Orthopedics

Feature Article 

Ceramic-on-ceramic Total Hip Arthroplasty: Incidence and Risk Factors of Bearing Surface–related Noises in 125 Patients

Feng-Chih Kuo, MD; Hao-Chen Liu, MD; Wun-Schen Chen, MD; Jun-Wen Wang, MD

Abstract

The ceramic-on-ceramic bearing surface has high wear resistance and good biocompatibility in total hip arthroplasty (THA). However, the postoperative noise problem has been an important issue. The purpose of this retrospective study was to determine the incidence and risk factors of bearing surface–related noises in patients with third-generation ceramic-on-ceramic THAs. One hundred twenty-five patients (143 hips) with ceramic-on-ceramic THAs were included in the study and followed to obtain noise and functional results. Patient factors, including sex, age, height, weight, body mass index, diagnosis, and postoperative range of motion, and surgical factors, including cup inclination, ceramic head size and length, and size of cup related to noises, were recorded. Mean follow-up was 4.2 years (range, 2–10 years). Mean Harris Hip Score was 94 points (range, 68–100 points) at latest follow-up. One (0.8%) patient had radiological evidence of osteolysis, and 4 (3.2%) patients had hip dislocation. No hip sustained a fracture of the ceramic component. Eight (6.4%) patients developed noise at their hips, including clicking in 4, grinding in 2, and snapping in 2. No patient developed squeaking hips or underwent revision surgery because of noisy hips. Younger patients (P=.01), a diagnosis of osteonecrosis (P=.014), a 28-mm ceramic head (P=.042), and a higher hip range of motion postoperatively (P=.001) were related to noise in ceramic-on-ceramic THAs. The study showed third-generation ceramic-on-ceramic THAs had a low incidence of noise problems. However, long-term follow-up is necessary to determine the clinical relevance.

Drs Kuo, Liu, Chen, and Wang are from the Department of Orthopaedic Surgery, Kaohsiung Chang Gung Memorial Hospital and Chang Gung College of Medicine, Kaohsiung, Taiwan, R.O.C.

Drs Kuo, Liu, Chen, and Wang have no relevant financial relationships to disclose.

The authors thank Ya-Ju Yang for the statistical analysis.

Correspondence should be addressed to: Jun-Wen Wang, MD, Department of Orthopaedic Surgery, Kaohsiung Chang Gung Memorial Hospital and Chang Gung College of Medicine, No.123, Dapi Rd, Niaosong District, Kaohsiung City 833, Taiwan, R.O.C. (fongchikuo@adm.cgmh.org.tw).

Abstract

The ceramic-on-ceramic bearing surface has high wear resistance and good biocompatibility in total hip arthroplasty (THA). However, the postoperative noise problem has been an important issue. The purpose of this retrospective study was to determine the incidence and risk factors of bearing surface–related noises in patients with third-generation ceramic-on-ceramic THAs. One hundred twenty-five patients (143 hips) with ceramic-on-ceramic THAs were included in the study and followed to obtain noise and functional results. Patient factors, including sex, age, height, weight, body mass index, diagnosis, and postoperative range of motion, and surgical factors, including cup inclination, ceramic head size and length, and size of cup related to noises, were recorded. Mean follow-up was 4.2 years (range, 2–10 years). Mean Harris Hip Score was 94 points (range, 68–100 points) at latest follow-up. One (0.8%) patient had radiological evidence of osteolysis, and 4 (3.2%) patients had hip dislocation. No hip sustained a fracture of the ceramic component. Eight (6.4%) patients developed noise at their hips, including clicking in 4, grinding in 2, and snapping in 2. No patient developed squeaking hips or underwent revision surgery because of noisy hips. Younger patients (P=.01), a diagnosis of osteonecrosis (P=.014), a 28-mm ceramic head (P=.042), and a higher hip range of motion postoperatively (P=.001) were related to noise in ceramic-on-ceramic THAs. The study showed third-generation ceramic-on-ceramic THAs had a low incidence of noise problems. However, long-term follow-up is necessary to determine the clinical relevance.

Drs Kuo, Liu, Chen, and Wang are from the Department of Orthopaedic Surgery, Kaohsiung Chang Gung Memorial Hospital and Chang Gung College of Medicine, Kaohsiung, Taiwan, R.O.C.

Drs Kuo, Liu, Chen, and Wang have no relevant financial relationships to disclose.

The authors thank Ya-Ju Yang for the statistical analysis.

