In recent years, machine learning (ML) and artificial neural networks (ANNs), a particular subset of ML, have been adopted by various areas of healthcare. A number of diagnostic and prognostic algorithms have been designed and implemented across a range of orthopaedic sub-specialties to date, with many positive results. However, the methodology of many of these studies is flawed, and few compare the use of ML with the current approach in clinical practice. Spinal surgery has advanced rapidly over the past three decades, particularly in the areas of implant technology, advanced surgical techniques, biologics, and enhanced recovery protocols. It is therefore regarded an innovative field. Inevitably, spinal surgeons will wish to incorporate ML into their practice should models prove effective in diagnostic or prognostic terms. The purpose of this article is to review published studies that describe the application of neural networks to spinal surgery and which actively compare ANN models to contemporary clinical standards allowing evaluation of their efficacy, accuracy, and relatability. It also explores some of the limitations of the technology, which act to constrain the widespread adoption of neural networks for diagnostic and prognostic use in spinal care. Finally, it describes the necessary considerations should institutions wish to incorporate ANNs into their practices. In doing so, the aim of this review is to provide a practical approach for spinal surgeons to understand the relevant aspects of neural networks.

Cite this article: Bone Joint J 2021;103-B(9):1442–1448.

The widespread dissemination of high-quality research facilitates keeping up to date with evidence-based practice, but the vast quantity can be overwhelming to physicians and surgeons. Information graphics, abbreviated to infographics, convey information using visualisations and images in an engaging manner. This format of presenting research format is preferable to 80% of clinicians when compared to text articles, and the long-term retention of information has been shown to be improve by a factor of 6.5 when methods were compared. Journal club was audited in our institution over 3 months. A multi-choice questionnaire was constructed weekly so as to test the attendees' recall of the research presented on a weekly basis. After five weeks, infographics were introduced, and the attendees' recall was assessed again on a weekly basis at the end of each journal club. The introduction of infographics to journal club saw improved test results from the journal club attendees. Not only was information retention improved, but the duration of journal club reduced following the intervention. Research can be disseminated efficiently using infographics in place of conventional journal club presentations. Satisfaction rates among clinicians, both with information retention and journal club duration, demonstrate the benefit of their use in teaching hospitals.

Background

The internet has revolutionized the way we live our lives. Over 60% of people nationally now have access to the internet. Healthcare is not immune to this phenomenon. We aimed to assess level of access to the internet within our practice population and gauge the level of internet use by these patients and ascertain what characteristics define these individuals.

Treatment of segmental bone loss remains a major challenge in orthopaedic surgery. This study evaluated the healing potential of a series of highly porous tissue engineering scaffolds with the current clinical gold standard. We compare healing of collagen-glycosaminoglycan (CG) and collagen micro-hydroxyapatite (CHA) scaffolds, with and without recombinant bone morphogenetic protein-2 (BMP2), with autogenous bone graft (ABG) in the healing of a 15mm rabbit radius defect, which were filled with either CG scaffold, CHA scaffold, CG-BMP2, CHA-BMP2 or ABG. Serial radiographs and micro-computed tomography (µCT) at six week radiographs demonstrated complete defect bridging with callus using CHA and CG-BMP2 while the CHA-BMP2 was already in an advanced state of healing with cortical remodeling. By sixteen weeks CHA, CG-BMP2 and ABG all had advanced healing with cortical remodeling while CHA-BMP2 had complete anatomic healing. Quantitative histomorphometry values demonstrated similarly high healing levels of healing in CHA, CG-BMP2 and ABG with highest overall values in the CHA-BMP2 group. Thus, treatment of a critical sized, weight bearing, rabbit radius defect with a CHA scaffold can result in full cortical bridging with medullary cavity development. In addition, a CHA-BMP2 combination can result in fully mature, anatomic healing. The use of an off-the-shelf CHA scaffold for direct surgical placement into a defect site may be an effective bone graft substitute in the treatment of skeletal defects. The ease of manufacture, storage and peri-operative preparation may offer an alternative to traditional strategies, as well as to more recent BMP2 devices. This study provides clear evidence that CHA scaffolds can perform as well as autogenous bone grafts and supports their use as a viable alternative. Where the use of BMP2 may be desirable, these materials provide an ideal delivery mechanism and using a very low (near physiological) dose, healing superior to autogenous graft may be achieved.

Introduction: Definitions of surgical site infections are based on those of CDC, published in 1992. Infections that occur within 30 days of surgery are classified as:

Superficial – involves only the skin or subcutaneous tissue.

