Cyst formation and bony ingrowth inside coil-type open-architecture anchors used for arthroscopic remplissage: a volumetric computed tomographic study of 50 anchors

Abstract

Background: The use of anchors in the proximal humerus during arthroscopic surgery can cause localized bone loss due to osteolysis and cyst formation. The purpose of this study was to use computed tomography (CT) to evaluate the incidence of implant-related bone loss and cyst formation after implantation of polyetheretherketone (PEEK) coil-type open-architecture anchors during remplissage for the management of Hill-Sachs defects (HSDs) in patients with shoulder instability.

Methods: This was a single-cohort, observational study with a minimum of 12 months of follow-up. Subjects undergoing arthroscopic instability surgery with HSD requiring remplissage were included. The volume of the bone defects and the degree of bony ingrowth into the anchor were measured on CT images.

Results: Thirty-one participants (28 males, 3 females; mean age 29.4 years, standard deviation [SD] 10.6) in whom 50 anchors (4.5-mm Healicoil PEEK double-loaded anchors) were used were evaluated with a CT performed at a mean of 14.1 (SD 3.74) months after surgery. Full bony ingrowth inside the anchor was found in 15 anchors (30%, range 17.8%-44.5%); clear ossification with a thin lucent rim was found in 10 anchors (20%, range 10.0%-33.7%); discontinuous ossification was found in 8 anchors (16%, range 7.2%-29.1%); and no ossification was observed inside 17 anchors (34%, range 21.2%-48.7%). Regarding bone defect size, no bone defect was identified in 15 anchors (30%, 95% CI 17.9%-44.6%), a partial bone defect was found in 17 anchors (34%, 95% CI 21.2%-48.7%), hole enlargement was found in 17 anchors (34%, 95% CI 21.2%-48.7%), and 1 anchor caused a cyst larger than twice the size of the hole made for anchor insertion (2%, 95% CI 0.1%-8.6%). At the 1-year evaluation, none of the participants presented recurrence or residual apprehension.

Conclusion: The use of PEEK coil-type open-architecture anchors for remplissage during instability surgery caused large cystic lesions in less than 10% of anchors. There was full bony ingrowth in one-third of anchors, and partial cancellous bone ingrowth occurred in another third of anchors.

Keywords: Hill-Sachs defect; Shoulder arthroscopy; bony ingrowth; coil-type open-architecture anchors; humeral cyst; osteolysis; remplissage; shoulder instability.