Patient adherence to physical activity advice (PAPA) in patients with low back pain: Study protocol for a multicentre randomized controlled trial.

BACKGROUND: It seems that nonspecific low back pain (NSLBP) cannot be successfully treated with a single intervention of any kind. However, a positive effect of an active lifestyle including physical activities in NSLBP is reported on pain and disability. Advising regular physical activity is one of the mainstays in physical therapy treatment, appealing to patients' adherence. Many patients with low back pain do not seem to adhere to their physiotherapist's advice. In this study, the influence of social support on adherence to an activity advice will be investigated. OBJECTIVE: Objective of the study is to investigate if patients with low back pain randomised to receive social support adhere better to an activity advice than patients randomised to the control group. METHODS: In a randomized controlled clinical trial, in private physiotherapy practices in the Netherlands, patients ≥18 years presenting with at least a second episode of nonspecific low back pain will be randomized over two groups: activity advice and social support as an add-on to usual care versus usual care alone. The primary outcome measure is adherence to an activity advice measured by an activity monitor at 1, 6 and 12 weeks. All other objectives will be measured by questionnaires. DISCUSSION: This project is the first comprehensive research project to assess whether social support influences adherence to an activity advice outside the clinical setting without supervision of a healthcare provider. Where evidence of influence on social support is lacking, findings may have implications for the management of patients with low back pain. In addition, findings may enable physiotherapists to predict in which patients with low back pain an activity advice with social support makes sense. CLINICALTRIAL: GOV: NCT02996955.

Responsiveness and disease specificity of the Western Ontario Rotator Cuff index.

The goal of this study was to determine the disease specificity and responsiveness of the Western Ontario Rotator Cuff Index (WORC). Responsiveness, two cut-off points of the minimal important change, the area under the curve, standard error of measurement, the minimal detectable change and the standardized response mean were determined. Patients undergoing a rotator cuff repair need to improve more than 35 points to be considered clinical importantly improved. The WORC is disease specific and has a high responsiveness in patients undergoing rotator cuff repair and patients with disease of the rotator cuff without rotator cuff tears.

Pilot Study of Sequence of Segmental Contributions in the Lower Cervical Spine During Active Extension and Flexion: Healthy Controls Versus Cervical Degenerative Disc Disease Patients.

STUDY DESIGN: A retrospective study in which, first, a definition of normal movement in the cervical spine is formulated. Second, use of this definition in differentiating between normal and abnormal movement of the cervical spine is evaluated. OBJECTIVE: To formulate a clear definition of the normal sequence of segmental contributions in the cervical spine during flexion/extension, and to evaluate the sensitivity, specificity, and reliability of sequence of segmental contributions analysis in differentiating between normal and abnormal movement of the cervical spine in healthy controls and patients with cervical degenerative disc disease (CDDD). SUMMARY OF BACKGROUND DATA: To study mobility before and after cervical arthroplasty, segmental range of motion (sROM) is most commonly used. Analysis of sequence of segmental contributions during flexion and/or extension might be more suitable. METHODS: The definition was formulated by analyzing flexion cinematographic recordings (FCRs) and extension cinematographic recordings (ECRs) in healthy controls. Sequences in ECRs were more consistent than in FCRs and were therefore used to define "normal" motion. Five blinded spine surgeons scored randomized graphs from ECRs in 20 healthy controls and 10 preoperative CDDD patients, using this definition, at three time points. Sensitivity, specificity, and reliability were calculated. RESULTS: Reliability of scoring as normal or abnormal is high (Fleiss kappa of 0.80-0.84, 95% confidence interval, CI: 0.66-0.98), sensitivity and specificity are also high, with an average sensitivity of 90% (95% CI: 78.4-99.8%), and an average specificity of 85% (95% CI: 72.9-96.4%). CONCLUSION: This is the first described method that can reliably differentiate between normal or abnormal movement of the cervical spine in an individual subject. This enables an observer to determine if the normal sequence is restored after arthroplasty. In contrast to the given method, sROMs are not able to distinguish between healthy controls and CDDD patients. LEVEL OF EVIDENCE: 2.

