Same-day discharge after laparoscopic hysterectomy for benign/premalignant disease: A multicentre randomised controlled trial.

OBJECTIVE: To evaluate whether physical function and quality of life was influenced by discharge on the same-day after a total laparoscopic hysterectomy. DESIGN: Multicentre non-inferiority randomised controlled trial. SETTING: Five teaching hospitals and two university hospitals in the Netherlands. POPULATION: Patients undergoing laparoscopic hysterectomy for benign or premalignant disease. METHODS: Following informed consent, participants were allocated 1:1 either to same-day discharge (SDD) or next-day discharge (NDD). MAIN OUTCOME MEASURES: The primary outcome was physical function at 7 days after surgery measured by the Patient Reported Outcomes Measurement Information System (PROMIS) Physical Function short Form 10A. Secondary outcomes were physical function and quality of life at 1 and 3 days and 6 weeks after surgery measured with PROMIS short Form 10A and the EuroQol questionnaire (EQ-5D-5L). RESULTS: Two hundred and five patients were included of whom 105 were allocated to SDD and 100 to NDD. Physical function 7 days after surgery was 35.95 in the SDD group and 35.63 in the control group (mean difference 0.32; 95% CI [0.07-0.57]). As the upper limit of the 95% CI does not exceed the non-inferiority margin of 4 points, non-inferiority of SDD could be demonstrated. No difference in physical function nor quality of life on Days 1 and 3 and 6 weeks could be found. CONCLUSION: This research demonstrates same-day discharge after laparoscopic hysterectomy is non-inferior to next day discharge in physical function 7 days after surgery.

Procedural sedation and analgesia versus general anesthesia for hysteroscopic myomectomy (PROSECCO trial): A multicenter randomized controlled trial.

BACKGROUND: Hysteroscopic resection is the first-choice treatment for symptomatic type 0 and 1 fibroids. Traditionally, this was performed under general anesthesia. Over the last decade, surgical procedures are increasingly being performed in an outpatient setting under procedural sedation and analgesia. However, studies evaluating safety and effectiveness of hysteroscopic myomectomy under procedural sedation are lacking. This study aims to investigate whether hysteroscopic myomectomy under procedural sedation and analgesia with propofol is noninferior to hysteroscopic myomectomy under general anesthesia. METHODS AND FINDINGS: This was a multicenter, randomized controlled noninferiority trial conducted in 14 university and teaching hospitals in the Netherlands between 2016 and 2021. Inclusion criteria were age ≥18 years, maximum number of 3 type 0 or 1 fibroids, maximum fibroid diameter 3.5 cm, American Society of Anesthesiologists class 1 or 2, and having sufficient knowledge of the Dutch or English language. Women with clotting disorders or with severe anemia (Hb < 5.0 mmol/L) were excluded. Women were randomized using block randomization with variable block sizes of 2, 4, and 6, between hysteroscopic myomectomy under procedural sedation and analgesia (PSA) with propofol or under general anesthesia (GA). Primary outcome was the percentage of complete resections, assessed on transvaginal ultrasonography 6 weeks postoperatively by a sonographer blinded for the treatment arm and surgical outcome. Secondary outcomes were the surgeon's judgment of completeness of procedure, menstrual blood loss, uterine fibroid related and general quality of life, pain, recovery, hospitalization, complications, and surgical reinterventions. Follow-up period was 1 year. The risk difference between both treatment arms was estimated, and a Farrington-Manning test was used to determine the p-value for noninferiority (noninferiority margin 7.5% of incomplete resections). Data were analyzed according to the intention-to-treat principle, including a per-protocol analysis for the primary outcome. A total of 209 women participated in the study and underwent hysteroscopic myomectomy with PSA (n = 106) or GA (n = 103). Mean age was 45.1 [SD 6.4] years in the PSA group versus 45.0 [7.7] years in the GA group. For 98/106 women in the PSA group and 89/103 women in the GA group, data were available for analysis of the primary outcome. Hysteroscopic resection was complete in 86/98 women (87.8%) in the PSA group and 79/89 women (88.8%) in the GA group (risk difference -1.01%; 95% confidence interval (CI) -10.36 to 8.34; noninferiority, P = 0.09). No serious anesthesiologic complications occurred, and conversion from PSA to GA was not required. During the follow-up period, 15 serious adverse events occurred (overnight admissions). All were unrelated to the intervention studied. Main limitations were the choice of primary outcome and the fact that our study proved to be underpowered. CONCLUSIONS: Noninferiority of PSA for completeness of resection was not shown, though there were no significant differences in clinical outcomes and quality of life. In this study, hysteroscopic myomectomy for type 0 and 1 fibroids with PSA compared to GA was safe and led to shorter hospitalization. These results can be used for counseling patients by gynecologists and anesthesiologists. Based on these findings, we suggest that hysteroscopic myomectomies can be performed under PSA in an outpatient setting. TRIAL REGISTRATION: The study was registered prospectively in the Dutch Trial Register (NTR 5357; registration date: 11 August 2015; Date of initial participant enrollment: 18 February 2016).

