Mechanical function and failure of intervertebral discs. In a healthy disc, the nucleus pulposus acts like a pressurised fluid which is restrained by tensile stress within the annulus. With increasing age, the nucleus becomes more fibrous, and biochemical changes cause the whole disc to become less elastic, and more yellow in colour. Mechanically, the hydrostatic nucleus shrinks with age, and concentrations of compressive stress appear in the posterior annulus. Experiments on cadaveric spines have shown that healthy discs can prolapse when loaded severely or repetitively in bending and compression, and that internal disruption of the disc probably follows damage to the vertebral endplates. However, mechanical loading is not necessarily harmful to living discs: on the contrary, moderate repetitive loading may lead to disc hypertrophy rather than injury. Disc degeneration. Degeneration represents some mechanical or biological “insult” superimposed on normal ageing. A defining feature of “degeneration” should be structural failure of the annulus or endplate, because all degenerated discs exhibit structural failure whereas many old discs do not. Degeneration creates high stress concentrations within the annulus. Paradoxically, severe degeneration can lead to gross disc narrowing and reduced stresses in the annulus, presumably because it is “stress shielded” by the apophyseal joints. Animal experiments show that disc degeneration always follows mechanical disruption. In some cases, it may possibly precede it. Disc degeneration and back pain. Pain-provocation studies have shown that severe and chronic back pain often originates in the posterior annulus fibrosus, and can be elicited by relatively moderate mechanical pressure. Anatomical studies indicate that the outer annulus is supplied with complex and free nerve endings from the mixed sinuvertebral nerve. MRI and discographic studies show that back pain is closely correlated with structural features of disc degeneration such as radial fissures and prolapse, although age-related changes in composition are clinically irrelevant. The stress-shielding of severely degenerated discs (see above) suggests that discogenic pain may be most closely associated with intermediate stages of degeneration. The localised stress concentrations found in degenerated cadaveric discs have been directly linked to low back pain in living people. Medico-legal implications. The widely-held belief that a disc will not prolapse unless it is degenerated is no longer compatible with the scientific evidence. Severe loading, which in life usually arises from vigorous muscle contractions, can injure normal discs. On the contrary, it seems likely that severely degenerated discs are too fibrous to prolapse, and that many of the cell-mediated changes associated with disc prolapse occur after prolapse, rather than before. However, genetic inheritance is important in disc degeneration and prolapse, suggesting that some discs are more vulnerable than others to mechanical loading. The nature of this vulnerability is largely unknown, but is likely to involve genetic weaknesses in composition, and previous fatigue damage. It would be desirable to distinguish between these last two factors, but this is likely to prove difficult in practice

The number of total knee arthroplasties continues to increase annually with over 90,000 total knee replacements performed in the United Kingdom in 2018. Multiple national bodies including the British Association for Surgery of the Knee (BASK) and the British Orthopaedic Association collaborated in July 2019 to produce best practice guidance for knee arthroplasty surgery. This study aims to review practice in a regional healthcare trust against these guidelines.

Fifty total knee replacement operation notes were reviewed between January and February 2020 from 11 different consultant orthopaedic surgeons. Documents were assessed against 17 criteria recommended by the BASK guidance. Personnel names and grades were generally well documented. Tourniquet time and pressure were documented in over 98% of operation notes however, protection from spirit burns was not documented at all. Trialling and soft tissue balancing was well recorded in 100% and 96% of operation notes respectively.

Areas lacking in documentation included methods utilised to optimise cementation technique and removal of cement debris. Protection of key knee structures was documented in only 56% of operation notes clearly. Prior to closure, final assessment of mechanism integrity, collateral ligament was not documented at all and final ROM after implantation of components was recorded 34% of the time.

Subsequently authors have created a universal operation note template, uploaded onto the patient electronic notes, which prompts surgeons to complete documentation of the relevant criteria advocated by BASK.

In conclusion, detailed and systematic documentation is vital to prevent adverse events and reduce the risk of litigation. By producing detailed operative templates this risk can be mitigated.

Despite tendencies for Claims against medical practitioners around Australia to fall, litigation continues to be a burden on individual practitioners and the system.

