PubMed Health⌕ Search

Biomedical subjects

A van Kampen

Publications and source records attributed to A van Kampen.

At least 19 recordsLinked to original sources
PubMed2006

[Simple diagnostics of patellofemoral instability point to tailored treatment].

Three patients presented with patellar instability. On physical examination, the first patient, a 20-year-old male soccer player, reported pain at the medial insertion ofthe medial patellofemoral ligament (MPFL) after a traumatic patella luxation. He was successfully treated by MPFL reconstruction. The second patient, an 18-year-old woman, presented with patellofemoral pain. On physical examination, the patella could be luxated laterally over approximately half of its width. Conventional X-rays showed a crossing sign, indicating trochlear dysplasia. She was treated by trochleaplasty. The last patient, a 15-year-old girl, presented with patellofemoral instability. On physical examination, a patella alta could be palpated. She was advised to undergo tuberositas distalisation after her epiphyseal growth plates had closed. Patients with patellofemoral instability must be distinguished from patients with patellofemoral-pain syndrome. Simple physical examination and conventional X-rays usually suffice to make this distinction. The treatment is tailored to the pathology found.

Adolescent↗
PubMed2005

The Ilizarov external fixator: what remains of the wire pretension after dynamic loading?

BACKGROUND: Maintenance of wire pretension in an Ilizarov external fixator is dependent on the torque applied to the fixation bolts. We therefore measured immediately after surgery the clinically applied torques. The median value was only 10 N m (range 8-14N m). We wondered whether this value is appropriate to maintain the wire pretension and thereby to achieve sufficient fracture stability during dynamic loading of the device for a longer period. METHODS: A material testing machine dynamically loaded one wire mounted on one ring. Several configurations were tested. RESULTS: A quick decrease in wire tension to a steady state situation was seen. In the most stable configuration (20 N m wire fixation torque) 50% of the initial 90 kg wire pretension remained after dynamic loading with 200 N. In the least stable configuration (10 N m torque) considerable wire slippage occurred even without loading and no tension remained after loading! No plastic deformation of the wires was observed so loss of wire tension was due to slippage of the wires through the fixation bolts. INTERPRETATION: With the small fixation torques used in clinical practice considerable wire tension is lost even after a few loading cycles. Further research should address the question whether preservation of a higher wire tension during long term loading promotes faster fracture healing.

Bone Wires↗
PubMed2005

Fractures of the scapula surgical neck: outcome after conservative treatment in 13 cases.

BACKGROUND: Conservative treatment of fractures of the scapular neck does not uniformly lead to a success. The purpose of this retrospective study was to analyze the occurrence of glenoid displacement in conservatively treated patients with a scapular neck fracture without concomitant shoulder girdle injury in relation with the clinical outcome. METHODS: Between 1991 and 2001, 177 patients with a fracture of the scapula were treated in two Dutch clinics. Twenty-four patients sustained a scapular neck fracture, who all, with the exception of one, were treated non-operatively. At follow-up, 13 patients had a functional evaluation and were assessed clinically at an average of 5.5 years after the injury. RESULTS: All fractures healed uneventfully. At final radiographic evaluation, four patients were found with significant translational displacement of fracture fragments (>1 cm); however, no angular displacement of the glenoid was found (no GPA < 20 degrees ). The functional outcome of the 13 patients was excellent (Constant score: 90). No correlation was found between functional outcome and malunion. There was no significant difference between the SF-36 scores in the follow-up group and the scores for age-matched controls in the general population. CONCLUSIONS: Non-operative treatment of a surgical neck fracture of the scapula in absence of an ipsilateral shoulder injury and associated permanent neurological impairment leads to a good to excellent functional outcome, with or without significant translational displacement.

Adolescent↗
PubMed2005

Avoiding rotational malalignment after fractures of the femur by using the profile of the lesser trochanter: an in vitro study.

