The prevalence of cam hip morphology in a general population sample.

OBJECTIVE: Cam hip morphology is associated with femoroacetabular impingement (FAI) syndrome and causes hip osteoarthritis (OA). We aimed to assess the prevalence of cam hip morphology in a sample representative of the general population, using a measure with a predefined diagnostic accuracy. DESIGN: Patients aged 16-65, who were admitted to a major trauma centre and received a computed tomography (CT) pelvis were retrospectively screened for eligibility. Subjects with proximal femoral, acetabular or pelvic fractures and those who were deceased were excluded. Eligible subjects were divided into 10 groups based on gender and age. 20 subjects from each group were included. Subjects' index of multiple deprivation (IMD) and ethnicity were recorded. CT imaging was assessed and alpha angles (a measure of cam morphology) measured in the anterosuperior aspect of the femoral head neck junction. An alpha angle greater than 60° was considered to represent cam morphology. This measure and technique has a predefined sensitivity of 80% and specificity of 73% to detect cam morphology associated with FAI syndrome. The prevalence of cam morphology was reported as a proportion of subjects affected with 95% confidence intervals. RESULTS: 200 subjects were included. The sample was broadly representative of the UK general population in terms of IMD. 155 subjects (86%) identified as white. Cam morphology was present in 47% (95% CI 42,51) of subjects. CONCLUSIONS: In this sample, broadly representative of the UK general population 47% of subjects had cam hip morphology; a hip shape associated with FAI syndrome and OA.

Prevalence of cam hip shape morphology: a systematic review.

OBJECTIVE: Cam hip shape morphology is a recognised cause of femoroacetabular impingement (FAI) and is associated with hip osteoarthritis. Our aim was to systematically review the available epidemiological evidence assessing the prevalence of cam hip shape morphology in the general population and any studied subgroups including subjects with and without hip pain. DESIGN: All studies that reported the prevalence of cam morphology, measured by alpha angles, in subjects aged 18 and over, irrespective of study population or presence of hip symptoms were considered for inclusion. We searched AMED, MEDLINE, EMBASE, CINAHL and CENTRAL in October 2015. Two authors independently identified eligible studies and assessed risk of bias. We planned to pool data of studies considered clinically homogenous. RESULTS: Thirty studies met inclusion criteria. None of the included studies were truly population-based: three included non-representative subgroups of the general population, 19 included differing clinical populations, while eight included professional athletes. All studies were judged to be at high risk of bias. Due to substantial clinical heterogeneity meta analysis was not possible. Across all studies, the prevalence estimates of cam morphology ranged from 5 to 75% of participants affected. We were unable to demonstrate a higher prevalence in selected subgroups such as athletes or those with hip pain. CONCLUSIONS: There is currently insufficient high quality data to determine the true prevalence of cam morphology in the general population or selected subgroups. Well-designed population-based epidemiological studies that use homogenous case definitions are required to determine the prevalence of cam morphology and its relationship to hip pain.

Temporary abolition of pain in man.

In eight patients with intense chronic cutaneous pain, sensory nerves or roots. supplying the painful area were stimulated. Square-wave 0.1-millisecond pulses at 100 cycles per second were applied, and the voltage was raised until the patient reported tingling in the area. During this stimulation, pressure on previously sensitive areas failed to evoke pain. Four patients, who had diseases of their peripheral nerves, experienced relief of their pain for more than half an hour after stimulation for 2 minutes.

Ceramic-on-ceramic bearing fractures in total hip arthroplasty: an analysis of data from the National Joint Registry.

