A retrospective review was conducted of patients undergoing either total hip replacement or hemiarthroplasty for intra-capsular neck of femur fractures between April 2013 and April 2014; identified from entries into the National Hip Fracture Database. PACS and the electronic database encompassing operation notes and discharge summaries were reviewed. 309 patients were identified, 3 of whom fractured both hips during the study period giving a total of 312 operations. The age range was 46 to 102 with a mean age of 82. 59 cemented bipolar hemiarthroplasties, 143 cemented unipolar hemiarthroplasties, 2 uncemented hemiarthroplasties and 108 total hip replacements were performed. 10 patients required further operations. There have been 5 dislocations: 2 underwent MUA only, 2 treated by excision arthroplasty and 1 converted to THR. 1 patient developed a haematoma requiring wound washout. There were 4 wound infections - 1 treated by a washout, 2 by excision arthroplasty and one patient has undergone first stage revision; an overall reoperation rate of 3.2% comparing well with data published elsewhere.

Inherent disadvantages of reverse shoulder arthroplasty designs based on the Grammont concept have raised a renewed interest in less-medialised designs and techniques. The aim of this study was to evaluate the outcome of reverse shoulder arthroplasty (RSA) with the fully-constrained, less-medialised, Bayley–Walker prosthesis performed for the treatment of rotator-cuff-deficient shoulders with glenohumeral arthritis. A total of 97 arthroplasties in 92 patients (53 women and 44 men, mean age 67 years (standard deviation (sd) 10, (49 to 85)) were retrospectively reviewed at a mean follow-up of 50 months ((sd 25) (24 to 96)). The mean Oxford shoulder score and subjective shoulder value improved from 47 (sd 9) and 24 points (sd 18) respectively before surgery to 28 (sd 11) and 61 (sd 24) points after surgery (p <  0.001). The mean pain at rest decreased from 5.3 (sd 2.8) to 1.5 (sd 2.3) (p < 0.001). The mean active forward elevation and external rotation increased from 42^°(sd 30) and 9^° (sd 15) respectively pre-operatively to 78^° (sd 39) and 24^° (sd 17) post-operatively (p < 0.001). A total of 20 patients required further surgery for complications; 13 required revision of components. No patient developed scapular notching.

The Bayley–Walker prosthesis provides reliable pain relief and reasonable functional improvement for patients with symptomatic cuff-deficient shoulders. Compared with other designs of RSA, it offers a modest improvement in forward elevation, but restores external rotation to some extent and prevents scapular notching. A longer follow-up is required to assess the survival of the prosthesis and the clinical performance over time.

Cite this article: Bone Joint J 2014;96-B:936–42.

Malformation and hypoplasia of the clavicle can result in pain, impaired function, restricted shoulder movement, subjective feeling of instability and cosmetic deformity. There are no reports of clavicle lengthening by osteotomy and distraction osteogenesis (DO). This is a retrospective review of 5 patients (7 clavicles) who underwent clavicle lengthening by DO using a monolateral external fixator for clavicular hypoplasia. There were 3 males and 2 females with mean age 15 years (9 to 23) and mean follow-up 21 months (8 to 51). Preoperative diagnoses included Klippel-Feil syndrome, cleidocranial dysplasia with torticollis, congenital myopathy and Noonans syndrome and obstetric brachial plexus injury. Mean length gained was 31 mm (15 to 41) which represens an average of 24.7% of overall bone length. Mean time in fixator was 174 days (161 to 263) and mean external fixation index was 56 days/cm. Two patients required internal fixation following fixator removal to consolidate union and one required additional internal fixation for atrophic regenerate. Mean preoperative oxford shoulder score improved from 28.5 to 41 and all patients were extremely satisfied with their result. Two patients developed pin site infections. Clavicular lengthening by distraction osteogenesis for congenital clavicular hypoplasia is a previously unreported technique that enables gradual correction of deformity without risking brachial plexus traction injury following acute correction. It has the potential to improve shoulder pain, function, range of movement and cosmesis. Distraction ≥25% of overall bone length may require additional plate fixation to consolidate union.

