Introduction

Correct postoperative leg length restoration is among the most important goals of hip arthroplasty. Therefore, we developed, validated and clinically applied a novel software algorithm based on surgical navigation, which allows the surgeon to restore a defined femur position without establishing a femoral coordinate system or the hip joint center and measure the leg length accurately and simply.

While alumina ceramic-ceramic THA has been performed in the US for more than 12 years, the phenomenon of frequent, clinically reproducible squeaking is relatively new. The current study investigates the influence of implant design on the incidence of squeaking.

We reviewed implant information on 1275 consecutive revision THAs performed from 10/2002 through 10/2007 to identify any patients who had complained of squeaking or grinding. We also identified, 2778 consecutive primary ceramicceramic THA. Of these, we reviewed the clinical records of 1,039 patients (37%) to date. Any patient complaint of squeaking or grinding at the time of an office visit or by phone interview was recorded. Hips were divided into group 1: flush mounted ceramic liner; group 2a: recessed ceramic liner mated with a stem made of TiAlV and using a 12/14 neck taper; and group 2b: recessed ceramic liner mated with a stem made of a beta titanium alloy comprised of 12% molybdenum, 6% Zirconium, and 2% Iron and using a neck taper smaller than a 12/14 taper.

Of the revision THAs, 5 hips (0.4%) were in patients who had complained of squeaking or grinding. All 5 hips had a recessed, metal-backed ceramic liner and evidence of metallosis. In primary THAs, Group 2b had statistically significantly (p=0.04) more squeaking (7.6%) than group 2a (3.2%) which had statistically significantly (p=0.002) more squeaking than group 1 (0.6%).

Squeaking following ceramic-ceramic THA is associated with use of a recessed metal-backed ceramic liner in combination with a femoral component made of a betatitanium alloy and using a relatively small head-neck taper. Since all revised hips in our study had metallosis, it is possible that metal debris is adversely affecting the bearing and that the elevated metal rim combined with a small head neck taper and the beta-titanium alloy contribute to this problem. Use of bearings with a flush-mounted ceramic liner mated with femoral components made of TiAlV and using a 12/14 taper appears to be prudent.

Patients who are less than 50 years old at the time of total hip arthroplasty (THA) have been known to have higher failure rates than patients who are older. Wearinduced osteolysis and associated component loosening is the most common mode of failure reported. The current investigation prospectively assessed the survivorship and clinical results of alumina ceramic-ceramic THA in patients younger than 50 years.

238 consecutive hips in 201 patients treated by alumina ceramic-ceramic THA were studied. The mean age at operation was 41.4 ± 7.5 years (range, 18 – 50 years).

The preoperative Merle d’Aubigné score was 11.1 ± 1.6 (6 – 15). The preoperative diagnosis included primary osteoarthritis or impingement (105 hips, 44%), developmental dysplasia of the hip (90 hips, 38%), osteonecrosis of the femoral head (17 hips, 7%), post-traumatic osteoarthrosis (16 hips, 7%), and rheumatoid arthritis (6 hip, 3%). 144 hips (61%) were replaced with the use of surgical navigation for acetabular component positioning. The mean cup diameter was 51.8 ± 3.7 (range, 46 – 60 mm). 73 (31%) bearings were 28 mm and 165 (69%) bearings were 32 mm.

At mean follow-up of 5.6 ± 2.3 years (2 – 11 years), the mean Merle d’Aubigné score was 17.4 ± 0.9 (14 – 18). There were no radiographic signs of osteolysis. There were two revisions (0.8%): one for acute cup displacement and one for a ceramic liner fracture. In addition, one hip was treated by I& D for acute infection and another with I& D but without evidence of infection. Other complications included one greater trochanter fracture and one calcar fracture, both repaired at surgery, and one transient peroneal nerve palsy. The 10-year Kaplan Meier survivorship of the implants (revision of any component for any reason) was 98.7% (95% confidence interval 96.3–100%). There were no hip dislocations.

Results of THA in patients less than 50 years using alumina ceramic-ceramic bearings at two to eleven years follow-up are promising with no case of osteolysis or dislocation.

Alumina ceramic-ceramic bearings have the benefit of very low wear and studies showing the complete absence of osteolysis during the first decade of close study. However, good results depend on several critical factors including surgical exposure, surgical technique, component placement, and choice of component design. The following abstract discusses our experience with several of these factors.

Initially, there were concerns that the use of ceramic-ceramic bearings would lead to a higher incidence of hip dislocation since the bearings have fewer femoral head-length choices and the absence of lipped-liners. In our prospective study of 418 hips the incidence of hip dislocation at 1 to 10 year followup is 0.5% (2/418). This experience suggests that the use of alumina ceramic-ceramic bearings is not associated with an increased incidence of dislocation.

More recently, concerns about squeaking of alumina ceramic-ceramic bearings have been reported, particularly from centers in the United States. To investigate this issue, we reviewed information on 1275 consecutive revision THAs and 1039 consecutive primary ceramic-ceramic THA that had been performed at two institutions between 1996 and 2007. To identify the influence of the implant design on the incidence of squeaking we divided the primary hips into three groups with group 1: flush mounted ceramic liner; group 2a: recessed ceramic liner mated with a stem made of TiAlV; and group 2b: recessed ceramic liner mated with a stem made of a beta titanium alloy comprised of 12% molybdenum, 6% Zirconium, and 2% Iron.

