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Complications related to patellar resurfacing are well recognized. We present an unusual case where the patellar button, after separating from the patella, extruded from the knee joint to lie within the extra-articular soft tissues.

The effect of surgery for femoral neck fracture on lower limb venous blood flow and its relationship to deep vein thrombosis was investigated in 179 patients. Blood flow was measured using strain gauge plethysmography before surgery, in the 1st week after surgery, and at 6 week review. There was a significant reduction in both venous outflow and venous capacitance, affecting both fractured and non-fractured legs but significantly greater in the fractured leg. Venous function remained significantly impaired in both lower limbs 6 weeks after surgery. There was a significant correlation between the reduction in venous function and the development of deep vein thrombosis.

The effect of surgery for femoral neck fracture on whole blood coagulation and the relationship of altered coagulation to deep venous thrombosis were investigated in 250 patients. Whole blood coagulation was measured using thrombelastography preoperatively, in the early postoperative period and at 6-week review. Significant hypercoagulability was demonstrated after surgery and persisted to 6-week review. A significant correlation between hypercoagulability and the development of deep venous thrombosis is demonstrated. Hypercoagulability is shown to be a major factor in thrombosis formation following proximal femoral neck fracture surgery.

The mechanisms by which graduated compression stockings prevent deep venous thrombosis are not completely understood. In the current study the physiologic effect of low-pressure graduated compression stockings on the venous blood flow in the lower limb and the practical aspects of their use were assessed. Patients having elective orthopaedic surgery at a university orthopaedic department were randomized into five groups to wear two different types of graduated compression stockings in thigh and knee lengths. Patients in the fifth control group did not wear graduated compression stockings. Venous occlusion strain gauge plethysmography was used to measure venous flow. After 20-minutes bed rest there was a highly significant increase in venous capacitance and venous outflow in patients in all of the four groups wearing stockings. There was no difference in the mean of the percentage change of venous capacitance in patients in the four groups wearing stockings. The knee length Brevet stockings were less efficient in increasing the venous outflow. There was no significant change in the venous capacitance and venous outflow in patients in the control group. Visual assessment of the fit and use of stockings was done, and patients' subjective opinion of comfort was sought. The knee length graduated compression stockings wrinkled significantly less, and significantly fewer patients reported discomfort with them. All stockings were reported to be difficult to use. Thigh and knee length stockings have a significant effect on decreasing venous stasis of the lower limb. Knee length graduated compression stockings are similarly efficient in decreasing venous stasis, but they are more comfortable to wear, and they wrinkle less.

Strain gauge plethysmography (SGP) is a non-invasive method used in the detection of deep venous thrombosis (DVT). The technique is based on the measurement of calf volume changes in response to venous occlusion by a thigh cuff, the volume changes reflecting the rates of arterial inflow and venous outflow. A numerical model of the blood circulation within the limb and the response of this to a SGP test has been derived, based on treating the different parts of the circulatory system in the leg as resistance and capacitance elements. The simulation results were compared with clinical studies and support the ability of SGP to detect non-occlusive clots of more than 50-60% of the lumen, as well detecting calf vein occlusion. The non-linear behaviour of the venous compliance with intra-luminal pressure appears to be a particularly important factor within the model. In addition, increases in venous tone due to post-operative venospasm were shown to be a potential source of false positive results.

A postal survey was carried out to determine the attitudes to the use of low molecular weight heparin (LMWH) in joint replacement among two representative groups of orthopaedic surgeons practising in the UK. 72% of hip surgeons and 51% of knee surgeons replying had used LMWHs for deep vein thrombosis prophylaxis in joint replacement patients. Of these, 48% had discontinued LMWH use due to bleeding complications. Among those continuing to use LMWHs, 88% had witnessed excessive bruising around the wound and 53% had experienced increased wound bleeding or haematomas. Although LMWHs have been shown to reduce post-operative thromboembolism in these groups, clinical experience has revealed an increased incidence of bleeding complications associated with their use. This has prevented their routine use in joint replacement, as was the case with unfractionated heparin in the past.