AIMS: Ceramic-on-ceramic (CoC) bearings in total hip arthroplasty (THA) are commonly used, but concerns exist regarding ceramic fracture. This study aims to report the risk of revision for fracture of modern CoC bearings and identify factors that might influence this risk, using data from the National Joint Registry (NJR) for England, Wales, Northern Ireland and the Isle of Man. PATIENTS AND METHODS: We analysed data on 223 362 bearings from 111 681 primary CoC THAs and 182 linked revisions for bearing fracture recorded in the NJR. We used implant codes to identify ceramic bearing composition and generated Kaplan-Meier estimates for implant survivorship. Logistic regression analyses were performed for implant size and patient specific variables to determine any associated risks for revision. RESULTS: A total of 222 852 bearings (99.8%) were CeramTec Biolox products. Revisions for fracture were linked to seven of 79 442 (0.009%) Biolox Delta heads, 38 of 31 982 (0.119%) Biolox Forte heads, 101 of 80 170 (0.126%) Biolox Delta liners and 35 of 31 258 (0.112%) Biolox Forte liners. Regression analysis of implant size revealed smaller heads had significantly higher odds of fracture (chi-squared 68.0, p < 0.001). The highest fracture risk was observed in the 28 mm Biolox Forte subgroup (0.382%). There were no fractures in the 40 mm head group for either ceramic type. Liner thickness was not predictive of fracture (p = 0.67). Body mass index (BMI) was independently associated with revision for both head fractures (odds ratio (OR) 1.09 per unit increase, p = 0.031) and liner fractures (OR 1.06 per unit increase, p = 0.006). CONCLUSIONS: We report the largest independent study of CoC bearing fractures to date. The risk of revision for CoC bearing fracture is very low but previous studies have underestimated this risk. There is good evidence that the latest generation of ceramic has greatly reduced the odds of head fracture but not of liner fracture. Small head size and high patient BMI are associated with an increased risk of ceramic bearing fracture. Cite this article: Bone Joint J 2017;99-B:1012-19.

A pragmatic randomised controlled trial comparing the efficacy of a femoral nerve block and periarticular infiltration for early pain relief following total knee arthroplasty.

AIMS: The aim of this study was to compare the effectiveness of a femoral nerve block and a periarticular infiltration in the management of early post-operative pain after total knee arthroplasty (TKA). PATIENTS AND METHODS: A pragmatic, single centre, two arm parallel group, patient blinded, randomised controlled trial was undertaken. All patients due for TKA were eligible. Exclusion criteria included contraindications to the medications involved in the study and patients with a neurological abnormality of the lower limb. Patients received either a femoral nerve block with 75 mg of 0.25% levobupivacaine hydrochloride around the nerve, or periarticular infiltration with 150 mg of 0.25% levobupivacaine hydrochloride, 10 mg morphine sulphate, 30 mg ketorolac trometamol and 0.25 mg of adrenaline all diluted with 0.9% saline to make a volume of 150 ml. RESULTS: A total of 264 patients were recruited and data from 230 (88%) were available for the primary analysis. Intention-to-treat analysis of the primary outcome measure of a visual analogue score for pain on the first post-operative day, prior to physiotherapy, was similar in both groups. The mean difference was -0.7 (95% confidence interval (CI) -5.9 to 4.5; p = 0.834). The periarticular group used less morphine in the first post-operative day compared with the femoral nerve block group (74%, 95% CI 55 to 99). The femoral nerve block group reported 39 adverse events, of which 27 were serious, in 31 patients and the periarticular group reported 51 adverse events, of which 38 were serious, in 42 patients up to six weeks post-operatively. None of the adverse events were directly attributed to either of the interventions under investigation. CONCLUSION: Periarticular infiltration is a viable and safe alternative to femoral nerve block for the early post-operative relief of pain following TKA. Cite this article: Bone Joint J 2017;99-B:904-11.

Do nerve impulses penetrate terminal arborizations? A pre-presynaptic control mechanism.

Is there clear evidence that action potentials travelling in a parent axon reach all of their terminals? In spinal afferents, many fibres extend their arborizations beyond the area in which cells can be shown to respond to the afferents. In addition, impulses fail to propagate in the long-range reach of myelinated fibres in dorsal columns when a GABA-operated Cl- shunt in the terminals is operating. When the mechanism is immobilized by antagonists of GABAA receptors, impulse blockade is relieved. This suggests an additional control mechanism, which is located in axons proximal to the synaptic area. Such a control could focus or defocus those parts of a terminal arborization that affect postsynaptic cells.

Does the right side know what the left is doing?