Between 2006 and 2008 the infection rates of the National Spinal Surgery Unit have been closely monitored as part of a multidisciplinary team approach led in large part by the Infection Control Team. A surveillance protocol was developed. They prospectively monitored every spinal surgery patient as part of a infection control data base. Biographical and medical history data were collated including diabetic status, prophylactic antibiotic use and surgical procedure. Information was collated and feedback on changes was examined by audit which was conducted regularly.

Methods: As part of the routine audit of the NSSU department a deep infection rate of 3.5% was noted in 2006. The infection control team set up a specific unit to co ordinate surveillance of NSSU. We describe simple and evidence based protocols for prophylactic antibiotic use in conjunction with the Pharmacy, Infection Control and Microbiology department was organised in running with international standards. Furthermore, surgical, nursing and paramedical staff, involved in the NSSU, were swabbed routinely. New rigid guidelines were introduced in theatre for draping patients including the addition of topical alcohol use and 8 minute minimum bethidine drying time.

Results: From 2006, deep infection rate was 3.5%. This was followed by a 2.49% in 2007 and 1.79% in 2008. Of note the deep infection rate in 2004 was 5.5% (2 years prior to implementation of Infection Control protocols).

Conclusions: The National Spinal Surgery Unit was able to decrease the deep infection rate by 51% over 3 years by the implementation of careful prospective surveillance by a multidisciplinary team involving an Infection Control team which monitored the NSSU prospectively as well as co-ordinating changes in the protocol of antibiotic use as well peri-operative sterile techniques. We describe simple protocols which can be easily used in other institutions to aid in the mitigation of deep spinal surgical infection.

Horse riding is a popular competitive sport and leisure pursuit worldwide. Previous research has highlighted the unpredictable and independent nature of horses and high injury risk inherent in travelling at speeds of up to 65kph, 3-metres above the ground on an animal weighing between 450–500kg. In Ireland, jockeys register with the Turf Club as either professional or amateur with the remaining riders participating as unregistered.

The aim of this study is to determine the national incidence of acute spinal cord injury (ASCI) and vertebral body injury (VBI) in horse riding in the Republic of Ireland, and to compare and contrast injury characteristics in registered and unregistered riders over an 11-year period (1995–2005).

Chart review and structured telephone interview was performed in all cases to determine mechanism of injury, discipline, protective equipment, immediate management and whether the rider considered the injury could be prevented. American Spinal Injuries Association (ASIA) impairment score was used to classify outcome. Data for injuries sustained in competitive racing, for both registered and unregistered riders, was correlated with Irish Turf Club race records to ensure accuracy.

Results: Sixteen cases of ASCI and 46 of VBI were identified over the study period (Table 1). Over the study period, there was a mean annual incidence of 1.5 (1 to 4) ASCI and 4 VBI (0 to 7). Cervical injuries were significantly more likely to result in ASCI (n=14 (52%), p=0.004) than either thoracic or lumbar injuries. Riders who had an ASCI spent more days in hospital (p=0.007); were less likely to have had a previous riding injury (p= 0.046); and following injury, less likely to return to horse riding at any level (p= 0.033). Seven ASCI (44%) and ten VBI (22%) patients were managed operatively. Three ASCI (19%) and 4 VBI (9%) occurred in registered riders. A fall in flight jumping was the commonest injury pattern (32%) overall, with 60% of ASCI and 26% of VBI by this mechanism occurring in registered riders. Overall, only 19% of riders report wearing a back protector at the time of injury. Of these, 30% sustained cervical injury, 17% thoracic injury and 0% lumbar injury. For ASCI riders, final ASIA impairment classification was A= 4, B= 2, D= 4 and E= 5.

Conclusion: Equestrian sports, both for registered and unregistered riders pose substantial risk. Despite greater compliance with wearing of protective equipment, registered riders are at increased risk of sustaining ASCI than unregistered risers. Morbidity is significant following ASCI, with ten riders permanently disabled as a direct result of participation.

Introduction: The Sheehan total knee endoprosthesis has been widely used since 1971. It incorporates a semi-constrained hinge with intramedullary stems cemented into the femur and tibia for fixation. This gives a stable polycentric knee mechanism that allows axial rotation as well as simulating other knee movements. This design has certain disadvantages including the large amount of bone resected for implantation and its constrained nature which predisposes to loosening. Revision rate of up to 30% have been reported. We discuss the difficulties encountered during revision and the techniques that need to be used to overcome these.