INTRODUCTION: Intramedullary (IM) nailing has become the preferred method of treatment for femoral shaft fractures in adults. Rotational malalignment is an important complication, established during operation. The incidence of rotational malalignment (> or = 15 degrees) has been reported to be between 20% and 30%. It might be avoided intra-operatively by using quantitative imaging techniques, with the profile of the contralateral lesser trochanter serving as a reference. MATERIALS AND METHODS: With the help of a C-arm image intensifier, five surgeons tried to determine the neutral state of ten prepared cadaver femora. They could only look at the C-arm screen and were blinded to the actual femur. Per observer three measurements were done per femur. The first measurement (method I) was done without a reference, while the second (method II) used a reference image of the femur in a neutral state. The third method (method III) added a lesser trochanter quantifying computer program. After positioning of the femur, the difference in rotational state compared with the neutral state was measured with an inclinometer. RESULTS: Without reference, malrotations up to 27 degrees were found. Methods II and III proved to be significantly better (p < 0.0001). These two methods showed malrotation of 2.2 degrees (+/-1.5 degrees) and 2.3 degrees (+/-1.7 degrees), respectively. External or internal malrotation occurred with all three methods equally frequently. No difference was found between observers. CONCLUSIONS: Using the contralateral lesser trochanter as a reference is an accurate method to minimize malrotation of a femur. Quantifying the profile of the lesser trochanter with computer assistance did not improve these results. Clinical results in the future still have to support these in vitro findings.

Bone Malalignment↗
PubMed2005

Human syndromes with congenital patellar anomalies and the underlying gene defects.

Genetic disorders characterized by congenital patellar aplasia or hypoplasia belong to a clinically diverse and genetically heterogeneous group of lower limb malformations. Patella development involves different molecular and cellular mechanisms regulating dorso-ventral patterning, cartilage and bone formation along endochondral ossification pathways, and growth. Several human genes that are important for patella development have been uncovered by the study of human limb malformation syndromes, yet causative genes for many more such disorders await to be identified and their complex interactions in the developmental pathways deciphered. Mutant animal models of congenital patellar aplasia or hypoplasia are certainly instrumental to create more insight into this aspect of limb development. Moreover, investigation of the complete phenotype of human syndromes and animal models may reveal novel insights into the pleiotropic roles of the responsible genes in the normal developmental of other organ systems. In this review, the phenotype and gene defects of syndromes with congenital patellar aplasia or hypoplasia will be discussed, including the nail patella syndrome, small patella syndrome, isolated patella aplasia hypoplasia, Meier-Gorlin syndrome, RAPADILINO syndrome, and genitopatellar syndrome.

Animals↗
PubMed2005

A three-dimensional dynamic finite element model of the prosthetic knee joint: simulation of joint laxity and kinematics.

For testing purposes of prostheses at a preclinical stage, it is very valuable to have a generic modelling tool, which can be used to optimize implant features and to avoid poor designs being launched on to the market. The modelling tool should be fast, efficient, and multi-purpose in nature; a finite element model is well suited to the purpose. The question posed in this study was whether it was possible to develop a mathematically fast and stable dynamic finite element model of a knee joint after total knee arthroplasty that would predict data comparable with published data in terms of (a) laxities and ligament behaviour, and (b) joint kinematics. The soft tissue structures were modelled using a relatively simple, but very stable, composite model consisting of a band reinforced with fibres. Ligament recruitment and balancing was tested with laxity simulations. The tibial and patellar kinematics were simulated during flexion-extension. An implicit mathematical formulation was used. Joint kinematics, joint laxities, and ligament recruitment patterns were predicted realistically. The kinematics were very reproducible and stable during consecutive flexion-extension cycles. Hence, the model is suitable for the evaluation of prosthesis design, prosthesis alignment, ligament behaviour, and surgical parameters with respect to the biomechanical behaviour of the knee.

Arthroplasty, Replacement, Knee↗
PubMed2004

Displacement of the medial meniscus within the passive motion characteristics of the human knee joint: an RSA study in human cadaver knees.

