Nils Reimers

Evidence Based Development of a Novel Lateral Fibula Plate (VariAx Fibula) Using a Real CT Bone Data Based Optimization Process During Device Development

Development of novel implants in orthopaedic trauma surgery is based on limited datasets of cadaver trials or artificial bone models. A method has been developed whereby implants can be constructed in an evidence based method founded on a large anatomic database consisting of more than 2.000 datasets of bones extracted from CT scans. The aim of this study was the development and clinical application of an anatomically pre-contoured plate for the treatment of distal fibular fractures based on the anatomical database. 48 Caucasian and Asian bone models (left and right) from the database were used for the preliminary optimization process and validation of the fibula plate. The implant was constructed to fit bilaterally in a lateral position of the fibula. Then a biomechanical comparison of the designed implant to the current gold standard in the treatment of distal fibular fractures (locking 1/3 tubular plate) was conducted. Finally, a clinical surveillance study to evaluate the grade of implant fit achieved was performed. The results showed that with a virtual anatomic database it was possible to design a fibula plate with an optimized fit for a large proportion of the population. Biomechanical testing showed the novel fibula plate to be superior to 1/3 tubular plates in 4-point bending tests. The clinical application showed a very high degree of primary implant fit. Only in a small minority of cases further intra-operative implant bending was necessary. Therefore, the goal to develop an implant for the treatment of distal fibular fractures based on the evidence of a large anatomical database could be attained. Biomechanical testing showed good results regarding the stability and the clinical application confirmed the high grade of anatomical fit.

Ultrasonically Assisted Anchoring of Biodegradable Implants for ChevronOsteotomies – Clinical Evaluation of a Novel Fixation Method

Reconstructive osteotomies for the treatment of Hallux valgus are among the most prevalent procedures in foot and ankle surgery. The combination of biodegradable materials with an innovative method for fixation by application of ultrasonic energy facilitates a new bonding method for fractures or osteotomies. As clinical experience is still limited, the aim of this study was to assess the safety and performance of the SonicPin system for fixation of Austin/Chevron osteotomies. Chevron osteotomy was performed on 30 patients for the treatment of Hallux valgus. The used SonicPins were made from polylactide and are selectively melted into the cancellous bone structure during insertion by ultrasonic energy. Patients were followed for one year, which included X-ray and MRI examinations as well as evaluation of life quality by EQ-5D (EuroQol). The MRI after three months showed adequate bone healing in all cases and no signs of foreign body reactions, which was again confirmed by MRI 12 months postoperatively. The bony healing after 12 months was uneventful without any signs of foreign body reactions. In summary, based on the low complication rate and the significant improvement in health related quality of life (EQ-5D) reported in this study, fixation of an Austin/Chevron osteotomy with a SonicPin for treatment of Hallux valgus can be considered to be safe and efficient over the short term. Level of Clinical Evidence: Therapeutic Level III.

Biomechanical evaluation of novel ultrasound-activated bioresorbable pins for the treatment of osteochondral fractures compared to established methods.

Abstract Background: Osteochondral injuries often lead to osteoarthritis of the affected joint. All established systems for refixation of osteochondral defects show certain disadvantages. To address the problem of reduced stability in resorbable implants, ultrasound-activated pins were developed. By ultrasound-activated melting of the tip of these implants, a more secure anchoring is assumed. Materials and methods: The aim of the study was to investigate if ultrasound-activated pins can provide secure fixation of osteochondral fragments compared to screws and conventional resorbable pins. In a biomechanical laboratory setting, osteochondral fragments of the medial femoral condyle of sheep were refixated with ultrasound-activated pins [US fused poly(L-lactide-co-D,L-lactide) (PLDLLA) pins], polydioxanone (PDA) pins and conventional titanium screws. Anchoring forces of the different fixation methods were examined, registered and compared concerning shear force and tensile force. Results: Concerning the pull out test, the US fused PLDLLA pins and titanium screws (~122 N and ~203 N) showed comparable good results, while the PDA pins showed significantly lower anchoring forces (~18 N). Examination of shear forces showed a significantly higher anchoring of the screws (~248 N) than the US fused PLDLLA pins (~218 N). Nevertheless, the US fused PLDLLA pins could significantly outperform the PDA pins (~68 N) concerning shear forces. Conclusion: The US fused PLDLLA pins demonstrated a comparable anchorage to the fixation with screws, but were free from the disadvantages of metal implants, i.e. the need for implant removal. The PDA pin application showed inferior biomechanical properties.