were enrolled with a 2:1 randomization, Alpha-BSM to AIBG. There was a significant increased rate of non-graft related adverse affects and a higher rate of late articular subsidence (three to nine month period) in the AIBG group.

A bioresorbable calcium phosphate material is recommended in preference to the gold standard of AIBG for bone defects in tibial plateau fractures.

This prospective randomized multicenter study was undertaken to compare two methods of bone defect treatment: a bioresorbable calcium phosphate paste (Alpha-BSM –DePuy, Warsaw, IN) that hardens at body temperature to give structural support and is gradually resorbed by a cell-mediated bone regenerating mechanism versus Autogenous iliac bone graft (AIBG).

One hundred and eighteen adult acute closed tibial plateau fractures, Schatzker grade two to six were enrolled prospectively from thirteen study sites in North America from 1999 to 2002. Randomization occurred at surgery with a FDA recommendation of a 2–1 ratio, Alpha BSM (seventy-eight fractures) to AIBG (forty fractures). Only internal fixation with standard plate and screw constructs was permitted. Follow-up included standard radiographs and functional studies at one year, with a radiologist providing independent radiographic review.

The two groups exhibited no significant differences in randomization as to age, sex, race, fracture patterns or fracture healing. There was however, a significant increased rate of non-graft related adverse affects in the AIBG group. There was an unexpected significant finding of a higher rate of late articular subsidence in the three to nine month period in the AIBG group.

Recommendations for the use of AIBG for bone defects in tibial plateau fractures should be discouraged in favor of bioresorbable calcium phosphate material with the properties of Alpha BSM. We believe further randomized studies using AIBG as a control group for bone defect support of articular fractures are unjustified.

A bioresorbable calcium phosphate material is recommended in preference to the gold standard of AIBG for bone defects in tibial plateau fractures.

Funding: DePuy, Warsaw, IN.

Measures of lower limb alignment and knee joint load during walking were evaluated before and six months after medial opening wedge high tibial osteotomy (HTO) in ninety-five patients with knee medial compartment osteoarthritis (OA). Full-length standing radiographs were used to calculate the mechanical axis angle, and a gait analysis was performed to calculate the external adduction moment about the knee. Results indicated significant decreases in mechanical axis angle and peak adduction moment. These findings provide an indication of the early success of HTO in reducing the extent of lower limb malalignment and knee joint load during walking.

Medial opening wedge high tibial osteotomy (HTO) is intended to correct lower limb malalignment, resulting in decreased medial knee joint load and improved function. Due to the potential for the amount of alignment correction to change over time after surgery, frequent follow-up evaluations are encouraged.

To evaluate the early changes in lower limb alignment and medial knee joint load experienced during walking after medial opening wedge HTO.

Ninety-five patients (seventy-nine males, sixteen females; age range = 21–76 years; BMI range = 18.0–38.5) with knee joint OA affecting primarily the medial compartment underwent radiographic and gait analyses pre-surgically and six months following HTO. Full-length standing radiographs were obtained on both occasions and used to measure the static mechanical axis angle. Three-dimensional kinetic and kinematic data were also collected and combined to calculate the external knee joint adduction moment, an indirect measure of knee joint load. Paired t-tests indicated the mechanical axis angle (mean decrease = 8.32 degrees, 95% CI = 7.54,9.10) and peak external knee joint adduction moment (mean decrease = 1.61%BW*ht, 95% CI = 1.25,1.95) significantly decreased post-operatively (p< 0.001). These results indicate less varus angulation and reduced medial knee joint load following HTO.

These preliminary findings suggest that medial opening wedge HTO is an effective surgical treatment for improving alignment and reducing knee joint load.

Although these early results are promising, future research is required to determine the long-term success of this surgery in the treatment of knee OA.

Funding:

CIHR, NSERC, Arthrex Inc.

The peak external knee adduction moment during walking gait has been proposed to be a clinically useful measure of dynamic knee joint load in patients with knee osteoarthritis. However, there is limited information about the reliability of this measure, or its ability to detect change. The test-retest reliability and sensitivity to change of peak knee adduction moments were evaluated in thirty patients with varus gonarthrosis. Indices of relative and absolute reliability were excellent (intra-class correlation coefficient = 0.85, standard error of measurement = 0.36 % BW*Ht), and the sensitivity to change following high tibial osteotomy was high (standardized response mean = 1.2).

To estimate the test-retest reliability, measurement error and sensitivity to change of the peak knee adduction moment during gait.

Thirty patients (44”11 yrs, 1.7”0.09 m, 87”20 kg, twenty males, ten females) with varus gonarthrosis underwent gait analyses on two pre-operative test occasions within one week, and on a third test occasion six months after medial opening wedge high tibial osteotomy. Three-dimensional kinematic and kinetic gait data were collected during self-paced walking and used to calculate the peak knee adduction moment.

An intraclass correlation coefficient of 0.85 (95%CI: 0.71, 0.93) indicated excellent relative reliability, and a standard error of measurement of 0.36 %BW*Ht (95%CI: 0.29, 0.49) indicated low measurement error. The peak knee adduction moment after surgery (1.66”0.72 %BW*Ht) was significantly (p< 0.001) lower than before surgery (2.58”0.72 %BW*Ht). A standardized response mean of 1.2 (95%CI: 0.77, 1.6) indicated the size of this change was large.