Surgeons often encourage patients to move their feet in an attempt to prevent venous stasis, but there is little evidence that this measure is beneficial. We investigated the effect of active movement of one foot on the venous blood flow four days after total hip replacement. The actual venous outflow at rest was measured with use of venous occlusion strain-gauge plethysmography in thirty-eight patients. The patients were randomly allocated to the control group (eighteen patients) or the exercise group (twenty patients). A baseline measurement was followed by a one-minute period of rest (control group) or of maximum plantar flexion and dorsiflexion of the foot, ankle, and toes at a rate of thirty cycles per minute (exercise group). The venous outflow was measured again at two, seven, twelve, and thirty minutes in both groups. Movement of the foot for one minute produced a significant and sustained increase (p < 0.002) in the venous outflow (mean maximum increase, 22 per cent). The value remained greater than the baseline level for thirty minutes (mean increase, 6.5 per cent) (p < 0.2). The increase was gradual, reaching a maximum twelve minutes after the completion of exercise. Our results confirm the beneficial hemodynamic effects of active movement of the foot in the postoperative period and suggest that patients should move the feet and ankles postoperatively as part of a prophylactic regimen directed at decreasing the risk of venous thrombosis.

We studied the effect of total knee replacement on venous flow in 110 patients. Resting venous blood flow was measured using strain-gauge plethysmography before operation, after surgery and after discharge from hospital. There was a significant reduction in mean venous capacitance (p < 0.001) and mean venous outflow (p < 0.004) affecting only the operated leg. Both improved significantly after mobilisation in the early postoperative period, returning to preoperative levels by six days after surgery and before discharge from hospital. Our findings showed that venous stasis may contribute to deep-vein thrombosis only in the first few days after total knee replacement. This would be the most important period for the use of flow-enhancing prophylactic devices. Comparison with changes in blood flow after total hip replacement identified different patterns of altered haemodynamics suggesting that there are different mechanisms of venous stasis and thrombogenesis in hip and knee arthritis and during surgery for these conditions.

OBJECTIVE: This study aimed to establish a basis of descriptive data for the sit-stand-sit movement cycle in 50 normal subjects, 25 male and 25 female, aged between 20.1 and 78.3 years (mean age 46.8 years). DESIGN: A descriptive design was employed to establish the characteristics of the activity in normal subjects. BACKGROUND: Research has been carried out into kinetic and kinematic characteristics of the sit-to-stand movement, but few researchers have considered stand-to-sit. Most studies have involved small samples, subjects with pathology, or elderly subjects, so a baseline of data from normal subjects has not yet been established. METHOD: Linear displacement and acceleration of the trunk and angular displacement of the knee were recorded simultaneously within the same temporal framework. The measurement system consisted of a vector stereograph, and triaxial accelerometers located at the level of C(7), and an electrogoniometer located at the lateral aspect of the knee. Subjects rose from and descended to the seated position a total of six times at their own self-selected speed. Numerical data were subjected to descriptive analysis, matched-pairs t tests and Pearson's rho correlations. RESULTS: Mean values for the time to rise was 1.91 s and to descend was 1.97 s. Forward lean velocity was greater during rising than descending (P < 0.001), and recovery velocity was greater during descending than rising (P < 0.001). Temporal contributions of forward lean and vertical displacement and the period of overlap between them were identified, and relationships between acceleration and temporal events and components were established. Differences existed among groups, involving primarily the elderly groups and occurring during the rising phase. CONCLUSIONS: This study has proposed a baseline of descriptive data in normal subjects for the sit-stand-sit movement cycle. RELEVANCE: In practical and clinical applications of information gained from analysis of functional activities, establishment of what is accepted as 'normal' is necessary before abnormalities can be identified and analysed, and intervention implemented and evaluated. This study provides that basis.