Cervical spine kinematics after anterior cervical discectomy with or without implantation of a mobile cervical disc prosthesis; an RCT.

BACKGROUND: When surgically treating cervical degenerative disc disease, the most commonly performed procedure is anterior cervical discectomy. This procedure is performed with, or without fusion promoting methods. For both options the rate of fusion is high and there is much debate whether fusion of the treated segment is a contributing factor to accelerated degeneration of adjacent motion segments. In an effort to prevent degeneration of adjacent segments (ASDeg) due to loss of mobility at the operated level, cervical disc arthroplasty (CDA) was introduced. To evaluate the effectiveness of CDA in preventing ASDeg long term studies are necessary. However, prevention of ASDeg is based on the premise that mobile disc prostheses preserve cervical spine motion in a physiological way. In this article the authors describe a short term protocol for a study that aims to investigate whether CDA reaches the intended goal: restoration or preservation of physiological cervical spine motion. To this end, a technique is used to establish the sequence of contributions of cervical motion segments to flexion/extension of the spine. METHODS: 24 subjects between 18 and 55 years old, with radicular symptoms due to a herniated disc between C5 and C7, refractory to conservative therapy are randomized to simple discectomy, or CDA. These groups are preceded by a pilot group of three subjects receiving CDA. Fluoroscopic flexion-extension recordings are acquired preoperatively, and at three and 12 months postoperative. At these same time points, patient reported outcomes are collected, and a neurological examination is performed by and independent physician. DISCUSSION: Studies investigating arthroplasty determine mobility by measuring segmental range of motion (sROM), which gives no information other than presence, and quantity, of mobility. SROM suffer from high variability. The authors therefore chose to use a method previously used in healthy controls, to describe the dynamic process of cervical spine motion in more detail. Determining cervical spine motion patterns has been reported to be more consistent than sROM. If a physiological motion pattern is absent after surgery in the CDA group, prevention of future ASDeg is less likely. Radiological outcomes will be correlated to clinical outcomes. TRIAL REGISTRATION: NCT00868335.

The conceptually equivalent Dutch version of the Western Ontario Rotator Cuff Index (WORC)©.

BACKGROUND: The WORC is a quality of life questionnaire designed for patients with disorders of the rotator cuff, originally developed in English. The purpose of this study was to cross-culturally adapt the WORC for use in the Dutch population and to evaluate reliability, agreement and floor and ceiling effects of this Dutch version in a population of patients with rotator cuff disease. METHODS: Reliability was tested by measuring the Cronbach's alpha for internal consistency and intraclass correlation coefficients (ICC) for test-retest reliability. Agreement was measured using the Standard Error of Measurement (SEM(agreement)); and the smallest detectable change (SDC) was calculated based on the SEM. Pearson Correlations Coefficients were used to comparing the WORC with the RAND-36, the Constant Score and 11-point shoulder hindrance scale. RESULTS: Fifty-seven patients entered into this study of whom 50 were available for test-retest validation. The internal consistency of the Dutch WORC tested by Cronbach's alpha was 0.95 for the total questionnaire. The ICC for the WORC is 0.91 with a 95% confidence interval of 0.85-0.95. Standard Error of Measurement was 6.0 points with a Smallest Detectable Change of 16.7 points on a 0-100 scale. Pearson Correlations Coefficients showed a significant positive correlation between the Dutch WORC and Constant Score (r = 0.60) and a strong reversed correlation with the shoulder hindrance scale (r = -0.75). CONCLUSION: The Dutch WORC seems to be a reliable health-related quality of life questionnaire for patients with rotator cuff disorders. TRIAL REGISTRATION: NCT01532492.