Based on 95% confidence levels, these results suggest the error in an individual’s peak knee adduction moment at one point in time is 0.70 % BW*Ht, the minimal detectable change in an individual’s peak adduction moment is 1.0 %BW*Ht, and it is sensitive to change following treatment.

The peak knee adduction moment during gait has appropriate reliability for use in studies evaluating the effect of treatments intended to decrease the load on the knee. When considering measurement error, the knee adduction moment is also appropriate for clinical use in evaluating change in individual patients.

Funding: CIHR, Arthrex Inc.

The Charnley Elite femoral component was first introduced in 1992 as a new design variant of the original Charnley femoral component (De Puy, Leeds, UK) with modified neck and stem geometry. The original component had undergone few changes in nearly forty years and has excellent long-term results. Early migration of the new stem design was determined by Roentgen Stereophotogrammetric Analysis (RSA)1. Rapid early migration of a component relative to the bone, measured by RSA, is predictive of subsequent aseptic loosening for a number of femoral stems. As there was rapid early migration and rotation of the Charnley Elite stem, we predicted that the long-term results would be poor. An outcome assessment is indicated as stems of this type are still being implanted.

One hundred Charnley Elite stems, implanted in our centre between 1994 and 1997 were included in a prospective, cross-sectional follow-up study. Outcome measures include validated clinical scores (Charnley hip score, Harris hip score and Oxford hip score) and radiological scores (Gruen classification) as well as revision rates over the past 10 years.

The clinical follow-up supports the RSA predictions of early failure of the Charnley Elite femoral stem.

Introduction: The Cambridge Acetabular cup is a unique, uncemented prosthesis that has been designed to transmit load to the supporting bone using a flexible material, carbon fibre reinforced polybutyleneterephthalate (CFRPBT). This should significantly reduce bone loss and provide long term stability. The cup consists of a ultra high molecular weight polyethylene liner within a carbon fibre composite backing that was tested with either a plasma sprayed HA coating or with the coating removed. The cup is a horseshoe shaped insert of similar thickness to the cartilage layer and transmits force only to the regions of the acetabulum originally covered with cartilage. The purpose of this study was to evaluate the response of bone and surrounding tissues to the presence of the cup in retrieved human specimens.

Methods: We examined 12 cementless Cambridge acetabular implants that were retrieved at autopsy between 2 and 84 months following surgery. Nine of the implants were coated with HA and three were uncoated. The implant and the surrounding bone were fixed, dehydrated and embedded in polymethylmethacrylate. Sections were cut parallel to the opening of the cup and in two different planes diagonally through the cup. The sections were surface stained with toluidine blue and examined by light microscopy. Image analysis was used to measure the percentage of bone apposition to the implant, the area of bone and fibrous tissue around the implant and the thickness of hydroxyapatite coating.

Results: All 9 HA coated implants showed good bone contact with a mean bone apposition and standard deviation of 50.9% +/− 17.5%. The thickness of the HA coating decreased with time and where this was occurring bone remodelling was seen adjacent to the HA surface. However, even in specimens where the HA coating had been removed completely good bone apposition to the CFRPBT remained. Bone marrow was seen apposed to the implant surface where HA and bone had both been resorbed with little or no fibrous tissue. The uncoated implants showed significantly less bone apposition than the HA coated specimens, mean 11.4% +/− 9.9%(p < 0.01) and significant amounts of fibrous tissue at the interface.

Discussion: The results of this study indicate that the anatomic design of the Cambridge Cup with a flexible CFRPBT backing and HA coating encourages good bone apposition. In the absence of HA the results are generally poor with less bone apposition and often a fibrous membrane at the implant surface. There was a decrease in HA thickness with time in situ and cell mediated bone remodelling seems to be the most likely explanation of the HA loss. However, good bone apposition was seen to the CFRPBT surface even after complete HA resorption in contrast to the uncoated specimens. Though the mean bone apposition percentage to the HA coated implants declined with time, the bone was replaced by marrow apposed to the implant surface. This is in contrast to the uncoated implants where fibrous tissue becomes apposed to the implant surface. We believe this is due to micro-motion occurring at the bone implant interface. The HA coating appears necessary to provide good initial bone bonding to the implant surface that is maintained even after complete loss of HA.

Introduction: The assessment of bone age using the standard Gruel and Pyle chart based on hand and wrist radiographs is usually carried out by Senior Radiologists. We performed a study to look at both intra and inter observer variability with different grades of clinicians.

Materials and Methods: 30 sets of wrist radiographs were selected at random. The investigators included a Senior Radiographer, a Consultant and Registrar Radiologist an Orthopaedic Consultant and Senior Orthopaedic Fellow.

Discussion: The Radiology team appear to be more consistent in their readings for the assessment of skeletal bone age than the Orthopaedic team. Howevr, it is interesting to note that although the Orthopaedic team are less consistent, when looking at the inter-observer variability, it suggests that both teams are equally well equipped to perform the task.

