Abstract
BackgroundScaphoid fractures are the most common carpal fractures. They often need to be treated by surgery, where the use of a compression screw is the globally accepted gold standard. Surgeons may choose between different implant materials including titanium alloys, which remain in the body or are removed after healing. An alternative are biodegradable magnesium-based implants. Properties of magnesium alloys include high stability, osteoconductivity, potential reduction of infections and few artifacts in magnetic resonance imaging (MRI). The aim of this trial is to demonstrate non-inferiority of magnesium-based compression screws compared with titanium Herbert screws for scaphoid fractures.MethodsThe trial is designed as a multicenter, blinded observer, randomized controlled parallel two-group post market trial. Approximately 190 patients will be randomized (1:1) with stratification by center either to titanium or magnesium-based compression screws. Follow-up is 1 year per patient. Surgical procedures and aftercare will be performed according to the German treatment guideline for scaphoid fractures. The first primary endpoint is the patient-rated wrist evaluation (PRWE) score after 6 months. The second primary endpoint is a composite safety endpoint including bone union until 6 months, no adverse device effect (ADE) during surgery or wound healing and no serious ADE or reoperation within 1 year. The third primary endpoint is the difference in change MRI artifacts over time. Non-inferiority will be investigated for primary endpoints 1 (t-test confidence interval) and 2 (Wilson’s score interval) using both the full analysis set (FAS) and the per protocol population at the one-sided 2.5% test-level. Superiority of magnesium over titanium screws will be established using the FAS at the two-sided 5% test-level (Welch test) only if non-inferiority has been established for both primary endpoints. Secondary endpoints include quality of life.DiscussionThis study will inform care providers whether biodegradable magnesium-based implants are non-inferior to standard titanium Herbert screws for the treatment of scaphoid fractures in terms of wrist function and safety. Furthermore, superiority of magnesium-based implants may be demonstrated using MRI, which is used as surrogate endpoint for screw degradation.Trial registrationDRKS, DRKS00013368. Registered Dec 04, 2017.
Highlights
Scaphoid fractures are the most common carpal fractures
Superiority of magnesium-based implants may be demonstrated using magnetic resonance imaging (MRI), which is used as surrogate endpoint for screw degradation
Surgical treatment is generally recommended for unstable fractures, which include fractures with displacement ≥1 mm or ≥ 2 mm, comminuted fractures, perilunate fracture-dislocation and all fractures in the proximal third because of a long immobilization time and a high risk for pseudarthrosis [4]
Summary
Study design SCAMAG is a randomized, controlled, parallel-group, open-label with blinded observer, multicenter trial with two groups for comparing biodegradable magnesiumbased screws with standard titanium Herbert screws. This leads to the following assumptions for the sample size calculations for the first primary endpoint: Allocation ratio 1:1, type I error level 0.025 one-sided, power 0.9, expected difference between titanium and magnesium-based screws: Δ1 = 0, common standard deviation: σ = 20, non-inferiority margin: Δ0 = 10, drop-out 10%. If non-inferiority has been established for the first primary endpoint and the second primary endpoint, the power to establish superiority for the third primary endpoint, the change in artifacts endpoint is virtually 100% under the following assumptions: type I error level 0.025 one-sided, expected difference between titanium and magnesium-based screws: Δ1 = 3.0, common standard deviation: σ = 1.0, sample size per group: nA = nB = 10, dropout 10%, effective sample size per group: nA = nB = 9.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