Patients and methods: We reviewed the records of 21 patients who required revision of Sheehan TKRs between 1987 and 2001. Reason for revision was recorded and all patients were scored using the Knee Society Index of Severity Instrument (Saleh et al CORR 2001). The operative details were examined and technical difficulties at the time of surgery recorded. Per-operative and early post-operative complications related to the revision procedure were also noted.

Results: The average age of patients requiring revision was 65 years old (range 39–79). The average time from primary surgery to revision was 16.2 years (range 8–20 years). The reasons for primary surgery were rheumatoid arthritis in 9 and osteoarthritis in 12. Revision surgery was required for pain associated with tibial subsidence and painful bone on bone contact in 14.Two patients had dislocation of their tibial on femoral component. One patient had a one-stage revision for infection and one had revision for a fractures tibial intramedullary stem. Three patients had revision to anterior flanged femoral components to facilitate patellar resurfacing for patello-femoral pain. The overall complication rate approached 80%!

Discussion: While the Sheehan TKR was of great benefit to a large number of patients it is not without its problems. These results show that prostheses coming to revision did not necessarily fail early and so with time we can expect more to present for revision. The high complication rate and the need for complex reconstructive techniques attest to the difficulty of revising these prostheses. Some of these problems are the legacy of the prosthetic design and should be borne in mind when taking on these cases.

Study design: Retrospective review of patients with cervical spondylosis treated with three-level anterior cervical discectomy and fusion with plate fixation.

Objective: To assess the radiographic and clinical outcome of three-level instrumented anterior cervical discectomy.

Summary of Background data: Three-level cervical discectomy without plate fixation has shown high rates of pseudarthrosis and poor outcomes. The addition of internal fixation may improve these parameters.

Methods: 46 patients were observed for an average of 17.6 months (range, 6–51). All had three level anterior cervical discectomy and fusion with tricortical iliac crest autograft (4 cases), fibular ring allograft (38 cases), or titanium cage (four cases). Allografts and cages were filled with iliac crest autograft. All patients had semi-rigid plating. Clinical and radiographic follow-up data were obtained. Clinical outcomes were measured as described by Robinson and with the Nurick scale.

Results: Forty-four patients achieved solid fusion. Two patients had additional surgery for junctional disease, and in one of them pseudarthrosis repair was also performed. One asymptomatic pseudarthrosis was noted. With a successful result defined as an excellent or good outcome accompanied by significant pain relief, 38 patients had a successful result (83%). Radiographic adjacent level disease was diagnosed in 11 patients postoperatively and was symptomatic in 5.

Conclusion: Three-level anterior cervical discectomy with plate fixation has a high rate of fusion, a low complication rate, and acceptable outcome in the treatment of multilevel cervical spondylosis.

Introduction: Articular fractures, especially in weight-bearing joints of the lower extremity, require anatomical reduction for good long-term function. If anatomic reduction is achieved 90% of patients have good results. Accurate anatomical reduction of acetabular fractures is made difficult y the complicated anatomy of the acetabulum and pelvis. Plain films and computerised tomography are very useful in the assessment, classification and planning for surgery of these fractures, but conventional imaging only provides two dimensional images of these fractures. While interpretation of traditional imaging techniques becomes better with experience novel techniques may assist in the understanding of these complex injuries. This project presents the use of three dimensional life size models which can be rapidly manufactured from CT scans to facilitate fracture classification and operative planning.

Patients and Methods: Standard 4 mm CT cuts were reformatted to 2 mm and saved as DICOM files for a series of 15 consecutive patients with complex acetabular fractures (not including isolated posterior wall injuries). These were imported into Mimic (Materialise) data conditioning software, which allowed manipulation and thresholding of images so that a three-dimensional computer model could be built. The data was exported to the Selective Laser Sintering (SLS) system and a life size three-dimensional model constructed. Three consultant orthopaedic surgeons and three senior trainees were asked to classify, using the system of Letournel, each fracture using 1) conventional radiographs (AP pelvis, Judet views and CT scans). 2) Using a model. As no absolute of fracture type was available the Kappa statistic was used to evaluate inter and intraobserver agreement. This compared an observed level of agreement with the level of agreement that would be expected by chance alone.

