Suspensory fixation of grafts in anterior cruciate ligament reconstruction: a biomechanical comparison of 3 implants.

PURPOSE: Our purpose was to evaluate the biomechanical difference between 2 new soft-tissue anterior cruciate ligament (ACL) fixation devices (RetroButton [Arthrex, Naples, FL] and ToggleLoc [Biomet, Warsaw, IN]) and a clinically established implant (EndoButton CL; Smith & Nephew, Andover, MA). METHODS: In test session 1 biomechanical testing was performed by use of 48 porcine femora fixed to a material testing machine. In session 2 the implants were tested alone. Cyclic loading was carried out for 1,000 cycles, followed by a load-to-failure test. The tested devices were as follows: EndoButton CL, 20-mm and 40-mm loops; RetroButton, 12/20-mm and 12/40-mm loops; and ToggleLoc, 20-mm and 40-mm loops. RESULTS: In test session 1 the EndoButton CL showed higher motion per cycle (0.30 +/- 0.09 mm for 20-mm loop and 0.43 +/- 0.03 mm for 40-mm loop) but lower plastic displacement values (0.66 +/- 0.19 mm for 20-mm loop and 0.50 +/- 0.13 mm for 40-mm loop) than the objects of comparison. The RetroButton devices were the stiffest (331.47 +/- 133.92 N/mm for 12/20-mm loop and 265.66 +/- 103.97 N/mm for 12/40-mm loop). The highest ultimate failure load, however, was shown by the EndoButton CL devices. In test session 2 the EndoButton CL oscillated the most. The ToggleLoc devices elongated more than the objects of comparison (0.66 +/- 0.12 mm for 20-mm loop and 0.76 +/- 0.06 mm for 40-mm loop). The RetroButton devices were both the stiffest among the respective implants (542.7 +/- 148.0 N/mm for 12/20-mm loop and 379.0 +/- 40.1 N/mm for 12/40-mm loop). The EndoButton CL showed the highest values for displacement to failure (3.6 +/- 0.4 mm for 20-mm loop and 6.4 +/- 0.4 mm for 40-mm loop). The ToggleLoc devices failed the latest on load-to-failure testing. CONCLUSIONS: All tested implants could provide adequate fixation strength. Despite advantages in the design of the EndoButton CL regarding its handling, the 2 newly released products showed superior material properties. CLINICAL RELEVANCE: Suspensory fixation of hamstring grafts in ACL reconstruction is frequently associated with bone tunnel enlargement. Material properties and implant design may limit graft-tunnel motion and result in enlargement of the femoral bone tunnel. With improved implant design, suspensory graft fixation may still be an attractive fixation technique in primary and revision ACL reconstruction.

Shock wave therapy reduces necrotic flap zones and induces VEGF expression in animal epigastric skin flap model.

The effect of extracorporeal shock wave (ESW) therapy on skin flap survival and growth factor expression was investigated in a rat model using epigastric skin flap. Treatment and control groups each contained 20 animals. ESW effectively enhanced epigastric skin flap survival by significant reduction of areas of necrotic zones. At day 7 after the operation, necrotic zones of 4.2% were found in the ESW-treated group compared with 18.3% in the control group ( P < 0.01). Concomitantly, in tissue samples adjacent to the necrosis areas, increased vascular endothelial growth factor expression was observed in the ESW-treated animals (median 84.5%, range 57.4 to 94.5%) compared with the control group (median 46.7%, range 29.1 to 93.1%; P < 0.1). However, for expression of basic fibroblast growth factor, no difference was found between the two groups. The authors conclude that the success of the shock wave treatment may partly be due to modulation of growth factor expression.

Comparison of the effectiveness of gene therapy with transforming growth factor-beta or extracorporal shock wave therapy to reduce ischemic necrosis in an epigastric skin flap model in rats.

The induction of neoangiogenesis by exogenous growth factors in failing skin flaps has recently yielded promising results. Gene transfer with virus vectors has been introduced as a highly capable route of administration for growth factors, such as vascular endothelial growth factor or fibroblast growth factor. Extracorporal shock waves (ESW) deliver energy by means of high amplitudes of sound to the target tissue and have been shown to induce angiogenesis. We compared the effectiveness of gene therapy with adenovirus-mediated transforming growth factor-beta (TGF-beta) and ESW therapy to treat ischemically challenged epigastric skin flaps in a rat model. Thirty male Sprague-Dawley rats were divided into three groups of 10 each with an 8 x 8 cm epigastric skin flap. Rats received either subdermal injections of adenovirus (Ad) encoding TGF-beta (10(8) pfu) or ESW treatment with 750 impulses at 0.15 mJ/mm2. The third group received no treatment and served as a control group. Flap viability was evaluated after 7 days and digital images of the epigastric flaps were taken and areas of necrotic zones relative to total flap surface area calculated. Histologic evaluation and increased angiogenesis were confirmed by CD31 immunohistochemistry. Overall, there was a significant increase in mean percent surviving area in the Ad-TGF-beta group and the ESW group compared to the control group (ESW group: 97.7 +/- 1.8% vs. Ad-TGF-beta: 90.3 +/- 4.0% and control group: 82.6 +/- 4.3%; p < 0.05). Furthermore, in the ESW group mean percent surviving areas were significantly larger than in the Ad-TGF-beta group (ESW group: 97.7 +/- 1.8% vs. Ad-TGF-beta: 90.3 +/- 4.0%; p < 0.05). Flap vascularization was increased by Ad-TGF-beta and ESW with numerous vessels, however, there was no significant difference between the two treatment groups. We conclude that treatment with ESW enhances epigastric skin flap survival significantly more than Ad-TGF-beta treatment and thus represents a modality that is feasible, cost-effective, and less invasive compared to gene therapy with growth factors to improve blood supply to ischemic tissue.

Sciatic nerve enlargement in the Klippel-Trenaunay-Weber syndrome.

The case of a 35-year-old woman with Klippel-Trenaunay-Weber syndrome (KTWS) showing clinical symptoms of a peroneal nerve lesion is presented. An immense nerve enlargement along most of the sciatic, peroneal and tibial nerve was found to be due to a lipoma arising from the epi- and perineurium. Treatment consisted of extensive microsurgical neurolysis and excision of the tumor resulting in decompression of the affected nerves. Although rare, a perineural lipoma should be kept in mind in patients with KTWS showing neurological abnormalities.