Conclusion: Our study suggests that we should not cross professional boundaries. Render unto Caeser what is Ceaser’s!

Introduction: Autologous Chondrocyte Implantation (ACI) was first described in 1994(1) and has become an increasingly widely used treatment for chondral defects in the knee. The intention of this study was to identify which patient and/or surgical factors affect clinical outcome. In order to do this, a multicentre database of patients treated with ACI was established.

Methods: Four European centres collaborating in the EuroCell project (2) contributed data. These centres have historically used different outcome measures to follow up their patients. In order to analyse this data, a method of z-transformation was used to standardise the clinical scores. This has allowed a large number of patients to be investigated even when different scores have been used. A panel of predictor variables was agreed relating to patient factors and operative technique. Linear multiple regression analysis was performed to determine which predictor variables significantly influenced clinical outcome.

Results: A total of 284 patient datasets from four centres were investigated with 1 to 10 year follow-up. In 213 datasets the Modified Cincinnati (Noyes) clinician evaluation was used (3). The remaining 73 patients had outcome data measured with the modified Lysholm score (4). Outcome was defined as the change in score to latest follow-up. Z-transformation (z-change) was performed for each score type. The regression model was: z-change = − 0.11 − 0.5*z-preop − 0.43*R4 + 0 .30*OC + 0.20*FC (R2=0.30) The regression analysis showed that the factors which affected outcome were one centre (R4), pre-operative score (z-preop), osteochondral defects (OC), and lesions of the femoral condyle (FC). Factors which were found not to affect outcome included the age of the patient, size of the defect treated, number of defects treated and time to follow-up. Variations in operative technique, including the location of the cartilage harvest, the use of fibrin sealant and the timing of patch placement, were not found to have an effect on clinical outcome.

Conclusions: The method of z-transformation is a useful way of compiling multicentre data where different outcome measures have been used. This has allowed a large dataset to be compiled and factors which influence clinical outcome to be identified.

Introduction: Joint replacement surgery is one of the most common operations that take place in United Kingdom. The major problem in total hip arthroplasty is the generation of particulate wear debris and the subsequent biological responses. Wear debris induces osteolysis and a subsequent failure of the implant that lead to the liberation of greater quantities of particulate and soluble debris to bone marrow, blood, lymph nodes, liver and spleen. Recently, it has been suggested that these adverse effects depend not only on the chemical composition but also on the particulate nature of the material (size and shape). Particle size has been shown to influence the inflammatory response of macrophages to wear debris. This study evaluated whether particle size also influences the viability and mutagenic damage.

Methods: Cobalt chrome alloy particles of two sizes (large 2.9±1.1μm, small 0.07±0.04 μm) were generated and characterised by Scanning Electron Microscopy. Different concentrations of particles were added to primary human fibroblasts in tissue culture. The release of cytokines in the medium was assayed by Enzyme-Linked ImunnoSorbent Assay (ELISA). Cell viability was determined by MTT conversion and the degree of DNA damage was quantitatively analysed by the Alkaline Single Cell Gel Electrophoresis (COMET) assay with image analysis.

Results: Small particles initialise DNA damage at much lower volumetric concentrations (0.05 and 0.5 μm³/cell) than larger particles (500 μm³/cell). The difference in the doses was approximately related to the difference in surface area of the particles. DNA damage was related to a delayed decrease in cell viability, which was noted after three days of exposure.

In contrast, the release of the inflammatory cytokine TNF-α and the multifunctional growth factor TGF-β-2 occurred at lower doses (0.0005 to 5 μm³/cell for TNF-α and 0.5 to 50 μm³/cell for TGF-β-2). No release of IL-6 was detected at any dose. Only growth factor FGF-23 was increased in similar pattern to the DNA damage.

Conclusions: This study has demonstrated important differences between the mutagenicity, toxicity and inflammatory potential of small (nanometre sized) and large (micrometer sized) chrome particles.

Introduction: Several recent studies have highlighted the influence of topographical features on the response of cells to biomaterial surfaces, both in terms of their adhesion, morphology and gene expression. Initial cell adhesion events are believed to be pivotal in dictating subsequent host response to implant materials and therefore understanding the mechansims that regulate these events is fundemental to the design and engineering of the next generation of biomaterials. In our studies we evaluated the adhesion associated events of osteoblasts on four orthopaedic metals, each produced to the same surface finnish. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to determine the nanometre scale topography and immunofluorescence microscopy and image analysis performed to evaluate cell morphology.

Methods: Vitallium, titanium grade 2 (Ti2), Ti6Al4V and TM2F discs were prepared by Stryker, machined and finished to 1 micron. SEM and AFM were then used to analyse surface topography. Rat primary osteoblasts were then seeded at low density onto the metal discs and allowed to adhere and spread for 24 hours. The cells where fixed and focal adhesions stained with an anti-vinculin Mab. The actin cytoskeleton was counterstained with TRITC phalloidin and nuclei stained with DAPI. Images where captured on both a standard epiflourescence microscope and a confocal microscope. Image analysis was performed using ScionImage^TM to determine cell area, major X/Y axis lengths and numbers of focal adhesions per cell.

