Satisfactory long-term MRI after autologous chondrocyte implantation at the knee.

PURPOSE: Autologous chondrocyte implantation (ACI) to address isolated condylar lesions is supposed to limit degenerative deterioration in neutrally aligned knees. Here, we report long-term results of the first-generation ACI technique with periosteal flap. METHODS: Twelve patients, 29 years old on average, were included on the basis of pre-operative MRI selection of lesions >2 cm2. Cartilage carrots were harvested arthroscopically, then cultured and finally re-implanted within a mean time interval of 12 weeks. Ten-year MRI results were analysed according to a semi-quantitative scale, along with functional assessment based on International Knee Documentation Committee score, Lysholm et al. score and the Tegner et al. activity scale. RESULTS: One patient secondarily required valgus tibial osteotomy with mosaic plasty. Another incurred graft hypertrophy that necessitated arthroscopic peeling. MRI showed that cartilage repair filled more than 50% of the initial defect in 9 patients. Standard radiographs revealed slight narrowing of the joint line. Overall, functional scores improved durably by 50%, although activity level decreased substantially. CONCLUSION: ACI contained degenerative changes within moderate stages while maintaining durable functional improvement. However, in the absence of controls, it was difficult to differentiate between these findings and the spontaneous evolution of non-treated lesions. LEVEL OF EVIDENCE: Case series, Level IV.

Multicenter-study of operative treatment of intraligamentous tears of the anterior cruciate ligament in children and adolescents: comparison of four different techniques.

Tears of the anterior cruciate ligament in skeletally immature patients were operated with four different methods and their outcome compared to each other. Sixty-eight patients (33 males, 35 females), mean 12.5 years, were treated in four different centers from 1984 to 2001. Twenty-eight patients underwent the ACL-reconstruction with hamstring grafts, 16 patients with bone-patella-bone autografts, 12 patients with quadriceps grafts and 12 patients with facia lata. The mean follow-up was 32 months. Postoperative evaluation included radiographs, KT-1000/2000 stability measurements, Lysholm score, The Tegner activity scale and IKDC score. Neither leg length discrepancy nor angular deformities were noted. Mean KT-1000 difference was 2.1 mm, mean postoperative Lysholm knee score 93.3, IKDC 87% normal or nearly normal. The Tegner index decreased from 6.6 to 5.7. In total, six patients developed instability due to an adequate trauma 1 year after the index operation. Two patients showed mild arthrotic changes. All but two patients were able to return to the same level of preoperative sports participation. None of the four methods studied showed major differences in outcome compared to the other. No growth disturbance could be noted.

Elevation of the tibial tubercle for patellofemoral pain syndrome. An 8- to 15-year follow-up.

One hundred patients were operated on by the Maquet procedure for chondromalacia patellae. All of them were first re-examined after a mean follow-up of 4 years, and 65 of them re-examined after a mean follow-up of 11 years (range, 8-15 years). The pain score improved significantly after the operation and remained unchanged with longer follow-up. The success rate was only 62% at both follow-ups. Outerbridge grade IV chondral lesions at the time of surgery were associated with a significant improvement of the pain score at the 4-year follow-up and a success rate of 69%. The Maquet procedure should only be proposed for chronic retropatellar pain with grade IV chondral lesions, after conservative treatment has proven unsuccessful, as the expected failure rate is about 30%.

[Macroscopic, histologic and ultrastructural study of 89 prostheses of anterior cruciate ligament excised because of prosthesis failure]. / Etude macroscopique, histologique et ultrastructurale de 89 prothèses du ligament croisé antérieur explantées pour échec.