Correspondence should be addressed to: Jun-Wen Wang, MD, Department of Orthopaedic Surgery, Kaohsiung Chang Gung Memorial Hospital and Chang Gung College of Medicine, No.123, Dapi Rd, Niaosong District, Kaohsiung City 833, Taiwan, R.O.C. (fongchikuo@adm.cgmh.org.tw).

Many alternative bearing surfaces have been used in total hip arthroplasty (THA) in recent years. Ceramic-on-ceramic is a bearing surface with the advantages of extreme hardness, scratch resistance, improved lubrication that creates a low coefficient of friction and results in excellent wear resistance, and less bioactive particulate debris compared with polyethylene or metal in THAs.1,2 The short- to mid-term clinical results of a new generation of alumina ceramic-on-ceramic bearings in young, active adults have been promising.3–5 However, a new problem with squeaking in patients with third-generation ceramic-on-ceramic THAs has recently been encountered. The reported incidence of squeaking after ceramic-on-ceramic THA has ranged between 2.7% and 20.9%.6–8 Some patients required a revision procedure because of the problematic noise.8

The purpose of the current study was to retrospectively review the clinical results of third-generation ceramic-on-ceramic THAs with a specific focus on the noises related to ceramic bearings and their risk fractors.

Materials and Methods

Institutional review board approval (100–1089B) was obtained for this study. One hundred thirty-one consecutive patients who underwent ceramic-on-ceramic THAs between September 2000 and December 2008 were retrospectively reviewed. All THA components were from a single manufacturer (Perfecta; Wright Medical Technology, Inc, Arlington, Tennessee). The ceramic bearing components were Biolox Forte (CeramTec Medical Products, Plochingen, Germany). The ceramic liner and shell were assembled by impacting the ceramic insert into the shell without a titanium elevated rim. The shell/insert group size scheme was that if the cup diameter was 50 mm or less, the size of the ceramic head was 28 mm; if the cup diameter was between 52 and 62 mm, the size of the ceramic head was 32 mm; and if the cup diameter was 64 mm or more, the largest ceramic head (36 mm) was used.

Patient age, sex, height, weight, body mass index (BMI), diagnosis, unilateral or bilateral surgery, surgery site, cup and head size, neck length, and postoperative complications were recorded. Of the original 131 patients, 5 were lost to follow-up and 1 died from unrelated causes 3 years postoperatively. The remaining 125 patients (143 hips) were followed for more than 2 years and were included in the study. Sixty-eight men and 57 women had an average age of 49.4 years (range, 21–76 years). All variables of interest were available for all 125 patients. Average BMI was 25.57 kg/m2 (range, 15.82–37.46 kg/m2); 50 (40%) patients were overweight (BMI more than 25 kg/m2) and 16 (12.8%) were obese (BMI more than 30 kg/m2). Mean follow-up was 4.2 years (range, 2–10.2 years). The most common diagnosis was osteonecrosis of the femoral head (76 patients; 60.8%), followed by osteoarthritis (39 patients; 31.2%), rheumatoid arthritis (8 patients; 6.4%), and ankylosing spondylitis (2 patients; 1.6%).

Surgery was performed by a single experienced surgeon (J.W.W.) through a posterior approach. The optimal inclination and anteversion of the cup was 40° to 45° and 15° to 25°, respectively. All cup and stem components were cementless. Posterior capsulorrhaphy was performed to prevent postoperative hip dislocation.

Clinical Evaluation

Outcome measurements were the Harris Hip Score and hip range of motion (ROM), which were obtained at latest follow-up for all patients. All patients were asked additional questions specifically regarding noise from their hips, including when it started, the frequency of the noise, and daily activities related to the noise. Any radiolucencies around the acetabular component in the zones described by DeLee and Charnley9 and those around the femoral component according to Sarmiento and Gruen10 were reported.

Statistical Analysis

Univariate analysis was used to assess differences in demographic and implant variables between noisy and non-noisy THAs. Chi-square test was used to assess group differences in categorical variables, including sex, surgery site, diagnosis, unilateral or bilateral surgery, head size, neck length, and complications. Mann-Whitney U test was used to compare continuous variables, such as age, height, body weight, BMI, postoperative Harris Hip Score and hip ROM, cup size, and cup inclination. A P value less than .05 was considered significant.

Results

After a mean follow-up of 4.2 years (range, 2–10.2 years), mean postoperative HHS was 94 points (range, 68–100 points) at latest follow-up. Most (92%) patients were highly satisfied (Harris Hip Scores of 90 or more) with their ceramic-on-ceramic THAs. The patient with the lowest Harris Hip Scores also had severe arthritis of both knees. Mean hip ROM at latest follow-up was 111.32° (range, 60°–140°). Regarding femoral head size, 32-mm heads were used in 74 patients and 28-mm heads in 51 patients. Eighty (64%) patients could squat at latest follow-up. Average cup inclination was 42.8° (range, 35.2°–53.7°).