This study was designed to determine gait patterns in children with lumbar and sacral neurologic level spina bifida. We studied a group of 28 children: 10 had L4-level lesions and a mean age of 11 years; eight had L5-level lesions and a mean age of 8 years; and 10 had S1-level lesions with a mean age of 12 years. A group of 15 normal children, mean age 10 years, was used for comparison. Each child underwent three-dimensional gait analysis using the Vicon system. We found that there were recognisable gait patterns for each level of spina bifida and that the abnormalities accurately reflected the muscle deficiencies present. The gait patterns approximated more closely to those of the normal group as the neurological level descended. The most important findings were of increased pelvic obliquity and rotation with hip abduction in stance (reflecting the gross Trendelenburg-type gait seen in these children) and persistent knee flexion throughout stance as a result of the absence of the plantar flexion-knee extension couple. We found that gait was not improved by tendon transfers performed either at the hip (posterolateral psoas transfer) or at the ankle (tibialis anterior transfer).

This study compared the osteoinductive properties of six different bone graft substitutes: Pyrost, natural coral, Callopat, Surgibone, demineralized Surgibone and demineralized rat bone. The materials were implanted heterotopically, in the abdominal musculature of rats, and the results evaluated histologically at 3 and 6 wk post-implantation. Surprisingly, the results showed that both the demineralized rat bone and demineralized Surgibone were less osteoinductive than might be believed from the literature. Mineralized grafts showed no sign of new bone formation and exhibited variable resorption patterns. A layer of what appeared as dense calcification was seen around the coral implant. The most intense inflammatory reactions were exhibited with the xenografts Surgibone and demineralized Surgibone, indicating persistent immune responses. Coral and Pyrost elicited no marked inflammatory response, and this was attributed to the negligible amounts of protein present in these materials.

Serum and synovial tissue from 26 patients with rheumatoid arthritis (RA) (according to the diagnostic criteria of the American Rheumatism Association) and 26 patients with osteoarthritis (OA) were examined. Among the RA group, the female to male ratio was 4.2:1, and the age range was 44-82 yr with a mean of 64.0 yr; joints from which synovium was sampled were hip (n = 12), knee (n = 9), ankle (n = 3) and shoulder (n = 2). The duration of rheumatoid disease ranged from 6 to 24 yr with a mean of 13.9 yr. Among the OA group, the female to male ratio was 2.25:1, and the age range was 51-88 yr with a mean of 68.2 yr; joints from which synovium was sampled were hip (n = 18) and knee (n = 8). Twenty-one patients from the RA group and 20 patients from the OA group had evidence of previous parvovirus B19 infection (serum anti-B19 IgG), and all patients from both groups were serum anti-B19 IgM negative. Synovial sections from all 52 patients were stained with mouse monoclonal antibodies, 3H8 (to B19 capsid proteins) and alpha-P (to blood group P antigen). All tissue sections examined were found to be negative for both B19 capsid proteins and blood group P antigen. Using a nested polymerase chain reaction (PCR) assay, all patients were negative for serum B19 DNA. However, B19 DNA was demonstrated in the synovium of 10 of 26 RA patients and 9 of 26 OA patients; uncorrected chi 2 value = 0.08; degrees of freedom = 1; P = 0.77. All 19 patients testing positive for synovial B19 DNA had evidence of prior exposure to B19 infection (serum anti-B19 IgG). In conclusion, although there is published evidence of chronic rheumatoid-like arthropathy following acute parvovirus B19 infection, our findings do not support the involvement of B19 in the aetiopathogenesis of RA.

To determine the incidence of congenital hip dislocation (CDH) a retrospective study was carried out of cases occurring in a defined population using multiple information sources. Of 138,600 children born in the period 1983-1987, a total of 243 were diagnosed with CDH, defined as those requiring splintage or surgery whose treatment extended beyond 6 months of age. Incidence and estimates of relative risks for pre-disposing factors were determined. The rate was 1.75 cases per 1000 livebirths. Major risk factors were female gender and breech presentation. The proportions of cases identified before 1, 3 and 6 months of age were 8, 14 and 35%, respectively. Despite using a restrictive definition, we have obtained an incidence rate among the highest reported in any United Kingdom population. Early detection is widely accepted as desirable, but neonatal screening has proved ineffective.