Unlike Claims frequency, Claims costs are not falling and indemnity insurance remains a significant practice cost.

Data is presented to illustrate some trends in litigation and illustrative cases are also presented to outline some of the difficulties in defending Claims.

Particular emphasis on the degree of difficulty is made in respect of Epidural Abscess.

Objective. Guidelines published by the British Association of Spine Surgeons (BASS) and Society of British Neurological Surgeons (SBNS) recommend urgent MRI imaging and intervention in individuals suspected of having CES. The need for an evidence based protocol is driven by a lack of 24/7 MRI services and centralisation of neurosurgery to tertiary centres, compounded by CES's significant medico-legal implications. We conducted an audit to evaluate the pathway for suspected CES in BCUHB West between 2018 and 2021. Methods. A retrospective audit of patients managed for suspected CES between 01/11/2018 and 01/05/2021 was performed, using the SBNS/BASS guidelines as the standard. Results. A total of 252 patients received an emergency MRI for suspected CES between 2018 and 2021. 99% of patients were scanned in compliance with SBNS/BASS standards. Radiological evidence of CES was found in 18% of patients. 33% of emergency scans were performed by out-of-hours services. 4% of patients had repeated scans within the same 6-month period. The majority of referrals originated from Orthopaedics surgeons (78%), or staff in the Emergency Department (8%). 92% of ambulatory patients were not admitted to hospital. During the peak of the COVID-19 pandemic, referrals increased from 2.5 to 3.5 per week. Conclusion. SBNS/BASS standards were largely met, avoiding life changing disability and medico-legal consequences. The department should continue to follow SBNS/BASS guidance on the management of individuals with suspected CES. Challenges regarding the use of repeated scans should be addressed to avoid unnecessary costs. Introduction of new early recognition guidelines and Same Day Emergency Care (SDEC) has likely driven an increase in suspected CES referrals, and subsequent MRI demand. This audit should be utilised as an ongoing tool to ensure best practice continues, and to implement simple measures which may improve compliance with the pathway

Acute post-operative urinary retention (POUR) is a recognized complication following lower limb arthroplasty. Its occurrence may have patient and ultimately medico-legal implications. Identifying high-risk patients and the associated risk factors pre-operatively, is vital to tackle this issue and reduce its occurrence, which ultimately, may enhance the overall success of our operations. Our aim was to assess the incidence of POUR following elective lower limb arthroplasty and analyze the related factors that could potentially predict the likelihood of developing POUR in our patient cohort. A prospective audit of 158 patients was conducted in our department. POUR was defined as inability to pass urine voluntarily within the first 24 hours following elective lower limb arthroplasty leading to the insertion of a urinary catheter. Surgical-related factors including intra-operative fluid use, type of spinal anesthetic, duration of surgery, time from surgery till insertion of a urinary catheter as well as patient-related factors including medication, urological history and Body Mass index (BMI) was collected and analyzed. 21 (13.3%) patients developed post-operative urinary retention, 11 (52%) and 10 (48%) following knee and hip replacements respectively. Of which, 19 (90.5%) were male and 2 (9.5%) were female with an average age of 66 yrs. 13 (62%) had a previous urological history and 10 (48%) were on retention associated medication. Bupivacaine as a spinal anesthetic was associated with an increased risk of developing post-operative urinary retention. The average time till catheter insertion was 14 hrs. Only 2 (10%) had an unsuccessful TWOC on discharge. Bupivacaine as a spinal anesthetic and a previous urological history can be considered as risk factors for the development of POUR. Pre-operative urinary catheterization should be considered in this high-risk group of patients