Arthroplasty versus fusion in single-level cervical degenerative disc disease: a Cochrane review.

STUDY DESIGN: A systematic review of randomized controlled trials (RCTs). OBJECTIVE: To assess the effects of arthroplasty versus fusion in the treatment of radiculopathy or myelopathy, or both, due to single-level cervical degenerative disc disease. SUMMARY OF BACKGROUND DATA: There is ongoing debate about whether fusion or arthroplasty is superior in the treatment of single-level cervical degenerative disc disease. Mainly because the intended advantage of arthroplasty compared with fusion, prevention of symptoms due to adjacent segment degeneration in the long term, is not confirmed yet. Until sufficient long-term results become available, it is important to know whether results of 1 of the 2 treatments are superior to the other in the first 1 to 2 years. METHODS: We searched electronic databases for randomized controlled trials. We included randomized controlled trials that directly compared any type of cervical fusion with any type of cervical arthroplasty, with at least 1 year of follow-up. Study selection was performed independently by 3 review authors, and "risk of bias" assessment and data extraction were independently performed by 2 review authors. In case of missing data, we contacted the study authors or the study sponsor. We assessed the quality of evidence. RESULTS: Nine studies (2400 participants) were included in this review; 5 of these studies had a low risk of bias. Results for the arthroplasty group were better than the fusion group for all primary comparisons, often statistically significant. For none of the primary outcomes was a clinically relevant difference in effect size shown. Quality of the evidence was low to moderate. CONCLUSION: There is low to moderate quality evidence that results are consistently in favor of arthroplasty, often statistically significant. However, differences in effect size were invariably small and not clinically relevant for all primary outcomes. LEVEL OF EVIDENCE: 1.

Arthroplasty versus fusion in single-level cervical degenerative disc disease.

BACKGROUND: There is ongoing debate about whether fusion or arthroplasty is superior in the treatment of single level cervical degenerative disc disease. Mainly because the intended advantage of arthroplasty over fusion, that is, the prevention of symptoms due to adjacent segment degeneration in the long term, is not confirmed yet. Until sufficient long-term results become available, it is important to know whether results of one of the two treatments are superior to the other in the first one to two years. OBJECTIVES: To assess the effects of arthroplasty versus fusion for radiculopathy or myelopathy, or both due to single level cervical degenerative disc disease. SEARCH METHODS: We searched the following databases for randomised controlled trials (RCTs): CENTRAL (The Cochrane Library 2011, Issue 2), MEDLINE, EMBASE, and EBMR. Additionally, we searched the System for Information on Grey Literature (SIGLE), subheading Biological and Medical Sciences, the US Food and Drug Administration (FDA) database on medical devices, and Clinicaltrials.gov to identify trials in progress. We also screened the reference list of all selected papers. Date of search: 25 May 2011. SELECTION CRITERIA: We included RCTs that directly compared any type of cervical fusion with any type of arthroplasty, with at least one year of follow-up. Primary outcomes were arm pain, neck pain, neck-related functional status, patient satisfaction, neurological outcome, and global health status. Secondary outcomes were the presence of (radiological) fusion, revision surgery at the treated level, secondary surgery on adjacent levels, segmental mobility of treated and adjacent levels, and work status. DATA COLLECTION AND ANALYSIS: Study selection was performed independently by three review authors, and 'Risk of bias' assessment and data extraction were performed by two review authors. In case of missing data or insufficient information for a judgement about risk of bias, we tried to contact the study authors or the study sponsor. The data were entered into RevMan by one review author and subsequently checked by a second review author. We assessed the quality of evidence using GRADE. We analysed heterogeneity and performed sensitivity analyses for the pooled analyses. MAIN RESULTS: We included nine studies (2400 participants), five of which had a low risk of bias. Eight of these studies were industry sponsored. The most important results showed low-quality evidence for a small but significant difference in alleviation of arm pain at one to two years in favour of arthroplasty (mean difference (MD) -1.54; 95% confidence interval (CI) -2.86 to -0.22; 100-point scale). A small study effect could not be ruled out for this outcome in the sensitivity analyses. This means that smaller studies (or small published subsets of larger studies) showed larger differences for this outcome, which may indicate publication bias. Also, moderate-quality evidence showed a small difference in neck-related functional status at one to two years in favour of arthroplasty (MD -2.79; 95% CI -4.73 to -0.85; 100-point scale) and a small difference in neurological outcome in favour of arthroplasty (risk ratio (RR) 1.05; 95% CI 1.01 to 1.09). These two outcomes were robust to sensitivity analyses. For none of the primary outcomes, was a clinically relevant difference shown. Additionally, there was high-quality evidence for a large, statistically significant difference in segmental mobility at one to two years (measured as degrees segmental range of motion) at the treated level (MD 6.90; 95% CI 5.45 to 8.35). There was low-quality evidence that there was no statistically significant difference in secondary surgery at the adjacent levels at one to two years (RR 0.60; 95% CI 0.35 to 1.02). The latter was not robust to sensitivity analyses. AUTHORS' CONCLUSIONS: There was a tendency for clinical results to be in favour of arthroplasty; often these were statistically significant. However, differences in effect size were invariably small and not clinically relevant for all primary outcomes. Significance was often gained or lost in the varying sensitivity analyses, probably owing to the relatively small number of studies, in combination with the small differences that were found. Given the fact that all of the included studies were not blinded, this could be due to patient or carer expectations. However, at this time both treatments can be seen as valid options with respect to results at a maximum of one to two years. Given the current absence of truly long-term results, use of these mobile disc prostheses should still be limited to clinical trials. There was high-quality evidence that the goal of preservation of segmental mobility in arthroplasty was met. A statistically significant effect on the incidence of secondary symptoms at adjacent levels, the primary goal of arthroplasty over fusion, was not found at one to two years. If there was a protective effect, this should become clearer over time. A future update, when studies with 'truly long-term' results (five years or more) become available, should focus on this issue.

