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Biomedical subjects

J Bellemans

Publications and source records attributed to J Bellemans.

At least 19 recordsLinked to original sources
PubMed2006

A kinematic comparison of fixed- and mobile-bearing knee replacements.

Mobile-bearing posterior-stabilised knee replacements have been developed as an alternative to the standard fixed- and mobile-bearing designs. However, little is known about the in vivo kinematics of this new group of implants. We investigated 31 patients who had undergone a total knee replacement with a similar prosthetic design but with three different options: fixed-bearing posterior cruciate ligament-retaining, fixed-bearing posterior-stabilised and mobile-bearing posterior-stabilised. To do this we used a three-dimensional to two-dimensional model registration technique. Both the fixed- and mobile-bearing posterior-stabilised configurations used the same femoral component. We found that fixed-bearing posterior stabilised and mobile-bearing posterior-stabilised knee replacements demonstrated similar kinematic patterns, with consistent femoral roll-back during flexion. Mobile-bearing posterior-stabilised knee replacements demonstrated greater and more natural internal rotation of the tibia during flexion than fixed-bearing posterior-stabilised designs. Such rotation occurred at the interface between the insert and tibial tray for mobile-bearing posterior-stabilised designs. However, for fixed-bearing posterior-stabilised designs, rotation occurred at the proximal surface of the bearing. Posterior cruciate ligament-retaining knee replacements demonstrated paradoxical sliding forward of the femur. We conclude that mobile-bearing posterior-stabilised knee replacements reproduce internal rotation of the tibia more closely during flexion than fixed-bearing posterior-stabilised designs. Furthermore, mobile-bearing posterior-stabilised knee replacements demonstrate a unidirectional movement which occurs at the upper and lower sides of the mobile insert. The femur moves in an anteroposterior direction on the upper surface of the insert, whereas the movement at the lower surface is pure rotation. Such unidirectional movement may lead to less wear when compared with the multidirectional movement seen in fixed-bearing posterior-stabilised knee replacements, and should be associated with more evenly applied cam-post stresses.

Arthroplasty, Replacement, Knee↗
PubMed2005

Kinematics of posterior cruciate ligament-retaining and -substituting total knee arthroplasty: a prospective randomised outcome study.

We performed a prospective, randomised trial of 44 patients to compare the functional outcomes of a posterior-cruciate-ligament-retaining and posterior-cruciate-ligament-substituting total knee arthroplasty, and to gain a better understanding of the in vivo kinematic behaviour of both devices. At follow-up at five years, no statistically significant differences were found in the clinical outcome measurements for either design. The prevalence of radiolucent lines and the survivorship were the same. In a subgroup of 15 knees, additional image-intensifier analysis in the horizontal and sagittal planes was performed during step-up and lunge activity. Our analysis revealed striking differences. Lunge activity showed a mean posterior displacement of both medial and lateral tibiofemoral contact areas (roll-back) which was greater and more consistent in the cruciate-substituting than in the cruciate-retaining group (medial p < 0.0001, lateral p = 0.011). The amount of posterior displacement could predict the maximum flexion which could be achieved (p = 0.018). Forward displacement of the tibiofemoral contact area in flexion during stair activity was seen more in the cruciate-retaining than in the cruciate-substituting group. This was attributed mainly to insufficiency of the posterior cruciate ligament and partially to that of the anterior cruciate ligament. We concluded that, despite similar clinical outcomes, there are significant kinematic differences between cruciate-retaining and cruciate-substituting arthroplasties.

Aged↗
PubMed2004

The influence of tibial slope on maximal flexion after total knee arthroplasty.

Many surgeons believe that increasing the tibial slope in total knee arthroplasty (TKA) is beneficial with regard to maximal postoperative flexion. Review of the clinical literature, however, does not confirm this hypothesis, neither does it give an answer to the question of how much flexion gain can be expected per degree extra tibial slope. The purpose of this study was, therefore, to evaluate and quantify the influence of tibial slope on maximal postoperative flexion in contemporary posterior cruciate ligament (PCL)-retaining TKA. Twenty-one cadaver simulations of a standard PCL-retaining TKA were studied while reproducing identical deep flexion femorotibial kinematics as documented by three-dimensional computer-aided videofluoroscopy from patients with well-functioning TKAs of the same design. In each knee the tibial component was consecutively implanted with 0 degrees posterior slope, 4 degrees posterior slope, and 7 degrees posterior slope. Maximal flexion was recorded for each configuration. Average maximal flexion at 0 degrees tibial slope was 104 degrees, and increased significantly to 112 degrees when the same knees were implanted with 4 degrees tibial slope. Increasing the slope further to 7 degrees again significantly improved average maximal flexion to 120 degrees. When postoperative radiographic tibial slope was compared to maximal flexion, an average gain of 1.7 degrees flexion for every degree extra tibial slope was noted. Increasing the tibial slope in PCL-retaining TKA does indeed improve maximal flexion before tibial insert impingement occurs against the femoral bone. The surgeon can expect an average gain of 1.7 degrees flexion for every degree extra tibial slope.