Reverse polarity total shoulder arthroplasty (RTSA) has gained popularity over recent years for the treatment of the painful cuff deficient shoulder. Although proposed over 20 years ago and despite good clinical outcomes the RTSA has struggled to gain popularity due to reported high levels of complications.

One such complication is post-operative instability with frequencies of up to 30% (De Wilde 2002). The Bayley-Walker RTSA was designed specifically for patients with difficult reconstruction problems in whom an unconstrained prosthesis would not offer sufficient stability. It is a reverse anatomy fixed fulcrum constrained prosthesis. The glenoid component has a long HA-coated tapered helical screw, with large pitch and depth, fixation is augmented by a grooved HA coated glenoid plate.

The purpose of this study was to review the clinical experience from The Royal National Orthopaedic Hospital Stanmore and to ascertain the rate of glenoid component loosening. We also carried out a radiographic review to correlate loosening with patterns of lucency on post-operative radiographs. One hundred and five B-W TSRs in 103 patients were included, 24% of which were performed as revision of previous failed arthroplasty. In total, 8/105 glenoids required revision. Of those eight patients, two were cases of septic loosening. Of all nine specified areas of glenoid, tip lucency on x-ray appeared to be most strongly associated with need for glenoid revision. 5/9 cases with tip lucency progressed to loosening of the glenoid. Where tip lucency was not seen, 93/96 glenoid components remained secure, giving tip lucency a negative predictive value of 97%. Excluding the two infected cases, the glenoid remained secure in 97/103 patients undergoing BW-TSR with follow-up up to 13 years. The BW-TSR is a satisfactory and durable solution to the cuff-deficient shoulder in variety of challenging groups including younger patients and as a salvage procedure following failed, cuff-deficient arthroplasty.

With an increasing ageing population and a rise in the number of primary hip arthroplasty, peri-prosthetic fracture (PPF) reconstructive surgery is becoming more commonplace. The Swedish National Hip Registry reported that, in 2002, 5.1% of primary total hip replacements required revision due to PPF. Laboratory studies have indicated that age, bone quality and BMI all contribute to an increased risk of PPF. Osteolysis and aseptic loosening contribute to the formation of loosening zones as described by Gruen, with subsequent increased risk of fracture. The aim of the study was to identify significant risk factors for PPF in patients who have undergone primary total hip replacement (THR).

Logbooks of three Consultant hip surgeons were filtered for patients who had THR-PPF fixation subsequent to trauma. Risk factors evaluated included sex, age, bone density (Singhs index), loosening zones, Vancouver classification, prosthesis stem angle relative to the axis of the femur, and length of time from THR to fracture. A control group of uncomplicated primary THR patients was also scrutinised.

Forty-six PPF were identified representing 2.59% of THR workload. The male: female ratios in both groups were not significantly different (1:1.27 and 1:1.14 respectively). Average age of PPF was 72.1, which was significantly older than the control group (54.7, p>0.05). The commonest type of PPF was Vancouver type B. Whilst stem position in the AP plane was similar in both groups, in lateral views the PPF stem angle demonstrated significant antero-grade leg position compared to the non-PPF group (p.0.05). The PPF group demonstrated a greater number of loosening zones in pre-fracture radiographs compared to the control group (2.59 and 1.39 respectively, p>0.05)

Our workload from PPF reflects that seen in Europe. Age, stem position and the degree of stem loosening appear to contribute to the risk of a peri-prosthetic fracture.

Introduction: The advantages of metal on metal bearings (MoM) include improved wear characteristics and lower dislocation rate. Metal sensitivity and Aseptic Lymphocyte Dominated Vasculitis Associated Lesion (ALVAL) reaction are becoming increasingly recognised. The BOA has recently issued a statement regarding MoM bearings. They suggested that any revisions for symptoms of pain and soft tissue reaction should be reported to the MHRA and histological specimens forwarded to the Stanmore Retrieval Centre.