Validation of the Western Ontario Rotator Cuff index in patients with arthroscopic rotator cuff repair: a study protocol.

BACKGROUND: Arthroscopic rotator cuff repair is described as being a successful procedure. These results are often derived from clinical general shoulder examinations, which are then classified as 'excellent', 'good', 'fair' or 'poor'. However, the cut-off points for these classifications vary and sometimes modified scores are used.Arthroscopic rotator cuff repair is performed to improve quality of life. Therefore, disease specific health-related quality of life patient-administered questionnaires are needed. The WORC is a quality of life questionnaire designed for patients with disorders of the rotator cuff. The score is validated for rotator cuff disease, but not for rotator cuff repair specifically. The aim of this study is to investigate reliability, validity and responsiveness of WORC in patients undergoing arthroscopic rotator cuff repair. METHODS/DESIGN: An approved translation of the WORC into Dutch is used. In this prospective study three groups of patients are used: 1. Arthroscopic rotator cuff repair; 2. Disorders of the rotator cuff without rupture; 3. Shoulder instability. The WORC, SF-36 and the Constant Score are obtained twice before therapy is started to measure reliability and validity. Responsiveness is tested by obtaining the same tests after therapy.

Cervical vertebrae tracking in video-fluoroscopy using the normalized gradient field.

For patients with neck problems valuable functional and diagnostic information can be obtained from a fluoroscopy video of a flexion-extension movement of the cervical spine. In most cases physicians have to manually extract the vertebrae, making the analysis of these video sequences tedious and time consuming. In this paper we propose an automatic fast and precise method for tracking cervical vertebrae. Our method relies only on a rough selection of template areas of each vertebra in a single frame of the video sequence. Compared to existing automated methods, no contours need to be extracted and no vertebra segmentation is required. Tracking is done with a normalized gradient field, using only the gradient orientations as features. Experimental results show that the algorithm is robust and able to track the vertebrae accurately even if they are partially occluded or if a disc prosthesis is present.