Introduction. Appropriate consenting is part of good medical practice and is a medico-legal necessity for invasive procedures. The BOA recently created generic consent forms covering the relevant complications for orthopaedic procedures, thus providing a standard for all orthopaedic consent. This study aims to assess the quality of consent in orthopaedic practice. Materials/Methods. The most common elective and trauma procedures were identified over a one year period and consent forms for all patients undergoing these procedures were assessed against BOA ortho-consent forms. Data was compiled from elective total hip replacements (THR) and trauma ankle open reduction and internal fixations (ORIF), and analysed in excel. Results. Forty ORIF's and forty-one THR's were considered totalling eighty-one cases. The average percentage of total complications included per form was 50%. Consultants had a higher average percentage of documented complications to all other grades (56%)(graph 1). Elective cases had a higher percentage of total complications included (59%) than trauma cases (40%). All consent forms included the risk of infection. Only 2.5% of THR consent forms included the risk of death and none of the ORIF consent forms included the risk of numbness post-op. All other complications were variably included (graphs 2 and 3). The most common grade to fill in consent forms were SHO's making up 60% of the forms (Chart 1). Conclusion. Consent forms are not being filled in appropriately. This is a medico-legal risk we should be aware of and we would recommend the use or provision of ortho-consent forms as routine practice

The aim of this study was to investigate the long-term outcome of isolated, displaced Lisfranc injuries requiring operative intervention and identify whether results of treatment are influenced by workers compensation. This retrospective study reviewed all patients who underwent operative intervention for Lisfranc injuries. Patients with concomitant injuries were excluded from further investigation so that the outcome of purely isolated Lisfranc injuries could be assessed. The minimum follow-up was two years and the senior author performed all the operations. Patients were contacted and their employment status recorded. Ordinal regression analysis was performed to identify which factors influenced the outcome. Forty-six patients were studied and 24 had pursued medico-legal claims. The average Workcover payment was Aus$25,000 (£10,000). Thirteen of forty-six patients had a poor outcome. Eleven of these patients had compensation claims (p< 0.01) and 11 had greater than a three month delay in treatment following diagnosis (p< 0.05). Although 12/33 men and 1/13 women had a poor outcome this difference was not statistically significant. The need for secondary fusion was not associated with a poor outcome. There was no significant difference between outcome and mechanism of injury or previous occupation. There was no correlation between the outcome and age at the time of injury. This series of 46 patients has a long follow-up of a rare injury. We believe that this study has medico-legal implications on reporting prognosis for such injuries and highlights the importance of prompt diagnosis and treatment for such injuries

Purpose: Litigation continues to be a concern in orthopaedic surgery despite suggestions on how to contain liability. The purpose of this study was to characterize orthopaedic litigation in Canada from 1997–2006. Method: This study reviewed all closed claims reported to the Canadian Medical Protective Association (CMPA) for 1997–2006 in which orthopaedic surgeons were named. There were 11,983 closed legal actions involving CMPA members (> 73,000 physicians), and 1,353 involved orthopaedic surgeons. A careful review of closed legal actions is a recognized tool for risk identification, assessment and management. The CMPA identifies any critical incidents within the closed legal files. A critical incident is defined as any omission or commission in the evaluation or management which led to the problem(s) that triggered the legal action. Each closed legal action can have more than one critical incident. Results: Performance, diagnostic and communication issues were the most frequently identified problems. These three areas account for 55% of the critical incidents identified. Performance related issues accounted for 395 critical incidents (29%). Diagnostic issues, including deficient histories and general evaluations, were identified in 281 cases (21%). Communication-related critical incidents included those concerning informed consent. The lack of informed consent was a common allegation, proven in 71 cases. In 439 cases (32%) there was no identifiable critical incident for the orthopaedic surgeon involved. Seventy-eight per cent of patients experienced minor or no disability and 22% experienced major disability or death. Events related to tibia trauma and knee arthroscopy formed the two major categories of claims. Patient care areas of high risk include the operating room and outpatient clinic. Overall, 31% of legal actions against orthopaedic surgeons had outcomes in favour of the plaintiffs, compared with 33% of all CMPA members’ claims. Conclusion: Although the likelihood for an orthopaedic surgeon to be sued in Canada has decreased over the last 10 years, the percentage of legal cases resolved in favour of plaintiffs has remained stable. Performance-related deficiencies, delays in diagnosis, and failures in communication represent areas of high medico-legal risk. Suggestions for risk management are provided to further decrease adverse events and the medico-legal risks for Canadian orthopaedic surgeons