Results: Gross observation of all samples revealed a perfectly smooth and flat surface. SEM and AFM analysis showed that at the nanometre scale each exhibited varying degrees of surface roughness. Vitallium was the smoothest with scratches a few nanometres deep running across the surface. In contrast Ti6Al4V, Ti2 and TM2F had increasing degrees of surface roughness, each with details that measured up to a few microns in height.

We measured 1: the area occupied by a cell and 2: the number of focal adhesions per cell. The largest values of osteoblastic cell area were seen with the smoother vitallium surface. In contrast, samples with more numerous and larger surface features resulted in the osteoblasts covering a smaller area and being confined by topographical elements (Ti2> TM2F> Ti6Al4V). In terms of adhesion, there were generally more focal adhesions per cell on rougher surfaces (Ti6Al4V> TM2F> Vitallium> Ti2).

Conclusions: The different nanometre scale features introduced through the manufacturing process of different orthopaedic implant materials influence the adhesion and cell morphology of osteoblast cells within the first 24 hours of contact. This may have consequences for later differentiation and function of these cells.

Aim of the study: To evaluate the final outcome following joint distraction and reconstruction in patients with complex knee contractures in a select group with varied aetiology.

Materials and methods: Retrospective study of six patients (nine knees, 3 bilateral) with severe knee flexion contractures treated by gradual distraction using ring fixators. Most cases were syndromic or arthrogrypotic.. Case notes and radiographs were reviewed to assess the mobility and functional range of motion before and after the procedure.

Results: Staged procedures was carried out in 6 out of 9 knees accompanied by soft tissue releases, realignment of extensor mechanism and bony and joint realignment. The average age at operation was nine years and nine months and the mean follow up was 53 months. The average time spent in frame was 20 weeks. The correction was graded as good to excellent in 5 knees, fair in 1 and poor in 3 knees. The total arc of motion remained unchanged though the functional range of movement improved. The mobility improved significantly in most patients who were independent walkers with or without splints. Complications were of rebound phenomenon after frame removal in arthrogrypotic children, transient neuropraxia of common peroneal nerve in 2 epiphyseal separation in one and 3 sustained undisplaced fractures during mechanical distraction.

Conclusion: Syndromic and arthrogrypotic knee contractures are difficult to treat due to their severity and complexity. Planned staged procedures with joint distraction, patellar and bony realignment can produce satisfactory outcome in most making them functional independent ambulators.

Developments in motion analysis technology over the last two decades have enhanced our understanding of human locomotion. However, such advances in knowledge are futile if no practical use is made of them. Scientists and engineers need to make the most of these developments by forging stronger links with orthopaedic surgeons and applying further advances in their knowledge to clinical problems for the long-term benefit of patients. This need has been identified by many in the field of biomechanics and a “serious attempt [has been made] to take gait analysis out of the research laboratory and into the clinic” (Whittle, 1996 pp.58). For this reason, the aim of this research is to develop an objective and quantitative classification tool that uses motion analysis to aid orthopaedic surgeons and therapists in making clinical decisions. Practical applications of this tool would include joint degeneration monitoring; diagnostics; outcome prediction for surgical intervention; post-operative monitoring and functional analysis of joint prosthesis design. The classification tool (Jones, 2004), based around the Dempster-Shafer theory, is logical and visual; as the progression from obtaining clinically relevant measurements to making a decision can be clearly followed. The current study applies the tool to identify knee osteoarthritis (OA) and post-operative recovery following total knee replacement (TKR) surgery. Knee function data from 42 patients (22 OA and 20 normal (NL)) were collected during a clinical knee trial (Holt et al., 2000). Nine of the OA patients were followed at 3 stages following TKR surgery. Using the tool, a subject’s knee function data are transformed into a set of belief values: a level of belief that the subject has OA knee function, a level of belief that the subject has NL knee function and an associated level of uncertainty. These three belief values are then characterized in a way that enables the final classification of the subject, and the variables contributing to it, to be represented visually. Initial studies using this technique have provided encouraging results for accuracy, validity and clinical relevance (Jones, 2004). The tool was able to differentiate between the characteristics of NL and OA knee function with 98% accuracy. The belief values and simple visual output showed the variation in the extent to which patients had:

developed OA and;

Furthermore, the visual output enabled straightforward comparison between subjects and indicated the variables that were most influential in the decision making process for comparison with clinical observations and quality of life scores. The tool is generic, and, as such, would be applicable to a wide range of pathological classification and predictive problems.

Results Holt, C.A. et al. (2000). Computer Methods in Biomechanics and Biomedical Engineering 3. Lisbon. Gordon and Breach Science Publishers SA. pp.289–294. Jones L. (2004). The development of a novel method for the classification of osteoarthritic and normal knee function. PhD Thesis. Cardiff University Whittle, M.W. (1996). Gait analysis: an introduction. 2nd Edition. Oxford; Boston: Butterworth-Heinemann.

Introduction: The design philosophy of polished tapered THR stems, such as the Exeter, intend for them to migrate distally within the cement mantle. In addition it is likely that micromotion occurs as a result of functional activity. The pattern of induced stresses will be a function of stem geometry & surface finish, as well as applied loading. Aim: To investigate the stresses induced in the cement mantle of a polished tapered THR stem during functional activity.