Arthroplasty, Replacement, Knee↗
PubMed2004

Restoring the joint line in revision TKA: does it matter?

The importance of joint line restoration in revision TKA is much debated today. This review paper gives an overview of the reasons why joint line elevation occurs so frequently in contemporary revision TKAs, what the theoretical and clinical consequences are of an elevated joint line and how it can be avoided.

Arthroplasty, Replacement, Knee↗
PubMed2003

The effect of exercise regimens on reflex response time of the vasti muscles in patients with anterior knee pain: a prospective randomized intervention study.

The purpose of this prospective randomized intervention study was to evaluate the effect of two exercise protocols on reflex response time of vastus medialis obliquus (VMO), vastus lateralis (VL), in patients with anterior knee pain. Sixty patients were randomized into a 5-week treatment program, which consisted of only open kinetic chain tonification exercises (group I) (n = 30), or only closed kinetic chain tonification exercises (group II) (n = 30). Assessment of an aspect of neuromotor control was obtained by measuring the reflex response times of VMO and VL at the time of initial clinical examination, at the end of the exercise period (five weeks), and three months after the completion of the exercise period. At these evaluation occasions, the intensity and the number of times that the patients experienced anterior knee pain during daily life was recorded on a Visual Analog Scale (VAS). No alterations in reflex response times of VMO and VL were observed in either group. Changes of anterior knee pain over time were statistically significant in both groups. Only small and not statistically supported differences in anterior knee pain were found between the two groups. These results suggest that the reflex response times of the two vasti muscles can not be altered after a five week open or closed kinetic chain exercise program. In contrast, knee pain decreased significantly in both groups.

Exercise Therapy↗
PubMed2002

A correlation study of objective functionality and WOMAC in total knee arthroplasty.

Function studies after total knee arthroplasty (TKA) generally use either self-reported instruments or objective quantitative measurements of walking activities, but it is unclear how objective factors influence self-reports. This retrospective multicenter study assessed the impact of objective variables on subjective self-reported functional outcome after TKA in 128 patients at a mean of 41 months after TKA. Self-reported disability was measured by the Western Ontario and McMaster University (WOMAC) scale, and the quality of walking and representative daily activities were determined objectively by the DynaPort knee test. Objective assessment was found to be a poor predictor of WOMAC abnormality, with correlations of 0.343, 0.246, and 0.269 with WOMAC function, stiffness, and pain, respectively. The results of WOMAC are thus strongly influenced by factors other than quantitative parameters of the lower extremity. These findings provide support for including an objective assessment of activities of daily living together with a subjective self-report.

Activities of Daily Living↗
PubMed2002

Fixation strength of meniscal repair devices.

The aim of this study was to measure and compare the ultimate failure strengths and cyclic fatigue strengths of currently available meniscal suturing devices. No statistically significant difference in failure load was found between a vertical loop suture (mean 46.3 N), a horizontal mattress suture (52.5 N), the T-fix Device (47.5 N), and the 16-mm (39.2 N) and 13-mm (32.8 N) Bionix Arrow. Statistically inferior results were seen with the 10-mm Bionix Arrow (18.8 N), the S.D. Sorb Stapler (4.3 N), and the 12-mm Arthrex Meniscal Dart (10.5 N) (P<0.01). The Mitek Meniscal Repair System (28.1 N) performed intermediate, with significantly better results than the S.D. Sorb Stapler and the 12-mm Arthrex Dart, but significantly worse than the vertical and horizontal sutures, the T-fix and Bionix 16-mm Device (P<0.01). Cyclic fatigue strength was significantly less for the 10-mm Bionix Arrow, the S.D. Sorb Stapler, and the 12-mm Arthrex Meniscal Dart (P<0.01) compared to all other devices. We conclude that the 13- and 16-mm Bionix Arrow and the T-fix Device have comparable ultimate failure strengths and cyclic fatigue strengths to conventional meniscal suturing techniques. The 10-mm Bionix Arrow, S.D. Sorb Stapler, and the 12-mm Arthrex Meniscal Dart, however, have far inferior failure and cyclic fatigue strengths and their clinical application should be questioned.

Equipment Failure Analysis↗
PubMed2002

Which factors predict outcome in the treatment program of anterior knee pain?

