Aseptic loosening of the Monk hip prosthesis

In a preliminary report concerning 104 Monk arthroplasties satisfactory results were found within an observation time of 1.6 years (Hansen & Rechnagel 1977). However an early tendency for aseptic loosening was recorded. At a follow-up of the same patients after 5 years it was found that 17 patients, with their primary prostheses in place, had died. Of the remaining 86 prostheses not less than 50% had been removed because of loosening causing symptoms. Furthermore at re-examination of 39 patients with 43 of the primary prostheses still in situ radiological and clinical evidence of progressive aseptic loosening was present. The aetiology of the loosening is discussed and it is suggested that wear of the polyethylene cap plays an important role. It is concluded that the "soft top" Monk prosthesis cannot be recommended for replacement arthroplasty of the hip.