Preliminary report of clinical experience with metal-on-highly-crosslinked-polyethylene hip resurfacing

Abstract

Objectives: Modern metal-on-metal (MoM) hip resurfacing arthroplasty (HRA), while achieving good results with well-orientated, well-designed components in ideal patients, is contraindicated in women, men with head size under 50 mm, or metal hypersensitivity. These patients currently have no access to the benefits of HRA. Highly crosslinked polyethylene (XLPE) has demonstrated clinical success in total hip arthroplasty (THA) and, when used in HRA, potentially reduces metal ion-related sequelae. We report the early performance of HRA using a direct-to-bone cementless mono-bloc XLPE component coupled with a cobalt-chrome femoral head, in the patient group for whom HRA is currently contraindicated.

Methods: This is a cross-sectional, observational assessment of 88 consecutive metal-on-XLPE HRAs performed in 84 patients between 2015 and 2018 in three centres (three surgeons, including the designer surgeon). Mean follow-up is 1.6 years (0.7 to 3.9). Mean age at operation was 56 years (sd 11; 21 to 82), and 73% of implantations were in female patients. All patients were individually counselled, and a detailed informed consent was obtained prior to operation. Primary resurfacing was carried out in 85 hips, and three cases involved revision of previous MoM HRA. Clinical, radiological, and Oxford Hip Score (OHS) assessments were studied, along with implant survival.

Results: There was no loss to follow-up and no actual or impending revision or reoperation. Median OHS increased from 24 (interquartile range (IQR) 20 to 28) preoperatively to 48 (IQR 46 to 48) at the latest follow-up (48 being the best possible score). Radiographs showed one patient had a head-neck junction lucency. No other radiolucency, osteolysis, component migration, or femoral neck thinning was noted.

Conclusion: The results in this small consecutive cohort suggest that metal-on-monobloc-XLPE HRA is successful in the short term and merits further investigation as a conservative alternative to the current accepted standard of stemmed THA. However, we would stress that survival data with longer-term follow-up are needed prior to widespread adoption.Cite this article: R. B. C. Treacy, J. P. Holland, J. Daniel, H. Ziaee, D. J. W. McMinn. Preliminary report of clinical experience with metal-on-highly-crosslinked-polyethylene hip resurfacing. Bone Joint Res 2019;8:443-450. DOI: 10.1302/2046-3758.810.BJR-2019-0060.R1.

Keywords: Arthroplasty; Hip arthritis; Hip resurfacing; Implant survival; Young patients.

Fig. 1

The custom metal-on-crosslinked-polyethylene (MoXLPE) hip resurfacing device. Component sizes used in this cohort ranged from 48 mm to 60 mm outer diameter (OD). Implants were individually prescribed and manufactured for each patient, based on templating with calibrated plain radiographs. Thicker components (4 mm to 5 mm minimum thickness at periphery) were manufactured if there was a head-socket mismatch on templating.

Fig. 2

Vacuum introducer to seat the component. The implant and introducer are coupled using 650 mm Hg negative pressure, through a size-specific implantation plate (supplied with the implant).

Fig. 3

Radiological series of a 53-year-old female ballet dancer and yoga teacher: a) preoperatively; b) at two months; and c) at two years. She presented with right groin pain and a limp, affecting her quality of life and livelihood. She reported reacting to costume jewellery. A lymphocyte transformation test demonstrated a strong positive reaction to chromium. Total hip arthroplasty was offered, but the patient preferred a custom metal-on-crosslinked-polyethylene hip resurfacing arthroplasty. At one year, she had resumed all activities including ballet, pilates, and yoga. At two years, she works as a ballet teacher. Clinically and radiologically, there were no adverse features.

Fig. 4

Radiological series of a 59-year-old male surgeon with an active lifestyle, including rowing, spinning, and gymnastics: a) preoperatively; b) at two months; and c) at one year. He presented with bilateral painful arthritic hips. He refused metal-on-metal hip resurfacing arthroplasty and total hip arthroplasty, and specifically requested a metal-on-crosslinked-polyethylene. Superolateral erosion creating secondary dysplasia required the use of a 10 mm inner diameter–outer diameter difference component on the right side. The more commonly used 6 mm sufficed on the left. At one year, he had returned to previous activity. A radiograph at one year showed grade I heterotopic ossification.

Fig. 5

Radiological series of a 21-year-old female university student: a) preoperatively; b) at two days; and c) at one year. She presented with post-Perthes’ disease bilateral painful hips, with her right hip being the most troublesome. Her presenting condition and young age made her an ideal candidate for a bone-conserving procedure. A custom crosslinked-polyethylene resurfacing was performed with 42 mm/48 mm components. At one year, she was back to sporting activity and has started a career.

Fig. 6

Radiological series of a 50-year-old female expedition travel agent and county golf coach: a) preoperatively; b) immediately postoperatively; and c) at three months. She was unable to work due to pain and requested a hip resurfacing, since her job required maintaining high activity levels. She returned to normal activity at work by three months.

Fig. 7

Radiological series of a custom crosslinked-polyethylene (XLPE) component used in the revision of a metal-on-metal (MoM) resurfacing component for a 63-year-old very active male patient: a) preoperatively; b) at two months; and c) at three years. An ASR (DePuy, Warsaw, Indiana) hip resurfacing arthroplasty (HRA) implanted nine years prior, presented with moderately elevated metal ions and a pseudotumour. He refused revision to a total hip arthroplasty as he wanted to continue his highly active lifestyle. He chose to undergo revision of his metal component to an XLPE component while retaining his well-fixed femoral component, converting his MoM HRA into a metal-on-XLPE HRA. Three years after the operation he continues in his active lifestyle.

Fig. 8

Radiological series of revision of an existing Birmingham Hip Resurfacing (BHR; Smith & Nephew, Memphis, Tennessee) component in a 46-year-old male carpenter: a) postoperatively; and b) at one year. He had undergone a 46 mm/52 mm BHR 17 years earlier. Excess component inclination had resulted in high ions. Due to workplace demands, he was considered high-risk for a total hip arthroplasty. Revision to metal-on-crosslinked-polyethylene hip resurfacing arthroplasty using a 56 mm crosslinked-polyethylene component was performed while retaining the femoral component. He is pleased with the outcome and with reducing ion levels at 18 months.