PURPOSE OF THE STUDY: This study concerns the etiology of failed synthetic anterior cruciate ligament (ACL) prostheses, and attempts to identify the primary mechanisms that lead to their premature rupture. MATERIAL AND METHODS: A total of 89 failed and surgically excised ACL prostheses were retrieved from young and active patients (27 +/- 7 years) at various orthopaedic centres in France. Their average duration of implantation was 34 +/- 24 months. They were examined macroscopically, histologically and by scanning electron microscopy (SEM) to determine the model, the manufacturer, the surgical technique used at implantation, the extent of healing, the site of rupture, as well as the morphology of the damage fibers. RESULTS: Seventy two of these explants represented 6 different models. While all 6 were fabricated from polyester fibres, each had a different textile construction, and each were associated with a unique healing and mechanical response in vivo. SEM observations confirmed that abrasion of the textile fibres were a phenomenon common to all models, and were the primary cause of prosthesis failure. Such wear zones were particularly prevalent at the exit of the tibial tunnel and around the femoral condyle. Collagenic infiltration into the synthetic ACL was poorly organized and unpredictable. It did not increase with the duration of implantation. In fact in certain models, it appeared to have caused deterioration and fraying of the textile structure rather than serving as a reinforcing matrix around the prosthesis. DISCUSSION: A synthetic ACL prosthesis is to be preferred for patients who do not have tissue available for autologous ligamentoplasty. Yet none of the synthetic devices examined in the present study were capable of stabilizing the knee over the long term. Among the factors that influenced their failure we found that the three most common mechanisms were flat abrasion against an osseous surface, flexural and rotational fatigue of the fibres, and loss of integrity of the textile structure due to unpredictable tissue infiltration during healing. CONCLUSION: The results of the present study show that none of the current models succeed in replacing the natural ACL. Future improvements may be achieved by developing surgical procedures for implantation combined with a prosthesis made from fibres and textile structures which are more abrasion resistant and promote predictable and controlled tissue infiltration.

[Ender nail with interlocking mechanism or dynamic hip screw in pertrochanteric fractures? A prospective study extending its limits]. / Ender-Nagel mit Verriegelung oder dynamische Hüftschraube bei pertrochantären Frakturen? Eine prospektive, grenzüberschreitende Studie.

In a prospective study on 148 patients with trochanteric fractures of the hip we compared the results of two implant-systems: the Ender-nailing modified by the dynamical interlocking method of Kempf and Bitar, and the dynamic hip screw (DHS) of the AO-ASIF. The Ender-method had the shorter operation time, earlier weight-bearing and less septic complications. Fracture consolidation was complete after three months in all cases. But in 8% reosteosynthesis because of hip joint perforations of nails was necessary. The method leads in less cases to anatomical reduction (85%), more often relevant varus (9%) and rotationary (14%) malpositions and functional deficits in hip (25%) and knee joints (9%), compared with the DHS. The DHS had less implant complications, reosteosynthesis was necessary in 4%. Technical failures were seldom. In 96% anatomical reduction could be achieved and the function of the hip was in 87% good to excellent. The Ender-nailing with dynamic interlocking is a system for internal fixation of trochanteric fractures in elder patients. The DHS-system has better functional results. Both systems need to be performed in a very careful, exact surgical procedure, to avoid complications.

[Superselective angiography of the circumflex arteries in preoperative evaluation of femoral neck fractures]. / L'angiographie supersélective des artéres circonflexes dans l'evaluation pré-opératoire des fractures du col fémoral.

The study of arterial vascularity in the head and neck of the femur is performed as an emergency exploration of femoral neck fractures by means of selective catheterization. The systematization of vascular lesions thus obtained is compared with the anatomical types of fractures. The posteromedial circumflex artery is not injured definitively as a rule, so that conservative osteosynthesis can be preferred to arthroplasty.

The three-dimensional active rotary stabilization of the knee.

The careful examination of insertions and directions of the tendons of the knee peri-articular muscles permits a global conception of the action of the 29 couples in rotatory stabilization. First, an analytic study of the tibial and femoral rotatory stabilization is considered. Second, the three-dimensional rotatory mechanical coupling between femur and tibia is developed. The anatomical complexity of the musculotendinous elements allows understanding of the risks of desynchronisation of the articular joint in case of lesion of the central ligament pivot.