The goal of this prospective study was to determine the outcome-predictive role of various parameters in the nonoperative treatment of chronic anterior knee pain patients. Thirty patients followed a five-week treatment program, which consisted out of only closed kinetic chain exercises. Prior to this treatment all subjects were evaluated on muscular characteristics, subjective symptoms, weight, sex, duration of symptoms and functional performance. A multiple stepwise regression analysis revealed that the reflex response time of m. vastus medialis obliquus (VMO) (P=0.041; 0.026), and the duration of symptoms (P=0.019; 0.045) were the only two parameters which were significantly associated with the outcome (evaluated by the Kujala score) at five weeks, and at three months. The shorter the duration of symptoms, or the faster the reflex response time of VMO prior to the treatment, the better the outcome after a closed kinetic chain exercise program. The statistical significance of these parameters in this study may be seen as an indication of the importance of these variables as predictors of the outcome of a closed kinetic chain strengthening program. Using this information, it seems clinically important to begin the treatment program before the anterior knee pain becomes more chronic and treatment results become less good.

Adolescent↗
PubMed2002

Fluoroscopic analysis of the kinematics of deep flexion in total knee arthroplasty. Influence of posterior condylar offset.

Our purpose was to determine the mechanism which allows the maximum knee flexion in vivo after a posterior-cruciate-ligament (PCL)-retaining total knee arthroplasty. Using three-dimensional computer-aided design videofluoroscopy of deep squatting in 29 patients, we determined that in 72% of knees, direct impingement of the tibial insert posteriorly against the back of the femur was the factor responsible for blocking further flexion. In view of this finding we defined a new parameter termed the 'posterior condylar offset'. In 150 consecutive arthroplasties of the knee, the magnitude of posterior condylar offset was found to correlate with the final range of flexion.

Arthroplasty, Replacement, Knee↗
PubMed2001

FDG-PET, 99mtc-HMPAO white blood cell SPET and bone scintigraphy in the evaluation of painful total knee arthroplasties.

Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), technetium-99m hexamethylpropylene amine oxime (HMPAO)-labelled white blood cell (WBC) scintigraphy and bone scintigraphy were used in the evaluation of total knee arthroplasties (TKAs). We prospectively included 21 patients who had a three-phase bone scan for exclusion of infection of TKAs. Four hours after injection of 185 MBq 99mTc-HMPAO-labelled WBCs, planar and single-photon emission tomographic (SPET) imaging was performed. Planar imaging was repeated at 24 h p.i. Consecutively images of the knees were obtained with a dedicated PET system 60 min following the injection of 370 MBq of FDG. Focal tracer uptake was scored on SPET and PET visually (0=no uptake, 4=intense uptake). In addition, SUV (standardised uptake value) per voxel was calculated from attenuation-corrected PET images using the MLAA algorithm. Focal uptake at the bone-prosthesis interface was used as the criterion for infection before and after correlation with the third phase of the bone scan. Final diagnosis was based on operative findings, culture and clinical outcome. In the infected TKAs, the WBC scan showed focal activity of grade 2 (n=2), 3 (n=l) or 4 (n=2). PET scan revealed focal activity of grade 4 (n=5) or 3 (n=1). WBC scan alone had a specificity for infection of 53% [positive predictive value (PPV) 42%, sensitivity 100%], compared with 73% for PET scan (PPV 60%, sensitivity 100%). Considering only lesions at the bone-prosthesis interface that were also present on the third phase of the bone scan, we found a specificity of 93% (PPV 83%) for WBC scan. Using these criteria, a specificity of 80% (PPV 67%) was obtained for PET scan. Two out of three false-positive PET scans were due to loosening of the TKA. It is concluded that WBC scintigraphy in combination with bone scintigraphy has a high specificity in the detection of infected TKAs. FDG-PET seems to offer no additional benefit.

Adult↗
PubMed2001

Patellar tendon vs. doubled semitendinosus and gracilis tendon for anterior cruciate ligament reconstruction.

In a prospective study on ACL reconstruction we treated 17 patients with a "central third-bone-patellar tendon-bone" autograft (PT group) and 32 patients with a doubled semitendinosus/doubled gracilis autograft (HS group). Patients were reviewed at 6 weeks, and at 3, 6, and 12 months postoperatively and the groups compared. Up till 6 months, the KT-1000 side-to-side difference was significantly greater in the HS group (P<0.05) and at 6 and 12 months isokinetic hamstrings strength was lower (P<0.05). No significant differences were noted at any stage with respect to quadriceps strength, functional scores, range of motion, or swelling.

Adolescent↗
PubMed2000

Stress fracture of the inferior and superior pubic ramus in a man with anorexia nervosa and hypogonadism.

The authors present the case of a 23-year-old athlete with a bifocal stress fracture of the pubis. Bifocal cases are rather rare, therefore an insufficiency fracture was suspected. Further investigation showed osteopenia due to secondary hypogonadotropic hypogonadism caused by anorexia nervosa. This case illustrates the need for awareness of underlying metabolic disorders in very rare cases of stress fractures in athletes.