Restrictive versus liberal fluid administration strategy (REFILL study) in postpartum hemorrhage and its effects on thromboelastometry (ROTEM®) values: a randomized, controlled trial.

OBJECTIVE: Current obstetric guidelines for postpartum hemorrhage (PPH) vary in fluid resuscitation management. This study aimed to evaluate the effect of fluid management on coagulation parameters in early PPH. METHODS: We performed a multicenter, randomized trial. Women who had 500 mL of blood loss in the third stage of labor were randomized to receive a restrictive fluid administration strategy or a liberal fluid administration strategy. A rotational thromboelastometry panel was performed in 72 patients. We evaluated within-group and between-group differences in the EXTEM clotting time (CT), EXTEM amplitude at 10 minutes (A10), INTEM CT, and FIBTEM A10. We also evaluated the mean fibrinogen concentration, activated partial thromboplastin time, and partial thromboplastin time in the total study population (n = 249). RESULTS: There were no significant differences in hemostatic parameters between the groups after correction for baseline values. CONCLUSIONS: In women with PPH <1500 mL, there is no clinically relevant effect of a restrictive or liberal fluid administration strategy on thromboelastometric hemostatic and regular coagulation parameters.

Levonorgestrel-releasing intrauterine system versus endometrial ablation for heavy menstrual bleeding.

BACKGROUND: Heavy menstrual bleeding affects the physical functioning and social well-being of many women. The levonorgestrel-releasing intrauterine system and endometrial ablation are 2 frequently applied treatments in women with heavy menstrual bleeding. OBJECTIVE: This study aimed to compare the effectiveness of the levonorgestrel-releasing intrauterine system with endometrial ablation in women with heavy menstrual bleeding. STUDY DESIGN: This multicenter, randomized controlled, noninferiority trial was performed in 26 hospitals and in a network of general practices in the Netherlands. Women with heavy menstrual bleeding, aged 34 years and older, without a pregnancy wish or intracavitary pathology were randomly allocated to treatment with either the levonorgestrel-releasing intrauterine system (Mirena) or endometrial ablation, performed with a bipolar radiofrequency device (NovaSure). The primary outcome was blood loss at 24 months, measured with a Pictorial Blood Loss Assessment Chart score. Secondary outcomes included reintervention rates, patient satisfaction, quality of life, and sexual function. RESULTS: We registered 645 women as eligible, of whom 270 women provided informed consent. Of these, 132 women were allocated to the levonorgestrel-releasing intrauterine system (baseline Pictorial Blood Loss Assessment Chart score, 616) and 138 women to endometrial ablation (baseline Pictorial Blood Loss Assessment Chart score, 630). At 24 months, mean Pictorial Blood Loss Assessment Chart scores were 64.8 in the levonorgestrel-releasing intrauterine system group and 14.2 in the endometrial ablation group (difference, 50.5 points; 95% confidence interval, 4.3-96.7; noninferiority, P=.87 [25 Pictorial Blood Loss Assessment Chart point margin]). Compared with 14 women (10%) in the endometrial ablation group, 34 women (27%) underwent a surgical reintervention in the levonorgestrel-releasing intrauterine system group (relative risk, 2.64; 95% confidence interval, 1.49-4.68). There was no significant difference in patient satisfaction and quality of life between the groups. CONCLUSION: Both the levonorgestrel-releasing intrauterine system and endometrial ablation strategies lead to a large decrease in menstrual blood loss in women with heavy menstrual bleeding, with comparable quality of life scores after treatment. Nevertheless, there was a significant difference in menstrual blood loss in favor of endometrial ablation, and we could not demonstrate noninferiority of starting with the levonorgestrel-releasing intrauterine system. Women who start with the levonorgestrel-releasing intrauterine system, a reversible and less invasive treatment, are at an increased risk of needing additional treatment compared with women who start with endometrial ablation. The results of this study will enable physicians to provide women with heavy menstrual bleeding with the evidence to make a well-informed decision between the 2 treatments.

