Range of Motion and Stability in Total Hip Arthroplasty With 28-, 32-, 38-, and 44-mm Femoral Head Sizes An In Vitro Study
TL;DR: Experimental models indicate that larger femoral heads offer potential in providing greater hip ROM and joint stability, and a significant increase in both flexion before dislocation and displacement between the femoral head and acetabulum to produce dislocation occurred with Femoral heads >32-mm in diameter.
Abstract: The purpose of this study was to evaluate, via experimental models, the effect of larger head sizes for total hip arthroplasty on the type of impingement, range of motion (ROM), and joint stability. Testing was conducted using an anatomic full-size hip model (anatomic goniometer) and a novel anatomic dislocation simulator with 28-, 32-, 38-, and 44-mm diameter femoral heads within a 61-mm acetabular shell. Femoral heads >32-mm provided greater ROM and virtually complete elimination of component-to-component impingement. A significant increase in both flexion before dislocation and displacement between the femoral head and acetabulum to produce dislocation occurred with femoral heads >32-mm in diameter. These data indicate that larger femoral heads offer potential in providing greater hip ROM and joint stability.
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TL;DR: A high incidence of squeaking is found in the population of ceramic-on-ceramic noncemented THAs, and it is believed this phenomenon is an underreported side effect of these types of bearings.
Abstract: Ceramic-on-ceramic bearings in THA are a popular alternative to overcome wear concerns in traditional metal-polyethylene bearings. However, squeaking is a potentially worrisome phenomenon in ceramic-on-ceramic THAs which we observed in some of our patients. We reviewed all 42 patients who underwent 43 ceramic-on-ceramic noncemented THAs during the time of the study. Squeaking, defined as a reproducible sound of squeaking, clicking, or grating, occurred in nine of 43 implants (20.9%). Standard radiographs were normal. We used CT imaging to determine cup anteversion and inclination angles, comparing the squeaking hips with those of a randomly selected control group, but found no differences. We then hypothesized specific design features (stem size, cup size, head size, and neck length of the head) would be risk factors for squeaking. We found a difference in neck length between squeaking and nonsqueaking implants. A neck length of −4 mm or shorter resulted in a relative risk of 5.56 (95% confidence interval, 1.14–27.01) for squeaking. We found a high incidence of squeaking in our population, and we believe this phenomenon is an underreported side effect of these types of bearings. A short neck length of the femoral implant was a risk factor for squeaking in ceramic-on-ceramic THA.
Level of Evidence: Level III, therapeutic study.
225 citations
Cites background from "Range of Motion and Stability in To..."
...A shorter neck length results in a smaller range of motion before impingement occurs [3]....
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TL;DR: A large femoral head (36 or 40 mm) reduces dislocation rates in patients undergoing revision THA at short-term followup, and large heads with a highly crosslinked polyethylene acetabular liner are routinely used in all revision THAs.
Abstract: Background
Dislocation after revision THA is a common complication. Large heads have the potential to decrease dislocation rate, but it is unclear whether they do so in revision THA.
164 citations
TL;DR: Early ceramic liner fracture was associated with impingement associated with excessive anteversion of the acetabular cup in Korean patients who habitually squat, resulting in hyperflexion and wide hip abduction.
Abstract: Advances in technology have reduced the risk of fracture of ceramic total hip arthroplasty implants, but concerns remain about fracture of both components. We retrospectively reviewed 133 patients (157 hips) who had cementless alumina-on-alumina total hip arthroplasties with a sandwich-type acetabular component. Six patients (seven hips) died and five patients (six hips) were interviewed by telephone (95% followup). The 122 patients (144 hips) examined had a minimum followup of 36 months (average, 45 months; range, 36-68 months). All acetabular cups and femoral stems were radiographically stable at the last followup. Five hips in five patients (3.5%) were revised because of ceramic liner fractures. Ceramic liner fractures occurred at a mean of 35 months (range, 24-48 months) postoperatively. Acetabular cups in the fracture group (n = 5) were more anteverted than those in the nonfracture group (n = 139). In three patients the fracture apparently occurred during squatting, resulting in hyperflexion and wide hip abduction. Early ceramic liner fracture was associated with impingement associated with excessive anteversion of the acetabular cup in Korean patients who habitually squat.
155 citations
TL;DR: Caution is advised in using larger femoral heads in young or active patients and in those with a low risk of dislocation, and an association between larger (36- and 40-mm) head size and volumetric wear rate and total volumetry wear is observed.