Results: Interobserver agreement was not absolute using either conventional radiographs or the sintered model. For the consultants the kappa statistic using conventional radiographs was 0.61 while the kappa value using the model was 0.76 (p=< 0.05). For the trainees the kappa was 0.42, using conventional radiographs and 0.71 using the model (p=< 0.01)>

Discussion: The complex three-dimensional anatomy of the pelvis and acetabulum make assessment and classification of fractures of these structures notoriously difficult. The value of accurate fracture classification is well recognised particularly in the treatment of intra-articular injuries. The use of this real life model of a fractured pelvis has been shown in this study to significantly reduce the degree of interobserver variability in the classification of these injuries. This effect is particularly evident for less experienced surgeons.

Conclusion: The technique is available and relatively inexpensive. These models may be of great benefit for preoperative planning, classification and assessment of prognosis in acetabular fractures. Its use should prove invaluable as a tool to aid clinical practice.

Introduction: The Ganz periacetabular osteotomy aims to improve femoral head coverage in dysplastic hips. It is joint preserving procedure and therefore is ideally preformed before significant articular cartilage degeneration. One proposed advantage of this procedure is that it partially preserves the posterior column and does not disrupt the vascular supply of the main fragment. This study aims to 1) assess the role of MR imaging in the perioperative evaluation of articular cartilage and labrial tissues prior to Ganz osteotomies and 2) to document any alteration in the vascularity of the acetabular fragment post operatively.

Patient and Methods: Twenty patients (all female, average age 18.2 years) under consideration for peracetabular osteotomy for hip dysplasia and MR Studies of the pelvis as part of the perioperative assessment. Sixteen patients had follow-up imaging at 4, 12 and 26 weeks post surgery, at which time evidence of healing, oedema, vascularity and femoral head coverage were assessed.

Discussion: MR imaging has proven to be a reliable method of assessing articular cartilage health before considering pelvic osteotomy. Hopefully this will allow more appropriate selection of patients likely to benefit from this procedure. In addition MRI scanning allows clearer assessment of other articular elements, such as labium and ligamentum teres, that are difficult to visualize with plain radiographs and CT scans. A further benefit of MR scanning is that, as this study has shown the vast majority of patients who are potential candidates are female of childbearing age and it voids the use of ionizing radiation in this sensitive group of patients. This study has shown that despite some early alterations in osteotomy fragment vascularity the ultimate outcome is that vascularity is substantively unharmed by periacetabular osteotomy.

Conclusion: MR imaging is extremely useful in the perioperative workup and postoperative follow-up in patients undergoing Ganz periacetabular osteotomies.

Introduction: The Sheehan total knee endoprosthesis has been widely used since 1971. It incorporates a semi-constrained hinge with intramedullary stems cemented into the femur and tibia for fixation. This gives a stable polycentric knee mechanism that allows axial rotation as well as stimulating other knee movements. This design has certain disadvantages including the large amount of bone resected for implantation and its constrained nature, which predisposes to loosening. While clinically excellent results have been reported in 95% of patient by some authors, other papers have reported much lower rates of successful outcome and revision rates of up to 30%. Few papers however report the difficulties encountered during revision or the techniques that need to be used to overcome these.

Patients and Methods: We reviewed the records of 21 patients who required revision of Sheehan TKR’s between 1987 and 2001. Reason for revision was recorded and all patients were scored using the Knee Society Index and Severity Instrument (Saleh et al CORR 2001). The operative details were examined and technical difficulties at the time of surgery recorded. Per-operative and early post-operative complications related to the revision procedure were also noted.

Results: The average age of patients requiring revision was 65 years old (range 39–79). The average time from primary surgery to revision was 16.2 years (range 8–20 years). The reasons for primary surgery were rheumatoid arthritis in 9 and osteoarthritis in 12. Revision surgery was required for pain associated with tibial subsidence and painful bone contact in 14. Five of these also had varus/valgus instability in excess on 30°. Two patients had dislocation of their tibial on femoral component. One patient had a one-stage revision for infection and one had revision for a fractures tibial intramedullary stem. Three patients had revision to anterior flanged femoral components to facilitate patellar resurfacing for patello-femoral pain. In 14 patients the knee was revised to a second Sheehan prosthesis as the degree of bone loss was insufficient to allow cement removal and bone stock reconstruction. Three patients were revised to stemmed Co-ordinate (DepuyTM) revision prostheses, one to a standard AMK surface replacing prosthesis and one to a hinged Finn prosthesis due to global instability. Seven patients required impaction bone grafting and required structural grafting for severe bone loss. The overall complication rate approached 80%! Two patients had wound breakdown, one required grafting. Five patients had persistent wound ooze successfully treated with antibiotics alone. To patients had cortical perforation, which was bypassed by the prosthetic stem, two suffered post-operative fractures, one requiring ORIF, one bracing. Four patient required re-revision, two to kinemax prostheses and two to further Sheehan prostheses.