The (cost) effectiveness of procedural sedation and analgesia versus general anaesthesia for hysteroscopic myomectomy, a multicentre randomised controlled trial: PROSECCO trial, a study protocol.

BACKGROUND: In women with abnormal uterine bleeding, fibroids are a frequent finding. In case of heavy menstrual bleeding and presence of submucosal type 0-1 fibroids, hysteroscopic resection is the treatment of first choice, as removal of these fibroids is highly effective. Hysteroscopic myomectomy is currently usually performed in the operating theatre. A considerable reduction in costs and a higher patient satisfaction are expected when procedural sedation and analgesia with propofol (PSA) in an outpatient setting is applied. However, both safety and effectiveness - including the necessity for re-intervention due to incomplete resection - have not yet been evaluated. METHODS: This study is a multicentre randomised controlled trial with a non-inferiority design and will be performed in the Netherlands. Women > 18 years with a maximum of 3 symptomatic type 0 or 1 submucosal fibroids with a maximum diameter of 3.5 cm are eligible to participate in the trial. After informed consent, 205 women will be randomised to either hysteroscopic myomectomy using procedural sedation and analgesia with propofol in an outpatient setting or hysteroscopic myomectomy using general anaesthesia in a clinical setting in the operating theatre. Primary outcome will be the percentage of complete resections, based on transvaginal ultrasonography 6 weeks postoperatively. Secondary outcomes are cost effectiveness, menstrual blood loss (Pictorial blood assessment chart), quality of life, pain, return to daily activities/work, hospitalization, (post) operative complications and re-interventions. Women will be followed up to one year after hysteroscopic myomectomy. DISCUSSION: This study may demonstrate comparable effectiveness of hysteroscopic myomectomy under procedural sedation and analgesia versus general anaesthesia in a safe and patient friendly environment, whilst achieving a significant cost reduction. TRIAL REGISTRATION: Dutch trial register, number NTR5357 . Registered 11th of August 2015.

Levonorgestrel releasing intrauterine system (Mirena) versus endometrial ablation (Novasure) in women with heavy menstrual bleeding: a multicentre randomised controlled trial.

BACKGROUND: Heavy menstrual bleeding is an important health problem. Two frequently used therapies are the levonorgestrel intra-uterine system (LNG-IUS) and endometrial ablation. The LNG-IUS can be applied easily by the general practitioner, which saves costs, but has considerable failure rates. As an alternative, endometrial ablation is also very effective, but this treatment has to be performed by a gynaecologist. Due to lack of direct comparison of LNG-IUS with endometrial ablation, there is no evidence based preferred advice for the use of one of these treatment possibilities. METHOD/DESIGN: A multicenter randomised controlled trial, organised in a network infrastructure in the Netherlands in which general practitioners and gynaecologists collaborate. DISCUSSON: This study, considering both effectiveness and cost effectiveness of LNG-IUS versus endometrial ablation may well improve care for women with heavy menstrual bleeding. TRIAL REGISTRATION: Dutch trial register, number NTR2984.

The predictive value of first trimester fetal volume measurements, a prospective cohort study.