Adult↗
PubMed1999

A modified technique for tibial interference screw fixation of hamstring anterior cruciate ligament grafts.

This article describes a modified technique for tibial fixation of quadrupled hamstring grafts in anterior cruciate ligament reconstruction. Using this technique common problems with tibial interference screw fixation of hamstring grafts-such as loss of tension of the graft during screw introduction or twisting of the graft in the tunnel around the screw-are avoided.

Anterior Cruciate Ligament↗
PubMed1999

Arterial occlusion and thrombus aspiration after total knee arthroplasty.

Arterial occlusion after total knee arthroplasty is an uncommon complication. In the literature only a few cases have been reported, and non consensus exists on the optimal management for this condition. The authors report two patients with popliteal artery thrombosis in the early postoperative period. Both patients were treated with percutaneous thrombus aspiration, a technique that has not been reported previously for this indication. In both patients complete restoration of arterial perfusion and limb salvage was achieved, although ischemic necrosis of the anterior compartment muscles of the lower leg could not be prevented.

Aged↗
PubMed1999

Severe heterotopic ossifications after total knee arthroplasty.

The authors report a case of severe heterotopic ossifications after a total knee arthroplasty in an 83-year-old woman. She showed a dramatic loss in range of motion between the third and sixth postoperative week, after she had obtained a satisfactory 0 degree to 90 degrees--range of motion at the 14th postoperative day. A treatment program of radiotherapy combined with indomethacin and nonaggressive antiinflammatory physiotherapy resulted in a slow but steady improvement with complete relief of symptoms 6 months postoperatively.

Aged↗
PubMed1999

Osseointegration in porous coated knee arthroplasty. The influence of component coating type in sheep.

Although cementless knee arthroplasty is a commonly performed procedure, to date very little was known about the process of osseointegration of knee arthroplasty components. Using a knee prosthesis that was specially designed for the sheep stifle joint, this process of osseointegration could be studied in vivo, together with its effects on clinical and functional performance, its influence on mechanical fixation, and its influence on component stability or migration over time. Additionally, the osseointegration capacity of a newly developed cast mesh porous coating could be examined. The rationale for this newly developed coating was to provide a surface texture with theoretically superior osseointegration capacity, by offering a larger and better controlled pore size, with higher ingrowth area compared to conventional bead type coatings. In summary, the conclusions that are drawn from this work are the following: 1. The degree of osseointegration of knee arthroplasty components is not correlated with clinical and functional performance. Knee arthroplasty components with fibrous integration can function as well as osseointegrated components at least during the first years after implantation. This explains the occasional reports in the literature of post mortem retrieved, well functioning knee arthroplasty components, with purely fibrous integration on histomorphometric analysis. 2. Fibrous integration of tibial knee arthroplasty components, however, leads to less mechanical fixation strength of these components. Osseointegrated components are much more strongly fixed to the underlying bone. This difference in mechanical fixation strength is detectable under physiologic loads. 3. Fibrous integration of tibial knee arthroplasty components leads to increased migration, becoming apparent after 1 year with radiostereometric analysis (RSA). Osseointegrated components are significantly more stable over time. 4. Fibrous integration is less desirable, since it leads to mechanically less rigidly fixed implants, and subsequently to migration over time. On the long-term, fibrous integration might therefore lead to loosening. 5. RSA is an effective tool to assess migration of knee arthroplasty components. The RSA migration of an uncemented component is also an indicator of its degree of osseointegration and its mechanical fixation strength, since RSA migration is correlated with these two parameters. RSA is therefore especially useful during the first postoperative years, since increased migration indicates fibrous integration and low mechanical fixation strength, suggesting an increased risk for subsequent loosening at a later stage. Patients with increased early component migration on RSA might therefore be advised to impose specific restrictions on their knee arthroplasty. 6. Osseointegration is not routinely achieved in conventional porous coated tibial knee arthroplasty components. The development of a theoretically superior cast mesh coating did not lead to a significantly higher degree of osseointegration. It is suggested that the lack of sufficiently small interface gaps and the lack of sufficiently small interface micromotion--two known prerequisites for reliable osseointegration to occur--are the main reasons inhibiting osseointegration, both in this animal model and in the human situation. 7. Significant osseointegration, however, does occur in the newly developed cast mesh coated components, when they are additionally coated with a vacuum plasma sprayed 50 microns hydroxyapatite layer. The newly developed cast mesh coating is ideally suited for such an additional hydroxyapatite coating. Remarkably high percentages of both bone ingrowth and ongrowth can be seen with these hydroxyapatite coated cast mesh coatings, higher than so far reported for current tibial knee arthroplasty components. These osseointegrated hydroxyapatite coated cast mesh components show significantly higher mechanical fixation strength and lower RSA migratio

Animals↗