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P Christel

Publications and source records attributed to P Christel.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1993

[Results of Marshall-MacIntosh reconstruction according to 3 scoring systems (ARPEGE, Lysholm, IKDC). 90 cases reviewed with at least a one-year follow-up].

The "International Knee Documentation Committee" (IKDC) evaluation form was created in 1992 in order to make easier the comparison of the results obtained in the U.S. and Europe in the knee ligament surgery using various procedures. In order to evaluate the performances of the IKDC system, it has been applied to the analysis of the results of 90 Marshall-MacIntosh ACL augmented-reconstructions, all having at least one year follow-up, and compared to the ARPEGE and Lysholm-Tegner systems. All 3 systems have in common a functional activity scale, nevertheless only the IKDC system takes into consideration the ligament examination. In this system, the assessment of the overall result is based on the combination of 4 parameter groups (patient subjective assessment, symptoms, range of motion, ligament examination). The lowest grade within a group determines the group grade. The worst group grade determines the final evaluation. According to the ARPEGE system, 79 per cent of good and excellent results were observed. This percentage increased up to 92.5 per cent with the Lysholm-Tegner system, and up to 82 per cent with the IKDC system. There was a positive and significant correlation between the IKDC system and the two others. The final result, when evaluated with the IKDC system, first depends on the ligament examination, while with the two other systems, pain appears to be the predominant parameter.

Activities of Daily Living↗
PubMed1993

[Total arthroplasty of the hip with a screwed titanium ring cup. Follow-up of 446 prostheses over four years].

The current decrease of total hip arthroplasty using a cemented polyethylene cup point out that bone-cement interface and polyethylene wear are two weak points responsible for long term loosening. Alumina-alumina combination can avoid one of the weak points. But fixing an alumina cup with cement doesn't avoid the second one. So from 1983 we have been using a cup composed by a titanium alloy threaded ring with an alumina insert. From the 508 prosthesis we fixed in between 1983 and 1989, 446 have been followed up over one year with an average follow-up 4 +/- 1.6 years. The patients mean age was 61.7 +/- 12 years. 368 were primary THA performed mostly for osteoarthrosis, 78 were performed in revision cases of cemented cup. All the femoral stems were cemented, we noted only two loosenings. The clinical results were satisfactory in primary arthroplasties (90.7 per cent satisfactory results in the R. Merle d'Aubigné and M. Postel scoring system), whereas in revision cases of cemented cups the percentage of non satisfactory results (32.8 per cent) was very high. Nevertheless migration rate of the threaded rings was 13 per cent (n = 48/368) in primary operation. 8.11 per cent when no structural graft was needed, 22.8 per cent when grafted. Although only 17/48 have been revised up to now, the future of the last 31 remain uncertain. In our opinion, the threaded cup should not be used in revision cases of cemented cups. The long term fixation of a threaded cup remains a problem for the dysplasic acetabula. For the non dysplasic non operated acetabula the migration factors are statistically: female sex, osteoporosis whatever the aetiology, a wrong primary positioning (cup too vertical, protrusio). For all these reasons, from 1989 we have been using a press-fit titanium cup, with promising results.

Adult↗
PubMed1993

[Influence of the suture technique and material on the mechanical behavior of a reinforced Mac Intosh graft].

The anterior cruciate ligament reconstruction by a biological graft augmented by a synthetic device allows theoretically to increase the strength of the composite graft during the remodeling period. The technical realization of the reinforcement is still controversial because it is difficult to obtain a mechanical compromise between a real effect of protection of the graft and a load sharing to favour the remodeling. When the graft and the augmentation device are tied together the ligature between them plays a fundamental mechanical role. The first goal of the present study was to define by calculation and experimentation the influence of the suturing method on the strength of the graft-device ligature. The second goal was to appreciate the possibility of using absorbable suture in such an application. Calculation allowed to show that the weakest area of the composite graft was the junction between the augmented and unaugmented parts of the graft. When increasing number and anchorage of sutures in this critical area it was possible to double the resistance of the ligature. To define the outcome of absorbable suture the strength decrease was measured during the resorption period. Two threads were tested: the polyglactin 910 (Vicryl) and the polydioxanon (PDS). The strength decrease was sudden and rapid for the Vicryl (50 p. cent in 3 weeks). For the PDS the strength loss was more gradual (50 p. cent in 8 weeks). With these two threads the strength duration appeared as incompetent to allow the augmentation to protect the graft during all the remodeling period.

Adult↗
PubMed1993

[Surgical treatment of rupture of the plantar fascia].

Among the various lesions of the hindfoot in athletes, plantar fascia ruptures are not well documented and their surgical treatment is not often reported in the literature. The purpose of the current work was to more precisely define therapeutic indications and to evaluate the results of the surgical treatment based on the excision-release of the plantar fascia. Between 1986 and 1991, 19 patients (5 females, 14 males, average age 32 years) were operated on by one surgeon. All patients were either recreational or competitive athletes. The plantar fascia rupture occurred 18 times during sports activity. Surgical treatment was indicated when pain persisted despite a well conducted conservative treatment. In 17 cases, MRI allowed to plan the operative strategy by showing the fascia lesion. The patients were operated after an average of 8 months following the initial injury (6-16 months). One patient was lost for follow-up, 2 had a follow-up below 6 months, thus 16 patients were available for analysis. The clinical outcome was evaluated through persistence of pain, return to sports, and functional activity. With a 16-month average follow-up (6-51 months) it was observed that pain constantly disappeared and that 11 patients over 16 returned to the same level of sports activity after 6 months with a time-stable result. After failure of a well conducted conservative treatment, surgical treatment of plantar fascia rupture must be proposed. Surgical technique is based not only on fascia release but also on the excision of the pathological scar tissue in order to avoid the restoration of the continuity of the fascia with the calcaneus.

Adult↗
PubMed1992

In vivo degradation of massive poly(alpha-hydroxy acids): validation of in vitro findings.

The degradation of various high-molecular-weight aliphatic polyesters derived from glycolic acid and/or lactic acid enantiomers was previously investigated in vitro. It was demonstrated that the bulk degradation mechanism proposed in the literature actually proceeds heterogeneously and proceeds faster in the centre than at the surface of large specimens. In order to compare them, similar compression-moulded specimens were implanted intramuscularly in the backs of rabbits, namely PLA50 (poly(DL-lactic acid)), PLA37.5GA25 (75% DL-lactide and 25% glycolide in the feed) and PLA75GA25 (75% L-lactide and 25% glycolide). These three intrinsically amorphous compounds exhibited faster central degradation. Furthermore, preferential degradation of glycolic acid units and induced crystallization of L-lactic acid enriched fragments were observed in the case of PLA75GA25. These findings are comparable to phenomena observed in vitro and are conclusively supported by the re-examination of some old in vivo results. Accordingly, data reported in this paper validate both the in vitro modelling and new understanding of the degradation of lactic acid/glycolic acid-based aliphatic polyesters reported previously.

Animals↗
PubMed1992

Ten-year survivorship of cemented ceramic-ceramic total hip prosthesis.

In the first 187 consecutive alumina-alumina combination hip arthroplasties performed from 1977 to 1979, both components were cemented with conventional techniques. At ten-year follow-up evaluation, 87 patients were reviewed or interviewed by telephone, 37 were dead, 39 were lost to follow-up evaluation, and 24 failures were reoperated on before the end of ten years. The major cause of failure was aseptic loosening of the acetabular component (15 failures). Fracture of the socket and of the femoral head occurred in five patients in this series. However, these complications were not seen with components manufactured after 1979. At the end of ten years, survivorship analysis depicted a 82.59% survival rate when reoperation was considered as failure and a 88.57% rate when reoperation for aseptic loosening was considered as failure. The femoral component had a 99.16% survival rate and the acetabular component had an 88.57% survival rate when reoperation for aseptic loosening was considered as failure. Age, appearance of a two- or three-zone demarcation at the intermediate follow-up evaluation, and outer diameter of the acetabular component were the major parameters influencing the results. Better results observed in the population younger than 50 years of age may be related to the small amount of wear debris produced by the alumina-alumina combination. This combination in hip prosthesis is secure, but should be implanted in young and active patients; the outer diameter of the acetabular component must be at least 50 mm. The major problem that remains is the socket's fixation. It could be improved by a design modification, by choosing another mode of fixation, or both.

Aluminum Oxide↗
PubMed1991

[In vitro study of the role of various preservation methods on mechanical properties of allografts of the patellar tendon].

Tendon allografts are presently used for surgical reconstruction of the anterior cruciate ligament. The aim of this study was the in vitro evaluation of the modification of the mechanical properties of conserved human patellar tendons, deep-frozen or freeze-dried and sterilized with gamma rays. Thirty pairs of patellar tendons (central third) with their bony attachments were removed from fresh corpses, frozen in liquid nitrogen, then conserved at -80 degrees C. Out of each pair, one tendon was submitted to an additional treatment and the other was used as a control. Three types of treatment were studied: 2.5 Mrad irradiation (groupe I), freeze-drying with 1% residual humidity (groupe II), consecutive freeze-drying and irradiation (group III). After warming up (controls and group I treated tendons), the specimens were submitted to mechanical tests on the pulling machine with a suitable arrangement. Two types of tests were performed: a creep test (80 cycles at 1 Hz between 0 and 50 N) then an ultimate tensile strength test (0.25 mm/s). Freeze-drying causes macroscopic morphological alterations, which are even more marked if irradiation is applied in addition. The three types of treatment induce an increase in creep and a decrease in the ultimate, tensile strength and in Young's module, all being statistically significant. The three types of treatment alter the mechanical properties of the allograft. Freeze-drying maintains a better resistance of the graft. The combination of freeze-drying and irradiation is the most damaging method, and freeze-drying even seems to potentialize the harmful effects of irradiation resistance (group II freeze-dried grafts), the treated allografts present with changes in their viscoelastic properties that are incompatible with their clinical use. This study has also shown that some parameters influence the extent of the damaging effects of these three treatments, and experiments are being continued to optimize the conservation and sterilization procedure.

Biomechanical Phenomena↗
PubMed1990

[Arthroscopy of the shoulder].

The author describes the techniques currently used in arthroscopy of the shoulder and discusses the diagnostic and therapeutic potentials of this method as well as its complications. Arthroscopy of the shoulder is an interesting alternative to conventional surgery.

Arthroscopy↗
PubMed1990

[The influence of the elasticity module of the femoral shaft and neck of a total hip prosthesis on the distribution of stress in the femur ].

Experiments have shown that stress shielding resulting from implantation of a prosthesis is related to the stiffness of the implant. Stiffness depends on the Young's modulus of the material used and the design of the implant. Most published studies have not attempted to define the relative importance of these two components. We have studied the influence of the elastic modulus only in an experiment using implants of a uniform design. Strain gauges were attached to the calcar in five femurs, three of which also had gauges placed on their medial, lateral and anterior aspects. Surface strain was measured in the intact femur and after implantation of cemented prostheses of the same design but manufactured with or without a collar in stainless steel or titanium alloy. The highest level of calcar strain was recorded with the titanium alloy prosthesis, and the presence of a collar appeared to increase the stress transfer of bone. This effect on stiffness was statistically significant, but was limited to the proximal part of the upper femur. It was not significant in the sub-trochanteric area, due to individual variations in bone geometry and cortical thickness. These results indicate that stress shielding can be directly related to the Young's modulus of the material used, independent of the design of the prosthesis.

Biomechanical Phenomena↗
PubMed1990

The evaluation of cortical bone remodeling with a new ultrasonic technique.

Total hip arthroplasty causes biomechanical changes in the normal femur including a redistribution and concentration of stress. These mechanical alterations in the femur cause local remodeling and resorption that affect the geometry and mechanical properties of the bone. Three complementary techniques were used to study the local adaptive remodeling of bone due to prosthesis implantation. A graphics package was used to obtain section geometrical information, an ultrasonic wave propagation technique to determine elastic properties, and a new scanning acoustic microscope (SAM) to map the acoustic impedance profile of each section. The effects of the implantation of two different types of hip prostheses were investigated, an uncemented bipolar prosthesis with an Austin-Moore type stem and a cemented Charnley prosthesis. Prosthesis implantation resulted in an increase in cortical area and mediolateral diameter and a decrease in anterio-posterior diameter. Both prostheses had a detrimental effect on local elastic properties as determined by acoustic velocity measurements. Finally, the SAM system provided information about local inhomogeneities in bone properties not obtainable by any other means. The acoustic impedance maps highlighted bone resorption and bone remodeling on a microstructural level.

Aged↗
PubMed1990

Alumina-on-alumina hip replacement. Results and survivorship in young patients.

Total hip replacement using an alumina head and socket and a titanium alloy stem is evaluated in a series of patients under 50 years of age. Between April 1977 and December 1986, 86 such replacements were performed in 75 patients, but mainly because patients had difficulty travelling from Africa, only 71 hips were followed up adequately; of these, 56 were primary procedures and 15 revisions. Survivorship analysis showed that 98% of the prostheses were retained for 10 years. On clinical and radiological examination 51 of the 71 hips were stable and acceptable, 15 had radiological changes on the acetabular side, and one on the femoral side; four other cases had clinical and radiological changes suggesting impending failure, possibly because fixation of the socket was inadequate. There were no differences between the results of the primary procedures and those of revisions. In these young patients, the results seem better with alumina-on-alumina hips than with other varieties, possibly because of their remarkably low wear.

Adolescent↗