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Biomedical subjects

P Christel

Publications and source records attributed to P Christel.

At least 19 recordsLinked to original sources
PubMed2002

[Anterior cruciate ligament reconstruction: patellar tendon autograft versus four-strand hamstring tendon autografts. A comparative study at one year follow-up].

PURPOSE OF THE STUDY: The purpose of our study was to compare outcome at one year after anterior cruciate ligament reconstruction for chronic laxity using the patellar tendon autograft or four-strand hamstring tendon autografts. MATERIAL AND METHOD: This non-randomized study included 129 consecutive patients operated on between October 1996 and September 1998. Ninety patients were available for assessment at one year: 50 in the patellar tendon group and 40 in the hamstring tendon group. The two groups were comparable for all criteria except sex. A single operator assessed all patients using the IKDC 93 chart. Laxity was measured by comparison with the healthy knee using the KT1000 at maximal manual tension. Preoperative laxity was 8.0 +/- 3.0 mm in the patellar tendon group and 7.6 +/- 3.0 in the hamstring tendon group. All ligamentoplasties were performed arthroscopically using a blind femoral tunnel. The patellar tendon was fixed with two metallic interference screws and the four-strand hamstring autografts with two different methods: an RCI(R) interference screw or a cortical system associating a femoral Endobutton(R) and tibial fixation with a bicortical tibial screw. Lateral tendonesis was performed with the fascia lata in 60% of the patients in the patellar tendon group and in 45% of those in the hamstring tendon group. Rehabilitation exercises were initiated early and were the same in the two groups. RESULTS: Overall results were satisfactory in more than 80% of the patients in both groups. The final IKDC score was significantly better in the patellar tendon group and subjective patient satisfaction was better in the hamstrings group. Residual pain was significantly less pronounced in the hamstrings tendon group (p=0.004). Laxity was improved significantly better in the patellar tendon group: average residual laxity=2.7 +/- 2.1 mm versus 4.5 +/- 2.8 mm (p=0.03) in the hamstrings tendon group; hard stop at the Lachman test in 96% of the patellar tendon group and 78% in the hamstrings tendon group (p=0.007). Residual laxity was significantly less pronounced in the women in the patellar tendon group. There was no significant difference in laxity by type of fixation in the hamstrings tendon group. Recovery in terms of level of activity and type of sport was the same in the two groups. DISCUSSION: These two surgical techniques provide good functional outcome at one year with better control of laxity with patellar tendon autografts and better relief of pain with four-strand hamstrings autografts. Longer follow-up would be useful to assess laxity long after hamstring reconstruction. We compared the type of transplant and the fixation method together as a single unity, but progress in four-strand hamstring autograft fixation will certainly allow even more optimal results and improved correction of laxity. In our opinion, the patellar tendon autograft remains the gold standard for high-performance athletes practicing a contact-pivot sport, but both types of ACL reconstruction are most useful. We select patients for four-strand hamstring tendon reconstruction as a function of age, sex, and type of sports activities.

Adolescent↗
PubMed2002

[Arthroscopic release for knee joint stiffness after total knee arthroplasty].

PURPOSE OF THE STUDY: Overall, the results of total knee replacement surgery are quite excellent, both with regard to pain and range of motion. Pain relief is obtained in more than 95% of the cases and more than 90% of the patients are able to bend their knee over 90 degrees. Nevertheless, in a small number of cases, stiffness can be an impairment. MATERIAL AND METHODS: Between 1992 and 1998, six arthroscopic releases were performed on six patients who had undergone total knee replacement. The six patients suffered from unacceptable stiffness. The average age of the patients was 68.5 years, and the time elapsed from implantation to arthroscopy averaged 24 months (6 months to 6 years). Average follow-up was 19 months (6 to 96 months). The six stiff knees were treated with arthroscopic debridement of fibrous tissue around the patella and quadriceps tendon (to improve extension) and by arthroscopic division of the medial and lateral retinacula (to address flexion). A gentle manipulation was carried out following lysis of adhesions, using a slight pressure on the tubercle to avoid fractures and disruptions of the extensor mechanisms. Postoperatively, immediate physical therapy was performed including continuous passive motion and active muscular contraction. Early weight bearing was allowed. RESULTS: The average flexion contracture decreased from 9 degrees prior to arthroscopy to 2.5 degrees at last follow-up. Average flexion increased from 70 to 100 degrees. Maximal improvement was obtained at three months. DISCUSSION: Results were found to be quite good, with a final knee score of 93 and a function score of 92 (following International Knee Society scoring). CONCLUSION: Arthroscopic release following total knee replacement complicated by joint stiffness provides a satisfactory increase in range of motion.