Methods and results: We report four patients (all females), who presented with late dislocation of a large diameter MoM bearing (three following total hip replacements and one following resurfacing). They all made good initial recovery with complete relief of pain. They developed pain around groin between one and two years following the surgery. Inflammatory markers were normal. MRI/Ultrasound scanning showed the presence of cystic lesions around the hip. They all presented with relatively late dislocation (26 months to six years). At exploration there was a large joint effusion with necrosis and detachment of the abductors. A characteristic finding was an avascular bare trochanter stripped free of any soft tissues. Histology showed a predominantly histiocytic response in keeping with the findings of Willert and Pandit.

Discussion: In the absence of any obvious causes for dislocation, one should have a high index of suspicion for the possibility of metal hypersensitivity causing joint effusion, muscle necrosis and thereby leading to instability due to the progressive periosteal and soft tissue erosion. These patients should be considered for early revision of the bearing surface to prevent further damage to the muscle and bone. If the abductors are completely detached a more constrained type of bearing should be used to improve the stability. To the best of our knowledge this is the first report of this unusual complication following MoM bearings.

46 Sacral chordoma patients treated between 1987 and 2004 are reviewed. The importance of early diagnosis, adequate surgical margin and post operative radiotherapy for optimum outcome and survival is stressed.

There were 33 male and 13 female patients, with a mean age of 61 years (38–73 years). The surgical approach depended on the level and extent of the lesion, with an anteroposterior approach used in 23 and posterior approach in 17 patients. 20 had partial sacrectomy, 17 had subtotal sacrectomy and 3 underwent total sacrectomy. 6 patients were deemed inoperable and received palliative therapy. 14 patients received radiotherapy post-operatively. The length of average follow up was 4.27 years (range 2–15.7 years).

Low back pain was the most common presenting symptom (80%), and 50% patients had a palpable mass. The mean duration of symptoms prior to diagnosis was 2 years (range 1 month–10 years). Examination revealed a palpable mass in 7 both externally and on rectal examination. 10 had a palpable mass on rectal examination but not externally. 2 patients presented with multiple metastases and another 2 with widespread local disease. Excision was complete in 23 patients and incomplete in 17. Histology revealed dedifferentiation in 4. Complete excision margin was achieved in 69.6% through combined approach and 52.9% through posterior approach only. 24 patients (52%) had local recurrence. Without adjuvant radiotherapy the mean disease free period following complete excision was 3.5 years, compared to 0.9 years following incomplete excision. Adjuvant radiotherapy extended the mean disease free period following incomplete excision to 1.8 years.

The authors conclude that an early diagnosis and careful examination is important. Wide excision remains the mainstay of treatment. If excision is incomplete radiotherapy increases the disease free period although local recurrence is inevitable. The use of a combined approach increases the likelihood of complete excision.

Purpose: To report the importance of early diagnosis, adequate surgical margin and postoperative radiotherapy for optimum outcome and survival.

Study Design: A retrospective review of 46 sacral chordoma patients treated between 1987 and 2004.

Methods: There were 33 male and 13 female patients, with mean age of 61 years (38 to 73 year). The surgical approach depended on the level and extent of the lesion, with an anteroposterior approach used in 23 and posterior approach in 17 patients. 20 had partial sacrectomy, 17 had subtotal sacrectomy and 3 underwent total sacrectomy. 6 patients were deemed inoperable and received palliative therapy. 14 patients received radiotherapy postoperatively. The length of average follow up was 4.27 years (range 2–15.7 years).