Discussion: While the Sheehan TKR was of great benefit to a large number of patients it is not without its problems. These results show that prostheses coming to revision did not necessarily fail early and so with time we can expect more to present for revision. The high complication rate and the need for complex reconstructive techniques attest to the difficulty of revising these prostheses. Some of these problems are the legacy of the prosthetic design and should be borne in mind when taking on these cases.

Background The non-motorised microscooter has become the urban transport of choice for children in Ireland. Recently, Josefson highlighted the rising trend of scooter-related injury in the US and predicted possible significant impacts in human and socioeconomic terms.

Materials and Methods. A prospective study was undertaken of all referrals with scooter injuries to accident and emergency departments and fracture clinics in the first three months of the year. These cases were then reviewed at 6 months post injury

Results: There were 151 microscooter injuries seen in the first 3 months of the year, Forming over 4% of all trauma seen over this period. Eighty nine of the patients (59%) were female, and the mean age at presentation was 8.5 years (range 3–15 years). The peak referral rates for January, February and March measured 48%, 29% and 23% respectively. A survey of attending paediatric outpatients over this period revealed that 75% of households possessed at least 1 scooter, and in those households with children aged between 4 and 14 years, the rate of micoscooter possession increased to 83%. Eighty four children suffered fractures and dislocations, 59 suffered soft tissue injuries, 8 had isolated head injuries. Upper limb fractures and dislocations were the most common injury (75 of 84 bone and joint injuries). Fracture of distal third of radius and ulna, was the most common single injury. upper limb fractures wer seen frequently. A high proportion of these had apex dorsal angulation with or without displacement (Smith deformity). Lower limb fractures were relatively rare. The pattern of soft tissue injuries and lacerations mostly affected the head and neck 25 (17%), the lower limb was involved in 19 (13%) and upper limb in 15 (10%) of patients. No major head injuries occurred. Only 5 patients had any adult supervision at the time of their injury. No children wore any formal protective clothing or apparatus. In the 84 patients who had suffered bony injury, at 6 months, 110 patients (73%) had

Introduction: Elucidation of the exact cause of adolescent idiopathic scoliosis (AIS) remains an elusive goal. The intervertebral disc is one of the many areas that have been investigated in an effort to find a cause for this condition. We hypothesize that a qualitative change in the orientation of collagen fibers in the annular layers of the disc could cause the deformity seen in AIS. This paper presents a mathematical model of such a change and how it could produce appropriate deforming forces. Hypothesis: In the normal disc the collagen fibers are obliquely orientated. Fibers in adjacent lamellae are orientated in opposing directions. This means that as forces are transmitted from a compressed nucleus to the annular fibers there is no net force tending to rotate one vertebra with respect to its neighbour. If there is a preponderance of fibers running in one direction as the nucleus is compressed there will be a net resultant force perpendicular to the long axis of the spine tending to produce an intervertebral rotation. This intervertebral rotation, applied to successive spinal segments will cause a scoliotic deformity.

Model: The highly oriented structure of the AF suggests the utility of an explicit representation of the collagen fibres and their mechanical contribution to disc function. In our study we have considered two groups of fibres, representing the clockwise and counter clockwise fibres in the disc. The AF is considered as a continuum containing two populations of fibres assumes to be of equal density and uniform distribution within an isotropic material as originally described by Spencer. Nuclear compression as a result of growth was modelled as a tendency to produce increased intervertebral separation of spinal segments and examined whether the resultant transformation that leads to a scoliotic pattern of deformity. Based on anatomical data from literature the positions of the 12 nodes that represent the thoracic vertebrae are applied to the model. The three-dimensional location of each vertebral body is defined. We store the coordinates of thoracic vertebrae in a three-dimensional matrix. In the present study in order to involve the translation operation in our transformation, we have used the homogeneous transformation matrix or Denavit & Hartenberg matrix.

In the present model for the initial set of transformations the reference axis is chosen to be the lowest vertebral axis (T-12) and remains unchanged throughout the transformation. All elements of the spine above the reference axis are transformed (translated and rotated). After completion of this iteration and storing the values for the origin coordinate and vector values in the next level of the matrix, the next reference axis is chosen. For the second axis everything above the axis will be transformed in the same way with the current axis and the one preceding it remaining unchanged. Therefore for each transformation a new reference axis is taken and the transformations are applied to all vectors and origins above it leaving all elements preceding it unchanged by the transformation.

