The Otto Aufranc Award. Image guided navigation system to measure intraoperatively acetabular implant alignment

There has been little clinical research to examine the effects of patient positioning and pelvic motion on the alignment of the acetabular implant during total hip replacement surgery. Until now, no tools were capable of accurately measuring these variables during the actual procedure. As part of a broader program in medical robotics and computer assisted surgery, a clinical system has been developed that includes several enabling technologies. The hip navigation system (HipNav) continuously and precisely measures pelvic location and tracks relative implant alignment intraoperatively. HipNav technology is used to gauge current clinical practice and provide intraoperative feedback to surgeons with the goal of improving the precision and accuracy of acetabular alignment during total hip replacement. This system provides surgeons with a new class of image guided measurement tools and assist devices. These tools successfully were introduced into the clinical practice of surgery with results showing the following: (1) There exist unpredictable and large variations in the initial position of patients' pelves on the operating room table and significant pelvic movement during surgery and during intraoperative range of motion testing; (2) current mechanical acetabular alignment guides do not account for these variations, and result in variable and in the majority of cases unacceptable acetabular alignment; and (3) press fitting oversized acetabular components influences the final cup orientation.     

Results of total hip arthroplasty for Crowe Type III developmental hip dysplasia

From 1969 through 1980, 90 hips in 82 patients had cemented total hip arthroplasty for Type III developmental hip dysplasia. Seventy hips were reviewed at an average of 16.6 years (range, 5-23 years) after operation. Aseptic loosening developed in 53% of acetabular cups and 40% of femoral stems. Despite attempts to place acetabular components in the anatomic center, 18 cups (25.7%) were placed outside that area. Using a measurement method to determine the true acetabular region and approximate femoral head center, final acetabular loosening strongly correlated with initial cup placement. Loosening occurred in 15 of 18 cups (83.3%) initially positioned outside of the true acetabular region compared with loosening in 22 of 52 cups (42.3%) initially positioned within the true acetabular region. Acetabular loosening also correlated with initial lateral displacement or initial superior displacement of the hip center from the approximate femoral head center. Initial cup placement medial to the approximate femoral head center was predictive of successful long term acetabular component fixation. The method of acetabular reconstruction did not affect eventual cup loosening. Placement of the hip arthroplasty center of rotation in or near the true acetabular region is recommended.     

The value of preoperative planning for total hip arthroplasty

To analyse the value and accuracy of preoperative planning for total hip replacement (THR) we digitised electronically and compared the hand-sketched preoperative plans with the pre- and postoperative radiographs of 100 consecutive primary THRs. The correct type of prosthesis was planned in 98%; the agreement between planned and actually used components was 92% on the femoral side and 90% on the acetabular side. The mean (+/- SD) absolute difference between the planned and actual position of the centre of rotation of the hip was 2.5 +/- 1.1 mm vertically and 4.4 +/- 2.1 mm horizontally. On average, the inclination of the acetabular component differed by 7 +/- 2 degrees and anteversion by 9 +/- 3 degrees from the preoperative plans. The mean postoperative leg-length difference was 0.3 +/- 0.1 cm clinically and 0.2 +/- 0.1 cm radiologically. More than 80% of intraoperative difficulties were anticipated. Preoperative planning is of significant value for the successful performance of THR.     

A study of the factors in hip replacement dislocation. Part 2

Dislocation is a dramatic and distressing common complication following total hip replacement. The first article describing this study, published last week, considered some of the factors thought to predispose to dislocation. The authors emphasised the multifactorial nature of hip replacement dislocation and in this second article they examine the factors relating to acetabular position and orientation, and femoral component placement.     

Isolated revision acetabuloplasty using a porous-coated cementless acetabular component without removal of a well-fixed femoral component. A 3- to 9-year follow-up study

The results of isolated acetabular revision performed in 31 patients (32 hips) were monitored for between 3 and 9 years. All femoral components were well fixed and not removed or revised at the time of index surgery. There were 4 hips with little or no acetabular bony defect, 2 hips with pure segmental defects (type I), 10 hips with cavitary defects (type II), 15 with combined segmental cavitary defects (type III), and I with pelvic discontinuity (type IV). All revision acetabular implants were cementless, using a porous-coated hemispheric cup with or without bone-graft. There were four grade I reconstructions, 16 grade II reconstructions, and 12 grade III reconstructions. At final follow-up evaluation 94% of the cups were judged to be stable. Two hips required a second revision acetabuloplasty because of loss of fixation of the cup. The 2 repeat revisions were also done without removal of the femoral component. One acetabular component had evidence of rotational migration, which stabilized and remained nonprogressive. There were no cases of femoral component radiographic or clinical failure. The mean pre and postoperative hip scores were 44 and 83, respectively. The pre- and postoperative pain scores were 12 and 42, respectively. The findings of this study suggest that isolated acetabular revision, using a cementless porous-coated hemispheric cup, can be successfully performed without removing or revising a well-fixed femoral stem and not compromise the final outcome.     

Hemispheric titanium porous coated acetabular component without screw fixation

One hundred fifteen hips in 108 patients with primary total hip arthroplasty using the anatomic porous replacement hemispheric acetabular component implanted without adjunctive screw fixation had a mean postoperative followup time of 6 years (range, 5-7.4 years). Clinical evaluation was performed using the Harris hip score and patient self assessment using a modified Short Form-36 questionnaire. Radiographs were measured for radiolucent lines, polyethylene wear, osteolysis, migration, and fractures. No acetabular metal shell had been revised for loosening or was radiographically loose with or without migration (more than 3 mm) at final followup. Reoperation was done in nine (8%) hips because of polyethylene insert wear or disassembly. No fracture of the acetabular bone occurred at the time of surgery or was observed on radiograph. Fixation of the metal shell was stable, with progressive radiolucent lines observed at final followup in 2% of the hips. Osteolysis was recorded in one patient with two acetabular components. The fixation of noncemented hemispheric porous coated acetabular components is more related to the technique of acetabular bone preparation and press fit implantation than to whether additional screws or peg fixation are used. Fixation of this acetabular component without screws at an average of 6 years after surgery is reproducible and predictable in primary hip arthroplasty. The design of modular polyethylene inserts has been improved and should reduce the wear rate of reoperations of the polyethylene insert.     

Computer assisted orthopaedic surgery with image based individual templates

Recent developments in computer assisted surgery offer promising solutions for the translation of the high accuracy of the preoperative imaging and planning into precise intraoperative surgery. Broad clinical application is hindered by high costs, additional time during intervention, problems of intraoperative man and machine interaction, and the spatially constrained arrangement of additional equipment within the operating theater. An alternative technique for computerized tomographic image based preoperative three-dimensional planning and precise surgery on bone structures using individual templates has been developed. For the preoperative customization of these mechanical tool guides, a desktop computer controlled milling device is used as a three-dimensional printer to mold the shape of small reference areas of the bone surface automatically into the body of the template. Thus, the planned position and orientation of the tool guide in spatial relation to bone is stored in a structural way and can be reproduced intraoperatively by adjusting the position of the customized contact faces of the template until the location of exact fit to the bone is found. No additional computerized equipment or time is needed during surgery. The feasibility of this approach has been shown in spine, hip, and knee surgery, and it has been applied clinically for pelvic repositioning osteotomies in acetabular dysplasia therapy.     

Colchicine in chronic hepatitis B: a pilot study

INTRODUCTION: The authors report the case of an internal rotation of the lower limb, lately ascribed to a posterior placement of the acetabular component during total hip arthroplasty. MATERIAL AND METHOD: A 58 years old female had an irreducible internal rotation of the right hip 3 years after total hip arthroplasty for arthritis. When the hip was extended, the lower limb showed an irreducible internal rotation of 45 degrees. In flexion of the hip this rotation disappeared. AP radiograms showed femur and femoral stem in internal rotation, a healed fracture of the acetabulum, and the acetabular component seemed to be in correct position. On CT scan the acetabular component was 4 cm posterior to the anatomic location, although there was no abnormal anteversion of the stem and acetabular component. Revision, with relocation of the acetabular component, corrected lower limb rotation. DISCUSSION: Posterior position of the acetabular component has not been described as a cause of lower limb malrotation. Normally the strength of the external hip rotators muscles is three times as important as of the internal rotators. The transverse acetabular fracture led to backwards placement of the acetabular component and yelded in an automatic internal rotation of the femur, because the trochanter kept an anatomical position in the horizontal plane. The posteriorised rotation center of the hip had changed the balance of the different rotator muscles, some of them, originally external rotators, becoming internal rotators.     

Progression of radiolucent lines adjacent to the acetabular component and factors influencing migration after Charnley low-friction total hip arthroplasty

We analyzed the progression of radiolucent lines around the acetabular cup after 452 Charnley low-friction arthroplasties that had been performed in 392 patients between 1971 and 1976. The average duration of follow-up was twenty years (range, eleven to twenty-five years) for the 442 hips (382 patients) that had the original component in place at ten years. The demarcation of the bone-cement interface was classified according to the system of Hodgkinson et al. We sought to determine if there was a relationship between the progression of the radiolucent line and the age, gender, and weight of the patient; the level of activity; the preoperative diagnosis; or the amount of wear of the acetabular cup. The demarcation increased over time in 138 (31 per cent) of the 452 hips. Radiographs made at the time of the latest follow-up showed migration of eleven (5 per cent) of the 233 acetabular cups with no demarcation on the initial postoperative radiograph, eighteen (11 per cent) of the 167 cups with type-1 demarcation, twelve (35 per cent) of the thirty-four cups with type-2 demarcation, and thirteen of the eighteen cups with type-3 demarcation. Preoperative acetabular protrusion, inflammatory arthritis, and severe acetabular dysplasia as well as a previous operation were associated with the extent of the radiolucent line on the most recent radiograph (p < or = 0.05 for all). A high level of activity and more than two millimeters of wear of the acetabular cup also were related to the progression of the radiolucent line (p = 0.0004 and p < 0.0001, respectively). Kaplan-Meier survivorship analysis demonstrated that the greater the demarcation on the initial postoperative radiograph, the greater the risk of migration (p < 0.0001, Mantel-Cox test). Our data suggest that, after a Charnley low-friction arthroplasty, any cemented cup, even one with the least amount of demarcation (types 0 and 1), can migrate. As the type of the initial postoperative demarcation increases, so does the risk of migration of the cup, particularly when there is loss of the acetabular bone stock.     

Hip arthroplasty by matching cups

A total hip surface arthroplasty consisting of matching cups and uncemented prosthetic components is a noteworthy operation. The femoral cup obtains cylindrical support from the femoral head which is reamed in the shape of a cylinder. The acetabular cup is metallic with a polyethylene liner. It is mobile over the bone but its position is constrained by contact with the femoral cup and therefore "self-centering." On the femoral side, the cup must be placed strictly in the axis of the femoral neck. The main consideration in femoral head surface replacement is the vitality of the underlying bone. Necrosis was observed in the earliest clinical trials but there have been no cases of necrosis in the past 3 1/2 years. This is attributed to a more limited surgical approach in which only the anterior part of the gluteus medius is divided and all the posterior elements of the hip are preserved. The acetabulum is sufficiently reamed to receive the cup, which protrudes beyond the external margins of the acetabulum in all positions. Errors have been committed while perfecting the prosthetic material, but the results as determined by a 6 1/2 year follow-up on purely metallic cups are encouraging. Metal-polyethylene cups presently under investigation have almost a 2 year follow-up. The reaction of the acetabulum to an uncemented cup is not yet known. However, the existence of 2 sliding surfaces and the fact that the acetabular cup moves only during the extremes of hip movement, is reason to assume that if the acetabulum is not reamed to expose cancellous bone, the risks of protrusion are minimal or delayed. Total surface arthroplasty by concentric cups has been performed in 335 hips to date. The operation is especially recommended when osteotomy is no longer possible and disabling coxarthrosis is present in relatively young patients.     

Additive effect of beraprost on pulmonary vasodilation by inhaled nitric oxide in children with pulmonary hypertension

Using a prospective audit, we have evaluated the efficacy of an integrated autotransfusion regimen which comprised predepositing and intra- and postoperative blood salvage in major orthopaedic surgery. We examined prospectively the records of 1785 patients (1198 females, 5867 males, mean age 62 (range 16-90) yr, preoperative haemoglobin concentration 13.4 (SD 1.4) g dl-1) undergoing total hip arthroplasty (THA, 1229 patients), THA after removal of internal fixation devices (RFD + THA, 18 patients), total knee arthroplasty (TKA, 263 patients), revision surgery of the hip (HR cup + stem revision, 197 patients; cup revision, 53 patients; stem revision, 16 patients) and total knee revision (TKR, nine patients). We estimated that the number of predonations (MSBOS = maximum surgery blood order schedule) was 2 u. for THA, TKA and TKR, and 3 u. for partial or total hip revision and total hip arthroplasty with fixation removal. We found that it was possible to obtain the MSBOS in 1597 patients (89.5%). Homologous red blood cell (HRBC) transfusions were carried out in 131 patients (7.3%). We found that the need to use HRBC was significantly associated with failure to meet the number of MSBOS, female sex, lower preoperative haemoglobin concentration, use of calcium heparin for antithrombosis prophylaxis, more extensive surgery, higher ASA rating and co-existing diseases such as coronary artery disease.     

Polyethylene wear from femoral bipolar neck-cup impingement as a cause of femoral prosthetic loosening

A 33-year-old woman underwent an uncemented bipolar hip arthroplasty for osteoarthrosis of the left hip in 1985. Because of painful aseptic loosening, the bipolar implant was revised to a total hip prosthesis in 1994. Membranous tissues around the implant histologically presented foreign-body reaction against polyethylene debris. The retrieved implant showed polyethylene wear of the rim of the bipolar cup. Three-dimensional measurement of the surface configuration of the polyethylene of the cup indicated that wear debris had been generated almost exclusively from femoral bipolar neck-cup impingement. Volumetric wear in the articulating dome portion of the polyethylene was negligible. This report clearly illustrates how impingement of a bipolar cup on the femoral neck can be a major source of polyethylene wear debris which induces femoral osteolysis and subsequent stem loosening.     

Cemented fixation with bone grafts

Loosening of the acetabular cup in cemented total hip arthroplasty is always accompanied by a loss of bone stock. Acetabular lesions can be reconstructed in several ways. Preoperative planning must be through, and specifically if graft procedures are considered, infection must be ruled out. The treatment of choice is a standardized cemented acetabular revision procedure with tight impaction of morsellized cancellous grafts. The clinical success of the technique is supported by the results of an animal experiment.     

Use of acetabular models in planning complex acetabular reconstructions

The number of patients requiring revision total hip arthroplasty continues to increase each year. Accurate preoperative planning is a key factor in obtaining a good result. Radiographs provide little information concerning the actual extent of the acetabular defects. Computed tomography-generated models of the acetabulum can provide the surgeon with accurate information concerning the size and location of the defects. Evaluation of radiographs and models in 24 cases showed that radiographs alone failed to detect all 13 anterior wall defects (P < .001), 8 of 18 posterior wall defects (44.4%, P < .001), and 8 of 19 segmental central defects (42%, P < .001), all of which were easily identified with the models. This study showed that preoperative planning based on the foam models accurately predicted the actual implant used in 22 of 24 cases (92%).     

Effect of supplementation with chromium picolinate on antibody titers to 5-hydroxymethyl uracil

This study was designed to determine the effect of acetabular abduction on the polyethylene wear rates of the acetabular component. The hypothesis of this study is that acetabular placement, in particular abduction, effects contact forces and therefore polyethylene wear. A total of 364 total hip arthroplasties that were performed between 1974 and 1976 were included in this study. The cemented all-polyethylene acetabular components were the same for each case and came from a single supplier. The polyethylene wear rates were calculated by measuring the shortest radius from the center of the prosthetic femoral head to a point on the outer surface of the acetabular cup. An immediate postoperative radiograph was compared with a follow-up radiograph at least 9.5 years later. A standardized radiograph was used to prevent differences due to magnification. The abduction or inclination of the acetabular cups was measured in all of the patients. The amount of acetabular cup abduction was measured relative to the ischial tuberosity line. The mean abduction was 44.1 degrees with a standard deviation of 9.2 degrees and a median of 44 degrees. The range of abduction was from 0 degrees to 85 degrees. This analysis failed to show a correlation between the amount of acetabular abduction and polyethylene wear rates (Pearson's correlation coefficient = 0.0679; P = .20). With a sample size of 364, there is over a 95% change (statistical power) of detecting an underlying true correlation between wear and abduction that is greater than or equal to 0.20. We were unable to demonstrate a difference in wear that would correlate with the differing degrees of abduction of the acetabular socket. We felt that the radiographic measurements of wear were quite accurate. This method of determining acetabular abduction has also been documented and supported in previous literature and has allowed us to accurately determine acetabular abduction. The results of our study demonstrate that within the normal ranges described by our study, polyethylene wear did not significantly increase with increased abduction of the acetabular component.     

Isolation and cytotoxic evaluation of marine sponge-derived norterpene peroxides

Anatomic placement of the acetabular component should be the surgeon's goal at the time of revision THA. However, Acetabular loosening with subsequent implant migration, progressive superior acetabular bone destruction or severe pelvic osteolysis, may prevent the surgeon from obtaining adequate host bone-implant contact needed for a successful reconstruction while maintaining a normal hip center. The high hip center offers a technique for reconstruction of an acetabulum with severe bony deficiency and where the majority of the remaining host bone is superior to the anatomic hip centre.     

Gothenburg osseointegrated hip arthroplasty. Experience with a novel type of hip design

The culmination of more than 10 years of laboratory and clinical research has been the clinical trial of a novel hip arthroplasty for osseointegration. The femoral component of this Gothenburg hip is a neck retaining, threaded fixture with rotational symmetry, produced in commercially pure titanium with a specific surface texture. Proximally, a standard orthopaedic taper trunnion mates with a 28-mm diameter zirconia head that articulates against the acetabular component. The latter is also of textured commercially pure titanium, encapsulating a thick ultra high molecular weight polyethylene liner. Dedicated alignment guides and cutting instruments ensure accurate bone preparation and implant placement. Limited clinical trials commenced in 1992 and expanded to multicenter clinical trials in 1997. Every hip has been monitored with radiostereometry to measure migration to an accuracy of 0.1 mm. All calcar implanted femoral components show excellent function at 4 to 5 years followup, with no migration revealed by radiostereometry.     

Primary and revision total hip replacement using the Robodoc system

The ROBODOC system was designed to address potential human errors in performing cementless total hip replacement. The system consists of a preoperative planning computer workstation (called ORTHODOC) and a five-axis robotic arm with a high speed milling device as an end effector. The combined experience of the United States Food and Drug Administration multicenter trial and the German postmarket use of the system are reported. The United States study is controlled and randomized with 136 hip replacements performed at three centers (65 ROBODOC and 62 control). Followup was 1 year on 127 hip replacements and 2 years on 93 hip replacements. No differences were found in the Harris hip scores or the Short Form Health Survey outcomes questionnaire. Length of stay also was not different, but the surgical time and blood loss were greater in the ROBODOC group. This was attributed to a learning curve at each center. Radiographs were evaluated by an independent bone radiologist and showed statistically better fit and positioning of the femoral component in the ROBODOC group. Complications were not different, except for three cases of intraoperative femoral fracture in the control group and none in the ROBODOC group. The German study reports on 858 patients, 42 with bilateral hip replacements and this includes 30 revision cases for a total of 900 hip replacements. The Harris hip score rose from 43.7 to 91.5. In these cases the surgical time declined quickly from 240 minutes for the first case to 90 minutes. No intraoperative femoral fractures occurred in 900 cases. Other complications were comparable with total hip replacements performed using conventional techniques. The ROBODOC system is thought to be safe and effective in producing radiographically superior implant fit and positioning while eliminating femoral fractures.     

Ceramic endoprosthesis in total hip arthroplasty

Aluminia-on-aluminia hip prosthesis with titanium alloy stem was used in 255 cases, for 143 patients with cemented acetabular cup and 112 with an uncemented screw cup. The average age of the patients was 62 years. Of the patients, 35 were treated bilaterally. The indication for surgery was osteoarthritis in 186 cases, fractures and nonunions of the hip joint in 34 cases, and congenital dislocations of the hip joint in 16 cases. Previous surgery of the hip joint was recorded for 43 cases. All procedures were primary arthroplasties. Only personal clinical examinations together with radiographic studies were accepted as clinical data. Three patients failed to show up for routine follow-up evaluation and these were excluded from the series. Revision operation was classified as failure. The indications for revision were aseptic loosening, late infection, and fracture of the acrylic cement resulting in loosening of the acetabular or femoral component. The acetabular component was cemented in 143 patients and the mean follow-up period for these patients was 6.7 years (range, 1-12 years). In this series, a revision operation was undertaken for 16 patients (11%). In 12 cases, broken acrylic cement resulted in acetabular aseptic loosening. In the series of 112 patients with uncemented titanium screw cup, the mean follow-up period was 3.6 years (range, 1-7 years) and a revision operation was undertaken in seven cases (7%). In two, the indication was late infection; in one, technical failure; and in two, progression of Pigmented villonodular synovitis. Acetabular aseptic loosening resulted in revision in only two cases. With cementless acetabular component bone transplantation is indicated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dislocation after total hip arthroplasty using the anterolateral abductor split approach

The three basic surgical approaches used most commonly in total hip arthroplasty are transtrochanteric, posterior, and anterolateral. Complications related to each of these surgical approaches have been reported including dislocation, trochanteric nonunion, heterotopic ossification, neurovascular damage, postoperative limp, and implant malalignment. The anterolateral abductor split approach previously has been reported to allow ease of access into the hip joint, optimum joint visualization, protection of neurovascular structures of the hip, and predictable results for postoperative hip function restoration. Reviewing a large consecutive series of primary total hip arthroplasty cases (1518), the authors report an overall dislocation rate less than 1% (12:1518; 0.79%). Stratified by preoperative diagnosis, patients undergoing total hip arthroplasty after trauma, or presenting with congenital dysplastic hip are at the highest risk for postoperative dislocation. Primary total hip arthroplasty using the anterolateral, abductor split approach can minimize the rate of postoperative dislocation in the prevailing preoperative diagnostic categories.