Method: Using Roentgen Stereophotogrammetric Analysis (RSA) dynamically induced micro-motion (DIMM) was measured in 21 patients implanted with Exeter stems. DIMM was measured as the difference in stem position in going from double to single leg stance on the operated limb. All subjects were measured 3 months post-operatively. A finite element (FE) model of the femur, including all muscles was used to investigate the stress distribution within the cement; contact was modelled with sliding elements allowing separation. The model was validated by comparison to the DIMM measurements.

Results: The Exeter stem demonstrated significant DIMM(p < 0.017), the average motions are given in the table below. The FE model, with sliding contacts was able to predict similar distal migration of the head. The peak minimum principal stress in the mantle was approx 33MPa and occurred in the proximal medial region. Movements occurred at the stem/cement interface.

Discussion and Conclusion: It is possible to measure DIMM in the Exeter stem and combining this with FE modelling the mechanism of stress transfer between the stem and mantle can be investigated in a manner that can be validated.

Introduction A consensus exists regarding the optimal range of femoral cement mantle thickness in hip replacement. However, within this range surgical preferences differ, surgeons in Europe generally preferring thinner cement mantles whilst those in the US prefer a thicker mantle. For a given implant size, the rasps provided in the US for use with the Stanmore Hip are larger than those used in Europe, producing a thicker cement mantle. The integrity of the femoral cement is considered to be crucial to the long-term survival of cemented hip replacements. Previous studies have used cement cracking under fatigue loading as a comparative measure of implant survival. Damage accumulation levels between different implants are associated with clinical failure rates. The aim of this study was to compare the cracking behaviour of cement mantles of different thicknesses around Stanmore Hip replacements. We hypothesised that a thicker cement mantle would lead to reduced cement cracking.

Methods Ten synthetic femurs (Sawbones) were prepared following standard surgical practice for the Stan-more Hip. Five of these were rasped using the larger US rasp, and five using the European version. Stanmore Hip femoral components were then cemented into the femurs with Palacos-R cement and using a custom insertion rig to ensure good alignment and centralisation, confirmed by radiographs. The femurs were then cyclically loaded with an aggressive 4 kN stair-climbing load for 4 million cycles at 3 Hz. The femurs were sectioned at 5 mm intervals and dye penetrant used to highlight cement cracks. Image analysis software was used to measure cement thickness and crack lengths under light microscopy.

Results The minimum cement mantle thickness per section was found to average 0.8 mm and 2.0 mm for the thin and thick mantle groups respectively, measured around the proximal half of the implant. This was significantly different (p< 0.05). Cracks in the cement mantle were irregularly distributed along the length of the prostheses. We found no significant difference in either the total number or total length of cracks found in each group. These were investigated over the whole mantle and by Gruen Zone.

Discussion The geometric and mechanical properties of human femurs vary considerably, which might be expected to increase dramatically the scatter in any clinical trend relating cement thickness to cracking. Our study, using identical synthetic femurs and well-centralised prostheses to minimise experimental variability, found no difference in cracking. Given this experimental consistency, it is thought that there would be no clinically significant difference in cracking rates between different cement thicknesses within the normal range for the Stanmore Hip replacement. The Stanmore Hip is designed to minimise cement stress. A collar prevents subsidence-related hoop stresses, and smooth corners minimise stress concentration in the cement. It is likely that, for a sub-optimal implant design with higher stress risers, cement thickness might have a more noticeable effect on crack propagation.

Leucocytes represent a very important host defence against a number of invading pathogens and neoplasia. However, the activity of phagocytic leucocytes has been heavily implicated in the development of ischaemia-reperfusion injury, and as an aetiological factor in the pathology of other clinically important inflammatory conditions. Ischaemia-reperfusion injury occurs in diseases such as stroke and ischaemic heart disease (IHD), and during surgical procedures such as orthopaedic surgery. Investigations presented here employed a model of tourniquet-induced forearm ischaemia-reperfusion injury to investigate the effect on leucocyte adhesion and trapping (n=20). Neutrophil and monocyte leucocyte subpopulations were isolated by density gradient centrifugation techniques. Neutrophil and monocyte cell surface expression of the adhesion molecule CD11b was measured by labelling with fluorescent anti-CD11b monoclonal antibody via flow cytometry. Plasma concentrations of the soluble intercellular adhesion molecule-1 (sICAM-1) and soluble L-selectin (sL-selectin) adhesion molecules were measured using commercially available ELISA kits. Leucocyte trapping was investigated by measuring the concentration of leukocytes in venous blood leaving the arm. During ischaemia-reperfusion there was an increase in CD11b expression on neutrophils (p=0.040) and monocytes (p=0.049), a decrease in sL-selectin (p=0.387) and sICAM-1 (p=0.089) concentrations, and a decrease in peripheral blood leucocyte concentration (p=0.019). Evidence of increased leucocyte adhesion and trapping during ischaemia-reperfusion injury was supported by an increase in CD11b cell surface expression of neutrophils and monocytes. CD11b is expressed on phagocytic leucocytes and binds to ICAM-1 expressed on the surface of vascular endothelium. This increased expression of CD11b on leucocytes may therefore play a central role as the mechanism by which leucocyte trapping in the microcirculation occurs. The measured decrease in plasma concentration of sICAM-1 and sL-selectin suggests that these adhesion molecules retain their functional activity, and may bind to their corresponding cell surface ligands. It is therefore reasonable to believe that ICAM-1 expressed on the endothelium and L-selectin expressed on leucocytes is also binding to their corresponding cell surface ligands. A decrease in the number of leucocytes in the peripheral circulation may be due to increased trapping of leucocytes in the microcirculation. When leucocytes become trapped their concentration in blood leaving the microcirculation decreases, resulting in the measured decrease in leucocyte concentration. In conclusion, this study confirms the important role of leucocytes during ischaemia-reperfusion injury, which could allow for the possibility of future research that may provide therapeutic intervention for inflammatory conditions.