Following peripheral-nerve lesions there are well-documented events that affect the contralateral nonlesioned structures. These contralateral effects are qualitatively similar to those occurring at the ipsilateral side, but are usually smaller in magnitude and have a briefer time course. It is unclear whether the findings are an epiphenomenon or serve a biological purpose, but in either case the existence of these effects implies the presence of unrecognized signalling mechanisms that link the two sides of the body. Strong circumstantial evidence argues against a peripheral mechanism (for example, via circulating factors) and in favour of a central mechanism, in particular signalling via the system of commissural interneurons that is present in spinal cord and brainstem. While an altered pattern of activity in this system might underlie the phenomenon, there are several reasons for proposing that the changes depend upon chemical signals, possibly growth factors. Because of its relative easy access for experimental manipulation, the spinal cord could serve as a model system to study these transmedian signalling systems.

Central hyperexcitability triggered by noxious inputs.

Repetitive activity in unmyelinated sensory afferent neurones, arising from electrical stimuli, tissue injury or nerve damage, can induce long-lasting sensitization in dorsal horn neurones. This process can be blocked by antagonists of the NMDA receptor. In the past year it has emerged that sensory neuropeptides and nitric oxide are also essential mediators of this phenomenon.

The feasibility of conducting a randomised controlled trial comparing arthroscopic hip surgery to conservative care for patients with femoroacetabular impingement syndrome: the FASHIoN feasibility study.

To determine whether it was feasible to perform a randomized controlled trial (RCT) comparing arthroscopic hip surgery to conservative care in patients with femoroacetabular impingement (FAI). This study had two phases: a pre-pilot and pilot RCT. In the pre-pilot, we conducted interviews with clinicians who treated FAI and with FAI patients to determine their views about an RCT. We developed protocols for operative and conservative care. In the pilot RCT, we determined the rates of patient eligibility, recruitment and retention, to investigate the feasibility of the protocol and we established methods to assess treatment fidelity. In the pre-pilot phase, 32 clinicians were interviewed, of which 26 reported theoretical equipoise, but in example scenarios 7 failed to show clinical equipoise. Eighteen patients treated for FAI were also interviewed, the majority of whom felt that surgery and conservative care were acceptable treatments. Surgery was viewed by patients as a 'definitive solution'. Patients were motivated to participate in research but were uncomfortable about randomization. Randomization was more acceptable if the alternative was available at the end of the trial. In the pilot phase, 151 patients were assessed for eligibility. Sixty were eligible and invited to take part in the pilot RCT; 42 consented to randomization. Follow-up was 100% at 12 months. Assessments of treatment fidelity were satisfactory. An RCT to compare arthroscopic hip surgery with conservative care in patients with FAI is challenging but feasible. Recruitment has started for a full RCT.

Protocol for a multicentre, parallel-arm, 12-month, randomised, controlled trial of arthroscopic surgery versus conservative care for femoroacetabular impingement syndrome (FASHIoN).

INTRODUCTION: Femoroacetabular impingement (FAI) syndrome is a recognised cause of young adult hip pain. There has been a large increase in the number of patients undergoing arthroscopic surgery for FAI; however, a recent Cochrane review highlighted that there are no randomised controlled trials (RCTs) evaluating treatment effectiveness. We aim to compare the clinical and cost-effectiveness of arthroscopic surgery versus best conservative care for patients with FAI syndrome. METHODS: We will conduct a multicentre, pragmatic, assessor-blinded, two parallel arm, RCT comparing arthroscopic surgery to physiotherapy-led best conservative care. 24 hospitals treating NHS patients will recruit 344 patients over a 26-month recruitment period. Symptomatic adults with radiographic signs of FAI morphology who are considered suitable for arthroscopic surgery by their surgeon will be eligible. Patients will be excluded if they have radiographic evidence of osteoarthritis, previous significant hip pathology or previous shape changing surgery. Participants will be allocated in a ratio of 1:1 to receive arthroscopic surgery or conservative care. Recruitment will be monitored and supported by qualitative intervention to optimise informed consent and recruitment. The primary outcome will be pain and function assessed by the international hip outcome tool 33 (iHOT-33) measured 1-year following randomisation. Secondary outcomes include general health (short form 12), quality of life (EQ5D-5L) and patient satisfaction. The primary analysis will compare change in pain and function (iHOT-33) at 12 months between the treatment groups, on an intention-to-treat basis, presented as the mean difference between the trial groups with 95% CIs. The study is funded by the Health Technology Assessment Programme (13/103/02). ETHICS AND DISSEMINATION: Ethical approval is granted by the Edgbaston Research Ethics committee (14/WM/0124). The results will be disseminated through open access peer-reviewed publications, including Health Technology Assessment, and presented at relevant conferences. TRIAL REGISTRATION NUMBER: ISRCTN64081839; Pre-results.