The objective of this study was to validate an in vitro human cadaver knee-joint model for the evaluation of the meniscal movement during knee-joint flexion. The question was whether our model showed comparable meniscal displacements to those found in earlier meniscal movement studies in vivo. Furthermore, we determined the influence of tibial torque on the meniscal displacement during knee-joint flexion. Three tantalum beads were inserted in the medial meniscus of six human-cadaver joints. The knee joints were placed and loaded in a loading apparatus, and the movements of the beads were determined by means of RSA during knee-joint flexion and extension with and without internal tibial (IT) and external tibial (ET) torque. During flexion without tibial torque, all menisci moved in posterior and lateral direction. The anterior horn showed significantly greater excursions than the posterior horn in both posterior and lateral direction. Internal tibial torque caused an anterior displacement of the pathway on the tibial plateau. External tibial torque caused a posterior displacement of the pathway. External tibial torque restricted the meniscal displacement during the first 30 degrees of knee-joint flexion. The displacements of the meniscus in this experiment were similar to the displacements described in the in vivo MRI studies. Furthermore, the application of tibial torque confirmed the relative immobility of the posterior horn of the meniscus. During external tibial torque, the posterior displacement of the pathway on the tibial plateau during the first 30 degrees of flexion might be restricted by the attached knee-joint capsule or the femoral condyle. This model revealed representative meniscal displacements during simple knee-joint flexion and also during the outer limits of passive knee-joint motion.

Aged↗
PubMed2004

Computed tomography determined femoral torsion is not accurate.

INTRODUCTION: Computed tomography (CT) is considered the method of choice for detecting rotational malalignment of the femur. However, it is unclear how reliable the method is, and what the causes are of potential inaccuracies. MATERIALS AND METHODS: To address these issues three observers measured the CT images of the femur of 76 patients on two separate occasions. The images were made during follow-up of a unilateral femoral shaft fractures. Rotational malalignment was determined by comparing the torsion angle of the injured to the noninjured leg. RESULTS: The pooled intraobserver variance was 3.9 degrees and interobserver variance 4.1 degrees. Of the two measurements of one observer 95% were up to 10.8 degrees different, and between observers 95% of the measurements were up to 15.6 degrees different. CONCLUSIONS: CT measurements of rotational malalignment of the femur are not accurate. This is due principally to the difficulty in defining a line through the axis of the femoral neck. The accuracy can be improved by taking the average of two measurements.

Bone Malalignment↗
PubMed2004

Prosthetic replacement of the medial meniscus in cadaveric knees: does the prosthesis mimic the functional behavior of the native meniscus?

UNLABELLED: Meniscus replacement by a polymer meniscus prosthesis in dogs resulted in generation of new meniscal tissue. HYPOTHESIS: Optimal functioning of the prosthesis would involve realistic deformation and motion patterns of the prosthesis during knee joint motion. STUDY DESIGN: Controlled laboratory study. METHODS: The movements of the meniscus were determined during knee joint flexion and extension with and without internal and external tibial torque by means of roentgen stereophotogrammetric analysis. Subsequently, the meniscus in 6 human cadaveric knee joints was replaced by a meniscus prosthesis. RESULTS: All different parts of the meniscus showed a posterior displacement during knee joint flexion. The anterior horn was more mobile than the posterior horn. The prosthesis mimicked the movements of the meniscus. However, the excursions of the prosthesis on the tibial plateau were less. The knee joint laxity was not significantly higher after replacement with the meniscus prosthesis. CONCLUSIONS: The prosthesis approximated the behavior of the native meniscus. Improvement in both the gliding characteristics of the prosthetic material and the fixation of the prosthesis may improve the function. CLINICAL RELEVANCE: The meniscus prosthesis needs to be optimized to achieve a better initial function in the knee joint.

Aged↗
PubMed2004

Are surgeons equally satisfied after total knee arthroplasty?