Analysis of the 1275 revision hips revealed 5 alumina ceramic-ceramic hips in patients who complained of squeaking or grinding. All 5 hips were designs that included a ceramic liner that was recessed inside of an elevated metal rim. All 5 hips also demonstrated metallosis at the time of revision.

In primary THA, Group 2b had statistically significantly more squeaking (9 of 118) than group 2a (10 of 321) which had statistically significantly more squeaking than group 1 (6 of 700). In addition, the severity of squeaking between the groups was qualitatively different. Patients in Group 2b who complained of squeaking would often experience squeaking frequently throughout the day and could be demonstrated in the physician’s office. By contrast, patients in Group 1 who noted squeaking stated that the hip squeaked once a day to once a year. No patient in Group 1 complained of frequent squeaking or could demonstrate squeaking in the physicians’ office. Further, joint fluid analysis from a patient in Group 2b who complained of squeaking revealed metal from both the femoral (Molybdenum) and acetabular (Aluminum) components.

As reported in another abstract at this meeting, 10 year survivorship of flush-mounted alumina ceramic-ceramic THA is 98.4% (95% confidence interval 97.1–100%) and no patient in that prospective clinical studies demonstrated radiographic evidence of osteolysis or wear.

These experiences demonstrate that THA using alumina ceramic-ceramic is extremely reliable with low revision and dislocation rates and an absence of osteolysis. Significant squeaking is not associated with flush-mounted alumina ceramic liners and is clearly associated with elevated metal rims and metallosis. Finally, squeaking is statistically significantly associated with femoral components made of a beta titanium alloy consisting of Titanium, Molybdenum, Aluminum, and Iron.

Traditional total hip arthroplasty (THA) using metal-on-polyethylene bearings has been established as a reliable procedure but wear and wear debris-associated osteolysis are among the most frequent reasons for revision. Ceramic-ceramic bearings represent an alternative for THA with improved wear characteristics and low biological reactivity of wear particles. We investigated the clinical outcome of alumina ceramic-ceramic THA in a series of more than 400 THAs.

A total 418 alumina ceramic-ceramic THAs performed in 360 patients treated between 1997 and 2007 were studied prospectively. All patients had an uncemented titanium acetabular component with a flush mounted alumina ceramic-ceramic bearing (Wright Medical Technology, Inc. and Ceramtec AG). The mean age at operation was 51.7 ± 12.3 years (range, 18 – 79 years). 47 cases (11%) had previous hip surgery. The indication for surgery included primary osteoarthritis or impingement (58%), developmental dysplasia of the hip (32%), osteonecrosis of the femoral head (5%), post-traumatic osteoarthrosis (2%), and other indications (3%). In 202 (48%) a minimally invasive approach, the superior capsulotomy, was used with the help of the surgical navigation for acetabular component placement.

There were no cases of osteolysis or wear. We found 7 (1.1%) implant revisions: 1 acute cup displacement, 1 acetabular liner fracture, 1 case with failure of osseointegration of the cup, and 4 trochanteric wafer nonunions. A dislocation of the hip was found in 2 (0.5%) cases. The 10-year Kaplan Meier survivorship of the implants (revision of any component for any reason) was 98.4% (95% confidence interval 97.1–100%).

The results of alumina ceramic-ceramic THA after one to ten years are promising, especially considering the young age and high incidence of previous surgery in this patient population. The data are especially encouraging since no hip has demonstrated osteolysis. In particular, we are not aware of any other bearing that has shown an absence of lysis and 10 years follow-up. Since many of these patients are quite young, we await further assessment at 15 and 20 years.

Total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH) has been associated with increased rates of complications and revision. Hip instability and wear-induced osteolysis are among the more common and serious of these problems. The current investigation prospectively assessed the clinical results and the survivorship of patients with DDH treated by alumina ceramic-ceramic THA.

We investigated 164 consecutive hips in 147 patients with DDH. Twenty-five hips (15%) had prior surgery to improve acetabular coverage, 108 hips (66%) were classified as Crowe type I, 21 (13%) as type II, and 10 (6%) as type III. All patients had an uncemented titanium acetabular component with a flush mounted alumina ceramic-ceramic bearing and were treated between 1997 and 2006. The mean age at operation was 48.5 ± 12.2 years (range, 18–75 years). The preoperative Merle d’Aubigné score was 11.3 ± 1.6 (6–15). Ninety-four hips (57%) were replaced with the use of surgical navigation for acetabular component positioning. The mean cup diameter was 51.2 ± 3.9 mm (46–60 mm). Seventy-seven (47%) bearings were 28mm and 87 (53%) bearings were 32mm.

At a mean follow-up of 4.5 ± 2.3 years (2–10 years), the mean Merle d’Aubigné score was 17.5 ± 1.2 (14–18). There were no cases of osteolysis or dislocation. There was one reoperation of an early displaced cup. In addition, there was one calcar crack that was cerclaged, one intraoperative trochanteric fracture also repaired at surgery. No patient complained of squeaking. Ninety-four patients with 100 hips (61%) completed a questionnaire specifically concerning squeaking. None of these patients reported on squeaking either. The 10-year Kaplan Meier survivorship of the implants (revision of any component for any reason) was 99.1% (95% confidence interval 98.0–100%).

Results of ceramic-ceramic THA in young patients with low to middle graded DDH after two to ten year follow-up are promising with no radiographic signs of osteolysis or dislocation.