The radiographic results revealed no acetabular cup and 1 stem with evidence of loosening. The exception was a patient with gastric lymphoma with bone metastases to the left acetabulum. The acetabular component developed aseptic loosening 2 years after uncemented THA. The patient was successfully treated by revision THA with a cemented acetabular component and a new ceramic insert and femoral head.

Noisy hip was found in 8 (6.4%) patients, including a clicking sound in 4, a grinding sound in 2, and a snapping sound in 2. No patient reported squeaking. Mean time to development of the first incidence of noise was 21 months postoperatively (range, 3–60 months). One patient developed a snapping sound at 3 months, when he started to ambulate without support. One patient experienced occasional clicking while getting up from bed. After walking, the clicking sound disappeared. A grinding sound was experienced in 1 patient when he moved his hips while brushing his teeth and in another patient when rising up from the toilet. However, these noises occurred infrequently, approximately once every 2 to 3 months. Of these patients, 6 had 28-mm ceramic heads and 2 had 32-mm ceramic heads. Mean ROM of these noisy hips was 124° (range, 110°–135°). Most patients reported that they rarely or occasionally heard these noises and that the noises were not heard by other people. No patient with a noisy hip reported that the noise affected their quality of life, and no patient underwent a revision procedure because of a noisy hip.

Patient age, diagnosis, smaller ceramic head, and postoperative hip ROM were associated with the development of noise. The noise incidence was higher in younger patients (P=.01), those with a diagnosis of avascular necrosis of the femoral head (P=.014), those with a 28-mm head (P=.042), and those with greater hip ROM (P=.001). Sex, height, weight, BMI, and surgery site were not related to the noise. Other implant factors (eg, cup size, neck length, and cup inclination) did not differ between patients with and without noisy hips (Table).

Factors Related to Noisy and Non-noisy Hips

Table: Factors Related to Noisy and Non-noisy Hips

Complications included hip dislocation in 4 (4%) patients, 3 of whom had a 28-mm head and 1 of whom had a 32-mm head. Two of these patients underwent revision THA. One had excessive anteversion of the acetabular component; during revision surgery, the surgeon adjusted the cup orientation to an optimal position. The other patient had inadequate anteversion of the acetabular component and excessive anterior osteophyte formation at the femoral neck, causing bony impingement to the anterior rim of the acetabulum in hip flexion and adduction, and repeated posterior dislocation of the hip. The surgeon changed the acetabulum position to a 40° inclination and 30° anteversion. Periprosthetic fractures occurred in 3 patients and sciatic nerve injury in 2. Follow-up revealed that no hip sustained a ceramic component fracture. No infections occurred.

Discussion

Ceramic-on-ceramic THA bearings have shown low wear rates and excellent clinical results in previous studies.11,12 The 10-year survival rate of the alumina-on-alumina hip prostheses was reported to be 90.8% to 99.0%.13,14 However, squeaking has been considered a relevant complication after ceramic-on-ceramic THAs since 2007.7,15 Factors reported to be related to squeaking include patient,15 surgical,6 postoperative ROM,16,17 and implant factors,18,19 and those inherent to the bearing surface itself, such as microseparation,8 lubrication disruption,20 metal transfer, and a third-body mechanism.21 The exact etiology of squeaking remains unclear and may be multifactorial. According to a large, recently published study, squeaking hips are related to taller, heavier, and younger patients, a higher range of postoperative internal and external rotation, and a higher level of activity.17

The origins of noise generation are unknown. Taylor et al20 designed a laboratory study simulating head subluxation across the ceramic rim to address whether wear stripe formation could be affected by component design or material. They suggested that lubrication conditions and contact stress might play a role in squeaking.20 A biomechanical study demonstrated that squeaking is a problem of ceramic-on-ceramic lubriation, and that this noise occurs when the film fluid between 2 surfaces is disrupted. Material (metal) transfer was the only condition that reproduced squeaking in that study.22

Implant design is considered a possible contributor to squeaking. Most reports of squeaking after ceramic-on-ceramic THAs used the Trident PSL cup (Stryker Orthopaedics, Mahwah, New Jersey).18,23,24 The Trident PSL cup has an elevated metal rim with a ceramic insert encased in a titanium shell that extends past the ceramic insert. This design may lead to earlier femoral neck impingement and joint subluxation, which may cause metal transfer to the ceramic head.19 However, the Lineage Acetabular Cup system (Wright Medical Technology, Inc), which has a ceramic insert seated flush to the titanium shell, was used in the current study. Swanson et al19 reported a 0% (0/29 patients) incidence of squeaking using the Lineage Acetabular Cup. Another study reported a 6% incidence of squeaking using a cup with an elevated titanium rim design.25 However, no squeaking was observed in cups without an elevated titanium rim,25 which is compatible with the current study. Therefore, using an acetabular component without an elevated titanium rim could lead to less squeaking in ceramic-on-ceramic THAs.

