Alloplastic replacement of the anterior cruciate ligament in chronic instability--indications and technic

Since August 1980, missing or no longer present cruciate ligament structures have been replaced in many patients suffering from chronic instability of knee-joint ligaments, by an implanted ligament made from Trevira hochfest. 158 operations of this kind were supervised by the author. Although results have been good so far, the indication for such an operation should be extremely restricted. The isolated replacement of the anterior cruciate ligaments in chronic instability is an ideal application field. Detailed attention is given to the implantation technique aiming at restoring permanent stability.     

Alloplastic replacement of the anterior cruciate ligament. Material technical and biomechanical principles, surgical technique]

The Trevira-ligament of Polyaethylenter-ephthalat (= Trevira-hochfest 730) seems to be the best qualified replacement of the anterior cruciate ligament at the present. It meets all material and technical requirements and makes allowances for all biomechanical knowledges. The modified over-the-top-technique by arthroscopy or mini-arthrotomy (minimal operative trauma) makes it possible to conserve still existing ligamentous and soft tissue and guarantees the post-operative immediate functional therapy. A potential reinstability--independent of each cause--doesn't imply worse starting conditions and enables corrections including the substitute of a ruptured synthetic ligament.     

Experimental replacement of the anterior cruciate ligament. A histological and microradiographic study.

In each of four dogs, teno-osseous autogenous grafts were used to reconstruct the anterior cruciate ligament. The transplanted strips first underwent ischemia and cellular death, with necrosis of both bone and tendon. Ingrowth of tissues then occurred rapidly, but complete incorporation of the tendon or the bone did not occur at one year. However, the tunnel-to transplant bone was functional and provided sufficient stability to the knee so that disruption of the reconstructed anterior cruciate ligament did not occur.     

Cruciate ligament replacement using a meniscus. An experimental study

In 30 rabbits, the medial meniscus was used to replace the anterior or posterior cruciate ligament. The changes that took place were followed in histological sections, obtained both from the area of insertion into bone and from the intra-articular part of the graft. There was a gradual differentiation to chondroid tissue, with subsequent calcific deposition and no appearance of normal ligamentous tissue. The strength of the graft after 52 weeks was only one-quarter of that of the normal ligament. Our results do not justify the use of the meniscus to replace a torn cruciate ligament.     

Alloplastic treatment of knee ligaments. Experience using artificial support in fresh injuries of the inner ligament

From November 1983 to July 1985 a plastic reinforcement of the collateral medial ligament was performed in 14 patients. In all cases there was an additional reconstruction of the anterior cruciate ligament and a partial resection respectively refixation of the medial meniscus. In order to confirm the collateral ligament alloplastically in 6 cases a non-resorbable plastic connection (Gore-Tex patch), in 8 cases a resorbable plastic connection (PDS) was used. All the patients could be clinically reinvestigated on an average of 13 months after the operation. The results are presented.     

Segmental spinal instrumentation. A study of the mechanical properties of materials used for sublaminar fixation

Segmental spinal instrumentation with sublaminar fixation is widely used but a variety of materials and techniques are being employed for both scoliosis and other spinal surgery. This study addresses the question as to which is best. Both the materials and the methods of securing them were studied. The materials tested were stainless steel 316L, Ortron 90 high nitrogen steel, titanium alloys, nylon straps, and Mersilene tapes. Doubled cold-worked 00.84-mm diameter stainless steel formed in a knot with a twist proved to be the strongest and most secure means of fixation with a yield value of 1,610 N. Attention to the details of technique and material such as the incorporation of a secondary twist and avoidance of hot-worked stainless steel may reduce the incidence of implant failure.     

Alloplastic replacement of the partially resected canine urethra by expanded polytetrafluoroethylene grafts

Summary In 12 male dogs 3–8 cm of the penile urethra were resected and replaced by expanded polytetrafluoroethylene (GORE-TEX^®) grafts. Follow-up consisted of periodic urethrograms. Maximum observation time has been 12 months. Up to now, no major complications were noted. Tissue reactions were minimal and patency of all grafts was demonstrated during the follow-up period.     