Aged↗
PubMed2002

[Anterio-lateral extra-articular tenodesis of the knee using a short strip of fascia lata].

This study describes a lateral extra-articular tenodesis using a short strip of ilio-tibial band. The tenodesis consists of a 12 x 75 mm strip of iliotibial band remaining attached to the Gerdy's tubercle. An isometric point in the region of Krackow's point F-9 is determined with a callipers. The strip of iliotibial band is twisted by 180 degrees to enhance its isometry. Then it is either onlay with a screw and spiked washer on the F-9 point, or within a transverse tunnel drilled through the lateral femoral condyle, from the F-9 point, using and interference screw. Thus, the uses of a short ilio-tibial band tenodesis with a 180 degrees twist in combination with a BPTB reconstruction of the ACL, leads to similar results that the combined classic Lemaire tenodesis, with shorter skin incision, shorter graft harvesting, and at least on the biomechanical standpoint a better graft isometry.

Anterior Cruciate Ligament Injuries↗
PubMed1996

Tibial tunnel enlargement after anterior cruciate ligament reconstruction by autogenous bone-patellar tendon-bone graft.

This retrospective study was designed to evaluate changes in the diameter of the tibial tunnel over time following the reconstruction of the anterior cruciate ligament (ACL) with a bone-patellar tendon-bone autograft in 44 patients. The changes in the geometry of the bone tunnels were measured radiographically during the immediate postoperative period and at time intervals between 3 and 36 months after surgery. The dimensions at 1 year were correlated with the 1-year clinical results. The distance between the sclerotic margins of the tibial tunnel was measured at the distal tunnel exit on the medial tibial cortex, in the middle of the tunnel, and proximally at the level of the joint line. The dimensions were calculated by using a magnification factor determined by reference to the interference screw of known diameter located within the tunnel. The position of the centre of the tibial tunnel with regard to Blumensaat's line was also measured. The average tunnel diameter at the proximal tibial exit increased from 12 +/- 1.9 mm (mean +/- standard deviation) postoperatively to 14 +/- 2.2 mm at 3 months. The average proximal tunnel diameter did not significantly change from 3 months to 2 years, and then decreased to 13 +/- 2.4 mm at 3 years. At 1 year, most of the patterns of osteolysis were of the cone type (57%), followed by the cavity type (40%) and line type (3%). The degree of osteolysis was not related to the tibial tunnel position with respect to Blumensaat's line. There was no correlation between the changes in tunnel diameter and either the IKDC score or the residual joint laxity measured by a KT-100 arthrometer. The aetiology of tunnel enlargement is currently unknown. Possible factors responsible for bone resorption include micromotion of the graft relative to the tunnel wall, leading to an inflammatory response in the tunnel, or stress shielding of the tunnel wall proximal to the interference screw.

Adolescent↗
PubMed1995

Plasma protein adsorption to artificial ligament fibers.