Protocol for a single-centre randomised controlled trial of multimodal periarticular anaesthetic infiltration versus single-agent femoral nerve blockade as analgesia for total knee arthroplasty: Perioperative Analgesia for Knee Arthroplasty (PAKA).

INTRODUCTION: Total knee arthroplasty (TKA) surgery causes postoperative pain. The use of perioperative injections around the knee containing local anaesthetic, opiates and non-steroidal anti-inflammatory drugs has increased in popularity to manage pain. Theoretical advantages include reduced requirements for analgesia and earlier mobilisation. We propose a single-centre randomised controlled trial of multimodal periarticular anaesthetic infiltration versus femoral nerve anaesthetic blockade as analgesia for TKA. The aim is to determine, in patients undergoing TKA, if there is a difference in patient-reported pain scores on the visual analogue scale (VAS) prior to physiotherapy on day 1 postoperatively between treatment groups. METHODS AND ANALYSIS: Patients undergoing a primary unilateral TKA at University Hospitals Coventry and Warwickshire Hospitals will be assessed for eligibility. A total of 264 patients will provide 90% power to detect a difference of 12 mm on the VAS on day 1 postoperatively at the 5% level. The trial will use 1:1 randomisation, stratified by mode of anaesthetic. Primary outcome measure will be the VAS for pain prior to physiotherapy on day 1. Secondary outcome measures include VAS on day 2, total use of opiate analgesia up to 48 h, ordinal pain scores up to 40 min after surgery, independent functional knee physiotherapist assessment on days 1 and 2. Oxford knee Scores (OKS), EuroQol (EQ-5D) and Douleur Neuropathic Pain Scores (DN2) will be recorded at baseline, 6 weeks and 12 months. Adverse events will be recorded up to 12 months. Analysis will investigate differences in VAS on day 1 between the two treatment groups on an intention-to-treat basis. Tests will be two-sided and considered to provide evidence for a significant difference if p values are less than 0.05. ETHICS AND DISSEMINATION: NRES Committee West Midlands, 23 September 2013 (ref: 13/WM/0316). The results will be disseminated via peer-reviewed publications and conference presentations. TRIAL REGISTRATION NUMBERS: ISRCTN 60611146 and EUDRACT Number 2013-002439-10 (protocol code number PAKA-33601-AS117013); Pre-results.

Effect of peripheral nerve injury on receptive fields of cells in the cat spinal cord.

When the sciatic and saphenous nerves are cut and ligated in adult cats, the immediate effect is the production of a completely anesthetic foot and a region in medial lumbar dorsal horn where almost all cells have lost their natural receptive fields (RFs). Beginning at about 1 week and maturing by 4 weeks, some 40% of cells in the medial dorsal horn gain a novel RF on proximal skin, that is, upper and lower leg, thigh, lower back, or perineum. This new RF is supplied by intact proximal nerves and not by sciatic and saphenous nerve fibers that sprouted in the periphery. During the period of switching of RFs from distal to proximal skin there was no gross atrophy of dorsal horn grey matter and no Fink-Heimer stainable degeneration of central arbors and terminals of peripherally axotomized afferents. In intact animals medial dorsal horn cells showed no sign of response to mechanical stimulation of proximal skin. RFs of some of the cells had spontaneous variations in size and sensitivity, but these were not nearly sufficient to explain the large shifts observed after chronic nerve section. Tetanic electrical stimulation of skin or peripheral nerves often caused RFs to shrink, but never to expand. Although natural stimuli of proximal skin would not excite medial dorsal horn cells in intact or acutely deafferented animals, it was found that electrical stimulation of proximal nerves did excite many of these cells, often at short latencies. In the discussion we justify our working hypothesis that the appearance of novel RFs is due to the strengthening or unmasking of normally present but ineffective afferent terminals, rather than to long-distance sprouting of new afferent arbors within the spinal cord.

A system of rat spinal cord lamina 1 cells projecting through the contralateral dorsolateral funiculus.