Abstract: Wear of highly cross-linked polyethylene is reportedly independent of head size. To confirm that observation we asked in our population whether head size related to wear with one type of electron beam highly cross-linked polyethylene. Of 146 hips implanted, we evaluated complete clinical and radiographic data for 90 patients (102 hips or 70%). The minimum followup was 5 years (mean, 5.7 years; range, 5–8 years). The head size was selected intraoperatively based on the size of the acetabular component and presumed risk of dislocation. Polyethylene wear measurements were performed in one experienced laboratory using the method of Martell et al. There was no hip with pelvic or femoral osteolysis. The median linear wear rate was 0.028 mm/year (mean, 0.04 mm/year), and the median volumetric wear rate was 25.6 mm3/year (mean, 80.5 mm3/year). Median total volumetric wear was 41.0 mm3 (mean, 98.5 mm3). We found no association between femoral head size and the linear wear rate, but observed an association between larger (36- and 40-mm) head size and volumetric wear rate and total volumetric wear. Although the linear wear rate of polyethylene was not related to femoral head diameter, there was greater volumetric wear (156.6 mm3/year) with the 36- and 40-mm heads. Pending long-term studies of large head sizes, we advise caution in using larger femoral heads in young or active patients and in those with a low risk of dislocation. Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
151 citations
Cites background from "Range of Motion and Stability in To..."
...A reduced risk or elimination of dislocation of hips with larger femoral heads may result from decreased component-component or component-bone impingement and increased translation that is required for hip dislocation [4, 15, 21]....
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...The use of large femoral heads (36, 38, or 40 mm) in THA offers several theoretical advantages, including decreased impingement, increased range of hip motion, and decreased risk of dislocation [4, 5]....
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...The theoretical advantages of larger femoral head sizes are decreased component impingement, increased range of hip motion, and decreased risk of dislocation [4, 21]....
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TL;DR: The ROM improved in a head size-dependent manner primarily because of increasing the jumping distance of the femoral head rather than delaying any impingement, and the effectiveness of femoral offset was driven by delayed osseous impingements.
Abstract: The purpose of this study was to quantify the effects of femoral offset and head size on range of motion (ROM) after total hip arthroplasty. Modular prostheses were implanted into 11 cadaveric hips using a posterolateral approach and tested for ROM with 3 different offsets and 5 different femoral head sizes. Increasing the femoral offset to 4 and 8 mm resulted in 21.1 degrees and 26.7 degrees of improved flexion, and 13.7 degrees and 21.2 degrees of improved internal rotation, respectively. The ROM improved in a head size-dependent manner primarily because of increasing the jumping distance of the femoral head rather than delaying any impingement. In contrast, the effectiveness of femoral offset was driven by delayed osseous impingement.
131 citations
References
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TL;DR: During the ten-year period ending in 1978, 10,500 conventional total hip arthroplasties were performed at the Mayo Clinic; dislocation developed after 331 of these procedures; cross correlations of the data were performed and showed that previous surgery on the hip was the most significant of the factors predisposing to dislocation.
Abstract: During the ten-year period ending in 1978, 10,500 conventional total hip arthroplasties were performed at the Mayo Clinic; dislocation developed after 331 (3.2 per cent) of these procedures. Cross correlations of the data were performed using multivariate analysis. This analysis showed that previous surgery on the hip was the most significant of the factors predisposing to dislocation, the incidence doubling from 2.4 per cent (in hips without previous surgery) to 4.8 per cent (in hips with previous surgery) (p less than 0.001). The dislocation rate was 2.3 per cent after an anterolateral approach and 5.8 per cent after a posterior approach (p less than 0.01). The size of the head of the femoral component was not a strongly influential factor. The incidence of dislocation was 17.6 per cent in the hips that had osteotomy and avulsion of the greater trochanter, compared with 2.8 per cent in those in which the trochanteric osteotomy united (p less than 0.001). Reoperation for instability of the hip was performed in a third of the patients, but in 31 per cent of the patients whose hip was reoperated on the instability persisted after the revision.
1,115 citations
"Range of Motion and Stability in To..." refers background in this paper
...Woo and Morrey [5], reported no difference in dislocation rates between 22-mm heads versus 32-mm heads....
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...Because a majority of dislocation of THAs occurring in vivo are posterior [5], the dislocation testing was conducted in pure flexion....
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...Dislocation of a total hip arthroplasty (THA) is a Between 30% [5,6] and 65% [9,10] of dislocations multifactorial and vexing problem [1]....
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...Among factors correlated with dislocation rates are surgeon and hospital volume [13-15], component malposition [3,5,7,16,17], head/neck ratio [18-21], and the shape of the femoral neck [22] and modular femoral heads with longer neck lengths that require a skirt....
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...8% [4,5] for primaries and from 4....