OBJECTIVES: To determine if fetal volume (FV) measurements with three-dimensional ultrasound in the first trimester of pregnancy can detect the fetus at risk for preterm birth and/or low birth weight. METHODS: In this prospective cohort study, 538 participants were included during the routine first trimester ultrasound examination. Volume measurements were performed with VOCAL (9°). Firstly, the relation between FV and gestational age for a set of participants with normal pregnancies (training set), was assessed using multiple linear regression analysis, which was then used to determine the expected normal values. Secondly, for a new set of participants with normal pregnancies and a set of participants with complicated pregnancies (preterm birth and/or low birth weight), i.e. the validation set, the observed fetal volumes (FVobserved) were compared with their expected normal values (FVexpected) and expressed as a percentage of the expected normal value. The difference in mean percentage was then assessed with independent-samples t-test. Finally, logistic regression analysis was applied to the validation set to analyze the ability to predict the pregnancy outcome with FV calculation. RESULTS: Linear regression analysis of FV as a predictor of preterm birth and/or low birth weight did not result in significant (p=0.630 and 0.290, respectively) or clinical relevant results (standardized effect sizes of 0.061 and 0.179, respectively). The predicting quality was also very low (AUC=0.508 and 0.545 respectively). CONCLUSIONS: Fetal volume measurements in the first trimester of pregnancy are not useful as a prognostic tool for predicting pregnancies of high risk for preterm birth or a low birth weight.

Fetal volume measurements with three dimensional ultrasound in the first trimester of pregnancy, related to pregnancy outcome, a prospective cohort study.

BACKGROUND: First trimester growth restriction is associated with an increased risk of adverse birth outcomes (preterm birth, low birth weight and small for gestational age at birth). The differences between normal and abnormal growth in early pregnancy are small if the fetal size is measured by the crown-rump-length. Three-dimensional ultrasound volume measurements might give more information about fetal development than two-dimensional ultrasound measurements. Detection of the fetus with a small fetal volume might result in earlier detection of high risk pregnancies and a better selection of high risk pregnancies. METHODS: A prospective cohort study, performed at the Máxima Medical Centre, in Eindhoven-Veldhoven, the Netherlands. During the routine first trimester scan with nuchal translucency measurement 500 fetal volumes will be obtained. The gestational age is based on the first day of the last menstrual period in a regular menstrual cycle and by the crown-rump-length. The acquired datasets are collected and stored on a hard disk for offline processing and volume calculation. The investigator who performs the volume measurements is blinded for the results of the first trimester scan. The manual mode will be used to outline the Region Of Interest, the fetal head and rump, in all cross sections. The fetal volumes are calculated with a rotational step of 9°.First, the relation between fetal volume and gestational age, for a set of participants with normal pregnancies (training set), will be assessed. This model will then be used to determine expected values of fetal volume for a normal pregnancy, which will be referred to as expected normal values. Secondly, for a new set of participants with normal pregnancies and a set of participants with complicated pregnancies (together defined as validation set), the observed fetal volumes (FV(observed)) are compared with their expected normal values (FV(expected)) and expressed as a percentage of the expected normal value. The mean difference in percentage error between the set of normal versus complicated pregnancies will then be compared using the independent-samples t-test. Finally, logistic regression analysis will be applied to the validation set of participants to analyze the possibility of predicting the pregnancy outcome after fetal volume calculation in the first trimester, using this percentage error. DISCUSSION: After this study it is clear whether FV measurement in the first trimester can detect high risk pregnancies. If it is possible to detect these pregnancies, more intensive follow up in these pregnancies might result in fewer complicated pregnancies and fewer fetal morbidities.

A new semi-automated method for fetal volume measurements with three-dimensional ultrasound: preliminary results.

OBJECTIVE: Complications in pregnancy are suggested to be the result of intrauterine conditions in the first trimester of pregnancy. Three-dimensional ultrasound volume measurements might give more information, compared with two-dimensional measurements. Commonly available methods for volume measurements are not suited for daily practice. This is a report of preliminary results of a promising, more practical semi-automated method for volume calculations with three-dimensional ultrasound. METHOD: Volume datasets of 16 objects (10.2-41.5 cm(3) ) were obtained. Euclidean shortening flow and Perona and Malik were used as image enhancement techniques. The image gradient was calculated. The points of interest were detected by the iso-intensity and the edge-detection technique. Volume measurements with Volume Computer-aided AnaLysis (VOCAL) are used as a reference. A volume dataset of a first trimester fetus was acquired to test this method in vivo. RESULTS: The mathematical calculations with iso-intensity (Perona and Malik: average= -1.57 cm(3) , SD=4.05; and Euclidean shortening flow: average= -1.38 cm(3) , SD=2.47) showed results comparable with the VOCAL method (average= +1.28 cm(3) , SD=2.07). We also succeeded in detecting all voxels in the whole contour of a 12-week fetus. CONCLUSION: Mathematical volume calculations are possible with the semi-automated method. We were able to apply this new method on a first trimester fetus. This new method is promising for future use in the daily practice.