The adsorption of plasma proteins onto biomedical polymers is an important factor in the biocompatibility of biomaterials. We identified the plasma proteins adsorbed onto four polymeric fibers used for synthetic ligament replacement: polyarylamide, polylactic acid, polyester, and polypropylene. The adsorbed proteins were eluted and analyzed by one-dimensional and two-dimensional gel electrophoresis. Fibrinogen, albumin, IgG, high molecular weight kininogen (HMWK), and lipoproteins ApoA-1 and ApoE were the major proteins adsorbed onto polyarylamide. The three others biomaterials bound albumin, fibrinogen, ApoA-1, and ApoE; however, the proportions of proteins bound to each polymer differed. There was an inverse relationship between ApoA-1 and fibrinogen binding for all four biomaterials; polyarylamide bound a high percentage of fibrinogen, but little ApoA-1; polylactic acid, polyester, and polypropylene bound a high percentage of ApoA-1, but little fibrinogen. These results support suggestions that low fibrinogen adsorption might be due to the preferential adsorption of Apo-1. High fibrinogen binding to polyarylamide ligaments may favor fibroblast adherence, growth, and tissue repair.

Adsorption↗
PubMed1995

[Normal and pathological MRI aspects of the posterolateral corner of the knee].

The purpose of the study is to compare normal PLC anatomy and its MRI appearance, with the various lesions observed in MRI, from the simple popliteus tendinous contusion to the complete PLC rupture. For this specific work on PLC lesions, we selected 61 examinations among the traumatic knees explored during the last 3 years. Surgical correlation is obtained for the 61 patients. MRI examinations are performed on a 0.5 T. unit with gradient echo T1, T1 and T1 GD-DOTA IV. Normal PLC anatomy is compared to the dissection of 4 anatomic subjects. Normal MRI slices are evaluated with this reference analysis. The principle anatomical structures of the PLC include the lateral collateral ligament, the popliteus tendon, the arcuate ligament, the fabello fibular ligament, the posterolateral condylar capsule, and the posterior horn of the lateral meniscus. Surgical findings confirm PLC lesion for 58 patients with 3 false positive. Diagnosis of these lesions is important because chronical posterolateral laxity is secondary to the destabilisation of lateral condyle. Unrecognised and untreated posterolateral instability may result in failure of ACL reconstruction. When clinical tests are doubtful or complex, or the examination very painful, MRI evaluates completely the traumatic knee and particularly the PLC.

Humans↗
PubMed1995

[Experimental capsulo-ligamentar lesions of the knee during passive hyperextension. Biomechanical aspects. A lesional evaluation and consequences].

PURPOSE OF THE STUDY: Passive hyperextension is a rare mechanism of injury of knee ligaments in clinical practice. The lesions are often complex and no consensus exists about their sequence. Our purpose was to study the mechanical behavior and the anatomical lesions of the knee following passive hyperextension until rupture. MATERIAL AND METHODS: 12 pairs of fresh human cadaveric knees were tested after resection of soft tissue except for the ligaments and the Popliteus muscle. Some of them had specific ligaments sections (PCL or posterior capsule). We used a "four point bending" model at a constant rate (V = 3 10E-4 m/s) and measured failure torque and bending stiffness of the knee. Results were expressed as percent of the response of the normal contra lateral knee. RESULTS: A wide range of absolute data was noted and correlated to the age and bone quality. Bony avulsion was constant. The posterior capsule was the first structure injured at an average of 23 degrees of recurvatum, followed by the posterolateral ligament. The PCL was the ultimate structure to fail at its femoral attachment, preceding complete dislocation of the knee. No ruptures of the ACL and medial collateral ligament were noted. After section of the posterior capsule, the stiffness of the knee decreased 40 to 80 percent compared to the normal opposite knee, whereas the isolated section of the PCL had no significant effect. DISCUSSION: The method used in this study appears reliable. "The four point bending" is a reproducible model and the use of paired specimens allows a quantitative approach. The use of elderly specimens at a low strain rate in this experiment remains a questionable point. Passive hyperextension is characterized by automatic external rotation resulting in asymmetrical posterior lesions and tears of the PCL at its femoral attachment. On the contrary, active hyperextension of the knee can produce ACL injury by anterior translation of the tibia under the femur consecutive to Quadriceps femoris contraction. CONCLUSION: Our experimental model is an effective and reproducible method to create passive hyperextension of the knee. The first structure to fail is the posterior capsule followed by the posterolateral ligament. The PCL is the ultimate structure to fail and no ACL rupture has been noted before dislocation. CLINICAL RELEVANCE: if passive hyperextension mechanism is suspected, isolated posterior capsule lesion may occur and should be repaired. On the contrary, PCL tear should never be isolated and always associated with peripheral ligament injuries.

