Definition and validation of a system for classifying the undersized Corail femoral stem in total hip arthroplasty

Abstract

Introduction:

The uncemented total hip arthroplasty relies on a secure initial fixation of the femoral stem to achieve osseointegration. Undersizing of the femoral implant compromises this. Surgeons routinely review postoperative radiographs to assess appropriate sizing, but existing methods of assessment lack standardisation. We present a system of accurately and reliably classifying radiological undersizing, which will help us better understand the factors that might have led to undersizing.

Aim:

To describe and evaluate a classification system for assessing radiological undersizing of the uncemented stem in hip arthroplasty.

Method:

We conducted a retrospective review of 1,337 consecutive hip arthroplasties using the Corail stem. Two independent investigators reviewed post-operative radiographs and classified them as either appropriately sized or undersized. Undersized stems were sub-categorised into four subtypes: uniformly undersized, varus undersized, valgus undersized or ‘cocktail-glass’ undersized. Inter- and intra-observer agreement was determined. The accuracy of our classification system was validated by comparison with digital re-templating. We further assessed patient demographics and stem size in relation to sizing.

Results:

1 in 5 cases (19.75%) were deemed radiologically undersized. The commonest subtypes of undersizing were uniformly (47%) and varus (39%) undersized. When assessing sizing and subtype categorisation, inter-observer agreement was 89–92% and intra-observer agreement 86%. Classification decisions showed 92% and 97% accuracy for uniformly undersizing and varus undersizing respectively when validated against digital re-templating. Age, gender and smaller stem size were significantly associated with radiological undersizing. The Corail KLA model (125° neck) was found to have a higher incidence of stems undersized in varus.

Conclusions:

This study describes and validates a classification system for the analysis of radiological undersizing.

Keywords

Hydroxyapatite uncemented undersizing

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References

National Joint Registry for England, Wales and Northern Ireland. NJR 16th annual report, http://www.njrcentre.org.uk/njrcentre/NewsandEvents/NJR14thAnnualReportrecordnumberofproceduresduring201617/tabid/1453/Default.aspx (2019, accessed 29 September 2019).

Chambers

St Clair

Froimson

MI.

Hydroxyapatite-coated tapered cementless femoral components in total hip arthroplasty. J Arthroplasty 2007; 22: 71–74.

Reikerås

Total hip arthroplasty with a fully hydroxyapatite-coated stem: a cohort study during 23–28 years. J Arthroplasty 2017; 32: 1543–1546.

Jacquot

Bonnin

Machenaud

, et al. Clinical and radiographic outcomes at 25–30 years of a hip stem fully coated with hydroxylapatite. J Arthroplasty 2018; 33: 482–490.

Engh

O’Connor

Jasty

, et al. Quantification of implant micromotion, strain shielding, and bone resorption with porous-coated anatomic medullary locking femoral prostheses. Clin Orthop Relat Res 1992; 285: 13–29.

Jasty

Bragdon

Burke

, et al. In vivo skeletal responses to porous-surfaced implants subjected to small induced motions. J Bone Joint Surg Am 1997; 79: 707–714.

Søballe

Hansen

Brockstedt-Rasmussen

, et al. Hydroxyapatite coating converts fibrous tissue to bone around loaded implants. J Bone Joint Surg Br 1993; 75: 270–278.

Magill

Hill

O’Brien

, et al. Observed effect of femoral component undersizing and a collarless design in the development of radiolucent lines in cementless total hip arthroplasty. Arthroplast Today 2020; 6: 99–103.

Magill

Blaney

Hill

, et al. Impact of a learning curve on the survivorship of 4802 cementless total hip arthroplasties. Bone Joint J 2016; 98–B: 1589–1596.

10.

Jameson

Baker

Mason

, et al. Independent predictors of failure up to 7.5 years after 35 386 single-brand cementless total hip replacements. Bone Joint J 2013; 95–B: 747–757.

11.

Hoskins

Bingham

Lorimer

, et al. The effect of size for a hydroxyapatite-coated cementless implant on component revision in total hip arthroplasty: an analysis of 41,265 stems. J Arthroplasty 2020; 35: 1074–1078.

12.

Rivera

Leonardi

Evangelista

, et al. Risk of stem undersizing with direct anterior approach for total hip arthroplasty. Hip Int 2016; 26: 249–253.

13.

Aldinger

Jung

Breusch

, et al. Survival of the cementless Spotorno stem in the second decade. Clin Orthop Relat Res 2009; 467: 2297–2304.

14.

Fottner

Woiczinski

Kistler

, et al. Influence of undersized cementless hip stems on primary stability and strain distribution. Arch Orthop Trauma Surg 2017; 137: 1435–1441.

15.

Vidalain

Selmi

Beverland

, et al. (eds.). The CORAIL^® Hip System: a practical approach based on 25 years of experience. Berlin, Heidelberg: Springer-Verlag, 2011.

16.

Cohen

A coefficient of agreement for nominal scales. Educ Psychol Meas 1960; 20: 37–46.

17.

Jameson

Baker

Mason

, et al. Independent predictors of failure up to 7.5 years after 35 386 single-brand cementless total hip replacements: a retrospective cohort study using National Joint Registry data. Bone Joint J 2013; 95–B: 747–757.

18.

Piggott

Lyons

Murphy

, et al. Total hip replacement revision in a single brand small cementless stem – our experience after the findings of the National Joint Registry. Arch Bone Jt Surg 2018; 6: 501–507.

19.

Karayiannis

Cassidy

Hill

, et al. The relationship between canal diameter and the Dorr classification. J Arthroplasty 2020; 35: 3204–3207.

20.

Courtin

Viste

Subtil

, et al. Cementless lateralized stems in primary THA: mid-term survival and risk factors for failure in 172 stems. Orthop Traumatol Surg Res 2017; 103: 15–19.

21.

Cantin

Viste

Desmarchelier

, et al. Compared fixation and survival of 280 lateralised vs 527 standard cementless stems after two years (1–7). Orthop Traumatol Surg Res 2015; 101: 775–780.

22.

Ramaniraka

Rakotomanana

Rubin

, et al. [Noncemented total hip arthroplasty: influence of extramedullary parameters on initial implant stability and on bone-implant interface stresses]. Rev Chir Orthop Reparatrice Appar Mot 2000; 86: 590–597.