Results: Low back pain was the most common presenting symptom (80%), and 50% patients had a palpable mass. The mean duration of symptoms prior to diagnosis was 2 years (range 1 month–10 years). Examination revealed a palpable mass in 7 both externally and on rectal examination. 10 had palpable mass on rectal examination but not externally. 2 patients presented with multiple metastases and another 2 with widespread local disease.

Excision was complete in 23 patients and incomplete in 17. Histology revealed dedifferentiation in 4. Complete excision margin was achieved in 69.6% through combined approach and 52.9% through posterior approach only. 24 patients (52%) had local recurrence. Without adjuvant radiotherapy the mean disease-free period following complete excision was 3.5 years, compared to 0.9 years following incomplete excision. Adjuvant radiotherapy extended the mean disease-free period following incomplete excision to 1.8 years.

Conclusion: An early diagnosis and careful examination is important. Wide excision remains the mainstay of treatment. If excision is incomplete radiotherapy increases the disease free period although local recurrence is inevitable. Use of combined approach increases the likelihood of complete excision.

Introduction: Surgeons in the UK and Europe generally use a thinner cement mantle than their counterparts in the USA for the femoral component in total hip replacement (THR). The aim of this study was to compare the performance of different thicknesses of cement mantle using finite element analysis. The measures by which comparison might be made include cement cracking, subsidence, migration and stress shielding. In this study, we use a linear-elastic model of the implanted femur to give a prediction of the stresses in the cement mantle and in the femoral cortex. These measures give an indication of the relative rates of cement cracking and loss of bone stock due to stress shielding. To assess the reliability of our model in representing patients with different bone densities, we use a range of cancellous bone stiffnesses.

Method: Two cadaveric femora from the same donor were sized, reamed and implanted with identical plastic replica femoral components following standard surgical technique for the Stanmore Hip system. One was prepared using UK rasps, over-reaming by ~2mm, the other using US rasps, over-reaming by ~5mm. Serial CT-scans were used to create three-dimensional geometric models of the implanted femora. Two finite element meshes were hand-built in MSC. Marc finite element software, incorporating cortical and cancellous bone, bone cement and prosthesis. Each model consisted of 10,000 eight-noded brick elements, with a fully bonded stem-cement interface. The thick and thin cement mantles had thicknesses of 2.5mm and 1.0mm respectively, in regions where thickness is affected by rasp size. Models were identical in the distal medullary canal. Cortical bone was modelled as transversely isotropic, with longitudinal and transverse moduli of 17.0 and 11.5 GPa. Bone cement was given a modulus of 2.7 GPa. Loading conditions were chosen to represent the heel-strike phase of gait. In order to assess the impact of variability in patient bone density, cancellous bone modulus was varied between 0.06 and 2.90 GPa.

Results: Equivalent stress was examined on the external surface of the cortex and the internal surface of the cement mantle. The lowest cortical bone stresses were proximal and the highest cement stresses around the distal tip of the prosthesis. In the proximal cortex, higher equivalent stresses were observed medially and laterally with a thick cement mantle. Distally, lower cement stresses were observed in the thick cement mantle. With the highest cancellous modulus, there was little difference between the two models. As this modulus was reduced, stress differences between the models became more apparent. For all cancellous bone moduli, peak distal cement stresses were lower and minimum proximal calcar stresses higher in the thick cement mantle.

Discussion: Proximal stress shielding was greatest in the calcar, in agreement with clinical findings. The thicker cement mantle led to less stress shielding in this region. Cement stresses, highest around the distal tip of the prosthesis, were larger in the thin cement mantle. This suggests a higher rate of both cracking and bone resorption in thin cement mantles. Although observed over a range of cancellous bone stiffness, this finding applies particularly to patients with low bone density.

Introduction: Aseptic loosening remains the commonest causes of failure of total hip arthroplasty. Cement mantle defects are associated with aseptic loosening. This study aimed to determine a correlation between surgical approach and cement mantle defects in the Stanmore Hip. The Stanmore total hip replacement was chosen because it has greater than an eighty-five percent survivorship over 25 years and unlike other prostheses with comparable results such as the Charnley total hip, it remains essentially unchanged to date.