INTRODUCTION: We performed a clinical follow-up study to investigate whether three orthopaedic surgeons were equally satisfied after total knee arthroplasty (TKA). PATIENTS AND METHODS: Thirty-six patients (39 TKAs, mean follow-up 12 months) were reviewed, using the Knee Society Clinical Rating System (KSCRS). For the assessment of satisfaction a visual analogue scale (VAS) was used. RESULTS: We did not find a significant difference in satisfaction between the surgeons. However, there was a significant difference in the knee score and function score of the KSCRS as evaluated by the orthopaedic surgeons (p=0.006 and p=0.04, respectively). The correlation between the knee score and the surgeons' satisfaction was high, which indicates that pain, range of motion and deformity are important success criteria for surgeons. CONCLUSIONS: In this study, surgeons scored differently in the KSCRS but were equally satisfied after TKA.

Adult↗
PubMed2004

Compensation for rotational malalignment after intramedullary nailing for femoral shaft fractures. An analysis by plantar pressure measurements during gait.

INTRODUCTION: Even though rotational malalignment due to a femoral shaft fracture leads to clinical complaints, a large number of patients may have none of significance. The ability to compensate may play a role. The purpose of this study is to give insight into aspects of compensatory gait of patients with a femoral malrotation and the relation with clinical complaints. METHODS: In a cross-sectional laboratory setting, foot-progression angles (FPA) during gait were measured using a foot scan device. Results were related to CT determined femoral torsion and clinical complaints. RESULTS: Patients with external (EMR) or internal malrotation (IMR) showed differences in foot-progression angles (DeltaFPA) in the same direction of their malrotation. Compared to IMR patients, EMR patients appeared to compensate less for their malrotation. No statistically significant differences were detected between these groups for absolute and relative compensation. EMR patients scored worse at the Oxford 12-item and WOMAC score and experienced more problems executing demanding activities than do patients without malrotation. Correlations were found between Oxford 12-item and WOMAC score and relative compensation. CONCLUSIONS: Femoral torsion and the FPA are strongly related. All patients compensate towards normal values of FPA at their fractured side. Patients who are less able to compensate have more physical complaints. EMR patients tend to have more complaints and difficulty compensating.

Adaptation, Physiological↗
PubMed2004

Twist and its effect on ACL graft forces.

Graft tension is a controversial topic in anterior cruciate ligament (ACL) surgery. Evidence suggests a narrow range of graft tensions, which allow the graft to remodel to a stable and mature neoligament. In previous cadaver experiments, we showed that twisting the graft could modulate the graft forces. In this study we hypothesized that the same phenomena would be found in patients, and that twisting the graft intraoperatively can reduce peak forces in the graft. The effects of twist on graft forces in bone-patellar tendon-bone grafts were measured during anterior cruciate ligament surgery on 15 consecutive patients using a custom-made tension-measurement device. Variations in surgical procedure that could potentially affect the graft force patterns were quantified. Graft force as a function of knee-flexion angle was measured with the graft in the neutral, untwisted position and repeated with the tibial bone block rotated externally or internally by 180 degrees. In eight of the 15 knees, external twisting of the graft reduced the maximal graft force to 50%. However, in five knees the forces in extension increased by twisting to a maximum of 300%. Of the surgical variables, only the femoral tunnel position appeared to have a consistent effect on the graft force pattern. Due to the unpredictable effect of graft twisting, a general recommendation on whether the graft should be twisted, and if so, in which direction, cannot be given. Intraoperatively, graft twisting may however be considered in every individual knee to modulate the graft force as a function of flexion angle.

Adolescent↗
PubMed2004

Rotational malalignment after intramedullary nailing of femoral fractures.

