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Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_20 | Pages 55 - 55
1 Nov 2016
Almaawi A Deny A Roy A Massé V Lavigne M Vendittoli P
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Large bearing surfaces are appealing in total hip arthroplasty (THA) as they may help create a greater range of impingement free motion and reduce the risk of dislocation. However, attempts to achieve this with a metal bearing surface have been blighted by adverse reactions to metal debris. Ceramic bearings have a good long-term track record in more conventional head sizes, and manufacturing techniques now permit the use of larger ceramic bearing surfaces using monoblock uncemented acetabular components. In this study, we are reviewing the early results of the Maxera® acetabular component (Zimmer, Indiana) at our institution.

All data was collected prospectively. Maxera® acetabular component is a Titanium (Ti) shell with plasma sprayed Ti for the osteointegrative surface. Delta ceramic liner is inserted & locked into the cup shell by the manufacturer (non-modular). With the Maxera cup system, the bearing diameter is dictated by the acetabular component size. Acetabular components (AC) of 46 and 48 mm have a bearing diameter (BD) of 36 mm, AC of 50 and 52 mm: have a 40 mm BD, AC of 54 and 56 mm: have a BD of 44 mm and AC of 58–64: have a 48mm BD. Delta ceramic femoral head size of 44 and 48 mm have a modular Ti sleeve between the head and femoral stem trunnion. Femoral head sizes of 36 and 40 mm have no Ti sleeve. All THA had an uncemented femoral stem. Implants were inserted with a posterior approach. Patients were reviewed at 6 weeks, 6 months and then annually with radiographs. Clinical function was evaluated using WOMAC and UCLA scores along with joint perception questionnaires.

Five hundred components have been implanted in 442 patients (250 women, 192 men) with a mean age of 55, (min 17, max 80) and a mean BMI of 26.9 (min 17.8, max 51). The mean acetabular size was 54 (min 46, max 64), leading to a mean femoral head size of 44. At a minimum of two years follow-up (mean 3.8 years): 5 patients have been revised, 4 secondary to undetected intraoperative fracture of the femur and only one due to early displacement of a Maxera® cup (0.2%). Five patients reported a mild squeaking; two reported clicking and one patient presented with a symptomatic heterotopic ossification. The WOMAC score improved significantly post-operatively, (57.4 compared to 4.4 post-operatively, p<0.001). The mean post-operative UCLA score was 6.9. Sixty percent (60.6%) of patients rated their joint perception as either “natural” or “artificial without limitation”. two patients (0.4%) suffered a dislocation after high velocity trauma without recurrence after closed reduction. No ceramic component fracture was recorded.

This prospective study shows that this monoblock acetabular component provides an easy implantation with minimal complications. The ceramic bearing surface provides good clinical function and joint perception. Bearing surfaces of this design may provide an alternative to large head metal on metal (MoM) implants without the side effects of metal debris/ions.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_I | Pages 113 - 114
1 Mar 2009
Lavigne M Massé V Vendittoli P Roy A
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PURPOSE: The purpose of this study was to compare the level of post operative sport activity in a randomized study of SRA and THA.

INTRODUCTION: Return to high activity level has been proposed has an advantage of hip resurfacing (SRA) compared to THA. However, patient selection for SRA favours higher demand individuals, thus leading to a biased comparison of both techniques.

MATERIALS AND METHODS: Patients were randomized to THA or SRA. At minimum one year follow-up, the patients were asked about the activities they have resumed, the level of satisfaction regarding return to sports and the factors limiting full return to intense activities. 80 THA and 85 SRA with a mean follow-up of 16 months were analyzed.

RESULTS: The postoperative UCLA activity score was significantly higher in the SRA group (6.3 versus 7.1, p< 0.05). 77% of the SRA patients returned to high or moderate activity level vs 39% in the THA group (p=0.007). In the THA group, the activity level was mostly restricted due to concern about instability. However, some THA patients were still able to perform high demand activities.

DISCUSSION AND CONCLUSION: This study suggests that SRA allows return to higher activity level when compared to THA. This may be due in part to the larger diameter head of SRA which improves stability and suction-fit (reducing micro separation of the bearing during activities). Enhanced proprioception due to the retained femoral neck may also be involved in the bias towards SRA. Further follow-up is will determine if higher activity level is detrimental to implant survivorship