Inter- and intra-observer variation of fetal volume measurements with three-dimensional ultrasound in the first trimester of pregnancy.

OBJECTIVES: To determine the inter- and intra-observer variation of volume calculations of human fetuses at a gestational age of 11(+0)-13(+6) weeks by three-dimensional ultrasound (3DUS). METHODS: 3DUS datasets were acquired during nuchal translucency measurements. The fetal volume (FV) was measured in 65 cases by two independent investigators. The Virtual Organ Computer aided AnaLysis (VOCAL™) imaging software was used to manually calculate the FV (rotational angle 9°). Inter- and intra-observer variation were assessed by Bland-Altman plots and intraclass correlation coefficients (ICC). RESULTS: Both inter- and intraobserver reproducibility were highly reliable as shown by the Bland-Altman plots and an ICC of respectively 0.934 and 0.994. CONCLUSION: FV calculation by 3DUS with VOCAL and a rotational angle of 9° is feasible and has a high inter- and intraobserver reliability in the first trimester of pregnancy.

Measuring the positional accuracy of computer assisted surgical tracking systems.

Computer Assisted Orthopaedic Surgery (CAOS) technology is constantly evolving with support from a growing number of clinical trials. In contrast, reports of technical accuracy are scarce, with there being no recognized guidelines for independent measurement of the basic static performance of computer assisted systems. To address this problem, a group of surgeons, academics and manufacturers involved in the field of CAOS collaborated with the American Society for Testing and Materials (ASTM) International and drafted a set of standards for measuring and reporting the technical performance of such systems. The aims of this study were to use these proposed guidelines in assessing the positional accuracy of both a commercially available and a novel tracking system. A standardized measurement object model based on the ASTM guidelines was designed and manufactured to provide an array of points in space. Both the Polaris camera with associated active infrared trackers and a novel system that used a small visible-light camera (MicronTracker) were evaluated by measuring distances and single point repeatability. For single point registration the measurements were obtained both manually and with the pointer rigidly clamped to eliminate human movement artifact. The novel system produced unacceptably large distance errors and was not evaluated beyond this stage. The commercial system was precise and its accuracy was well within the expected range. However, when the pointer was held manually, particularly by a novice user, the results were significantly less precise by a factor of almost ten. The ASTM guidelines offer a simple, standardized method for measuring positional accuracy and could be used to enable independent testing of tracking systems. The novel system demonstrated a high level of inaccuracy that made it inappropriate for clinical testing. The commercially available tracking system performed well within expected limits under optimal conditions, but revealed a surprising loss of accuracy when movement artifacts were introduced. Technical validation of systems may give the user community more confidence in CAOS systems as well as highlighting potential sources of point registration error.

Development and validation of an electrogoniometric wrist alignment device.

This paper reports the development of an instrumented flexible electrogoniometric hand posture corrective device designed specifically for monitoring and controlling the range of motion (ROM) at the hand and wrist. The device, known as the wrist alignment device (WAD), consists of flexible electrogoniometers attached to a Lycra glove and a control box housing the WAD circuitry. The WAD controls the wrist ROM within set limits by means of presetting the joint angle ranges prior to commencing measurements, thereby preventing or reducing extreme wrist ulnar deviation, wrist hyperflexion, and wrist hyperextension. Additionally, the device consists of a window comparator, which allows the joint movement always to remain within the set limits. Where the subject's wrist ROM is outside the presettings, a piezo-buzzer is triggered which alerts the subject to reduce the ROM, thereby ensuring that the joint angles are always kept within the preset angle range. All instrumentation associated with the development of the device underwent calibration. As a device, it has widespread applications within the office and clinical environment. Preliminary results indicate that reliable measurements based on ROM settings can be obtained when using the WAD.

A multi-segment kinematic model of the foot with a novel definition of forefoot motion for use in clinical gait analysis during walking.