Anterior Cruciate Ligament↗
PubMed1994

Analysis of the general features of the soft tissue response to some metals and ceramics using quantitative histomorphometry.

This article analyzes the general features of the tissue response to orthopedic biomaterials when implanted in the paraspinal muscles in rats for periods between 1 week and 1 year. Using a computer-assisted cell counting method, it was shown that the membrane thickness was a stable parameter that poorly correlated with the other histomorphometric parameters except fibrocyte distance parameters. Macrophages were significant in number only in the short term and were always located at the implant-tissue interface. At 4 weeks, the period corresponding to which macrophages disappeared, fibrocytes were found nearer the interface than at earlier periods and did not migrate for up to 52 weeks, although their densities decreased to 50% of their initial values. Therefore, it can be histomorphometrically confirmed that 1) the presence of an implant induced a delay in the healing process; 2) the immune system was not usually involved in the response to bulk metals; and 3) at early time periods, the presence of PMN cells was correlated to the long-term number of macrophages. On the contrary, the histomorphometric findings suggested that around the tested materials, a large number of macrophages did not induce an immediate or a delayed fibrocyte proliferation. If one considers that a low fibrocyte surface density is related to activated cells surrounded by a matrix high in collagen content, then the large number of macrophages induced the stimulation of collagen synthesis by the fibrocytes already included in the membrane. Accordingly, in the short-term, a high fibrocyte density and few macrophages may be a criterion for testing biocompatibility.

Animals↗
PubMed1994

Formation of a calcium phosphate-rich layer on absorbable calcium carbonate bone graft substitutes.

The use of natural coral as a bone graft substitute is common in Europe. However, the bone-coral bonding mechanism remains elusive. A rat subcutaneous model was used to demonstrate changes at the surface of resorbable calcium carbonate in the form of natural coral. Histological results indicated in vivo formation of a calcium phosphate (CaP)-rich layer on the surface of the coral confirmed by backscattered electron imaging and X-ray microanalysis. There appears to be a combination solution-mediated dissolution/cell-mediated degradation of the natural coral with subsequent surface conversion or precipitation. The end result is a CaP-rich layer on the coral. Though this layer has been observed previously, it was originally thought to be a histological artifact. This result is similar, however, to what is seen with Bioglass and glass ceramics and may also explain the good bonding of bone to hydroxyapatite. The fact that this layer is also present on natural coral after implantation in soft tissue sites may explain the intimate bone apposition observed when natural coral is placed in bony sites.

Absorption↗
PubMed1994

Roentgenographic and magnetic resonance imaging of anterior cruciate reconstruction using a patellar tendon graft--correlations with physical findings.