Aim: To report our experience and early results with the Ilizarov pelvic support realignment lengthening osteotomy for complex hip pathology in children.

Material & Methods: Between 1997 & 2004, seven children were treated with this technique and five have completed treatment. The treatment was undertaken for sequelae of DDH in 4 patients and septic arthritis in 1 patient. The median age of the patients was 13(10–17). There were 3 boys and 2 girls. The outcome assessment was performed using the Harris hip score, clinical and radiological parameters.

Results: 4 patients presented with hip instability, shortening of the lower limb, pain and restricted motion. The remaining patient presented with a nonfunctional ankylosis with shortening. The median time between the onset of symptoms and the operation was 3 years (2–5). The median preoperative leg-length discrepancy was 3 cm (2–4.5). The median fixator time was 5 months (3–6). The median follow-up was 24 months (9–72).

Patients had improvement of pain, posture, hip instability, walking ability and limb length discrepancy. The median lengthening of the femur was 3 cm (2–5). The mechanical axis was realigned in all patients. All patients were satisfied with the outcome. Planned secondary contra lateral epiphyseodesis was required to equalise leg length in 2 patients. Complications included a stiff knee (1) that required a Judet quadricepsplasty, premature consolidation (1) that required reosteotomy and knee subluxation (1) that required cross knee stabilisation.

Conclusion: This is a safe and reliable alternative option to joint replacement, Colonna arthroplasty and arthrodesis for the reconstruction of multiply operated complex hip pathology in children.

Purpose: The aim of this part retrospective and part prospective study was to establish the incidence of pinsite infections and assess evolution of changes in practice

Methods: Data was collected retrospectively and prospectively for pin site infections from the inception of limb reconstruction service viz. 1985 to January 2002. There were 812 patients, 1042 limb segments, and 9935 pins. The various external fixators used were limb reconstruction system (LRS) 549; Ilizarov 397; Sheffield ring fixator (SRF); Dynamic axial fixator (DAF) 35; LRS/Sequoia 8; LRS/Garche 7; and Pennig 5.

Results: The pin site infections were graded from 0 to 6 ( Saleh & Scott). There were no infections in 206 segments. The infection grade is shown below:

We changed our pin tract care practice from 1996. We had a significant decrease in pin tract infections since then (p< 0.0001). We also found that using Ilizarov wires had significantly less infections than with half pins used with monolateral fixators (p< 0.0001; linear trend, p= 0.0338). There were 48 patients that required hospital admissions for IV antibiotics. and of these 10 patients required debridement. There were no residual long lasting infections or chronic osteomyelitis.

Conclusion: Attention to detail in insertion of wires and half pins is crucial to avoid pin site infections. This audit supports the fact that external fixation is a safe method from the point of view of infection contrary to general belief.

Introduction: Prophylactic pinning of an asymptomatic hip in SCFE is controversial. Bone age has been used as evidence of future contralateral slip risk and used as an indication for such intervention. The efficacy of bone age assessment at predicting contralateral slip was tested in this study.

Patients and Methods: 18 Caucasian children prospectively had bone age assessment using wrist and hand x-rays when presenting with a unilateral SCFE. Patients and parents were informed about the chance of contralateral slip and risks of prophylactic fixation, and advised to attend hospital immediately on development of symptoms in contralateral hip. After in-situ fixation of the affected side prospective monitoring in outpatient department was performed. Surgical intervention was undertaken if the contralateral hip was symptomatic.

Results: Three children (2 boys) went on to develop to a contralateral slip at a mean of 20 months from initial presentation. 6 children (5 boys) were deemed at risk of contralateral slip due to a bone age below 12.5 years for boys and 10.5 for girls. Only one from this group developed a contralateral slip. The relative risk of proceeding to contralateral slip when the bone age is below the designated values was 1 (95% confidence interval of 0.1118 to 8.95).

Conclusion: Delayed bone age by itself is not a good predictor of future contralateral slip at initial presentation. Routine prophylactic pinning is not justified based on bone age alone, with the risks of surgical fixation it carries. Prospective long term longitudinal study is required.

