Original ArticleBioabsorbable magnesium versus standard titanium compression screws for fixation of distal metatarsal osteotomies – 3 year results of a randomized clinical trial☆
Section snippets
Background
For hallux valgus deformities, commonly distal metatarsal osteotomies (DMO) are performed. The chevron osteotomy was initially described for mild to moderate deformities by Corless and later Austin [1]. Generally good clinical results are achieved with this operation [2], [3]. Although initially internal fixation was not considered necessary, for better control of the osteotomy and to prevent tilting of the metatarsal head, fixation is nowadays generally recommended. Different fixation
Study design
Between March 2010 and July 2011, we recruited the patients for this randomized controlled study. Inclusion criteria were defined as symptomatic hallux valgus with indication for chevron osteotomy and no additional surgery, age between 40 and 79 years, secure contraceptive method in female patients and no other pathology of the lower extremity. Exclusion criteria were set as previous operations on the symptomatic foot, BMI >32, pregnancy, neurological pathologies, bone mineral density
Clinical results
There was no preoperative difference between the Mg and the Ti-group regarding AOFAS (p = 0.874) and pain-NRS (p = 0.295). The AOFAS (p = 0.002) and pain-NRS (p = 0.001) improved significantly from pre-to 3 years postoperatively. Postoperatively there were no significant differences for pain-NRS (p = 0.94), AOFAS (p = 0.285), FAAM-ADL (p = 0.756), FAAM-Sport (p = 0.606) and SF-36 (p = 0.38) between the Mg and the Ti-groups (Table 2).
All patients achieved the preoperative activity level. The
Discussion
In this mid-term follow-up study, we found comparable clinical results after fixation of distal metatarsal osteotomies using metallic bioabsorbable Mg-screws or standard Ti-screws. MRI after 3 years showed a sufficient bone healing and less artifacts in the Mg-group compared to the standard treatment group. In the position of the former implant a hypointense structure was found indicating a mineralized structure most probably similar to cortical bone.
Conclusion
In this study, distal metatarsal osteotomies fixed with either a magnesium or titanium implant show no significant difference in the clinical outcome after three years. Magnesium implants have advantages in imaging due to less artifacts. Magnesium based implants are degraded but are not fully remodeled after 3 years, yet.
Compliance with ethical standards
Conflict of Interest: The study was financially supported by Syntellix AG, Hannover, Germany. HW was member of the supervisory board of Syntellix AG, Hannover, Germany.
Ethical approval: The study was approved by the responsible ethical board and registered in the German clinical trial register.
Informed consent: Informed consent was obtained from all individual participants included in the study.
Acknowledgement
We thank Yvonne Noll for the organization of the follow up controls and data acquisition. We thank Christian Modrejewski for patient examination and data collection.
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The work was performed at the: Orthopedic Clinic in Diakovere Annastift, Hannover Medical School, Anna-von-Borries Strasse 1-7, 30625 Hannover, Germany.