[The mechanical properties of devices used for the fixation of femoral neck fractures (author's transl)]. / Aspects mécaniques de l'ostéosynthèse des fractures du col du fémur. Etude comprative des différents moyens d'ostéosynthèse.

The authors have studied the mechanical problems of internal fixation of femoral neck fractures, both from the theoretical and experimental point of view. They have tested stability of several types of fixation according to the obliquity of the fracture line. Three types of strain have been applied to fractured dried bone. Fixation by three parallel screws seemed to give the most stability. The authors conclude that, with this type of fixation, early weight-bearing can be resumed by patients with fractures of Pauwels type I and II, but weight-bearing is still dangerous in type III.

Fatigue - corrosion of endoprosthesis titanium alloys.

Commercial total hip prostheses often show certain metallurgical faults (porosities, coarse grains, growth dendrites, carbide networks). In order to investigate more accurately the role played by these different parameters in prostheses failure we performed a large number of systematic corrosion, fatigue and fatigue - corrosion tests on these materials and on commercial total hip prostheses. Ultimate strengthes seem to be reached for cast cobalt alloys, whereas titanium alloys, such as Ta 6 V, present very high fatigue limit under corrosion. Thus, rotative bending fatigue - corrosion tests in biological environment provide values about 50 DaN/mm2. This value, is nevertheless appreciably higher than those obtained with stellites and stainless steel. Titanium alloys, because of their mechanical performances, their weak Young's modulus (11000 DaN/mm2) and their relative lightness (4.5. g/cm3), which are associated with a good biocompatibility, seem very promising for permanent implants realisation.

Bone bonding through bioadhesives: present status.

Until recently use of adhesives was confined to cases in which glued areas could be pre-treated or at least cleaned. Thus, grease or oil contaminated surfaces could not be joined together by glueing. More recently, some adhesives have been developed which allow previous treatment of greasy surfaces to be avoided. Among these we find epoxy resins, acrylics and polyurethances. These adhesives have been used until now in various industries. We have begun a research program with these products and in aiming to design an adhesive which would enable immediate and strong bone bonding and avoid problems of metallic fixation, this study is a continuation of our previous research. Thus we tested - currently available surgical and dental adhesives - original mixtures developed in our laboratory. Mechanical assays were performed on bone samples from human femurs in different conditions : dried, cleaned, fresh, or after immersion in physiological solution. They consist essentially of tensile tests on Lhomargy and Zwick's machine wherein the stress is directed perpendicular to the interface. Variations of tensile strength (in h bar) are related to hardening time and to mixture composition. The specimens are joined together either in monolayers or in multilayers. The use of adequate catalysts ensures setting at room temperature. Torsion tests and fatigue tests are carried out concomitantly. Standardized bevel fermoral osteotomies were performed on mice with a dental saw after I.P. Nembutal anesthesia in order to test biological tolerance : - for the control group we study the evolution of bone repair after circumferential wiring - for the animals under test, bones are glued together with one of the proposed adhesives. Radiological and histological studies (using classical Azantrichrome staining after demineralization) are carried out at regular time intervals. In the control animals particular attention is paid to the time course of the formation, constitution and evolution of callus. In the test animals, we can observe callus formation, bone growth into the adhesive material and glue resorption, and look for specific antigenic phenomena. Despite expected improvements, bone glueing remains a challenge and only restricted clinical applications can be proposed.

[Intramedullary nailing with reaming. A critical analysis of Kuntscher's principle (author's transl)]. / L'enclouage centro-médullaire avec alésage. Critique théorique et expérimentale des principes de Kuntscher.

The authors have reviewed two of Kuntscher's principles relating to intramedullary nailing: the moment of elasticity of the nail should be close to the moment of elasticity of the bone and the suppression of rotation movements at the fracture site is due to locking of the nail by virtue of its elasticity. They have conducted an experimental study which does not confirm these views. They considered that rotary stability is due to muscle tone, the line of the fracture and the anchorage of the ends of the nail at the upper and lower end of the bone.