Pending Failure in Hard-hard Total Hip Arthroplasty
Pending Failure in Hard-hard Total Hip Arthroplasty
During last 6 years approximately 10.000 ceramic balls and 5.000 ceramic liners have been
 implanted in the region Emilia-Romagna in Italy (4 million Every single year approximately
 60.000 hip prostheses are implanted in Italy. Quality of life of patients after surgery is
 very good, as widely demonstrated in the literature. On the basis of data produced by the
 only complete hip register in Italy that is run in our Lab (RIPO, Register of Orthopedic
 Implants in the Region Emilia-Romagna) survival rate of primary total hip prosthesis is 95.6%
 at 9 years. Reasons for revision are mainly aseptic loosening of one or both components (40%
 of the total) and dislocation (26%), being the latter much more frequent in the first two
 years. Less frequently revision is due to sepsis (7% of the total),bone fracture (11%),
 prosthesis fracture (3%) or pain (3%). Revision is relates, among the others, to
 prosthesis-related factors, such as fixation to bone and articular coupling. In our
 experience, during the last ten years 32% of implants had both articular component in ceramic
 , 34% had metal head and plastic liner, 24% ceramic head and plastic liner, 10% both
 components in metal.

 Each solution has strengths and weakness and they have been identified and clinically applied
 in order to overcome step by step limitations observed in the previous one. The most recent
 are the hard-on-hard bearings, that is ceramic on ceramic and metal on metal. These two
 solutions, beside very promising results on wear resistance, show some peculiar failures:
 respectively fracture of the ceramic component and hypersensitivity induced by metal ions.

 Aim of research proposal is to investigate two uncommon and less investigated early symptoms
 of failure:

 -  'noising hip' in ceramic on ceramic total hip arthroplasty

 -  pain without radiographic signs of loosening in metal on metal total hip arthroplasty
 These two situations are extremely relevant, as they prelude to a failure of the
 prosthesis. If clearly identified they could represent a powerful tool in early
 diagnosis of pending failure To reach this goal our patients wearing hard-on-hard total
 hip arthroplasty, suffering for described symptoms will undergone a specific diagnostic
 procedure.

 The first group will be studied through CT scan of the patients to evaluate impingement or
 instability of the prosthesis, and a needle aspiration for synovial fluid. The fluid will be
 examined to identify ceramic wear debris, according to a method of separation and analysis in
 scanning electron microscopy that was set in our Lab.

 Sound will be recorded by means of a wearable sensor set capable of recording the articular
 noise produced during level walking. This instrumentation will be coupled to motion analysis
 technology.

 This would make possible a diagnostic approach able to correlate the involved factors to
 clinical occurrences, on the basis of the recorded frequencies.

 -Second group will be studied through the dosage of circulating ions, deriving from the
 articular surfaces and through the histological classification of vasculitis in periimplant
 tissues. There is increasing evidence, indeed that locale release of submicron particles worn
 out from articular surfaces can release metal ions (mainly Chromium and Cobalt) responsible
 for lymphocyte local infiltration. In particular CD20 positive B lymphocyte and CD3 positive
 T lymphocyte and sometimes CD68 positive plasma cells are present. The cells could justify
 the development of pseudotumors in metal-on metal hip prosthesis.

 Data collected from patients matched to in vitro results will allow us to to avoid or at
 least propose a more appropriate timing for revision surgery.
Every single year approximately 60.000 hip prostheses are implanted in Italy. Quality of life
 of patients after surgery is very good, as widely demonstrated in clinical experience and in
 the literature. On the basis of data produced by the only complete hip register in Italy,
 that is run in our Lab (RIPO, Register of Orthopedic Implants in the Region Emilia-Romagna
 http://ripo.cineca.it) survival rate of primary total hip prosthesis is 95.6% at 9 years.
 Reasons for revision are mainly aseptic loosening of one or both components (40% of the
 total) and dislocation (26%), being the latter much more frequent in the first two years.
 Less frequently revision is due to sepsis (7% of the total),bone fracture (11%), prosthesis
 fracture (3%) or pain (3%).

 Revision can be related, among the others, to prosthesis-linked factors, such as fixation to
 bone and articular coupling.