We reviewed 43 patients using clinical scoring for evidence of postphlebitic syndrome at least 5 years after hip replacement. All had had a venogram as part of a screening study at the time of surgery. The postphlebitic syndrome was identified in 13 patients and was disabling in 6. The syndrome was present in 9 of the 11 patients with a venographically proven deep vein thrombosis (DVT) and in 4 of the 32 without DVT. Postphlebitic sequelae had developed despite anticoagulant therapy for the acute DVT. The postphlebitic syndrome following asymptomatic deep vein thrombosis is an important long-term complication of total hip replacement.

Congenital dislocation of the hip (CDH) affects two children per 1000, with potentially serious consequences. Student health visitors in Northern Ireland learn screening techniques for CDH at a half-day workshop at a regional hospital. In order to evaluate the adequacy of this preparation, 71 qualified health visitors were surveyed to assess their knowledge relating to CDH, their views on the adequacy of the training, and their opinions about referral of positive cases. Knowledge in some areas was poor and preparation was considered too short. Direct referrals of positive cases to orthopaedic clinics, without a general practitioner acting as an intermediary, was a frequently cited desire. Recommendations include extending the training for those involved in CDH screening while ensuring that experienced health visitors, from whom novices learn, are themselves using correct procedures.

Objective: To investigate if those responsible for screening for neonatal hip instability are using acceptable manual hip stress tests as described by Ortolani and Barlow., Method: A video camera was used to record the technique of 35 personnel who were responsible for screening. They examined both a baby and a simulator. The study comprised five groups, classified by experience and practice: senior orthopaedic surgeons, senior paediatric staff, junior paediatric staff, nurses, community staff., Results: The seven authors together with six independent expert observers viewed the video and marked the performance with the aid of a specially designed proforma. Although there was some variation between these expert observers, the results showed differences in the scores obtained by the different groups of examiners over all aspects of the test procedure., Conclusion: Video recording for critical analysis and feedback is a useful technique in this situation. Overall, the results suggest that testing for neonatal hip instability was inadequate. A variety of hip stress manoeuvres were being performed. The ability of each subject to perform satisfactory tests seemed to depend on their experience and education. More "hands on" training and experience of testing might provide the necessary competency for screening.

A study of physiological patellofemoral crepitus (PPC) signal recorded from adolescent knees has yielded information which suggests that decay time of PPC amplitude due to continuous passive motion (CPM) activity is a consistent and useful signature variable for a given knee. The PPC vibrational signal was induced in each case by 1 min of static load on the patella and postural variables during the examination were carefully controlled. The speed of CPM has been noted as a factor directly influencing the rat of PPC amplitude decay; specifically, a higher CPM speed contributes to an increased decay constant at a cost of increased inter-subject variability. It is proposed that CPM might form an important basis for the ultimate development of a computer-based auscultation technique for diagnosis of patellofemoral joint disorders.

In this study, the levels of the cysteine proteinase--cathepsin B were measured in diseased synovial fluids using a steady state fluorometric assay. Cathepsin B-like activity was shown to be present in all the samples analysed, with the rheumatoid arthritic synovial fluids possessing significantly higher concentrations (mean value ca. 416 mg/l) than the osteoarthritic fluids (mean value ca. 142.4 mg/l). In addition, upon treatment with pepsin, all of the rheumatoid arthritis samples were shown to possess additional cathepsin B-like activity, suggesting the presence of a reservoir of latent precursor molecules. By utilising a recently developed biotinylated affinity label for cathepsin B-like proteinases and sheep anti-(human cathepsin B) antibodies, used in combination with SDS-PAGE and Western blotting, the rheumatoid arthritic synovial cathepsin B was shown to exist in two forms with apparent molecular masses of M(r) 29,000 and 42,000. We propose that the former is a functionally active proteinase, whereas the latter is a pepsin activatable proform which, when cleaved by this aspartyl proteinase, is converted into a catalytically competent species of M(r) 20,000.