A multi-segment kinematic model of the foot was developed for use in a gait analysis laboratory. The foot was divided into hindfoot, talus, midfoot and medial and lateral forefoot segments. Six functional joints were defined: ankle and subtalar joints, frontal and transverse plane motions of the hindfoot relative to midfoot, supination/pronation twist of the forefoot relative to midfoot and medial longitudinal arch height-to-length ratio. Twelve asymptomatic subjects were tested during barefoot walking with a six-camera optical stereometric system and auto-reflective markers organized in triads. Repeatability of the joint motions was tested using coefficients of multiple correlation. Ankle and subtalar joint motions and twisting of the forefoot were most repeatable. Hindfoot motions were least repeatable both within-subjects and between-subjects. Hindfoot and forefoot pronation in the frontal plane was found to coincide with dropping of the medial longitudinal arch between early to mid-stance, followed by supination and rising of the arch in late stance and swing phase. This multi-segment foot model addresses an unfortunate shortcoming in current gait analysis practice-the inability to measure motion within the foot. Such measurements are crucial if gait analysis is to remain relevant in the orthopaedic and rehabilitative treatment of the foot and ankle.

Re-attachment of the tuberosities of the humerus following hemiarthroplasty for four-part fracture.

This study evaluated the effect on movement under load of three different techniques for re-attachment of the tuberosities of the humerus using test sawbones. In the first, the tuberosities were attached both to the shaft and to each other, with one cerclage suture through the anterior hole in the prosthesis. The second technique was identical except for omission of the cerclage suture and in the third the tuberosities were attached to the prosthesis and to the shaft. An orthogonal photogrammetric system allowed all segments to be tracked in a 3D axis system. The humeri were incrementally-loaded in abduction, and the 3D linear and angular movements of all segments were calculated. Displacement between the tuberosities and the shaft was measured. The first and second techniques were the most stable constructs, with the third allowing greater separation of fragments and angular movement. Separation at the midpoint of the tuberosities was significantly greater using the latter technique (p < 0.05). The cerclage suture added no further stability to the fixation.

Direct comparison of calculated hip joint contact forces with those measured using instrumented implants. An evaluation of a three-dimensional mathematical model of the lower limb.

Characterisation of hip joint contact forces is essential for the definition of hip joint prosthesis design requirements. In vivo hip joint contact force measurements have been made using instrumented hip joint prostheses. However, to allow determination of the range of values of joint contact force and their directions relative to anatomical structures in a range of subject groups sufficient to form an agreed data base it is necessary to adopt a different approach without the use of an implanted transducer. The use of mathematical models of the lower limb to examine the forces in soft tissues and at the joints has provided valuable insight into internal loading conditions. Several authors have proposed mathematical musculo-skeletal models. However, there have been only limited attempts at validation of these models. It is possible to use the results of in vivo force measurements from instrumented prostheses to validate the results calculated using the mathematical models. In this study two subjects with instrumented hip joint prostheses were studied. Forces at the hip joints were calculated using a three-dimensional model of the leg. Walking at slow, normal and fast speeds (0.97-2.01m/s), weight transfer from two to one leg and back again, and sit to stand were studied. Direct comparisons were made between the 'gold standard' measured hip joint contact forces and the calculated forces. There was general agreement between the calculated and measured forces in both pattern and magnitude. There were, however, discrepancies. Reasons for these differences in results are discussed and possible model developments suggested.

A biomechanical analysis of the rheumatoid index finger after joint arthroplasty.

OBJECTIVE: To determine the mechanisms responsible for the recurrence of ulnar drift after metacarpophalangeal joint arthroplasty in the rheumatoid hand. DESIGN: A three-dimensional biomechanical model of the index finger joints was used to predict the implant loads during several activities of daily living. BACKGROUND: Post-operative clinical evaluation of Sutter metacarpophalangeal prostheses shows a high incidence of fracture and recurrent deformity. METHODS: A six-component force transducer in conjunction with a six-camera motion analysis system were used to obtain kinematic and external loading data from eight patients with rheumatoid arthritis during several simulated activities. These data were used as input into a three-dimensional biomechanical model of the implant and interphalangeal joints of the index finger. Tendon lines of action and moment arms were obtained using a series of MRI scans and CAD modelling techniques. RESULTS: Implant forces were oriented in a radial and dorsal direction to resist the ulnarpalmarly pull of tendons associated with the metacarpophalangeal joint. CONCLUSIONS: The recurrence of ulnar drift is attributable to fatigue failure of the prostheses. After fracture the implant is unable to support the repetitive loading patterns experienced during activities of daily living. RELEVANCE: Understanding the mechanisms responsible for the recurrence of ulnar drift and implant failure is a step towards improving the prosthesis design, surgical procedures and ultimately the patient's prognosis.

