CLS Spotorno expansion acetabular cup is in use since 1984 for uncemented Metal-Polyethylene (PE) total hip arthroplasties (THA). Metal-PE articulations are notoriously known to wear and lead to failure of THA. However, catastrophic breakage of expansion acetabular cup is rare. Our 74-year-old male who was diagnosed with bilateral osteonecrosis of femoral head, underwent bilateral THA using CLS Spotorno metal expansion acetabular cups (Protek, AG, Bern) in 1991. He had irregular follow-up since then. In 2005, he presented with right hip pain and inability to walk without support. Anteroposterior (AP) hip radiographs established the diagnosis of catastrophic failure of right THA secondary to severe liner wear and acetabular osteolysis. Patient chose to postpone the revision surgery and opted for wheel chair ambulation. He presented 4 years later, when the right hip pain became unbearable. Anteroposterior as well as lateral hip radiographs showed worsening of cup breakage with superolateral migration of metal femoral head. Pelvic CT scans confirmed severe acetabular osteolysis in DeLee and Charnley's Zone 1, 2 & 3 with secondary loss of bony support to the expansion cup [Fig. 1]. A revision THA was strongly advised. However, patient sought for a pain-free rather than a fully ambulatory right hip and decided against a second THA. We performed resection arthroplasty of right hip with bone cement loading, respecting patient's decision. Intra-operatively, the metal femoral head was lying in the huge osteolytic defect in the roof of acetabulum. The 3 cranial wings of metal expansion shell were broken with corresponding wear of the cranial pole of polyethylene liner [Fig. 2]. We were able to gratify patient's expectations and patient is able to ambulate with the aid of one crutch at latest follow-up. However, it is clearly evident that a timely and regular follow-up would have identified the initial PE wear and secondary osteolysis. Additionally, it can avoid extensive procedures like a revision THA or resection arthroplasty by allowing simple procedures like modular PE liner and the femoral head exchange. A comprehensive review of literature for catastrophic acetabular component breakage revealed 10 such cases, although with different cup designs. To the best of our knowledge, this is the first case of CLS expansion cup breakage for metal-PE articulation. Majority of these cases have a presence of extensive liner wear and pelvic osteolysis along with a post-operative irregular follow up. This case stresses on importance of regular follow-up even after many years of index THA to identify early PE wear and prevent secondary catastrophic complications.

Introduction

Alumina Ceramic liners are increasingly used in patients undergoing Total Hip Replacement (THR). The rate of fracture of ceramic liner is decreasing with improved manufacturing techniques from 1^st to 3^rd generation alumina-ceramic liners. We report the first case of a fracture of a modern, 4^th generation alumina bearing ceramic liner, which incorporates a metal sheath to help avoid fracture. Our case is a 60 years old female presenting two years and three months after a bilateral total hip replacement using Stryker Trident cup, securfit stem and alumina on alumina bearing ceramic liner. Ceramic liners are commonly used, especially in young patients because of their excellent biocompatibility, low wear rate and superior tribology. Although fracture of ceramic liner is a less common complication of modern total hip arthroplasty, it is a major concern with the use of ceramic on ceramic THR, the reason being brittleness of ceramic. Cases of 3^rd generation ceramic liner fracture have been reported which might be associated with impingement due to excessive anteversion of the socket in Asian patients who habitually squat. Habitual squatting, sitting cross legged and kneeling were not characteristic of this case.

Purpose

In an effort to increase the durability of cemented total hip arthroplasties (THA), femoral stems were precoated using polymethlymethacrylate (PMMA). One such design is Harris precoat plus and centralign design (Zimmer, Warsaw, Indiana). The reports on these particular designs are variable, ranging from good survival to early failures, studied over short to medium term. Early failures have been attributed, most of the time to debonding at cement-bone interface. In view of lack of long term and variable results, we reviewed the results of primary hybrid THA performed during October 1990 to December 1995, using a PMMA coated, cemented femoral prosthesis and contemporary cementing techniques.