The purpose of this study was to evaluate the influence of the graft positioning on the clinical outcome and magnetic resonance imaging (MRI) signal of the graft following anterior cruciate ligament (ACL) reconstruction using the central one-third of the patellar tendon. Twenty-two patients with a chronic anterior instability underwent a modified Marshall-MacIntosh procedure, while 27 with a subacute torn ACL had an ACL reconstruction using a free bone-patellar tendon-bone graft. The patients were retrospectively reviewed with a 1.8-year average follow-up (1-3 years). The clinical result was evaluated through the comparative range of motion and the residual laxity as measured with the KT 1,000 arthrometer. The roentgenographic analysis was performed from anteroposterior (AP) and mediolateral (ML) views, made first on one-leg standing with the knee at 30 degrees of flexion, and secondly at "zero" extension with active quadriceps contraction. Lines were drawn to visualise the location of the tibial and femoral tunnels in relation to the tibial plateaus and the intercondylar roof represented by Blumensaat's line. The analysis of the lateral MRI views of the graft allowed discrimination between homogenous and heterogenous graft signals. On lateral roentgenograms of normal knees, it was found that Blumensaat's line crossed the surface of the medial tibial plateau at 30% +/- 9% of its sagittal width (20%-40% range), demonstrating the variability of intercondylar roof inclination. The range of motion was normal in 34 patients (group I), 9 patients had a flexion deficit (group II), and 6 exhibited an extension deficit (group III). The residual laxity was similar in each group (P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior Cruciate Ligament↗
PubMed1994

Prosthetic replacement of the anterior cruciate ligament: a challenge.

Replacing the chronic deficient anterior cruciate ligament (ACL) has been demonstrated to be a challenging surgical procedure. ACL anatomy and structure as well as its biomechanics have been extensively studied in order to understand its properties and improve its reconstruction. Currently the ACL may be replaced by different means. Autogenous grafts, allografts (augmented or not) and prosthetic devices are available. Each method exhibits inherent advantages and drawbacks which are critically reviewed. If one considers the method of choice as the use of the middle third of the patellar tendon, there is no good evidence that prosthetic augmentation of autogenous grafts offers any advantage over autogenous grafts by themselves. The currently available prosthetic ligaments break and generate debris which are responsible for synovitis. Further development of new devices more closely duplicating the biomechanical features of ACL is necessary.

Anterior Cruciate Ligament↗
PubMed1994

Functional evaluation of polyarylamide fibers for use in a prosthesis for anterior cruciate ligament replacement in the sheep.

In order to evaluate the potential use of polyarylamide fibers as a prosthetic material for ligament replacement, resected sheep anterior cruciate ligaments were replaced by braided devices routed through a tibial tunnel and over the top of the lateral femoral condyle. Twelve sheep were used and sacrificed between 3 and 12 months. The tissue response to the implant was evaluated histologically. Morphologic features of the fibers and the abraded particles were measured by image analysis. Simultaneously, the tensile properties as well as the creep and fatigue properties of non-implanted prostheses were measured under laboratory conditions. It was shown that the polyarylamide fibers exhibited high strength, a high modulus, but low fatigue abrasion properties. At autopsy, 1 prosthesis was broken, 6 had frayed and 5 were intact. There was no adverse tissue response to the intact fibers. Inflammation was always linked to the presence of polymeric particles. A large bony ingrowth in the tibial tunnel through the prostheses strands was observed. There was no material resorption throughout the experiment. Polyarylamide fibers appear to be a suitable material for ligament replacement provided that abrasion against bone can be avoided.

Amides↗
PubMed1994

Recent advances in adult hip joint surgery.

This article is a summary of the information published in the field of hip surgery in adults over the past year. It reviews the epidemiology and economic aspects of total hip replacement, which dominates adult hip surgery, and examines the long-term results and complications that occur with both cemented and uncemented arthroplasty of the hip. Aseptic loosening is a major problem in the long-term outcome of total hip replacement. Wear of the bearings with production of particulate debris induces a local inflammatory response, activating the bone resorbing cells. Accordingly, revision surgery has become a frequent procedure that raises difficult problems. Strategy, methods, implant design, grafting, and indication for cemented or noncemented total hip replacements are discussed.

Adult↗
PubMed1994

[Radiologic and MRI evaluation of intra-articular ligamentoplasty using a patellar tendon. Correlations with anatomical results].