Equivalent correction in scarf and chevron osteotomy in moderate and severe hallux valgus: a randomized controlled trial.

BACKGROUND: Chevron osteotomy is a widely accepted osteotomy for correction of hallux valgus.(18) Algorithms were developed to overcome the limitations of distal osteotomies. Scarf osteotomy has become popular as a versatile procedure that should be able to correct most cases of acquired hallux valgus. The purpose of this study was to evaluate whether patients with moderate or severe hallux valgus have better correction with a scarf osteotomy as compared to chevron osteotomy. MATERIALS AND METHODS: After informed consent, 136 feet in 115 patients were randomized to 66 scarf and 70 chevron osteotomies. Deformities of patients were classified as mild, moderate and severe according to IMA, and both groups were compared with independent t-tests. The results were measured using radiographic HVA, IMA and DMAA measurements. RESULTS: There were no statistical differences in HVA, IMA and DMAA between scarf and chevron osteotomy in mild to moderate hallux valgus. In severe hallux valgus, chevron osteotomy corrected HVA better than scarf osteotomy, although this group consisted of twelve patients only. Five patients in the chevron group and seven in the scarf group developed recurrent subluxation of the metatarsophalangeal joint. CONCLUSION: In patients with moderate and severe hallux valgus, the results of chevron osteotomy were at least as effective as a scarf osteotomy. Recurrent subluxation of the first metatatarsophalangeal joint was the main cause for insufficient correction. We favor the chevron osteotomy because it is less invasive, without sacrificing correction of HVA and IMA.

Test-retest reproducibility of elbow goniometric measurements in a rigid double-blinded protocol: intervals for distinguishing between measurement error and clinical change.

Increasingly, goniometry of elbow motion is used for qualification of research results. Expression of reliability is in parameters not suitable for comparison of results. We modified Bland and Altman's method, resulting in the smallest detectable differences (SDDs). Two raters measured elbow excursions in 42 individuals (144 ratings per test person) with an electronic digital inclinometer in a classical test-retest crossover study design. The SDDs were 0 +/- 4.2 degrees for active extension; 0 +/- 8.2 degrees for active flexion, both without upper arm fixation; 0 +/- 6.3 degrees for active extension; 0 +/- 5.7 degrees for active flexion; 0 +/- 7.4 degrees for passive flexion with upper arm fixation; 0 +/- 10.1 degrees for active flexion with upper arm retroflexion; and 0 +/- 8.5 degrees and 0 +/- 10.8 degrees for active and passive range of motion. Differences smaller than these SDDs found in clinical or research settings are attributable to measurement error and do not indicate improvement.

Digital goniometric measurement of knee joint motion. Evaluation of usefulness for research settings and clinical practice.

An accurate and reproducible measurement method for joint motion is essential for classification of success or failure in therapeutic intervention. Digital goniometry is increasingly used as a method of classification for knee joint excursion. The reliability of goniometry however remains debatable. Aim of the study was to determine both intra- and inter-rater reproducibility in degrees, with an electronic digital inclinometer (EDI 320) for active and passive maximum flexion and active maximum extension of the knee joint and to determine the reproducibility of active and passive range of motion. A classical crossover design, with strict measurement protocol was used. Two raters measured 72 knee motions each, in 42 healthy subjects in four sessions. The smallest detectable difference (SDD) was calculated by using adjusted Bland and Altman plots for each knee excursion. No differences in joint excursions between the sexes were found. Passive maximum flexion showed larger excursions than active maximum flexion with additional higher levels of reproducibility. SDDs for inter-rater comparisons yielded: 0+/-3.9 degrees for active maximum extension, 0+/-7.4 degrees for active maximum flexion, 0+/-6.4 degrees for passive maximum flexion, 0+/-7.6 degrees for AROM and 0+/-5.4 degrees for PROM. Intra-rater SDDs showed increased reproducibility by 0.4-1.9 degrees. We conclude that interpretation of knee joint excursions in clinical settings is with these SDDs. Clinical and statistical differences in research settings within these SDDs are not a true difference but should be attributed to measurement error.