Method: This was a retrospective review of all Stanmore hips. AP and lateral radiographs were available for 62 patients operated via the posterior approach and 100 patients operated via the anterolateral approach. The mean cement thickness in all fourteen Gruen zones was estimated for each patient. Gruen zones IV and XI, representing the stem tip, were removed from data relating to mantle thickness. Mantles were graded as less than 2mm, 2–5mm, 5–10mm and more than 10mm. Alignment was also measured.

Results: Fifty-nine percent (32/54) of cement mantle defects are seen in Gruen zones VIII to XIV. The mean cement mantle thickness in A-L approach was 3.11mm compared to 4.23mm with the posterior approach. This corresponds with the frequency of cement mantle defects occurrence. No cement defects were seen in Gruen zones IV or XI. Using the anterolateral approach, defects were observed in 49 out of 1200 zones (4.08%) and using the posterior approach in 6 out of 744 zones (0.81%). With the anterolateral approach, 19 out of 100 cement mantles (19%) had defects, compared to only 3 out of 62 (4.84%) with the posterior approach. Defects were most commonly seen in zones I, V, VIII and XII, which corresponds to valgus and posterior orientation of the stem.

Discussion: The posterior approach does generate a more uniform cement mantle. Several studies suggest that a cement mantle smaller than 2mm or greater than 10mm can be detrimental to the survivorship of the arthroplasty. This study suggests that a deficient cement mantle is more likely using an anterolateral approach.

Increasingly hospitals are moving away from hard copy xrays to digital films. These offer advantages in terms of cost, film availability and decreased radiation dosage but concerns have been raised about the accuracy of these images for preoperative templating.

We reviewed the pre and post operative films in 20 patients with subcapital fractured necks of femur. Each film was reviewed by 3 different observers on 3 separate occasions. The sizes of the femoral head and the hemi-arthroplasty were measured using the PACS digital system. These were then compared with the known size of the implant.

A total of 360 measurements were taken. Intra and inter observer errors were low with intra class correlations of in excess of 0.98 and 0.99 respectively. The average magnification on the pre-op film was 117.6% (t=18.96, p< 0.0001) and on the post-op film 121.5% (t=22.18, p< 0.0001) with a range of 109.3% to 128.2%. The overall magnification was 119.6%.

We conclude that measurements made on PACS have a high repeatability and reproducibility but that PACS has a significant and wide variation in magnification errors. PACS should therefore not be used for templating until a way of standardising magnification has been found.

Introduction: Surgeons in the UK and Europe generally use a thinner cement mantle than their counterparts in the USA for the femoral component in total hip replacement. The aim of this study was to compare the performance of different thicknesses of cement mantle using finite element analysis. A linear-elastic model of the implanted femur is used to give a prediction of the stresses in the cement mantle and in the femoral cortex. These measures give an indication of cement cracking rates and stress shielding. To assess the reliability of our model in representing patients with different bone densities, we use a range of cancellous bone stiffnesses.

Method: Two cadaveric femora from the same donor were sized, reamed and implanted with identical Stanmore Hips. One was prepared using UK rasps, over-reaming by 2mm, the other using US rasps, over-reaming by 5mm. Serial CT-scans were used to create three-dimensional geometric models of the implanted femora. Two finite element meshes were hand-built in MSC.Marc finite element software, incorporating cortical and cancellous bone, bone cement and prosthesis, with a bonded stem-cement interface. Loading conditions were chosen to represent the heel-strike phase of gait. In order to assess the impact of variability in patient bone density, cancellous bone modulus was varied between 0.06 and 2.90 GPa.