All skeletally immature patients who presented with a supracondylar fracture between 01/09/2013 and 24/11/2015 (n = 50) were used to compare the current management of supra-condylar fractures of the humerus in children to the standards set by the BOAST 11 guidelines. 8.1% did not have full documentation of their neurovascular assessment. 93.9% underwent surgery within 24 hours of presentation. Average time to theatre for neurovascularly compromised patients was 4 hours 46 minutes. 81.8% were managed with 2 K-wires as recommended. Only 39.4% of the patients had their wires removed within 3 – 4 weeks. Only 6.1% had the recommended 2 mm wires. AO recommends the use of 2mm wires if 2 lateral wires are used whereas the BOAST 11 guideline recommends 2mm wires where possible. The results clearly demonstrate a need for further education and awareness of the BOAST 11 guidelines. Of particular interest is the documentation of patients' neurovascular status for appropriate management and for medico-legal purposes. Long term outcome comparison of surgical fixation with 2mm and 1.6mm wires would be useful to support the use of 2mm wires as recommended by the professional consensus in the BOAST 11 guidelines

In a society whereby the incidence of obesity is increasing and medico-legal implications of treatment failure are more frequently ending with the consulting doctor, clarity is required as to any restrictions placed on common orthopaedic implants by manufacturing companies. The aim of this study was to identify any restrictions placed on the commonly used femoral stem implants in total hip replacement (THR) surgery, by the manufacturers, based on patient weight. The United Kingdom (UK) National Joint Registry (NJR) was used to identify the five most commonly used cemented and uncemented femoral stem implants during 2012. The manufacturing companies responsible for these implants were asked to provide details of any weight restrictions placed on these implants. The Corail size 6 stem is the only implant to have a weight restriction (60Kg). All other stems, both cemented and uncemented, were free of any restrictions. Fatigue fracture of the femoral stem has been well documented in the literature, particularly involving the high nitrogen stainless steel cemented femoral stems and to a lesser extent the cemented cobalt chrome and uncemented femoral stems. In all cases excessive patient weight leading to increased cantilever bending of the femoral stem was thought to be a major factor contributing to the failure mechanism. From the current literature there is clearly an association between excessive patient weight and fatigue failure of the femoral stem. We suggest avoiding, where possible, the insertion of small stems (particularly cemented stems) and large offset stems (particularly those with a modular neck) in overweight patients

Aim. Implant-related infections, including peri-prosthetic joint infection (PJI) and infected osteosynthesis, are biofilm-related. Intra-operative diagnosis and pathogen identification is currently considered the diagnostic benchmark; however the presence of bacterial biofilm(s) may have a detrimental effect on pathogen detection with traditional microbiological techniques. Sonication and chemical biofilm debonding have been proposed to overcome, at least partially, this issue, however little is known about their possible economical impact. Aim of this study was to examine direct and indirect hospital costs connected with the routine use of anti-biofilm microbiological techniques applied to hip and knee PJIs. Method. In a first part of the study, the “Turn Around Time (TAT)” and direct costs comparison between a system to find bacteria on removed prosthetic implants. *. , a closed system for intra-operative tissue and implant sampling, transport and anti-biofilm processing, versus sonication has been performed. An additional analysis of the estimated indirect hospital costs, resulting from the diagnostic accuracy of traditional and anti-biofilm microbiological processing has been conducted. Results. Considering an average 5 samples per patient, processed separately with the sonication or pooled together, using the device. *. , the direct costs comparison shows a similar overall average estimated cost per patient when using sonication (€ 400.00) or the system to find bacteria on removed prosthetic implants. *. (€ 391.70). Indirect hospital costs of false positive or negative intra-operative pathogen identification can be estimated as, respectively, € 65,000 and € 90,000, including possible inadequate treatments and/or surgeries and/or need for further hospital stay, risk of infection recurrence/persistence, possible medico-legal claims, etc. Considering 1 out of ten cases of false identification as generating indirect hospital costs (“mitigation factor”: 90%) and an accuracy of current intra-operative microbiological sampling and testing of approximately 80%, it is calculated that any anti-biofilm procedure able to increase the microbiological diagnostic accuracy by 10%, at an average cost per patient of € 500.00, would induce an average hospital cost saving of approximately € 100,000 per 100 treated cases. Conclusions. To our knowledge, this is the first study specifically focused on the potential economical impact of the routine clinical use of microbiological anti-biofilm processing techniques in orthopaedics. The several limitations of this study notwithstanding, including the variable Country-based value of the different direct costs and the assumptions made concerning indirect costs calculations, this analysis points out how more accurate pathogen identification procedures can lead to an improvement of the management of implant-related infections in orthopaedics, with a substantial economical balance

Background. The British Orthopaedic Association Standards for Trauma (BOAST) for peripheral nerve injuries. 1. states:. “A careful examination of the peripheral nervous and vascular systems must be performed and clearly recorded for all injuries. This examination must be repeated and recorded after any manipulation or surgery.”. This study investigated whether this standard was met for patients with upper limb trauma at a busy London Accident and Emergency (A&E) Department. Method. Data was gathered prospectively from A&E admission notes for 30 consecutive patients with upper limb injuries from the week beginning 11. th. March 2013. Eligibilty: All patients with upper limb injuries. Results. 30 patients: 18 Males mean age of 39.2 and 12 Females mean age of 40.1. 17 patients (56.6%) had documentation of examination of neurovascular status. 14 patients required manipulation and/or splinting of their injury. Of these, no patients had their neurovascular examination documented after the procedure. Poor adherence to the standard is evident across all grades of doctors: FY2, SHO and SpR. Conclusion. There is clear scope to improve documentation of neurovascular status in upper limb injuries. It is especially important to clearly document neurovascular status following manipulation or splinting from a medico-legal perspective. This applies to all grades of staff in A&E. Recommendations. 1. Education of A&E staff of all grades at the departmental induction. 2. Posters in A&E with simple treatment algorithm for managing fractures and dislocated joints. 3. Re-audit in 6 months

The aim of this study was to review the data held with the NHSLA database over the last 10 years for negligence in spine surgery with particular focus on why patients ‘claim’ and what is the likely outcome. Anonymous retrospective review. We contacted the NHSLA and asked them to provide all data held on their database under the search terms ‘spine surgery or spine surgeon.’. An excel sheet was provided, and this was then studied for reason of ‘claim’, whether the claim was open/closed and outcome. A total of 67 claims of negligence were made against spinal surgeries during this time (2000-09). The number of claims had increased over the last few years: 2000-03, n= 8, 2004-06, n= 46. The lumbar spine remains the most common area (Lumbar: 55/67, Thoracic : 6/67, Cervical 6/67). Documented reasons for claims were post-operative complications (n= 28; 42%), delayed/failure to diagnose (n=24; 36%), discontent with preoperative assessment including consent (n=2; 3%), intra-operative complications (n= 10; 15%) and anaesthesia complication (n=3; 4%). Twenty were closed and 47 remained open. The number of successful claims was 8/20 (40%). The mean compensation paid out was £33,409 (range was £820.5 to £60,693). The number of claims brought against spinal surgeries is on the increase, with the most common area being the lumbar spine which perhaps is not surprising as this is the most common area of spinal surgery. Common reasons are post-operative complications and delay/failure to diagnose. The ‘success’ of these claims over the last 10 years was 8/20 (40%) with mean compensation paid out was £33,409. Ethics approval: None;. Interest Statement: The lead author is the CEO and founder of a Personal Injury/Medico-Legal company

The aim of this paper is to stress that an expert providing medico-legal opinion in matters relating to medical malpractice, workers compensation, transport accident and other injuries should preferably be a recognised expert in the field by virtue of knowledge, training, qualification and experience, free from bias as far as is possible and willing to provide evidence if called to court. Based on over ten years experience of conducting what is now largely a medicolegal practice and recently having obtained a Post Graduate Diploma in Health/Medical Law from Melbourne University and with approximately 800 assessments conducted yearly over that period, requirements for taking a comprehensive history, carrying out a thorough physical evaluation as well as assessment of all appropriate investigations and writing a “stand alone” medicolegal report will be outlined. Also included in the final opinion should be comments on opinions given by other experts. One should also include the summarised opinion in the world literature relating to the main issue. Finally, just as a judge does when giving his judgement the reasons underlying the opinion should be fully explained. Judges throughout Australia conducting medical lists are concerned that many medical assessments appear to be biased towards the party requesting and paying for the report; ways of reducing bias will be suggested. Finally the author will give his views on the value of expert medical panels independently appointed by the courts through the learned medical colleges giving their opinion on liability and whole person impairment in medical malpractice claims, and similar to medical panels currently assessing workers compensation injury in most states in Australia

The rate of litigation following personal injury is rising at an exponential rate with no concomitant rise in the actual incidence of these injuries. It is recognised that physical injury can lead to mental health disturbance and such mental health disturbance can delay recovery following injury. No previous study has assessed the incidence of pre-existing mental health morbidity amongst personal injury claimants. The general practitioners records of 750 consecutive personal injury claimants were examined. Mental health diagnoses prior to the index injury were noted and classified using the Diagnostic and Statistical Manual of the American Association of psychiatry. Any treatment by mental health professionals was noted. A highly significant excess of pre-injury psychiatric morbidity was identified in the study population. There was a 40% incidence of at least one mental health diagnosis. There was a highly significant excess of depression and anxiety. 10% of the study group had received treatment from at least one mental health professional. Pre-existing psychiatric morbidity appears to be an independent predictive factor for pursuing litigation following personal injury. In light of existing knowledge that such psychiatric morbidity often results in prolongation of physical symptoms and poor response to standard treatment regimes, it is important to recognise such patients when providing a prognosis in a medico-legal context

The purpose of the study was to determine the percentage of knowledge retained immediately following an outpatient consultation for total hip and knee joint arthroplasty, and whether any improvement in that knowledge occurred after reading an information leaflet about the operation. Patients who were placed on the waiting list for joint replacement surgery, were verbally given information during the consultation about basic operative details, post-operative programme, and potential complications. A questionnaire was completed asking them to recall these details. Information leaflets were then given to them to read. 6 weeks later they were again contacted and asked the same questions. Immediately following a consultation, patients recall only a small percentage of information. In particular, retention of post-operative recovery time frames (51–63%), and possible operative complications (0–61 %). Despite an information booklet, their level of knowledge deteriorates from the initial consultation. Verbal and written information supplied to a patient, may be understood, but it is easily and quickly forgotten. In an increasingly medico-legal environment it is essential to gain an informed consent from a patient when performing interventions. The provision of an information booklet may provide nothing more than proof for the surgeon of information provision to the patient

Aim. To compare spinal outcome measures between patients reviewed for medico-legal compensation claims relating to perceived injury at work to those having sustained serious structural injury in the form of unstable thoraco-lumbar fractures requiring internal fixation. Method. Two consecutive cohorts of 23 patients with healed spinal fractures and 21 patients with a perception of work related soft tissue injury were compared. Patient demographics and a range of outcome measures including Oswestry Disability Index (ODI), Low Back Outcome score (LBOS), Modified Somatic Perception (MSP) and Modified Zung Depression (MZD) indices were measured. Results. 23 patients (8F; 15M) with spinal fractures (group 1) of average age 42 years (range 22-66) were followed up for a mean of 41 months (range 14-89, SD 23.3) post trauma and compared to 21 patients (6 females; 15 males) with self reported back pain (group 2) of average age 47 years (range 37-63), mean time since perceived injury of 42 months (range 12-62, SD 14.5). Both groups were comparable in terms of age and sex (P = 0.254 and 0.752 respectively). The average ODI was 28% (SD 18.5) compared to 52% (SD 17.1) in group 1 and 2 respectively (P value: 0.000087); LBOS 40 Vs 20 (P=0.000189); MSP 4 Vs 10 (0.01069); and MZD 20 Vs 36 (P=0.000296). Conclusion. Despite high energy trauma and significant structural damage to the spine, post-traumatic patients had better spinal outcome scores in all measures (ODI, LBO, MSP, MZD). This thereby defies 8 of the 9 Bradford Hill criteria of causation. The reasons for such differences are primarily psychosocial. Addressing obstacles to recovery may improve outcomes. There is no ‘dose-response’ curve to functional outcomes. In fact, uniquely the disability seems greater in the lower energy injury which is unique in trauma care