 In the experience of RIPO, during the last ten years 32% of implants had both articular
 component in ceramic, 34% had metal head and plastic liner, 24% ceramic head and plastic
 liner, 10% both components in metal.

 Each solution has strengths and weakness and they have been identified and clinically applied
 in order to overcome step by step limitations observed in the previous one.

 Alumina ceramic-on-ceramic (COC) bearings have been shown to produce substantially less wear
 debris than traditional metal/ceramic on polyethylene bearings. In addition, the alumina
 ceramic material itself is essentially bioinert in both bulk and particulate form . Unlike
 metal-on-metal bearings (MOM), this bearing couple does not release metal ions into the body
 either from the articulation or from breakdown of wear debris. Weakness of ceramic-on-ceramic
 bearings are represented by brittleness of the material. Ceramic can fracture, even in very
 few cases, due to trauma or to malpositioning. Beside this occurrence of noise during gait of
 patients can be extremely disturbing for patient itself, leading to request of revision.
 These two solutions represent more recent proposal that technology suggested to overcome
 problem of wear.

 Hard components on plastic has the unsolved problem of wear debris, leading to osteolysis and
 consequent failure of he im plant. The problem has only partially solved by the introduction
 of cross linked polyethylene, aimed to improve tribological behaviour of the plastic.

 Rizzoli Institute is the only public mono-specialistic research hospital in Italy. Nearly 500
 hip prosthesis revisions are performed here every year in the structure. Due to its high
 specialization difficult cases from all the country are treated here, not on ly when anatomy
 of the patient is damaged (dislocation of the hip, post traumatic arthritis) but .even more
 frequently when failure of the implant occurred.

 Aim of research proposal is to investigate two uncommon and less investigated early symptoms
 of failure:

 -  'noising hip' in ceramic on ceramic total hip arthroplasty

 -  pain in metal on metal total hip arthroplasty Even if not numerically so important,
 these two situations are extremely relevant, as they prelude to a failure of the
 prosthesis. If clearly identified they could represent a powerful tool in early
 diagnosis of pending failure.

 The first point will be studied through CT scan of the patients to evaluate impingement or
 instability of the prosthesis, and a needle aspiration for synovial fluid. The fluid will be
 examined to identify ceramic wear debris, according to a method of separation and analysis in
 scanning electron microscopy that was set in our Lab.

 Sound will be recorded by means of a wearable sensor set capable of recording the articular
 noise produced during level walking. This instrumentation will be coupled to motion analysis
 technology, so as to provide a temporal correlation between the recorded noise and the gait
 cycle. It will be developed in the first phase of the project. In parallel surface analyses
 will be conducted on retrievals that are stored in the Lab since 2000, in one of the biggest
 retrieval study ever conducted in our country. Type of damage, surface roughness of both
 ceramic components will be analysed and compared to clinical data.

 Finally the study will be completed in vitro, using an hip simulator, to reproduce the
 possible clinical scenarios leading to hip noise, record, and analyse it in a reproducible
 and robust manner. This would make possible a diagnostic approach able to correlate the
 involved factors to clinical occurrences, on the basis of the recorded frequencies. Second
 point will be studied through the dosage of circulating ions, deriving from the articular
 surfaces and through the histological classification of vasculitis in periimplant tissues.
 There is increasing evidence, indeed that locale release of submicron particles worn out from
 articular surfaces can release metal ions (mainly Chromium and Cobalt) responsible for
 lymphocyte local infiltration. In particular cluster of differentiation antigen 20 (CD20)
 positive B lymphocyte and cluster of differentiation 3 (CD3) positive T lymphocyte and
 sometimes cluster of differentiation antigen 68 (CD68) positive plasma cells are present. The
 cells could indicate a specific phlogistic condition responsible for pain and eventually
 subsequent revision.

 Data collected on studied population will allow a better understanding of the two phenomena
 and possibly will suggest new therapeutic approaches to the problems.
Inclusion Criteria:

 -  Patient waiting for primary total hip arthroplasty (THA)

 -  Patients MoM and CoC referring to our ward

 -  Informed consent approved

 -  Questionnaire on habits filled

 Exclusion Criteria:

 -  Sepsis or suspected sepsis

 -  Patients exposed to other font of metals