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Book•
01 Dec 1978
835 citations
"Range of Motion and Stability in To..." refers background in this paper
...Elevated lip liners have been widely used in some form since Charnley first created the long posterior wall socket [32]....
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TL;DR: Patients treated at hospitals and by surgeons with higher annual caseloads of primary and revision total hip replacement had lower rates of mortality and of selected complications.
Abstract: Background: The mortality and complication rates of many surgical procedures are inversely related to hospital procedure volume. The objective of this study was to determine whether the volumes of primary and revision total hip replacements performed at hospitals and by surgeons are associated with rates of mortality and complications.
Methods: We analyzed claims data of Medicare recipients who underwent elective primary total hip replacement (58,521 procedures) or revision total hip replacement (12,956 procedures) between July 1995 and June 1996. We assessed the relationship between surgeon and hospital procedure volume and mortality, dislocation, deep infection, and pulmonary embolus in the first ninety days postoperatively. Analyses were adjusted for age, gender, arthritis diagnosis, comorbid conditions, and income. Analyses of hospital volume were adjusted for surgeon volume, and analyses of surgeon volume were adjusted for hospital volume.
Results: Twelve percent of all primary total hip replacements and 49% of all revisions were performed in centers in which ten or fewer of these procedures were carried out in the Medicare population annually. In addition, 52% of the primary total hip replacements and 77% of the revisions were performed by surgeons who carried out ten or fewer of these procedures annually. Patients treated with primary total hip replacement in hospitals in which more than 100 of the procedures were performed per year had a lower risk of death than those treated with primary replacement in hospitals in which ten or fewer procedures were performed per year (mortality rate, 0.7% compared with 1.3%; adjusted odds ratio, 0.58; 95% confidence interval, 0.38, 0.89). Patients treated with primary total hip replacement by surgeons who performed more than fifty of those procedures in Medicare beneficiaries per year had a lower risk of dislocation than those who were treated by surgeons who performed five or fewer of the procedures per year (dislocation rate, 1.5% compared with 4.2%; adjusted odds ratio, 0.49; 95% confidence interval, 0.34, 0.69). Patients who had revision total hip replacement done by surgeons who performed more than ten such procedures per year had a lower rate of mortality than patients who were treated by surgeons who performed three or fewer of the procedures per year (mortality rate, 1.5% compared with 3.1%; adjusted odds ratio, 0.65; 95% confidence interval, 0.44, 0.96).
Conclusions: Patients treated at hospitals and by surgeons with higher annual caseloads of primary and revision total hip replacement had lower rates of mortality and of selected complications. These analyses of Medicare claims are limited by a lack of key clinical information such as operative details and preoperative functional status.
671 citations
TL;DR: A novel method of increasing the cross-link density is presented in which UHMWPE is irradiated in air at an elevated temperature with a high-dose-rate electron beam and subsequently is melt-annealed, which leads to the absence of detectable free radicals in the polymer and, as a result, excellent resistance to oxidation of the polymer.
Abstract: Increasing cross-linking has been shown in vitro and in vivo to improve markedly the wear resistance of ultra-high-molecular-weight polyethylene (UHMWPE). The reduction in the mechanical properties of polyethylene under certain methods used to produce cross-linking has been a concern, however. These reductions are known to result from the processes used to increase the cross-link density and could affect the device performance in vivo. We present a novel method of increasing the cross-link density of UHMWPE in which UHMWPE is irradiated in air at an elevated temperature with a high-dose-rate electron beam and subsequently is melt-annealed. This treatment improves markedly the wear resistance of the polymer as tested in a hip simulator, while maintaining the mechanical properties of the material within national and international standards. This method leads to the absence of detectable free radicals in the polymer and, as a result, excellent resistance to oxidation of the polymer.
599 citations
TL;DR: The two senior authors (PMP, RP) independently began using an identical enhanced posterior soft tissue repair after total hip replacement through a posterior approach and found that a dislocation rate was reduced in patients before and after the enhanced closure.
Abstract: The two senior authors (PMP, RP) independently began using an identical enhanced posterior soft tissue repair after total hip replacement through a posterior approach. In the first author's experience, a dislocation rate of 4% in 395 patients before using the enhanced closure was reduced to 0% in 395 patients in whom the enhanced closure was performed. In the second author's experience, 160 total hip replacements had a dislocation rate of 6.2% before the enhanced closure whereas 124 total hip replacements had a dislocation rate of 0.8% after the enhanced closure. These results are highly statistically significant.
392 citations
"Range of Motion and Stability in To..." refers background in this paper
...Advances in soft-tissue repair [30,31] and the awareness of proper component orientation have decreased the incidence of dislocation after THA in reports from many teaching centers....
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