Aims: The aims of this study were to evaluate the biomechanical properties and mode of failure of 4 methods of fixation used for hamstring tendon ACL grafts. The fixation methods investigated included titanium round headed cannulated interference (RCI) screws, bioabsorbable RCI screws, Endobuttons and Bollard fixation. It has been previously shown that a 2 strand tailored equine tendon-Soffix graft has equivalent biomechanical properties to a 4 strand human hamstring tendon-Soffix graft [1,2], therefore this model was used for the graft in the study.

Materials and Method: 32 stifle joints were obtained from skeletally mature pigs, the soft tissues were removed and the ACL and PCL were sacrificed. Tibial tunnel preparation was standardised using the Mayday Rhino horn jig to accurately position a guide wire. An 8 mm cannulated reamer was then used over the guide wire to create the final tibial tunnel. A back radiusing device was then placed into the tibial tunnel to chamfer the posterior margin of the tunnel exit to prevent abrasion and fretting of the graft. A 2 strand equine tendon-Soffix graft was then introduced into the tibial tunnel and secured with one of the four fixation methods. The proximal part of the graft was attached to the cross head of the materials testing machine using the Soffix. Five of each method of fixation were tested mechanically to failure and three of each method were cyclically loaded for 1000 cycles between 5 to 150 N, followed by 2000 cycles at 50 to 450 N.

Results: The mean ultimate tensile loads (UTL) were: titanium RCI screw = 444 N, bioabsorbable RCI screw = 668 N, Endobutton = 999 N and Bollard = 1153 N. The mode of failure for all RCI screws involved tendon slippage past the screw. Two Endobutton failures were encountered and one Bollard pull out occurred. Under cyclic loading conditions the titanium and bioabsorbable RCI screws failed rapidly after several hundred 5 to 150 N cycles due to tendon graft damage and progressive slippage. Both the Bollards and Endobuttons survived 1500 cycles at 50 to 450 N, with less tendon slippage occurring.

Conclusion: Titanium and bioabsorbable RCI screws provide poor initial fixation of tendon grafts used for ACL reconstruction, having significantly lower UTL’s than both Endobutton and Bollard fixation. Under cyclic loading titanium and bioabsorbable RCI screws fail rapidly due to progressive tendon slippage, whereas Bollards and Endobuttons survive cyclic loading. Both Bollard fixation and Endobuttons provide sufficiently high UTL’s and survive cyclic loading to allow early postoperative mobilisation and rehabilitation. Caution must be used in the early postoperative period when using interference screws to secure a hamstring tendon graft because progressive tendon slippage may result in excessive graft elongation and early clinical failure.

It is well appreciated that thigh pain following recent arthroplasty surgery is likely to be due to prosthetic loosening or infection. Both these sequelae can lead to periprosthetic fracture presenting complex challenges to even experienced surgeons.

Revision arthroplasty patients are prone to both fatigue and insufficiency fractures as they may have reduced bone stock after previous surgery and reduced bone density secondary to medical and immobility reasons. The post operative painfree condition will frequently permit early load bearing leading to a relatively rapid increase in activity and load bearing.

Fatigue fractures occur in bone of normal quality subject to abnormal cyclical overloading, leading to resorption and eventual failure, before adequate time has passed to permit adaptive remodelling. Insufficiency fractures occur when normal physiological loads are applied to bone of abnormal quality.

Surprisingly few periprosthetic stress fractures are reported in the literature but a series notes lateral tensile stress fractures associated with varus prosthetic alignment. These all occurred near the tip of the prosthesis.

The case of an unusual Gruen Zone 2, Vancouver B1 stress fracture, 9 months following revision arthroplasty is reported. Initially loosening was suspected due to the development of load bearing thigh pain. Plain radiography revealed the development of a dreaded black line, consistent with a stress fracture. Bone scintigraphy revealed the typical appearance of a stress fracture in the absence of loosening or infection.

The unusual location of this stress fracture allowed consideration of conservative non weight bearing management which lead to the alleviation of symptoms rather than further revision surgery.

This report illustrates this unusual stress fracture and highlights the importance of careful loading practises to permit adequate remodelling following complex revision surgery.

The aim of this study was to determine the inter and intra observer reliability of ultrasound measurements in treated unstable neonatal hips and whether ultrasound measurements correlate with radiological outcome at 6 months.

Sixty-four babies treated from birth with a Pavlik harness for neonatal hip instability were scanned at 2 and 6 weeks. The α and β angles of Graf, the combined (H) angle of Hosny and the femoral head coverage (FHC) were measured by 3 observers and inter-observer and intra-observer repeatability co-efficients calculated using 95% confidence limits. Hips were categorized as normal, abnormal or borderline for each parameter and Kappa values calculated. A stepwise linear regression analysis was performed to assess any relationship between ultrasound measurements at 2 or 6 weeks and outcome as determined by acetabular index at 6 months.