Other noises, such as clicking, grinding, and snapping, have been reported in previous studies.4,24,26,27 Schroder et al24 reported an 11% incidence of noisy hip; fewer than 2% of patients reported hearing an audible squeak. Baek and Kim4 reported a 20% (14 hips) incidence of noisy hip; however, only 1 hip experienced squeaking, and the other 13 hips (12 patients) had a click that did not affect their activities of daily living compared with patients without a click. Among those studies, the risk factors related to the occurrence of these noises other than squeaking were not mentioned. In the current study, the incidence of these noises was 6.4%, including clicking (n=4), grinding (n=2), and snapping (n=2), and was related to younger patients, a diagnosis of osteonecrosis, a small femoral head (28 mm), and a higher hip ROM (P<.05).

Noise other than squeaking may be related to the hard landing of the hard-on-hard bearing. The impact of the 2 ceramic surfaces at heel strike could be interpreted by the patient as a click, pop, or snap. Other noise might also be related to soft tissue impingement or shifting, such as with a snapping iliotibial band.28 Stafford et al16 recently reported 6 patients among 250 ceramic-on-ceramic THAs who described grinding or clicking noises that were mostly related to deep flexion. This implies that the generation of noises other than squeaking is somewhat similar to that of squeaking (ie, subluxation of the femoral head posteriorly, resulting from anterior impingement).16

In the current study, patients with noisy hips tended to be younger, with a higher ROM and a smaller femoral head (28 mm), indicating greater joint laxity of the hips as a result of early motion and a higher level of activity. One of 8 patients with noisy hips had a posterior dislocation of the hip postoperatively, and the other 7 patients likely had subluxation of the hip during some activities, causing the noise. The smaller femoral head may aggravate this phenomenon.

One study reported a high rate of revision for dislocation in ceramic-on-ceramic THAs if the head was smaller (28 mm or less) and used in younger patients.29 With the use of a larger femoral head (32 mm, as reported in the current study), the possibility of impingement will be reduced as long as an optimum position for the acetabular component is achieved.15

Conclusion

In this retrospective study of 125 patients undergoing a third-generation ceramic-on-ceramic THA with a mean follow-up of 4 years, a 6.4% incidence of noisy hips existed, and these were related to younger patients, a diagnosis of avascular necrosis of the femoral head, a 28-mm ceramic head, and a higher postoperative hip ROM. No patient developed a squeaking noise, and no patient required revision surgery because of noise. Aside from the noise, the authors’ experience with third-generation ceramic-on-ceramic THAs has resulted in highly satisfactory results and acceptable complication rates. However, further study is necessary to observe the effect of the noises on the clinical outcome.

References

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Factors Related to Noisy and Non-noisy Hips

FactorPatients With Noisy Hips (n=8)Patients With Non-noisy Hips (n=117)P
Sex, No.
  Male464.796
  Female453
Mean age (range), y39.5 (23–60)52.2 (21–76).01
Mean height (range), m1.61 (1.48–1.70)1.61 (1.43–1.83).959
Mean weight (range), kg62.75 (40–81)66.49 (45–105).647
Mean BMI (range), kg/m223.96 (16.02–30.48)25.49 (17.94–39.47).486
Diagnosis, No.
  AVN769.014
  OA039
  RA08
  AS11
THA, No.
  Bilateral216.324
  Unilateral6101
Mean acetabular shell diameter (range), mm49.25 (46–52)52.21 (46–58).181
Femoral head, No.
  32 mm272.042
  28 mm645
Neck, No.
  Short689.273
  Medium125
  Long13
Mean postop HHS95.594.35.992
Mean postop ROM124111.001
Mean cup inclination, deg43.51 (39–47.9)43.38 (35.2–53.7).677
Complication, No.
  Dislocation13.644
  Periprosthetic fracture03
  Sciatic nerve injury02
  Aseptic loosening01

10.3928/01477447-20121023-12

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