[Replacement of the anterior cruciate ligament by a PET prosthesis (Trevira extra-strength) as a salvage procedure in chronically unstable previously operated knee joints. Intermediate to long-term results of a clinical study]

[Artificial ligaments applied in anterior cruciate ligament repair and reconstruction: Current products and experience]

The application of artificial ligament products in anterior cruciate ligament (ACL) surgeries has gone through a long twisty way. In the 1970s, early artificial ligament products were initially used for ACL surgeries, which showed poor clinical efficacy and eventually ended up in failure. Over the last 20 years, there has been a growing number of ACL reconstruction with new artificial ligament products, including the Leeds-Keio TM, the LARS TM (Ligament Advanced Reinfocement System), and the Trevira Hochfest TM. Among these new products, the LARS TM has been more commonly applied for ACL surgeries. Although these new artificial ligament products have good mechanical properties and show significant improvement of cumulative failure and complication rate, they still have limitations.

Aseptic arthritis after ACL reconstruction by Tape Locking Screw (TLS®): report of two cases

In Tape Locking Screw (TLS(®)) ligamentoplasty, transplant bone fixation uses polyethylene terephthalate (PET). We report two cases of aseptic arthritis following anterior cruciate ligament (ACL) reconstruction using this material. Diagnosis was founded on negative sampling and complete cure following arthroscopic lavage and synovectomy without curative antibiotherapy. This complication was also described with other synthetic materials used in this indication (Dacron, PFTE, carbon), and with PET as transplant material but never as bone fixation material. The physiopathological hypothesis is in terms of PET particle release in the suprapatellar bursa; sinking the strips into the bone as fully as possible on implantation could avoid impingement. Longer TLS(®) ligamentoplasty series with adequate follow-up will be needed in order to estimate the true incidence of this complication.

Effects of revisional ACL surgery in semi-professional athletes in "high-risk pivoting sports" with chronic anterior instability of the knee

This is a retrospective study of semi-professional athletes in "high-risk pivoting sports" after repetitive injuries of the anterior cruciate ligament (ACL) with chronic anterior instability of the knee. Effects of revisional ACL surgery on the progression of osteoarthritis, sport capacity, and knee pain were observed. Twenty-four patients, with an average age of 25.5 years, were examined on average 36.9 months postoperatively. Compared with the preoperative findings we noted a significant increase in the Lysholm and the Tegner activity score (P < 0.001). Sixteen patients (67%) were able to continue their sporting career; 17 patients (71%) were completely satisfied with the operative result. Nevertheless, 15 patients (63%) complained of persistent pain caused by sport activity. According to the Fairbank scale, 15 patients (63%) showed an increase in osteoarthritic signs between the preoperative and follow-up roentgenograms. Furthermore, there was a highly significant correlation (P < 0.001) between progression of osteoarthritis and continuous sport activity. We conclude that, after stabilization with a "bone-tendon-bone" autograft, athletes have a good chance to return to their sport. In most patients, the knee pain persisted and progression of osteoarthritis was detected. In individuals who play sport continuously, we recommend an annual follow-up with clinical examination and roentgenographic or magnetic resonance imaging examinations.

Comparative evaluation of different anchoring techniques for synthetic cruciate ligaments. A biomechanical and animal investigation

Under certain well-defined indications alloplastic material may be used in cruciate ligament surgery. The stability and survival of such a synthetic ligament is to a great extent dependent on the anchorage with which it is fastened to the bone. Most fixation methods have proved to be too weak or have revealed other essential drawbacks, resulting in clinical and experimental failure. A new ligament fixation device (LFD) was developed and tested biomechanically and in animal experiments. In the biomechanic investigation the new LFD was compared to single staples, double staples in the belt-buckle technique, and ligament guidance through additional bone tunnels (Z-technique). The tests were carried out on human cadaver knees, plastic bones, and dog stifle joints. The evaluated parameters were linear and maximum load, stiffness, and elongation. In addition, hysteresis tests were performed to assay the long-term resistance of the fixation. The tests showed a significant superiority of the LFD in all measured variables compared to the other anchorages. The pull-out strength, at 1866 +/- 43 N (cadaver knee), was about four times that for the single staple, and about twice as high as that for the double staple and Z-technique. The animal experiments were performed on German shepherd cross-breed dogs. In six animals the anterior cruciate ligaments were excised bilaterally and replaced by a 6-mm Trevira ligament, on one side anchored with staples in the Z-technique, on the other with the LFD. Postoperatively the dogs were allowed to move freely; no additional protection was employed. After 6 months the animals were sacrificed and the knees examined macroscopically, radiologically, microscopically, and by biomechanical testing. After half a year of implantation, the pull-out strength of the alloplastic ligament was 662 +/- 62 N for the LFD and 531 +/- 67 N for the staples. Three ligaments in the staple group and one in the LFD group had ruptured completely, and two ligaments partially, one in each group. The average anterior drawer in the LFD group was 2.8 mm, in the staple group 4.0 mm. In all cases the alloplastic ligament was separated from the bone by a fibrous interface. None of the fixation devices showed signs of loosening. There was no foreign body reaction around the anchorages. Major cartilage degeneration was observed in two stifle joints of each group, mainly associated with instability.