OBJECTIVES: Intramedullary nailing has been accepted as the treatment of choice for femoral shaft fractures. The aim of our study was to determine the incidence and implications of rotational malalignment after intramedullary nailing using computed tomography measurements. DESIGN: Cohort study. SETTING: Patients who postoperatively visited the orthopaedic outpatient and radiology clinics. PATIENTS: Seventy-six patients, 59 men and 17 women, with a mean age of 28.4 years (15-88). INTERVENTION: Patients treated on a fracture table with an antegrade reamed AO nail (n = 46) or Grosse Kempf nail (n = 30) for a unilateral femoral shaft fracture between 1988 and 1998 were included in the study. MAIN OUTCOME MEASUREMENTS: Patients filled out a questionnaire concerning pain, daily activities, and sport. Oxford, Western Ontario and McMaster University osteoarthritis index, and Harris Hip and Knee Society scores were obtained. Physical exams and computed tomography measurements were established. RESULTS: Twenty-one patients (28%) were found to have a rotational malalignment of 15degrees or more. There was no significant difference in rotational deformity with either the AO or Grosse Kempf nail. The incidence of malrotation was independent of the fracture level. Patients with a torsional deformity had difficulties with more demanding activities like running, sports, and climbing stairs. Patients with an external rotational malalignment (n = 12) have more functional problems than patients with an internal rotational malalignment (n = 9). Clinically determined rotation differences are not accurate (+/-20degrees) compared with the established computed tomography measurements. CONCLUSIONS: Rotational malalignment after intramedullary nailing for femoral fractures is found in 28% of the patients in this study. These patients have difficulties with more demanding activities, especially when they have an external torsional deformity.

Adolescent↗
PubMed2003

[Limb-length measurements using wooden boards: an accurate and experience-independent method].

OBJECTIVE: To determine the precision and reliability of the indirect limb-length measurement, and the inter-observer variance between doctors differing in level of experience. DESIGN: Descriptive. METHOD: Indirect limb-length measurement by placing 0.5 cm-thick wooden boards under the foot of the shorter leg until the difference in length was corrected, was performed by 3 observers differing in experience (medical student, resident and orthopaedic surgeon) on 66 patients with unilateral femoral-shaft fractures treated with a femoral nail. The group of patients consisted of 51 men and 15 women with a median age of 30 years (range: 18-90). In total 17 observers participated and 177 limb-length measurements were performed. The measurements obtained were compared with limb-length measurements obtained by orthoradiograms of the entire leg. RESULTS: Of the 177 indirect limb-length measurements, 144 (81%) differed by 0-1.0 cm compared with the limb length obtained by orthoradiogram. There was no statistically significant difference in the limb-length measurements obtained by the three groups of observers with different experience levels. There was a certain degree of correlation between values measured by medical students and residents (r = 0.7). When comparing the measurements carried out by staff members with those of residents and medical students, respectively, a lower degree of correlation was found (r = 0.6 and 0.5, respectively). CONCLUSION: Indirect limb-length measurement with wooden boards was accurate. Experience did not play an essential role.

Adolescent↗
PubMed2003

Coordination and stability of one-legged hopping patterns in patients with anterior cruciate ligament reconstruction: preliminary results.

OBJECTIVES: To investigate whether the intralimb coordination of the lower extremity during one-legged hopping in patients with anterior cruciate ligament reconstruction is different and less stable compared to control subjects. DESIGN: Measures of coordination dynamics are applied to study the coordination and stability of movement patterns of the knee and ankle in patients and control subjects. BACKGROUND: Due to several factors, such as loss of proprioceptive function and muscle weakness, the intralimb coordination of the lower extremity might be altered. METHODS: Seven patients and 13 healthy control subjects were instructed to hop in place on one leg for 10 seconds at a comfortable frequency for each leg separately. RESULTS AND CONCLUSIONS: The one-legged hopping movement pattern of patients with anterior cruciate ligament reconstruction one-year post-operative is different and less stable compared to healthy subjects, and thus is still impaired. RELEVANCE: This paper shows that patients, one year after reconstruction of the anterior cruciate ligament, have a different coordination pattern of the lower limb compared to a matched control group. Intersegmental coordination and stability, features that are often observed by eye during a rehabilitation process, are objectified in this study.

Adolescent↗