Results: The first part of the model shows that rotational displacement increases linearly with changes in the fibre ratio. Rotational displacement on the other hand occurs independently of distraction of the vertebral bodies. When the rotational displacement is applied to a series of segments it produces alterations of curvature in the three planes. Specifically it produces a lateral curvature in the coronal plane and a hypokyphotic curvature in the saggital plane. The magnitude of these displacements varies with the imbalance in fibre ratio. Discussion: The proposed changes in annular fiber orientation have been modeled using accepted mathematical methods. These changes will produce an intervertebral rotation whose magnitude depends on the degree of fiber imbalance akin to that seen in AIS. When the displacements produced by this rotation being applied to a series of segments is modeled, it will produce a three dimensional deformity similar to that seen in AIS. Ongoing histological studies are being performed to see if the proposed imbalance can be identified in patients with AIS. Such a fiber orientation anomaly may be genetically determined by some fashion of directional sense gene and may be the aetiological basis for AIS.

Introduction: The need to meet the demands for a hip replacement that will allow young patients to maintain a high activity level with the expectation of enhanced longevity has been the Holy Grail of modern orthopaedic practice for some time. Novel bearing surfaces and methods of component fixation have not as yet managed to sate this need. The Birmingham Hip Resurfacing (BHR) offers a number of theoretical advantages for this demanding patient group. The metal on metal bearing couple facilitates fluid film lubrication and thus minimises wear and reduces osteolysis. The large head size enhances stability minimising the risk of dislocation during strenuous activity. Resurfacing anatomically restores hip geometry facilitating normal hip biomechanics. Finally, in the event of failure preservation of bone stock makes revision surgery less challenging.

In the absence of long-term outcome studies for the BHR these advantages remain theoretical. Furthermore, reports of good short and medium term results require corroboration at independent centres. This paper presents early results in a large series of patients in such an independent unit.

Patients and Methods: Between March 1999 and December 2001, 102 patients were deemed suitable for hip resurfacing. Patients were felt to be suitable if they were active, had no comorbid conditions that might compromise bone quality and were sixty five years old, although this was not an absolute figure. Pre-operative work up was performed to exclude generalised disease that might compromise bone quality, including bone density measurement where appropriate. Baseline Harris hip scores were performed preoperatively and at latest follow up. Operative details were recorded along with per-operative and other complications. Patients were followed up clinically and radiologically at an average of 13 months (range 3–30 months).

Results: There were 86 male and 16 female patients with an average age of 47 (range 28–66) for the men and 48 (range 21–55) for the women. Five patients had acetabular dysplasia as a primary diagnosis, four had AVN, one had post-traumatic arthritis and the remainder had primary osteoarthritis. There were no patients with inflammatory arthritis or severe dysplasia.

Average Harris hip score pre-operatively was 52 (range 25–65). This had improved to 89 at latest follow-up. All operations were performed via an extended posterior approach. No patients had neuro-vascular complications. Average hospital stay was 6.5 days; average transfusion requirement was 0.3 units.

There were two spontaneous femoral neck fractures, both presenting with pain at approximately 2 months. Both were revised to conventionally stemmed femoral components with large metal heads (Corin^TM). One patient presented with pain at 8 months and X-rays showed a fractured neck of femur. At revision, pus was found and diagnosis of infection was assumed. It was treated with a one-stage revision.

93 patients said they were very satisfied with their outcome and two were moderately satisfied. All patients who were more than six months post op (67 patients) had returned to their previous work (41 office work, 16 retailing, 10 farming). Twenty-six patients had returned to active leisure pursuits including running, golf, horse-riding and tennis.

Discussion: When considering new advances in arthroplasty, long-term outcome studies are necessary before any firm conclusion can be drawn regarding ultimate efficacy. This study, however, confirms that BHR is safe and gives good short-term results. While there is no substitute for long-term studies, we feel that these early results are encouraging and justify continued work with the procedure in the context of a critical prospective study.

Introduction: Surgical treatment of unstable fractures of the pelvic ring is a well established technique both to stabilise the ring and reduce bleeding and to facilitate healing in an anatomic position and thereby facilitate rehabilitation. While the pathoanatomic differences between vertically and rotationally unstable fractures are well known, the purpose of this paper is to highlight the difference in expected outcome for these two injuries.

