Screw fixation in stemless shoulder arthroplasty for the treatment of primary osteoarthritis leads to less osteolysis when compared to impaction fixation

Abstract

Background Stemless total shoulder arthroplasty is a well-established and reliable surgical treatment option for glenohumeral osteoarthritis resulting in loss of pain and improvement of shoulder function. Currently the two methods for the fixation of the humeral component are either screw fixation or impaction. The purpose of this study is the clinical and radiological comparison of two different stemless designs (screw fixation vs impaction) for total shoulder arthroplasties in patients suffering from primary glenohumeral osteoarthritis. Methods A retrospective cohort study including 39 patients with a mean age of 67 years and a minimum follow-up of 2 years was performed. Patients were separated into two groups based on the selected implant. In group A (n = 18) a screw fixation design and in group B (n = 21) an impaction type design was used. For clinical examination the Constant-Murley-Score (CS) and Subjective-Shoulder-Value (SSV) were evaluated. Radiological examination was performed on true-AP, axial and Y-view radiographs. Results In group A the CS increased from 27.1 to 65.2 points and SSV from 27.3 to 76.7% (p < 0.05). No osteolysis of the medial calcar or subsidence of the humeral implant were found in this group. In group B the CS increased from 29.0 to 72.6 points and SSV from 33.1 to 85% (p < 0.05). Osteolysis of the medial calcar was present in seven patients in this group. No signs for humeral loosening were found in both groups. Conclusion Impaction and screw fixation total shoulder arthroplasty for primary glenohumeral osteoarthritis using a stemless device provide reliable clinical results. The screw fixation seems to prevent osteolysis of the medial calcar.

Midterm results of stemless impaction shoulder arthroplasty for primary osteoarthritis: a prospective, multicenter study

“…A study by Alikhah et al has shown that stemless shoulder arthroplasty implants relying on either “press-fit” impaction or screw fixation techniques have been shown to share similar results in terms of clinical and radiographic outcomes. 2 Although medial calcar resorption was documented at a higher rate in patients with the impaction-fitted prosthesis, there were no significant differences in clinical function when compared with patients who were treated with a screw fixation designs. 2 The authors hypothesized that impaction-fitted implants are more prone to medial calcar resorption, whereas the screw fixation prosthesis permits a better load distribution due to its baseplate and constant rim load.…”

“… 2 Although medial calcar resorption was documented at a higher rate in patients with the impaction-fitted prosthesis, there were no significant differences in clinical function when compared with patients who were treated with a screw fixation designs. 2 The authors hypothesized that impaction-fitted implants are more prone to medial calcar resorption, whereas the screw fixation prosthesis permits a better load distribution due to its baseplate and constant rim load. Further theories suggest that particles from the breakdown of polyethylene may be responsible for the occurrence of “humeral notching” 33 when there is impingement of the medial calcar against the glenoid component.…”

Stress shielding following stemless anatomic total shoulder arthroplasty

“…Recently, Akilhah et al compared a hollow screw design to the impaction type design used in this study and demonstrated that the hollow screw with a trunnion may prevent and be protective of medical calcar bone resorption. 22 Proximal stress shielding may also occur when there is distal contact of the implant with the inner aspect of the lateral cortex. This leads to proximal bone adaptations as the loads are transmitted from the metallic humeral head, thru the stemless implant, and preferentially exit the implant distally at the contact location with the inner cortex.…”

“…Recently, Akilhah et al compared a hollow screw design to the impaction type design used in this study and demonstrated that the hollow screw with a trunnion may prevent and be protective of medical calcar bone resorption. 22 …”

Innovations in Shoulder Arthroplasty

“…Based on work by Habermeyer et al and Krukenberg et al, there does not appear to be a difference in terms of humeral loosening (n = 0 in both designs), humeral osteophytic exostosis (n = 0 in both designs), or functional outcomes [ 8 , 9 ]. Radiographic medial calcar resorption occurs more often with the impaction design, but there does not appear to be a clinical implication of this, as both designs result in significantly improved Constant and Subjective Shoulder Value (SSV) scores [ 8 , 10 ].…”