Introduction and Aims: Lower back and/or leg pain is a symptom of a number of pathological conditions involving lumbosacral nerve roots. Disc herniation is one of the most common causes of LBP (after mechanical back pain). There is controversy regarding the progression of disc degeneration and/or lower back pain to symptomatic disc prolapse over time. Method: The aim of the study was to determine the natural progression of patients with lower back pain/disc degeneration established clinically and on MRI to symptomatic disc herniation over three to six years. Total of 970 patients who had an MRI scan between January 1998 and September 2000 were included in the study. Information about disc pathology, level and number of discs involved were recorded from MRI scan reports. A short questionnaire was sent to all patients. It contained 10 questions regarding current status of pain and neurology, any treatment in form of back injection and operation, current occupation and smoking status. Results: The collected data was analysed using standard statistics software (SPSS). The results will be discussed. Conclusion: The information provided by this study will be useful in judging the natural progression of lower back pain and/or disc degeneration to a symptomatic prolapse intervertebral disc. It will also be useful in medico-legal cases where patients had pre-existing disc degeneration and subsequently developed disc herniation over time

Introduction: Age related histological and radiological changes are widespread in the lumbar spine. The correlation with symptoms is poor and there is good evidence that in later decades the incidence of back symptoms decreases, despite the relentless progression of radiological abnormalities. Much confusion exists regarding Accident Compensation Corporation (ACC) insurance entitlement following injuries in the presence of asymptomatic but existing radiological ageing changes (spondylosis) and existing but asymptomatic spondylolysis/isthmic spondylolisthesis. Aim: To review the relevant literature and ACC Acts to clarify the ACC Act definition of injury/accident and exclusion criteria and the natural history of spondylosis/spondylolysis/spondylolisthesis, in relation to patients sustaining new lumbar spine injuries in the presence of existing but asymptomatic radiological abnormalities. Method: The relevant literature and legislation (1992 ARCI and 1998 AI Acts) were reviewed. Results: Regarding spondylolysis and low grade isthmic spondylolisthesis the literature is conflicting in relation to the incidence of back symptoms. The ACC Acts do not discuss existing disorders or degenerative conditions, but focus on exclusion of cover for ‘personal injury caused wholly or substantially by the ageing process’. Conclusions: As with clinical decision making medico-legal assessment requires a meticulous history as the primary focus. It is inappropriate to apportion undue weight to radiological abnormalities that correlate poorly with symptoms

Introduction Both congenital and acquired aetiologies for Os Odontoideum have been proposed leading to confusion in a medico-legal setting. No large series with CT and MRI features has been reported. Methods Clinical, radiological, CT and MRI data from 25 cases of cranio-cervical anomalies (including 18 with Os Odontoideum) was collected prospectively. The hypothesis that Os Odontoideum is associated with signs of dysplasia such as arch hypertrophy (as quantified by the arch-peg ratio) and a ‘jigsaw’ like atlanto-dens joint configuration was tested. Results Only one of 18 cases with Os Odontoideum gave a history of remote trauma. None of the cases with other post traumatic conditions showed arch hypertrophy or dysplasia of the joint. Os Odontoideum was associated with two distinctive features on mid-sagittal CT reconstruction: arch hypertrophy and the presence of a ‘jigsaw sign’. A quantitative definition of arch hypertrophy (an arch/ peg ratio greater than 0.5) provided a sensitive and specific test for Os Odontoideum. This was further enhanced in combination with the jigsaw sign to give a test accuracy of 97%. Motor changes with MRI signs of cord damage were observed in one of 12 cases associated with trauma. Conclusions The lack of a history of remote trauma and the dyplastic atlanto-dens joint seen on CT are more suggestive of a congenital than a post-traumatic aetiology for Os Odontoideum. Patients with Os odontoideum are able to tolerate moderate to severe levels of injury without sustaining significant acute cord damage