Results: Equivalent stress was examined on the external surface of the cortex and the internal surface of the cement mantle. The lowest cortical bone stresses were proximal and the highest cement stresses around the distal tip of the prosthesis. In the proximal cortex, higher equivalent stresses were observed medially and laterally with a thick cement mantle. Distally, lower cement stresses were observed in the thick cement mantle. With the highest cancellous modulus, there was little difference between the two models. As this modulus was reduced, stress differences between the models became more apparent.

Discussion: Proximal stress shielding was greatest in the calcar, in agreement with clinical findings. The thicker cement mantle led to less stress shielding in this region. Cement stresses, highest around the distal tip of the prosthesis, were larger in the thin cement mantle. This suggests a higher rate of both cracking and bone resorption with thin cement mantles, particularly in patients with low bone density.

The purpose of this study is to demonstrate that definitive surgery (extraperiosteal excision) is required in patients with osteofibrous dysplasia (OFD) due to the risk of recurrence and co-existent adamantinoma

OFD is an unusual childhood condition, which almost exclusively affects the tibia. It is thought to follow a slowly progressive course and to stabilise after skeletal maturity. The possible link with adamantinoma is controversial with some authors believing that they are part of one histological process. This therefore provides difficulty in recommending treatment options

A retrospective review of OFD was conducted. Using the Stanmore Bone Tumour Unit database 22 cases were identified who were initially diagnosed with OFD or were diagnosed on final histology. All cases were tibial except one lesion in the ulna and one in the fibula

Management was diverse depending on the severity of symptoms and the extent of the lesions encountered. Definitive (extraperiosteal) surgery in the majority of our patients was localized excision for small lesions (less than 50% of the bony circumference) and segmental excision followed by reconstructive surgery for more extensive ones. Seven patients had a sharkbite excision and a further seven were treated with fibula autografting. Of the latter group, one required further excision and bone transport due to recurrence of OFD. An additional five underwent bone transport & distraction osteogenesis using the Ilizarov technique and one had a proximal tibial replacement. Nine initially underwent curettage, but eight recurred (recurrence rate 88.9%). No recurrences occurred following localized extraperiosteal excisions and bone transport. There were three confirmed cases of adamantinoma.

In view of the risk of association of OFD with adamantinoma, and to some extent the continuous morbidity of OFD if left untreated, we believe that radical extraperiosteal excision is indicated in most if not all cases of OFD

Introduction: The purpose of this study is to demonstrate that definitive surgery (extraperiosteal excision) is required in patients with osteofibrous dysplasia (OFD) due to the risk of recurrence and co-existent adamantinoma. The possible link with adamantinoma is controversial with some authors believing that they are part of one histological process. This therefore provides difficulty in recommending treatment options.

Methods: Using our database 22 cases of OFD were identified. Management was diverse.

Results: Definitive (extraperiosteal) surgery, in the majority of our patients, was localized excision for small lesions (less than 50% of the bony circumference) and segmental excision followed by reconstructive surgery for more extensive ones. Seven patients had a “shark-bite” excision and a further seven were treated with fibula autografting. Of the latter group, one required further excision and bone transport due to recurrence of OFD. Five underwent bone transport & distraction osteogenesis and one had a proximal tibial replacement. Nine initially underwent curettage, but eight recurred. No recurrences occurred following localized extraperiosteal excisions and bone transport. There were three confirmed cases of adamantinoma.

Discussion: In view of the risk of association of OFD with adamantinoma, and to some extent the continuous morbidity of OFD if left untreated, we believe that radical extraperiosteal excision is indicated in most if not all cases of OFD.

Introduction and Aim: The purpose of this study is to demonstrate that definitive surgery (extraperiosteal excision) is required in patients with osteofibrous dysplasia (OFD) due to the risk of recurrence and co-existent adamantinoma. OFD is an unusual childhood condition, which almost exclusively affects the tibia. It is thought to follow a slowly progressive course and to stabilise after skeletal maturity. The possible link with adamantinoma is controversial, with some authors believing that they are part of one histological process. This therefore provides difficulty in recommending treatment options.

