Aims

In metal-on-metal (MoM) hip arthroplasties and resurfacings, mechanically induced corrosion can lead to elevated serum metal ions, a local inflammatory response, and formation of pseudotumours, ultimately requiring revision. The size and diametral clearance of anatomical (ADM) and modular (MDM) dual-mobility polyethylene bearings match those of Birmingham hip MoM components. If the acetabular component is satisfactorily positioned, well integrated into the bone, and has no surface damage, this presents the opportunity for revision with exchange of the metal head for ADM/MDM polyethylene bearings without removal of the acetabular component.

Aims

The aim of this modified Delphi process was to create a structured Revision Hip Complexity Classification (RHCC) which can be used as a tool to help direct multidisciplinary team (MDT) discussions of complex cases in local or regional revision networks.

Aims

The aim of this study was to assess medium-term improvements following total hip arthroplasty (THA), and to evaluate what effect different preoperative Oxford Hip Score (OHS) thresholds for treatment may have on patients’ access to THA and outcomes.

The review of the first 325 Exeter Universal hips reported good long term survivorship despite the majority of cups being metal backed. We have reviewed the long term performance of the concentric all-polyethylene Exeter cups used with the Universal Exeter stem.

Clinical and radiographic outcomes of 263 consecutive primary hip arthroplasties in 242 patients with mean age 66 years (range, 18 to 89) were reviewed. 118 cases subsequently died none of whom underwent a revision. Eighteen hips have been revised; thirteen for aseptic cup loosening, three for recurrent dislocation and two for deep infection. Three patients (four hips) were lost to follow-up. The minimum follow-up of the remaining 123 hips was 10 years (mean 13.3 years, range 10–17). Radiographs demonstrated 6 (6%) of the remaining acetabular prostheses were loose. The Kaplan Meier survivorship at 14.5 years with endpoint revision for all causes is 91.5% (95% CI 86.6 to 96.2%). With endpoint revision for aseptic cup loosening, survivorship is 93.3% (CI 88.8 to 97.8%).

This series included a number of complex cases requiring bone blocks and/or chip autograft for acetabular deficiencies. The concentric all polythene Exeter cup and Exeter stem has excellent long term results particularly when factoring in the complexity of cases in this series.

Purpose: There is evidence that recommends the retention of a well-fixed cement mantle at the time of revision hip arthroplasty. The cement-cement interface has been proven to have a greater shear strength than a new bone-cement interface after removing the old cement mantle.

Method: This study reviewed a series of acetabular revision procedures with a minimum 2-year follow-up where the original cement mantle was left intact. From 1988 to 2004, 63 consecutive cement-in-cement revisions of the acetabular component were performed at our institution. Outcome was based on functional assessment using the Oxford, Charnley, and Harris scoring systems as well as radiographic analysis using the DeLee and Charnley criteria.

Results: In total 63 procedures were performed in 61 patients (40 female and 21 male), whose mean age at surgery was 74 years (range 40 to 99 years). 47 hips (75%) were performed for recurrent dislocation, 13 for aseptic loosening, 1 for pain, 1 for excessive shortening, and 1 for disarticulation of a constrained liner. No case was lost to follow-up. There was a significant improvement in the functional scores from the pre-operative status with the patients maintaining a low level of pain. There was one re-revision for aseptic cup loosening at 7 years, with 1 further case of radiological loosening identified at the latest review. There were 6 further cases of dislocation 5 of which were treated with further in-cement revisions. All other cases showed well-fixed components on radiographic analysis and no evidence of failure at the most recent follow up.

Conclusion: The cement-in-cement revision technique can be used in selected cases of acetabular revision surgery, providing satisfactory functional outcomes backed up by good radiographic results. Blood loss and surgical time are also significantly decreased.

Introduction: Recurrent dislocation can be a significant problem after total hip replacement. The use of a constrained tripolar liner is an option in the surgical treatment of dislocation or instability.

Methods: A retrospective review was carried out of patients identified from a prospective database. All patients had a constrained liner cemented onto a satisfactory pre-existing cement mantle, cemented into a reconstruction ring, or cemented into a well fixed cementless shell. The Osteonics Tripolar Liner was used in all cases; the outer aspect of the liner was prepared with a burr to create grooves and thus improve cement interlock. Data collected included demographics, reason for revision, re-revision rate, outcome and survival.

Results: There were 58 cases identified where a cemented constrained liner was inserted at revision hip surgery. Average age at time of surgery was 77years (range 40–94). There were 9 patients who died with less than 2 years follow-up; they were excluded, leaving a study group of 49 cases. No cases were lost to follow-up. Average duration of follow-up was 46months (range 24–76). There have been 4 infections, one of which required removal of prostheses and a 2-stage revision. There was one case of fall post-operatively and fracture of the contra-lateral femoral neck. There have been 4 implant failures requiring re-revision. All failures were due to disarticulation of the liner, 2 of which occurred in the same patient on separate occasions. There have been no revisions for loosening, and there have been no cases of failure at the bone-cement interface or at the cement-cement interface with the cement-in-cement technique. Overall survival of the cemented constrained liner was 90% at average 3.8years.

Conclusion: This study demonstrates that cementing a constrained liner into the acetabulum is a viable option in revision hip surgery, particularly in the management of instability.

Controversy exists with regard to the thickness of cement mantles that are necessary around the femoral components of cemented total hip arthroplasties. Conventional teaching, based on bench-top or computor models and theoretical analyses, as well as post-mortem & follow-up studies, suggests that the cement mantle should be complete and not less than 2–3mm in thickness. Mantles that are less than this are held to be at risk from mechanical failure in the long term; if they are incomplete, focal lysis may occur and progress to aseptic loosening.

However, long term experience with a number of French cemented femoral components suggests that these conventions may be erroneous. These French femoral components include the Charnley-Kerboull (stainless steel) and the Ceraver Osteal (Ti6Al4V) stems, in both of which the underlying design principle is that the stem should completely fill the femoral canal, the cement then being used purely to fill the gaps. Such a design philosophy implies that the cement mantles will be very thin, and since both of these stems are straight and the femoral medullary canal is not, the mantles may not only be thin, but also in places incomplete.

Conventional teaching would suggest that any stem utilising mantles of this type would fail from a combination of focal lysis and cement fracture. Yet the long term results of both of these stems have been outstandingly good, with extremely low levels of aseptic loosening and endosteal lysis, irrespective of the bearing combinations being used. Both these stems have a surface finish of Ra < 0.1 microns. A third French design, the Fare stem, manufactured from Ti6Al4V and based on the same principles, was associated with bad results when manufactured with a rough (> 1.5 microns) surface, and appreciably better results after the surface roughness was changed to < 0.1 microns.

These findings, that constitute the ‘French Paradox’, have profound implications for the mechanical behaviour of cement in the femur and for the mechanisms that underlie stem failure from loosening.