Arthroscopic and clinical evaluation after isolated, augmented anterior cruciate ligament replacement. A prospective study

80 patients were examined in to perform a prospective essay on the isolated substitute of the anterior crucial ligament being done by Miniarthrotomie and two channel technique. All patients received a substitute of the anterior cruciate ligament by using an autogenous, TETRA-L3 augmentated bone tendon bone graft from the middle third of the patellar ligament of the injured knee. Clinical and arthroscopical examination was carried out in the average 28 months (24-36) after crucial ligament reconstruction, by the routinely removal of the augmentation and fixation material. Clinical examination was carried out using the strict and objective IKDC-Score. The arthroscopical evaluation of the ACL-graft was performed with our recently developed Score for ACL-graft evaluation (Marburger Arthroscopy Score for graft evaluation). The Score distinguishes between four stages: type I: tight, crucial ligament like structured graft, type II: a firm, more bundle like structured graft, type III: a lax, untidy structured graft and type IV: the rudimentary graft. A statistical analysis was performed on the question whether there is a correlation between the clinical and the arthroscopical results. Furthermore, with the Marbuger Arthroscopy Score for graft Evaluation we introduced a standardised, simple-to-use new score for the arthroscopical ACL-graft evaluation. We find a high correlation (r = 0.77) between the clinical results and the arthroscopical findings, so that from clinical evaluation there might be draw conclusion to the arthroscopical expective results with high probability. Due to our previous experience we assume the Marburger Arthroscopy Score For Graft Evaluation to be a standardised and simple assessment method for the evaluation of the ACL-graft, considering pathobiomechanical influences on the ACL-substitute.     

Healing phases in autogenous posterior cruciate ligament replacement. A decision aid for after-care. A biomechanical and histologic study

In a sheep model for reconstruction of the posterior cruciate ligament using the central one-third of the autogenous patellar tendon and immediate mobilization, the incorporation course was studied biomechanically, histomorphometrically and radiographically at eight different points in time up to 1 year after surgery. Four different phases of autograft healing were demonstrated on the basis of the histological events. The biomechanical data were correlated with the morphological findings. Phase 1--necrosis--was characterized by a maximum of necrotic autograft tissue 2 weeks postoperatively. Initially, graft strength was determined by the surgical fixation strength. During phase 2--revitalization--the autograft showed cellular proliferation and revascularization, starting from the periphery. The autograft was determined to be weakest during this phase. Phase 3--collagen formation--revealed a marked increase in newly formed collagen tissue between weeks 12 and 16. A significant increase in maximum load and stress was measured. In phase 4--remodeling--the longest phase, the collagen tissue appeared more compact and less cellular. The fiber bundles were arranged more longitudinally. However, the biomechanical properties remained clearly below that of a normal posterior cruciate ligament.     

Early results of the Leeds-Keio anterior cruciate ligament replacement.

We report the two- to four-year results following the insertion of the Leeds-Keio prosthetic ligament for chronic anterior cruciate deficiency. Virtually all the 20 patients were less disabled by instability, but objective results were good or excellent in only two-thirds and under anaesthesia the pivot shift sign was still positive in half. Arthroscopic and histological assessment in 16 patients failed to show the development of a functional neoligament, and the common appearance of a synovitic reaction to polyester particles gave concern.     

Cementless acetabular replacement in the young. A 5- to 10-year prospective study

This article presents a prospective clinical and radiologic review of 55 total hip replacements in 50 patients in which the cementless Harris-Galante porous-coated acetabular component was used. All patients were 50 years of age or younger. The cups were inserted by 15 different surgeons. The minimum followup was 5 years, with a mean of 7 years. No acetabular component has been revised for loosening, and none have migrated. Three (5.5%) cups have progressive bone-component radiolucent lines, two (3.6%) of which are complete. Six (10.9%) acetabular liners have been replaced for excessive polyethylene wear, and an additional four (7.3%) show sufficient wear to produce obvious radiographic eccentricity of the femoral head. All of the revised liners had 32-mm femoral heads and an initial polyethylene thickness of less than 6 mm. Although the results reflect excellent fixation of this component in the medium term, the incidence of exchange of the polyethylene liner for excessive wear is unacceptably high. The reduction in polyethylene thickness associated with the use of a metal-backed component and a 32-mm articulation was one of the factors contributing to the accelerated wear patterns seen in this series.