The drawbacks of freshly harvested autologous bone have resulted in the search for an alternative, capable of supporting osteogenic cell growth. This capability was examined in potential bone graft materials by culturing human osteoblasts on each material. Test materials included rat bone, Surgibone, Ostilit, Biocoral and Tisseel. After 3 days osteoblasts had adhered to all materials, except Ostilit. With increasing time the cells multiplied on the materials, to varying extents. Cell affinity was greatest for rat bone and Tisseel. Fewer cells attached to Biocoral and Surgibone. Thus all the materials, with the exception of Ostilit, were biocompatible for human osteoblasts.

The screening for Developmental Dysplasia of the Hip in infants relies on the two manipulative tests developed by Ortolani and Barlow which are often poorly performed. This study investigated the forces applied and the sequences of physical manoeuvres underlying the tests in order to define a standard of safe practice. Eight subjects examined the hips of two training models that closely simulated the behaviour of a range of infant hip pathologies. The forces applied and the manoeuvres employed during each examination were recorded using a purpose-built force and displacement transducer system. The analysis concentrated on the peak forces and the biomechanical conditions necessary to detect an abnormality. The models' legs had to be abducted beyond certain critical angles in order to dislocate and relocate an unstable femoral head and the magnitude of the force required to dislocate the femoral head was significantly less than the peak force applied (12 N vs 33 N, p < 0.001). Also, the Palmen test, a less well known technique, provided the same level of diagnostic performance as the Barlow test but with a lower peak applied force (28 N vs 47 N, p < 0.001). Changes are therefore necessary to the training programmes for medical staff to ensure that the range of abduction during the manoeuvres is large enough to encompass the likely range of critical angles and that the forces applied are just sufficient so as not to overstress the joints.

Familial expansile osteolysis is a rare bone dysplasia which is transmitted as an autosomal dominant trait in a large kindred in Northern Ireland. The gene which causes the disease shows tight linkage with several polymorphic markers on chromosome 18q with a maximum lod score of 11.53 at a recombination fraction of 0.00 with D18S64. The gene is flanked by D18S35 and D18S61 and is located at chromosome 18q21.1-q22. Mapping a new locus for a gene involved in regulation of bone metabolism may also have implications in the study of Paget's disease of bone which is a common related bone dysplasia.

Thirty consecutive cases requiring total knee replacement (TKR) were treated using the Richards Tricon Total Knee System with ASAP (All Six, All Precise) instrumentation (Richards Medical Company, Memphis, TN, USA). Preoperative and postoperative overall coronal alignment were measured using long-leg anteroposterior X-rays. The femoral and tibial bone cuts in this plane were assessed using intraoperative films. The aim was to achieve a postoperative coronal tibio-femoral alignment of 7 degrees valgus. The mean preoperative alignment was 1 degree valgus (SD = +/- 13.5 degrees). A mean postoperative alignment of 8 degrees valgus was obtained (SD = +/- 5.6 degrees). The results obtained in this series suggest that the ASAP system with careful use simplifies the technique of total knee replacement while maintaining accuracy.

The diagnosis of deep vein thrombosis after total joint arthroplasty is difficult. The most widely used method of detection is physical examination and selective venography, which are unreliable and expensive even when symptoms and signs are prominent. This study employed computerized strain gauge plethysmography (CSGP) to select symptomatic patients for venography. The incidence of detection by CSGP was increased from 16% to 81.7%. Repeated CSGP also was investigated, but although specificity was further enhanced, it was at the expense of sensitivity. The negative predictive value of the CSGP screening was high and comparable to that of venography and indicates that CSGP is useful in the management of patients with symptoms suggestive of deep vein thrombosis. Computerized strain gauge plethysmography results emphasize the low specificity and poor feasibility of clinical examination and venography. Computerized strain gauge plethysmography is strongly advocated as a selection procedure for invasive venography in total joint arthroplasty patients.