Hip joint contact forces in normal subjects and subjects with total hip prostheses: walking and stair and ramp negotiation.

OBJECTIVE: To calculate the hip joint contact force in normal subjects and subjects with total hip replacements. DESIGN: An observational study of age matched normal subjects and subjects with hip joint replacements. BACKGROUND: Hip joint contact forces have been calculated using musculo-skeletal models and measured in vivo using instrumented hip prostheses. There are few examples of studies performed on subjects in the 40-60 year age range. This study characterises the forces in both normal subjects and subjects with hip joint replacements for these 'young' subjects. METHODS: Motion analysis and force plate data were used as input to a three-dimensional model of the leg. Five male and six female normal subjects and five male subjects with hip prostheses were studied. Each subject was observed walking and negotiating stairs and a ramp. RESULTS: Hip joint contact forces in both thigh and pelvic-based co-ordinate systems are presented. Subjects cadence, speed and stride length are given. CONCLUSIONS: In general subjects with hip replacements exhibited lower hip joint contact forces than age matched normal subjects. It is suggested that this was the results of the lower speeds, stride lengths and cadences adopted by the subjects with hip replacements. RELEVANCE: The characterisation of hip joint contact forces provides essential information for prosthetic joint design and testing. The comparison of hip joint contact forces in normal subjects with those in subjects with prosthetic joints provides evidence of, not only actual use of joints, but also of possible levels of force that might be applied to hip prostheses if subjects returned to normal use.

Functional and biomechanical assessment of the normal and rheumatoid hand.

OBJECTIVE: To assess hand function in accordance with its accepted definition and to compare the results of three different assessment techniques. DESIGN: A clinical-type assessment was used together with measurement of pinch grip and three-dimensional biomechanical trials. BACKGROUND: Traditional clinical assessment may not relate to a patient's actual hand function. If hand function is defined as "the ability to use the hand in daily activities" then it is more appropriate to measure the forces available for performing everyday tasks using biomechanical tests. METHODS: Eight female patients with rheumatoid arthritis and eight control subjects were recruited for the study. Volunteers underwent a clinical-type assessment using a six-task activity board. Lateral pinch grip of both hands was measured using a custom-built transducer. Biomechanical trials were conducted using a 6 degree-of-freedom transducer and 6-camera motion analysis. RESULTS: Functional differences between the two subject groups were apparent using all three methods of assessment. Pinch strength correlated well with the biomechanical trial data but results from the clinical-type assessment provided only a weak correlation. CONCLUSIONS: Clinical-type assessments do not give an accurate measure of hand function. Pinch strength measurements can provide a cost-effective alternative to full biomechanical analysis. RELEVANCE: Traditional functional assessment uses measurements of grip or pinch strength and range of motion together with a subjective assessment of activities of daily living. This study demonstrates that pinch strength measurements can provide an accurate measure of hand function. The results from activity-board trials do not reflect hand ability and are of limited use for hand evaluation.

A novel instrumented ring for the measurement of grip force adjustments during precision grip tasks.

A wide range of scientific and clinical research studies use the measurement of grip force to quantify hand function and activities during daily living. Many applications of instrumented objects can be found in the biomechanical and neurophysiological literature. However, these were found not to be suitable for the measurement of grip force and force modulations during precision grip independently from the hand orientation. The low-cost precision grip force transducer described here is capable of recording magnitude, direction and modulation of the force exerted on a closed ring. The design is based on a standard proving ring, onto which a second set of strain gauges is applied. The outputs of both Wheatstone bridges yield a unique signature for every position under a two-point load. The tested aluminium ring had an outer diameter of 83 mm, a wall thickness of 3 mm and a height of 12 mm. With eight single bending strain gauges used, the maximum load was 100 N. During a grip task, tremor components from d.c. to 45 Hz could be detected. The newly developed ring might therefore find a use in many biomechanical and neurophysiological studies as a tool for measuring grip force and its fine modulations.