Clinical Application of Mg Based Biodegradable Material for Fracture Fixation in the Adult Skeleton
Condition: Fracture of Medial Malleolus
MeSH terms: Fractures, Bone
Study type: Interventional
Phase: Phase 2/Phase 3

Summary: 
      This study is a prospective, non-randomized trial for the treatment of fractures of the
      medial malleolus using lean, bioabsorbable, rare-earth element (REE) free, magnesium
      (Mg)-based biodegradable screws in the adult skeleton.

      A total of 20 patients with isolated, bimalleolar, or trimalleolar ankle fractures were
      recruited between July 2018 and October 2019. Fracture reduction was achieved through
      bioabsorbable Mg-based screws composed of pure Mg alloyed with zinc (Zn) and calcium (Ca)
      (0.45 wt% Zn and 0.45 wt% Ca; ZX00). Visual analogue scale (VAS) and the presence of
      complications (adverse events) during follow-up (12 weeks) were used to evaluate the clinical
      outcomes. The functional outcomes were analyzed through the range of motion (ROM) of the
      ankle joint and the American Orthopaedic Foot and Ankle Society (AOFAS) score. Fracture
      reduction and gas formation were assessed using several plane radiographs.
    

Detailed description: 
      The pilot study was designed as a prospective, nonrandomized trial for the treatment of
      displaced fractures of the medial malleolus with a lean, REE-free, Mg-based biodegradable
      implant in the adult skeleton. The trial was conducted according to the Good Clinical
      Practice (ISO 14155:2011) standard and the Declaration of Helsinki.The study was performed at
      the Department of Orthopaedics and Trauma at the Medical University of Graz and approved by
      the ethics committee (28 - 071 ex 15/16). A total of 20 subjects were recruited and operated
      on by three experienced surgeons in the centre between July 2018 and October 2019. Inclusion
      focused on adults aged between 18 and 65 years presenting with a displaced isolated medial
      malleolus fracture, a bimalleolar ankle fracture, or a trimalleolar ankle fracture. Fracture
      displacement was defined as diastasis of the fracture in any direction of 2 mm or more.
      Exclusion criteria were pathological fractures, underlying diseases (particularly bone
      diseases, kidney diseases, diabetes mellitus), polytraumatized patients, and pregnant or
      breastfeeding women.Written informed consent was obtained from each patient before the
      surgery. All radiological data were stored in a picture archiving and communication system
      (PACS). Fractures were classified according to the Herscovici system.25

      Description of the bioresorbable device used: Ultra-high pure Mg (99.999%) was alloyed with
      Zn and Ca (0.45 wt% Zn and 0.45 wt% Ca) at 750°C under a protective gas atmosphere. Prepared
      screws had a length of 40 mm and a diameter of 3.5 mm. Implants were threaded at the distal
      part for use as traction screws.

      Surgery: All patients were operated in a supine position. In case of a bimalleolar or
      trimalleolar fracture, the fibular and the dorsal tibial fragments were treated before the
      medial malleolus. Subsequently, two parallel Kirschner wires perpendicular to the medial
      malleolar fracture line were positioned with fluoroscopic control. A cannulated drill bit
      with 2.7 mm width was used for preparing the hole. Subsequently, one wire was removed and the
      ZX00 compression screw was inserted into the hole. Final fixation of the fracture was
      achieved with the second bioabsorbable Mg screw after removal of the second wire. The
      insertion torque of the screws was limited at a force of 1.5 newton metre with a torque
      handle. In all patients, no additional implants other than the Mg screws were used for the
      fixation of the medial malleolus. Patients with bimalleolar fractures and trimalleolar
      fractures were fixed with titanium plates and screws. Moreover, patients were immobilized
      with an under-knee plaster cast four to six weeks postoperatively and encouraged to attempt
      full weight-bearing as tolerated. Ankle movement exercises were started immediately after
      removal of the plaster.

      Assessments and measurements: For each subject, the study consisted of assessments conducted
      preoperatively, immediately after operation and postoperative followup visits. During
      follow-up, complications including vital signs, erythema, swelling, pain, secretions, wound
      healing disorders, wound infections, or implant infections were recorded. Pain was assessed
      using visual analogue scale (VAS). Blood analysis and detection of Ca and Mg were recorded.
      Functional outcomes were evaluated through range of motion (ROM) in dorsal and plantar
      flexion. Additionally, the American Orthopaedic Foot and Ankle Society (AOFAS) score was
      performed after three months. Anteroposterior and lateral ankle radiographs (X-rays) were
      used to evaluate the fracture union and loss of reduction during follow-up. Postoperative
      radiograph evaluation was performed by two independent radiologists.

      The study was registered retrospectively on Clinicaltrials.gov.
    

Intervention name(s): BRI.MAG 2
Intervention type(s): Device
Intervention description(s): Patients presenting with dislocated isolated or combined fracture of the medialis malleolus, will be screened for eligibility. Every effort will be made to ensure eligibility of the patients prior to enrollment. 20 patients will be recruited for the study.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment