Small Femoral Head Research Articles

Helical Tomotherapy Delivery of an IMRT Boost in Lieu of Interstitial Brachytherapy in the Setting of Gynecologic Malignancy: Feasibility and Dosimetric Comparison

Interstitial brachytherapy is an important means by which to improve local control in gynecologic malignancy when intracavitary brachytherapy is untenable. Patients unable to receive brachytherapy have traditionally received conventional external beam radiation alone with modest results. We investigated the ability of Tomotherapy (Tomotherapy Inc., Madison, WI) to replace interstitial brachytherapy. Six patients were selected. The planning CT of each patient was contoured with the planning target volume (PTV), bladder, rectum, femoral heads, and bowel. Identical contour sets were exported to Tomotherapy and Nucletron PLATO (Nucletron B.V., Veenendaal, The Netherlands). With Tomotherapy, the PTV was prescribed 31 Gy in 5 fractions to 90% of the volume. With PLATO, 600 cGy × 5 fractions was prescribed to the surface of the PTV. Dose delivered was normalized to 2 Gy fractions (EQD2) and added to a hypothetical homogenous 45-Gy pelvic dose. Tomotherapy achieved a D90 of 87 Gy EQD2 versus 86 Gy with brachytherapy. PTV dose was more homogeneous with tomotherapy. The dose to the most at-risk 2 mL of bladder and rectum with Tomotherapy was of 78 and 71 Gy EQD2 versus 81 and 75 Gy with brachytherapy. Tomotherapy delivered more dose to the femoral heads (mean 1.23 Gy per fraction) and bowel. Tomotherapy was capable of replicating the peripheral dose achieved with brachytherapy, without the PTV hotspots inherent to interstitial brachytherapy. Similar maximum doses to bowel and bladder were achieved with both methods. Excessive small bowel and femoral head toxicity may result if previous pelvic irradiation is not planned accordingly. Significant challenges related to interfraction and intrafraction motion must be overcome if treatment of this nature is to be contemplated.

Outcome of primary resurfacing hip replacement: evaluation of risk factors for early revision

Background and purpose The outcome of modern resurfacing remains to be determined. The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) started collection of data on hip resurfacing at a time when modern resurfacing was started in Australia. The rate of resurfacing has been higher in Australia than in many other countries. As a result, the AOANJRR has one of the largest series of resurfacing procedures. This study was undertaken to determine the results of this series and the risk factors associated with revision.Patients and methods Data from the AOANJRR were used to analyze the survivorship of 12,093 primary resurfacing hip replacements reported to the Joint Replacement Registry between September 1999 and December 2008. This was compared to the results of primary conventional total hip replacement reported during the same period. The Kaplan-Meier method and proportional hazards models were used to determine risk factors such as age, sex, femoral component size, primary diagnosis, and implant design.Results Female patients had a higher revision rate than males; however, after adjusting for head size, the revision rates were similar. Prostheses with head sizes of less than 50 mm had a higher revision rate than those with head sizes of 50 mm or more. At 8 years, the cumulative per cent revision of hip resurfacing was 5.3 (4.6–6.2), as compared to 4.0 (3.8–4.2) for total hip replacement. However, in osteoarthritis patients aged less than 55 years with head sizes of 50 mm or more, the 7-year cumulative per cent revision for hip resurfacing was 3.0 (2.2–4.2). Also, hips with dysplasia and some implant designs had an increased risk of revision.Interpretation Risk factors for revision of resurfacing were older patients, smaller femoral head size, patients with developmental dysplasia, and certain implant designs. These results highlight the importance of patient and prosthesis selection in optimizing the outcome of hip resurfacing.

Subcapital Femoral Neck Fracture following Successful Trochanteric Fracture Treatment with a Dynamic Hip Screw: A Report of Five Cases

A subcapital femoral neck fracture complicating a healed trochanteric fracture is rare. Such cases are managed in a rather heterogeneous manner, i.e. there exists a mixture of cases treated by either fixed angle devices or dynamic compression screws. We describe 5 patients who developed subcapital femoral neck fractures after healed trochanteric fractures treated with dynamic compression screws. The subjects' clinical data, operative records, and radiographs have been studied retrospectively and the literature reviewed. The risk factors for such a complication include being of advanced age, female, osteoporotic, and having a small femoral head and neck, and a basicervical type of fracture.

Thirty-two Millimetre Heads and Accelerated Polyethylene Wear in Total Hip Arthroplasty

In total hip arthroplasty 32 mm heads are often used as the greater diameter is thought to contribute to improved stability. However, greater head diameter can also lead to greater volumetric wear. We compared polyethylene wear between patients with 32 mm heads and those with smaller heads. All patients who had Harris Galante1 metal-backed, uncemented cups inserted between 1986 and 1996 at our institute were annually reviewed clinically and radiographically. Accelerated polyethylene wear was noted between the fifth and seventh postoperative year in 17 out of 165 total hip replacements with 32 mm heads, but only in 21 out of 961 total hip arthroplasties with smaller femoral heads. In all 17 THRs, accelerated wear was also associated with thin polyethylene (<6 mm). This paper highlights a potentially serious problem. When 32 mm metal heads are used with uncemented cups and polyethylene liners, there is a risk of accelerated acetabular wear in patients with thin polyethylene.

Dislocation of the Hip after Reimplantation for Infection

Dislocation is a well documented complication after a two-stage revision arthroplasty for a deep periprosthetic hip infection. We are aware of no reports specifically evaluating the risk factors for dislocation after reimplantation for infection. We hypothesized greater age, increase in the number of operations on the hip, increase in the length of time from resection to reimplantation, greater limb length discrepancy, smaller femoral offset, and using smaller femoral heads would increase the risk of dislocation. We retrospectively reviewed 34 patients who had a two-stage hip revision for periprosthetic infection with a minimum followup of 2 years. Risk factors for dislocation were evaluated. We compared the rate of dislocation in this group to those patients having revision for aseptic failure. Sixteen dislocations occurred in five (14.7%) of 34 patients. Dislocation occurred in three (1.7%) of 171 patients having revision for aseptic failure. In this small series, age at reimplantation, number of previous operations on the hip, length of time from resection to reimplantation, limb length discrepancy, femoral offset, and femoral head size did not seem to be risk factors for dislocation.

Thirty-two millimetre heads and accelerated polyethylene wear in total hip arthroplasty

In total hip arthroplasty 32 mm heads are often used as the greater diameter is thought to contribute to improved stability. However, greater head diameter can also lead to greater volumetric wear. We compared polyethylene wear between patients with 32 mm heads and those with smaller heads. All patients who had Harris Galante1 metal-backed, uncemented cups inserted between 1986 and 1996 at our institute were annually reviewed clinically and radiographically. Accelerated polyethylene wear was noted between the fifth and seventh postoperative year in 17 out of 165 total hip replacements with 32 mm heads, but only in 21 out of 961 total hip arthroplasties with smaller femoral heads. In all 17 THRs, accelerated wear was also associated with thin polyethylene (<6 mm). This paper highlights a potentially serious problem. When 32 mm metal heads are used with uncemented cups and polyethylene liners, there is a risk of accelerated acetabular wear in patients with thin polyethylene.

The case is unchanged and remains robust: Australopithecus afarensis exhibits only moderate skeletal dimorphism. A reply to

Previous attempts to estimate body mass in pre-Holocene hominins have relied on prediction equations derived from relatively limited extant samples. Here we derive new equations to predict body mass from femoral head breadth and proximal tibial plateau breadth based on a large and diverse sample of modern humans (avoiding the problems associated with using diaphyseal dimensions and/or cadaveric reference samples). In addition, an adjustment for the relatively small femoral heads of non-Homo taxa is developed based on observed differences in hip to knee joint scaling. Body mass is then estimated for 214 terminal Miocene through Pleistocene hominin specimens. Mean body masses for non-Homo taxa range between 39 and 49 kg (39–45 kg if sex-specific means are averaged), with no consistent temporal trend (6–1.85 Ma). Mean body mass increases in early Homo (2.04–1.77 Ma) to 55–59 kg, and then again dramatically in Homo erectus and later archaic middle Pleistocene Homo, to about 70 kg. The same average body mass is maintained in late Pleistocene archaic Homo and early anatomically modern humans through the early/middle Upper Paleolithic (0.024 Ma), only declining in the late Upper Paleolithic, with regional variation. Sexual dimorphism in body mass is greatest in Australopithecus afarensis (log[male/female] = 1.54), declines in Australopithecus africanus and Paranthropus robustus (log ratio 1.36), and then again in early Homo and middle and late Pleistocene archaic Homo (log ratio 1.20–1.27), although it remains somewhat elevated above that of living and middle/late Pleistocene anatomically modern humans (log ratio about 1.15).

Dissociation of the Harris-Galante II polyethylene liner in rheumatoid arthritis patients

We investigated the dissociation of polyethylene liner from the Harris-Galante II metal shell inarthritis patients with rheumatoid arthritis. A total of 41 total hip arthroplasties using Harris-Galante II cup in 34 patients were reviewed retrospectively. There were three cases with dissociation of the polyethylene liner and locking tine breakage of metal shell, and one case with locking tine breakage without dissociation of the polyethylene liner. In three cases with dissociation of the polyethylene liner, two cups had been placed relatively horizontally while the third had been placed relatively vertically. In general, high activity, heavy body weight, and young age are thought to be risk factors for polyethylene liner dissociation, but these patients generally have lower activity and lighter body weight compared to patients with osteoarthritis or avascular necrosis of the femoral head. The use of small femoral heads and either horizontal or vertical cup placement may have allowed impingement and tine damage, contributing to liner dissociation in these relatively inactive patients.

Total hip replacement in identical twins with Scheie Mucopolysaccharidosis.

Investigation performed at the Hospital for Special Surgery, New York, USA Scheie Syndrome is an autosomal recessive metabolic storage disease with distinct skeletal findings known as "dysostosis multiplex". This paper reports on identical twins with Scheie Syndrome who required total hip arthroplasty for early osteoarthritis of the hip. The surgical approach and exposure was particularly demanding due to the stiffness imposed by the soft tissues arising from infiltration of glycosaminoglycans. The small femoral head and acetabulum limited the diameter of the acetabular component and subsequently the prosthetic head diameter that could be safely utilized without compromising the thickness of the polyethylene liner. Twenty-two millimeter heads with a standard polyethylene insert were therefore utilized in the two arthroplasties performed in 1998 in the first twin, and a 28 mm head with a highly cross linked polyethylene liner, in the arthroplasty performed on the second twin in 2003. This is a relevant issue considering that these patients required an arthroplasty at a young age. Hip arthroplasty relieved pain, improved ambulation and provided a better range of motion in our two patients. There were no peri-operative complications. Long-term survivorship of total hip replacement in this population is not yet known. (Hip International 2005; 15: 55-8).

Total hip replacement in identical twins with Scheie Mucopolysaccharidosis

Investigation performed at the Hospital for Special Surgery, New York, USA Scheie Syndrome is an autosomal recessive metabolic storage disease with distinct skeletal findings known as "dysostosis multiplex". This paper reports on identical twins with Scheie Syndrome who required total hip arthroplasty for early osteoarthritis of the hip. The surgical approach and exposure was particularly demanding due to the stiffness imposed by the soft tissues arising from infiltration of glycosaminoglycans. The small femoral head and acetabulum limited the diameter of the acetabular component and subsequently the prosthetic head diameter that could be safely utilized without compromising the thickness of the polyethylene liner. Twenty-two millimeter heads with a standard polyethylene insert were therefore utilized in the two arthroplasties performed in 1998 in the first twin, and a 28 mm head with a highly cross linked polyethylene liner, in the arthroplasty performed on the second twin in 2003. This is a relevant issue considering that these patients required an arthroplasty at a young age. Hip arthroplasty relieved pain, improved ambulation and provided a better range of motion in our two patients. There were no peri-operative complications. Long-term survivorship of total hip replacement in this population is not yet known. (Hip International 2005; 15: 55-8).

Large versus small femoral heads in metal-on-metal total hip arthroplasty

The recent resurgence of metal-on-metal total hip arthroplasty has afforded the surgeon new options in femoral head diameters that were not previously available. Reduction in the risk for dislocation and potential improvements in articular wear are the obvious advantages of large-diameter femoral heads. Total hips with larger-diameter femoral heads are more resistant to dislocation. The clinical experience with 616 38 mm diameter femoral heads showed no dislocations within the first 3 months after surgery, compared with 2.5% of 78 patients receiving 28 mm diameter femoral heads with otherwise identical components. Use of larger-diameter femoral heads appears to have the potential to substantially reduce the early risk of dislocation of the prosthetic hip arthroplasty.

The influence of head and neck geometry on stability of total hip replacement: a mechanical test study.

Dislocation after replacement may be caused by poor implant design or positioning, or by the surgical approach taken. We evaluated the influence of head and neck design on range of motion and stability (with respect to risk of dislocation) in total hip endoprostheses. Using a test device, we determined the stability afforded by different head sizes and neck geometries for various implant positions. Increasing head diameter led to an enhancement of range of motion as well as resistance against subluxation, and thus to improved stability in any movement combination and implant orientation. Smaller femoral heads were associated with increased risk of dislocation, especially in a poor implant position such as retroversion, and steep positioning of the cup. Skirted metal or mushroom-shaped ceramic heads had a reduced range of motion until impingement of approx. 20 degrees, as compared to spherical standard heads. Furthermore, after identical joint loading, skirted heads dislocated more readily than standard heads with corresponding diameters. To obtain sufficient joint mobility and stability, neck geometry and implant position should be considered when choosing the femoral head size.

Metal Ion Release after a Metal-on-Metal Hip Arthroplasty: Comparison between Resurfacing Arthroplasty and Total Hip Arthroplasty

Purpose: To verify that the metal-on-metal (MOM) surfaces produce metal ions and to ascertain the differences between large and small femoral head diameters with regard to the release of metal ions. Materials and Methods: Forty two cases of MOM hip resurfacing arthroplasty (mean head diameter: 47.1 mm) and 39 cases of conventional total hip replacement arthroplasty (head diameter: 28 mm) were performed at our hospital from June 1998 to April 2003. All the cases were followed-up using the serum cobalt and chromium ion levels. The serum cobalt and chromium ion levels were compared in the 21 cases in each group, which were matched by age, weight and follow-up period. The control group involved 21 patients who had undergone an alumina-alumina total hip arthroplasty. The patient’s serum metal ion concentration was measured from the serum, which had been separated from the whole blood and diluted using inductively-coupled plasma mass spectrometry (Agilent 4500, Rhode Island, USA). Results: All MOM bearing implants produced higher serum levels of cobalt and chromium ions than the control. The serum concentration of cobalt with MOM resurfacing was higher than that observed with a 28 mm MOM total hip arthroplasty (p=0.025), but the chromium levels were not significantly different (p=0.501). Conclusion: The MOM bearing implants in this study produced elevated serum levels of cobalt and chromium ions. In addition, large diameter heads resulted in greater systemic exposure of cobalt ions than the small diameter heads. However, a long-term follow-up will be needed to determine the clinical significance.

Recently identified postcranial remains of Paranthropus and Early Homo from Swartkrans Cave, South Africa

Fifteen newly recognized hominid postcranials from Swartkrans are described here and compared with a sample of previously described early hominids, African apes and modern humans. Ten of the new specimens are from Member 1. Two are from Member 2 and three are from Member 3. Nine of the fossils are referred to Paranthropus, three to Homo, and three specimens cannot be assigned at present.The collection of hominid postcranials from Members 1–3 at Swartkrans now numbers more than 70 specimens. With the description of two new, small femoral heads, SKW 19 and SK 3121, there are now four proximal femora from Swartkrans. When SK 82 and SK 97 are compared with SKW 19 and SK 3121, the two sets offer important insights into body size and sexual dimorphism in Paranthropus robustus.A new distal femur, SK 1896 and other bones attributed to Homo cf. erectus, indicate that male Homo were larger than Paranthropus at Swartkrans.

Review Article: Polyethylene wear and osteolysis in total hip arthroplasty.

Polyethylene wear has been accepted as a major cause of osteolysis in total hip arthroplasty. Submicron particles, which are secondary to abrasive wear, migrate into the effective joint space and stimulate a foreign-body response resulting in bone loss which is mainly mediated by macrophages. Diagnosis depends on serial radiographic evaluation and frequent follow-up. Polyethylene wear and osteolysis can be prevented by reducing the wear such as using a small femoral head, adaptive polyethylene thickness, suitable surgical techniques, non-polyethylene articulation, etc. The presence of cement or circumferential coatings may also retard the distal migration of particles. Medicines such as NSAIDs and bisphosphonate appear to inhibit the progress of osteolysis. As far as treatment, revision surgery is able to reconstruct the joint by replacing partial or total prosthesis and repair the defect by bone grafting according to intraoperative assessment.

The porous-coated anatomic total hip prosthesis, inserted without cement. A prospective study with a minimum of ten years of follow-up.

One hundred consecutive primary total hip arthroplasties performed with use of a porous-coated anatomic total hip prosthesis, fixed without cement, in ninety-one patients were followed prospectively for a minimum of ten years. At the time of the most recent follow-up, twenty patients (twenty-three hips) had died and seventy-one patients (seventy-seven hips) were living. The average age of the living patients was sixty-six years (range, thirty-two to ninety-two years), and their average Harris hip score was 84 points (range, 33 to 100 points). Twelve percent (nine) of the seventy-seven hips were found to be associated with pain in the thigh when the patients were specifically questioned by the examiner. Eleven hips were revised during the follow-up period. Only the acetabular component was revised in six hips, only the femoral component was revised in one hip, and both the femoral and the acetabular components were revised in four hips. Of the ten acetabular revisions, one was performed because of acute dissociation of the component and eight, because of a combination of polyethylene wear, osteolysis, and loosening; the tenth acetabular revision consisted of exchange of the liner and curettage and bone-grafting of the osteolytic area. Of the five femoral revisions, two were performed because of loosening and three, because of extensive osteolysis of the proximal aspect of the femur. Including the revised components, twelve acetabular components and five femoral components had radiographic evidence of aseptic loosening. Acetabular osteolysis occurred in seventeen hips. Femoral osteolysis occurred in thirty-nine hips: in the proximal aspect of thirty-one hips, in the distal aspect of four, and in both the proximal and the distal aspect of four. The durability of the femoral fixation documented in this study is especially encouraging in view of the fact that this was our initial experience with devices fixed without cement and that a so-called first-generation femoral component was used. However, the study also demonstrated that not all acetabular components fixed without cement function well over the long term and that specific design considerations (adequate initial fixation, congruency between the liner and the shell, an optimum shell-liner capturing mechanism, and a smaller femoral head) are warranted.

Total hip arthroplasty performed with insertion of the femoral component with cement and the acetabular component without cement. Ten to thirteen-year results.

Fifty-two consecutive primary total hip arthroplasties were performed in forty-seven unselected patients by one surgeon. The prosthesis included a hemispherical porous-coated acetabular component, inserted without cement and with the use of screws through three peripheral flanges, and a femoral component, inserted with a so-called second-generation cementing technique. No patient was lost to radiographic follow-up, and the clinical result was known for all patients. The average age at the time of the index operation was fifty-seven years (range, twenty-nine to seventy-nine years). Four patients (four hips) who died were last examined less than ten years postoperatively (the minimum follow-up period for this study) and one hip was revised, leaving forty-seven non-revised hips in forty-two surviving patients who were followed for at least ten years. The duration of clinical follow-up of these forty-two patients averaged 12.3 years (range, 10.8 to 13.3 years), and the duration of radiographic follow-up averaged 12.1 years (range, 10.0 to 13.0 years). One (2 per cent) of the original fifty-two hips was revised for late recurrent dislocation, without loosening, 9.7 years after the index arthroplasty. The rate of dislocation was relatively high (13 per cent; seven hips), and we believed it to be related to the shallow-chamfer acetabular design combined with the small femoral head. At the time of the latest follow-up, no femoral component was loose. One (2 per cent) of the fifty-two acetabular components was loose according to radiographic criteria, but the hip functioned well (Harris hip score, 94 points) 12.4 years after the index arthroplasty. Pelvic osteolysis developed in one hip (2 per cent); femoral osteolysis, in eight (15 per cent); and distal femoral osteolysis, in three (6 per cent). The average Harris hip score for the forty-seven non-revised hips increased from 48 points (range, 26 to 63 points) preoperatively to 89 points (range, 67 to 100 points) at the time of the most recent follow-up. Forty (85 per cent) of the forty-seven hips had a good or excellent result, whereas five (11 per cent) had a fair result (score, 74 to 79 points) and two (4 per cent) had a poor result (score, 67 and 69 points). The hybrid primary total hip arthroplasty resulted in very good clinical function at ten to thirteen years, although the rate of dislocation was high.

Increased incidence of arthrosis in women could be related to femoral and pelvic shape.

In this study various femoral and pelvic geometrical parameters important for hip joint contact stress were determined. The parameters were measured from standard anteroposterior radiographs of healthy adult subjects and analysed by using descriptive statistical procedures. Women proved to have a significantly smaller femoral head radius and larger distance between the inner acetabular rims than men, both features which lead to an increase of contact stress in the hip joint articular surface. Since too high, long-lasting contact stress is unfavourable regarding the development of arthrosis, we propose that these differences in the femoral and pelvic geometry could be one of the reasons for the increased incidence of arthrosis in women.

Prosthetic dislocation in customized total hip replacement: a clinical and radiographic review

The incidence of dislocation reported in the literature varies between studies. Some (Hamblen 1984) quote a rate of between 0.5 and 3%, while others (McCollum & Gray 1990) quote 3 to 5%. A more recent text (Miller 1992) states that dislocation occurs in I to 4% of primary total hip replacements. The Belfast Custom X-press hip system comprises a modular, customized, cemented, titanium stem, together with cobalt chrome or ceramic heads, and is used in conjunction with a cemented Charnley-type socket. Since 1992, over 1500 prostheses have been implanted and documented (Wallace et al 1992, Engela et al 1993, O'Brien et al 1994, Nixon et al 1994, Beverland 1994, James et al 1995). A total of 1023 Custom X-press total hip replacements were reviewed radiographically. The dislocations in this group were compared to a subset (chosen at random from the custom hip database) of 347 arthroplasties who did not dislocate. Several factors were found to influence dislocation: femoral head size was the most important factor in our series. The smaller femoral head size (22.225 mm) was significantly more likely to dislocate, P

大腿義足や坐骨支持付き長下肢装具が小児股関節発育に及ぼす影響

We studied radiologically the growth of hip joints in 4 children who have been using an ishial weight-bearing brace or external prosthesis. They underwent surgery for osteosarcoma in the distal femurs and proximal tibiae before the age of 10 years. Two children received amputation at the proximal thigh and the remaining 2 children underwent a limb salvage procedure. After closure of growth plates in all children, the radiological findings around the affected hip joints such as narrow joint spaces, smaller femoral heads, decrease of bone trabeculae and long proximal femurs were observed in comparison with those of the contralateral side. Among those findings, the decrease of bone trabeculae and long proximal femurs were more indicative that the use of an ishial weight-bearing brace or external prosthesis had influenced the growth of the hip joint.