Radiologic evaluation of the healing of the greater tubercle after humeral hemiarthroplasty with Aequalis-fracture-implants for proximal humeral fracture: a retrospective cohort study in 45 shoulders.

Introduction: Development and use of specific anatomic prosthesis for shoulder's fracture aimed to reach the best rate of consolidation of the greater tubercle, which means a cuff restitution to improve functional results. The lack of bone healing of the tubercles suggested the use of a fenestrated humeral implant with interposition of a bone graft in the metaphyseal part of the prosthesis. This characteristic of specific implant, have few reports in the literature, leading us to the current retrospective study aiming: 1) to evaluate the healing rate of the greater tubercle after implantation of fracture dedicated anatomic implant, which includes a fenestration in the prosthetic metaphysis for the addition of a cortico cancellous graft, 2) to asses on patients with proximal humerus fractures, the bone healing of the greater tubercle close to the intraprosthetic bone graft.

Hypothesis: The specific "implant-fracture" can achieve a high rate of bone healing of the humeral greater tubercle.

Patients and methods: Between January 2001 and December 2020, fifty-one patients were operated on by implantation of fracture dedicated implant for proximal humerus fracture. Six were excluded (2 operated for revision, 2 operated after 3 weeks, 1 died, 1 without follow-up). In total 45 patients were included in radiological analysis, clinical analysis had been performed on 23/45 patients at the longest follow up, the other 22/45 were only analyzed on radiographies. Mean-aged 66 years (range, 47 years -88 years), 25/45 (56%) of women, with 3-4-parts fractures according to Neer's classification. The techniques of tubercle fixation were isolated cerclages of combined horizontal cerclages and vertical sutures. Position and healing of the greater tubercle was controlled through antero-posterior and lateral X-Rays views at the longest follow-up (mean 50 months, range 3-193 months). Peroperative techniques of fixation, clinical and functional outcomes were noted and correlated to the radiologic position of the greater tubercle and the graft evolution. Factors associated with healing and anatomic position had been investigated.

Results: The rate of greater tubercle healing was 32/45 (73%). Factors significantly associated with greater tuberosity consolidation were higher age (p = 0.04) and the addition of a vertical osteosuture to the horizontal suture of the greater tubercle (p = 0.01). The rate of anatomic position of the greater tubercle was 15/45 (33%) of cases. When the fixation of the tuberosity was made with vertical suture, good position of the tuberosity was observed in 68% (17/24) at the longest follow-up.

Discussion: Our results were in accordance with the literature, but the current study underlined there were two types of factors influencing tubercle healing in the literature: the technique of fixation of the tubercle and the patient's age.

Level of evidence: level IV cohort study without control group.