Objective: To review the clinical and radiological outcome following operative treatment of unstable fractures of the pelvic ring and compare the outcome for type B and type C injuries.

Design: Retrospective study of patients treated consecutively with review of initial admission notes and clinical and radiological follow-up.

Patients: From January 1988 to July 1997, one hundred and sixteen patients were treated with traumatic disruption of the pelvic ring. Of these, ninety-five with type B or C fractures required definitive surgical stabilisation of their injuries, forty-five with Tile type B fractures and fifty with Tile type C fractures. There were sixty-three males and thirty-two females with an average age of thirty-three years.

Intervention: All patients had operative treatment for definitive management of pelvic ring disruptions.

Outcome measures: All patients were reviewed clinically and radiologically at a mean of fifty one months. Clinical review consisted of assessment of persistent pain, ability to ambulate, ability to return to work, clinical evidence of persistent instability of mal union. Radiological review was for evidence for mal union or non union.

Results: At final review (mean fifty-one months) ninety-one patients were independently mobile. Of the four patients who required a stick or crutch, two had type B2.1 fractures and two had type C1.3 fractures. Three of these patients had associated acetabular fractures and this may have been contributory.

Sixty patients were completely pain free at follow up. Seventeen patients complained of occasional mild pain after exercise but did not require analgesia. Eleven patients had moderate pain that occasionally required analgesia. Seven patients had severe causalgic type pain, all of who had had evidence of nerve injury at presentation. Only type C fractures with neurologic deficit at presentation had severe pain at follow up. Overall the incidence of pelvic pain, both anterior and posterior, was significantly higher in type C fractures.

There were three non unions, all in type C fractures and one of these required surgery. There were fourteen mal unions, nine leg length discrepancies in type C fractures and five patients with a significant internal rotation deformity of greater than 15° in type B fractures.

Conclusions: The outcome of surgical treatment of unstable pelvic fractures is worse following vertically and rotationally unstable fractures (type C) than after fractures that are only rotationally unstable (type B). This is valuable information when considering the prognosis for these injuries.

Aims: To investigate the prevalence and significance of a high-intensity zone in a group of patients asymptomatic for low back pain.

Methods: A prospective observational study of the prevalence of abnormal MR imaging in normal volunteers without a significant history of back pain. All volunteers underwent physical examination, psychometric testing, plain radiograph, magnetic resonance imaging, and dexa scanning. Films were blindly assessed for the prevalence of degenerative disc disease, osteoporosis, high intensity zone, disc prolapse and spinal stenosis.

Results: Following history, clinical examination and psychometric testing 13 of 63 (20%) patients were excluded from the study on the basis of previous back injury, leg pain or abnormal clinical findings. 50 volunteers were eligible for inclusion in the study. The presence of a high-intensity zone or annular disruption was determined by standardised criteria on T2-wieghted magnetic resonance images. The prevalence of a high-intensity zone in the patient population was 12 of 50 patients (24%). 32% of all disc prolapses were at the L4/5 level, 33% were at L5/S1 and 17% were at L3/4 the remainder were at various other levels.

Conclusions: The presence of a high-intensity zone does not reliably indicate the presence of symptomatic internal disc disruption. Magnetic resonance imaging is accurate in determining nuclear anatomy, however positive findings do not always correlate with history and clinical findings. The presence of abnormal imaging in asymptomatic patients reinforces the need for a detailed history and clinical examination in the evaluation of the lumbar spine.

Introduction: The red, hot swollen knee is commonly seen in the A& E department and can present a diagnostic dilemma for the casualty officer. While superficial cellulites and bursitis are the most common diagnoses, anxiety is induced by the spectre of septic arthritis. The potential sequalae from aspirating a knee through infected superficial tissues further emphasise the importance of making an accurate clinical diagnosis.

The lymph drainage of the superficial tissues of the lower limb is via lymphatics that accompany the long saphenous vein and drain to the lower group of the superficial inguinal nodes. Drainage from the knee joint is to a popliteal node situated between the knee joint capsule and the popliteal artery. Efferents from this node ascend in close relation to the femoral vessels and drains to the deep inguinal nodes. We hypothesise that the differences in lymphatic drainage mean that palpable inguinal nodes are more likely with superficial infections than with septic arthritis. We reviewed the clinical findings in a group of patients with superficial or deep infections to test this theory.

Patients and Methods: From January 1995 until June 2000, twenty-seven patients were admitted with septic arthritis of the knee and fifty-one with superficial cellulites or bursitis about the knee. The former were diagnosed on the basis of clinical findings and a knee aspirate, the latter on clinical findings and response to treatment. The presence or absence of palpable inguinal lymph nodes was determined and compared for each diagnostic group.

Results: Joint aspirates from the group with septic arthritis grew organisms in twenty patients (staph aureus in 19, strep pneumoniae in one). The remaining seven patients had no growth but purulent fluid on aspirate with leukocyte counts in excess of 50,000/mm³. Six patients had rheumatoid arthritis and two were HIV positive IVDA’s but the rest had no pre-disposing factors. The average age was 52 (range 16–83). All were treated with arthroscopic washout (average 2.2/patient) and antibiotic chemotherapy.

In the superficial infection group 28 (56%) had pre-patellar bursitis and 23 (54%) cellulites. All were treated with antibiotics while eight of the bursitis group required incision and drainage. In the patients with superficial infection 32 (63%) had palpable inguinal lymphadenopathy while no patient with septic arthritis of the knee had palpably enlarged inguinal lymph nodes. This result is highly statistically significant (p< 0.01).

Discussion: It is well recognised that neoplastic or inflammatory conditions of the superficial tissues of the lower limb may be associated with inguinal lymphadenopathy. A similar association for septic arthritis of the knee has not to our knowledge been described. Our study would suggest that palpably enlarged lymph nodes are unusual in this condition. While it is worth emphasizing that the presence of lymph nodes does not rule out absolutely the possibility of septic arthritis, their presence or absence may be useful in differentiating superficial from deep infections about the knee.

Introduction: Gait initiation is a sequence of stereotypical postural shifts culminating in a forward step. Muscular and gravitational forces interact leading to appropriate dynamic conditions that allow progression. This requires a complicated system of neural and muscular control. Derangement of ground reaction forces during gait initiation may be a more specific indicator of neuromuscular disease than steady state gait.

Little work has been done on gait initiation in children and there is no published data on gait initiation with cerebral palsy. The aim of this study was to examine the ground reaction forces and centre of pressure in normal children during gait initiation, to compare these to similar values in hemiplegic children and to try to identify differences between the two which may be diagnostic for hemiplegia.

Patients and methods: Five normal and five hemiplegic children were studied. Kinematic and dynamic data were collected using a CodaTM motion analysis system and KestlerTM force plate. All subjects stood with one foot on and one foot off the force plate and walked off upon hearing an audible cue. Tests were repeated measuring right and left, normal and hemiplegic legs as both stance and swing legs. Ground reaction forces in the X,Y and Z axes, centre of pressure and kinematic data were collected and studied.

Results: 1) Normal children. In the vertical direction for the stance leg there is an initial fall in GRF, followed by a bimodal peak in GRF. In the fore-aft direction the GRF is initially directed backwards and subsequently has a bimodal forward force.

Medio-laterally the stance GRF tending to adduct falls initially and subsequently rises with a bimodal peak. The forces in the swing leg reciprocate these forces.

2) Hemiplegic children. The overall pattern seen when the normal leg is the stance leg are similar to those in normal children with certain specific variations in force development and magnitude. When the hemiplegic leg is the stance leg the overall patterns are again similar but considerably less smooth with characteristic changes indicative of neuro-muscular disturbance. The initial “adjusting” forces tend to be larger indicating the greater force required for control.

Discussion: The pattern and relative magnitude of forces measured for normal children are identical to those previously reported for adults. This validates our study design and indicates that central programming for gait initiation develops early in life. It is therefore an early developmental skill and may be used as a diagnostic test in childhood. Significant variations are seen in cerebral palsy. Knowledge of these specific changes may allow earlier and more accurate diagnosis of cerebral palsy in children under investigation for movement disorders. Normal GRF patterns during gait initiations may provide early reassurance for parents of children suspected of having cerebral palsy.

We have carried out a blind, prospective study of 50 consecutive patients undergoing replacement arthroplasty of the hip using two different approaches. Clinical assessment, including the Harris hip score and a modified Trendelenberg test, and electrophysiological examination of the abductor muscles of the hip were undertaken before and three months after surgery. We found that 48% of patients had preoperative evidence of chronic injury to the superior gluteal nerve. Perioperative injury to the nerve occurred commonly with both approaches to the hip.

We did not find a significant correlation between injury to the superior gluteal nerve and clinical problems.