Risk factors for significant radiolucent line development in a fully coated hydroxyapatite stem

Abstract: Background

The risk factors for and clinical impact of radiolucent lines (RLL’s) in cementless total hip arthroplasty remain contentious. The aim of this work was to describe a method of classification that has clinical significance and to identify risk factors.

Methods

A cohort of 288 subjects with unrevised Corail® stems (DePuy Synthes, Warsaw, IN) were reviewed with radiographs and Oxford hip scores (OHS) at 10 years. Based on clinical experience three groups were defined; those with no RLL’s (NoRLL’s), those considered to have benign RLL’s (BenRLL’s) and those considered to have significant RLL’s (SigRLL’s). SigRLL’s were then compared to BenRLL’s and NoRLL’s to determine the validity of this classification.

Results

109 (37.8%) had NoRLL’s, 111 (38.5%) had BenRLL’s and 68 (23.6%) had SigRLL’s. No significant difference apart from gender was noted between the occurrence of BenRLL’s and NoRLL’s following multinomial regression analysis, consequently the NoRLL’s and BenRLL’s groups were combined (NoSigRLL’s) and compared to SigRLL’s. Non-crosslinked polyethylene (NXLPE) (odds ratio 4.6, p<0.001), collarless stem design (odds ratio 9.4, p<0.001), undersizing (odds ratio = 1.2 p=0.028) and male sex (odds ratio = 2.1, p=0.008) were risk factors for SigRLL’s. Regression analysis also revealed that increasing age at operation decreased the likelihood of SigRLL’s (p<0.001). Patients with SigRLL’s had significantly higher pain scores (p=0.005) although overall OHSs were not significantly different (p=0.364).

Conclusion

The definition of SigRLL’s proposed in this study was significantly associated with NXLPE, absence of a collar, undersizing and higher pain scores.

Article InfoPublication History

Accepted: July 1, 2021

Received in revised form: June 28, 2021

Received: March 15, 2021

Publication stageIn Press Journal Pre-ProofFootnotes

Location of study: Primary Joint Unit, Musgrave Park Hospital, Stockman’s Lane, Belfast, BT9 7JB, Northern Ireland

Mr Paul Karayiannis: Data collection, analysis, wrote manuscript

Dr Roslyn Cassidy: Data collection and analysis, manuscript editing

Prof Graham Isaac: Concept, manuscript editing

Ioan Hughes: Data collection, manuscript editing.