Method and Results: A retrospective review of OFD was conducted. Using the Stanmore Bone Tumor Unit database, 22 cases were identified who were initially diagnosed with OFD or were diagnosed on final histology. All cases were tibial except one lesion in the ulna and one in the fibula. Management was diverse, depending on the severity of symptoms and the extent of the lesions encountered. Definitive (extraperiosteal) surgery in the majority of our patients was localised excision for small lesions (less than 50% of the bony circumference) and segmental excision followed by reconstructive surgery for more extensive ones. Seven patients had a ‘sharkbite’ excision and a further seven were treated with fibula autografting. Of the latter group, one required further excision and bone transport due to recurrence of OFD. An additional five underwent bone transport and distraction osteogenesis using the Ilizarov technique and one had a proximal tibial replacement. Nine initially underwent curettage, but eight recurred (recurrence rate 88.9%). No recurrences occurred following localised extraperiosteal excisions and bone transport. There were three confirmed cases of adamantinoma

Conclusion: In view of the risk of association of OFD with adamantinoma, and to some extent the continuous morbidity of OFD if left untreated, we believe that radical extraperiosteal excision is indicated in most if not all cases of OFD

Aim: Sacral tumours are rare and can form a wide variety of differential diagnoses. We present a series of sacral tumour patients treated at a regional tumour centre; describing our experience of their management. Method: A retrospective study reviewing 76 sacral tumour patients, presenting to the Royal National Orthopaedic Hospital, Stanmore, from April 1976 to April 2002. The minimum follow-up period was 6 months. For each tumour type we looked at the incidence, diagnosis and outcome. Results: 69 of the lesions were primary bone tumours, 3 metastatic and 4 haematopoietic tumours. 33% of all tumours were chordomas. Osteosarcoma (10%), chondrosarcoma (8%) and giant cell tumour (8%) were the next most common. The commonest presenting symptom was lower back pain (64 cases). Good survival was demonstrated with chordomas and giant cell tumours. Osteosarcomas and chondrosarcomas had poor survival. Tissue diagnosis was accurately achieved with image-guided needle biopsy (61 cases). Magnetic resonance imaging (MRI) and computed tomography (CT) provided sufficient details for preoperative planning. Conclusion: The symptoms and signs of sacral tumours are non-specific and may lead to a misdiagnosis of degenerative disease of the spine. In our series chordomas account for only a third of all sacral tumours. Early diagnosis and staging are essential in order to determine definitive management and infl uence outcome. Surgery remains the most effective method for treating the malignant tumours.

Aim: Chordomas are relatively rare, malignant and strictly found in the midline. This study is to review our experience in the diagnosis, treatment and outcome of sacral chordomas. Method: A retrospective study reviewing 25 sacral chordoma patients treated at the Royal National Orthopaedic Hospital between August 1987 and April 2002, with a minimum follow-up of 6 months. Results: Of the 25 patients, 17 were male and 8 were female. The mean age at diagnosis was 61 years, and the mean duration of symptoms was 2 years. The commonest presenting symptom was lower back pain (20 cases). Three patients had inoperable tumours at the time of referral; the remaining 22 underwent surgical excision. A complete excision (based on microscopic examination) was achieved in11 cases, 2 of whom received adjuvant radiotherapy. Of the11 who had an incomplete excision 8 received adjuvant radiotherapy. Complete excision extended the mean disease free period to2.92 years, compared to 0.67 years following incomplete excision. The disease free period following an incomplete excision was extended from a mean of 0.67 years to 2.82 years with radiotherapy. 10 patients had postoperative neurological complications. Conclusion: We believe that the aim of surgical resection should be a microscopically complete excision margin, having documented an increased time to recurrence in patients in whom this has been achieved, compared to those treated with an incomplete excision. Radiation therapy should be given after an incomplete excision as we have shown that it lengthens the disease free interval in these cases.

Aims: Damage to articular hyaline cartilage may predispose to earlyonset osteoarthritis. Hyaline cartilage has not been shown to spontaneously regenerate and previous methods of stimulating repair have often yielded þbrocartilage. Autologous chondrocyte implantation (ACI) offers the potential for hyaline cartilage repair. Methods: A prospective study of 31 patients undergoing ACI using the chondrogide membrane. Patients were assessed clinically using validated knee scores pre-operatively and post-operatively at yearly intervals. Arthroscopy was carried out at one year post implantation and a biopsy of the transplanted area was sent for histological examination. Results: 32 knees (including 2 bilateral) were reviewed clinically at one year, and 15 were reviewed at 2 years. 33 defects (including 2 defects in one knee) were assessed arthroscopically at one year. Only one repair showed hypertrophy at one-year arthroscopy, and 8 had poor integration. Hyaline-like cartilage was demonstrated in 70% of the repairs. Patients showed improvement in the Verbal Numerical Pain scores and in the Lysholm and Gillquist score. Conclusions: In our series, the use of chondrogide membrane shows a low incidence of hypertrophy when compared to periosteum. Improvement in knee scores was statistically signiþcant at one and two years.

The use of foot pumps and graduated compression stockings have been shown in combination to reduce the incidence of thromboembolic disease after total hip arthroplasty. What has not been described is if there combined use is synergistic as all clinical trials use them in combination.

We examined the effect that wearing compression stockings had on the ability of foot pumps to accelerate peak venous velocities in the common femoral vein (CFV) of ten healthy volunteers. We measured this effect by duplex scanning the CFV under four conditions: foot pump on or off and stockings on or off.

The combination of foot pumps on without stockings led to the greatest increase in peak venous velocity. This represented a 34% increase in efficiency compared to not wearing stockings.

It is not known if this difference could account for a reduction in thromboembolic episodes, this could only be answered with a randomised clinical trial.

Introduction: The viscosity of bone cement used in total joint arthroplasty is an important for determining the proper handling characteristics of the cement and its interlock with bone. The degree of penetration and, therefore, the integrity of the arthroplasty are dependent on the viscosity of the bone cement system. As yet there is still no standard measurement of the efficacy of each bone/cement system with regard to the ability of the cement to penetrate the interstices of the bone.

Aim: To quantify the rheological properties of bone cement systems with the view to assisting in cement selection for orthopaedic purposes

Material & Methods: The rheological properties of a variety of current bone cements were determined using a novel apparatus developed at the CSIRO called the Micro Fourier Rheometer (MFR). This device measures the complex viscosity and complex modulus by subjecting a sample to small amplitude oscillatory squeezing between two parallel plates. The force transmitted through the sample is detected by a dynamic load cell and the complete signal spectrum is then analysed using Fourier Techniques. The bone cement is mixed according to manufacturers’ instructions and placed between the plates and is then subjected to a random displacement. Subsequent Fourier analysis lends itself to rheological parameters such as real and imaginary modulus, viscosity and phase (1–100 Hz).

Results: Consistent with earlier studies, it was found that the viscosity increased with time in an almost linear manner due to the progression of the polymerisation reaction of the cement. Thereupon the cement mass began its exothermic phase and the viscosity increased exponentially until fully set. The complex modulus at this time, when extrapolated to zero frequency, corresponded to the static modulus (as in conventional mechanical testing). The viscosity was highly dependent upon the shear rate (or frequency). As the cement was sheared the viscosity reduced, establishing the pseudo-plastic or shear-thinning nature of these materials. The phase provided an accurate measure of the setting and working time of the cement brands corresponding with studies by Krause (1982) and Ferracane (1981).

Conclusions: The results supported the conclusion that rapid insertion of the prosthesis is recommended, creating high shear stresses, thus decreasing the cement’s viscosity and allowing better cement penetration and mechanical interlock. The study highlights the differences between the major brands of bone cement.