ZimmerBiomet – Big Head


Hip Replacement – Mid-term outcomes of highly cross-linked polyethylene hip replacement (BHLH study)


The hip joint is a ball and socket joint. Dislocation (when the new ball comes out of the socket) is a potential complication of hip replacement. This is a research study evaluating whether a larger femoral head (ball) reduces the risk of dislocation, and whether different head sizes cause the hip replacement to wear out at different rates.

You can read the original publication here:

Howie DW, Holubowycz OT, Middleton R, The Large Articulation Study Group. Large femoral heads decrease the incidence of dislocation after total hip arthroplasty. A randomized controlled trial. J Bone Joint Surg Am. 2012;94:1095-102.

JBJS (lww.com)

Study Description

The current study is a 7 to 10 year follow-up study of patients enrolled in the randomised controlled trial described in ACTRN12609000678291. In the RCT patients undergoing total hip replacement were randomised to receive either a large 36 mm articulation (intervention) or standard 28 mm articulation (control).


Primary outcome

% of patients with osteolytic lesions exceeding 1 cubic centimetre, as measured by CT.


7-10 years following primary total hip replacement

Secondary outcomes

Incidence of dislocation. Dislocation is measured initially through responses to a Hip Instability Questionnaire and Hospital Visit Questionnaire. Dislocations must then be confirmed radiologically.

Polyethylene wear, measured using PolyWare, a computer program which measures wear using plain radiographs.

Acetabular component migration, measured using EBRA (Ein Bild Roentgen Analyse), a computer program which measures migration using plain radiographs.

Incidence of re-operation or revision of index total hip replacement.

Other complications, such as infection, pain and loosening, as reported by patient.


7-10 years following total hip replacement