The aim of these experiments was to sample the properties of lamina I neurones with long ascending projections. Recordings have been made from 136 units at the L4/5 level, with ascending axons reaching C2. More than 80% of the units projected via the contralateral dorsolateral white matter and only 10% via the contralateral ventral quadrant. None projected via the dorsal columns. Receptive fields were typically 1-2 cm2 and although a substantial number of units responded to a limited range of intense stimuli, a greater number of units were fired by both low- and high-threshold stimulation. In contrast to cells of deeper laminae, the majority of units were excited following activation of descending pathways in the dorsolateral funiculus. The functional role of these units is not obvious, but the location of the ascending projection and the influence of descending pathways does not support the notion that the output of lamina 1 constitutes a simple "pain pathway."

Physiological evidence for branching of peripheral unmyelinated sensory afferent fibers in the rat.

Single unmyelinated sensory afferent nerve fibers were recorded in dorsal root filaments in urethane-anesthetized or in decerebrate-spinal rats. The peripheral branch of these axons ran in the sural nerve where they were stimulated by tungsten microelectrodes. All action potentials showed the characteristics of single fiber responses with a fixed all or none shape and a fixed latency at a given stimulus strength. In all units, the action potential evoked from a proximal stimulus site collided with the action potential evoked from a distal stimulus site. Of the 44 single units isolated, 17 showed the expected small progressive decrease of latency of the recorded impulse as the stimulus strength at a fixed point on the sural nerve was progressively raised above threshold. However, in 27 units there was an abrupt jump decrease of latency as the stimulus rose above the threshold. The average size of this latency shortening was 2.2 msec, which occurred as the stimulus strength rose a mean 21% above threshold. As the stimulus rose above threshold, 7 fibers showed 3 different fixed latencies and 2 fibers showed 4 fixed latencies. In order to test the possibility that the peripheral nerve contained 2 branches of the same axon with one conducting slower than the other, the peripheral nerve was stimulated at progressively longer conduction distances. As predicted, the difference between the 2 fixed latencies became larger as the conduction distance increased. We discuss 6 possible explanations for the results and conclude they are consistent with the proposals that some fibers branch distal to the dorsal root ganglion and some branches do not establish a functional sensory ending in the periphery.

Two modes of cutaneous reinnervation following peripheral nerve injury.

The return of sensation to the foot following sciatic nerve crush injury was analyzed behaviorally and electrophysiologically in the rat. Functional recovery begins within four days. Its early phase is accounted for by expansion of the functional distribution of intact neighboring fibers of the saphenous n. It occurs even if the sciatic n. is ligated, and it disappears with section of the saphenous n. Accompanying this functional expansion we began to encounter in electrophysiological recordings from the saphenous n., fibers with unusually large receptive fields (RF's) extending onto the plantar surface of the foot, well beyond their limits in intact rats. All of the expanded RF's were high threshold mechanoreceptors. On about the twentieth day after crushing, the regenerating sciatic n. began to make a functional contribution. This was seen by return of sensation to zones not invaded by the saphenous n. and by the onset of sensation in rats in which the saphenous n. had previously been ligated. With return of the sciatic n. the expanded distribution of the saphenous n. went back to its original boundaries. Correspondingly, we could no longer find expanded saphenous n. RF's. We conclude that cutaneous reinnervation begins with the collateral expansion of high threshold afferents from intact neighboring nerves. This alien innervation is later replaced upon regeneration of the original nerve.

Long ascending projections to the midbrain from cells of lamina I and nucleus of the dorsolateral funiculus of the rat spinal cord.