Demineralized human bone used as an autologous bone graft substitute is ethylene oxide sterilized, which is reported to reduce the bone's osteoinductive potential. To determine the minimum sterilization time required and the effect of ethylene oxide on bone's osteoinductive capacity and chemical structure, samples were exposed to ethylene oxide for different times (5-240 min). Results showed that 1 h exposure sterilized the bone (assessed by Attests). This exposure time reduced the bone's osteoinductive potential and caused surface ultrastructural changes. These findings raise questions concerning the suitability of ethylene oxide for sterilizing demineralized human bone.

1. A 1H-n.m.r. method was used to measure concentrations of valine, alanine, lactate, acetate, hyaluronan and lipids in synovial fluid obtained, during the normal course of examination from the knee joints of patients attending rheumatology and orthopaedic clinics. Fluid was available from 16 patients with osteoarthritis, 18 patients with rheumatoid arthritis, four patients with meniscal tear and one patient each with systemic lupus erythematosis, mono-arthritis, synovitis and loose bodies. Four normal specimens were obtained for comparison. 2. Valine, alanine and acetate levels all showed a normal Gaussian distribution, reflecting the distributions within the serum of the sample population. 3. Lactate concentrations divided into two distinct patterns. At concentrations below 2.5 mmol/l the lactate levels showed a Gaussian distribution, reflecting the distribution in normal serum. The normal synovial fluid specimens belong to this distribution. Above 2.5-3.0 mmol/l, lactate levels were asymmetric in distribution with a long tail at higher concentrations. These high levels of lactate can be explained by the generation of lactate through anaerobic metabolism within the synovial cavity. This metabolic process is triggered by a general inflammatory condition such as in rheumatoid arthritis. 4. The distribution of n.m.r.-observable lipid concentrations in rheumatoid arthritis and osteoarthritis each shows a normal distribution and the mean concentration is significantly higher in rheumatoid arthritis. 5. An increased n.m.r.-observable hyaluronan concentration is associated with an inflammatory situation. 6. It is concluded that raised levels of lactate and n.m.r.-observable hyaluronan and lipids are useful markers to aid the clinical distinction between rheumatoid arthritis and osteoarthritis.(ABSTRACT TRUNCATED AT 250 WORDS)

Developmental dysplasia of the hip (DDH) is a term used to describe a group of disorders of the neonatal hip in which the head of the femur is unstable or incongruous in relation to the acetabulum. Early detection and treatment of the condition generally results in normal development, whereas late diagnosis has poor success. In Northern Ireland, despite all neonates being manually examined for hip disorders by a medical officer before hospital discharge, there is an unacceptable late diagnostic rate of almost 50% of all cases. To help reduce the number of late presentations, vibration arthrometry, a noninvasive form of screening for DDH, has been used to record hip vibration events during clinical testing. In a comparative study, 300 infants were examined by nurses and medical officers to establish the sensitivity of manual palpation to neonatal hip vibrations detected by the objective detection system. Experienced research nurses detected 86% of the signals; doctors in training detected less than 10%. This suggests that objective, noninvasive screening by vibration arthrometry would detect a higher proportion of vibration events in neonates during the early stages of DDH. More time should be invested in training medical officers and others involved in DDH screening.

This paper discusses a survey which was carried out to investigate the types of risks and inconveniences which are normally disclosed by surgeons before operations. By restricting the survey to a specific operation, the Charnley Hip Replacement procedure, greater precision in replies was obtained. The results, however, shed light on both the medical and the legal aspects of informed decision in surgery generally. The survey data was analysed using the concept of neighbourhood consensus [1: Dodd F. J. and Donegan H. A. Proc. of ILIAM 6, pp. 17-29. University of Ulster Press, Ulster, 1989].