INTRODUCTION: the purpose of this study was to evaluate the influence of the graft positioning on the clinical outcome and MRI signal of the graft as well, following ACL reconstruction using the central one-third of the patellar tendon. MATERIAL AND METHODS: twenty one patients having a chronic anterior instability sustained a modified Marshall-Mac Intosh procedure, while 15 having a subacute torn ACL had an ACL reconstruction using a free bone-patellar tendon-bone graft. The patients were retrospectively reviewed with a 1.8 year average follow-up (1-3 years). The clinical result was evaluated through the comparative range of motion, the residual laxity as measured with the KT 1000 arthrometer, and the pivot shift test. The roentgenographic analysis was performed from AP and ML views, made first on one-leg standing with the knee at 30 degrees of flexion, and then in "zero" extension with active quadriceps contraction. Lines were drawn to visualise the location of the tibial and femoral tunnels in relation to the tibial plateaus and the roof of the intercondylar notch represented by the Blumensaat line. The analysis of the AP IRM views of the graft allowed to discriminate between homogeneous and heterogeneous graft signals. RESULTS: on lateral roentgenograms of normal knees it was found that the Blumensaat line crossed the surface of the medial tibial plateau at its anterior third, at 30 +/- 9 per cent (20-40 per cent range), demonstrating the variability of the intercondylar roof inclination. The range of motion was normal in 22 patients (group 1), 8 patients had a flexion deficit (group II), and 6 exhibited an extension deficit (group III). The residual laxity was similar in each group (p > 0.05). When comparing group III to group I, patients from group III had a tibial tunnel significantly more anterior with regard to the Blumensaat line (p < 0.02). In group III, all patients exhibited an heterogeneous MRI graft signal (p < 0.05), and the angle between the intraarticular part of the graft and the tibial tunnel was higher (p < 0.001). These findings were not observed in group II where the location only of the femoral tunnel seemed to influence the flexion deficit (p > 0.05). DISCUSSION AND CONCLUSION: this study demonstrated that the location of the tibial tunnel with regard to the roof of the intercondylar notch, when the knee is in "zero" extension, was the most relevant parameter controlling the extension deficit resulting from a graft impingement. No relation was found between the tibial tunnel location with regard to the tibial plateaus and the mobility deficit. Graft impingement also was always associated with an heterogenous graft MRI signal. CLINICAL RELEVANCE: when reconstructing the ACL care must be taken when inserting the K-wire aimed to guide the tibial drill, to obtain a proper position with regard to the roof of the intercondylar notch. The K-wire location must be checked in "zero" extension. Intra-operative X-rays may help.

Anterior Cruciate Ligament↗
PubMed1993

[Principles and value of isokinetic evaluation in ruptures of the anterior cruciate ligament].

Isokinetic muscular evaluation allows to appreciate the knee joint functional patterns in conditions close to sports activities. Analyzing bilateral symmetry and agonist/antagonist ratios of the lower extremity, this method is a useful index for the objective evaluation of ligament-deficient knees. 106 patients with a chronic ACL deficient knee sustained a presurgery isokinetic evaluation. 94 patients had a post-operative evaluation and 13 a pre and post-surgery evaluation. All patients were simultaneously evaluated by clinical examination and measures of instrumental knee laxity (KT 1000). Results showed that isokinetic performance was not correlated to the objective laxity as measured with the KT 1000 but was correlated to 1) the type of laxity (i.e. associated postero-lateral laxity), 2) the functional level of activity, and 3) the time of disability. Best functional results were obtained in patients whose injured knee hamstring/quadriceps (H/Q) ratio was close to the uninjured knee H/Q ratio. The mean quadriceps deficit was over 15 per cent for 75 per cent of the patients one year after surgery, and for 50 per cent of the patients after two years. The quadriceps deficit was not parallel to the length of the autograft taken from the extensor mechanism. Isokinetic evaluation is a guideline for rehabilitation allowing specific strengthening of the weaker muscular groups.

Anterior Cruciate Ligament↗