Seven hundred and ninety two sets of measurements were made from 248 scans. The α angle had the smallest interobserver range (17°), the H angle range was 21°and the β angle 28°. Kappa values showed good agreement for FHC and β angle. The mean acetabular index of all hips at 6 months was 26° (sd 4.9). The acetabular index was 30° or greater in 24 hips (18 babies) despite prolonged splintage in 9 hips (6 babies). The FHC at 6 weeks was predictive of acetabular index at 6 months (regression coefficient −0.27, 95% CI −0.42 to −0.12, p< 0.001)

We recommend the FHC as being reproducible, useful and predictive of outcome in neonatal hips treated for instability.

The aim was to compare the initial pull out strengths of various interference screw devices used for tibial fixation of hamstring grafts and the effect of concentric or eccentric screw position.

Quadrupled tendon grafts were harvested from freshly killed sheep. The grafts were then prepared and fixed in the distal femur using various devices (Intrafix, RCI screw, Wedge screw +/− transfix pin, screw and post) in both concentric and eccentric positions. A single load to failure test was then performed.

The highest pull out strength was with the Intrafix device inserted concentrically (mean 941N). This was significantly higher than the wedge screw inserted concentrically (737N) (p=0.015). This in turn had significantly greater initial pull out strength than the wedge eccentric with post or pin (p=0.03) and the RCI screw (464N) (p=0.00036).

In this sheep model the Intrafix device inserted concentrically had a significantly greater initial pull-out strength than the other interference screws tested. Concentric positioning of an interference screw gave significantly greater initial pullout strength of a quadruple hamstring graft than eccentric positioning. Addition of a cross pin or post made no difference to initial pullout strength.

Introduction: The response of osteoblasts to dexamethasone is dose-dependent. While low doses are used to stimulate osteoblasts to maintain their phenotype, high doses are cytotoxic. The purpose of this study was to test the hypothesis that mechanical stimulation alters the response of osteoblast-like cells to dexamethasone.

Materials & Methods: MG-63 cells were propagated on 6-well Flexcell plates (flexible silicone membranes) under standard culture conditions. One half of the plates were subjected to biaxial strain at a frequency of 0.5 Hz through an imposed vacuum pressure of -7kPa (~1% stretch; 0.01 strain) for 42 hours using the Flexercell Apparatus. Replicate samples were maintained under static conditions. Simultaneously, the cells were exposed to either 0, .001, .01, or .1 nM of dexamethasone. The wells were then spiked with tritiated thymidine for 6 hours. The results were normalized to the control values. Triplicate wells were included for each experimental condition; and the experiment was repeated four times. Data were analyzed by JMP statistical package (SAS).

Results: Increasing doses of dexamethasone resulted in decreasing cellular proliferation. For the unflexed cells, we noted the following reduction in proliferative capacity: 0.86% ± 0.09 (.001nM), 0.50% ± 0.07 (.01nM), and 0.39% ± 0.07 (.1nM). Similar results were observed for the cells exposed to cyclic loading: 0.89% ± 0.12 (.001nM), 0.52% ± 0.08 (.01nM), and 0.47% ± 0.07 (.1nM).

Discussion: Our results confirmed the work of others that there is a decrease in the proliferation of osteoblasts (incubated under static conditions) when exposed to high levels of dexamethasone. Although cyclic loading had no effect on the proliferative response of osteoblasts to dexamethasone, it may still have had an effect on cellular metabolism or function, which remains to be evaluated.

Background: More patients are turning to the Internet for health-related information. Studies indicate that this information is being used to make decisions about their management. The aim of this study was to assess the information available specific to scoliosis on the Web using four common search engines.

Methods: Four search engines (Google, Yahoo, Hotmail and Ask Jeeves) were used in scanning the Web for the following key word- “Scoliosis”. Both U.K. only and World Wide sites were accessed. Four Spinal Surgery Consultants independently graded each site for layout, content, relevance to patients as opposed to medical professionals, ease of use and links to other sites. Each point was marked on a scale of 0–2 and a total of 10 points available. Web sites were assessed via U.K. search engines and forty via World Wide search engines. Good was awarded to a site with a score of 7–10; an average awarded for a score of 4–7 and poor was given to a site with a score of 0–4.

Results: For the U.K. search engines, twenty sites were evaluated and five common sites identified (spineuniverse.com, S.A.U.K.org, orthoteers.co.uk, B.O.A.ac. uk and scoilosis.info). From these sites only two were given a rating of good. For the World Wide Web search engines eighteen sites evaluated and seven common sites identified (SRS, spineuniverse.com, scoliosis.org, orthinfo.aaos.org, iscoliosis.com, scoliosisrx.com and scoliosis-world.com). From these sites four were given a rating of good. It was evident that the Scoliosis Association of United Kingdom did not appear in three of the search engines but only in Hotmail.

Conclusion: These results suggest that there are good sites available for patients to access information with regards to their condition and treatment options but there are also very poor sites available where incorrect information is available. Commonly, unfamiliar users of the Web will not search U.K. sites specifically and could easily miss the S.A.U.K. site, which is an excellent site and was one of the two sites via the U.K. search engine awarded a good score. Obviously, there were more good sites via the World Wide Web due to the American healthcare system. We recommend that leaflets should be available to parents and patients with scoliosis with information from the BSS of the condition and available Web sites with good ratings. Also we recommend that these sites be linked to the Royal College of General Practitioners Web site to provide reference on good practice.