Stapedius muscle fiber characterization during postnatal development in the rat.

The stapedius muscle (SM) is reported to prevent cochlear damage by noise. Functional demands are then the ability of fast contraction with long endurance. At the end of the third postnatal week, the middle ear of the rat is completely pneumatized and according to electrophysiological data, the auditory function starts to match the adult. We investigated the developmental changes in myosin composition of SM fibres using consecutive complete SM cross-sections (taken from rats on post natal day (PND) 7, 14, 16, 21, 28, 42 and 84) which were processed by enzymehistochemistry to determine acid/alkali lability of myofibrillar adenosine triphosphatase (mATPase) and by immunohistochemistry using myosin heavy chain (MHC) antibodies (mAb). Fibres were assigned to mATPase type I, IIA, IIB, IIX or 'Miscellaneous' categories. Per mATPase category, the fibres were attributed to groups with specific MHC isoform compositions. Neonatal MHC expression could not be documented with the mAb used. However, embryonal (Emb) MHC was expressed at PND 7, very little at PND 14; at later PND fibres did not show Emb MHC. In general, the mATPase-based classification did not show large alterations after PND 21. Expression of MHC IIB, which was present in almost 50% of the fibres at PND 7 and 14, diminished to 3% at PND 84. A decrease in number of fibres expressing more than one MHC isoform was found. These results show that the SM is a precociously developing muscle compared to limb muscles and even to the diaphragm. Moreover, it is shown that the expression of the adult MHC isoform phenotype coincides with the onset of auditory function in the third postnatal week.

Reproducibility of cervical range of motion in patients with neck pain.

BACKGROUND: Reproducibility measurements of the range of motion are an important prerequisite for the interpretation of study results. The aim of the study is to assess the intra-rater and inter-rater reproducibility of the measurement of active Range of Motion (ROM) in patients with neck pain using the Cybex Electronic Digital Inclinometer-320 (EDI-320). METHODS: In an outpatient clinic in a primary care setting 32 patients with at least 2 weeks of pain and/or stiffness in the neck were randomly assessed, in a test- retest design with blinded raters using a standardized measurement protocol. Cervical flexion-extension, lateral flexion and rotation were assessed. RESULTS: Reliability expressed by the Intraclass Correlation Coefficient (ICC) was 0.93 (lateral flexion) or higher for intra-rater reliability and 0.89 (lateral flexion) or higher for inter-rater reliability. The 95% limits of agreement for intra-rater agreement, expressing the range of the differences between two ratings were -2.5 +/- 11.1 degrees for flexion-extension, -0.1 +/- 10.4 degrees for lateral flexion and -5.9 +/- 13.5 degrees for rotation. For inter-rater agreement the limits of agreement were 3.3 +/- 17.0 degrees for flexion-extension, 0.5 +/- 17.0 degrees for lateral flexion and -1.3 +/- 24.6 degrees for rotation. CONCLUSION: In general, the intra-rater reproducibility and the inter-rater reproducibility were good. We recommend to compare the reproducibility and clinical applicability of the EDI-320 inclinometer with other cervical ROM measures in symptomatic patients.

Effect of tube angulation on the measurement of intermetatarsal angles.

We systematically investigated the effect of tube angulation on angular distortion of the anteroposterior radiograph of the foot. Three-dimensional data from the metatarsals originating from computed tomographic scans of ten healthy volunteers were projected onto the supporting surface at various tube angulations to simulate radiography. The distortion of the intermetatarsal angles decreased from 1.2 degrees to 3.5 degrees at 20 degrees tube angulation to 0.4 degrees to 2.7 degrees at 0 degrees tube angulation. The relatively small improvement in angular measurement using 0 degrees instead of 15 degrees tube angulation would not outweigh the adverse effects of changing the standard radiographic technique. Physician awareness of this source of error when planning surgical therapy seems more important.