Small volumes (5-40 nl) of an aqueous solution of wheat-germ-agglutinin-conjugated horseradish peroxidase (WGA-HRP) were injected unilaterally into midbrain structures of 18 adult, albino rats. In 17 of these preparations cells of many types were found to be retrogradely labeled in cervical and lumbar spinal cord segments. The data reported here concern the number and location of labeled cells from injection sites in the midbrain that affected two distinct cell populations: neurons within the marginal layer (lamina I cells) and neurons of the nucleus of the dorsolateral funiculus (NDLF cells). In ten of the preparations, only nine of which are reported in detail here, a total of 1,831 labeled lamina I cells were identified. In the lumbar enlargement they reached a density of more than 60 cells/mm. Of these, 85% projected to medial portions of the caudal, contralateral midbrain. Injection sites that were centered in the caudal periaqueductal gray (PAG) and/or in the immediately adjacent region of nucleus cuneiformis labeled the largest numbers of lamina I cells. Cells of the NDLF were retrogradely labeled in all preparations in which lamina I cells were labeled but they were also observed in five cases in which lamina I cells were not labeled. A total of 1,914 NDLF cells were labeled from all injection sites. These cells were found to have essentially a bilateral distribution with 57% of the cells located in the contralateral DLF. Although there is substantial overlap between the terminal fields of lamina I and NDLF cells within the midbrain, NDLF cells had a more diffuse target area encompassing the reticular core of the midbrain and PAG, bilaterally, while the target area for lamina I cells was comparatively discrete, being largely restricted to the more medially situated midbrain structures, contralaterally. Whether the terminations of lamina I cells in and near the PAG are from collaterals of spinothalamic neurons originating in lamina I, or a subclass of lamina I neurons that project exclusively to the midbrain, is not known. It is significant, however, that lamina I cells, known to be activated by noxious stimuli to the skin, should project to a region of the brain stem from which analgesia can be produced by electrical stimulation or by local application of opiates.

The distribution of nine peptides in rat spinal cord with special emphasis on the substantia gelatinosa and on the area around the central canal (lamina X).

The comparative distribution of nine peptides was examined in the L4 segment of the rat cord using the peroxidase antiperoxidase technique. The peptides examined were substance P, neurotensin, cholecystokinin, methionine-enkephalin, oxytocin, neurophysin, adrenocorticotrophin, thyrotropin releasing hormone, and vasoactive intestinal polypeptide. No transport blocking agents were used and in spite of this cell bodies containing substance P, neurotensin, cholecystokinin, and methionine-enkephalin were observed. All peptides except for thyrotropin releasing hormone were observed in fibers in laminae I and II. All peptides were present in the area around the central canal, lamina X. Each peptide had its own characteristic distribution within fibers in the gray and white matter.

The effects of capsaicin applied to peripheral nerves on responses of a group of lamina I cells in adult rats.

In adult rats, the sciatic and saphenous nerves on one side were treated topically with capsaicin. The capsaicin treatment had the effect of increasing the latency for withdrawal of the foot from hot water; 11-22 days later, the animals were decerebrated, and cells in the superficial dorsal horn of the lumbar cord with axons projecting in the contralateral dorsolateral funiculus (DLF) were examined electrophysiologically on the treated and untreated sides of the cord. HRP was applied to cut axons of the DLF at C4, in other rats, and retrograde labelling of cells in the lumbar cord indicated that most or all of the recordings in the capsaicin-treated animals were likely to originate from lamina 1. The dorsal horn cells, with receptive fields on the foot, showed decreased responses to electrically evoked afferent impulses in C fibres and grossly altered receptive fields. After capsaicin treatment, the proportion of cells responding to C afferents fell from 83% to 14%. The proportion responding only to C afferents and not to A afferents fell from 9% to 0%. The receptive fields (RFs) of these cells showed two gross abnormalities; 32% of the cells on the treated side had no apparent RF or an ill-defined, intermittent RF, whereas such cells were rare on the untreated side or in intact animals. By contrast 49% of the cells had grossly expanded RFs with an average area of 430 mm2 against the normal average size of 130 mm2.(ABSTRACT TRUNCATED AT 250 WORDS)

Phantom limbs and related phenomena in recent traumatic amputations.

Seventy-three soldiers who had traumatic amputations were examined from 1 to 6 months after limb loss. All experienced phantom limb sensations and 67 percent experienced phantom limb pains, usually transient. Stump pain occurred in 43 percent and was associated with phantom pain in 54 percent of these. Of the 23 percent of the entire group who had evident stump pathology, 33 percent had phantom pains only, 20 percent had stump pains only, 40 percent had both, and 7 percent were pain-free. All stump ends exhibited an area of hyperpathia with hypoesthesia. Phantom pain probably results from peripheral or spinal cord mechanisms, or both, rather then from more rostral mechanisms.