The intermetatarsal and metatarsal declination angles: geometry as a source of error.

BACKGROUND: The measurements on radiographs of the foot are believed to give an objective impression of foot deformities. In patient management, the outcome of these measurements is one of the factors that the physician takes into consideration. In fact, the radiograph is a projection of three-dimensional structures and is as such liable to a certain amount of distortion. To our knowledge this distortion has not been quantified, although it seems important for the interpretation of the measurements. METHODS: First, mathematical models based on the geometry of standard anteroposterior and lateral radiographs were constructed and analyzed. Then, we simulated radiography with these models on three-dimensional data of metatarsals originating from CT scans of 10 normal volunteers. RESULTS: The distortion of the declination angles of the metatarsals was practically negligible. The intermetatarsal angles were distorted up to 5.4 degrees. The measured angles underestimated the three-dimensional angles. CONCLUSIONS: In interpreting the measurements of the metatarsal declination angles, distortion was not a factor. For intermetatarsal angles variability of distortion was only about one third of the reported interobserver variability, but it may have cumulative effects on the error of measured intermetatarsal angles. Moreover, the theoretical models predicted larger distortions in patients with deformities. In interpretation of angular measurements the physician should be aware of these pitfalls.

Do students have sufficient knowledge of clinical anatomy?

INTRODUCTION: Comparisons of anatomy knowledge levels of students from various curricula show either no differences or small differences to the detriment of innovative schools. To pass judgement on the general level of students' anatomy knowledge, we need an absolute standard. The purpose of this study was to compare students' levels of anatomy knowledge as measured by a case-based anatomy test with standards set by different groups of experts. METHODS: A modified Angoff procedure was used to establish an absolute standard against which the students' results could be evaluated. Four panels of 9 anatomists, 7 clinicians, 9 recent graduates and 9 Year 4 students, respectively, judged 107 items of an anatomy test. The students' results on these items were compared with the standards obtained by the panels. RESULTS: If the standard established by the panel of Year 4 students was used, 64% of the students would fail the test. The standards established by the anatomists, clinicians and recent graduates would yield failure rates of 42%, 58% and 26%, respectively. CONCLUSION: According to the panels' standards, many students did not know enough about anatomy. The high expectations that the Year 4 students appeared to have of their peers may contribute to students' uncertainty about their level of anatomy knowledge.

Plantar pressure and sole thickness of the forefoot.

BACKGROUND: Based on earlier observations that the forefoot bears the highest plantar pressure at its center, the existence of a functional distal transverse arch in normal feet was denied, and plantar pressure was defined as merely the outcome of loading, surface area, and soft tissue. Although plantar pressure drives the changes in the foot, neither the position nor the behavior of the metatarsals during loading can be derived from plantar pressure alone. In light of this, our goal was to describe the changes in thickness in the sole and the corresponding plantar pressure during loading of the foot. METHODS: We used CT to image the foot of 10 subjects in four postures that were chosen to imitate four phases in the walking cycle. Before imaging we also recorded the plantar pressure with a pressure measuring insole on which the subjects were standing. From the data, the minimal thickness of the sole and the corresponding plantar pressure were derived. RESULTS: With the exception of the sesamoids, the thickness of the sole under the bones of the forefoot increased from lateral to medial. This persisted in all postures. Our pressure readings matched previously reported distributions. CONCLUSIONS: Depending on the point of view concerning the sesamoids, the bony prominences were placed in a geometrical arch; but they did not form a functional arch. The soft tissue underneath the heads kept the metatarsals in place; the soft-tissue thickness reflected the principle of adequate cushioning.